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Sample records for misfit layer compounds

  1. CHALCOGENIDE MISFIT LAYER COMPOUNDS

    NARCIS (Netherlands)

    ROUXEL, J; MEERSCHAUT, A; WIEGERS, GA

    1995-01-01

    Misfit layer chalcogenides (MX)(1+x)(TX(2))(m) (M=Sn, Pb, Sb, Bi, rare earth; T=Ti, V, Cr, Nb, Ta; X=S, Se; 0.08

  2. CHARGE-TRANSFER BETWEEN LAYERS IN MISFIT LAYER COMPOUNDS

    NARCIS (Netherlands)

    WIEGERS, GA

    1995-01-01

    Electron donation from MX double layers to TX(2) sandwiches, the interlayer bonding and the localization of conduction electrons in misfit layer compounds (MX)(p)(TX(2))(n) (M=Sn, Pb, Sb, Bi, rare earth metals; T=Ti, V, Cr, Nb, Ta; X=S, Se; 1.08

  3. CHARGE-TRANSFER BETWEEN LAYERS IN MISFIT LAYER COMPOUNDS

    NARCIS (Netherlands)

    WIEGERS, GA

    1995-01-01

    Electron donation from MX double layers to TX(2) sandwiches, the interlayer bonding and the localization of conduction electrons in misfit layer compounds (MX)(p)(TX(2))(n) (M=Sn, Pb, Sb, Bi, rare earth metals; T=Ti, V, Cr, Nb, Ta; X=S, Se; 1.08

  4. THE MISFIT LAYER COMPOUND (SNSE)1.16NBSE2

    NARCIS (Netherlands)

    WIEGERS, GA; ZHOU, WY

    1991-01-01

    (SnSe)1.16NbSe2 was prepared from the elements at 750-degrees-C. The compound has a misfit layer structure with unit cell dimensions for the SnSe subsystem: a1 = 5.928(1), b1 = 5.970(2), c1 = 12.282(2) angstrom, space group Cm2a, Z = 4 and for the NbSe2 subsystem: a2 = 3.441(1), b2 = 5.971 angstrom

  5. Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

    Directory of Open Access Journals (Sweden)

    Devin R. Merrill

    2015-04-01

    Full Text Available A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by the contradictory material requirements necessary for efficient thermal energy harvest. Misfit layer compounds are highlighted as an example of a highly ordered anisotropic nanocomposite system. Their layered structure provides the opportunity to use multiple constituents for improved thermoelectric performance, through both enhanced phonon scattering at interfaces and through electronic interactions between the constituents. Recently, a class of metastable, turbostratically-disordered misfit layer compounds has been synthesized using a kinetically controlled approach with low reaction temperatures. The kinetically stabilized structures can be prepared with a variety of constituent ratios and layering schemes, providing an avenue to systematically understand structure-function relationships not possible in the thermodynamic compounds. We summarize the work that has been done to date on these materials. The observed turbostratic disorder has been shown to result in extremely low cross plane thermal conductivity and in plane thermal conductivities that are also very small, suggesting the structural motif could be attractive as thermoelectric materials if the power factor could be improved. The first 10 compounds in the [(PbSe1+δ]m(TiSe2n family (m, n ≤ 3 are reported as a case study. As n increases, the magnitude of the Seebeck coefficient is significantly increased without a simultaneous decrease in the in-plane electrical conductivity, resulting in an improved thermoelectric power factor.

  6. X-RAY CRYSTAL-STRUCTURE DETERMINATION OF THE TRICLINIC MISFIT LAYER COMPOUND (SNS)1.20TIS2

    NARCIS (Netherlands)

    WIEGERS, GA; MEETSMA, A; DEBOER, JL; VANSMAALEN, S; HAANGE, RJ

    1991-01-01

    (SnS)1.20TiS2 is a misfit layer compound built of alternately double layers of SnS with distorted rocksalt-type structure and sandwiches of TiS2 slightly distorted compared with those of 1T-TiS2. For comparison with other misfit layer compounds the triclinic subsystems are described in centred unit

  7. CRYSTAL-STRUCTURE DETERMINATION OF THE MISFIT LAYER COMPOUND (HOS)1.23NBS2

    NARCIS (Netherlands)

    WIEGERS, GA; MEETSMA, A; HAANGE, RJ; DEBOER, JL

    1992-01-01

    Single-crystal X-ray diffraction has shown that (HoS)1.23NbS2 is a misfit layer compound built of alternate double layers of HoS, approximately a {001} slice of NaCl-type HoS, and sandwiches of NbS2 with niobium in trigonal prisms of sulphur like niobium in 2H-NbS2. The unit cell dimensions of the H

  8. SUPERSPACE-GROUP APPROACH TO THE MODULATED STRUCTURE OF THE INORGANIC MISFIT LAYER COMPOUND (LAS)1.14NBS2

    NARCIS (Netherlands)

    VANSMAALEN, S

    1991-01-01

    The structure of the inorganic misfit layer compound (LaS)1.14NbS2 is reanalysed in the superspace-group formalism, using the recent single-crystal x-ray diffraction data obtained by Meerschaut, Rabu and Rouxel. Structure refinements make it possible to determine the values of the modulation functio

  9. AN X-RAY PHOTOEMISSION SPECTROSCOPY STUDY OF INTERLAYER CHARGE-TRANSFER IN SOME MISFIT LAYER COMPOUNDS

    NARCIS (Netherlands)

    ETTEMA, ARHF; HAAS, C

    1993-01-01

    The misfit layer compounds with a general formula (MX)1+deltaTX2 (with M = Sn, Pb, Bi or rare earth metal; X = S, Se; T = Ti, V, Cr, Nb, Ta and 0.05 layers with a NaCl-type structure alternated by TX2 sandwiches. The unit cell axes in the plane of the layer

  10. CHARACTERIZATION AND ELECTRICAL TRANSPORT-PROPERTIES OF THE MISFIT LAYER COMPOUNDS (BISE)1.10NBSE2 AND (BISE)1.09TASE2

    NARCIS (Netherlands)

    ZHOU, WY; MEETSMA, A; DEBOER, JL; WIEGERS, GA

    1992-01-01

    Compounds (BiSe)1.10NbSe2 and (BiSe)1.09TaSe2 were prepared by high-temperature reaction of the elements. Crystals were grown by vapor transport. The misfit layer compounds are built of alternate sandwiches NbSe2 (TaSe2) with Nb (Ta) in trigonal prisms of Se and interface modulated double layers of

  11. Photoelectron spectra of the late rare-earth misfit layer compounds (LnS)(1+x)TS2 (Ln=Tb, Dy, Ho; T=Nb, Ta)

    NARCIS (Netherlands)

    Fang, CM; Wiegers, GA; Haas, C

    1997-01-01

    Photoemission spectra (XPS and UPS) are presented for the valence band of misfit layer compounds (LnS)(1+x)TS2 with Ln = Dy, Ho or Tb; T = Nb or Ta. The Nb 4d(x)2 (or Ta 5d(x)2) conduction band is almost filled, which indicates a charge transfer of slightly less than one electron per T from the LnS

  12. Motif of misfit layer compounds (SnS) xTS 2 (T=Ti, V, Nb, Ta) in the matrix of SnS 2

    Science.gov (United States)

    Abramov, S. P.

    1999-09-01

    The possibility of T (T=Ti, V, Nb, Ta) insertion in the layer matrix of SnS 2 (when T≪Sn) presents a special case of intercalation for the specific interactions that are inherent in the misfit layer compounds (SnS) xTS 2 ( x≈1). FT Raman spectra of T xSnS 2 (T=Ti, V) with x≪1 testify to the SnS 2 matrix that is invariable with respect to a charge transfer from T to SnS 2 layers as compared with the pristine SnS 2. At the same time the T xSnS 2 structure ( x≪1) taken as a whole has substantial features in the UV-IR spectra as compared with the pristine SnS 2 but is still a semiconductor at least in the case of T=Ti. This points out in the cluster manner of TS 2 insertion in the matrix of SnS 2 with the interactions that are typical of the misfit layer compounds (SnS) xTS 2 in which metallic conductivity occurs in the TS 2 layers.

  13. Insights from STEM and NBED studies into the local structure and growth mechanism of misfit layered compounds prepared using modulated reactants

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, Ines [Humboldt Univ. Berlin (Germany). Inst. of Physics; Atkins, Ryan; Falmbigl, Matthias; Johnson, David C. [Oregon Univ., Eugene, OR (United States). Dept. of Chemistry; Rudin, Sven P. [Los Alamos National Laboratory, Los Alamos, NM (United States); Neumann, Wolfgang [Humboldt Univ. Berlin (Germany). Inst. of Physics; Oregon Univ., Eugene, OR (United States). Dept. of Chemistry

    2015-02-01

    X-ray diffraction and transmission electron microscopy were used to probe the structure of the misfit compound [(SnSe){sub 1.15}]{sub 1}(VSe{sub 2}){sub 1} grown using an elementally modulated precursor. The specular X-ray diffraction pattern contained only 00l reflections, which yielded a c lattice parameter of 1.203(1) nm. Cross-section STEM revealed alternating layers of SnSe and VSe{sub 2}, in agreement with the structure model refined from the X-ray diffraction pattern using Rietveld refinement. Plan-view transmission electron microscopy revealed the in-plane grain structure of the films, yielding grain sizes in agreement with previously reported in plane X-ray diffraction studies and the cross-section STEM images. The plan view images also contained Moire fringes resulting from grains with different relative tilting on both sides of interfaces as well as Moire fringes resulting from different relative rotations between domains. An energy-filtered nano-beam electron diffraction pattern obtained from at least one domain in the [(SnSe){sub 1.15}]{sub 1}(VSe{sub 2}){sub 1} sample investigated in cross section contained a series of resolvable supercell reflections along the c axis that indicated that the supercell c-axis lattice parameter was a multiple of three times that determined using X-ray diffraction. Energy filtered NBED of plan-view samples showed diffraction patterns from select regions with 12-fold symmetry, indicating that the arrangement of the layers is not rotationally random from layer to layer. This suggests that during the self-assembly of the amorphous modulated elemental precursor, the SnSe and VSe{sub 2} constituent layers must nucleate off the adjacent interfaces of the growing crystal, yielding layers that are locally rotationally aligned with growing crystal. Different processing conditions during the precursor to crystal self-assembly might enable the domain size and/or the extent of order to be controlled.

  14. AB-INITIO SOLUTION OF MISFIT LAYER STRUCTURES BY AUTOMATIC PATTERSON AND DIRECT-METHODS

    NARCIS (Netherlands)

    BEURSKENS, PT; BEURSKENS, G; LAM, EJW; VANSMAALEN, S; FAN, HF

    1994-01-01

    A procedure is presented for the automatic solution of composite (misfit) layer compounds, for the case when the composite crystal structure consists of two types of layer, each of which can be approximately described as a three-dimensional periodic structure with, however, mutually incommensurate l

  15. Shear elastic constants of thin films of the misfit layered compound [(SnSe)1.05]n[MoSe2]n

    Science.gov (United States)

    Li, Dongyao; Mitchson, Gavin; Johnson, David; Schleife, Andre; Cahill, David

    Crystalline materials with interlayer van der Waals bonding typically have low stiffness for shear deformation that reduces the through-plane thermal conductivity and facilitates the use of layered materials as solid-state lubricants. In graphite and MoS2, c44 = 5GPa and 18GPa respectively. The shear modulus of incommensurate layered materials is expected to be strongly reduced relative to ordered crystals but the magnitude of the suppression is currently unknown. We have recently developed an approach for measuring the shear modulus of thin layers using GHz surface acoustic waves (SAW). [(SnSe)1.05]n[MoSe2]n with n =1-4 were prepared as thin films (60 nm) on Si substrates using the modulated elemental reactants technique. The SAW velocity vSAWof Al/[(SnSe)(MoSe2) ]/Si structures was measured using a polydimethylsiloxane (PDMS) phase-shift optical mask in a pump-probe system. c44 was determined by fitting the measured vSAW to the calculated SAW velocity using multi-layer SAW model. c33was measured by picosecond acoustics. c11, c12 and c13 were calculated using density functional theory (DFT) with van der Waals correction. The measured c33 and c44 are compared with the DFT prediction. Experimentally we obtain c44 = 1.9GPa, 1.2GPa, and smaller than 0.05GPa for n =1, 2 and 4. The author acknowledge the support of International Institute for Carbon Neutral Energy Research.

  16. Misfit dislocation generation in SiGe epitaxial layers supersaturated with intrinsic point defects

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, V.I. [Institute for Chemical Problems of Microelectronics, B. Tolmachevsky per. 5, 119017 Moscow (Russian Federation)], E-mail: vivdov@gmail.com; Zakharov, N.D. [Max-Planck-Institut fuer Mikrostrukturphysik, 06120 Halle (Saale) (Germany)], E-mail: zakharov@mpi-halle.mpg.de

    2008-11-03

    Misfit dislocation generation in SiGe/Si(001) heterostructures supersaturated with the vacancies (LT epitaxial growth) or self-interstitials (ion implantation) was studied by transmission electron microscopy. A model of 'optimal' intrinsic point defects (IPDs) for effective strain relaxation is suggested and verified. Supersaturation of compressed SiGe layers with the vacancies ('optimal' IPDs) promotes high strain relaxation, whereas supersaturation with the self-interstitials ('inverse' IPDs) promotes a generation of V-shaped TDs which cannot extend to form MDs.

  17. Misfit Strain in Superlattices Controlling the Electron-Lattice Interaction via Microstrain in Active Layers

    Directory of Open Access Journals (Sweden)

    Nicola Poccia

    2010-01-01

    Full Text Available High-temperature superconductivity (HTS emerges in quite different electronic materials: cuprates, diborides, and iron-pnictide superconductors. Looking for unity in the diversity we find in all these materials a common lattice architecture: they are practical realizations of heterostructures at atomic limit made of superlattices of metallic active layers intercalated by spacers as predicted in 1993 by one of us. The multilayer architecture is the key feature for the presence of electronic topological transitions where the Fermi surface of one of the subbands changes dimensionality. The superlattice misfit strain between the active and spacer layers is shown to be a key variable to drive the system to the highest critical temperature that occurs at a particular point of the 3D phase diagram (, where is the charge transfer or doping. The plots of as a function of misfit strain at constant charge transfer in cuprates show a first-order quantum critical phase transition where an itinerant striped magnetic phase competes with superconductivity in the proximity of a structural phase transition, that is, associated with an electronic topological transition. The shape resonances in these multigap superconductors is associated with the maximum .

  18. Magnetoresistance and magnetothermopower properties of Bi/Ca/Co/O and Bi(Pb)/Ca/Co/O misfit layer cobaltites

    CERN Document Server

    Maignan, A; Hervieu, M; Michel, C; Pelloquin, D; Khomskii, D

    2003-01-01

    Two new compounds of the Bi/Ca/Co/O and Bi(Pb)/Ca/Co/O systems have been prepared. Their structure is built up from the intergrowth of four rock-salt-type layers and one [CoO sub 2 ] hexagonal layer. Both cobaltites exhibit large thermopower values (S sub 3 sub 0 sub 0 sub K approx 140 mu V K sup - sup 1), low resistivity values (rho sub 3 sub 0 sub 0 sub K = 40-60 m OMEGA cm) and small thermal conductivities (kappa sub 3 sub 0 sub 0 sub K approx 1 W K sup - sup 1 m sup - sup 1). Furthermore, these compounds exhibit a negative magnetoresistance, (MR = rho sub H - rho sub H sub sub 0 /rho sub H sub = sub 0), reaching, at 2.5 K, - 85% in 7 T for the Bi/Ca/Co/O misfit cobaltite. A large negative magnetothermopower is also found for these cobaltites in the same temperature range. A qualitative explanation of the observed behaviour is proposed.

  19. Microstructure and thermoelectric properties of screen-printed thick-films of misfit-layered cobalt oxides with Ag addition

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Samson, Alfred Junio; Pryds, Nini

    2012-01-01

    Thermoelectric properties of thick (~60 μm) films prepared by a screen-printing technique using p-type misfit-layered cobalt oxide Ca3Co4O9+δ with Ag addition have been studied. The screen-printed films were sintered in air at various temperatures ranging from 973 K to 1223 K. After each sintering...

  20. Characterization, electrical transport and magnetic properties of the rare earth misfit layer compounds (TbS)(1.21)NbS2, (TbS)(1.20)TaS2, (DyS)(1.22)NbS2 and (DyS)(1.21)TaS2

    NARCIS (Netherlands)

    Zhou, W.Y.; Meetsma, A.; deBoer, J.L.; Wiegers, G.A

    1996-01-01

    X-ray powder and single-crystal X-ray diffraction of the title compounds showed that they are planar intergrowth compounds, built of alternating sandwiches TS2 (T=Nb, Ta) and double layers LnS (Ln=Tb, Dy), present in three orientational variants related by rotations of 120 degrees around the c axis

  1. Lattice and transport properties of the misfit-layered oxide thermoelectric Ca3Co4O9 from first principles

    Science.gov (United States)

    Rebola, Alejandro; Klie, Robert; Zapol, Peter; Ogut, Serdar

    2013-03-01

    The misfit-layered oxide Ca3Co4O9 (CCO) has recently been the subject of many experimental and some theoretical investigations due to its remarkable thermoelectric properties. CCO is composed of two incommensurate subsystems, a distorted rocksalt-type Ca2CoO3 layer sandwiched between hexagonal CoO2 layers. Taking into account that the composition ratio between these subsystems is very close to the golden mean, which is the limit of the sequence of the ratios of consecutive Fibonacci numbers F (n) , we model CCO from first principles[1] by using rational approximants of composition [Ca2CoO3]2 F (n)[CoO2]2 F (n + 1). In the present study, we use 3/2 and 5/3 rational approximants and PBE+U computations to calculate the ab initio phonon dispersion curves, related thermal properties, as well as ab initio electronic transport properties such as DC conductivity and thermopower within the relaxation time approximation by applying the Boltzmann transport theory. Results are compared with available experimental data and potential routes for increasing the thermopower of CCO are discussed.

  2. High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Van Nong, Ngo; Snyder, Gerald Jeffrey;

    2015-01-01

    In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca2.8Lu0.15Ag0.05Co4O9+δ and half-Heusler Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2 alloy was fabricated and characterized. The thermoelectric properties of single components, segmented leg, and the electrical contact resistance...... of the joint part were measured as a function of temperature. The output power generation characteristics of segmented legs were characterized in air under various temperature gradients, DT, with the hot side temperature up to 1153 K. At ΔT ≈756 K, the maximum conversion efficiency reached a value of ∼5......%, which is about 65% of that expected from the materials without parasitic losses. The long-term stability investigation for two weeks at the hot and cold side temperatures of 1153/397 K shows that the segmented leg has good durability as a result of stable and low electrical resistance contacts. 2015...

  3. Influences of misfit strains on liquid phase heteroepitaxial growth

    Science.gov (United States)

    Lu, Yanli; Peng, Yingying; Yu, Genggeng; Chen, Zheng

    2017-10-01

    Influences of misfit strains with different signs on liquid phase heteroepitaxial growth are studied by binary phase field crystal model. It is amazing to find that double islands are formed because of lateral and vertical separation. The morphological evolution of epitaxial layer depends on signs of misfit strains. The maximum atomic layer thickness of double islands under negative misfit strain is larger than that of under positive misfit strain at the same evolutional time, and size differences between light and dark islands is much smaller under negative misfit strain than that of under positive misfit strain. In addition, concentration field and density field approximately have similar variational law along x direction under the same misfit strain but show opposite variational trend under misfit strains with different signs. Generally, free energy of epitaxial growth systems keeps similar variational trend under misfit strains with different signs.

  4. The new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} and the role of dimensionality in the Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub n} series

    Energy Technology Data Exchange (ETDEWEB)

    Trump, Benjamin A., E-mail: btrump1@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218 (United States); Livi, Kenneth J.T. [HRAEM Facility, Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218 (United States); McQueen, Tyrel M., E-mail: mcqueen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2014-01-15

    The synthesis and physical properties of the new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} are reported. Transmission electron microscopy and powder X-ray diffraction show that the structure consists of alternating rock-salt type BiSe layers and hexagonal (TiSe{sub 2}){sub 2} double layers. Resistivity, specific heat, and magnetization measurements show that it has metallic and diamagnetic behaviors. These results are interpreted and discussed in the context of the transition between single-layer (BiSe){sub 1.13}(TiSe{sub 2}), which shows no charge density wave, and infinite-layered (bulk) 1T-TiSe{sub 2}, which undergoes a charge density wave transition at T=202 K. Intercalation with copper, Cu{sub x}(BiSe){sub 1.15}(TiSe{sub 2}){sub 2}, (0≤x≤0.10) is also reported, but unlike Cu{sub x}TiSe{sub 2}, no superconductivity is observed down to T=0.05 K. Thus, the series Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub n} provides an effective approach to elucidate the impact of dimensionality on charge density wave formation and superconductivity. - Graphical abstract: The newly discovered misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} shown in the series (BiSe){sub 1+δ}(TiSe{sub 2}){sub n}. Display Omitted - Highlights: • Reports the structure and properties of the new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2}. • The structure consists of a rock salt type BiSe layer and a double (TiSe{sub 2}){sub 2} layer. • The n=1, 2 misfits (BiSe){sub 1+δ}(TiSe{sub 2}){sub n} are found not to exhibit CDW transitions. • Evidence is presented that there is likely a low-lying CDW excited state. • The series Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub 2} does not superconduct, unlike Cu{sub x}TiSe{sub 2}.

  5. Misfit stress relaxation mechanism in CdTe(100) and CdTe/ZnTe(100) on a GaAs(100) highly mismatched heteroepitaxial layer

    Science.gov (United States)

    Nishino, H.; Sugiyama, I.; Nishijima, Y.

    1996-09-01

    We studied the misfit stress in CdTe(100)/GaAs(100). In general, this highly mismatched system initially forms a ``coincidence interface,'' where seven CdTe lattices match with eight GaAs lattices. In this system, the epilayer is elastically strained by the mismatch remaining between both groups of lattices. Afterward, the misfit stress is gradually relaxed with the generation of misfit dislocations. In this work, we derived a new model to describe this misfit relaxation mechanism and verified it with experimental observations. As introducing the effects of the interface modification, we found that the simple force balance between the substrate and epilayer governed the misfit stress. We assume that the relaxation process during growth is similar to that in CdTe/CdZnTe, since the residual misfit was fairly small. By extending the stress relaxation model of CdTe/GaAs, it is possible to explain the strain in CdTe/ZnTe/GaAs, which contains two highly mismatched interfaces. The threading dislocations in HgCdTe, derived from the CdTe buffer, decreased with increasing CdTe thickness. Assuming that the misfit dislocations are generated by bending threading dislocations, we could explain the dislocation reduction by utilizing the above misfit stress relaxation model. In spite of the extremely large mismatch, the structural quality of CdTe(100)/GaAs(100) was improved due to the relatively small strain remaining in the coincidence interface.

  6. X-ray absorption spectroscopy study of parent misfit-layered cobalt oxide [Sr2O2]qCoO2

    Science.gov (United States)

    Chou, Ta-Lei; Chan, Ting-Shan; Chen, Jin-Ming; Yamauchi, Hisao; Karppinen, Maarit

    2013-06-01

    Here we present a comprehensive X-ray absorption spectroscopy study carried out at Co-L2,3, Co-K, O-K and Sr-K edges for the parent misfit-layered cobalt oxide phase [Sr2O2]0.52CoO2; comparison is made to another misfit-layered oxide [CoCa2O3]0.62CoO2 and the perovskite oxide LaCoO3. A high-quality sample of [Sr2O2]0.52CoO2 was obtained through ultra-high-pressure synthesis using Sr3Co2O6 and Sr(OH)2•8H2O as starting materials. Different dosages of KClO3 were mixed with the raw materials as an oxygen source and tested, but it was found that the window for the redox control of [Sr2O2]0.52CoO2 is rather narrow. From Co-K and Co-L2,3 spectra a mixed III/IV valence state is revealed for cobalt in [Sr2O2]0.52CoO2, but the average valence value is a little lower than in [CoCa2O3]0.62CoO2. Then, Sr-K spectrum indicates that the [Sr2O2] double-layer block in [Sr2O2]0.52CoO2 clearly deviates from the cubic SrO rock-salt structure, suggesting a more complicated coordination environment for strontium. This together with a somewhat low Co-valence value and the fact that the phase formation of [Sr2O2]0.52CoO2 required the presence of Sr(OH)2•8H2O in the high-pressure synthesis suggest that the [Sr2O2] block contains OH groups, i.e. [Sr2(O,OH)2]0.52CoO2.

  7. DAR Assisted Layer-by-Layer Assembly of Aromatic Compounds

    Institute of Scientific and Technical Information of China (English)

    姜思光; 陈晓东; 张莉; 刘鸣华

    2003-01-01

    A facile DAR (diphenylamine-4-diazonium-formaldehyde resin)assisted layer-by-layer (LbL) assembly of uitrathin organic film of aromatic compounds has been investigated. The muitilayer of pyrene or anthracene was fabricated through simple dipping of the glass slide into the mixed solution of DAR with the target compounds. In this method, DAR acted as an assistant compound to help the assembling of the aromatic compounds. Such a convenient deposition method not only reserves the advantages of the traditional LbL technique but also simplifies the technique and extends the effectiveness of LbL technique to small molecules without any charge.

  8. Nano-islands on a composite substrate with misfit dislocations

    Science.gov (United States)

    Ovid'ko, I. A.; Sheinerman, A. G.

    Spatial arrangements of nano-islands (quantum dots) on the free surface of a composite two-layer substrate containing misfit dislocations of edge type are theoretically examined. It is shown that the elastic interaction between misfit dislocations and nano-islands is capable of causing coagulation of nano-islands. The coagulation of nano-islands is shown to be favourable when the upper-layer thickness is smaller than a critical thickness, H0. An analytical form of H0 is presented for the partial case with four-to-one correspondence between nano-islands and cells of the misfit dislocation network.

  9. Magnetic phase transitions in layered intermetallic compounds

    Science.gov (United States)

    Mushnikov, N. V.; Gerasimov, E. G.; Rosenfeld, E. V.; Terent'ev, P. B.; Gaviko, V. S.

    2012-10-01

    Magnetic, magnetoelastic, and magnetotransport properties have been studied for the RMn2Si2 and RMn6Sn6 (R is a rare earth metal) intermetallic compounds with natural layered structure. The compounds exhibit wide variety of magnetic structures and magnetic phase transitions. Substitution of different R atoms allows us to modify the interatomic distances and interlayer exchange interactions thus providing the transition from antiferromagnetic to ferromagnetic state. Near the boundary of this transition the magnetic structures are very sensitive to the external field, temperature and pressure. The field-induced transitions are accompanied by considerable change in the sample size and resistivity. It has been shown that various magnetic structures and magnetic phase transitions observed in the layered compounds arise as a result of competition of the Mn-Mn and Mn-R exchange interactions.

  10. Intercalation compounds involving inorganic layered structures

    Directory of Open Access Journals (Sweden)

    CONSTANTINO VERA R. L.

    2000-01-01

    Full Text Available Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.

  11. TEM study of the (SbS){sub 1+δ}(NbS{sub 2}){sub n}, (n=1, 2, 3; δ~1.14, 1.20) misfit layer phases

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Herrero, A., E-mail: adriangh@pdi.ucm.es [ICTS Centro Nacional de Microscopía Electrónica, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Landa-Cánovas, A.R. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain); Otero-Díaz, L.C. [Dpto. Química Inorgánica, Fac. CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2015-10-15

    In the Sb–Nb–S system four new misfit layer phases have been found and carefully investigated via Transmission Electron Microscopy (TEM). Their structures are of composite modulated structure type with stoichiometries that can be formulated as (SbS){sub 1+δ}(NbS{sub 2}){sub n}; for n=1, δ~1.14 and 1.19; for n=2, δ~1.18 and for n=3, δ~1.19. Selected Area Electron Diffraction (SAED) patterns show an almost commensurate fit between the pseudo-tetragonal (SbS) and the pseudo-orthohexagonal (NbS{sub 2}){sub n} subcells along the misfit direction a, with 3(SbS)≈5(NbS{sub 2}), being b the same for both sub-lattices and c the stacking direction. For n=1, a commensurate phase with 4a{sub SbS}=7a{sub NbS2} has also been observed. In addition to the characteristic misfit and associated modulation of the two sub-structures, a second modulation is also present which appears to be primarily associated with the (SbS) sub-structure of both the n=1 and n=2 phases. High Resolution Transmission Electron Microscopy (HRTEM) images show ordered stacking sequences between the (SbS) and (NbS{sub 2}){sub n} lamellae for each of the four phases, however, disordered intergrowths were also occasionally found. Most of the crystals showed different kinds of twinning defects on quite a fine scale. Many crystals showed curled up edges. In some cases the lamellar crystals were entirely folded giving rise to similar diffraction patterns as found for cylindrical crystals. - Graphical abstract: Idealized structure models of the first three members of the homologous series (SbS){sub 1+δ}(NbS{sub 2}){sub n}. - Highlights: • Transmission Electron Microscopy study of misfit layer sulfides (SbS){sub 1+δ}(NbS{sub 2}){sub n}. • The structures consist of a (SbS) layer interleaved between n (NbS{sub 2}) layers. • Two different members n=1, one n=2 and one n=3 have been studied. • Twinning, intergrowths and different modulations in the (SbS) substructure.

  12. Study on austenitic nitrocarburizing without compound layer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X. [Univ. of Petroleum, Dongying, Shandong (China); Kong, C.; Qiao, Y. [Shandong Polytechnic Univ., Jinan, Shandong (China)

    1995-12-31

    This paper presents an advanced austenitic nitrocarburizing process. Medium-carbon steel was used in austenitic nitrocarburizing with methanol/ammonia atmospheres. A particular hardened case without compound layer was obtained at 680 C processing temperature and a moderate nitrogen potential level and for steel 45 nitrocarburized, there is a fine-grain region beneath the austenite case. The forming and developing mechanism of the fine-grain region was analyzed and the microhardness profiles of the layer before and after ageing were determined. Having the advantages of shorter processing time and a superior hardened case, this treatment is expected to supersede the conventional ferritic nitrocarburizing process in many wear resistance applications.

  13. Oxyfluoride Chemistry of Layered Perovskite Compounds

    Directory of Open Access Journals (Sweden)

    Yoshihiro Tsujimoto

    2012-03-01

    Full Text Available In this paper, we review recent progress and new challenges in the area of oxyfluoride perovskite, especially layered systems including Ruddlesden-Popper (RP, Dion-Jacobson (DJ and Aurivillius (AV type perovskite families. It is difficult to synthesize oxyfluoride perovskite using a conventional solid-state reaction because of the high chemical stability of the simple fluoride starting materials. Nevertheless, persistent efforts made by solid-state chemists have led to a major breakthrough in stabilizing such a mixed anion system. In particular, it is known that layered perovskite compounds exhibit a rich variety of O/F site occupation according to the synthesis used. We also present the synthetic strategies to further extend RP type perovskite compounds, with particular reference to newly synthesized oxyfluorides, Sr2CoO3F and Sr3Fe2O5+xF2−x (x ~ 0.44.

  14. Nucleation, propagation, electronic levels and elimination of misfit dislocations in III-V semiconductor interfaces. Final report, September 1, 1986--August 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Ast, D.G.; Watson, G.P.; Matragrano, M.

    1995-03-01

    Misfit dislocations in gallium arsenides, indium arsenides, and zinc selenides are discussed. The growth of strained epitaxial layers, isolation and nucleation, thermal stability, and electronic and structural characteristics of misfit dislocations are described.

  15. Development of compound layer during nitriding and nitrocarburising

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.

    2010-01-01

    The development of the compound layer during gaseous nitriding and nitrocarburising of Fe-based material is described. The first nucleation of the compound layer at the surface depends on the competition between dissociation of ammonia and the removal nitrogen from the surface by solid state...... diffusion and desorption or the competition with a carburising reaction. During layer growth surface reactions as well as solid state diffusion and phase transformations determine the layer growth kinetics....

  16. Effect of Misfit Dislocation Originated from Strained Layer on Photoluminescence Properties of InxGa1-xN/GaN Multiple Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    L(U) Wei; LI Da-Bing; LI Chao-Rong; CHEN Gang; ZHANG Ze

    2005-01-01

    @@ Inx Ga1-xN/GaN multiple quantum well (MQW) samples with strain-layer thickness larger/less than the critical one are investigated by temperature-dependent photoluminescence and transmission electron microscopy, and double crystal x-ray diffraction.For the sample with the strained-layer thickness greater than the critical thickness, we observe a high density of threading dislocations generated at the MQW layers and extended to the cap layer.These dislocations result from relaxation of the strain layer when its thickness is beyond the critical thickness.For the sample with the strained-layer thickness greater than the critical thickness, temperature-dependent photoluminescence measurements give evidence that dislocations generated from the MQW layers due to strain relaxation are main reason of the poor photoluminescence property, and the dominating status change of the main peak with increasing temperature is attributed to the change of the radiative recombination from the areas including dislocations to the ones excluding dislocations.

  17. Nucleation, propagation, electronic levels and elimination of misfit dislocations in III-V semiconductor interfaces. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Watson, G.P.; Matragrano, M.

    1995-03-01

    This report discusses the following topics: strained layer defects; the structural and electronic characteristics of misfit dislocations; requirements for the growth of high quality, low defect density InGaAs strained epitaxial layers; the isolation and nucleation of misfit dislocations in strained epitaxial layers grown on patterned, ion-damaged GaAs; the effect of pattern substrate trench depth on misfit dislocation density; the thermal stability of lattice mismatched InGaAs grown on patterned GaAs; misfit dislocations in ZnSe strained epitaxial layers grown on patterned GaAs; and the measurement of deep level states caused by misfit dislocations in InGaAs/GaAs grown on patterned GaAs substrates.

  18. Microstructural and compositional Evolution of Compound Layers during Gaseous Nitrocarburizing

    DEFF Research Database (Denmark)

    Du, Hong; Somers, Marcel A.J.; Ågren, John

    2000-01-01

    Compound layers developed at 848 K during gaseous nitrocarburizing of iron and iron-carbon specimens were investigated for several combinations of N and C activities imposed at the specimen surface by gas mixtures of NH3, N2, CO2 and CO. The microstructural evolution of the compound layer...... evolution and the growth kinetics of the compound layers formed is discussed for the iron substrate. The results indicate that the microstructure is governed by a fast C and a slow N absorption at the surface in an early stage of gaseous nitrocarburizing. The influence of carbon in the substrate...... on the microstructural and compositional evolution and on the growth kinetics was evaluated from comparing the results obtained for a normalised Fe-0.8C alloy with those for iron under identical nitrocar-burizing conditions....

  19. The effect of Cr substitution on the structure and properties of misfit-layered Ca{sub 3}Co{sub 4−x}Cr{sub x}O{sub 9+δ} thermoelectric oxides

    Energy Technology Data Exchange (ETDEWEB)

    Prasoetsopha, Natkrita [Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Pinitsoontorn, Supree, E-mail: psupree@kku.ac.th [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen University, Khon Kaen 40002 (Thailand); Kamwanna, Teerasak; Amornkitbamrung, Vittaya [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen University, Khon Kaen 40002 (Thailand); Kurosaki, Ken; Ohishi, Yuji; Muta, Hiroaki; Yamanaka, Shinsuke [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2014-03-05

    Highlights: • The effect of Cr doping in Ca{sub 3}Co{sub 4−x}Cr{sub x}O{sub 9+δ} on thermoelectric properties was studied. • XANES and XPS spectra confirm charge states of +3.5 and >+4.5 for Cr ion. • Thermoelectric variation was due to charge states and ionic radii of Co and Cr ions. • The highest ZT of 0.19 at 1073 K was obtained for the Ca{sub 3}Co{sub 3.85}Cr{sub 0.15}O{sub 9+δ} sample. -- Abstract: Misfit-layered Ca{sub 3}Co{sub 4−x}Cr{sub x}O{sub 9+δ} (0 ⩽ x ⩽ 0.2) powders were synthesized by a simple thermal hydro-decomposition method and then fabricated to form highly dense ceramics using spark plasma sintering. X-ray diffraction, and a field emission scanning electron microscope equipped with an energy dispersive X-ray spectrometer were used to verify the single phase of Ca{sub 3}Co{sub 4}O{sub 9+δ} for the samples with x = 0, 0.05, 0.10 and 0.15. The characteristic plate-like grain structure was observed. The chemical composition of the fabricated samples was found to be close to nominal composition. The thermoelectric measurement showed that Cr doping has an influence on the thermoelectric properties. The resistivity and the Seebeck coefficient increased while the thermal conductivity was suppressed when Cr was added into the system. Explanation of the change in thermoelectric properties was discussed regarding the difference in the charge states and the ionic radii between Co and Cr ions. The highest ZT of 0.19 at 1073 K was obtained for the Ca{sub 3}Co{sub 3.85}Cr{sub 0.15}O{sub 9+δ} sample. In addition, the paramagnetic property was observed in all samples at room temperature.

  20. Surface modification of inorganic layer compound with organic compound and preparation of thin films

    Science.gov (United States)

    Tagaya, Hideyuki; Morioka, Hiroyuki; Ogata, Sumikazu; Karasu, Masa; Kadokawa, Jun-ichi; Chiba, Koji

    1997-11-01

    Water treated Zn/Al layered double hydroxide (LDH) was prepared by the reaction of LDH oxide and water. By the reaction of the water treated Zn/Al LDH or amorphous metal hydroxide and organic oxychloride, surface modified inorganic layer compounds were prepared. Their layer structures were similar to those of the orginal LDHs except the reaction product of amorphous metal hydroxide and benzoyl chloride. Interlayer spacings of the reaction products were 0.77 to 2.67 nm depending on the size and number of function groups of organic compounds.

  1. Microstructural and compositional evolution of compound layers during gaseous nitrocarburizing

    Science.gov (United States)

    Du, Hong; Somers, Marcel A. J.; Agren, John

    2000-01-01

    Compound layers developed at 848 K during gaseous nitrocarburizing of iron and iron-carbon specimens were investigated for several combinations of N and C activities imposed at the specimen surface by gas mixtures of NH3, N2, CO2, and CO. The microstructural evolution of the compound layer was studied by light microscopy and by X-ray diffraction analysis. Composition-depth profiles were determined by electron probe (X-ray) microanalysis. Layer growth kinetics was investigated by layer thickness measurements. The influence of the N and C activities on the microstructural and compositional evolution and the growth kinetics of the compound layers formed is discussed for the iron substrate. The results indicate that the microstructure is governed by a fast C and a slow N absorption at the surface in an early stage of gaseous nitrocarburizing. The influence of carbon in the substrate on the microstructural and compositional evolutions and on the growth kinetics was evaluated from comparing the results obtained for a normalized Fe-0.8C alloy with those for iron under identical nitrocarburizing conditions.

  2. Microstructural and compositional evolution of compound layers during gaseous nitrocarburizing

    Energy Technology Data Exchange (ETDEWEB)

    Du, H.; Somers, M.A.J.; Aagren, J.

    2000-01-01

    Compound layers developed at 848 K during gaseous nitrocarburizing of iron and iron-carbon specimens were investigated for several combinations of N and C activities imposed at the specimen surface by gas mixtures of NH{sub 3}, N{sub 2}, CO{sub 2}, and CO. The microstructural evolution of the compound layer was studied by light microscopy and by X-ray diffraction analysis. Composition-depth profiles were determined by electron probe (X-ray) microanalysis. Layer growth kinetics was investigated by layer thickness measurements. The influence of the N and C activities on the microstructural and compositional evolution and the growth kinetics of the compound layers formed is discussed for the iron substrate. The results indicate that the microstructure is governed by a fast C and a slow N absorption at the surface in an early stage of gaseous nitrocarburizing. The influence of carbon in the substrate on the microstructural and compositional evolutions and on the growth kinetics was evaluated from comparing the results obtained for a normalized Fe-0.8C alloy with those for iron under identical nitrocarburizing conditions.

  3. A misfit function tolerating inconsistent data

    KAUST Repository

    Huang, Yunsong

    2014-08-05

    Inversion methods that do not model all of the physical events in the observed data lead to inconsistent sets of equations. This often results in serious artifacts in the inverted model. To mitigate this problem, I propose a misfit function that partly ignores the unexplainable arrivals in the data due to modeling limitation. This is tested on least squares migration of synthetic P–P arrivals, albeit P–S reflections exist in the observed data in addition, to demonstrate that in this case the new misfit is more robust than the standard L2 misfit.

  4. High quality thin films of thermoelectric misfit cobalt oxides prepared by a chemical solution method

    Science.gov (United States)

    Rivas-Murias, Beatriz; Manuel Vila-Fungueiriño, José; Rivadulla, Francisco

    2015-01-01

    Misfit cobaltates ([Bi/Ba/Sr/Ca/CoO]nRS[CoO2]q) constitute the most promising family of thermoelectric oxides for high temperature energy harvesting. However, their complex structure and chemical composition makes extremely challenging their deposition by high-vacuum physical techniques. Therefore, many of them have not been prepared as thin films until now. Here we report the synthesis of high-quality epitaxial thin films of the most representative members of this family of compounds by a water-based chemical solution deposition method. The films show an exceptional crystalline quality, with an electrical conductivity and thermopower comparable to single crystals. These properties are linked to the epitaxial matching of the rock-salt layers of the structure to the substrate, producing clean interfaces free of amorphous phases. This is an important step forward for the integration of these materials with complementary n-type thermoelectric oxides in multilayer nanostructures. PMID:26153533

  5. High quality thin films of thermoelectric misfit cobalt oxides prepared by a chemical solution method.

    Science.gov (United States)

    Rivas-Murias, Beatriz; Manuel Vila-Fungueiriño, José; Rivadulla, Francisco

    2015-07-08

    Misfit cobaltates ([Bi/Ba/Sr/Ca/CoO]n(RS)[CoO2]q) constitute the most promising family of thermoelectric oxides for high temperature energy harvesting. However, their complex structure and chemical composition makes extremely challenging their deposition by high-vacuum physical techniques. Therefore, many of them have not been prepared as thin films until now. Here we report the synthesis of high-quality epitaxial thin films of the most representative members of this family of compounds by a water-based chemical solution deposition method. The films show an exceptional crystalline quality, with an electrical conductivity and thermopower comparable to single crystals. These properties are linked to the epitaxial matching of the rock-salt layers of the structure to the substrate, producing clean interfaces free of amorphous phases. This is an important step forward for the integration of these materials with complementary n-type thermoelectric oxides in multilayer nanostructures.

  6. A radiographic analysis of implant component misfit.

    LENUS (Irish Health Repository)

    Sharkey, Seamus

    2011-07-01

    Radiographs are commonly used to assess the fit of implant components, but there is no clear agreement on the amount of misfit that can be detected by this method. This study investigated the effect of gap size and the relative angle at which a radiograph was taken on the detection of component misfit. Different types of implant connections (internal or external) and radiographic modalities (film or digital) were assessed.

  7. Misfit in Inconel-Type Superalloy

    Directory of Open Access Journals (Sweden)

    Pavel Strunz

    2013-01-01

    Full Text Available An important parameter for the characterization of microstructural changes in nickel base superalloys is the misfit - the relative difference between lattice parameters of γ matrix and γ′ precipitates. The misfit in IN738LC superalloy was examined at POLDI time-of-flight (TOF neutron diffractometer both at room temperature and in situ at elevated temperatures using a high-temperature furnace. A careful out-of-furnace measurement yielded the lattice parameters of both γ and γ′ phase at room temperature (aγ=3.58611(10 Å, aγ′=3.58857(17 Å as well as the misfit (equal to 6.9(6×10-4. The in situ measurement at elevated temperatures provided the temperature dependence of the lattice parameters of γ (up to 1120°C and γ′ (up to 1000°C. Using these data, the evolution of the misfit with temperature was calculated. The misfit decreases with increasing temperature until it reaches zero value at a temperature around 800°C. Above 800°C, it becomes negative.

  8. The Role of Misfit Dislocations in Strength Enhancement of Cu/Ni Microlaminates

    Institute of Scientific and Technical Information of China (English)

    CHENG Dong; YAN Li; YAN Zhi-jun

    2004-01-01

    This paper simulated the nanoindentations of Cu/Ni thin films with 2D Molecular Dynamics Simulations (MDS) and examined the effects of the misfit dislocations on the mechanical properties of the microlaminates. The misfit dislocation network plays an important role in strength enhancement of Cu/Ni microlaminates because of its resistance to glide dislocations. But the strengthening also relies on the wavelength, which is defined as the thickness of adjacent two layers in microlaminates. When the wavelength is less than the critical value λc, the stress concentration caused by the movement of misfit dislocations will make Cu/Ni microlaminates weaken. Also, the critical wavelength should be more than the depth at which the dislocation nucleates in the homogeneous layer.

  9. Preparation and characterization of new mixed sandwiched layered compounds Ln/sub 32/Nb/sub 28/S/sub 88/ (Ln = La, Ce)

    Energy Technology Data Exchange (ETDEWEB)

    Meerschaut, A.; Rabu, P.; Rouxel, J.

    1989-01-01

    New ternary Ln/sub 32/Nb/sub 28/S/sub 88/ (Ln = La, Ce) compounds have been obtained. They crystallize in the orthorhombic space group (Ccca) with a = 23.031(9) /angstrom/, b = 23.216(6) /angstrom/, c = 5.806(2) /angstrom/, and a = 22.877(9) /angstrom/, b = 23.127(13) /angstrom/, c = 5.775(2) /angstrom/ for La/sub 32/Nb/sub 28/S/sub 88/ and Ce/sub 32/Nb/sub 28/S/sub 88/, respectively. The structure of La/sub 32/Nb/sub 28/S/sub 88/ (Z = 1) has been refined until R = 0.155 for 639 reflections with I />=/ 4sigmaI and 56 variables. The structure may be described as a mixed sandwiched layered type where /absolute value/NbS/sub 2/ and /absolute value/LaS slabs alternate. These new compounds may be classified as misfit layer compounds.

  10. Titanium nitride as a seed layer for Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Niesen, Alessia, E-mail: aniesen@physik.uni-bielefeld.de; Glas, Manuel; Ludwig, Jana; Schmalhorst, Jan-Michael; Reiss, Günter [Center for Spinelectronic Materials and Devices, Bielefeld University (Germany); Sahoo, Roshnee; Ebke, Daniel [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Arenholz, Elke [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-12-28

    Titanium nitride (TiN) shows low resistivity at room temperature (27 μΩ cm), high thermal stability and thus has the potential to serve as seed layer in magnetic tunnel junctions. High quality TiN thin films with regard to the crystallographic and electrical properties were grown and characterized by x-ray diffraction and 4-terminal transport measurements. Element specific x-ray absorption spectroscopy revealed pure TiN inside the thin films. To investigate the influence of a TiN seed layer on a ferro(i)magnetic bottom electrode in magnetic tunnel junctions, an out-of-plane magnetized Mn{sub 2.45}Ga as well as in- and out-of-plane magnetized Co{sub 2}FeAl thin films were deposited on a TiN buffer, respectively. The magnetic properties were investigated using a superconducting quantum interference device and anomalous Hall effect for Mn{sub 2.45}Ga. Magneto optical Kerr effect measurements were carried out to investigate the magnetic properties of Co{sub 2}FeAl. TiN buffered Mn{sub 2.45}Ga thin films showed higher coercivity and squareness ratio compared to unbuffered samples. The Heusler compound Co{sub 2}FeAl showed already good crystallinity when grown at room temperature on a TiN seed-layer.

  11. Rapid misfit dislocation characterization in heteroepitaxial III-V/Si thin films by electron channeling contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Carnevale, Santino D. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, 43210 (United States); Deitz, Julia I. [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, 43210 (United States); Carlin, John A. [Institute for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States); Picard, Yoosuf N.; De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Ringel, Steven A. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, 43210 (United States); Institute for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States); Grassman, Tyler J., E-mail: grassman.5@osu.edu [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, 43210 (United States)

    2014-06-09

    Electron channeling contrast imaging (ECCI) is used to characterize misfit dislocations in heteroepitaxial layers of GaP grown on Si(100) substrates. Electron channeling patterns serve as a guide to tilt and rotate sample orientation so that imaging can occur under specific diffraction conditions. This leads to the selective contrast of misfit dislocations depending on imaging conditions, confirmed by dynamical simulations, similar to using standard invisibility criteria in transmission electron microscopy (TEM). The onset and evolution of misfit dislocations in GaP films with varying thicknesses (30 to 250 nm) are studied. This application simultaneously reveals interesting information about misfit dislocations in GaP/Si layers and demonstrates a specific measurement for which ECCI is preferable versus traditional plan-view TEM.

  12. Faraday effect in III-VI layer compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gavaleshko, N.P.; Lyakhovich, A.N.; Vatamanyuk, P.P.; Savchuk, A.I. (Chernovitskij Gosudarstvennyj Univ. (Ukrainian SSR))

    1982-10-01

    The Faraday effect is investigated in fields up to 20 T and at temperatures from 77 to 300 K applied to the layer semiconductors GaS, GaSe, and InSe. As an example applicable to the InSe crystals, it is shown possible to separate the direct and indirect forbidden transitions both contributing to the Faraday rotation (FR). The oscillatory nature of the FR spectrum at lower temperatures is proved to be due to the exciton contribution. This is the original report about the FR observed in the depth of the fundamental absorption of InSe crystals. The linearity of the FR in the magnetic field is shown to hold for all the compounds under consideration up to 20 T. The observed data are analyzed in order to estimate some band and exciton parameters of the III-VI semiconductors.

  13. Atomic layer epitaxy of 3-5 compounds

    Science.gov (United States)

    Dapkus, P. D.; Wittig, C.; Allen, S.

    1986-08-01

    This program is intended to develop a process for the growth of GaAs and related compounds by Atomic Layer Epitaxy (ALE). The program involves fundamental studies of gas phase kinetics of the organometallic and hydrides to be used in the process as well as surface reaction studies to determine the surface of various organometallics. We have chosen in this program to effect ALE growth in a dense H2 atmosphere. We believe that the reactivity of H2 is important to the removal, by hydrogenation, of the alkyl radicals from the growing surface. To better understand the process we are pursuing fundamental information in two areas. First, basic measurements of the reactivity band reaction products of organometallics and hydrides and of photogenerated species with compound semiconductor surfaces are being undertaken that will determine the feasibility of using photoactivation and in thermal catalytic reactions in the gas phase to accomplish ALE. Second, epitaxial growth experiments are being performed to determine the feasibility of an ALE process employing photodecomposition of surface absorbed species as well as thermal catalytic reactions.

  14. First-principles modeling of magnetic misfit interfaces

    KAUST Repository

    Grytsyuk, Sergiy

    2013-08-16

    We investigate the structural and magnetic properties of interfaces with large lattice mismatch, choosing Pt/Co and Au/Co as prototypes. For our first-principles calculations, we reduce the lattice mismatch to 0.2% by constructing Moiré supercells. Our results show that the roughness and atomic density, and thus the magnetic properties, depend strongly on the substrate and thickness of the Co slab. An increasing thickness leads to the formation of a Co transition layer at the interface, especially for Pt/Co due to strong Pt-Co interaction. A Moiré supercell with a transition layer is found to reproduce the main experimental findings and thus turns out to be the appropriate model for simulating magnetic misfit interfaces.

  15. Stranski-Krastanov mechanism of growth and the effect of misfit sign on quantum dots nucleation

    Science.gov (United States)

    Prieto, J. E.; Markov, I.

    2017-10-01

    The thermodynamics of the Stranski-Krastanov mode of epitaxial growth and the effect of the sign of the lattice misfit are discussed. The Stranski-Krastanov mode of growth represents a sequence of layer-by-layer or Frank-van der Merwe growth followed by the formation of three-dimensional (3D) islands or Volmer-Weber growth. The occurrence of both growth modes mentioned above is in compliance with the wettability criterion of Bauer. The positive wetting function required for the occurrence of the Volmer-Weber growth is originated by the vertical displacements of the atoms close to the edges of the two-dimensional (2D) islands as a result of the relaxation of the lattice misfit. The monolayer high islands become unstable against bilayer islands, bilayer islands in turn become unstable against trilayer islands, etc. beyond some critical islands sizes. Monolayer islands appear as necessary precursors of three-dimensional (3D) islands. The critical island size for mono-bilayer transformation increases steeply with decreasing lattice misfit and diverges at a critical value of the misfit. This value divides the regions of Frank-van der Merwe and Stranski-Krastanov modes in a phase diagram of coordinates wetting-misfit. The transformation of monolayer to multilayer islands takes place either by consecutive nucleation and growth of 2D islands (layer-by-layer transformation), or by nucleation and lateral (2D) growth of multilayer islands (multilayer 2D transformation). The former occurs in the case of ;stiff; overlayer materials and mostly in compressed overlayers. The latter takes place in the case of ;soft; materials like Pb and In, mostly in tensile overlayers. Tensile films show non-nucleation transformation compared with the nucleation-like behavior of compressed films.

  16. Structure and antibacterial activity of new layered perovskite compounds

    Institute of Scientific and Technical Information of China (English)

    TAN Shao-zao; ZHANG Li-ling; XIA Liao-yuan; LIU Ying-liang; LI Du-xin

    2007-01-01

    New layered perovskite compounds, AgxNa2-xLa2Ti3O10 (x=0.2, 0.3 and 0.5) were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution and characterized by energy dispersive X-ray analysis(EDX), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). The ion-exchange processes were optimized, and the antibacterial activity, light permanency and water-resistance were evaluated. Surprisedly, no significant changes in crystal structure of Na2La2Ti3O10 are found by the exchange of silver ions. The Ag0.3Na1.7La2Ti3O10 particles conglomerate obviously with irregular shape and size. Ag0.3Na1.7La2Ti3O10, possessing the minimum inhibitory concentrations(MICs) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) of 180 mg/L and 240 mg/L, has high antibacterial activity, good light permanency and water-resistance. The ionic state silver in AgxNa2-xLa2Ti3O10 is the antibacterial active component.

  17. Separation of nonionic compounds by electrokinetic chromatography using an inorganic layered compound as a pseudostationary phase.

    Science.gov (United States)

    Koike, Ryo; Kitagawa, Fumihiko; Otsuka, Koji

    2008-03-01

    The use of an inorganic layered compound as a pseudostationary phase (PSP) in EKC was investigated. A synthetic smectite, which is the most typical swellable clay mineral, with an average diameter of 130 nm was selected as the PSP. The retention characteristics of the smectite and on-line sample concentration by sweeping were examined for the analysis of polyoxyethylene mono phenyl ethers (PPEs) with different degrees of ethoxylation. The retention factor was increased with increase in the number of ethylene oxide groups and a good separation of the PPE homologs was achieved by smectite-EKC. The RSD of the migration time, plate number, and peak area were 0.60, 8.3, and 2.7% (n = 5), respectively. The developed method can be applied to the analysis of PPEs in commercially available consumer products without any sample pretreatments. In addition, ca. 100-fold sensitivity enhancements for the PPEs with high retention factors were obtained by sweeping.

  18. (3+2)-Dimensional superspace approach to the structure of the incommensurate intergrowth compound - (sbs)(1.15)tis2

    NARCIS (Netherlands)

    Ren, Y; Meetsma, A.; Petricek, V.; van Smaalen, Sander; Wiegers, G.A

    1995-01-01

    The inorganic misfit-layer compound (SbS)(1.15)TiS2 was prepared by high-temperature reaction of the elements. The structure, determined by single-crystal X-ray diffraction, is described by two interpenetrating incommensurately modulated subsystems. The first subsystem comprises TiS2 sandwiches, wit

  19. Development of compound layer during nitriding and nitrocarburising; current status and future challenges

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.

    2011-01-01

    diffusion and desorption or the competition with a carburising reaction. During compound layer growth, the nitriding kinetics is determined by a combination of solid state diffusion of interstitial elements and the kinetics of the surface reactions. Moreover, phase transformations within the compound layer...

  20. Local structure and defect chemistry of [(SnSe){sub 1.15}]{sub m}(TaSe{sub 2}) ferecrystals – A new type of layered intergrowth compound

    Energy Technology Data Exchange (ETDEWEB)

    Grosse, Corinna, E-mail: corinna.grosse@physik.hu-berlin.de [Department of Chemistry, University of Oregon, Eugene, OR 97401-3753 (United States); Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Atkins, Ryan, E-mail: atkins@uoregon.edu [Department of Chemistry, University of Oregon, Eugene, OR 97401-3753 (United States); Kirmse, Holm, E-mail: holm.kirmse@physik.hu-berlin.de [Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Mogilatenko, Anna, E-mail: anna.mogilatenko@fbh-berlin.de [Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Neumann, Wolfgang, E-mail: wsn@uoregon.edu [Department of Chemistry, University of Oregon, Eugene, OR 97401-3753 (United States); Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Johnson, David C., E-mail: davej@uoregon.edu [Department of Chemistry, University of Oregon, Eugene, OR 97401-3753 (United States)

    2013-12-05

    Highlights: •The crystal structure of [(SnSe){sub 1.15}]{sub m}(TaSe{sub 2}) ferecrystals was analyzed by TEM. •The layers exhibit turbostratic disorder, but we also observed a local ordering. •The structures of the SnSe and TaSe{sub 2} layers are similar to binary SnSe and 2H-TaSe{sub 2}. •An increasing in-plane SnSe grain size with increasing m was observed. •Defect areas with missing, substituted or additional layers were found. -- Abstract: The atomic structure of the family of ferecrystals [(SnSe){sub 1.15}]{sub m}(TaSe{sub 2}) (m = 1, 3, and 6) was investigated by means of transmission electron microscopy. The tantalum in the TaSe{sub 2} layers was observed to have trigonal prismatic coordination similar to that found in the 2H polytype of bulk TaSe{sub 2}. The structure of the SnSe constituent was found to be similar to that of orthorhombic α-SnSe. In the compounds with m = 1 and m = 3, regions with a local ordering of the layers along a commensurate axis, similar to the ordering in conventional misfit layer compounds, were observed. However, on a longer range the ferecrystals were found to exhibit a turbostratically disordered structure. Stacking defects were occasionally found in the samples in which a layer is interrupted and the surrounding layers are bent around these defects, while maintaining abrupt interfaces instead of interdiffusing. Volume defects were found in one sample of [(SnSe){sub 1.15}]{sub 1}(TaSe{sub 2}){sub 1} in which a SnSe layer locally substitutes a part of a TaSe{sub 2} layer without interrupting the surrounding layers.

  1. Functional Requirements and Layers of Protection for Compounds

    NARCIS (Netherlands)

    Oosterhout, A.W.G. van; Wevers, J.

    2010-01-01

    The compounds that are used during out-of-area operations serve a host of goals of which protection is one. They should be approached as integrated systems that are designed (and upgraded) according to the rules that also apply for other systems. The design of a compound contains two distinctive

  2. Multi-layer perception approach to identification of compound information

    Institute of Scientific and Technical Information of China (English)

    孙金玮; 李德胜

    2001-01-01

    Presents a novel approach of multi-layer sensing for perception of high-level environmental information related to many conventional physical quantities, such as temperature, humidity and brightness, which focuses on the processing of multi-functional variables in a multi-layer framework, and consists of multi-functional sensing and multi-layer fusion. Concerning the first aspect, a CdS and Fe3 O4 materials based multi-functionsensor has been developed to measure the three quantities, and provides a possible solution to the sensor multifunctional measurement equations, especially when the sensor processes more than three quantities, and proposes ways to evaluate the concerned environment as degree of comfort, Quantity Creditability Tactics (QCT) of multi-layer data fusion.

  3. Development of compound layer of iron (carbo)nitrides during nitriding of steel

    DEFF Research Database (Denmark)

    Ratajski, J.; Tacikowski, J.; Somers, Marcel A.J.

    2003-01-01

    The composition and phase constitution of a compound layer developing during gaseous nitriding was investigated at 853 K for three commercial steels (AISI 120, 4340 and 1090) and Armco iron. The compound layers were characterised by light optical microscopy, X-ray diffraction and electron probe...... microanalysis. The formation of the compound layer occurs along two distinct sequences: alpha-gamma prime-epsilon and/or alpha(theta)-epsilon2-gamma prime-epsilon1. The preferred sequence depends mainly on the chemical composition of steel and on the nitriding potential....

  4. Development of compound layer of iron (carbo)nitrides during nitriding of steel

    DEFF Research Database (Denmark)

    Ratajski, J.; Tacikowski, J.; Somers, Marcel A.J.

    2003-01-01

    The composition and phase constitution of a compound layer developing during gaseous nitriding was investigated at 853 K for three commercial steels (AISI 120, 4340 and 1090) and Armco iron. The compound layers were characterised by light optical microscopy, X-ray diffraction and electron probe...... microanalysis. The formation of the compound layer occurs along two distinct sequences: alpha-gamma prime-epsilon and/or alpha(theta)-epsilon2-gamma prime-epsilon1. The preferred sequence depends mainly on the chemical composition of steel and on the nitriding potential....

  5. Misfits in Organization Design: Information Processing as a Compensatory Mechanism

    Directory of Open Access Journals (Sweden)

    Ben Nanfeng Luo

    2013-04-01

    Full Text Available We propose a compensatory misfits theory which holds that an “over-fitting” organization structure can compensate for an “under-fitting” structure, thereby reducing the total misfit. In organizations, over-fit occurs when structural features misfit the core contingencies because the structural level is too high to fit the contingencies. An under-fit occurs when structural features misfit the contingencies because the structural level is too low. When an under-fit is compensated by an over-fit, the combination can produce performance outcomes that approximate those from fit. The reason inheres in information processing being a higher level factor that cuts across different contingencies and structural features that are mis-fitted to each other, so that compensation is possible. We identify the specific conditions that must be fulfilled for compensation to occur, and we discuss implications for organization design theory and practice.

  6. VARIOUS REGIMES OF CHARGE-DENSITY WAVES IN LAYERED COMPOUNDS

    NARCIS (Netherlands)

    Bakel, G.P.E.M. van; Hosson, J.Th.M. De

    1992-01-01

    In this paper we have subjected different layered transition-metal dichalcogenides to scanning tunneling microscopy to reveal the electronic charge distribution associated with the charge-density-wave (CDW) part of the superstructure, in addition to the atomic corrugation. The observations presented

  7. Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells.

    Science.gov (United States)

    Park, Keunhee; Oh, Seungsik; Jung, Donggeun; Chae, Heeyeop; Kim, Hyoungsub; Boo, Jin-Hyo

    2012-01-09

    We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure. For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + 66-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively. The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer. The current density-voltage characteristics of OSCs with an interfacial layer thickness of 0.7 nm and of those without an interfacial layer showed power conversion efficiency [PCE] values of 2.96% and 2.34%, respectively, under an illumination condition of 100 mW/cm2 (AM 1.5). It is thought that a cathode interfacial layer of an appropriate thickness enhances the electron transfer between the active layer and the cathode, and thus increases the PCE of the OSCs.

  8. Cooperative dissociations of misfit dislocations at bimetal interfaces

    Directory of Open Access Journals (Sweden)

    K. Liu

    2016-11-01

    Full Text Available Using atomistic simulations, several semi-coherent cube-on-cube bimetal interfaces are comparatively investigated to unravel the combined effect of the character of misfit dislocations, the stacking fault energy difference between bimetal pairs, and their lattice mismatch on the dissociation of interfacial misfit dislocations. Different dissociation paths and features under loadings provide several unique deformation mechanisms that are critical for understanding interface strengthening. In particular, applied strains can cause either the formation of global interface coherency by the migration of misfit dislocations from an interface to an adjoining crystal interior or to an alternate packing of stacking faults connected by stair-rod dislocations.

  9. Cooperative dissociations of misfit dislocations at bimetal interfaces

    Science.gov (United States)

    Liu, K.; Zhang, R. F.; Beyerlein, I. J.; Chen, X. Y.; Yang, H.; Germann, T. C.

    2016-11-01

    Using atomistic simulations, several semi-coherent cube-on-cube bimetal interfaces are comparatively investigated to unravel the combined effect of the character of misfit dislocations, the stacking fault energy difference between bimetal pairs, and their lattice mismatch on the dissociation of interfacial misfit dislocations. Different dissociation paths and features under loadings provide several unique deformation mechanisms that are critical for understanding interface strengthening. In particular, applied strains can cause either the formation of global interface coherency by the migration of misfit dislocations from an interface to an adjoining crystal interior or to an alternate packing of stacking faults connected by stair-rod dislocations.

  10. Dielectric barrier discharge ionization in characterization of organic compounds separated on thin-layer chromatography plates.

    Science.gov (United States)

    Cegłowski, Michał; Smoluch, Marek; Babij, Michał; Gotszalk, Teodor; Silberring, Jerzy; Schroeder, Grzegorz

    2014-01-01

    A new method for on-spot detection and characterization of organic compounds resolved on thin layer chromatography (TLC) plates has been proposed. This method combines TLC with dielectric barrier discharge ionization (DBDI), which produces stable low-temperature plasma. At first, the compounds were separated on TLC plates and then their mass spectra were directly obtained with no additional sample preparation. To obtain good quality spectra the center of a particular TLC spot was heated from the bottom to increase volatility of the compound. MS/MS analyses were also performed to additionally characterize all analytes. The detection limit of proposed method was estimated to be 100 ng/spot of compound.

  11. Thermoelectric Power In Misfit Cobaltites Ceramics: Optimization By Chemical Substitutions

    Directory of Open Access Journals (Sweden)

    Maignan, A.

    2006-06-01

    Full Text Available The ceramics of misfit cobaltites form a large family of layer oxides which exhibit large values of Seebeck coefficient (S300K ≥90μV.K-1. They can be divided in two categories depending on the number of the rocksalt-type (RS layers, n = 3 or n = 4, separating the [CoO2] conducting layers. From the comparison of their structural features, it is found that the S values are governed by the incommensurability ratio and/or the charge of the RS block. This is clearly evidenced by making chemical substitutions at the level of the RS block: isovalent but with cations of different ionic radius (rBa 2+ > rSr 2+ > rCa 2+ modifying the incommensurability ratio or aliovalent substitutions for cobalt (Pb4+, Ti4+ which keep unchanged the structural incommensurability but make the RS charge changing.

    Las cerámicas basadas en cobaltitas forman una extensa familia de óxidos que presentan valores elevados del coeficiente seebeck (S300k ≥90 μV.K-1. Se pueden dividir en dos grupos dependiendo del número de capas con estructura de cloruro sódico (rocksalt - RS, n=3 ó n=4, que separan las capas conductoras de [CoO2] . Comparando sus caractetísticas estructurales, se ha encontrado que los valores de S están gobernados por la relación de inconmensurabilidad y la carga del bloque con estructura RS. Esto se evidencia claramente realizando sustituciones químicas en los bloques RS: Isobalentes con cationes de diferente radio (rBa 2+ > rSr 2+ > rCa 2+ que modifican la relación de inconmensurabilidad o sustituciones aliovalentes de cobalto (Pb4+, Ti4+ que provocan cambios en la carga del bloque RS pero no en la inconmensurabilidad.

  12. In Situ Synthesis of Nanocrystalline Intermetallic Compound Layer during Surface Mechanical Attrition Treatment of Zirconium

    Institute of Scientific and Technical Information of China (English)

    SUNCai-yun; XIEJi-jia; WUXiao-lei; HONGYou-shi; LIUGang; LUJian; LUKe

    2004-01-01

    The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, 1.5Cr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25μm thick and consisted of the intermetallic compound FeCr with an average grain size of 25+10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.

  13. Microstructural and Phase Evolution of Compound Layers Growing on α-Iron During Gaseous Nitrocarburizing

    Science.gov (United States)

    Woehrle, T.; Leineweber, A.; Mittemeijer, E. J.

    2012-07-01

    The microstructural evolution of compound layers grown on 1-mm thick α-iron substrates after nitrocarburizing at 853 K (580 °C) in NH3/H2/N2/CO gas mixtures was investigated by light optical microscopy and X-ray diffraction. The evolution of the microstructure can be divided into several stages. Starting with the formation of the carbon-rich phase cementite, which practically does not contain nitrogen, the phase constitution of the compound layer develops through successive stages of microstructural change into the direction of the nitrogen-richer and carbon-poorer phases ɛ and γ'. These results are the consequences of (1) the kinetics of nitrogen and carbon uptake at the gas-solid interface and the considerably different solubilities of nitrogen and carbon in the α-iron substrate and (2) the occurrence of local equilibrium conditions prevailing at the solid-solid interphase boundaries in the compound layer. The change of the microstructure as a function of depth in the compound layer is shown to be compatible with so-called "diffusion paths" in the ternary Fe-N-C phase diagram.

  14. Electrospun nanofiber layers with incorporated photoluminescence indicator for chromatography and detection of ultraviolet-active compounds.

    Science.gov (United States)

    Kampalanonwat, Pimolpun; Supaphol, Pitt; Morlock, Gertrud E

    2013-07-19

    For the first time, electrospun nanofiber phases were fabricated with manganese-activated zinc silicate as photoluminescent indicator (UV254) to transfer and enlarge its application to the field of UV-active compounds. By integration of such an indicator, UV-active compounds got visible on the chromatogram. The separation of 7 preservatives and a beverage sample were studied on the novel luminescent polyacrylonitrile layers. The mat thickness and mean fiber diameters were calculated for additions of different UV254 indicator concentrations. The separation efficiency on the photoluminescent layers was characterized by comparison to HPTLC layers and calculation of the plate numbers and resolutions. Some benefits were the reduction in migration distance (3cm), migration time (12min), analyte (10-nL volumes) and mobile phase volumes (1mL). As ultrathin stationary phase, such layers are suited for their integration into the Office Chromatography concept. For the first time, electrospun nanofiber layers were hyphenated with mass spectrometry and the confirmation of compounds was successfully performed using the elution-head based TLC-MS Interface.

  15. Effects of surface reconstruction on the epitaxial growth of III-Sb on GaAs using interfacial misfit array

    Science.gov (United States)

    Jia, Bo Wen; Tan, Kian Hua; Loke, Wan Khai; Wicaksono, Satrio; Yoon, Soon Fatt

    2017-03-01

    The effects of pre-growth Sb reconstruction on a GaAs surface on the epitaxial growth of III-Sb (GaSb and InSb) on a (100) GaAs substrate using interfacial misfit array were investigated. All samples exhibited smooth surface with a root mean square (r.m.s.) roughness below 1.5 nm and nearly 100% relaxation. Modeling indicated that the distribution and types of misfit dislocations can be evaluated using a reciprocal space map (RSM) of the x-ray measurements. The interfacial misfit (IMF) arrays in III-Sb/GaAs samples were characterized by RSMs of high-resolution x-ray diffraction (XRD) and transmission electron microscopy (TEM). The RSM results suggest that all samples exhibited highly uniformly distributed misfit dislocations, and pre-growth (2 × 8) Sb surface reconstruction promoted the formation of 90° dislocations in an IMF array. Hall measurements of unintentionally doped GaSb and InSb layers also suggested that the highest motilities at both 77 K and 300 K were achieved at the samples grown on GaAs with pre-growth (2 × 8) Sb reconstruction.

  16. Threading and misfit-dislocation motion in molecular-beam epitaxy-grown HgCdTe epilayers

    Science.gov (United States)

    Carmody, M.; Lee, D.; Zandian, M.; Phillips, J.; Arias, J.

    2003-07-01

    Lattice mismatch between the substrate and the absorber layer in single-color HgCdTe infrared (IR) detectors and between band 1 and band 2 in two-color detectors results in the formation of crosshatch lines on the surface and an array of misfit dislocations at the epi-interfaces. Threading dislocations originating in the substrate can also bend into the interface plane and result in misfit dislocations because of the lattice mismatch. The existence of dislocations threading through the junction region of HgCdTe IR-photovoltaic detectors can greatly affect device performance. High-quality CdZnTe substrates and controlled molecular-beam epitaxy (MBE) growth of HgCdTe can result in very low threading-dislocation densities as measured by the etch-pit density (EPD ˜ 104cm-2). However, dislocation gettering to regions of high stress (such as etched holes, voids, and implanted-junction regions) at elevated-processing temperatures can result in a high density of dislocations in the junction region that can greatly reduce detector performance. We have performed experiments to determine if the dislocations that getter to these regions of high stress are misfit dislocations at the substrate/absorber interface that have a threading component extending to the upper surface of the epilayer, or if the dislocations originate at the cap/absorber interface as misfit dislocations. The preceding mechanisms for dislocation motion are discussed in detail, and the possible diode-performance consequences are explored.

  17. Misfit dislocation gettering by substrate pit-patterning in SiGe films on Si(001)

    Energy Technology Data Exchange (ETDEWEB)

    Grydlik, Martyna; Groiss, Heiko; Brehm, Moritz; Schaeffler, Friedrich [Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz (Austria); Boioli, Francesca; Montalenti, Francesco; Miglio, Leo [L-NESS and Department of Material Science, University of Milano-Bicocca (Italy); Gatti, Riccardo; Devincre, Benoit [LEM, CNRS/ONERA, Chatillon Cedex (France)

    2012-07-02

    We show that suitable pit-patterning of a Si(001) substrate can strongly influence the nucleation and the propagation of dislocations during epitaxial deposition of Si-rich Si{sub 1-x}Ge{sub x} alloys, preferentially gettering misfit segments along pit rows. In particular, for a 250 nm layer deposited by molecular beam epitaxy at x{sub Ge} = 15%, extended film regions appear free of dislocations, by atomic force microscopy, as confirmed by transmission electron microscopy sampling. This result is quite general, as explained by dislocation dynamics simulations, which reveal the key role of the inhomogeneous distribution in stress produced by the pit-patterning.

  18. New materials for optoelectronic devices: Growth and characterization of indium and gallium chalcogenide layer compounds

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, A.M.; Micocci, G.; Rizzo, A.

    1983-09-01

    The main characteristics and the possible applications of some new materials for optoelectronic devices are analyzed. For this purpose, the most widely used growth methods for obtaining good quality single crystals of indium and gallium chalcogenide layered compounds are described together with the best results obtained by us in the growth of GaS, GaSe, GaTe and InSe. The structural characteristics of these compounds, as inferred by electron and X-ray diffraction are reported. The electrical and optical properties of the various materials are related to the growth methods and are analyzed taking into account the trapping centers present in the energy gaps. The parameters of these centers are reported for all the analyzed layered compounds as determined by different electric and photoelectric techniques.

  19. Microcantilever sensors coated with a sensitive polyaniline layer for detecting volatile organic compounds.

    Science.gov (United States)

    Steffens, C; Leite, F L; Manzoli, A; Sandovall, R D; Fatibello, O; Herrmann, P S P

    2014-09-01

    This paper describes a silicon cantilever sensor coated with a conducting polymer layer. The mechanical response (deflection) of the bimaterial (the coated microcantilever) was investigated under the influence of several volatile compounds-methanol, ethanol, acetone, propanol, dichloroethane, toluene and benzene. The variations in the deflection of the coated and uncoated microcantilevers when exposed to volatile organic compounds were evaluated, and the results indicated that the highest sensitivity was obtained with the coated microcantilever and methanol. The uncoated microcantilever was not sensitive to the volatile organic compounds. An increase in the concentration of the volatile organic compound resulted in higher deflections of the microcantilever sensor. The sensor responses were reversible, sensible, rapid and proportional to the volatile concentration.

  20. Microstructural and compositional evolution of iron carbonitride compound layers during salt bath nitrocarburizing

    Energy Technology Data Exchange (ETDEWEB)

    Somers, M.A.J.; Colijn, P.F.; Sloof, W.G.; Mittemeijer, E.J. (Technische Hogeschool Delft (Netherlands). Lab. of Metallurgy)

    1990-01-01

    An analysis was made of iron carbonitride compound layer development during nitrocarburizing of pure iron and two iron-carbon specimens, containing 0.3 wt.-% C and 0.6 wt.-% C, respectively, in an aerated cyanate-based salt bath at 853 K. The microstructural evolution was followed by means of light- and scanning electron microscopy and X-ray diffraction analysis. Composition-depth profiles were determined as a function of nitrocarburizing time applying electron-probe microanalysis and X-ray diffraction analysis. Compound layer formation on pure iron starts with the nucleation of cementite at the surface, which is immediately followed by nucleation of {epsilon} carbonitride containing a relatively high carbon content and a relatively low nitrogen content. Thereafter, {gamma}' (carbo)nitride and finally {epsilon} nitride develop at the outer surface. In general, on continued nitrocarburizing the nitrogen content at the outer surface increases and the carbon content decreases. Accordingly, the constitution of the compound layer is determined to a large extent by the (difference between the) absorption kinetics of carbon and of nitrogen rather than by equilibrium thermodynamics. In the surface-adjacent region, the layers are highly porous, predominantly as a consequence of corrosive attack by agents of the salt bath. As compared with nitrocarburizing of pure iron, the major effect of carbon present as cementite in pearlite regions in the iron-carbon specimens appears to be promotion of the formation of {epsilon} carbonitride in the compound layer at the cost of {gamma}' (carbo)nitride. (orig.).

  1. Intermetallic compound layer growth kinetics in non-lead bearing solders

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T.; Kilgo, A.C.; Grant, R.

    1995-04-01

    The introduction of alternative, non-lead bearing solders into electronic assemblies requires a thorough investigation of product manufacturability and reliability. Both of these attributes can be impacted by the excessive growth of intermetallic compound (IMC) layers at the solder/substrate interface. An extensive study has documented the stoichiometry and solid state growth kinetics of IMC layers formed between copper and the lead-free solders: 96.5Sn-3.5Ag (wt.%), 95Sn-5Sb, 100Sn, and 58Bi-42Sn. Aging temperatures were 70--205 C for the Sn-based solders and 55--120 C for the Bi-rich solder. Time periods were 1--400 days for all of the alloys. The Sn/Cu, Sn-Ag/Cu, and Sn-Sb/Cu IMC layers exhibited sub-layers of Cu{sub 6}Sn{sub 5} and Cu{sub 3}Sn; the latter composition was present only following prolonged aging times or higher temperatures. The total layer growth exhibited a time exponent of n = 0.5 at low temperatures and a value of n = 0.42 at higher temperatures in each of the solder/Cu systems. Similar growth kinetics were observed with the low temperature 58Bi-42Sn solder; however, a considerably more complex sub-layer structure was observed. The kinetic data will be discussed with respect to predicting IMC layer growth based upon solder composition.

  2. The Misfits : kuulsad kollid. Rosta Aknad avanevad. Indie tuleb, indie tapab!

    Index Scriptorium Estoniae

    2006-01-01

    9.-10. juunil Järvakandis toimuval festivalil Rabarock esinevatest ansamblitest: The Misfits, Rosta Aknad, The Cooper Temple Clause (vt. www. rabarock. ee, www.misfits.com, www.thecoopertempleclause.co.uk)

  3. The Misfits : kuulsad kollid. Rosta Aknad avanevad. Indie tuleb, indie tapab!

    Index Scriptorium Estoniae

    2006-01-01

    9.-10. juunil Järvakandis toimuval festivalil Rabarock esinevatest ansamblitest: The Misfits, Rosta Aknad, The Cooper Temple Clause (vt. www. rabarock. ee, www.misfits.com, www.thecoopertempleclause.co.uk)

  4. TEM investigation of the as-quenched compound layer formed by austenitic nitrocarburizing

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Y.; Wang, Y.; Hu, G.; Chen, X. [Shanghai Jiao Tong Univ. (China)

    1998-07-01

    The as-quenched compound layer of a 0.2% C steel formed by austenitic nitrocarburizing is found to be composed of single-phase {epsilon}-nitrocarbide with an hexagonal structure, as determined by electron diffraction. The difference in the site occupancy of nitrogen or carbon atoms may result in the formation of various types of {epsilon}-nitrocarbide; that is, {epsilon}-Fe{sub 2}(N,C), {epsilon}-Fe{sub 2{center_dot}3}(N,C), and {epsilon}-Fe{sub 3}(N,C). By a comparison of the intensities of the superlattice reflection spots observed in the electron diffraction patterns with those in computed simulation patterns, the phase in the compound layer of the as-quenched sample was identified as {epsilon}-Fe{sub 2{center_dot}3}(N,C).

  5. Job-Occupation Misfit as an Occupational Stressor

    Science.gov (United States)

    Ford, Michael T.

    2012-01-01

    Drawing from theory on met expectations, person-environment fit, and social information processing, misfit between the pressure and autonomy experienced by workers and that which would be expected given their occupational roles was examined as a predictor of job satisfaction, perceived support, and depression. Results from a nationally (U.S.)…

  6. Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

    OpenAIRE

    Kagan, Isabelle A.; Flythe, Michael D.

    2014-01-01

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken wit...

  7. Preparation and Characterization of Layered Compound Zirconium Bis(monohydrogenphosphate) Intercalated with Rare Earth Complex

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Layered compound zirconium bis(monohydrogenphosphate)(α -ZrP) intercalated with rare earth complex Eu(DBM)3phen was prepared. The pre-intercalation of p-methoxyaniline into α -ZrP makes the interlayer separation large enough to exchange PMA with europium complex, thus, the luminescent assembly was prepared. This was confirmed by X-ray diffraction, UV-visible spectra and elemental analysis. The fluorescence spectra and lifetime of the assembly were also presented.

  8. Thickness of compound layer in steel-aluminum solid to liquid bonding

    Institute of Scientific and Technical Information of China (English)

    Peng Zhang; Yunhui Du; Hanwu Liu; Shuming Xing; Daben Zeng; Jianzhong Cui; Limin Ba

    2003-01-01

    The bonding of solid steel plate to liquid aluminum was studied using rapid solidification. The surface of solid steel plate was defatted, descaled, immersed (in K2ZrF6 flux aqueous solution) and stoved. In order to determine the thickness of Fe-A1 compound layer at the interface of steel-aluminum solid to liquid bonding under rapid solidification, the interface of bonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationship between bonding parameters (such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time) and thickness of Fe-Al compound layer at the interface was established by artificial neural networks (ANN) perfectly. The maximum of relative error between the output and the desired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacial shear strength of bonding plate (226℃ for preheat temperature of steel plate, 723 ℃ for temperature of aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-A1 compound layer 10.8 μm was got.

  9. A novel method to get methotrexatum/layered double hydroxides intercalation compounds and their release properties

    Science.gov (United States)

    Qi, Fenglin; Zhang, Xiaoqing; Li, Shuping

    2013-08-01

    In this context, the methotrexatum/layered double hydroxides (MTX/LDHs) intercalation compounds have been synthesized by a mechanochemical-hydrothermal method, which involves a grinding process and subsequent hydrothermal treatment. The influence of R (molar ratio of Mg2+ to Al3+ to MTX) values on the structure and morphology of the intercalation compounds and their release properties were investigated systematically. The resulting compounds were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), inductively coupled plasma (ICP), thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. All the results indicate that R value has significant influence on the intercalation of MTX anions into LDH interlayer and the optimal R value is 2:1:0.5. Furthermore, four dissolution-diffusion kinetic models were used to fit the in vitro release of MTX from LDH layers. The release process can be divided into two stages: firstly surface diffusion and secondly intraparticle diffusion. The study also revealed that the properties of the intercalation compounds is comparable to that obtained from standard methods such as co-precipitation method, but with time, solvent and energy saving.

  10. Synthesis, structure, and properties of a novel family of layered transition nitride compounds

    Science.gov (United States)

    Weil, Kenneth Scott

    The chemical properties of nitrogen present a number of difficulties in the synthesis of nitride compounds. Most of these compounds have small free energies of formation due in part to the strong triple bond of N2. Thus the standard solid state approach of synthesizing compounds from a mixture of their constituents at high reaction temperatures is generally precluded. A general alternative to solid state synthesis is the molecularly mixed precursor route. The primary advantage of this approach is the control of composition. This concept has been demonstrated in this study through the use of a nonaqueous, complexed co-precipitation technique to synthesize a number of new ternary nitride compounds, including the a new nitride phase, CrWN2, and four series of substitutional variations of this compound, as wen as twelve additional new compounds crystallizing in the layered dinitride, eta-nitride, and pi-nitride crystal structures. The layered nitride, CrWN2, is the focal point of this thesis. The details of its crystal and defect structure, synthesis, properties, and substitutional chemistry have been examined and discussed within. Briefly, this compound crystallizes in a trigonal structure and consists of alternating layers of chromium in octahedral coordination with nitrogen and tungsten in trigonal prismatic coordination with nitrogen. Microstructurally, the nitride frequently displays twinning and the formation of coherent rock salt structured intergrowth defects. As mentioned above, the layered nitride evolves from a co-precipitated precursor; a fine mixture of [Cr(NH3)6]Cl 2 and WOCl2·3NH3. Upon heat treatment in an ammonia atmosphere, the two transition metal complexes separately decompose into their non-complexed chloride state, i.e. CrCl2 and WOCl 2, before reacting with each other and the ambient ammonia atmosphere between 420°C and 570°C to form a glassy oxynitrochloride phase, CrWO 1.01N0.36Cl2.45. Around 600°C, this compound undergoes ammonolysis

  11. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    Science.gov (United States)

    Smirnov, A. M.; Young, E. C.; Bougrov, V. E.; Speck, J. S.; Romanov, A. E.

    2016-01-01

    We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ˜70° for Al0.13Ga0.87N/GaN ( h 0 h ¯ 1 ) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1-xN/GaN heterostructures.

  12. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    KAUST Repository

    Smirnov, A. M.

    2016-01-20

    We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN (h0h̄ 1) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

  13. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    Directory of Open Access Journals (Sweden)

    A. M. Smirnov

    2016-01-01

    Full Text Available We calculate the critical thickness for misfit dislocation (MD formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs. It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN ( h 0 h ̄ 1 semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

  14. Propagation of misfit dislocations from buffer/Si interface into Si

    Science.gov (United States)

    Liliental-Weber, Zuzanna [El Sobrante, CA; Maltez, Rogerio Luis [Porto Alegre, BR; Morkoc, Hadis [Richmond, VA; Xie, Jinqiao [Raleigh, VA

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  15. Boundary layer concentrations and landscape scale emissions of volatile organic compounds in early spring

    Directory of Open Access Journals (Sweden)

    S. Haapanala

    2007-01-01

    Full Text Available Boundary layer concentrations of several volatile organic compounds (VOC were measured during two campaigns in springs of 2003 and 2006. The measurements were conducted over boreal landscapes near SMEAR II measurement station in Hyytiälä, Southern Finland. In 2003 the measuremens were performed using a light aircraft and in 2006 using a hot air balloon. Isoprene concentrations were low, usually below detection limit. This can be explained by low biogenic production due to cold weather, phenological stage of the isoprene emitting plants, and snow cover. Monoterpenes were observed frequently. The average total monoterpene concentration in the boundary layer was 33 pptv. Many anthropogenic compounds such as benzene, xylene and toluene, were observed in high amounts. Ecosystem scale surface emissions were estimated using a simple mixed box budget methodology. Total monoterpene emissions varied up to 80 μg m−2 h−1, α-pinene contributing typically more than two thirds of that. These emissions were somewhat higher that those calculated using emission algorithm. The highest emissions of anthropogenic compounds were those of p/m xylene.

  16. Transformation and Deposition of Sulphur and Nitrogen Compounds in the Marine Boundary Layer

    Energy Technology Data Exchange (ETDEWEB)

    Hertel, O.

    1995-10-01

    In this thesis the author performs a model study of the transformation and deposition of sulphur and nitrogen compounds in the marine boundary layer, including source-receptor relationships. The central part of the study is the development and testing of a variable scale trajectory model for Europe, with special emphasis on modelling the concentrations of gases and aerosols in the marine atmosphere and the deposition to sea. A one-dimensional version of the model was developed to model the chemical degradation of dimethyl sulphide (DMS) in the marine boundary layer. Although the model reproduces the observed levels of DMS and methane sulphonic acid (MSA) well, the calculated DMS concentration is not always in phase with observed levels, probably because of a local coastal emission that is correlated with the shifting tide. Another version of the trajectory model, Atmospheric Chemistry and Deposition model (ACDEP), was developed to study the deposition of nitrogen compounds to the Danish sea waters. This model uses a new numerical scheme, the Eulerian Backward Iterative method. The model is able to reproduce observations of air concentrations and wet deposition fairly well; data for dry deposition were not available. The model was also used for calculation of deposition of nitrogen compounds to the Kattegat. Finally, a sensitivity study was performed on the model. 175 refs., 87 figs., 32 tabs.

  17. Misfit strain phase diagrams of epitaxial PMN–PT films

    Energy Technology Data Exchange (ETDEWEB)

    Khakpash, N.; Khassaf, H.; Rossetti, G. A. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Alpay, S. P., E-mail: p.alpay@ims.uconn.edu [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2015-02-23

    Misfit strain–temperature phase diagrams of three compositions of (001) pseudocubic (1 − x)·Pb (Mg{sub l/3}Nb{sub 2/3})O{sub 3} − x·PbTiO{sub 3} (PMN–PT) thin films are computed using a phenomenological model. Two (x = 0.30, 0.42) are located near the morphotropic phase boundary (MPB) of bulk PMN–PT at room temperature (RT) and one (x = 0.70) is located far from the MPB. The results show that it is possible to stabilize an adaptive monoclinic phase over a wide range of misfit strains. At RT, the stability region of this phase is much larger for PMN–PT compared to barium strontium titanate and lead zirconate titanate films.

  18. Misfit strain phase diagrams of epitaxial PMN-PT films

    Science.gov (United States)

    Khakpash, N.; Khassaf, H.; Rossetti, G. A.; Alpay, S. P.

    2015-02-01

    Misfit strain-temperature phase diagrams of three compositions of (001) pseudocubic (1 - x).Pb (Mgl/3Nb2/3)O3 - x.PbTiO3 (PMN-PT) thin films are computed using a phenomenological model. Two (x = 0.30, 0.42) are located near the morphotropic phase boundary (MPB) of bulk PMN-PT at room temperature (RT) and one (x = 0.70) is located far from the MPB. The results show that it is possible to stabilize an adaptive monoclinic phase over a wide range of misfit strains. At RT, the stability region of this phase is much larger for PMN-PT compared to barium strontium titanate and lead zirconate titanate films.

  19. Efficient inverted polymer solar cells integrated with a compound electron extraction layer

    Science.gov (United States)

    Ma, Zhong-Sheng; Wang, Qian-Kun; Li, Chi; Li, Yan-Qing; Zhang, Dan-Dan; Liu, Weimin; Wang, Pengfei; Tang, Jian-Xin

    2015-12-01

    We constructed an effective electron extraction layer (EEL) used for polymer solar cells by integrating one new kind of organic material of 4,4‧-(1,4-phenylene) bis(2-phenyl-6-p-tolylnicotinonitrile) (p-PPtNT) and cesium carbonate (Cs2CO3) used as a compound EEL (CEEL). The CEEL based device exhibits an ideal PCE of 4.15%, corresponding to an enhancement 220% in contrast to that of control device without EEL, which is also comparable to that of ZnO based device. Our analyses indicated that the remarkably improved PCE for CEEL based device is mainly ascribed to the Ohmic contact and the negligible electron extraction barrier at cathode/active layer by inserting CEEL.

  20. Radiographic diagnosis of dental restoration misfit: a systematic review.

    Science.gov (United States)

    Liedke, G S; Spin-Neto, R; da Silveira, H E D; Wenzel, A

    2014-12-01

    The objective of this study was to perform a systematic review on the use of radiographic methods for the diagnosis of misfit in dental prostheses and restorations. The MEDLINE bibliographic database was searched from 1950 to February 2014 for reports on the radiographic diagnosis of misfits. The search strategy was limited to English-language publications using the following combined MeSH terms in the search strategy: (Dental Restoration OR Dental Prosthesis OR Crown OR Inlays OR Dental Abutments) and (Dental Leakage OR Prosthesis Fitting OR Dental Marginal Adaptation OR Surface Properties) and (Radiography, Dental OR Radiography, Dental, Digital OR Cone-Beam Computed Tomography). Twenty-eight publications were identified and read in full text, and 14 studies fulfilled criteria for inclusion. Information regarding the use of radiographic methods for the diagnosis of misfits in dental prosthesis and restorations, and in which the methodology/results comprised information regarding how the sample was collected/prepared, the method, imaging protocol, presence of a reference test and the outcomes were evaluated. QUADAS criteria was used to rate the studies in high, moderate or low quality. The evidence supporting the use of radiographic methods for the diagnosis of misfits in dental prosthesis and restorations is limited to low-/moderate-quality studies. The well-established intra-oral orthogonal projection is still under investigation and considered the most appropriate method, both when evaluating the relation between dental restoration to tooth and abutment to implant. Studies using digital radiographs have not evaluated the effect of image post-processing, and tomography has not been evaluated.

  1. Weak localization effects in Ga-intercalated layered compound NbS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Niazi, A. [Jawaharlal Nehru Univ., New Delhi (India). School of Physical Science; Rastogi, A.K. [Jawaharlal Nehru Univ., New Delhi (India). School of Physical Science

    1996-07-01

    Ga{sub x}NbS{sub 2}(x=0-0.33) was prepared in two batches-{proportional_to}1000 C (LT) and {proportional_to}1125 C (HT). X-ray diffraction shows random stacking of 2H-NbS{sub 2} layers in the HT phase. Resistivity and thermopower measurements from 15 to 300 K show metallic behaviour and anomalies around 45 K. The disordered phases indicate weak localisation effects in conductivity above 45 K and a log T variation in the x=0.25 compound indicating 2-D conduction. The thermopower is unaffected by the disorder. The 45 K transition suppresses this localisation. (orig.).

  2. The Europeanisation of Austria: Misfit, Adaptation and Controversies

    Directory of Open Access Journals (Sweden)

    Gerda Falkner

    2001-12-01

    Full Text Available This article analyses the multiple dimensions of Austrias Europeanisation and the high degree of both misfit and conflict involved therein. Austrias path to EU membership was characterised by fundamental doubts due to the countrys status of neutrality, and by a basic reinterpretation of this concept. After accession, need for institutional adaptation to the EUs decision-making patterns was significant since major tenets of the Austrian political system are special. Furthermore, policy misfit between the domestic and the EU level was considerable in several fields, among them highly symbolic ones. Austrias EU-related diplomacy recently witnessed a major crisis with the other 14 member states sanctioning the new centre-right government in a controversial way. Against this background of strong and multi-dimensional misfit, Austrian performance in implementing EU law is still surprisingly good. By contrast, public appreciation of EU membership has declined even further, and a majority of Austrians oppose enlargement while the Freedom Party advocates a referendum on that issue. Therefore, the conclusions argue that improved communication processes and mutual learning across the multiple levels of the EU system are crucial.

  3. The Europeanisation of Austria: Misfit, Adaptation and Controversies

    Directory of Open Access Journals (Sweden)

    Gerda Falkner

    2001-12-01

    Full Text Available This article analyses the multiple dimensions of Austria’s Europeanisation and the high degree of both misfit and conflict involved therein. Austria’s path to EU membership was characterised by fundamental doubts due to the country’s status of neutrality, and by a basic reinterpretation of this concept. After accession, need for institutional adaptation to the EU’s decision-making patterns was significant since major tenets of the Austrian political system are special. Furthermore, policy misfit between the domestic and the EU level was considerable in several fields, among them highly symbolic ones. Austria’s EU-related diplomacy recently witnessed a major crisis with the other 14 member states ‘sanctioning’ the new centre-right government in a controversial way. Against this background of strong and multi-dimensional misfit, Austrian performance in implementing EU law is still surprisingly good. By contrast, public appreciation of EU membership has declined even further, and a majority of Austrians oppose enlargement while the Freedom Party advocates a referendum on that issue. Therefore, the conclusions argue that improved communication processes and mutual learning across the multiple levels of the EU system are crucial.

  4. Thermodynamics, Kinetics and Microstructural Evolution of the Compound Layer; a Comparison of the States of Knowledge of Nitriding and Nitrocarburising

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.

    2000-01-01

    on the steel surface are sufficiently high, a compound layer is formed at the surface of a ferritic steel, which consists predominantly of ? and/or ?' phases. In the region underneath the compound layer, the so-called diffusion zone develops. The compound layer has an interesting combination of wear...... conditions for tailoring a certain combination of properties. The present paper describes aspects of the thermodynamics, kinetics and microstructure evolution of the compound layer on pure iron during nitrocarburising, by comparing the current status of qualitative understanding with that for nitriding......, which is largely quantitative. Iron was taken as a model case in order to assess the actual effect of the interstitial elements nitrogen and carbon provided by the nitriding and nitrocarburising gases....

  5. Microstructural behavior of nitriding compound layer for Nb-carbonitride coating grown by thermo-reactive diffusion process

    Science.gov (United States)

    Lee, Kyunghoon; Kang, Namhyun; Bae, Jong-Seong; Lee, Chang-Woo

    2016-09-01

    This study aims to understand the microstructural behavior of nitriding compound layer and its effect on Nb-carbonitride growth produced by the thermo-reactive diffusion (TRD) process. Gas nitriding was performed at 550 °C for 3 and 6 h, followed by TRD at 900 °C for 6 h. The nitriding compound layers had thicknesses of 10 and 16 μm for nitriding time of 3 and 6 h, respectively. The corresponding Nb-carbonitride layers produced by TRD were 7.2 and 11.2 μm thick, respectively. Reheating at 900 °C transformed the microstructure of the nitriding compounds to Fe3O4 and FeN0.0939. As reheating proceeded to 30 min, high concentration of nitrogen, initially existing in the nitride layer diffused to 80-90 μm into the substrate. Therefore, the TRD process produced NbN layer at the interfacial area due to intensively dissolved nitrogen from FeN0.0939. As the TRD proceeded, supply of C atoms from the base metal became competitive with the N diffusion. Thus, the TRD coating layer was grown to above the interface. Reheating at 900 °C for the 16-μm-thick nitride layer resulted in a nitrogen content ˜0.4 at% higher than that for the 10-μm-thick nitride layer, thereby producing a thicker Nb-carbonitride layer.

  6. Thermoelectric properties of the misfit cobaltate Ca3Co4O9

    Science.gov (United States)

    Amin, Bin; Eckern, Ulrich; Schwingenschlögl, Udo

    2017-06-01

    The layered misfit cobaltate Ca3Co4O9, also known as Ca2CoO3[CoO2]1.62, is a promising p-type thermoelectric oxide. Employing density functional theory, we study its electronic structure and determine, on the basis of Boltzmann theory within the constant-relaxation-time approximation, the thermoelectric transport coefficients. The dependence on strain and temperature is determined. In particular, we find that the xx-component of the thermopower is strongly enhanced, while the yy-component is strongly reduced, when applying 2% tensile strain. A similar anisotropy is also found in the power factor. The temperature dependence of the conductivity in the a-b plane is found to be rather weak above 200 K, which clearly indicates that the experimentally observed transport properties are dominated by inhomogeneities arising during sample growth, i.e., they are not intrinsic.

  7. Thermoelectric properties of the misfit cobaltate Ca3Co4O9

    KAUST Repository

    Amin, Bin

    2017-06-09

    The layered misfit cobaltate CaCoO, also known as CaCoO[CoO], is a promising p-type thermoelectric oxide. Employing density functional theory, we study its electronic structure and determine, on the basis of Boltzmann theory within the constant-relaxation-time approximation, the thermoelectric transport coefficients. The dependence on strain and temperature is determined. In particular, we find that the XX-component of the thermopower is strongly enhanced, while the yy-component is strongly reduced, when applying 2% tensile strain. A similar anisotropy is also found in the power factor. The temperature dependence of the conductivity in the a-b plane is found to be rather weak above 200 K, which clearly indicates that the experimentally observed transport properties are dominated by inhomogeneities arising during sample growth, i.e., they are not intrinsic.

  8. In Situ Synthesis of Titanium Nickel Intermetallic Compounds Layer and TiN Coating By Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cui-hong; YANG Yong-qiang; XU Wei-hong

    2006-01-01

    Laser cladding,together with laser nitriding was used to synthesize a titanium nickel intermetallic compound layer on the nickel substrate and a TiN coating on the cladding layer. During the laser cladding, Ti and Ni powders were blown into the melting pool by a six-hole coaxial nozzle powder injection system. Exothermic reactions between Ti and Ni took place in the melting pool, and a cladding layer of titanium nickel intermetallic compounds was produced. Laser nitriding in a nitrogen-rich atmosphere followed the production of the cladding layer, and formed a golden yellow TiN layer over it. An optical and a scanning electron microscope were used to investigate the microstructures and measure the thicknesses of the cladding layer and the TiN layer. Phase identification was carried out by XRD. For the nitriding sample, the microhardness profile of the clad layer was tested. The optimal process parameters of the in situ synthesis of titanium nickel intermetallic compounds were obtained.

  9. Experimental study on the effect of misfit and mismatch of ship plating welds

    OpenAIRE

    Bebermeyer, Robert E.

    2002-01-01

    CIVINS Approved for public release; distribution is unlimited Misfits and mismatches in the welding of ship hull plating may affect survivability after explosions, accidents, or other extreme external forces. Experiments, Slip Line Theory (SLT), and Finite Element Analysis (FEA) help to explain the necking, deformation, and mechanisms of fracture of misfit welded plating. The effect of misfits or offsets on both overmatched and evenmatched welds under tension are studied. The tension cr...

  10. Novel fluorinated compounds that improve durability of antistick layer for quartz mold

    Science.gov (United States)

    Yamashita, Tsuneo; Mitsuhashi, Hisashi; Morita, Masamichi; Iyoshi, Shuso; Okada, Makoto; Matsui, Shinji

    2014-03-01

    In recent years, the reduction in pattern size is driving the rapid adoption of nanoimprint lithography (NIL). Since nanoimprinting since is contact printing, a higher separation force might damage the master and/or the imprint tool, either of which degrades pattern quality. One of the biggest concerns in NIL utilization is the mold-release characteristic of the master and the resin. Although Optool DSXTM (DAIKIN Ind. Ltd.) is a de facto standard as mold release reagent, there is a problem with its UV-NIL durability. Accordingly, we focused on developing new fluorinated low molecular weight perfluorocompounds to enhance the mold-release characteristic of the resist. This paper reports that resists containing these fluroinated compounds offer improved durability as antistick layers for quartz molds subjected to repeated UV-NIL exposure.

  11. Thin-layer chromatographic (TLC) separations and bioassays of plant extracts to identify antimicrobial compounds.

    Science.gov (United States)

    Kagan, Isabelle A; Flythe, Michael D

    2014-03-27

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions. This paper describes standard protocols for TLC and contact bioautography with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light. Zones are cut out and incubated face down onto agar inoculated with the test microorganism. Inhibitory bands are visualized by staining the agar plates with tetrazolium red. The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen. The TLC methods apply to many types of plant extracts and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

  12. Microstructures and thermoelectric properties of GeSbTe based layered compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yan, F.; Zhu, T.J.; Zhao, X.B. [Zhejiang University, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Hangzhou (China); Dong, S.R. [Zhejiang University, Department of Information and Electronics Engineering, Hangzhou (China)

    2007-08-15

    Microstructures and thermoelectric properties of Ge{sub 1}Sb{sub 2}Te{sub 4} and Ge{sub 2}Sb{sub 2}Te{sub 5} chalcogenide semiconductors have been investigated to explore the possibility of their thermoelectric applications. The phase transformation from the face-centered cubic to hexagonal structure was observed in Ge{sub 2}Sb{sub 2}Te{sub 5} compounds prepared by the melt spinning technique. The Seebeck coefficient and electrical resistivity of the alloys were increased due to the enhanced scattering of charge carriers at grain boundaries. The maximum power factors of the rapidly solidified Ge{sub 1}Sb{sub 2}Te{sub 4} and Ge{sub 2}Sb{sub 2}Te{sub 5} attained 0.975 x 10{sup -3} Wm{sup -1}K{sup -2} at 750 K and 0.767 x 10{sup -3} Wm{sup -1}K{sup -2} at 643 K respectively, higher than those of water quenched counterparts, implying that thermoelectric properties of GeSbTe based layered compounds can be improved by grain refinement. The present results show this class of chalcogenide semiconductors is promising for thermoelectric applications. (orig.)

  13. Layered lithium cobalt nitrides: A new class of lithium intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ducros, J.B.; Bach, S.; Pereira-Ramos, J.P. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR CNRS 7182, 2 rue Henri-Dunant, 94320 Thiais (France); Willmann, P. [Centre National d' Etudes Spatiales, 118 avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2008-01-03

    Lithium cobalt nitrides Li{sub 3-2x}Co{sub x}N (0.1 {<=} x {<=} 0.44) have been prepared and investigated as negative electrode in the 1/0.02 V potential window. The evolution of the unit cell parameters and unit cell volume with the Co content show a solid solution behaviour. Whatever the Co content, all these nitrides are electroactive with a single step around 0.6 V/0.7 V for the discharge and charge processes, respectively. The electrochemical behaviour observed is typical of a Li intercalation compound and involves the Co{sup 2+}/Co{sup +} redox couple in the interlayer plane combined with the reversible accommodation of Li{sup +} ions in the cation vacancies located in Li{sub 2}N{sup -} layers. XRD experiments performed after discharge, charge and cycling tests clearly indicate the hexagonal layered structure of the host lattice is maintained. This intercalation process explains the excellent capacity retention found after 50 cycles. A specific capacity of 180 mAh g{sup -1} at C/20 and 130 mAh g{sup -1} at C/5 rate (100 mA cm{sup -2}) is achieved for Li{sub 2.23}Co{sub 0.39}N. ac impedance measurements have allowed to characterize the kinetics of the reaction. (author)

  14. GaSb on GaAs solar cells Grown using interfacial misfit arrays (Conference Presentation)

    Science.gov (United States)

    Nelson, George T.; Juang, Bor-Chau; Slocum, Michael A.; Bittner, Zachary S.; Laghumavarapu, Ramesh Babu B.; Huffaker, Diana L.; Hubbard, Seth M.

    2017-04-01

    State of the art InGaP2/GaAs/In0.28Ga0.72As inverted metamorphic (IMM) solar cells have achieved impressive results, however, the thick metamorphic buffer needed between the lattice matched GaAs and lattice mismatched InGaAs requires significant effort and time to grow and retains a fairly high defect density. One approach to this problem is to replace the bottom InGaAs junction with an Sb-based material such as 0.73 eV GaSb or 1.0 eV Al0.2Ga0.8Sb. By using interfacial misfit (IMF) arrays, the high degree of strain (7.8%) between GaAs and GaSb can be relaxed solely by laterally propagating 90° misfit dislocations that are confined to the GaAs-GaSb interface layer. We have used molecular beam epitaxy to grow GaSb single junction solar cells homoepitaxially on GaSb and heteroepitaxially on GaAs using IMF. Under 15-sun AM1.5 illumination, the control cell achieved 5% efficiency with a WOC of 366 mV, while the IMF cell was able to reach 2.1% with WOC of 546 mV. Shunting and high non-radiative dark current were main cause of FF and efficiency loss in the IMF devices. Threading dislocations or point defects were the expected source behind the losses, leading to minority carrier lifetimes less than 1ns. Deep level transient spectroscopy (DLTS) was used to search for defects electrically and two traps were found in IMF material that were not detected in the homoepitaxial GaSb device. One of these traps had a trap density of 7 × 1015 cm-3, about one order of magnitude higher than the control cell defect at 4 × 1016 cm-3.

  15. Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells

    National Research Council Canada - National Science Library

    Park, Keunhee; Oh, Seungsik; Jung, Donggeun; Chae, Heeyeop; Kim, Hyoungsub; Boo, Jin-Hyo

    2012-01-01

    ...) + [6, 6]-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively...

  16. Nanoscale Structuring by Misfit Dislocations in Si1-xGex/Si Epitaxial Systems

    DEFF Research Database (Denmark)

    Shiryaev, S.Y.; Jensen, Flemming; Hansen, J. Lundsgaard;

    1997-01-01

    New capabilities of misfit dislocations for spatial manipulation of islands in Si1-xGex/Si heteroepitaxial systems have been elucidated. Formation of highly ordered Ge-island patterns on substrates prestructured by slip bands of misfit dislocations is revealed. The major sources leading to the or...

  17. Full waveform modelling and misfit calculation using the VERCE platform

    Science.gov (United States)

    Garth, Thomas; Spinuso, Alessandro; Casarotti, Emanuele; Magnoni, Federica; Krischner, Lion; Igel, Heiner; Schwichtenberg, Horst; Frank, Anton; Vilotte, Jean-Pierre; Rietbrock, Andreas

    2016-04-01

    In recent years the increasing resolution of seismic imagining by full waveform inversion has opened new research perspectives and practices. These methods rely on harnessing the computational power of large supercomputers and new storage capabilities, to run large parallel codes to simulate the seismic wave field in three-dimensional geological settings. The VERCE platform is designed to make these full waveform techniques accessible to a far wider spectrum of the seismological community. VERCE empowers a broad base of seismology researchers to harvest the new opportunities provided by well-established high-performance wave simulation codes such as SPECFEM3D. It meets a range of seismic research needs by eliminating the technical difficulties associated with using these codes, allowing users to focus on their research questions. VERCE delivers this power to seismologists through its science gateway, supporting wave simulation codes on each of the provided computing resources. Users can design their waveform simulation scenarios making use of a library of pre-loaded meshes and velocity models, and services for selecting earthquake focal mechanisms, seismic stations and recorded waveforms from existing catalogues, such as the GCMT catalogue, and FDSN data sources. They can also supply their own mesh, velocity model, earthquake catalogue and seismic observations. They can submit the simulations onto different computing resources, where VERCE provides codes that are tuned and supported for those resources. The simulations can currently be run on a range of European supercomputers in the PRACE network, including superMUC at LRZ, GALILEO at CINECA and on selected resources like Drachenfels at SCAI and within the EGI network. The gateway automates and looks after all these stages, but supplies seismologists with a provenance system that allows them to manage a large series of runs, review progress, and explore the results. The platform automates misfit analysis between

  18. Magnetization states in epitaxial thin films subjected to misfit strains and demagnetization field

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Junqing [Department of Applied Mathematics, School of Science, Zhejiang University of Technology, Hangzhou, Zhejiang 310014 (China); Wang, Jie, E-mail: jw@zju.edu.cn [Institute of Applied Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2015-01-15

    The effect of non-equally biaxial in-plane misfit strains and demagnetization field on the magnetization states of ferromagnetic thin films is analytically investigated by using a nonlinear thermodynamic theory. The “misfit strain–misfit strain” phase diagrams of the magnetization states at room temperature for α-Fe and CoFe{sub 2}O{sub 4} thin films epitaxially grown on tetragonal substrates are developed by minimizing the total free energy. For a cubic ferromagnetic thin film, an out-of-plane magnetization state exists in the region of tensile misfit strains if the magnetostrictive coefficient of λ{sub 100} is negative and the demagnetization field is small, whereas the out-of-plane magnetization vanishes in the whole region of misfit strains when the demagnetization field is large.

  19. Tuning Slow Magnetic Relaxation in a Two-Dimensional Dysprosium Layer Compound through Guest Molecules.

    Science.gov (United States)

    Chen, Qi; Li, Jian; Meng, Yin-Shan; Sun, Hao-Ling; Zhang, Yi-Quan; Sun, Jun-Liang; Gao, Song

    2016-08-15

    A novel two-dimensional dysprosium(III) complex, [Dy(L)(CH3COO)]·0.5DMF·H2O·2CH3OH (1), has been successfully synthesized from a new pyridine-N-oxide (PNO)-containing ligand, namely, N'-(2-hydroxy-3-methoxybenzylidene)pyridine-N-oxidecarbohydrazide (H2L). Single-crystal X-ray diffraction studies reveal that complex 1 is composed of a dinuclear dysprosium subunit, which is further extended by the PNO part of the ligand to form a two-dimensional layer. Magnetic studies indicate that complex 1 shows well-defined temperature- and frequency-dependent signals under a zero direct-current (dc) field, typical of slow magnetic relaxation with an effective energy barrier Ueff of 33.6 K under a zero dc field. Interestingly, powder X-ray diffraction and thermogravimetric analysis reveal that compound 1 undergoes a reversible phase transition that is induced by the desorption and absorption of methanol and water molecules. Moreover, the desolvated sample [Dy(L)(CH3COO)]·0.5DMF (1a) also exhibits slow magnetic relaxation but with a higher anisotropic barrier of 42.0 K, indicating the tuning effect of solvent molecules on slow magnetic relaxation.

  20. Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer

    Science.gov (United States)

    Mungall, Emma L.; Abbatt, Jonathan P. D.; Wentzell, Jeremy J. B.; Lee, Alex K. Y.; Thomas, Jennie L.; Blais, Marjolaine; Gosselin, Michel; Miller, Lisa A.; Papakyriakou, Tim; Willis, Megan D.; Liggio, John

    2017-06-01

    Summertime Arctic shipboard observations of oxygenated volatile organic compounds (OVOCs) such as organic acids, key precursors of climatically active secondary organic aerosol (SOA), are consistent with a novel source of OVOCs to the marine boundary layer via chemistry at the sea surface microlayer. Although this source has been studied in a laboratory setting, organic acid emissions from the sea surface microlayer have not previously been observed in ambient marine environments. Correlations between measurements of OVOCs, including high levels of formic acid, in the atmosphere (measured by an online high-resolution time-of-flight mass spectrometer) and dissolved organic matter in the ocean point to a marine source for the measured OVOCs. That this source is photomediated is indicated by correlations between the diurnal cycles of the OVOC measurements and solar radiation. In contrast, the OVOCs do not correlate with levels of isoprene, monoterpenes, or dimethyl sulfide. Results from box model calculations are consistent with heterogeneous chemistry as the source of the measured OVOCs. As sea ice retreats and dissolved organic carbon inputs to the Arctic increase, the impact of this source on the summer Arctic atmosphere is likely to increase. Globally, this source should be assessed in other marine environments to quantify its impact on OVOC and SOA burdens in the atmosphere, and ultimately on climate.

  1. Education, mental health, and education-labor market misfit.

    Science.gov (United States)

    Bracke, Piet; van de Straat, Vera; Missinne, Sarah

    2014-12-01

    Higher-educated people experience enhanced mental health. We ponder whether the mental health benefits of educational attainment are limitless. At the individual level, we look at the impact of job-education mismatch. At the societal level, we hypothesize that diminishing economic returns on education limit its mental health benefits. Using a subsample of individuals aged 20 to 65 years (N = 28,288) from 21 countries in the European Social Survey (ESS 2006), we estimate the impact on depressive symptoms of characteristics at both the employee level (years of education and job-education mismatch) and the labor market/country level (the gap between the nontertiary and tertiary educated in terms of unemployment risks and earnings). The results show that educational attainment produces mental health benefits in most European countries. However, in some of the countries, these benefits are limited or even completely eliminated by education-labor market misfit. © American Sociological Association 2014.

  2. Surface and boundary layer exchanges of volatile organic compounds, nitrogen oxides and ozone during the GABRIEL campaign

    NARCIS (Netherlands)

    Ganzeveld, L.; Eerdekens, G.; Feig, G.; Fischer, H.; Harder, H.; Konigstedt, R.; Kubistin, D.; Martinez, M.; Meixner, F. X.; Scheeren, H. A.; Sinha, V.; Taraborrelli, D.; Williams, J.; de Arellano, J. Vila-Guerau; Lelieveld, J.

    2008-01-01

    We present an evaluation of sources, sinks and turbulent transport of nitrogen oxides, ozone and volatile organic compounds (VOC) in the boundary layer over French Guyana and Suriname during the October 2005 GABRIEL campaign by simulating observations with a single-column chemistry and climate model

  3. Full-waveform inversion of triplicated data using a normalized-correlation-coefficient-based misfit function

    Science.gov (United States)

    Tao, Kai; Grand, Stephen P.; Niu, Fenglin

    2017-09-01

    In seismic full-waveform inversion (FWI), the choice of misfit function determines what information in data is used and ultimately affects the resolution of the inverted images of the Earth's structure. Misfit functions based on traveltime have been successfully applied in global and regional tomographic studies. However, wave propagation through the upper mantle results in multiple phases arriving at a given receiver in a narrow time interval resulting in complicated waveforms that evolve with distance. To extract waveform information as well as traveltime, we use a misfit function based on the normalized correlation coefficient (CC). This misfit function is able to capture the waveform complexities in both phase and relative amplitude within the measurement window. It is also insensitive to absolute amplitude differences between modeled and recorded data, which avoids problems due to uncertainties in source magnitude, radiation pattern, receiver site effects or even miscalibrated instruments. These features make the misfit function based on normalized CC a good candidate to achieve high-resolution images of complex geological structures when interfering phases coexist in the measurement window, such as triplication waveforms. From synthetic tests, we show the advantages of this misfit function over the cross-correlation traveltime misfit function. Preliminary inversion of data from an earthquake in Northeast China images a sharper and stronger amplitude slab stagnant in the middle of the transition zone than FWI of cross-correlation traveltime.

  4. Ab-initio investigation of the influence of chemical compounds on graphene layer properties in fabricated IR detector

    Science.gov (United States)

    Ruta, L.; Wozny, J.; Szczecinska, N.; Lisik, Z.

    2016-11-01

    In this work, the influence of H2O, NaOH and propanol on properties of graphene layer placed on SiO2 has been investigated. These chemical particles are present during technological steps required for a device fabrication and may lead to significant changes of graphene properties. The investigation has been done by means of ab-initio simulation based on the DFT method. A MedeA-VASP package was used to investigate behavior of graphene layer in the vicinity of chemical compounds. Presented studies show that properties of graphene are significantly modified when particles of H2O and NaOH are captured in-between graphene layer and SiO2. Special attention should be paid to NaOH which, according to simulations, decays and modifies the properties of graphene layer.

  5. Ion-assisted MBE for misfit-dislocation templates serving ordered growth of SiGe islands

    Energy Technology Data Exchange (ETDEWEB)

    Lyutovich, K. [Universitaet Stuttgart, Institut fuer Halbleitertechnik, Pfaffenwaldring 47, D-70569 Stuttgart (Germany)], E-mail: lyutovich@iht.uni-stuttgart.de; Oehme, M.; Werner, J.; Bahouchi, B.; Kasper, E. [Universitaet Stuttgart, Institut fuer Halbleitertechnik, Pfaffenwaldring 47, D-70569 Stuttgart (Germany); Hofer, C.; Teichert, C. [Institute of Physics, Montanuniversitaet Leoben, Franz Josef Str. 18, A-8700 Leoben (Austria)

    2008-11-03

    In this work, Si{sup +} ions generated by the electron-beam evaporator are employed to influence strain and morphology of MBE-grown SiGe layers on Si (100) substrates. Strain relaxation of SiGe layers and modified surface morphology are attained by ion bombardment at reduced growth temperature. A study on the influence of ion energy (0-1000 eV) and density on both degree of relaxation and surface morphology is performed. Regular misfit-dislocation networks and a specific surface morphology are observed when the in situ ion bombardment at reduced temperatures leads to a degree of relaxation around 25%. This surface morphology shows uniform shallow pyramids ordered in <110> directions which provide a template favourable for nanomagnets and other opto- and nanoelectronic applications.

  6. Formation of periodic interfacial misfit dislocation array at the InSb/GaAs interface via surface anion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Bo Wen; Tan, Kian Hua; Loke, Wan Khai; Wicaksono, Satrio; Yoon, Soon Fatt [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2016-07-21

    The relationship between growth temperature and the formation of periodic interfacial misfit (IMF) dislocations via the anion exchange process in InSb/GaAs heteroepitaxy was systematically investigated. The microstructural and electrical properties of the epitaxial layer were characterized using atomic force microscope, high-resolution x-ray diffraction, transmission electron microscopy, and Hall resistance measurement. The formation of interfacial misfit (IMF) dislocation arrays depended on growth temperature. A uniformly distributed IMF array was found in a sample grown at 310 °C, which also exhibited the lowest threading dislocation density. The analysis suggested that an incomplete As-for-Sb anion exchange process impeded the formation of IMF on sample grown above 310 °C. At growth temperature below 310 °C, island coalescence led to the formation of 60° dislocations and the disruption of periodic IMF array. All samples showed higher electron mobility at 300 K than at 77 K.

  7. Characterization of {gamma}{prime}-Fe{sub 4}N precipitates in a compound layer formed by austenitic nitrocarburizing treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Rong, Y.; Chen, X.; Hu, G. [Shanghai Jiao Tong Univ., Shanghai (China). Dept. of Materials Science

    1995-04-01

    The precipitation of {gamma}{prime}-Fe{sub 4}N phase from the {var_epsilon}-matrix in a quenched and aged compound layer of 0.2% C steel formed by austenitic nitrocarburizing treatment has been investigated through transmission electron microscopy. The orientation relationships between the {gamma}{prime} phase and the {var_epsilon} matrix is determined to be {l_brace}0001{r_brace}{sub {var_epsilon}}//{l_brace}111{r_brace}{sub {gamma}{prime}} and <1{bar 2}10>{sub {var_epsilon}}//<011>{sub {gamma}{prime}}. The {gamma}{prime} precipitates appearing in thin plates in the {l_brace}0001{r_brace} planes of {var_epsilon} matrix are sometimes observed to be 180{degree} related to each other. The mechanism of age-hardening in the compound layer is also discussed.

  8. Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy.

    Science.gov (United States)

    Jeong, Jaewoo; Ferrante, Yari; Faleev, Sergey V; Samant, Mahesh G; Felser, Claudia; Parkin, Stuart S P

    2016-01-18

    Although high-tunnelling spin polarization has been observed in soft, ferromagnetic, and predicted for hard, ferrimagnetic Heusler materials, there has been no experimental observation to date of high-tunnelling magnetoresistance in the latter. Here we report the preparation of highly textured, polycrystalline Mn3Ge films on amorphous substrates, with very high magnetic anisotropy fields exceeding 7 T, making them technologically relevant. However, the small and negative tunnelling magnetoresistance that we find is attributed to predominant tunnelling from the lower moment Mn-Ge termination layers that are oppositely magnetized to the higher moment Mn-Mn layers. The net spin polarization of the current reflects the different proportions of the two distinct termination layers and their associated tunnelling matrix elements that result from inevitable atomic scale roughness. We show that by engineering the spin polarization of the two termination layers to be of the same sign, even though these layers are oppositely magnetized, high-tunnelling magnetoresistance is possible.

  9. Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy

    Science.gov (United States)

    Jeong, Jaewoo; Ferrante, Yari; Faleev, Sergey V.; Samant, Mahesh G.; Felser, Claudia; Parkin, Stuart S. P.

    2016-01-01

    Although high-tunnelling spin polarization has been observed in soft, ferromagnetic, and predicted for hard, ferrimagnetic Heusler materials, there has been no experimental observation to date of high-tunnelling magnetoresistance in the latter. Here we report the preparation of highly textured, polycrystalline Mn3Ge films on amorphous substrates, with very high magnetic anisotropy fields exceeding 7 T, making them technologically relevant. However, the small and negative tunnelling magnetoresistance that we find is attributed to predominant tunnelling from the lower moment Mn-Ge termination layers that are oppositely magnetized to the higher moment Mn-Mn layers. The net spin polarization of the current reflects the different proportions of the two distinct termination layers and their associated tunnelling matrix elements that result from inevitable atomic scale roughness. We show that by engineering the spin polarization of the two termination layers to be of the same sign, even though these layers are oppositely magnetized, high-tunnelling magnetoresistance is possible.

  10. One-atom-layer 4×4 compound in (Tl, Pb)/Si(111) system

    Science.gov (United States)

    Mihalyuk, A. N.; Hsing, C. R.; Wei, C. M.; Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Zotov, A. V.; Saranin, A. A.

    2017-03-01

    An ordered 4×4-periodicity 2D compound has been found in the (Tl, Pb)/Si(111) system and its composition, structure and electronic properties have been characterized using low-energy electron diffraction, scanning tunneling microscopy observations and density-functional-theory calculations. The compound has been concluded to contain 9 Tl atoms and 12 Pb atoms per 4×4 unit cell, i.e., 0.56 ML of Tl and 0.75 ML of Pb. Structural model was proposed for the 4×4-(Tl, Pb) compound where building blocks are a hexagonal array of 12 Pb atoms, a triangular array of 6 Tl atoms and a Tl trimer. The proposed structure has a C3 symmetry and occurs in the two equivalent orientations. The electron band structure of the compound contains two metallic spin-split surface-state bands. Bearing in mind the advanced properties of the known √{ 3 } ×√{ 3 } 2D compound in the same (Tl, Pb)/Si(111) system (i.e., combination of giant Rashba effect and superconductivity), the found 4×4-(Tl, Pb) compound is believed to be a promising object for exploration of its superconductive properties.

  11. Band gap engineering of tandem structured CIGS compound absorption layer fabricated by sputtering and selenization

    Energy Technology Data Exchange (ETDEWEB)

    Kang, San; Sharma, Rahul; Sim, Jae-Kwan [Semiconductor Materials Processing Laboratory, School of Advanced Materials Engineering, College of Engineering, Research Center for Advanced Materials Development (RCAMD), Chonbuk National University, Deokjin-dong 664-14, Jeonju 561-756 (Korea, Republic of); Lee, Cheul-Ro, E-mail: crlee7@jbnu.ac.kr [Semiconductor Materials Processing Laboratory, School of Advanced Materials Engineering, College of Engineering, Research Center for Advanced Materials Development (RCAMD), Chonbuk National University, Deokjin-dong 664-14, Jeonju 561-756 (Korea, Republic of)

    2013-06-25

    Highlights: ► Systematic band gap engineering to fabricate tandem Cu(In,Ga)Se{sub 2} absorption layers. ► XRD shows prominent (1 1 2) reflection shift for attributed CIS, CIGS, and CGS phases. ► Optical transmittance and reflectance spectrum are improved towards infrared region. ► The Cu/In + Ga and Ga/In + Ga effect is matched with highest efficient solar cell. ► Tandem CIS/CIGS/CGS layer, the band gap is increased from 1.15 to 2.06 eV. -- Abstract: Band gap engineering was executed to fabricate a multi-junction stacked i.e. tandem Cu(In,Ga)Se{sub 2} (CIGS) absorption layer. The CIGS absorption layers consist of multi-junction stacked CIS/CIGS/CGS thin films from bottom to top with increasing band gap. Tandem CIGS layers were fabricated by using three precursor of CuIn, In/CuGa/In, and CuGa onto the Mo coated soda-lime glass (SLG) by the sequential sputtering of CuIn, CuGa, and In targets. The CIG precursors were converted into CIGS absorption thin film by selenization process. From the X-ray diffraction (XRD) pattern of CIS/CIGS/CGS tandem layer, with the prominent peak shift for (1 1 2) reflections was attributed to the individual CIS, CIGS, and CGS phases at 26.76°, 27.15°, and 27.65° diffraction angles, respectively. The morphologies and atomic (at%) composition uniformity onto the surface and along the depth were extensively analyzed with field effect scanning electron microscope (FESEM) attached energy dispersive spectroscopy (EDS) and secondary ion mass spectroscopy (SIMS). The optical properties such as transmittance, reflectance and absorbance were found to improve in the infrared region for all the tandem CIGS layers. Near the fundamental absorption edge, the absorption coefficient was approached to 10{sup 5} cm{sup −1} for CIS/CIGS/CGS tandem layer. The straight-line behavior indicates that the films have a direct band gap. The band gap was found to increase from 1.15 to 1.74 eV with the Ga-grading along the depth of individual CIS, CIGS

  12. Effect of non-strained capping layer on excess stress in strained layers

    Institute of Scientific and Technical Information of China (English)

    金智; 杨树人; 马春生; 安海岩; 王本忠; 刘式墉

    1999-01-01

    The effects of the capping-layer thickness and the discrepancy of the numbers of misfit dislocations at the upper and lower interfaces in capped layer on the excess stress are considered. Based on this, the formulae of excess stresses for single- and double-kink models are modified and a new formula is derived, which unifies single- and doublekink models and is valid for arbitrary capping-layer thickness. It is useful to complete the description of the formation and motion of misfit dislocations in strained layers.

  13. Identification of triterpenoid compounds of Centella asiatica by thin-layer chromatography and mass spectrometry.

    Science.gov (United States)

    Bonfill, Mercè; Mangas, Susana; Cusidó, Rosa M; Osuna, Lidia; Piñol, M Teresa; Palazón, Javier

    2006-02-01

    The identification of the four principal triterpenoid components of Centella asiatica has been achieved by TLC on silica gel plates and mass spectrometry, as a modification of the method described in the European Pharmacopoeia (5th edn). A combination of ethyl acetate and methanol as the mobile phase was found to be successful in separating these compounds from the rest of the main components of the extract. The spots were detected with anisaldehyde solution. The separated compounds were confirmed by MALDI -TOF mass spectrometry.

  14. The Role of Lattice Misfit on Heterogeneous Nucleation of Pure Aluminum

    Science.gov (United States)

    Wang, L.; Yang, L.; Zhang, D.; Xia, M.; Wang, Y.; Li, J. G.

    2016-10-01

    α-Alumina (Al2O3) single crystals with different termination planes were used as heterogeneous nucleation substrates for liquid aluminum to varying lattice misfits at the interface between substrate and newly nucleated aluminum grain. Undercooling during the nucleation process was measured for interface configurations with varied lattice misfit, while the solidified Al/Al2O3 interfaces were directly observed by high-resolution transmission electron microscopy (HRTEM). Based on experimental results, the effect of lattice misfit on nucleation behavior was systematically investigated following previous misfit-interfacial energy models, with clarification being made by the undercooling measurement and HRTEM observations of the interfaces in the Al/Al2O3 system. When the misfit is smaller than 13 pct, both experimental results and theoretical analysis show that the currently existing models through modification and incorporating energy calculation can be used to fit the detected undercooling of investigated system. Beyond 13 pct, a new hypothesis was developed to accommodate lattice misfit with stacking faults such as microtwins according to the HRTEM analysis. The interfacial energy is then replaced by the stacking fault energy accumulated in the strained area. It is shown that the lattice misfit plays an important role in determining the heterogeneous nucleation of liquid aluminum. The nucleation undercooling is then able to be predicted by the theoretically calculated interfacial energy using the integrated models developed in the work. The prediction results were also verified by the HRTEM analysis on the nucleation interface of the Al/Al2O3 systems and detected undercooling on corresponding systems.

  15. Density functional theory investigation of the electronic structure and thermoelectric properties of layered MoS{sub 2}, MoSe{sub 2} and their mixed-layer compound

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Changhoon; Hong, Jisook [Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Lee, Wang Ro [Faculty of Liberal Education, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Dae Yeon [Agency for Defense Development (ADD), Chinhae, Kyungnam 645-600 (Korea, Republic of); Shim, Ji Hoon, E-mail: jhshim@postech.ac.kr [Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Divisions of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-15

    First principles density functional theory calculations were carried out for the 2H-MoQ{sub 2} (Q=S and Se) and their hypothetical mixed-layer compound. Due to the different electronegativities of S and Se atoms on MoQ{sub 2}, the band gap size could be adjusted in mixed-layer compound MoS{sub 2}/MoSe{sub 2}. Also, the indirect band gap in pure MoQ{sub 2} compounds is changed to the pseudo direct band gap in mixed-layer MoS{sub 2}/MoSe{sub 2} which is similar to the monolayer compound. The layer mixing enhances the thermoelectric properties because of the increased density of states around the Fermi level and the decreased band gap size. Therefore, we suggest that this layer mixing approach should be regarded as a useful way to modulate their electronic structures and to improve their thermoelectric properties. -- Graphical abstract: On the basis of density functional calculations we predict that the mixed-layer compounds 2H-MoS{sub 2}/2H-MoSe{sub 2}, in which two different layers 2H-MoS{sub 2} and 2H-MoSe{sub 2}, have enhanced thermoelectric properties because of the increased density of states around the Fermi level and the decreased band gap size. Highlights: • We explored a way of improving TE properties of 2H-MoQ{sub 2} on DFT methods. • The mixed-layer compounds MoS{sub 2}/MoSe{sub 2} have enhanced thermoelectric properties. • This is caused by modulated electronic structure of mixed layer compound. • Layer mixing approach should be regarded as a useful way to improve TE properties.

  16. Synthesis and Characterization of a New Triple-layered Perovskite KSr2Nb3O10 and Its Protonated Compounds

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2Nb3O10*1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction.These new compounds were characterized by EPMA,AAS,XRD,IR,DTA and so on.The structure may be described as treble perovskite sheets [Sr2Nb3O10]- interleaved with K+,H3O+ or H+.These new compounds are new members of the Dion-Jacobsonseries with n=3 for the general formula M[An-1NbnO3n+1],and their indexed X-ray powder diffraction data were first reported in the paper.

  17. Detection of Phenolic and Flavonoid Compounds Using High Performance Thin Layer Chromatography (HPTLC).

    Science.gov (United States)

    2016-01-01

    High performance thin layer chromatography (HPTLC) is a sophisticated instrumental technique based on the full capabilities of thin layerchromatography. The advantages of automation, scanning, full optimization, selective detection principle, minimum sample preparation,hyphenation, etc., enable it to be a powerful analytical tool for chromatographic information of complex mixtures of inorganic, organic andbiomolecules which are characterized in this chapter.

  18. Tracking of buried layers during plasma-assisted femtosecond laser drilling of compound targets

    Energy Technology Data Exchange (ETDEWEB)

    Zhvaniya, I. A., E-mail: irina.zhvaniya@physics.msu.ru; Garmatina, A. A.; Makarov, I. A.; Gordienko, V. M. [Faculty of Physics and International Laser Center, M.V. Lomonosov Moscow State University, 119991, GSP-1, 1-2 Leninskiye Gory, Moscow (Russian Federation)

    2016-07-28

    It was shown that drilling of multi-layered target placed in the air by tightly focused femtosecond laser radiation with high fluence (up to 1000 J/cm{sup 2}) can be monitored online using plasma-induced X-ray emission and second harmonic of incident laser radiation. The technique based on X-rays registration is appeared to be more flexible than the method based on detection of second harmonic since its accuracy depends crucially on the target type. We demonstrated that the X-ray signal clearly indicates the transition from one layer to another during the microdrilling of targets consisting of 2–4 layers of titanium foil when a laser beam is focused beneath the target surface at a depth comparable to the layer thickness. The diagnostics of microchannel production in the chicken eggshell was performed for the first time. It was found that the presence of albumen beneath the shell accounts for longtime generation of X-ray pulses.

  19. The Evolution of Microstructure and Magnetic Properties of the Bismuth Layer Compounds with Cobalt Ions Substitution.

    Science.gov (United States)

    Wang, Weipeng; Shen, Xi; Wang, Wei; Guan, Xiangxiang; Yao, Yuan; Wang, Yanguo; Yu, Richeng

    2017-03-20

    One of the core issues for the A/B site doping in the bismuth layer magnetoelectric materials is to find out the evolution of the magnetic structure, crystal structure and elemental distribution, and the coupling effects between spin and lattice with the increase of ion substitution. Here, we have conducted systematic structural and physical property studies on the series samples of Bi5Ti3Fe1-xCoxO15. This work presents that Bi5Ti3Fe1-xCoxO15 forms a single four layer perovskite-like structure for 0 ≤ x < 0.67, while a three layer perovskite-like structure block begins to arise for x ≥ 0.67. With different cobalt content, the sample demonstrates antiferromagnetism, spin state determined magnetism, or magnetic anisotropy determined magnetism. The weak ferromagnetism is considered to be induced by the larger displacement of Co(3+) ions from the center of octahedra and the change of the spin state of Co(3+) ions. It is also observed that Fe and Co elements are homogeneously substituted in the three layer structure block, accompanied by the rotation (and/or distortion) of BO6 octahedra.

  20. Tracking of buried layers during plasma-assisted femtosecond laser drilling of compound targets

    Science.gov (United States)

    Zhvaniya, I. A.; Garmatina, A. A.; Makarov, I. A.; Gordienko, V. M.

    2016-07-01

    It was shown that drilling of multi-layered target placed in the air by tightly focused femtosecond laser radiation with high fluence (up to 1000 J/cm2) can be monitored online using plasma-induced X-ray emission and second harmonic of incident laser radiation. The technique based on X-rays registration is appeared to be more flexible than the method based on detection of second harmonic since its accuracy depends crucially on the target type. We demonstrated that the X-ray signal clearly indicates the transition from one layer to another during the microdrilling of targets consisting of 2-4 layers of titanium foil when a laser beam is focused beneath the target surface at a depth comparable to the layer thickness. The diagnostics of microchannel production in the chicken eggshell was performed for the first time. It was found that the presence of albumen beneath the shell accounts for longtime generation of X-ray pulses.

  1. Identification of reaction compounds in micrometric layers from gothic paintings using combined SR-XRD and SR-FTIR.

    Science.gov (United States)

    Salvadó, Nati; Butí, Salvador; Nicholson, James; Emerich, Hermann; Labrador, Ana; Pradell, Trinitat

    2009-07-15

    Synchrotron radiation X-ray diffraction (micro-SR-XRD) and Fourier transform infrared spectroscopy (micro-SR-FTIR) are used in the non-destructive identification of reaction and aging compounds from micrometric ancient painting layers. The combination of the micrometer size and non-destructive nature of the techniques together with the high resolution and brilliance of the synchrotron radiation has proved to be a procedure most advantageous for the study of reaction, aging and degradation processes. Copper, lead and calcium carboxylates and oxalates are determined in the chromatic, preparation and alteration layers from 15th century egg tempera and oil paintings. Their nature and crystallinity have been assessed. Some hypothesis about the mechanisms of development of both carboxylates and oxalates are presented.

  2. Electronic structure of the layer compounds GaSe and InSe in a tight-binding approach

    Science.gov (United States)

    Camara, M. O.; Mauger, A.; Devos, I.

    2002-03-01

    The three-dimensional band structure of the III-VI layer compounds GaSe and InSe has been investigated in the tight-binding approach. The pseudo-Hamiltonian matrix elements in the sp3s* basis are fit in order to reproduce the nonlocal pseudopotential band structure, in the framework of constrained optimization techniques using the conjugate gradient method. The results are in good agreement with the optical and photoemission experimental data. The scaling laws appropriate to the covalent bonding are violated by a fraction of eV only, which suggests that the interlayer interactions are not solely of the van der Waals type.

  3. Composition and misfit strain dependence of electrocaloric effect of Pb1-xSrxTiO3 thin films

    Institute of Scientific and Technical Information of China (English)

    Qiu Jian-Hua; Ding Jian-Ning; Yuan Ning-Yi; Wang Xiu-Qin

    2013-01-01

    A Landau-Devonshire thermodynamic theory is employed to investigate the effects of composition and misfit strain on the room-temperature electrocaloric effect of epitaxial Pb1-xSrxTiO3 thin films.The “temperature-misfit strain” phase diagrams with the Sr composition x of 0.1,0.3,and 0.5 are constructed.The introduction of Sr composition reduces the Curie temperature greatly,and enhances the electrocaloric effect.Moreover,the electrocaloric effect largely depends on the misfit strain.Therefore,the Sr composition and the misfit strain can be controlled to obtain the giant room-temperature electrocaloric effect.

  4. PVC用水滑石类热稳定剂的研究开发进展%Research Progress of PVC Hydrotalcites Layered Compounds Heat Stabilizer

    Institute of Scientific and Technical Information of China (English)

    崔小明

    2012-01-01

    The production methods, reaction mechanism and application progress of PVC hydrotalcites layered compounds (LDHs) heat stabilizer are introduced . The development direction of hydrotalcites layered compounds are pointed out.%介绍了PVC用水滑石类化合物(LDHs)热稳定剂的制备方法、作用机理以及应用进展,指出了其今后的发展方向.

  5. Effect of Vertical Misfit on Screw Joint Stability of Implant-Supported Crowns

    Science.gov (United States)

    Assunção, Wirley Gonçalves; Delben, Juliana Aparecida; Tabata, Lucas Fernando; Barão, Valentim Adelino Ricardo; Gomes, Érica Alves

    2011-08-01

    The passive fit between prosthesis and implant is a relevant factor for screw joint stability and treatment success. The aim of this study was to evaluate the influence of vertical misfit in abutment-implant interface on preload maintenance of retention screw of implant-supported crowns. The crowns were fabricated with different abutments and veneering materials and divided into 5 groups ( n = 12): Gold UCLA abutments cast in gold alloy veneered with ceramic (Group I) and resin (Group II), UCLA abutments cast in titanium veneered with ceramic (Group III) and resin (Group IV), and zirconia abutments with ceramic veneering (Group V). The crowns were attached to implants by gold retention screws with 35-N cm insertion torque. Specimens were submitted to mechanical cycling up to 106 cycles. Measurements of detorque and vertical misfit in abutment-implant interface were performed before and after mechanical cycling. ANOVA revealed statistically significant difference ( P 0.05) between vertical misfit and detorque value. It was concluded that vertical misfit did not influence torque maintenance and the abutments cast in titanium exhibited the highest misfit values.

  6. Effect of vertical misfit and clip material on stress distribution of overdentures under masticatory loading.

    Science.gov (United States)

    Dos Santos, Mateus Bertolini Fernandes; Zen, Bruno Massucato; Bacchi, Atais

    2016-10-01

    Framework misfit is a common problem observed in overdentures, which might result in prosthetic and biological complications. The aim of this study was to evaluate the influence of vertical misfit and clip material on the stress distribution in an overdenture-retaining bar system under masticatory loading. A 3-D finite element model of a resorbed jaw was created, including two implants and a bar-clip retained overdenture. A pressure of 100 MPa was applied to the right mandibular first molar. Different vertical misfit levels (50, 100, and 200 µm) and clip materials (plastic or gold) were evaluated. Data were evaluated using von Mises stress and microstrain. Vertical misfit amplification caused an increase in the microstrain values in the peri-implant bone tissue next to the ill-fitted component and increased the stresses in the prosthetic screws. The clip material influenced the stress and microstrain distribution in the prosthetic components and bone tissue. The levels of vertical misfit seem to be closely linked with the stress values in the prosthetic screws, mainly to that of the ill-fitted component. The gold clip presented an increase in the stress compared to the plastic clip.

  7. Improved misfit function for attenuation and speed reconstruction in ultrasound computed tomography

    Science.gov (United States)

    Pérez-Liva, M.; Udías, J. M.; Herraiz, J. L.

    2017-03-01

    The reconstruction of acoustic attenuation maps for transmission Ultrasound Computed Tomography (USCT) based on the standard least-squares full wave inversion method requires the accurate knowledge of the sound speed map in the region under study. Any deviation in the reconstructed speed maps creates a very significant bias in the attenuation map, as the standard least-squares misfit function is more sensitive to time misalignments than to amplitude differences of the signals. In this work, we propose a generalized misfit function which includes an additional term that accounts for the amplitude differences between the measured and the estimated signals. The functional gradients used to minimize the proposed misfit function were obtained using an adjoint field formulation and the fractional Laplacian wave equation. The forward and backward wave propagation was obtained with the parallelized GPU version of the software k-Wave and the optimization was performed with a line search method. A numerical phantom simulating breast tissue and synthetic noisy data were used to test the performance of the proposed misfit function. The attenuation was reconstructed based on a converged speed map. An edge-preserving regularization method based on total variation was also implemented. To quantify the quality of the results, the mean values and their standard deviations in several regions of interest were analyzed and compared to the reference values. The proposed generalized misfit function decreases considerably the bias in the attenuation map caused by the deviations in the speed map in all the regions of interest analyzed.

  8. Giant magneto-optical Raman effect in a layered transition metal compound.

    Science.gov (United States)

    Ji, Jianting; Zhang, Anmin; Fan, Jiahe; Li, Yuesheng; Wang, Xiaoqun; Zhang, Jiandi; Plummer, E W; Zhang, Qingming

    2016-03-01

    We report a dramatic change in the intensity of a Raman mode with applied magnetic field, displaying a gigantic magneto-optical effect. Using the nonmagnetic layered material MoS2 as a prototype system, we demonstrate that the application of a magnetic field perpendicular to the layers produces a dramatic change in intensity for the out-of-plane vibrations of S atoms, but no change for the in-plane breathing mode. The distinct intensity variation between these two modes results from the effect of field-induced broken symmetry on Raman scattering cross-section. A quantitative analysis on the field-dependent integrated Raman intensity provides a unique method to precisely determine optical mobility. Our analysis is symmetry-based and material-independent, and thus the observations should be general and inspire a new branch of inelastic light scattering and magneto-optical applications.

  9. Intercalation-induced phases in layer compounds of the A /SUP III/ B /SUP VI/ -type

    Energy Technology Data Exchange (ETDEWEB)

    Kovalyuk, Z.D.; Pyrlya, M.N.; Seredyuk, A.I.; Tovstyuk, K.D.

    1986-03-01

    The authors investigate the kinetics of combined electrochemical intercalation and the physicochemical properties of the introduced phases. InSe and GaSe single crystals were used in the experiments; the crystals were grown by the Bridgman method. The authors determined the concentration dependences of the electrode potentials and electrical conductivity of the compounds InSe and GaSe intercalated with lithium and lead. The results of the measurements are presented. Lithium and lead enter into the matrix of the crystals in a nonconducting state.

  10. Magnetic properties of the new rare earth carbide fluoride layered compound: Ho 2CF 2

    Science.gov (United States)

    Kremer, R. K.; Cockcroft, J. K.; Mattausch, Hj.; Raju, N. P.; Simon, A.

    1992-02-01

    We present magnetic susceptibility, specific heat and neutron diffraction data of the new layered rare earth carbide flouride Ho 2CF 2. The susceptibility displays a rounded maximum centered around 4.6 K and a Curie-Weiss law at higher temperatures with a paramagnetic Curie temperature of -4.9(2) K. The specific heat shows a sharp anomaly at 3.61(5) K indicating the onset of long range ordering but also a considerable high temperature tail pointing to low dimensional magnetic behaviour. Low temperature neutron powder diffraction reveals additional magnetic Bragg peaks with significant critical scattering remaining well above the long range ordering temperature.

  11. Excitonic optical nonlinearities and transport in the layered compound semiconductor GaSe

    DEFF Research Database (Denmark)

    Mizeikis, V.; Vadim, Lyssenko; Østergaard, John Erland;

    1995-01-01

    Dephasing and transient grating experiments in the direct excitonic absorption region of GaSe at low temperatures show that a fast relaxation within the one-dimensionally disordered excitonic band results in band filling being the dominant mechanism of the optical nonlinearity. Correspondingly, we...... observe a blueshift of the nonlinear signal with excitation density. The temperature dependence of the exciton diffusion constant measured in directions parallel to the GaSe layer planes indicates that temperature-independent scattering (trapping) and scattering by acoustic phonons determine the exciton...

  12. How fit turns into misfit and back: Institutional Transformations of Pastoral Commons in African Floodplains

    Directory of Open Access Journals (Sweden)

    Tobias Haller

    2013-03-01

    Full Text Available We enlarge the notion of institutional fit using theoretical approaches from New Institutionalism, including rational choice and strategic action, political ecology and constructivist approaches. These approaches are combined with ecological approaches (system and evolutionary ecology focusing on feedback loops and change. We offer results drawn from a comparison of fit and misfit cases of institutional change in pastoral commons in four African floodplain contexts (Zambia, Cameroon, Tanzania (two cases. Cases of precolonial fit and misfit in the postcolonial past, as well as a case of institutional fit in the postcolonial phase, highlight important features, specifically, flexible institutions, leadership, and mutual economic benefit under specific relations of bargaining power of actors. We argue that only by combining otherwise conflicting approaches can we come to understand why institutional fit develops into misfit and back again.

  13. Misfit dislocations and phase transformations in high-T sub c superconducting films

    CERN Document Server

    Gutkin, M Y

    2002-01-01

    A theoretical model is suggested that describes the effects of misfit stresses on defect structures, phase content and critical transition temperature T sub c in high-T sub c superconducting films. The focus is placed on the exemplary case of YBaCuO films deposited onto LaSrAlO sub 4 substrates. It is theoretically revealed here that misfit stresses are capable of inducing phase transformations controlled by the generation of misfit dislocations in growing cuprate films. These transformations, in the framework of the suggested model, account for experimental data on the influence of the film thickness on phase content and critical temperature T sub c of superconducting cuprate films, reported in the literature. The potential role of stress-assisted phase transformations in suppression of critical current density across grain boundaries in high-T sub c superconductors is briefly discussed.

  14. Flowing atmospheric pressure afterglow combined with laser ablation for direct analysis of compounds separated by thin-layer chromatography.

    Science.gov (United States)

    Cegłowski, Michał; Smoluch, Marek; Reszke, Edward; Silberring, Jerzy; Schroeder, Grzegorz

    2016-01-01

    A thin-layer chromatography-mass spectrometry (TLC-MS) setup for characterization of low molecular weight compounds separated on standard TLC plates has been constructed. This new approach successfully combines TLC separation, laser ablation, and ionization using flowing atmospheric pressure afterglow (FAPA) source. For the laser ablation, a low-priced 445-nm continuous-wave diode laser pointer, with a power of 1 W, was used. The combination of the simple, low-budget laser pointer and the FAPA ion source has made this experimental arrangement broadly available, also for small laboratories. The approach was successfully applied for the characterization of low molecular weight compounds separated on TLC plates, such as a mixture of pyrazole derivatives, alkaloids (nicotine and sparteine), and an extract from a drug tablet consisting of paracetamol, propyphenazone, and caffeine. The laser pointer used was capable of ablating organic compounds without the need of application of any additional substances (matrices, staining, etc.) on the TLC spots. The detection limit of the proposed method was estimated to be 35 ng/cm(2) of a pyrazole derivative.

  15. Utilization of Eco-Feed Containing Mugwort Microorganism Compounds as a Feed Ingredient Source for Layer Hens

    Directory of Open Access Journals (Sweden)

    J. Ruttanavut

    2011-01-01

    Full Text Available Problem statement: Due to price hikes in feed, several strategies should be sought to reduce feeding costs. At the same time, there has been a considerable increase in environmental pollution from food waste. If food waste could be transferred into poultry diets, this would solve a great problem, helping poultry producers to reduce feeding costs, while reducing environmental problems arising from the disposal of food waste. The present study was performed to evaluate the possibility that Eco-feed (feed produced from recycled food waste can be used as a feed ingredient source for layer hens. Approach: To promote the quality of conventional Eco-feed, it was sunk into Japanese Mugwort Silage Juice (JMSJ including microorganism compounds and combined with a compound of microorganisms derived from JMSJ, resulting in Eco-feed Containing Mugwort microorganism compounds (ECM. Thirty-two 56-wk-old White Leghorn hens were divided into 4 groups of 8 birds each. They were fed 0 (control, 10, 20 or 30% dietary ECM for 12 weeks. Results: Compared with the control, although the chickens in all the experimental groups consumed less feed (pConclusion: These results indicate that ECM can be a useful feed ingredient in commercial diets for laying hens at levels up to 20%.

  16. Electronic structure and magnetism of layered compounds SrBO2 (B = Ni, Co, Mn): A theoretical investigation

    Science.gov (United States)

    Rahman, Mavlanjan; Zhou, Ke-Chao; Nie, Yao-Zhuang; Guo, Guang-Hua

    2017-10-01

    We investigate the electronic structure and magnetic properties of layered compounds SrBO2 (B = Co, Ni, Mn) based on first principles calculations in the framework of density functional theory with GGA+U method. We compute the phonon dispersion of these compounds to probe the dynamical stability and find that all the compounds are dynamically stable. SrCoO2 and SrNiO2 are G-type antiferromagnetic insulators, and SrMnO2 is an A-type antiferromagnetic conductor. The electronic configurations of 3d orbitals are (dxz)2(dz2)2(dyz)1(dxy)1(dx2-y2)1 and (dxz)2(dyz)2(dz2)2(dxy)1(dx2-y2)1 in SrCoO2 and SrNiO2, respectively. SrCoO2 shows a Jahn-Teller distortion (a>b) because the down-spin Co 3d electron occupies the degenerate (dxz, dyz) levels. Using Monte Carlo simulations based on the Heisenberg model with exchange parameters obtained from first principles calculations, we obtain the Néel temperatures (TN) of SrCoO2 and SrNiO2, which are 249 K and 85 K, respectively.

  17. High pressure measurement of the uniaxial stress of host layers on intercalants and staging transformation of intercalation compounds

    CERN Document Server

    Park, T R; Kim, H; Min, P

    2002-01-01

    A layered double-hydroxide intercalation compound was synthesized to measure the uniaxial stress the host layers exert on the intercalants. To measure the uniaxial stress, we employed the photoluminescence (PL) from the intercalated species, the Sm ion complex, as it is sensitive to the deformation of the intercalants. Of the many PL peaks the Sm ion complex produces, the one that is independent of the counter-cation environment was chosen for the measurement since the Sm ion complexes are placed under a different electrostatic environment after intercalation. The peak position of the PL was redshifted linearly with increasing hydrostatic pressure on the intercalated sample. Using this pressure-induced redshifting rate and the PL difference at ambient pressure between the pre-intercalation and the intercalated ions, we found that, in the absence of external pressure, the uniaxial stress exerted on the samarium ion complexes by the host layers was about 13.9 GPa at room temperature. Time-resolved PL data also ...

  18. Biological adaptation to misfits of immediately loaded fixed prostheses following computer-guided surgery.

    Science.gov (United States)

    Puterman, Israel; Kan, Joseph Y K; Rungcharassaeng, Kitichai; Oyama, Kotaro; Morimoto, Taichiro; Lozada, Jaime

    2012-04-01

    In this clinical report, following computer-guided (3D Procera Software Planning Program, Nobel Biocare, Yorba Linda, CA) placement and immediate provisionalization of 12 dental implants (NobelSpeedy™ Replace, Nobel Biocare), misfits of the prefabricated screw-retained interim prostheses were noted at several implant-abutment junctions. Nevertheless, adaptation of the misfits was observed 10 days later, after the loosened screws were tightened. While a high mean marginal bone loss of 2.1 mm (range: 1.4 to 3.5 mm) was noted, all implants remained osseointegrated at 3-year follow-up.

  19. Pressure induced magneto-structural phase transitions in layered RMn2X2 compounds (invited)

    Science.gov (United States)

    Kennedy, Shane; Wang, Jianli; Campbell, Stewart; Hofmann, Michael; Dou, Shixue

    2014-05-01

    We have studied a range of pseudo-ternaries derived from the parent compound PrMn2Ge2, substituting for each constituent element with a smaller one to contract the lattice. This enables us to observe the magneto-elastic transitions that occur as the Mn-Mn nearest neighbour distance is reduced and to assess the role of Pr on the magnetism. Here, we report on the PrMn2Ge2-xSix, Pr1-xYxMn2Ge2, and PrMn2-xFexGe2 systems. The pressure produced by chemical substitution in these pseudo-ternaries is inherently non-uniform, with local pressure variations dependent on the local atomic distribution. We find that concentrated chemical substitution on the R or X site (e.g., in Pr0.5Y0.5Mn2Ge2 and PrMn2Ge0.8Si1.2) can produce a separation into two distinct magnetic phases, canted ferromagnetic and canted antiferromagnetic, with a commensurate phase gap in the crystalline lattice. This phase gap is a consequence of the combination of phase separation and spontaneous magnetostriction, which is positive on transition to the canted ferromagnetic phase and negative on transition to the canted antiferromagnetic phase. Our results show that co-existence of canted ferromagnetic and antiferromagnetic phases depends on chemical pressure from the rare earth and metalloid sites, on local lattice strain distributions and on applied magnetic field. We demonstrate that the effects of chemical pressure bear close resemblance to those of mechanical pressure on the parent compound.

  20. STRESS ANALYSIS AND BURST PRESSURE DETERMINATION OF TWO LAYER COMPOUND PRESSURE VESSEL

    Directory of Open Access Journals (Sweden)

    HARERAM LOHAR

    2013-02-01

    Full Text Available Multilayer pressure vessel is designed to work under high-pressure condition. This paper introduces the stress analysis and the burst pressure calculation of a two-layer shrink fitted pressure vessel. In the shrink-fitting problems, considering long hollow cylinders, the plane strain hypothesis can be regarded as more natural. Generally hoops stress distribution is non-linear and sharply reduced toward the outer surface. By shrink fitting concentric shells towards the inner shells are placed in residual compression so that the initial compressive hoop stress must be relieved by internal pressure before hoop tensile stress are developed. Therefore the maximum hoop stress will be reduced, resulting more burst pressure. The analytical results of stress distribution and burst pressure is calculated and validated by ANSYS Workbench results.

  1. Slow relaxation of the magnetization observed in an antiferromagnetically ordered phase for SCM-based two-dimensional layered compounds.

    Science.gov (United States)

    Kagesawa, Koichi; Nishimura, Yuki; Yoshida, Hiroki; Breedlove, Brian K; Yamashita, Masahiro; Miyasaka, Hitoshi

    2017-03-07

    Two-dimensional layered compounds with different counteranions, [{Mn(salen)}4C6](BF4)2·2(CH3OH) (1) and [{Mn(salen)}4C6](PF6)2·2(CH3OH) (2) (salen(2-) = N,N'-bis(salicylideneiminato), C6(2-) = C6H12(COO)2(2-)), were synthesized by assembling [Mn(salen)(H2O)]X (X(-) = BF4(-) and PF6(-)) and C6H12(CO2(-))2 (C6(2-)) in a methanol/2-propanol medium. The compounds have similar structures, which are composed of Mn(salen) out-of-plane dimers bridged by μ(4)-type C6(2-) ions, forming a brick-wall-type network of [-{Mn2}-OCO-] chains alternately connected via C6H12 linkers of C6(2-) moieties. The counteranions for 1 and 2, i.e., BF4(-) and PF6(-), respectively, are located between layers. Since the size of BF4(-) is smaller than that of PF6(-), intra-layer inter-chain and inter-plane nearest-neighbor MnMn distances are shorter in 1 than in 2. The zigzag chain moiety of [-{Mn2}-OCO-] leads to a canted S = 2 spin arrangement with ferromagnetic coupling in the Mn(III) out-of-plane dimer moiety and antiferromagnetic coupling through -OCO- bridges. Due to strong uniaxial anisotropy of the Mn(III) ion, the [-{Mn2}-OCO-] chains could behave as a single-chain magnet (SCM), which exhibits slow relaxation of magnetization at low temperatures. Nevertheless, these compounds fall into an antiferromagnetic ground state at higher temperatures of TN = 4.6 and 3.8 K for 1 and 2, respectively, than active temperatures for SCM behavior. The spin flip field at 1.8 K is 2.7 and 1.8 kOe for 1 and 2, respectively, which is attributed to the inter-chain interactions tuned by the size of the counteranions. The relaxation times of magnetization become longer at the boundary between the antiferromagnetic phase and the paramagnetic phase.

  2. Structural phase transition and superlattice misfit strain of RFeAsO (R=La,Pr,Nd,Sm)

    Science.gov (United States)

    Ricci, A.; Poccia, N.; Joseph, B.; Barba, L.; Arrighetti, G.; Ciasca, G.; Yan, J.-Q.; McCallum, R. W.; Lograsso, T. A.; Zhigadlo, N. D.; Karpinski, J.; Bianconi, A.

    2010-10-01

    The tetragonal-to-orthorhombic structural phase transition (SPT) in LaFeAsO (La-1111) and SmFeAsO (Sm-1111) single crystals measured by high-resolution x-ray diffraction is found to be sharp while the RFeAsO (R=La,Nd,Pr,Sm) polycrystalline samples show a broad continuous SPT. Comparing the polycrystalline and the single-crystal 1111 samples, the critical exponents of the SPT are found to be the same while the correlation length critical exponents are found to be very different. These results imply that the lattice fluctuations in 1111 systems change in samples with different surface to volume ratio that is assigned to the relieve of the temperature-dependent superlattice misfit strain between active iron layers and the spacer layers in 1111 systems. This phenomenon that is missing in the AFe2As2 (A=Ca,Sr,Ba) “122” systems, with the same electronic structure but different for the thickness and the elastic constant of the spacer layers, is related with the different maximum superconducting transition temperature in the 1111 (55 K) versus 122 (35 K) systems and implies the surface reconstruction in 1111 single crystals.

  3. Compound surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a structurally chiral material

    CERN Document Server

    Chiadini, Francesco; Scaglione, Antonio; Lakhtakia, Akhlesh

    2015-01-01

    Multiple compound surface plasmon-polariton (SPP) waves can be guided by a structure consisting of a sufficiently thick layer of metal sandwiched between a homogeneous isotropic dielectric (HID) material and a dielectric structurally chiral material (SCM). The compound SPP waves are strongly bound to both metal/dielectric interfaces when the thickness of the metal layer is comparable to the skin depth but just to one of the two interfaces when the thickness is much larger. The compound SPP waves differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. Some compound SPP waves are not greatly affected by the choice of the direction of propagation in the transverse plane but others are, depending on metal thickness. For fixed metal thickness, the number of compound SPP waves depends on the relative permittivity of the HID material, which can be useful for sensing applications.

  4. Compound microstructures and wax layer of beetle elytral surfaces and their influence on wetting properties.

    Directory of Open Access Journals (Sweden)

    Mingxia Sun

    Full Text Available A beetles' first line of defense against environmental hazards is their mesothoracic elytra--rigid, protective forewings. In order to study the interaction of these wings with water, the surface microstructures of various beetles' elytra were observed by Environment Scanning Electron Microscopy (ESEM and Atomic Force Microscopy (AFM. Chemistry components were ascertained using X-ray photoelectron spectroscopy (XPS. All the beetles of various habitats (including desert, plant, dung, land and water exhibited compound microstructures on their elytra. The wetting properties of these elytra were identified using an optical contact angle meter. In general the native elytra exhibited hydrophilic or weak hydrophobic properties with contact angles (CAs ranging from 47.5° to 109.1°. After treatment with chloroform, the CAs all increased on the rougher elytral surfaces. The presence of wax is not the only determinant of hydrophobic properties, but rather a combination with microscopic structures found on the surfaces. Irregularities and the presence or absence of tiny cracks, hairs (or setae, pores and protrusions are important factors which influence the wetting properties. Rougher elytral surfaces tended to present a stronger hydrophobicity. Effects on hydrophobicity, such as surface microstructures, chemistry, environment and aging (referring to the time after emergence, are also included and discussed. Our results also provide insights into the motion of water droplets when in contact with beetle elytra.

  5. Study of bipolar pulsed plasma electrolytic carbonitriding on nanostructure of compound layer for a gamma Ti-Al alloy

    Institute of Scientific and Technical Information of China (English)

    Mahmood ALIOFKHAZRAEI; Alireza SABOUR ROUHAGHDAM; Mohsen ROOHZENDEH

    2008-01-01

    The surface hardening of a gamma Ti-Al alloy by using bipolar pulsed nanocrystalline plasma electro-lytic carbonitriding has been studied in this investigation. Coating process was performed on a triethanolamine-based electrolyte by a cooling bath. The nanostructure of the obtained compound layer was examined with the figure analysis of the scanning electron microscopy (SEM) nanographs. The effects of the process variables, i.e., fre-quency, temperature of the electrolyte, applied voltage and treatment time, have been experimentally studied. Statistical methods were used to achieve the optimum size of the nanocrystals. Finally, the contribution percentage of the effective factors of the pulsed current was revealed, and the confirmation run showed the validity of the obtained results.

  6. Laughter from Realism to Modernism : Misfits and Humorists in Pirandello, Svevo, Palazzeschi, and Gadda

    NARCIS (Netherlands)

    Godioli, Alberto

    2015-01-01

    As best exemplified by the works of Pirandello, Svevo, Palazzeschi, and Gadda, Italian modernist fiction is particularly rich in bizarre and ludicrous characters, whose originality is often derided by a uniform society. On the other hand, laughter can also be used by the author (or by the misfits th

  7. Laughter from Realism to Modernism : Misfits and Humorists in Pirandello, Svevo, Palazzeschi, and Gadda

    NARCIS (Netherlands)

    Godioli, Alberto

    2015-01-01

    As best exemplified by the works of Pirandello, Svevo, Palazzeschi, and Gadda, Italian modernist fiction is particularly rich in bizarre and ludicrous characters, whose originality is often derided by a uniform society. On the other hand, laughter can also be used by the author (or by the misfits

  8. Laughter from Realism to Modernism : Misfits and Humorists in Pirandello, Svevo, Palazzeschi, and Gadda

    NARCIS (Netherlands)

    Godioli, Alberto

    2015-01-01

    As best exemplified by the works of Pirandello, Svevo, Palazzeschi, and Gadda, Italian modernist fiction is particularly rich in bizarre and ludicrous characters, whose originality is often derided by a uniform society. On the other hand, laughter can also be used by the author (or by the misfits th

  9. Using the Bootstrap Method to Evaluate the Critical Range of Misfit for Polytomous Rasch Fit Statistics.

    Science.gov (United States)

    Seol, Hyunsoo

    2016-06-01

    The purpose of this study was to apply the bootstrap procedure to evaluate how the bootstrapped confidence intervals (CIs) for polytomous Rasch fit statistics might differ according to sample sizes and test lengths in comparison with the rule-of-thumb critical value of misfit. A total of 25 simulated data sets were generated to fit the Rasch measurement and then a total of 1,000 replications were conducted to compute the bootstrapped CIs under each of 25 testing conditions. The results showed that rule-of-thumb critical values for assessing the magnitude of misfit were not applicable because the infit and outfit mean square error statistics showed different magnitudes of variability over testing conditions and the standardized fit statistics did not exactly follow the standard normal distribution. Further, they also do not share the same critical range for the item and person misfit. Based on the results of the study, the bootstrapped CIs can be used to identify misfitting items or persons as they offer a reasonable alternative solution, especially when the distributions of the infit and outfit statistics are not well known and depend on sample size.

  10. Misfit strain driven cation inter-diffusion across an epitaxial multiferroic thin film interface

    Science.gov (United States)

    Sankara Rama Krishnan, P. S.; Morozovska, Anna N.; Eliseev, Eugene A.; Ramasse, Quentin M.; Kepaptsoglou, Demie; Liang, Wen-I.; Chu, Ying-Hao; Munroe, Paul; Nagarajan, V.

    2014-02-01

    Cation intermixing at functional oxide interfaces remains a highly controversial area directly relevant to interface-driven nanoelectronic device properties. Here, we systematically explore the cation intermixing in epitaxial (001) oriented multiferroic bismuth ferrite (BFO) grown on a (001) lanthanum aluminate (LAO) substrate. Aberration corrected dedicated scanning transmission electron microscopy and electron energy loss spectroscopy reveal that the interface is not chemically sharp, but with an intermixing of ˜2 nm. The driving force for this process is identified as misfit-driven elastic strain. Landau-Ginzburg-Devonshire-based phenomenological theory was combined with the Sheldon and Shenoy formula in order to understand the influence of boundary conditions and depolarizing fields arising from misfit strain between the LAO substrate and BFO film. The theory predicts the presence of a strong potential gradient at the interface, which decays on moving into the bulk of the film. This potential gradient is significant enough to drive the cation migration across the interface, thereby mitigating the misfit strain. Our results offer new insights on how chemical roughening at oxide interfaces can be effective in stabilizing the structural integrity of the interface without the need for misfit dislocations. These findings offer a general formalism for understanding cation intermixing at highly strained oxide interfaces that are used in nanoelectronic devices.

  11. Two-Dimensional Superconductor with a Giant Rashba Effect: One-Atom-Layer Tl-Pb Compound on Si(111)

    Science.gov (United States)

    Matetskiy, A. V.; Ichinokura, S.; Bondarenko, L. V.; Tupchaya, A. Y.; Gruznev, D. V.; Zotov, A. V.; Saranin, A. A.; Hobara, R.; Takayama, A.; Hasegawa, S.

    2015-10-01

    A one-atom-layer compound made of one monolayer of Tl and one-third monolayer of Pb on a Si(111) surface having √{3 }×√{3 } periodicity was found to exhibit a giant Rashba-type spin splitting of metallic surface-state bands together with two-dimensional superconducting transport properties. Temperature-dependent angle-resolved photoelectron spectroscopy revealed an enhanced electron-phonon coupling for one of the spin-split bands. In situ micro-four-point-probe conductivity measurements with and without magnetic field demonstrated that the (Tl, Pb)/Si(111) system transformed into the superconducting state at 2.25 K, followed by the Berezinskii-Kosterlitz-Thouless mechanism. The 2D Tl-Pb compound on Si(111) is believed to be the prototypical object for prospective studies of intriguing properties of the superconducting 2D system with lifted spin degeneracy, bearing in mind that its composition, atomic and electron band structures, and spin texture are already well established.

  12. A novel Whole Air Sample Profiler (WASP for the quantification of volatile organic compounds in the boundary layer

    Directory of Open Access Journals (Sweden)

    J. E. Mak

    2013-10-01

    Full Text Available The emission and fate of reactive volatile organic compounds (VOCs is of inherent interest to those studying chemical biosphere–atmosphere interactions. In-canopy VOC observations are obtainable using tower-based samplers, but the lack of suitable sampling systems for the full boundary layer has limited the availability of data characterizing the vertical structure of such gases above the canopy height and still in the boundary layer. This is an important region where many reactive VOCs are oxidized or otherwise removed. Here we describe an airborne sampling system designed to collect a vertical profile of air into a 3/8 in. OD (outer diameter tube 150 m in length. The inlet ram air pressure is used to flow sampled air through the tube, which results in a varying flow rate based on aircraft speed and altitude. Since aircraft velocity decreases during ascent, it is necessary to account for the variable flow rate into the tube. This is accomplished using a reference gas that is pulsed into the air stream so that the precise altitude of the collected air can be reconstructed post-collection. The pulsed injections are also used to determine any significant effect from diffusion/mixing within the sampling tube, either during collection or subsequent extraction for gas analysis. This system has been successfully deployed, and we show some measured vertical profiles of isoprene and its oxidation products methacrolein and methyl vinyl ketone from a mixed canopy near Columbia, Missouri.

  13. Magnetic behavior of Gd3Ru4Al12, a layered compound with distorted kagomé net

    Science.gov (United States)

    Chandragiri, Venkatesh; Iyer, Kartik K.; Sampathkumaran, E. V.

    2016-07-01

    The magnetic behavior of the compound, Gd3Ru4Al12, which was reported about two decades ago to crystallize in a hexagonal structure (space group P63/mmc), has not been investigated in the past literature despite interesting structural features (that is, magnetic layers and triangular as well as kagomé-lattice features favoring frustrated magnetism) characterizing this compound. We report here the results of studies of magnetization, heat capacity and magnetoresistance in the temperature range T  =  1.8-300 K. The results establish that there is a long-range magnetic order of antiferromagnetic type below (T N  =) 18.5 K, despite a much larger value (~80 K) of paramagnetic Curie temperature with a positive sign characteristic of ferromagnetic interaction. We attribute this to geometric frustration. The most interesting finding is that there is an additional magnetic anomaly below ~55 K before the onset of long-range order in the magnetic susceptibility data. Concurrent with this observation, the sign of isothermal change in entropy, ΔS  =  S(0)  -  S(H), where H is the externally applied magnetic field, remains positive above T N, with a broad peak. This observation indicates the presence of ferromagnetic clusters before the onset of long-range magnetic order. Thus, this compound may serve as an example of a situation in which magnetic frustration due to geometrical reasons faces competition from such magnetic precursor effects. There is also a reversal of the sign of  -ΔS in the curves for lower final fields (H  behavior is consistent with the above conclusions.

  14. An experimental study on the preparation of tochilinite-originated intercalation compounds comprised of Fe 1-xS host layers and various kinds of guest layers

    Science.gov (United States)

    Peng, Yiya; Xi, Guangcheng; Zhong, Chang; Wang, Linping; Lu, Jun; Sun, Ximeng; Zhu, Lu; Han, Qikun; Chen, Lin; Shi, Lei; Sun, Mei; Li, Qianrong; Yu, Min; Yin, Mingwen

    2009-08-01

    Tochilinite represents a mineral group of ordered mixed-layer structures containing alternating Fe 1-xS layers with mackinawite-like structure and metal hydroxide layers with Mg(OH) 2-like structure. In this article, we report the preparation of a series of tochilinite-originated (or Fe 1-xS-based) intercalation compounds (ICs). According to their preparation procedures, these ICs can be divided into four kinds. The first kind of IC was sodium tochilinite (Na-tochilinite), which was prepared by the hydrothermal reaction of metallic Fe particles with concentrated Na 2S·9H 2O aqueous solutions. The hydroxide layer of the Na-tochilinite was a mixed hydroxide of Na + ions along with a certain amount of Fe 2+ ions. When the hydroxide layer of the Na-tochilinite completely dissolved in aqueous solutions, a Fe-deficient mackinawite-like phase Fe 1-xS was obtained, which was probably an electron-deficient p-type conductor. The second kind of ICs was prepared by 'low-temperature direct intercalation in aqueous solutions, using Na-tochilinite as a parental precursor. When the Na-tochilinite was ultrasonicated in aqueous solutions containing Lewis basic complexing agents (like NH 3, N 2H 4, 2,2'-bipyridine (bipy), and 1,10-phenanthroline (phen)), the Na + ions of the Na-tochilinite were removed and the Lewis basic complexing agents entered the hydroxide layer of the Na-tochilinite and became coordinated with the Fe 2+ ions, and the second kind of ICs was thus produced. The second kind of ICs includes NH 3 IC, N 2H 4 IC, N 2H 4-NH 3 IC, [Fe(bipy) 3] 2+-containing IC and [Fe(phen) 3] 2+-containing IC. The third kind of ICs, which includes NH 3 IC, N 2H 4-NH 3 IC and N 2H 4-LiOH (NaOH) IC, was prepared by the hydrothermal reaction of metallic Fe particles with (NH 4) 2S aqueous solution, S (elemental) + N 2H 4·H 2O aqueous solution, and S + N 2H 4·H 2O + LiOH (NaOH) aqueous solution, respectively. The third kind of ICs has a close relationship with the second kind of ICs both

  15. Study on Friction and Wear Characteristics and Structure of Compound Layer from Combined Treatment of Ion Nitrocarburizing-Ion Sulphurizing of CrMoCu Alloy Cast Iron

    Institute of Scientific and Technical Information of China (English)

    MA Shi-ning; HU Chun-hua; LI Xin; QIU Ji

    2004-01-01

    The technics of combined treatment of ion nitrocarburizing-ion sulphurizing of CrMoCu alloy cast iron has been investigated and the compound layer with nitrocarbonide and sulphide has been made on the surface of CrMoCu alloy cast iron. The compound layer is composed of sulfide surface layer and the nitrocarbonide hypo-surface layer and its diffusing layer. The size of sulfide globular grains distributing equably on the surface is in nano-micron-scale, and the phase structure of the compound layer is composed of FeS、 FeS2、 Fe2C and Fe3N. Under dry sliding condition, the friction-reducing of sulphurized surface is good, but its function time can't last very long. The nitrocarbonided+sulphurized surface can greatly improve the wear-resistance and the friction-reducing of CrMoCu alloy cast iron, and its integrated friction and wear properties are better than plain and sulphurized surfaces'.

  16. Large scale simulations of the mechanical properties of layered transition metal ternary compounds for fossil energy power system applications

    Energy Technology Data Exchange (ETDEWEB)

    Ching, Wai-Yim [Univ. of Missouri, Kansas City, MO (United States)

    2014-12-31

    Advanced materials with applications in extreme conditions such as high temperature, high pressure, and corrosive environments play a critical role in the development of new technologies to significantly improve the performance of different types of power plants. Materials that are currently employed in fossil energy conversion systems are typically the Ni-based alloys and stainless steels that have already reached their ultimate performance limits. Incremental improvements are unlikely to meet the more stringent requirements aimed at increased efficiency and reduce risks while addressing environmental concerns and keeping costs low. Computational studies can lead the way in the search for novel materials or for significant improvements in existing materials that can meet such requirements. Detailed computational studies with sufficient predictive power can provide an atomistic level understanding of the key characteristics that lead to desirable properties. This project focuses on the comprehensive study of a new class of materials called MAX phases, or Mn+1AXn (M = a transition metal, A = Al or other group III, IV, and V elements, X = C or N). The MAX phases are layered transition metal carbides or nitrides with a rare combination of metallic and ceramic properties. Due to their unique structural arrangements and special types of bonding, these thermodynamically stable alloys possess some of the most outstanding properties. We used a genomic approach in screening a large number of potential MAX phases and established a database for 665 viable MAX compounds on the structure, mechanical and electronic properties and investigated the correlations between them. This database if then used as a tool for materials informatics for further exploration of this class of intermetallic compounds.

  17. Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation

    Science.gov (United States)

    Jiang, Suihe; Wang, Hui; Wu, Yuan; Liu, Xiongjun; Chen, Honghong; Yao, Mengji; Gault, Baptiste; Ponge, Dirk; Raabe, Dierk; Hirata, Akihiko; Chen, Mingwei; Wang, Yandong; Lu, Zhaoping

    2017-04-01

    Next-generation high-performance structural materials are required for lightweight design strategies and advanced energy applications. Maraging steels, combining a martensite matrix with nanoprecipitates, are a class of high-strength materials with the potential for matching these demands. Their outstanding strength originates from semi-coherent precipitates, which unavoidably exhibit a heterogeneous distribution that creates large coherency strains, which in turn may promote crack initiation under load. Here we report a counterintuitive strategy for the design of ultrastrong steel alloys by high-density nanoprecipitation with minimal lattice misfit. We found that these highly dispersed, fully coherent precipitates (that is, the crystal lattice of the precipitates is almost the same as that of the surrounding matrix), showing very low lattice misfit with the matrix and high anti-phase boundary energy, strengthen alloys without sacrificing ductility. Such low lattice misfit (0.03 ± 0.04 per cent) decreases the nucleation barrier for precipitation, thus enabling and stabilizing nanoprecipitates with an extremely high number density (more than 1024 per cubic metre) and small size (about 2.7 ± 0.2 nanometres). The minimized elastic misfit strain around the particles does not contribute much to the dislocation interaction, which is typically needed for strength increase. Instead, our strengthening mechanism exploits the chemical ordering effect that creates backstresses (the forces opposing deformation) when precipitates are cut by dislocations. We create a class of steels, strengthened by Ni(Al,Fe) precipitates, with a strength of up to 2.2 gigapascals and good ductility (about 8.2 per cent). The chemical composition of the precipitates enables a substantial reduction in cost compared to conventional maraging steels owing to the replacement of the essential but high-cost alloying elements cobalt and titanium with inexpensive and lightweight aluminium

  18. Structural and magnetic properties of the layered compound Ca2.375La0.125Sr0.5GaMn2O8

    Indian Academy of Sciences (India)

    A K Bera; S M Yusuf; A Jain

    2008-11-01

    The brownmillerite-type layered compound Ca2.375La0.125Sr0.5GaMn2O8 has been synthesized. The crystal and magnetic structures have been refined by the Rietveld analysis of the neutron powder diffraction patterns at 300 and 20 K. This compound crystallizes in the orthorhombic symmetry under the space group Pcm21 ( = 5.447(2), = 11.359(4) and = 5.322(2) Å). The compound is found to be antiferromagnetic at 20 K. The ordered Mn magnetic moment, aligned along the crystallographic -direction, is derived to be 2.53(5) per Mn ion at 20 K.

  19. A new layer compound Nb{sub 4}SiC{sub 3} predicted from first-principles theory

    Energy Technology Data Exchange (ETDEWEB)

    Li Chenliang [School of Astronautics, Harbin Institute of Technology, Harbin (China); Kuo Jeilai [School of Physics and Mathematical Sciences, Nanyang Technological University (Singapore); Wang, Biao [School of Physics and Engineering, Sun Yat-Sen University, Guangzhou (China); Li Yuanshi [Department of Cardiology, First Clinical College, Harbin Medical University, Harbin (China); Wang Rui, E-mail: lichenliang1980@yahoo.com.c [Department of Applied Chemistry, Harbin Institute of Technology, Harbin (China)

    2009-04-07

    We predicted a new layer compound Nb{sub 4}SiC{sub 3} using the first-principles method. The structural stability, mechanical, electronic, theoretical hardness and optical properties of Nb{sub 4}SiC{sub 3} were investigated. A stable Nb{sub 4}SiC{sub 3} phase appears in the {alpha}-type crystal structure. Moreover, the predicted Nb{sub 4}SiC{sub 3} is a metal and exhibits covalent nature. Nb{sub 4}SiC{sub 3} has a theoretical hardness of 10.86 GPa, which is much higher than Nb{sub 4}AlC{sub 3}; at the same time, it is more ductile than Nb{sub 4}AlC{sub 3}. The strong covalent bonding in Nb{sub 4}SiC{sub 3} is responsible for its high bulk modulus and hardness. Nb{sub 4}SiC{sub 3} exhibits slightly anisotropic elasticity. Furthermore, its optical properties are also analysed in detail. It is shown that Nb{sub 4}SiC{sub 3} might be a better candidate material as a coating to avoid solar heating than Ti{sub 4}AlN{sub 3}.

  20. Compound surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a periodically multilayered isotropic dielectric material

    CERN Document Server

    Chiadini, Francesco; Scaglione, Antonio; Lakhtakia, Akhlesh

    2015-01-01

    Multiple p- and s-polarized compound surface plasmon-polariton (SPP) waves at a fixed frequency can be guided by a structure consisting of a metal layer sandwiched between a homogeneous isotropic dielectric (HID) material and a periodic multilayered isotropic dielectric (PMLID) material. For any thickness of the metal layer, at least one compound SPP wave must exist. It possesses the p-polarization state, is strongly bound to the metal/HID interface when the metal thickness is large but to both metal/dielectric interfaces when the metal thickness is small. When the metal layer vanishes, this compound SPP wave transmutes into a Tamm wave. Additional compound SPP waves exist, depending on the thickness of the metal layer, the relative permittivity of the HID material, and the period and the composition of the PMLID material. Some of these are p polarized, the others being s polarized. All of them differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. The...

  1. Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy.

    Science.gov (United States)

    Hierro-Rodriguez, A; Cid, R; Vélez, M; Rodriguez-Rodriguez, G; Martín, J I; Álvarez-Prado, L M; Alameda, J M

    2012-09-14

    Stripe domains are studied in perpendicular magnetic anisotropy films nanostructured with a periodic thickness modulation that induces the lateral modulation of both stripe periods and in-plane magnetization. The resulting system is the 2D equivalent of a strained superlattice with properties controlled by interfacial misfit strain within the magnetic stripe structure and shape anisotropy. This allows us to observe, experimentally for the first time, the continuous structural transformation of a grain boundary in this 2D magnetic crystal in the whole angular range. The magnetization reversal process can be tailored through the effect of misfit strain due to the coupling between disclinations in the magnetic stripe pattern and domain walls in the in-plane magnetization configuration.

  2. Mechanoresponsive change in photoluminescent color of rod-like liquid-crystalline compounds and control of molecular orientation on photoaligned layer

    Science.gov (United States)

    Kondo, Mizuho; Miura, Seiya; Okumoto, Kentaro; Hashimoto, Mayuko; Fukae, Ryohei; Kawatsuki, Nobuhiro

    2014-10-01

    In this paper, we reported novel liquid-crystalline luminophore that switches its photoluminescent color by mechanically grinding. Mechanochromic luminescence (MCL) is expected for mechanical sensor, cellular imaging, detection of microenvironmental changes, and optical memory. In this work, we focused on liquid-crystalline MCL compounds on alignment layer. Controlling the molecular alignment of MCL compounds with photoalignment layer have potential to succeed in functional MCL film such as polarized micropatterned MCL and directional detection of mechanical stimuli. Herein, we prepared asymmetric rodlike MCL compounds containing cyano- and pyridyl molecular terminal and explored their photoluminescence behavior under mechanical stimulus. The cyano terminated compound showed a nematic phase and tuned its photoluminescent color from green to yellow upon grinding, while the pyridyl-terminated compounds that show no mesophase changed its photoluminescent color from blue to green and reverted to its initial color by heating above its melting point. The cyano-terminated MCL was aligned along the orientation direction of photoalignment layer and pyridyl-terminated MCL exhibited uniaxial alignment when it coated on photoaligned film containing carboxylic acid.

  3. Study on Friction and Wear Characteristics and Structure of Compound Layer from Combined Treatment of Ion Nitrocarburizing-Ion Sulphurizing of CrMoCu Alloy Cast Iron

    Institute of Scientific and Technical Information of China (English)

    MAShi-ning; HUChun-hua; LIXin; QIUJi

    2004-01-01

    The technics of combined treatment of ion nitrocarburizing-ion sulpburizing of CrMoCu alloy cast iron has been investigated and the compound layer with nitrocabonide and sulphide has been made on the surface of CrMoCu alloy cast iron. The compound layer is composed of sulfide surface layer and the nitrocarbonide hypo-surface layer and its diffusing laye. The size of sulfide globular grains distributing equably on the surface is in nano-micmn-scale, and the phase structure of the compound layer is composed of FeS, FeS2, Fe2C and FerN. Under dry sliding condition, the friction-reducing of sulphurized surface is good, but its function time can't last vet3. long, The nitrocarbonided+sulphurized surface can gready improve the wear-resistance and the friction-reducing of CrMoCu alloy cast iron, and its integrated friction and wear properties are better than plain and sulphurized surfaces.

  4. Two isostructural layered oxohalide compounds containing Mn{sup 2+}, Te{sup 4+} and Si{sup 4+}; crystal structure and magnetic susceptibility

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, Iwan [Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden); Kremer, Reinhard K. [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Johnsson, Mats, E-mail: mats.johnsson@mmk.su.se [Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden)

    2014-10-15

    The new compounds Mn{sub 4}(TeO{sub 3})(SiO{sub 4})X{sub 2} (X=Br, Cl) were synthesized by solid state reactions in sealed evacuated silica tubes. The compounds crystallize in the monoclinic space group P2{sub 1}/m with the unit cell parameters a=5.5463(3) Å (5.49434(7) Å), b=6.4893(4) Å (6.44184(9) Å), c=12.8709(7) Å (12.60451(18) Å), β=93.559(5)° (94.1590(12)°) and Z=2 for the respective Br and Cl analogues. Manganese adopts various distorted coordination polyhedra; [MnO{sub 6}] octahedra, [MnO{sub 5}] tetragonal pyramids and [MnO{sub 2}X{sub 2}] tetrahedra. Other building blocks are [SiO{sub 4}] tetrahedra and [TeO{sub 3}] trigonal pyramids. The structure is made up from layers having no net charge that are connected via weak Van der Waal interactions. The layers that are parallel to (1 1 0) consist of two manganese oxide sheets which are separated by [SiO{sub 4}] tetrahedra. On the outer sides of the sheets are the [MnO{sub 2}X{sub 2}] tetrahedra and the [TeO{sub 3}] trigonal pyramids connected so that the halide ions and the stereochemically active lone pairs on the tellurium atoms protrude from the layers. Magnetic susceptibility measurements reveal a Curie law with a Weiss temperature of θ=−153(3) K for temperatures ≥100 K and indicate antiferromagnetic ordering at T{sub N} ∼4 K. Possible structural origins of the large frustration parameter of f=38 are discussed. - Graphical abstract: Table of contents caption. The new compounds Mn{sub 4}(TeO{sub 3})(SiO{sub 4})X{sub 2} (X=Br, Cl) are layered with weak Van der Waal interactions in between the layers. Manganese adopts various distorted coordination polyhedral, other building blocks are [SiO{sub 4}] tetrahedra and [TeO{sub 3}] trigonal pyramids. Magnetic susceptibility measurements indicate antiferromagnetic ordering at low temperatures and a large frustration parameter. - Highlights: • Two new isostructural oxohalide compounds are described. • The compounds are the first examples of

  5. Revealing dynamics and consequences of fit and misfit between formal and informal networks in multi-institutional product development collaborations

    NARCIS (Netherlands)

    Kratzer, J.; Gemuenden, Hans G.; Lettl, Christopher

    2008-01-01

    The study presents a longitudinal examination about dynamics and consequences of fit and misfit between formally ascribed design interfaces and informal communication networks in two large multi-institutional product development collaborations in space industry. Findings: (1) formally ascribed desig

  6. Three dimensionally honeycomb layered double hydroxides framework as a novel fiber coating for headspace solid-phase microextraction of phenolic compounds.

    Science.gov (United States)

    Abolghasemi, Mir Mahdi; Yousefi, Vahid

    2014-06-06

    A new solid phase microextraction (SPME) fiber based on high-temperature three dimensionally honeycomb layered double hydroxide (TDH-LDH) material is presented. The fiber coating can be prepared easily, it is mechanically stable and exhibits relatively high thermal stability. This study shows that three dimensionally honeycomb layered double hydroxide generated porous morphology. The TDH-LDH material was tested for the extraction of some phenolic and polycyclic aromatic hydrocarbon compounds from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). The TDH-LDH fiber contains polar groups and its efficiency for non-polar polycyclic aromatic hydrocarbon compounds was lower than phenolic compounds. On the other hand, a high tendency towards the adsorption of polar phenolic compounds was observed for the proposed fiber. The effects of the extraction and desorption parameters including extraction temperature, extraction time, ionic strength, stirring rate, pH and desorption temperature and time have been studied. In optimum conditions, the repeatability for one fiber (n=5), expressed as relative standard deviation (R.S.D. %), was between 2.8% and 7.1% for the phenolic compounds. The detection limits for the studied phenolic compounds were between 0.02 and 5.8 ng mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis.

  7. Heterointegration of III-V on silicon using a crystalline oxide buffer layer

    Science.gov (United States)

    Bhatnagar, K.; Rojas-Ramirez, J. S.; Contreras-Guerrero, R.; Caro, M.; Droopad, R.

    2015-09-01

    The integration of III-V compound semiconductors with Si can combine the cost advantage and maturity of Si technology with the superior performance of III-V materials. We have achieved the heteroepitaxial growth of III-V compound semiconductors on a crystalline SrTiO3 buffer layer grown on Si(0 0 1) substrates. A two-step growth process utilizing a high temperature nucleation layer of GaAs, followed by a low-temperature GaAs layer at a higher growth rate was employed to achieve highly crystalline thick GaAs layers on the SrTiO3/Si substrates with low surface roughness as seen by AFM. The effect of the GaAs nucleation layer on different surface terminations for the SrTiO3 layer was studied for both on axis and miscut wafers, which led to the conclusion that the Sr terminated surface on miscut substrates provides the best GaAs films. Using GaAs/STO/Si as virtual substrates, we have optimized the growth of high quality GaSb using the interfacial misfit (IMF) dislocation array technique. This work can lead to the possibility of realizing infrared detectors and next-generation high mobility III-V CMOS within the existing Si substrate infrastructure.

  8. pH-dependent assembly of two inorganic-organic hybrid compounds based on octamolybdates: an unusual intercalated layer and a 3D 4-connected framework.

    Science.gov (United States)

    Liu, Hai-Yan; Yang, Jin; Liu, Ying-Ying; Ma, Jian-Fang

    2012-09-07

    Two novel inorganic-organic hybrid compounds based on octamolybdates, namely, [Cu(H(2)L)(2)(γ-Mo(8)O(26))]·(Mo(6)O(19))·2H(2)O (1) and [Cu(H(2)L)(γ-Mo(8)O(26))(H(2)O)(2)]·5H(2)O (2), where L = 1,1'-(1,5-pentanediyl)bis[2-(4-pyridyl)benzimidazole], have been successfully synthesized at different pH values under hydrothermal conditions. Compound 1, which is hydrothermally prepared at pH ≈ 3.5, exhibits an entirely new type of intercalated layer. The nanosized hexamolybdate anions as guests are introduced into the layers. When the pH value is adjusted to 2, a structurally-different complex 2 was obtained. Compound 2 shows a unique 3D 4-connected framework constructed by inorganic layers and H(2)L(2+) ligands as bridges. The two compounds were characterized by elemental analyses, IR spectra and TGA. In addition, the electrochemical properties of 1-modified carbon paste electrode (CPE) have also been investigated in 1 M H(2)SO(4) aqueous solution.

  9. MBE Growth of Highly Relaxed Si0.45 Ge0.55 Films with Very Low Misfit Dislocation Density on Si (001) Substrates

    Institute of Scientific and Technical Information of China (English)

    LU Xiang-Dong; ZHANG Xiang-Jiu; YANG Hong-Bin; Fan Yong-Liang; HUANG Wei-Ning; SUN Yan-Qing

    2006-01-01

    We investigate the molecular-beam-epitaxy growth of highly relaxed Si0.45Ge0.55 films with very low dislocation densities. By using the Si3N4 film as the mask material, the Si0.45Ge0.55 film can be grown on a compositionally stepwise graded SiGe buffer layer in 3μm×3μm windows on a Si (001) substrate. Raman scattering spectroscopy measurement shows that more than 90% strain of the Si0.45Ge0.55 film is relaxed, and almost neither misfit dislocation lines nor etch pits of thread dislocations could be observed when the sample is etched by the modified Schimmel etchant. We suggest that the results can be explained by influence of the edge-induced strain relaxation of the epitaxial film and the edge-induced stress of the mask material.

  10. Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire. II. Electron energy loss spectroscopic study

    Directory of Open Access Journals (Sweden)

    Sung Bo Lee

    2015-07-01

    Full Text Available In Part I, we have shown that the addition of Si into sapphire by ion implantationmakes the sapphire substrate elastically softer than for the undoped sapphire. The more compliant layer of the Si-implanted sapphire substrate can absorb the misfit stress at the GaN/sapphire interface, which produces a lower threading-dislocation density in the GaN overlayer. Here in Part II, based on experimental results by electron energy loss spectroscopy and a first-principle molecular orbital calculation in the literature, we suggest that the softening effect of Si results from a reduction of ionic bonding strength in sapphire (α-Al2O3 with the substitution of Si for Al.

  11. Electronic properties of the III-VI layer compounds GaS, GaSe and InSe. Part II: Photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Antonangeli, F.; Piacentini, M. (Comitato Nazionale per l' Energia Nucleare, Frascati (Italy). Lab. Nazionali di Frascati); Balzarotti, A. (L' Aquila Univ. (Italy). Ist. di Fisica); Grasso, V.; Girlanda, R. (Messina Univ. (Italy). Ist. di Struttura della Materia); Doni, E. (Pisa Univ. (Italy). Ist. di Fisica)

    1979-05-11

    The valence density of states of the III-VI layer compounds GaS, GaSe and InSe is discussed on the basis of the available ultraviolet photoelectron spectra. A new set of X-ray photoelectron spectra, measured homogeneously on the three compounds, are presented and the experimental features are interpreted on the basis of the valence band density of states, calculated by using the band structures obtained in the first paper of this series with the overlap-reduced tight-binding method. The overall similarity of the experimental spectra agrees with the theoretical findings. The dependence of less bound states on the polarization of the exciting radiation is understood on the basis of the computed energy levels. The fine structure shown by some UPS peaks is interpreted, and some experimental features are shown to depend essentially on the interaction between adjacent layers.

  12. Composition faults in ZnIn/sub 2/S/sub 4/(III) layered crystals and their influence on the anisotropic conductivity of this compound

    Energy Technology Data Exchange (ETDEWEB)

    Anagnostopoulos, A.N.; Manolikas, C.; Papadopoulos, D.; Spyridelis, J. (Aristoteles Univ., Thessaloniki (Greece). First Lab. of Physcis)

    1982-08-16

    The electrical conductivity of ZnIn/sub 2/S/sub 4/(III) measured along the c-axis of this compound and perpendicular to it, is highly anisotropic. This anisotropy itself and its temperature dependence are explained by the existence of composition faults between the layers of ZnIn/sub 2/S/sub 4/(III), which are observed by means of electron microscopy.

  13. Measuring the misfit between seismograms using an optimal transport distance: application to full waveform inversion

    Science.gov (United States)

    Métivier, L.; Brossier, R.; Mérigot, Q.; Oudet, E.; Virieux, J.

    2016-04-01

    Full waveform inversion using the conventional L2 distance to measure the misfit between seismograms is known to suffer from cycle skipping. An alternative strategy is proposed in this study, based on a measure of the misfit computed with an optimal transport distance. This measure allows to account for the lateral coherency of events within the seismograms, instead of considering each seismic trace independently, as is done generally in full waveform inversion. The computation of this optimal transport distance relies on a particular mathematical formulation allowing for the non-conservation of the total energy between seismograms. The numerical solution of the optimal transport problem is performed using proximal splitting techniques. Three synthetic case studies are investigated using this strategy: the Marmousi 2 model, the BP 2004 salt model, and the Chevron 2014 benchmark data. The results emphasize interesting properties of the optimal transport distance. The associated misfit function is less prone to cycle skipping. A workflow is designed to reconstruct accurately the salt structures in the BP 2004 model, starting from an initial model containing no information about these structures. A high-resolution P-wave velocity estimation is built from the Chevron 2014 benchmark data, following a frequency continuation strategy. This estimation explains accurately the data. Using the same workflow, full waveform inversion based on the L2 distance converges towards a local minimum. These results yield encouraging perspectives regarding the use of the optimal transport distance for full waveform inversion: the sensitivity to the accuracy of the initial model is reduced, the reconstruction of complex salt structure is made possible, the method is robust to noise, and the interpretation of seismic data dominated by reflections is enhanced.

  14. X-ray diffraction study of the molecular propolis films deposited from an alcohol solution onto the cleavage surfaces of layered V2VI3 compounds

    Science.gov (United States)

    Drapak, S. I.; Gavrylyuk, S. V.; Kaminskii, V. M.; Kovalyuk, Z. D.

    2008-09-01

    The structures of the molecular propolis films deposited from an alcohol solution on the (0001) cleavage surface of layered bismuth selenide and telluride are studied by X-ray diffraction. Despite the chemical interaction between the semiconductor substrates and the organic-substance components, the molecular structural ordering of the propolis films is shown to be identical to that in the films of this substance on the surface of amorphous glass substrates. The chemical and deformation interaction between the organic substance and the layered V2VI3 compounds is found to result in the formation of an organic-inorganic sandwich nanostructure at a distance of ˜0.3 μm from the layered crystal-propolis film interface.

  15. 氮碳共渗工艺过程中化合物层的形成过程%Compound Layer Formation in Nitrocarburizing Process Procedure

    Institute of Scientific and Technical Information of China (English)

    刘娜; 吴汉香

    2012-01-01

    Nitrocarburizing was carried on to 45 # steel specimens in the RJJ —105 pit type gas nitriding furnace, the nitrocarburizing agents were ammonia and methanol. Combined with the working principle of soft nitriding, the major process parameters such as the supply of ammonia and methanol and nitrocarburizing time were controlled to obtain different thickness on surface compound layer, which is the white light layer. The results showed that when nitrogen potential reached a certain amount at 570℃, the white layer was becoming more and more thickening and the subsurface micro-hardness was enhanced with the extension of nitrocarburizing time, but nitrocarburizing time was aver for four hours or more. The white layer thickness had no obvious change, but the obvious ralio of porosity layer appeared on surface compound layer and the subsurface microhardness was decreasing with the extension of time.%在RJJ - 105井式气体渗氮炉中,对45钢试块进行氮碳共渗,渗剂为氨气和甲醇.结合软氮化的工作原理,通过控制氨气供量、甲醇滴入量和氮碳共渗时间等主要工艺参数,使试块获得不同厚度的表层化合物层,即白亮层.结果表明,在570℃下,当氮势达到一定量以后,随着氮碳共渗时间的延长,白亮层增厚,表层显微硬度增加,但氮碳共渗时间超过4h以上时,随着时间的延长,白亮层厚度无明显变化,但是表面出现明显的疏松,表层显微硬度下降.

  16. Reducing hydrogen permeation in 304 stainless steel by compound layers of Al, Zr and Ti oxides films

    Science.gov (United States)

    Hernández L, R. T.; Cortes S, V.; Granados S, J.; Orozco S, S.

    2017-01-01

    A single and double layer formed by thin films coatings of aluminium oxide, zirconium oxide and titanium oxide were deposited over 304 stainless steel surface by ultrasonic spray pyrolysis technique. The steel samples were conformed for tensile tests. The purpose of these layers is to reduce hydrogen embrittlement effect in steel. An electrochemical cell was used in hydrogen charged, where a low concentration of sulfuric acid is utilized like electrolytic solution. Tension trials show the change the fracture type in samples with or without coating after hydrogen charged. The embrittlement percent factor and SEM micrographs indicate a reduction of hydrogen permeation for coated samples with double layer.

  17. Minority acculturation and peer rejection: Costs of acculturation misfit with peer-group norms.

    Science.gov (United States)

    Celeste, Laura; Meeussen, Loes; Verschueren, Karine; Phalet, Karen

    2016-09-01

    How do minority adolescents' personal acculturation preferences and peer norms of acculturation affect their social inclusion in school? Turkish and Moroccan minority adolescents (N = 681) reported their preferences for heritage culture maintenance, mainstream culture adoption, and their experiences of peer rejection as a key indicator of adjustment problems. Additionally, we aggregated peer acculturation norms of maintenance and adoption within ethnically diverse classrooms (N = 230 in 50 Belgian schools), distinguishing between co-ethnic (Turkish or Moroccan classmates only, N = 681) and cross-ethnic norms (also including N = 1,930 other classmates). Cross-ethnic peer-group norms (of adoption and maintenance) and co-ethnic norms (of maintenance, marginally) predicted minority experiences of peer rejection (controlling for ethnic composition). Moreover, misfit of minorities' own acculturation preferences with both cross-ethnic and co-ethnic peer-group norms was harmful. When cross-ethnic norms stressed adoption, 'integrationist' minority youth - who combined culture adoption with maintenance - experienced most peer rejection. Yet, when co-ethnic peers stressed maintenance, 'assimilationist' minority youth experienced most rejection. In conclusion, acculturation misfit with peer-group norms is a risk factor for minority inclusion in ethnically diverse environments.

  18. Identifying potential misfit items in cognitive process of learning engineering mathematics based on Rasch model

    Science.gov (United States)

    Ataei, Sh; Mahmud, Z.; Khalid, M. N.

    2014-04-01

    The students learning outcomes clarify what students should know and be able to demonstrate after completing their course. So, one of the issues on the process of teaching and learning is how to assess students' learning. This paper describes an application of the dichotomous Rasch measurement model in measuring the cognitive process of engineering students' learning of mathematics. This study provides insights into the perspective of 54 engineering students' cognitive ability in learning Calculus III based on Bloom's Taxonomy on 31 items. The results denote that some of the examination questions are either too difficult or too easy for the majority of the students. This analysis yields FIT statistics which are able to identify if there is data departure from the Rasch theoretical model. The study has identified some potential misfit items based on the measurement of ZSTD where the removal misfit item was accomplished based on the MNSQ outfit of above 1.3 or less than 0.7 logit. Therefore, it is recommended that these items be reviewed or revised to better match the range of students' ability in the respective course.

  19. Structural, elastic, electronic and optical properties of a new layered-ternary Ta{sub 4}SiC{sub 3} compound

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.S. [Department of Physics, Rajshahi University, Rajshahi 6205 (Bangladesh); Islam, A.K.M.A., E-mail: azi46@ru.ac.b [Department of Physics, Rajshahi University, Rajshahi 6205 (Bangladesh)

    2011-01-15

    We propose a new layered-ternary Ta{sub 4}SiC{sub 3} with two different stacking sequences ({alpha}- and {beta}-phases) of the metal atoms along c axis and study their structural stability. The mechanical, electronic and optical properties are then calculated and compared with those of other compounds M{sub 4}AX{sub 3} (M=V, Nb, Ta; A=Al, Si and X=C). The predicted compound in the {alpha}-phase is found to possess higher bulk modulus than these compounds. The independent elastic constants of the two phases are also evaluated and the results discussed. The electronic band structures for {alpha}- and {beta}-Ta{sub 4}SiC{sub 3} show metallic conductivity. Ta 5d electrons are mainly contributing to the total density of states (DOS). We see that the hybridization peak of Ta 5d and C 2p lies lower in energy and the Ta 5d-C 2p bond is stronger than Ta 5d-Si 3p bond. Further an analysis of the different optical properties shows the compound to possess improved behavior compared to similar types of compounds.

  20. Spatial Misfit in Participatory River Basin Management: Effects on Social Learning, a Comparative Analysis of German and French Case Studies

    Directory of Open Access Journals (Sweden)

    Ilke Borowski

    2008-06-01

    Full Text Available With the introduction of river basin management, as prescribed by the European Water Framework Directive (WFD, participatory structures are frequently introduced at the hydrological scale without fully adapting them to the decision-making structure. This results in parallel structures and spatial misfits within the institutional settings of river basin governance systems. By analyzing French and German case studies, we show how social learning (SL is impeded by such misfits. We also demonstrate that river basin-scale institutions or actors that link parallel structures are essential for promoting river basins as management entities, and for encouraging SL between actors at the river basin scale. In the multi-scale, multi-level settings of river basin governance, it is difficult to fully exclude spatial misfits. Thus, it is important to take our insights into account in the current transition of water management from the administrative to the hydrological scale to get the greatest benefit from SL processes.

  1. Investigation of p-side contact layers for II-VI compound semiconductor optical devices fabricated on InP substrates by MBE

    Science.gov (United States)

    Takamatsu, Shingo; Nomura, Ichirou; Shiraishi, Tomohiro; Kishino, Katsumi

    2015-09-01

    N-doped p-type ZnTe and ZnSeTe contact layers were investigated to evaluate which is more suitable for use in II-VI compound semiconductor optical devices on InP substrates. Contact resistances (Rc) between the contact layers and several electrode materials (Pd/Pt/Au, Pd/Au, and Au) were measured by the circular transmission line model (c-TLM) method using p-n diode samples grown on InP substrates by molecular beam epitaxy (MBE). The lowest Rc (6.5×10-5 Ω cm2) was obtained in the case of the ZnTe contact and Pd/Pt/Au electrode combination, which proves that the combination is suitable for obtaining low Rc. Yellow light-emitting diode devices with a ZnTe and ZnSeTe p-contact layer were fabricated by MBE to investigate the effect of different contact layers. The devices were characterized under direct current injections at room temperature. Yellow emission at around 600 nm was observed for each device. Higher emission intensity and lower slope resistance were obtained for the device with the ZnTe contact layer and Pd/Pt/Au electrode compared with other devices. These device performances are ascribed to the low Rc of the ZnTe contact and Pd/Pt/Au electrode combination.

  2. Mechanochemical synthesis of finite particle of layered double hydroxide-acetate intercalation compound: Swelling, thin film and ion exchange

    Science.gov (United States)

    Kuramoto, Kyoko; Intasa-Ard, Soontaree (Grace); Bureekaew, Sareeya; Ogawa, Makoto

    2017-09-01

    Acetate intercalated Mg-Al layered double hydroxide was successfully synthesized by the solid-state reactions between magnesium acetate and aluminum hydroxide as the starting materials using a planetary mil. The acetate intercalated Mg-Al layered double hydroxide prepared by the present solid-state reaction was finite particle and was processed into stable aqueous suspension with variable transparency and viscosity depending on the concentration. By drying the suspension on a substrate under nitrogen atmosphere, thin film (with the thickness of several micrometers) of the acetate intercalated Mg-Al layered double hydroxide with the basal plane oriented parallel to the substrate was obtained. The ion exchange ability of the film, which is as an advantage of the acetate form of layered double hydroxide, was shown by the ion exchange with coumarin-3-carboxylate to give a photoluminescent film. The solid-solid reaction is advantageous for the preparation of layered double hydroxides due to the simple and eco-friendly nature (no solvent) of the operation, lower possibility of carbonate contamination and finite particles of the products.

  3. ATOMIC-FORCE MICROSCOPY IMAGING OF TRANSITION-METAL LAYERED COMPOUNDS - A 2-DIMENSIONAL STICK-SLIP SYSTEM

    NARCIS (Netherlands)

    Kerssemakers, J.W J; de Hosson, J.T.M.

    1995-01-01

    Various layered transition metal dichalcogenides were scanned with an optical-lever atomic force microscope (AFM). The microscopic images indicate the occurrence of strong lateral stick-slip effects. In this letter, two models are presented to describe the observations due to stick-slip, i.e.,

  4. [Two-layer adhesive film Diplen-denta C--a new compound containing polymer base and active component Solcoseryl].

    Science.gov (United States)

    Abakarova, D S

    2007-01-01

    Characteristics of the main components of a new effective long-lasting dosage form--biopolymer two-layer adhesive solcoseryl containing film Diplen-denta C--are presented. It has a potent wound-healing action on oral mucosa, retains therapeutic properties during long time, is self dissolving and can be easily fixed on oral mucous membrane.

  5. ATOMIC-FORCE MICROSCOPY IMAGING OF TRANSITION-METAL LAYERED COMPOUNDS - A 2-DIMENSIONAL STICK-SLIP SYSTEM

    NARCIS (Netherlands)

    Kerssemakers, J.W J; de Hosson, J.T.M.

    1995-01-01

    Various layered transition metal dichalcogenides were scanned with an optical-lever atomic force microscope (AFM). The microscopic images indicate the occurrence of strong lateral stick-slip effects. In this letter, two models are presented to describe the observations due to stick-slip, i.e., eithe

  6. Atomic force microscopy imaging of transition metal layered compounds : A two-dimensional stick–slip system

    NARCIS (Netherlands)

    Kerssemakers, J.; Hosson, J.Th.M. De

    1995-01-01

    Various layered transition metal dichalcogenides were scanned with an optical-lever atomic force microscope (AFM). The microscopic images indicate the occurrence of strong lateral stick–slip effects. In this letter, two models are presented to describe the observations due to stick–slip, i.e., eithe

  7. Highly efficient multilayer organic pure blue light emitting diodes with substituted carbazoles compounds in the emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, A [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Chenais, S [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Forget, S [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Castex, M-C [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Ades, D [Biomateriaux et Polymeres de Specialite (BPS/B2OA, CNRS), Institut Galilee, Universite Paris 13, Villetaneuse/Faculte de Medecine Lariboisiere-St Louis, Universite Paris 7, 75010 Paris (France); Siove, A [Biomateriaux et Polymeres de Specialite (BPS/B2OA, CNRS), Institut Galilee, Universite Paris 13, Villetaneuse/Faculte de Medecine Lariboisiere-St Louis, Universite Paris 7, 75010 Paris (France); Denis, C [Laboratoire Cellules et Composants, CEA/LITEN/DSEN, CEA Saclay, 91191 Gif-sur-Yvette (France); Maisse, P [Laboratoire Cellules et Composants, CEA/LITEN/DSEN, CEA Saclay, 91191 Gif-sur-Yvette (France); Geffroy, B [Laboratoire Cellules et Composants, CEA/LITEN/DSEN, CEA Saclay, 91191 Gif-sur-Yvette (France)

    2006-03-07

    Bright blue organic light-emitting diodes (OLEDs) based on 1, 4, 5, 8, N-pentamethylcarbazole (PMC) and on dimer of N-ethylcarbazole (N, N'-diethyl-3, 3'-bicarbazyl) (DEC) as emitting layers or as dopants in a 4, 4'-bis(2, 2'-diphenylvinyl)-1, 1'-biphenyl (DPVBi) matrix are described. Pure blue light with the CIE coordinates (x = 0.153, y = 0.100), electroluminescence efficiency {eta}{sub EL} of 0.4 cd A{sup -1}, external quantum efficiency {eta}{sub ext} of 0.6% and luminance L of 236 cd m{sup -2} (at 60 mA cm{sup -2}) were obtained with PMC as an emitter and the 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenantroline (BCP) as a hole-blocking material in five-layer emitting devices. The highest efficiencies {eta}{sub EL} of 4.7 cd A{sup -1} and {eta}{sub ext} = 3.3% were obtained with a four-layer structure and a DPVBi DEC-doped active layer (CIE coordinates x = 0.158, y = 0.169, {lambda}{sub peak} = 456 nm). The {eta}{sub ext} value is one the highest reported at this wavelength for blue OLEDs and is related to an internal quantum efficiency up to 20%.

  8. Highly efficient multilayer organic pure blue light emitting diodes with substituted carbazoles compounds in the emitting layer

    Science.gov (United States)

    Fischer, A.; Chénais, S.; Forget, S.; Castex, M.-C.; Adès, D.; Siove, A.; Denis, C.; Maisse, P.; Geffroy, B.

    2006-03-01

    Bright blue organic light-emitting diodes (OLEDs) based on 1, 4, 5, 8, N-pentamethylcarbazole (PMC) and on dimer of N-ethylcarbazole (N, N'-diethyl-3, 3'-bicarbazyl) (DEC) as emitting layers or as dopants in a 4, 4'-bis(2, 2'-diphenylvinyl)-1, 1'-biphenyl (DPVBi) matrix are described. Pure blue light with the CIE coordinates (x = 0.153, y = 0.100), electroluminescence efficiency ηEL of 0.4 cd A-1, external quantum efficiency ηext of 0.6% and luminance L of 236 cd m-2 (at 60 mA cm-2) were obtained with PMC as an emitter and the 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenantroline (BCP) as a hole-blocking material in five-layer emitting devices. The highest efficiencies ηEL of 4.7 cd A-1 and ηext = 3.3% were obtained with a four-layer structure and a DPVBi DEC-doped active layer (CIE coordinates x = 0.158, y = 0.169, λpeak = 456 nm). The ηext value is one the highest reported at this wavelength for blue OLEDs and is related to an internal quantum efficiency up to 20%.

  9. Highly efficient multilayer organic pure-blue-light emitting diodes with substituted carbazoles compounds in the emitting layer

    CERN Document Server

    Fischer, A; Chenais, S; Castex, M C; Siove, A; Ades, D; Geffroy, B; Denis, C; Maisse, P; Fischer, Alexis; Forget, Sebastien; Chenais, Sebastien; Castex, Marie-Claude; Siove, Alain; Ades, Dominique; Geffroy, Bernard; Denis, Christine; Maisse, Pascal

    2006-01-01

    Bright blue organic light-emitting diodes (OLEDs) based on 1,4,5,8,N-pentamethylcarbazole (PMC) and on dimer of N-ethylcarbazole (N,N'-diethyl-3,3'-bicarbazyl) (DEC) as emitting layers or as dopants in a 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi) matrix are described. Pure blue-light with the C.I.E. coordinates x = 0.153 y = 0.100, electroluminescence efficiency \\eta_{EL} of 0.4 cd/A, external quantum efficiency \\eta_{ext.} of 0.6% and luminance L of 236 cd/m2 (at 60 mA/cm2) were obtained with PMC as an emitter and the 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline (BCP) as a hole-blocking material in five-layer emitting devices. The highest efficiencies \\eta_{EL.} of 4.7 cd/A, and \\eta_{ext} = 3.3% were obtained with a four-layer structure and a DPVBi DEC-doped active layer (CIE coordinates x = 0.158, y=0.169, \\lambda_{peak} = 456 nm). The \\eta_{ext.} value is one the highest reported at this wavelength for blue OLEDs and is related to an internal quantum efficiency up to 20%.

  10. The layered compound poly[mu2-4,4'-bipyridyl-di-mu2-chlorido-mercury(II)].

    Science.gov (United States)

    Xie, Yi-Ming; Wu, Ji-Huai

    2007-05-01

    The title compound, [HgCl2(C(10)H(8)N(2))]n, features two-dimensional [HgCl2(4,4'-bipy)]n neutral networks (4,4'-bipy is 4,4'-bipyridine), based on an octahedral Hg atom coordinated by four mu2-Cl atoms and two mu2-4,4'-bipy ligands in trans positions, yielding a HgCl(4)N(2) octahedron. The structure has mmm symmetry about the Hg atoms, with most of the atoms on at least one mirror plane, but the unsubstituted C atoms of the 4,4'-bipy rings are disordered across a mirror plane. Photoluminescent investigations reveal that the title compound displays a strong emission in the green region, which probably originates from a ligand-to-ligand charge-transfer transition.

  11. Crystalline structures and misfit strain inside Er silicide nanocrystals self-assembled on Si(001) substrates.

    Science.gov (United States)

    Ding, Tao; Wu, Yueqin; Song, Junqiang; Li, Juan; Huang, Han; Zou, Jin; Cai, Qun

    2011-06-17

    The morphology and crystalline structure of Er silicide nanocrystals self-assembled on the Si(001) substrate were investigated using scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). It was found that the nanowires and nanorods formed at 630 °C has dominant hexagonal AlB(2)-type structure, while inside the nanoislands self-organized at 800 °C the tetragonal ThSi(2)-type structure is prevalent. The lattice analysis via cross-sectional high-resolution TEM demonstrated that internal misfit strain plays an important role in controlling the growth of nanocrystals. With the relaxation of strain, the nanoislands could evolve from a pyramid-like shape into a truncated-hut-like shape.

  12. Wave equation dispersion inversion using a difference approximation to the dispersion-curve misfit gradient

    KAUST Repository

    Zhang, Zhendong

    2016-07-26

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh wave dispersion curve using a difference approximation to the gradient of the misfit function. We call this wave equation inversion of skeletonized surface waves because the skeletonized dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the multi-dimensional elastic wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Our method can invert for lateral velocity variations and also can mitigate the local minimum problem in full waveform inversion with a reasonable computation cost for simple models. Results with synthetic and field data illustrate the benefits and limitations of this method. © 2016 Elsevier B.V.

  13. Ab initio study of doping effects in the 42214 compounds: A new family of layered iron-based superconductors

    Science.gov (United States)

    Bucci, F.; Sanna, A.; Profeta, G.; Continenza, A.; Gross, E. K. U.

    2017-01-01

    We present a systematic DFT-GGA theoretical characterization of the RE4Fe2As2Te1 -xO4 -yFy family of compounds (conventionally called 42214) as a function of a set of key tuning parameters: rare earth (RE = Pr, Sm, and Gd), Te content, oxygen → fluorine substitutional doping, and external pressure. We focus our discussion on the effect of these parameters on magnetic stability and on the nonmagnetic electronic structure, as most relevant aspects related to the occurrence of superconductivity. To uncover the complexity of the 42214 crystal structure, the electronic analysis is based on an unfolding procedure that allows us to observe the behavior of the hole and electron pockets of the Fermi surface and of the nesting function. We complete the present study with the characterization of a related hypothetical compound having Se substituting for Te. Our results show that this peculiar compound family offers very good opportunities to properly harness material properties; based on our results, we infer that suitably tuning a variety of parameters, as those examined here, improved superconducting properties could be achieved.

  14. Radiation Tolerant Interfaces: Influence of Local Stoichiometry at the Misfit Dislocation on Radiation Damage Resistance of Metal/Oxide Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Shutthanandan, Vaithiyalingam [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Choudhury, Samrat [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos NM 87545 USA; Manandhar, Sandeep [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Kaspar, Tiffany C. [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Wang, Chongmin [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Devaraj, Arun [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville TN 37996 USA; Thevuthasan, Suntharampilli [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Hoagland, Richard G. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos NM 87545 USA; Dholabhai, Pratik P. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos NM 87545 USA; Uberuaga, Blas P. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos NM 87545 USA; Kurtz, Richard J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2017-04-24

    To understand how variations in interface properties such as misfit-dislocation density and local chemistry affect radiation-induced defect absorption and recombination, we have explored a model system of CrxV1-x alloy epitaxial films deposited on MgO single crystals. By controlling film composition, the lattice mismatch with MgO was adjusted so that the misfit-dislocation density varies at the interface. These interfaces were exposed to irradiation and in situ results show that the film with a semi-coherent interface (Cr) withstands irradiation while V film, which has similar semi-coherent interface like Cr, showed the largest damage. Theoretical calculations indicate that, unlike at metal/metal interfaces, the misfit dislocation density does not dominate radiation damage tolerance at metal/oxide interfaces. Rather, the stoichiometry, and the precise location of the misfit-dislocation density relative to the interface, drives defect behavior. Together, these results demonstrate the sensitivity of defect recombination to interfacial chemistry and provide new avenues for engineering radiation-tolerant nanomaterials.

  15. Surface Properties of Fe4N Compounds Layer on AISI 4340 Steel Modified by Pulsed Plasma Nitriding

    Institute of Scientific and Technical Information of China (English)

    J.C.Díaz-Guillén; G.Vargas-Gutiérrez; E.E.Granda-Gutiérrez; J.S.Zamarripa-Pi(n)a; S.I.Pérez-Aguilar; J.Candelas-Ramirez; L.(A)lvarez-Contreras

    2013-01-01

    In this work,the effect of nitriding current density on hardness,crystalline phase composition,layer thickness and corrosion rate of AISI 4340 steel has been studied.X-ray diffraction analysis shows that thin layers formed during nitriding process are constituted of γ-Fe4N for samples processed between 1 and 2.5 mA/cm2.Thickness of nitrided layer increases proportionally to current density (0 μm for 0.5 mA/cm2 to 15 μm for 2.5 mA/cm2).Plasma nitriding increased the surface hardness from 300 HV50g for untreated sample,to around 800HV50g for nitrided samples at 1 mA/cm2.While the untreated samples exhibited a corrosion rate of 0.153 mm per year,the corrosion performance was improved up to 0.03 mm per year at current densities above 1 mA/cm2,which is about one fifth of the corrosion rate of the untreated sample.

  16. Monoclinic 122-Type BaIr2Ge2 with a Channel Framework: A Structural Connection between Clathrate and Layered Compounds

    Directory of Open Access Journals (Sweden)

    Xin Gui

    2017-07-01

    Full Text Available A new 122-type phase, monoclinic BaIr2Ge2 is successfully synthesized by arc melting; X-ray diffraction and scanning electron microscopy are used to purify the phase and determine its crystal structure. BaIr2Ge2 adopts a clathrate-like channel framework structure of the monoclinic BaRh2Si2-type, with space group P21/c. Structural comparisons of clathrate, ThCr2Si2, CaBe2Ge2, and BaRh2Si2 structure types indicate that BaIr2Ge2 can be considered as an intermediate between clathrate and layered compounds. Magnetic measurements show it to be diamagnetic and non-superconducting down to 1.8 K. Different from many layered or clathrate compounds, monoclinic BaIr2Ge2 displays a metallic resistivity. Electronic structure calculations performed for BaIr2Ge2 support its observed structural stability and physical properties.

  17. Characterization of organic-inorganic hybrid layered perovskite and intercalated compound (n-C12H25NH3)2ZnCl4

    Science.gov (United States)

    Abdel-Kader, M. M.; Aboud, A. I.; Gamal, W. M.

    2016-05-01

    We report on some electrical properties and solid-solid phase transitions of organic-inorganic hybrid layered halide perovskite and intercalated compound (n-C12H25NH3)2ZnCl4 which is one member of the long-chain compounds of the series (n-CnH2n+1NH3)2,(n = 8-18). The complex dielectric permittivity ɛ*(ω,T) and the ac conductivity σ (ω,T) were measured as functions of temperature 100 K phase transition at T ≈ (362 ± 2) K, where the compound changes its state from intercalation to non-intercalation with a drastic increase in the c-axis by about 16.4%. The behavior of the frequency-dependent conductivity follows the Jonscher universal power law: σ (ω, T) αῳs(ῳ,T). The mechanism of electrical conduction in the low-temperature phase (phase II) can be described as quantum mechanical tunneling model.

  18. Rapid Identification and Comparison of Compounds with Antioxidant Activity in Coreopsis tinctoria Herbal Tea by High-Performance Thin-Layer Chromatography Coupled with DPPH Bioautography and Densitometry.

    Science.gov (United States)

    Lam, Shing-Chung; Lam, Sio-Fong; Zhao, Jing; Li, Shao-Ping

    2016-09-01

    A simple and efficient method based on high-performance thin-layer chromatography coupled with 2,2-diphenyl-1-picrylhydrazyl (DPPH) bioautography (HPTLC-DPPH) was established for the screening and comparison of antioxidants in different parts of Coreopsis tinctoria herbal tea from different origins and other related herbal tea materials, which used Chrysanthemum morifolium cv. "Gongju" and "Hangju" in this study. Scanning densitometry after DPPH derivatization was applied for the determination of antioxidant capacities of isolated compounds in each sample. It is considered that ethanol extracts of C. tinctoria had stronger antioxidant activity and more characteristic bands than those of 2 compared samples, C. morifolium cv. "Gongju" and "Hangju." Chemometric analysis results showed that the combination of hierarchical clustering analysis and principal component analysis based on determined antioxidant capacities could be used for the discrimination of different parts of C. tinctoria and C. morifolium. Results showed that 7 compounds made up the major contributions of antioxidant activity in C. tinctoria, including okanin, isookanin, marein, flavanomarein, 5,7,3',5'-tetrahydroxyflavanone-7-O-glucoside, 3,5-dicaffeoylquinic acid, and chlorogenic acid. Therefore, 7 compounds were identified as major antioxidant biomarkers for quality control of C. tinctoria. Results demonstrated that the established method could be applied for the identification of C. tinctoria, and were beneficial for the bioactivity-based quality control of C. tinctoria.

  19. A novel Whole Air Sample Profiler (WASP for the quantification of volatile organic compounds in the boundary layer

    Directory of Open Access Journals (Sweden)

    J. E. Mak

    2013-05-01

    Full Text Available The emission and fate of reactive VOCs is of inherent interest to those studying chemical biosphere-atmosphere interactions. In-canopy VOC observations are obtainable using tower-based samplers, but the lack of suitable sampling systems for the full boundary layer has limited the data characterizing the vertical structure of such gases above the canopy height and still in the boundary layer. This is the important region where many reactive VOCs are oxidized or otherwise removed. Here we describe an airborne sampling system designed to collect a vertical profile of air into a 3/8" OD tube 150 m in length. The inlet ram air pressure is used to flow sampled air through the tube, which results in a varying flow rate based on aircraft speed and altitude. Since aircraft velocity decreases during ascent, it is necessary to account for the variable flow rate into the tube. This is accomplished using a reference gas that is pulsed into the air stream so that the precise altitude of the collected air can be reconstructed post-collection. The pulsed injections are also used to determine any significant effect from diffusion/mixing within the sampling tube, either during collection or subsequent extraction for gas analysis. This system has been successfully deployed, and we show some measured vertical profiles of isoprene and its oxidation products methacrolein and methyl vinyl ketone from a mixed canopy near Columbia, Missouri.

  20. A novel Whole Air Sample Profiler (WASP) for the quantification of volatile organic compounds in the boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Mak, J. E.; Su, L.; Guenther, Alex B.; Karl, Thomas G.

    2013-10-16

    The emission and fate of reactive VOCs is of inherent interest to those studying chemical biosphere-atmosphere interactions. In-canopy VOC observations are obtainable using tower-based samplers, but the lack of suitable sampling systems for the full boundary 5 layer has limited the data characterizing the vertical structure of such gases above the canopy height and still in the boundary layer. This is the important region where many reactive VOCs are oxidized or otherwise removed. Here we describe an airborne sampling system designed to collect a vertical profile of air into a 3/800 OD tube 150m in length. The inlet ram air pressure is used to flow sampled air through the 10 tube, which results in a varying flow rate based on aircraft speed and altitude. Since aircraft velocity decreases during ascent, it is necessary to account for the variable flow rate into the tube. This is accomplished using a reference gas that is pulsed into the air stream so that the precise altitude of the collected air can be reconstructed post-collection. The pulsed injections are also used to determine any significant effect 15 from diffusion/mixing within the sampling tube, either during collection or subsequent extraction for gas analysis. This system has been successfully deployed, and we show some measured vertical profiles of isoprene and its oxidation products methacrolein and methyl vinyl ketone from a mixed canopy near Columbia, Missouri.

  1. Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ZrAs1.58 Se0.39

    Science.gov (United States)

    Cichorek, T.; Bochenek, L.; Schmidt, M.; Czulucki, A.; Auffermann, G.; Kniep, R.; Niewa, R.; Steglich, F.; Kirchner, S.

    2016-09-01

    We address the origin of the magnetic-field-independent -|A |T1 /2 term observed in the low-temperature resistivity of several As-based metallic systems of the PbFCl structure type. For the layered compound ZrAs1.58 Se0.39 , we show that vacancies in the square nets of As give rise to the low-temperature transport anomaly over a wide temperature regime of almost two decades in temperature. This low-temperature behavior is in line with the nonmagnetic version of the two-channel Kondo effect, whose origin we ascribe to a dynamic Jahn-Teller effect operating at the vacancy-carrying As layer with a C4 symmetry. The pair-breaking nature of the dynamical defects in the square nets of As explains the low superconducting transition temperature Tc≈0.14 K of ZrAs1.58 Se0.39 compared to the free-of-vacancies homologue ZrP1.54 S0.46 (Tc≈3.7 K ). Our findings should be relevant to a wide class of metals with disordered pnictogen layers.

  2. Trilinear analysis of thin-layer chromatography retention of 35 model compounds chromatographed on nine adsorbents with 20 pure solvents.

    Science.gov (United States)

    Komsta, Łukasz; Skibiński, Robert; Bezpalko, Natalia; Mielniczek, Aleksandra; Stępkowska, Barbara

    2016-11-01

    The RF value dataset of 35 model compounds, chromatographed with 20 pure solvents as the mobile phase each on nine adsorbents: RP2, RP8, RP18, alumina, cellulose, CN, DIOL, NH2 , and silica, was subjected to trilinear analysis with parallel factor analysis. The two-factor optimal model explained 87% of total information in this complex dataset. The first obtained score (trend) represents two features: the presence of hydrogen bonding and heteroatoms of solute and the mean elution force of the solvent. The second trend represents molecule size, aromaticity, and number of carbons, interconnected with presence of chlorine in mobile phase. The correlation between the scores and molecular descriptors were checked to interpret these trends quantitatively. The scores of adsorbents were slightly intercorrelated, showing NH2 , alumina, and cellulose as outliers from main adsorbents cloud. The obtained results suggest that molecular size and aromaticity, connected with chlorine atoms in mobile phase, is the second source of retention variability.

  3. The effect of prolonged heat treatments on the microstructural evolution of Al/Ni intermetallic compounds in multi layered composites

    Energy Technology Data Exchange (ETDEWEB)

    Brunelli, K., E-mail: katya.brunelli@unipd.it [Dipartimento di Ingegneria Industriale, University of Padova, Via Marzolo 9, Padova (Italy); Peruzzo, L. [CNR, Istituto di Geoscienze e Georisorse, Via Gradenigo 6, Padova (Italy); Dabalà, M. [Dipartimento di Ingegneria Industriale, University of Padova, Via Marzolo 9, Padova (Italy)

    2015-01-15

    In this work the effects of prolonged heat treatments on the microstructural and crystallographic evolution of Al–Ni intermetallic compounds were studied in Al/Ni multilayer samples, produced by accumulative roll bonding (ARB) process. Starting from aluminium and nickel sheets, the stacks were composed alternating three aluminium with two nickel sheets. After six rolling passes, the roll-bonded material was heat treated in a tubular furnace at 500, 550 and 600 °C for different times (1–20 h). The ARB process followed by the diffusion heat treatments allowed the formation of four Al–Ni intermetallic phases (Al{sub 3}Ni, Al{sub 3}Ni{sub 2}, AlNi and AlNi{sub 3}). Microstructural analyses of the obtained samples were carried out by scanning electron microscopy (SEM). The electron backscattered diffraction (EBSD) technique was used for the crystallographic analysis of the samples. After the prolonged annealing, three different sequences of phases, starting from Al, were observed: Al{sub 3}Ni{sub 2}–AlNi–AlNi{sub 3}, Al{sub 3}Ni and AlNi–Al{sub 3}Ni. The EBSD analysis showed that the intermetallic phases grew with a mean grain size between 0.5 μm and 3 μm and without a preferential crystallographic orientation. - Highlights: • Study of the prolonged annealing on Al/Ni system. • The presence of AlNi{sub 3} phase, not detected in similar researches, has been observed. • Three different sequences of phases were detected. • From EBSD analysis the intermetallic compounds have no preferred orientation.

  4. Superconductivity at 43 K in an iron-based layered compound LaO(1-x)F(x)FeAs.

    Science.gov (United States)

    Takahashi, Hiroki; Igawa, Kazumi; Arii, Kazunobu; Kamihara, Yoichi; Hirano, Masahiro; Hosono, Hideo

    2008-05-15

    The iron- and nickel-based layered compounds LaOFeP (refs 1, 2) and LaONiP (ref. 3) have recently been reported to exhibit low-temperature superconducting phases with transition temperatures T(c) of 3 and 5 K, respectively. Furthermore, a large increase in the midpoint T(c) of up to approximately 26 K has been realized in the isocrystalline compound LaOFeAs on doping of fluoride ions at the O2- sites (LaO(1-x)F(x)FeAs). Experimental observations and theoretical studies suggest that these transitions are related to a magnetic instability, as is the case for most superconductors based on transition metals. In the copper-based high-temperature superconductors, as well as in LaOFeAs, an increase in T(c) is often observed as a result of carrier doping in the two-dimensional electronic structure through ion substitution in the surrounding insulating layers, suggesting that the application of external pressure should further increase T(c) by enhancing charge transfer between the insulating and conducting layers. The effects of pressure on these iron oxypnictide superconductors may be more prominent than those in the copper-based systems, because the As ion has a greater electronic polarizability, owing to the covalency of the Fe-As chemical bond, and, thus, is more compressible than the divalent O2- ion. Here we report that increasing the pressure causes a steep increase in the onset T(c) of F-doped LaOFeAs, to a maximum of approximately 43 K at approximately 4 GPa. With the exception of the copper-based high-T(c) superconductors, this is the highest T(c) reported to date. The present result, together with the great freedom available in selecting the constituents of isocrystalline materials with the general formula LnOTMPn (Ln, Y or rare-earth metal; TM, transition metal; Pn, group-V, 'pnicogen', element), indicates that the layered iron oxypnictides are promising as a new material platform for further exploration of high-temperature superconductivity.

  5. Comparison of misfit functions for phase-only inversion in the frequency domain

    Science.gov (United States)

    Jeong, G.; Jeong, W.; Min, D. J.

    2014-12-01

    Full waveform inversion suffers from non-uniqueness and non-linearity problems. By using kinematic property of wavefield rather than dynamic property, we can mitigate such problems because the phase is linear and robust (Kamei et al. 2013). For the phase-only inversion, several misfit functions were suggested. Bednar et al. (2007) compared the logarithmic phase-only inversion proposed by Shin and Min (2006) with the conventional phase-only inversion. On the other hand, Kamei et al. (2014) introduced another method that uses the exponential of phase by normalizing the wavefield with respect to the amplitude. In this study, we compare the aforementioned three phase-only inversion methods in the frequency domain: i) the logarithmic phase-only inversion, ii) the conventional phase-only inversion I (briefly conventional I method) that normalizes wavefield with respect to the amplitude variation, and iii) the conventional phase-only inversion II (briefly conventional II method) that replaces the amplitude of the modeled data with that of field data. In the cases of the logarithmic and conventional I methods, if the modeled signal function is close to 0 or becomes large, the gradients of the misfit function diverge to infinity or converge to 0, respectively. In contrast, the conventional II method does not suffer from these problems. For fair comparison, we removed extremely small or large values with Gaussian filtering to avoid the instability problem in the logarithmic and conventional I methods. In addition, we assumed that the phase of the field data is unwrapped to the same degree as the phase of the modeled data in all the cases. On the other hand, the logarithmic and conventional II methods require the additional assumption that amplitudes of the field data are the same as those of the modeled data. However, the conventional I method does not require such an assumption. Our numerical examples show that the conventional I method yields more robust and accurate

  6. Composite glycerol/graphite/aromatic acid matrices for thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry of heterocyclic compounds.

    Science.gov (United States)

    Esparza, Cesar; Borisov, R S; Varlamov, A V; Zaikin, V G

    2016-10-28

    New composite matrices have been suggested for the analysis of mixtures of different synthetic organic compounds (N-containing heterocycles and erectile dysfunction drugs) by thin layer chromatography/matrix-assisted laser desorption ionization time-of-flight mass spectrometry (TLC/MALDI-TOF). Different mixtures of classical MALDI matrices and graphite particles dispersed in glycerol were used for the registration of MALDI mass spectra directly from TLC plates after analytes separation. In most of cases, the mass spectra possessed [M+H](+) ions; however, for some analytes only [M+Na](+) and [M+K](+) ions were observed. These ions have been used to generate visualized TLC chromatograms. The described approach increases the desorption/ionization efficiencies of analytes separated by TLC, prevent spot blurring, simplifies and decrease time for sample preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Swelling and gel/sol formation of perchlorate-type layered double hydroxides in concentrated aqueous solutions of amino acid-related zwitterionic compounds.

    Science.gov (United States)

    Iyi, Nobuo; Ishihara, Shinsuke; Kaneko, Yoshiro; Yamada, Hirohisa

    2013-02-26

    ClO(4)(-)MgAl-LDH3, a MgAl (Mg/Al = 3) layered double hydroxide (LDH) containing perchlorate, swells and forms colloidal suspensions (sols) via the gel state in concentrated aqueous solutions of zwitterionic compounds related to amino acids. In total, 36 zwitterionic compounds with different molecular structures and additional functional groups were examined at various concentrations, and the sol-formation ability was judged by the transmittance (at λ = 589 nm) of the resulting suspensions. At low concentration, the obtained suspensions were turbid, with transmittances of ~0%. However, above the threshold concentration (0.3-1.0 M), osmotic swelling occurred and the transmittances of the suspensions increased sharply with increases in concentration to reach maximum values of 70-95%. The threshold concentration and maximum transmittance value depended on the structure and the location of the functional groups. The enhancement of the permittivity of water by the zwitterions and the formation of H-bond networks were assumed to be the reasons for the swelling phenomenon. Similar gel/sol formation was observed for ClO(4)(-)LDHs with Mg/Al = 2, Ni/Al = 2, 3, and Co/Al = 2 and some NO(3)(-)LDHs. Large ClO(4)(-)LDH films could be prepared by filtration of the colloidal suspensions followed by washing and drying processes.

  8. A novel lithium intercalation compound based on the layered structure of lithium nitridonickelates Li{sub 3-2x}Ni{sub x}N

    Energy Technology Data Exchange (ETDEWEB)

    Ducros, J.B.; Bach, S.; Pereira-Ramos, J.P. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France); Willmann, P. [Centre National d' udes Spatiales, 118 avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2007-08-01

    New lithium nickel nitrides Li{sub 3-2x}Ni{sub x}N (0.20 {<=} x {<=} 0.60) have been prepared and investigated as negative electrode in the 0.85/0.02 V potential window. These materials are prepared from a Ni/Li{sub 3}N mixture at 700 C under a nitrogen flow. Their structural characteristics as well as their electrochemical behaviour are investigated as a function of the nickel content. For the first time are reported here the electrochemical properties of a lithium intercalation compound based on a layered nitride structure. The Li{sub 3-2x}Ni{sub x}N compounds can be reversibly reduced and oxidized around 0.5 V versus Li/Li{sup +} leading to specific capacities in the range 120-160 mAh/g depending on the nickel content and the C rate. Due to a large number of lithium vacancies, the structural stability provides an excellent capacity retention of the specific capacity upon cycling. (author)

  9. A novel lithium intercalation compound based on the layered structure of lithium nitridonickelates Li{sub 3-2x}Ni {sub x}N

    Energy Technology Data Exchange (ETDEWEB)

    Ducros, J.B. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France); Bach, S. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France)]. E-mail: bach@glvt-cnrs.fr; Pereira-Ramos, J.P. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France); Willmann, P. [Centre National d' udes Spatiales, 118 avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2007-08-01

    New lithium nickel nitrides Li{sub 3-2x}Ni {sub x}N (0.20 {<=} x {<=} 0.60) have been prepared and investigated as negative electrode in the 0.85/0.02 V potential window. These materials are prepared from a Ni/Li{sub 3}N mixture at 700 {sup o}C under a nitrogen flow. Their structural characteristics as well as their electrochemical behaviour are investigated as a function of the nickel content. For the first time are reported here the electrochemical properties of a lithium intercalation compound based on a layered nitride structure. The Li{sub 3-2x}Ni {sub x}N compounds can be reversibly reduced and oxidized around 0.5 V versus Li/Li{sup +} leading to specific capacities in the range 120-160 mAh/g depending on the nickel content and the C rate. Due to a large number of lithium vacancies, the structural stability provides an excellent capacity retention of the specific capacity upon cycling.

  10. Synthesis and antibacterial activity of new layered perovskite compounds, AgxNa2-xLa2Ti3O10

    Institute of Scientific and Technical Information of China (English)

    Shao Zao Tan; Liu Cai Ding; Ying Liang Liu; You Sheng Ouyang; Yi Ben Chen

    2007-01-01

    Three kinds of new layered perovskite compounds with Ruddlesden-Popper (R-P) phase, AgxNa2-xLa2Ti3O10 (x = 0.2, 0.3 and 0.5), were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution. The structures of the compounds were characterized by EDX and XRD, and their antibacterial activity and light-resistance property were evaluated. The results indicated that the molecular formula of AgxNa2-xLa2Ti3O10 (x = 0.2, 0.3 and 0.5) was confirmed, and that the crystalline structure of Na2La2Ti3O10 was not obviously affected by exchange of silver ion. The minimum inhibitory concentrations (MICs) of Ag0.3Na1.7La2Ti3O10 against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) were 180 μg/mL and 240 μg/mL,respectively, while its discoloration was not observed after 24 h light ageing test.

  11. Electronic properties of the III-VI layer compounds GaS, GaSe and InSe. Part I: Band structure

    Energy Technology Data Exchange (ETDEWEB)

    Doni, E. (Pisa Univ. (Italy). Ist. di Fisica); Girlanda, R.; Grasso, V. (Messina Univ. (Italy). Ist. di Struttura della Materia); Balzarotti, A. (L' Aquila Univ. (Italy). Ist. di Fisica); Piacentini, M. (Comitato Nazionale per l' Energia Nucleare, Frascati (Italy). Lab. Nazionali di Frascati)

    1979-05-11

    The electronic properties of the semiconducting layer compounds GaS, GaSe and InSe are considered comparatively in a series of papers. In this first paper the band structures of the three compounds are computed by using the same method and the same approximations for all of them. The overlap-reduced semi-empirical tight-binding method (ORSTB) is outlined at first. The method consists in scaling only the overlap integrals in the secular equation. In this way it takes into account the localization of the atomiclike functions used in the Bloch sums in a more effective and simpler way than previous tight-binding semi-empirical schemes. For GaS, GaSe and InSe bands only two scaling factors are used as matching parameters to reproduce optical and photo-emission experimental data. The agreement between computed and experimental bands is very good. In particular, the shape of the bonding metal-metal bands which all previous tight-binding calculations failed a dipolar moment. The SEP is the macroscopic results of the alignment and the ''freezing-in'' of those structures. The study of the SEP promises to be useful in understanding the kinetic of the vapour-solid phase transition and in acquiring information about the structural transformations and phase transitions of the solids.

  12. A new potential NLO compound with a supramolecular layered structure: aqua(hexamethylenetetramine-κN)(iminodiacetato-κ3O,N,O')copper(II).

    Science.gov (United States)

    He, Jiao-Jiao; Chai, Wen-Xiang; Song, Li; Niu, Feng; Fang, Xiao-Bin

    2012-08-01

    In the noncentrosymmetric title compound, [Cu(C(4)H(5)NO(4))(C(6)H(12)N(4))(H(2)O)] or [Cu(IDA)(HMTA)(H(2)O)], where IDA is iminodiacetate and HMTA is hexamethylenetetramine, the asymmetric unit consists of a whole mononuclear neutral molecule, where the Cu(II) cation is coordinated by two carboxylate O atoms and one N atom from the IDA ligand, by one N atom from the HMTA ligand and by the O atom of the coordinated water molecule, giving rise to a CuN(2)O(3) distorted square-pyramidal coordination geometry. The IDA and HTMA ligands adopt terminal tri- and monocoordinated modes, respectively. All adjacent molecules within the ac plane are connected to each other via two pairs of O-H···O and one N-H...O hydrogen bond, forming a (4,4) supramolecular two-dimensional network. In the unit cell, these layers stack alternately in an …ABABAB… sequence along the b axis. The optical absorption properties of this compound have been studied on powder samples, which had previously been examined by powder X-ray diffraction.

  13. The Relationship Between Atomic Structure and Strain Distribution of Misfit Dislocation Cores at Cubic Heteroepitaxial Interfaces.

    Science.gov (United States)

    Wen, Cai

    2017-03-09

    The atomic reconstruction of a misfit dislocation (MD) core causes change in the strain distribution around the core. Several MD cores at the AlSb/GaAs (001) cubic zincblende interface, including a symmetrical glide set Lomer dislocation (LD), a left-displaced glide set LD, a glide set LD with an atomic step, a symmetrical shuffle set LD, and a 60° dislocation pair, were studied using simulated projected potential and aberration-corrected transmission electron microscope images. Image deconvolution was also used to restore structure images from nonoptimum-defocus images. The corresponding biaxial strain maps, ε xx (in-plane) and ε yy (out-of-plane), were obtained by geometric phase analysis using the GaAs substrate as the reference lattice. The results show that atomic structure characteristics of MD cores can be revealed by the strain maps. The strain maps should be measured from optimum-defocus images or restored structure images. Furthermore, the ε xx strain map has been found more accurate than the ε yy strain map for MD cores, and the specimen thickness should be below the critical thickness due to the influence of dynamical scattering.

  14. Revealing dynamics and consequences of fit and misfit between formal and informal networks in multi-institutional product development collaborations

    DEFF Research Database (Denmark)

    Kratzer, Jan; Gemünden, Hans Georg; Lettl, Christopher

    2008-01-01

    The study presents a longitudinal examination about dynamics and consequences of fit and misfit between formally ascribed design interfaces and informal communication networks in two large multi-institutional product development collaborations in space industry. Findings: (1) formally ascribed...... design interfaces and informal communication networks correlate only marginally. The main reason is that informal communication is much more dense than ascribed; (2) although the formally ascribed design interfaces change, the structure of informal communication remains largely stable throughout time; (3...

  15. Revealing dynamics and consequences of fit and misfit between formal and informal networks in multi-institutional product development collaborations

    DEFF Research Database (Denmark)

    Kratzer, Jan; Gemünden, Hans Georg; Lettl, Christopher

    2008-01-01

    The study presents a longitudinal examination about dynamics and consequences of fit and misfit between formally ascribed design interfaces and informal communication networks in two large multi-institutional product development collaborations in space industry. Findings: (1) formally ascribed...... design interfaces and informal communication networks correlate only marginally. The main reason is that informal communication is much more dense than ascribed; (2) although the formally ascribed design interfaces change, the structure of informal communication remains largely stable throughout time; (3...

  16. DIFFUSION-INDUCED STRESS IN THE INTERMETALLIC COMPOUND LAYER OF SOLDER JOINTS%焊锡接点IMC层的扩散应力

    Institute of Scientific and Technical Information of China (English)

    秦飞; 安彤; 夏国峰

    2012-01-01

    钎焊过程中在焊锡接点中形成的金属间化合物(IMC)对焊锡接点可靠性具有重要影响.在原子扩散效应下,回流焊和等温时效过程中IMC层的生长会在其内部产生应力,其微结构也发生变化,致使IMC层和整个焊锡接点的力学性能下降.论文基于扩散反应机制,研究了由于原子扩散产生的IMC层的扩散应力.首先建立了描述焊锡接点IMC层生长早期微结构特征的2界面(Cu/Cu6 Sn5/Solder)分析模型,然后运用Laplace变换法求解扩散方程得到了Cu原了在IMC层中的浓度分布;采用把原子扩散作用转换为体应变方法,计算了IMC层在形成和生长过程中应力的解析解.结果表明:IMC层中的扩散应力为压应力,最大值位于Cu/IMC界面处,大小与扩散原子浓度密切相关;随着时效时间的增加,扩散应力增大,但最终趋于稳定并沿IMC厚度方向线性变化.%Intermetallic compound (IMC) layers formed during soldering processes significantly affect the reliability of solder joints. The atomic diffusion effect during reflow and isothermal aging leads to growth and morphological evolution of IMC layers.and stress is developed in the IMC layers. The changed microstructure and the stress in the IMC layer result in degradation of mechanical performance of solder joints. Based on the mechanism of atomic diffusion-reaction, the diffusion induced stress during the growth of the IMC layer is investigated. An analytic model with two interfaces(Cu/Cu6Sn3/Solder)at the early stages of IMC formation is proposed,and then the copper concentration distribution in the IMC layer is calculated using the Laplace transformation method. Diffusion-induced stresses are obtained analytically by transforming atomic diffusion effects into bulk strain. The results show that the diffusion-induced stress is compressive,and it reaches its peak at the Cu/Cu6Sn5 interface. The diffusion induced stress increases with the increase of the isothermal

  17. Polytypism in LaOBi S2 -type compounds based on different three-dimensional stacking sequences of two-dimensional Bi S2 layers

    Science.gov (United States)

    Liu, Qihang; Zhang, Xiuwen; Zunger, Alex

    2016-05-01

    LaOBi S2 -type materials have drawn much attention recently because of various interesting physical properties, such as low-temperature superconductivity, hidden spin polarization, and electrically tunable Dirac cones. However, it was generally assumed that each LaOBi S2 -type compound has a unique and specific crystallographic structure (with a space group P 4 /nmm) separated from other phases. Using first-principles total energy and stability calculations we confirm that the previous assignment of the P 4 /nmm structure to LaOBi S2 is incorrect. Furthermore, we find that the unstable structure is replaced by a family of energetically closely spaced modifications (polytypes) differing by the layer sequences and orientations. We find that the local Bi-S distortion leads to three polytypes of LaOBi S2 with different stacking patterns of the distorted Bi S2 layers. The energy difference between the polytypes of LaOBi S2 is merely ˜1 meV/u.c., indicating the possible coexistence of all polytypes in the real sample and that the particular distribution of polytypes may be growth induced. The in-plane distortion can be suppressed by pressure, leading to a phase transition from polytypes to the high-symmetry P 4 /nmm structure with a pressure larger than 2.5 GPa. In addition, different choices of the intermediate atoms (replacing La) or active atoms (Bi S2 ) could also manifest different ground-state structures. One can thus tune the distortion and the ground state by pressure or by substituting covalence atoms in the LaOBi S2 family.

  18. Number of CuO{sub 2} layers dependence of magnetic quantum criticality in homogeneously doped high-T{sub c} copper oxides: A {sup 63}Cu-NMR study on four-layered high-T{sub c} compounds HgBa{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8+y}

    Energy Technology Data Exchange (ETDEWEB)

    Itohara, Keita, E-mail: itohara@nmr.mp.es.osaka-u.ac.j [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Shimizu, Sunao; Mukuda, Hidekazu; Kitaoka, Yoshio [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Shirage, Parasharam M.; Kito, Hijiri; Iyo, Akira [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)

    2010-12-15

    We report {sup 63}Cu-NMR/NQR studies on Hg-based four-layered compounds HgBa{sub 2}Ca{sub 3}Cu{sub 4} O{sub 8+y} (Hg-1234) with T{sub c}=123, 110, and 95 K. The {sup 63}Cu Knight shift measurements have revealed that the carrier density (N{sub h}) monotonously decreases with decreasing T{sub c}. Although static magnetic order was not observed at N{sub h}=0.15 for the IP with T{sub c}=95K, it was revealed that antiferromagnetic correlations critically develop, preventing from observing the NMR spectrum below {approx}200 K far above T{sub c}. Thus, we deduce that a magnetic quantum critical point, where an AFM order collapses, may exist at slightly less than N{sub h{approx}}0.15 in the Hg-based four-layered compounds, which is lower than that in Hg-based five-layered compounds, N{sub h{approx}}0.17. This result suggests that a magnetic interlayer coupling, which stabilizes an AFM order, becomes weaker in the four-layered compounds than in five-layered compounds.

  19. Cu2+ in layered compounds: origin of the compressed geometry in the model system K2ZnF4:Cu2+.

    Science.gov (United States)

    Aramburu, J A; García-Lastra, J M; García-Fernández, P; Barriuso, M T; Moreno, M

    2013-06-17

    results underline the key role played by ab initio calculations for unveiling all the complexity behind the properties of the model system K2ZnF4:Cu(2+), opening at the same time a window for improving our knowledge on d(9), d(7), or d(4) ions in other layered compounds.

  20. Comparison and Characterization of Compounds with Antioxidant Activity in Lycium barbarum Using High-Performance Thin Layer Chromatography Coupled with DPPH Bioautography and Tandem Mass Spectrometry.

    Science.gov (United States)

    Lam, Shing-Chung; Luo, Zhen; Wu, Ding-Tao; Cheong, Kit-Leong; Hu, De-Jun; Xia, Zu-Meng; Zhao, Jing; Li, Shao-Ping

    2016-06-01

    Methanol extracts from 50 batches of Lycium barbarum (L. barbarum, wolfberry) in China were compared and characterized using high-performance thin-layer chromatography coupled with 2,2-diphenyl-1-picrylhydrazyl (DPPH) bioautography (HPTLC-DPPH) and electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS), respectively. Results showed that similar components occupying the major antioxidant activity existed in L. barbarum collected from different origins. However, the average antioxidant capacities of methanol extracts of L. barbarum collected in Ningxia were significantly higher than those of Qinghai, Xinjiang, Inner Mongolia, and Gansu, which may contribute to rational use of L. barbarum in China. Furthermore, the chemical structure of compound with the highest antioxidant capacity was tentatively identified as 2-O-β-d-glucopyranosyl-l-ascorbic acid using ESI-Q-TOF-MS/MS analysis, which possessed high potentials to be used as an antioxidant biomarker for the quality control of L. barbarum. Results are helpful for the bioactivity-based quality control of L. barbarum, and beneficial for the improvement of their performance in functional/health foods area, suggesting that HPTLC-DPPH bioautography with ESI-Q-TOF-MS/MS could be used as a routine approach for quality control of antioxidant components in L. barbarum. © 2016 Institute of Food Technologists®

  1. (CH3 NH3 )2 PdCl4 : A Compound with Two-Dimensional Organic-Inorganic Layered Perovskite Structure.

    Science.gov (United States)

    Huang, Tang Jiao; Thiang, Zhang Xian; Yin, Xuesong; Tang, Chunhua; Qi, Guojun; Gong, Hao

    2016-02-01

    The synthesis of previously unknown perovskite (CH3 NH3 )2 PdCl4 is reported. Despite using an organic cation with the smallest possible alkyl group, a 2D organic-inorganic layered Pd-based perovskites was still formed. This demonstrates that Pd-based 2D perovskites can be obtained even if the size of the organic cation is below the size limit predicted by the Goldschmidt tolerance-factor formula. The (CH3 NH3 )2 PdCl4 phase has a bulk resistivity of 1.4 Ω cm, a direct optical gap of 2.22 eV, and an absorption coefficient on the order of 10(4)  cm(-1) . XRD measurements suggest that the compound is moderately stable in air, an important advantage over several existing organic-inorganic perovskites that are prone to phase degradation problems when exposed to the atmosphere. Given the recent interest in organic-inorganic perovskites, the synthesis of this new Pd-based organic-inorganic perovskite may be helpful in the preparation and understanding of other organic-inorganic perovskites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Y0.76Ho0.24FeGe2O7: a new member of thortveitite-like layered compounds

    Directory of Open Access Journals (Sweden)

    Ivonne Rosales

    2009-07-01

    Full Text Available Y0.76Ho0.24FeGe2O7 (yttrium holmium iron digermanate was synthesized by solid-state reaction at 1573 K. This thortveitite-like compound presents a crystallographic group–subgroup isotranslational (klassengleiche relation with some other pyrogermanates, such as FeInGe2O7, In1.08Gd0.92Ge2O7 and InYGe2O7, which are configurationally isotypic with the Sc2Si2O7 thortveitite structure first reported by Zachariasen [(1930. Z. Kristallogr. 73, 1–6]. Holmium cations share with yttrium the 4f Wyckoff position at the center of a seven-coordinated pentagonal bipyramid, while Fe atoms also occupy one site with Wyckoff position 4f at the center of the octahedron. All these sites have the point symmetry C1. Two types of Ge2O7 diorthogroups with point symmetry C1h are present in the structure, each one of them defining a layer type which alternates with the other. These diorthogroups have their tetrahedral groups in an eclipsed conformation.

  3. Non-uniform, axisymmetric misfit strain: in thin films bonded on plate substrates/substrate systems: the relation between non-uniform film stresses and system curvatures

    Institute of Scientific and Technical Information of China (English)

    Yonggang Huang; D. Ngo; A.J. Rosakis

    2005-01-01

    Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. By considering a circular thin film/substrate system subject to non-uniform, but axisymmetric misfit strain distributions in the thin film, we derived relations between the film stresses and the misfit strain, and between the plate system's curvatures and the misfit strain. These relations feature a "local"part which involves a direct dependence of the stress or curvature components on the misfit strain at the same point, and a "non-local" part which reflects the effect of misfit strain of other points on the location of scrutiny. Most notably, we also derived relations between the polar components of the film stress and those of system curvatures which allow for the experimental inference of such stresses from full-field curvature measurements in the presence of arbitrary radial non-uniformities. These relations also feature a "non-local"dependence on curvatures making a full-field measurement a necessity. Finally, it is shown that the interfacial shear tractions between the film and the substrate are proportional to the radial gradients of the first curvature invariant and can also be inferred experimentally.

  4. High-performance Thin-layer Chromatography Method Development, Validation, and Simultaneous Quantification of Four Compounds Identified in Standardized Extracts of Orthosiphon stamineus.

    Science.gov (United States)

    Hashim, Suzana; Beh, Hooi Kheng; Hamil, Mohamad Shahrul Ridzuan; Ismail, Zhari; Majid, Amin Malik Shah Abdul

    2016-01-01

    Orthosiphon stamineus is a medicinal herb widely grown in Southeast Asia and tropical countries. It has been used traditionally as a diuretic, abdominal pain, kidney and bladder inflammation, gout, and hypertension. This study aims to develop and validate the high-performance thin layer chromatography (HPTLC) method for quantification of rosmarinic acid (RA), 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (TMF), sinensitin (SIN) and eupatorin (EUP) found in ethanol, 50% ethanol and water extract of O. stamineus leaves. HPTLC method was conducted using an HPTLC system with a developed mobile phase system of toluene: ethyl acetate: formic acid (3:7:0.1) performed on precoated silica gel 60 F254 TLC plates. The method was validated based on linearity, accuracy, precision, limit of detection, limit of quantification (LOQ), and specificity, respectively. The detection of spots was observed at ultraviolet 254 nm and 366 nm. The linearity of RA, TMF, SIN, and EUP were obtained between 10 and 100 ng/spot with high correlation coefficient value (R(2)) of more than 0.986. The limit of detection was found to be 122.47 ± 3.95 (RA), 43.38 ± 0.79 (SIN), 17.26 ± 1.16 (TMF), and 46.80 ± 1.33 ng/spot (EUP), respectively. Whereas the LOQ was found to be 376.44 ± 6.70 (RA), 131.45 ± 2.39 (SIN), 52.30 ± 2.01 (TMF), and 141.82 ± 1.58 ng/spot (EUP), respectively. The proposed method showed good linearity, precision, accuracy, and high sensitivity. Hence, it may be applied in a routine quantification of RA, SIN, TMF, and EUP found in ethanol, 50% of ethanol and water extract of O. stamineus leaves. HPTLC method provides rapid estimation of the marker compound for routine quality control analysis.The established HPTLC method is rapid for qualitative and quantitative fingerprinting of Orthosiphon stamineus extract used for commercial product.Four identified markers (RA, SIN, EUP and TMF) found in three a different type of O. stamineus extracts specifically ethanol, 50% ethanol and water

  5. Instability of a quasi-magnetic structure in a layer compound, Cs{sub 0.5}Rb{sub 0.5}VF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hidaka, M.; Yoshimura, M. [Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Akiyama, H. [Department of Physics, Faculty of Education, Miyazaki University, Miyazaki 889-21 (Japan); Watanabe, S.; Yoshizawa, H. [Neutron scattering Laboratory, ISSP, University of Tokyo, Tokai, Ibaraki 319-1106 (Japan); Wanklyn, B.M. [Claredon Laboratory, Oxford University, Oxford OX1 3PU (United Kingdom)

    2002-07-01

    Magnetic properties of Cs{sub 0.5}Rb{sub 0.5}VF{sub 4} are studied by neutron diffraction. The layer compound shows an antiferromagnetic phase transition at about 34 K (T{sub N}). Its normal antiferromagnetic unit cell is 2a{sub p} x 2b{sub p} x 2c{sub p}, where a{sub p} x a{sub p} x c{sub p} is an ideal unit cell of TlAlF{sub 4}-type. It is found that a quasi-antiferromagnetic phase having a unit cell of 2a{sub p} x 2a{sub p} x c{sub p} is easily induced under a suitable applied field after doing a field cooling of 3 T from 50 K to 2.5 K. The quasi-magnetic structure shows a relaxation dependent on the field strength and the temperature. In the relaxation process, it is found that there is a coexistence of the normal and quasi-antiferromagnetic phases and that the two magnetic phases show a good compensation for a population ratio between two phases made in a used crystal. A metastable magnetic phase transition between the normal and quasi-magnetic phases occurs at about 13 K (T{sub M}). It is also found that only the quasi-magnetic phase shows a critical behavior in the vicinity of the antiferromagnetic phase transition (T{sub N}). It is interpreted that the residual normal antiferromagnetic phases below T{sub M} are made by local structural modulations, which mainly result from an inhomogeneous substitution of Cs with Rb ions in the crystal. (orig.)

  6. "Generality of mis-fit"? The real-life difficulty of matching scales in an interconnected world.

    Science.gov (United States)

    Keskitalo, E Carina H; Horstkotte, Tim; Kivinen, Sonja; Forbes, Bruce; Käyhkö, Jukka

    2016-10-01

    A clear understanding of processes at multiple scales and levels is of special significance when conceiving strategies for human-environment interactions. However, understanding and application of the scale concept often differ between administrative-political and ecological disciplines. These mirror major differences in potential solutions whether and how scales can, at all, be made congruent. As a result, opportunities of seeking "goodness-of-fit" between different concepts of governance should perhaps be reconsidered in the light of a potential "generality of mis-fit." This article reviews the interdisciplinary considerations inherent in the concept of scale in its ecological, as well as administrative-political, significance and argues that issues of how to manage "mis-fit" should be awarded more emphasis in social-ecological research and management practices. These considerations are exemplified by the case of reindeer husbandry in Fennoscandia. Whilst an indigenous small-scale practice, reindeer husbandry involves multi-level ecological and administrative-political complexities-complexities that we argue may arise in any multi-level system.

  7. Structure of misfit dislocations in niobium-sapphire interfaces and strength of interfacial bonding: An atomistic study

    Energy Technology Data Exchange (ETDEWEB)

    Levay, A.; Moebus, G.; Vitek, V.; Ruehle, M.; Tichy, G.

    1999-11-12

    The formation of networks of misfit dislocations is investigated at the (0001){sub Al{sub 2}O{sub 3}}{parallel}(111){sub Nb} interface using a recently proposed approach which employs a very simple pair-potential to describe interaction between the metal and the substrate that contains the strength of interfacial adhesion as a parameter. The calculations demonstrate how the strength of bonding between the two materials decides both the form of the network and the atomic structure of the cores of these dislocations. At the same time it reveals that diffusion is essential for the formation of the observed triangular network of 1/2{l{underscore}angle}111{r{underscore}angle} dislocations. The calculated structures are then used to investigate related high resolution electron microscope (HREM) images using a multislice technique. In these simulations translational symmetry along the electron beam was not assumed but for each slice of material along the beam different sub-structures were used. This allowed us to investigate fully the effect of the dislocation intersections upon the images of the dislocation cores. Their effect is, indeed, considerable if an intersection is in the region producing the image but if not, the images of the cores of misfit dislocations are affected only marginally and HREM can capture fine details of the core structure. A direct comparison of an experimental observation in Mayer and co-workers with the present simulations demonstrates this ability.

  8. Layered perovskite-related ruthenium oxychlorides: crystal structure of two new compounds Ba 5Ru 2Cl 2O 9 and Ba 6Ru 3Cl 2O 12

    Science.gov (United States)

    Tancret, N.; Roussel, P.; Abraham, F.

    2004-03-01

    Single crystals of the title compounds were prepared using a BaCl 2 flux and investigated by X-ray diffraction methods using Mo Kα radiation and a charge coupled device (CCD) detector. The crystal structures of these two new compounds were solved and refined in the hexagonal symmetry with space group P6 3/ mmc, a=5.851(1) Å, c=25.009(5) Å, ρcal=4.94 g cm -3, Z=2 to a final R1=0.069 for 20 parameters with 312 reflections for Ba 5Ru 2Cl 2O 9 and space group P 3¯m1 , a=5.815(1) Å, c=14.915(3) Å, ρcal=5.28 g cm -3, Z=1 to a final R1=0.039 for 24 parameters with 300 reflections for Ba 6Ru 3Cl 2O 12. The structure of Ba 5Ru 2Cl 2O 9 is formed by the periodic stacking along [001] of three hexagonal close-packed BaO 3 layers separated by a double layer of composition Ba 2Cl 2. The BaO 3 stacking creates binuclear face-sharing octahedra units Ru 2O 9 containing Ru(V). The structure of Ba 6Ru 3Cl 2O 12 is built up by the periodic stacking along [001] of four hexagonal close-packed BaO 3 layers separated by a double layer of composition Ba 2Cl 2. The ruthenium ions with a mean oxidation degree +4.67 occupy the octahedral interstices formed by the four layers hexagonal perovskite slab and then constitute isolated trinuclear Ru 3O 12 units. These two new oxychlorides belong to the family of compounds formulated as [Ba 2Cl 2][Ba n+1 Ru nO 3 n+3 ], where n represents the thickness of the octahedral string in hexagonal perovskite slabs.

  9. In situ synthesis and study of morphology and thermal properties of polyamide 6 nanocomposites reinforced with different layered compounds; Sintese in situ e estudo da morfologia e propriedades termicas de nanocompositos de poliamida 6 reforcados com diferentes compostos lamelares

    Energy Technology Data Exchange (ETDEWEB)

    Botan, Rodrigo; Sartor, Sabrina de B.; Moraes, Samara B. de; Lona, Liliane M.F., E-mail: botan.03@gmail.com [Universidade Estadual de Campinas (FEQ/UNICAMP), Campinas, SP (Brazil). Faculdade de Engenharia Quimica

    2013-07-01

    Presently the research and development of new polymer nanocomposites is a field of large interest and importance to the scientific and technological community. For the development and improvement in synthesis and properties of new nanocomposites, different reinforcement types have been explored. Thus, this work studies the in situ synthesis and, morphological and thermal characterization of new polyamide 6 (PA6) nanocomposites reinforced with two different types of layered compounds: layered double hydroxide (LDH) and layered hydroxide salt (LHS). These new synthesized nanocomposites were characterized by x-ray diffraction (XRD), infrared spectroscopy by Fourier transform (FTIR) and thermogravimetric analysis (TGA). The results demonstrate that the new nanocomposites showed strong evidence of exfoliated morphology with improvement in their thermal properties compared with the neat PA6. (author)

  10. Misfit dislocation free InAs/GaSb core-shell nanowires grown by molecular beam epitaxy.

    Science.gov (United States)

    Rieger, T; Grützmacher, D; Lepsa, M I

    2015-01-07

    In this report, we present the growth and structural analyses of broken gap InAs/GaSb core-shell nanowires by molecular beam epitaxy using an Au-free approach. Depending on the shell growth temperature, two distinct growth regimes for the GaSb shells are identified resulting in conformal or tapered shells. Morphological analyses reveal a dodecagonal nanowire cross-section after GaSb shell growth. Detailed transmission electron microscope investigations from different zone axes confirm that the small lattice mismatch of 0.6% allows the deposition of 40 nm thick GaSb shells free of misfit dislocations. Additionally, an abrupt interface from InAs to GaSb is found. These nanowires are suitable for future devices such as TFETs.

  11. Measurements of γ/γ' Lattice Misfit and γ' Volume Fraction for a Ru-containing Nickel-based Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    X.P. Tan; J.L. Liu; X P Song; T. Jin; X.F. Sun; Z.Q. Hu

    2011-01-01

    A conventional X-ray difFractometer has been used to determine the -y/y' lattice misfit and γ' volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature. The rocking curve was used to characterize the distribution of subgrains. The diffraction peaks obtained by w-20 scan were used to determine the γ/γ' lattice misfit and γ' volume fraction. A three peaks fitting model was proposed. The peak fitting results are in good agreement with the model. The X-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material, which is comprised of many subgrains; and each subgrain also consists of large numbers of mosaic structures. In addition, two anomalous reflection phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement. The experimental results show that the γ/γ' lattice misfit and ~/r volume fraction will be various at the different regions of its dendritic microstructure. The average γ/γ' lattice misfit and γ' volume fraction of the experimental alloy are approximately-0.2% and 70%, respectively. Furthermore, the γ' volume fraction calculated by atom microprobe (AP) data is also basically consistent with the experimental results.

  12. Dielectric tunability of vertically aligned ferroelectric-metal oxide nanocomposite films controlled by out-of-plane misfit strain

    Science.gov (United States)

    Wu, Huaping; Ma, Xuefu; Zhang, Zheng; Zhu, Jun; Wang, Jie; Chai, Guozhong

    2016-04-01

    A nonlinear thermodynamic model based on the vertically aligned nanocomposite (VAN) thin films of ferroelectric-metal oxide system has been developed to investigate the physical properties of the epitaxial Ba0.6Sr0.4TiO3 (BST) films containing vertical Sm2O3 (SmO) nanopillar arrays on the SrTiO3 substrate. The phase diagrams of out-of-plane lattice mismatch vs. volume fraction of SmO are calculated by minimizing the total free energy. It is found that the phase transformation and dielectric response of BST-SmO VAN systems are extremely dependent on the in-plane misfit strain, the out-of-plane lattice mismatch, the volume fraction of SmO phase, and the external electric field applied to the nanocomposite films at room temperature. In particular, the BST-SmO VAN systems exhibit higher dielectric properties than pure BST films. Giant dielectric response and maximum tunability are obtained near the lattice mismatch where the phase transition occurs. Under the in-plane misfit strain of umf=0.3 % and the out-of-plane lattice mismatch of u3=0.002 , the dielectric tunability can be dramatically enhanced to 90% with the increase of SmO volume fraction, which is well consistent with previous experimental results. This work represents an approach to further understand the dependence of physical properties on the lattice mismatch (in-plane and out-of-plane) and volume fraction, and to manipulate or optimize functionalities in the nanocomposite oxide thin films.

  13. Interfacial Characterizations of a Nickel-Phosphorus Layer Electrolessly Deposited on a Silane Compound-Modified Silicon Wafer Under Thermal Annealing

    Science.gov (United States)

    Lai, Kuei-Chang; Wu, Pei-Yu; Chen, Chih-Ming; Wei, Tzu-Chien; Wu, Chung-Han; Feng, Shien-Ping

    2016-10-01

    Front-side metallization of a Si wafer was carried out using electroless deposition of nickel-phosphorus (Ni-P) catalyzed by polyvinylpyrrolidone-capped palladium nanoclusters (PVP-nPd). A 3-[2-(2-Aminoethylamino)ethylamino] propyl-trimethoxysilane (ETAS) layer was covalently bonded on the Si surface as bridge linker to the Pd cores of PVP-nPd clusters for improving adhesion between the Ni-P layer and the Si surface. To investigate the effects of an interfacial ETAS layer on the Ni silicide formation at the Ni-P/Si contact, the Ni-P-coated Si samples were thermally annealed via rapid thermal annealing (RTA) from 500°C to 900°C for 2 min. To compare with the ETAS sample, the sputtered Ni layer on Si and electroless Ni-P layer on ion-Pd-catalyzed Si (both are standard processes) were also investigated. The microstructural characterizations for the Ni-P or Ni layer deposited on the Si wafer were performed using x-ray diffractometer, scanning electron microscopy, and transmission electron microscopy. Our results showed that the ETAS layer acted as a barrier to slow the atomic diffusion of Ni toward the Si side. Although the formation of Ni silicides required a higher annealing temperature, the adhesion strength and contact resistivity measurements of annealed Ni-P/Si contacts showed satisfactory results, which were essential to the device performance and reliability during thermal annealing.

  14. Synthesis, structure and geometrically frustrated magnetism of the layered oxide-stannide compounds Fe(Fe3-xMnx)Si2Sn7O16.

    Science.gov (United States)

    Allison, M C; Avdeev, M; Schmid, S; Liu, S; Söhnel, T; Ling, C D

    2016-06-21

    Fe4Si2Sn7O16 has a unique crystal structure that contains alternating layers of Fe(2+) ions octahedrally coordinated by O (oxide layer) and Sn (stannide layer), bridged by SiO4 tetrahedra. The formula can be written as FeFe3Si2Sn7O16 to emphasise the distinction between the layers. Here, we report the changes in structure and properties as iron is selectively replaced by manganese in the oxide layer. Solid-state synthesis was used to produce polycrystalline samples of Fe(Fe3-xMnx)Si2Sn7O16 for x≤ 2.55, the structures of which were characterised using high-resolution synchrotron X-ray and neutron powder diffraction. Single-crystal samples were also grown at x = 0.35, 0.95, 2.60 and characterised by single crystal X-ray diffraction. We show that manganese is doped exclusively into the oxide layer, and that this layer contains exclusively magnetically active high-spin M(2+) transition metal cations; while the stannide layer only accommodates non-magnetic low-spin Fe(2+). All samples show clear evidence of geometrically frustrated magnetism, which we associate with the fact that the topology of the high-spin M(2+) ions in the oxide layer describes a perfect kagomé lattice. Despite this frustration, the x = 0 and x = 2.55 samples undergo long-range antiferromagnetic ordering transitions at 3.0 K and 2.5 K, respectively.

  15. Stress distribution in fixed-partial prosthesis and peri-implant bone tissue with different framework materials and vertical misfit levels: a three-dimensional finite element analysis.

    Science.gov (United States)

    Bacchi, Ataís; Consani, Rafael L X; Mesquita, Marcelo F; dos Santos, Mateus B F

    2013-09-01

    The purpose of this study was to evaluate the influence of superstructure material and vertical misfits on the stresses created in an implant-supported partial prosthesis. A three-dimensional (3-D) finite element model was prepared based on common clinical data. The posterior part of a severely resorbed jaw with two osseointegrated implants at the second premolar and second molar regions was modeled using specific modeling software (SolidWorks 2010). Finite element models were created by importing the solid model into mechanical simulation software (ANSYS Workbench 11). The models were divided into groups according to the prosthesis framework material (type IV gold alloy, silver-palladium alloy, commercially pure titanium, cobalt-chromium alloy, or zirconia) and vertical misfit level (10 µm, 50 µm, and 100 µm) created at one implant-prosthesis interface. The gap of the vertical misfit was set to be closed and the stress values were measured in the framework, porcelain veneer, retention screw, and bone tissue. Stiffer materials led to higher stress concentration in the framework and increased stress values in the retention screw, while in the same circumstances, the porcelain veneer showed lower stress values, and there was no significant difference in stress in the peri-implant bone tissue. A considerable increase in stress concentration was observed in all the structures evaluated within the misfit amplification. The framework material influenced the stress concentration in the prosthetic structures and retention screw, but not that in bone tissue. All the structures were significantly influenced by the increase in the misfit levels.

  16. Strain induced superconductivity in the parent compound BaFe2As2.

    Science.gov (United States)

    Engelmann, J; Grinenko, V; Chekhonin, P; Skrotzki, W; Efremov, D V; Oswald, S; Iida, K; Hühne, R; Hänisch, J; Hoffmann, M; Kurth, F; Schultz, L; Holzapfel, B

    2013-01-01

    The discovery of superconductivity with a transition temperature, Tc, up to 65 K in single-layer FeSe (bulk Tc=8 K) films grown on SrTiO3 substrates has attracted special attention to Fe-based thin films. The high Tc is a consequence of the combined effect of electron transfer from the oxygen-vacant substrate to the FeSe thin film and lattice tensile strain. Here we demonstrate the realization of superconductivity in the parent compound BaFe2As2 (no bulk Tc) just by tensile lattice strain without charge doping. We investigate the interplay between strain and superconductivity in epitaxial BaFe2As2 thin films on Fe-buffered MgAl2O4 single crystalline substrates. The strong interfacial bonding between Fe and the FeAs sublattice increases the Fe-Fe distance due to the lattice misfit, which leads to a suppression of the antiferromagnetic spin density wave and induces superconductivity with bulk Tc≈10 K. These results highlight the role of structural changes in controlling the phase diagram of Fe-based superconductors.

  17. Use of peak sharpening effects to improve the separation of chiral compounds with molecularly imprinted porous polymer layer open-tubular capillaries.

    Science.gov (United States)

    Kulsing, Chadin; Yang, Yuanzhong; Chowdhury, Jamil M; Boysen, Reinhard I; Hearn, Milton T W

    2017-02-17

    This investigation demonstrates the application of a new peak sharpening technique to improve the separation of difficult-to-resolve racemic mixtures in capillary electro-chromatography. Molecularly imprinted porous layer open tubular (MIP-PLOT) capillaries, prepared by a layer-on-layer polymerization approach with Z-l-Asp-OH as the template, were selected to validate the approach. SEM revealed that the polymer film thickness can be varied by changes in both the polymer composition and the layer-on-layer regime. Capillaries made with methacrylic acid as the functional monomer could not separate the Z-Asp-OH racemate, due to weak interactions between the MIP-PLOT material and the target analytes. In contrast, MIP-PLOT capillaries prepared with 4-vinylpyridine as the functional monomer resulted in increased ionic interactions with the target analytes. Separation of the enantiomers could be enhanced when a peak zone sharpening effect was exploited through the use of specific BGE compositions and by taking advantage of eigenpeak phenomena. In this manner, the position of a sharpening zone and the peak shape of the sample analytes could be fine-tuned, so that when the sharpening zone and the target analyte co-migrated the separation of the Z-l-Asp-OH enantiomer from its d-enantiomer in a racemic mixture could be achieved under overloading conditions.

  18. Laser deposition and direct-writing of thermoelectric misfit cobaltite thin films

    Science.gov (United States)

    Chen, Jikun; Palla-Papavlu, Alexandra; Li, Yulong; Chen, Lidong; Shi, Xun; Döbeli, Max; Stender, Dieter; Populoh, Sascha; Xie, Wenjie; Weidenkaff, Anke; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

    2014-06-01

    A two-step process combining pulsed laser deposition of calcium cobaltite thin films and a subsequent laser induced forward transfer as micro-pixel is demonstrated as a direct writing approach of micro-scale thin film structures for potential applications in thermoelectric micro-devices. To achieve the desired thermo-electric properties of the cobaltite thin film, the laser induced plasma properties have been characterized utilizing plasma mass spectrometry establishing a direct correlation to the corresponding film composition and structure. The introduction of a platinum sacrificial layer when growing the oxide thin film enables a damage-free laser transfer of calcium cobaltite thereby preserving the film composition and crystallinity as well as the shape integrity of the as-transferred pixels. The demonstrated direct writing approach simplifies the fabrication of micro-devices and provides a large degree of flexibility in designing and fabricating fully functional thermoelectric micro-devices.

  19. Magnetic phase transitions and magnetocaloric effect in layered intermetallic La0.75Sm0.25Mn2Si2 compound

    Science.gov (United States)

    Mushnikov, N. V.; Gerasimov, E. G.; Terentev, P. B.; Gaviko, V. S.; Yazovskikh, K. A.; Aliev, A. M.

    2017-10-01

    Magnetic and magnetothermal properties have been studied for the La0.75Sm0.25Mn2Si2 compound which has the spontaneous first-order antiferromagnetic to ferromagnetic (AF-F) transition at a temperature of 160 K. The transition is accompanied by the anisotropic lattice distortion. Isothermal entropy change has been estimated for different magnetic states using the heat capacity and magnetization data. Direct measurements of the adiabatic temperature change have been performed in the fields applied both along the easy c-axis and in the basal plane of a quasi-single crystal. Near the transition temperature, the AF-F transition can be realized in low magnetic fields, which makes such compounds attractive for magnetoelastic and magnetothermal applications.

  20. Elastic constants of the layered compounds GaS, GaSe, InSe, and their pressure dependence. 1. Experimental part

    Energy Technology Data Exchange (ETDEWEB)

    Gatulle, M.; Fischer, M.; Chevy, A. (Paris-6 Univ., 75 (France))

    1983-09-01

    The elastic constants of the lamellar compounds GaS, GaSe, InSe are measured on several samples using an ultrasonic method, and the results are compared with previous publications. The variations of C/sub 33/, C/sub 11/, and C/sub 66/ with hydrostatic pressure are measured up to 3 kbars. In the range of pressure studied, the variations of these constants are perfectly linear. The results on the three compounds are very similar, and typical of the lamellar structure: an important variation of C/sub 33/ caused by the weakness of the interlayer bond; on the other hand, C/sub 66/ is affected very little by pressure.

  1. Superconductivity at 55 K in Iron-Based F-Doped Layered Quaternary Compound Sm[O1-xFx]FeAs

    Institute of Scientific and Technical Information of China (English)

    REN Zhi-An; ZHOU Fang; ZHAO Zhong-Xian; LU Wei; YANG Jie; YI Wei; SHEN Xiao-Li; LI Zheng-Cai; CHE Guang-Can; DONG Xiao-Li; SUN Li-Ling

    2008-01-01

    We report the superconductivity in iron-based oxyarsenide Sm[O1-xFx]FeAs, with the onset resistivity transition temperature at 55.0K and Meissner transition at 54.6K. This compound has the same crystal structure as LaOFeAs with shrunk crystal lattices, and becomes the superconductor with the highest critical temperature among all materials besides copper oxides up to now.

  2. Capacitance-voltage studies of atomic-layer-deposited MOS structrures on Gallium Arsenide and other III-V compound semiconductors

    OpenAIRE

    Yang, Tian

    2007-01-01

    Si-based CMOS devices with traditional structure are approaching the fundamental physical limits. New device structures and materials must be explored to continue the trend of increasing electronic device speed and decreasing size at the same time. Recently, III-V compound semiconductors are considered as novel channel materials to replace Si due to their high electron mobilities. However, the main obstacle to implement III-V as novel channel materials for CMOS application is the lack of high...

  3. Loosening torque of prosthetic screws in metal-ceramic or metal-acrylic resin implant-supported dentures with different misfit levels.

    Science.gov (United States)

    Bacchi, Ataís; Paludo, Litiane; Ferraz Mesquita, Marcelo; Schuh, Christian; Federizzi, Leonardo; Oro Spazzin, Aloísio

    2013-04-26

    The aim of this study was to evaluate the effect of the prosthesis material (metal-acrylic resin or metal-ceramic) on loosening torque of the prosthetic screws in an implant-supported mandibular denture under two levels of vertical misfit. Ten frameworks were fabricated with commercially pure titanium, and five of them received acrylic resin and acrylic artificial teeth as veneering material and the other five were veneered with porcelain. Two levels of vertical fit were also created by fabricating 20 cast models to obtain four experimental groups according to the prosthesis material and misfit: Group 1 (metal-acrylic resin prosthesis with a passive fit); Group 2 (metal-acrylic resin prosthesis with a non-passive fit); Group 3 (metal-ceramic prosthesis with a passive fit); and Group 4 (metal-ceramic prosthesis with a non-passive fit). Two hundred prosthetic titanium-alloy screws were divided in 40 sets (five screws per set, n=10). After 24h, the loosening torque of the screws was evaluated using a digital torque meter. The results were submitted to two-way ANOVA analysis of variance followed by a Tukey's test (α=0.05). The mean values and standard deviations for each group were G1=7.05 (1.64), G2=5.52 (0.90), G3=6.46 (1.34), and G4=4.35 (0.99). Overall, the prosthesis material and misfit factors showed a statistically significant influence on the loosening torque (p<0.05). Metal-ceramic prosthesis and misfits decreased the loosening of the torque of the prosthetic screws.

  4. Understanding misfit strain releasing mechanisms via molecular dynamics simulations of CdTe growth on {112}zinc-blende CdS

    Science.gov (United States)

    Zhou, X. W.; Chavez, J. J.; Almeida, S.; Zubia, D.

    2016-07-01

    Molecular dynamics simulations have been used to analyse microstructures of CdTe films grown on {112} surfaces of zinc-blende CdS. Interestingly, CdTe films grow in ⟨331⟩ orientations as opposed to ⟨112⟩ epitaxial orientations. At the CdTe-{331}/CdS-{112} interface, however, there exists an axis that is parallel to the ⟨110⟩ orientation of both CdS and CdTe. It is the direction orthogonal to this ⟨110⟩ that becomes different, being ⟨116⟩ for CdTe and ⟨111⟩ for CdS, respectively. Missing CdTe-{110} planes are found along the ⟨110⟩ axis, suggesting that the misfit strain is released by the conventional misfit dislocation mechanism along this axis. In the orthogonal axis, the misfit strain is found to be more effectively released by the new grain orientation mechanism. Our finding is supported by literature experimental observations of the change of growth direction when Cd0.96Zn0.04Te films are deposited on GaAs. Analyses of energetics clearly demonstrate the cause for the formation of the new orientation, and the insights gained from our studies can help understand the grain structures experimentally observed in lattice mismatched systems.

  5. Synthesis and Crystal Structure of a Novel Layered Lead(Ⅱ) Carboxylate-sulfonate Compound Templated by 4,4'-Bipyridine

    Institute of Scientific and Technical Information of China (English)

    YING Shao-Ming; LUO Qiu-Yan; XU Ya-Ping; LIN Jun-Yue; HUANG Gan-Sheng

    2007-01-01

    A new lead(Ⅱ) carboxylate-sulfonate has been hydrothermally synthesized and characterized by X-ray single-crystal and elemental analyses. It crystallizes in triclinic, space group P,(1) with a=8.1573(6), b=9.4663(7), c=12.7488(9) (A), α=89.2320(10), β=80.7380(10), γ=77.9760(10)°, Z=2, V=950.10(12) (A)3, Mr=599.57, Dc=2.096 g/cm3, μ=9.032 mm-1, F(000)=572, the final R=0.0412 and wR=0.1035. It has a 1D chain structure, and the Pb(Ⅱ) is six-coordinated. Two PbO6 polyhedra are interconnected via edge-sharing into a two-core unit. Such units are further interconnected by 3-sulfonato-benzoic acids into 1D chains which are linked by hydrogen bonds into a layer structure. The 4,4'-bipyridines are located at the interlayer space and link the layers into a supramolecular structure by π-π stacking interactions.

  6. Hierarchical Architecturing for Layered Thermoelectric Sulfides and Chalcogenides

    Directory of Open Access Journals (Sweden)

    Priyanka Jood

    2015-03-01

    Full Text Available Sulfides are promising candidates for environment-friendly and cost-effective thermoelectric materials. In this article, we review the recent progress in all-length-scale hierarchical architecturing for sulfides and chalcogenides, highlighting the key strategies used to enhance their thermoelectric performance. We primarily focus on TiS2-based layered sulfides, misfit layered sulfides, homologous chalcogenides, accordion-like layered Sn chalcogenides, and thermoelectric minerals. CS2 sulfurization is an appropriate method for preparing sulfide thermoelectric materials. At the atomic scale, the intercalation of guest atoms/layers into host crystal layers, crystal-structural evolution enabled by the homologous series, and low-energy atomic vibration effectively scatter phonons, resulting in a reduced lattice thermal conductivity. At the nanoscale, stacking faults further reduce the lattice thermal conductivity. At the microscale, the highly oriented microtexture allows high carrier mobility in the in-plane direction, leading to a high thermoelectric power factor.

  7. HV/CVD Grown Relaxed SiGe Buffer Layers for SiGe HMOSFETs

    Institute of Scientific and Technical Information of China (English)

    黄文韬; 罗广礼; 史进; 邓宁; 陈培毅; 钱佩信

    2003-01-01

    High-vacuum/chemical-vapor deposition (HV/CVD) system was used to grow relaxed SiGe buffer layers on Si substrates. Several methods were then used to analyze the quality of the SiGe films. X-ray diffraction and Raman spectroscopy showed that the upper layer was almost fully relaxed. Second ion mass spectroscopy showed that the Ge compositions were step-graded. Transmission electron microscopy showed that the misfit dislocations were restrained to the graded SiGe layers. Tests of the electrical properties of tensile-strained Si on relaxed SiGe buffer layers showed that their transconductances were higher than that of Si devices. These results verify the high quality of the relaxed SiGe buffer layer. The calculated critical layer thicknesses of the graded Si1-xGex layer on Si substrate and a Si layer on the relaxed SiGe buffer layer agree well with experimental results.

  8. A source-orientated approach for estimating daytime concentrations of biogenic volatile organic compounds in an upper layer of a boreal forest canopy

    Energy Technology Data Exchange (ETDEWEB)

    Lappalainen, H.K. [Finnish Meteorological Inst., Helsinki (Finland); Sevanto, S.; Dal Maso, M.; Taipale, R.; Kajos, M. [Helsinki Univ. (Finland). Dept. of Physics; Kolari, P.; Back, J. [Helsinki Univ. (Finland). Dept. of Forest Ecology Sciences

    2013-06-01

    Biologically justified statistical models for daytime atmospheric concentrations of methanol, acetaldehyde, acetone, isoprene and monoterpene were tested using measurements at a boreal forest stand in southern Finland in 2006-2007 and in summer 2008. The canopy-scale concentrations of all compounds except monotepene were closely correlated with shoot-scale concentrations indicating a strong link to biological emission source. All the models were based on the exponential relationship between air temperature and atmospheric concentration of biogenic volatile organic compounds (BVOCs). The first model - an exponential function of air temperature (T model) - could explain 27%-64% of the variation in BVOC daytime concentrations in the test data. The second model - a Temperature-State of Development model (T-S model) having two explaining variables (air temperature and seasonal photosynthetic efficiency) - was derived from an empirical adjustment of seasonality. This model slightly increased the fraction of explained variation but it still could not explain the high concentration peaks, which accounted for most of the unexplained variation. To better analyse these peaks we tested the Trigger model including two potential environmental triggers, a PAR index (high photosynthetically active photon flux density (PAR) and high ozone concentration, that could increase the concentrations momentarily. However, the Trigger model described the peak concentrations only somewhat better than the T or T-S model. It seems that it is very difficult to explain more than 32%-67% of variation in BVOC concentrations by a straightforward source-oriented modelling without deep understanding of biological and physical processes. In order to improve the models profound studies on specific stress factors and events inducing BVOC emissions are needed. (orig.)

  9. Elastic constants of the layered compounds GaS, GaSe, InSe, and their pressure dependence. 2. Theoretical part

    Energy Technology Data Exchange (ETDEWEB)

    Gatulle, M.; Fischer, M.

    1984-01-01

    The block diagonalization of the dynamical matrix of ..beta..-GaS is reported in the case of propagation perpendicular to the layers. A linear chain model that includes intralayer interactions between any atoms is introduced, the principal frequencies and the elastic constants C/sub 33/ and C/sub 44/ are calculated. Within the model, the existence of real coupling parameters is discussed, that leads to an evaluation of the intralayer forces contribution to the elastic constants. The evolution of the interlayer interactions with pressure is studied, using previously published experimental results. Finally, as far as possible, the theoretical formulas are applied to the similar structures of epsilon-GaSe and ..gamma..-InSe.

  10. Strain relaxation induced surface morphology of heterogeneous GaInNAs layers grown on GaAs substrate

    Science.gov (United States)

    Gelczuk, Ł.; Jóźwiak, G.; Moczała, M.; Dłużewski, P.; Dąbrowska-Szata, M.; Gotszalk, T. P.

    2017-07-01

    The partially-relaxed heterogeneous GaInNAs layers grown on GaAs substrate by atmospheric pressure vapor phase epitaxy (AP-MOVPE) were investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The planar-view TEM image shows a regular 2D network of misfit dislocations oriented in two orthogonal crystallographic directions at the (0 0 1) layer interface. Moreover, the cross-sectional view TEM image reveals InAs-rich and V-shaped precipitates in the near surface region of the GaInNAs epitaxial layer. The resultant undulating surface morphology, known as a cross-hatch pattern, is formed as observed by AFM. The numerical analysis of the AFM image of the GaInNAs layer surface with the well-defined cross-hatch morphology enabled us to determine a lower bound of actual density of misfit dislocations. However, a close correspondence between the asymmetric distribution of interfacial misfit dislocations and undulating surface morphology is observed.

  11. The influence of the relative thermal expansion and electric permittivity on phase transitions in the perovskite-type bidimensional layered NH3(CH2)3NH3CdBr4 compound

    Science.gov (United States)

    Staśkiewicz, Beata; Staśkiewicz, Anna

    2017-07-01

    Hydrothermal method has been used to synthesized the layered hybrid compound NH3(CH2)3NH3CdBr4 of perovskite architecture. Structural, dielectric and dilatometric properties of the compound have been analyzed. Negative thermal expansion (NTE) effect in the direction perpendicular to the perovskite plane as well as an unusual phase sequence have been reported based on X-ray diffraction analysis. Electric permittivity measurements evidenced the phase transitions at Tc1=326/328 K and Tc2=368/369 K. Relative linear expansion measurements almost confirmed these temperatures of phase transitions. Anomalies of electric permittivity and expansion behavior connected with the phase transitions are detected at practically the same temperatures as those observed earlier in differential scanning calorimetry (DSC), infrared (IR), far infrared (FIR) and Raman spectroscopy studies. Mechanism of the phase transitions is explained. Relative linear expansion study was prototype to estimate critical exponent value β for continuous phase transition at Tc1. It has been inferred that there is a strong interplay between the distortion of the inorganic network, those hydrogen bonds and the intermolecular interactions of the organic component.

  12. Defect and dislocation structures in low-temperature-grown Ge and Ge{sub 1−x}Sn{sub x} epitaxial layers on Si(110) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kidowaki, Shohei [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Asano, Takanori [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Research Fellow of Japan Society for the Promotion of Science, 5-3-1, Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Shimura, Yosuke [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kurosawa, Masashi [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Taoka, Noriyuki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Nakatsuka, Osamu, E-mail: nakatuka@alice.xtal.nagoya-u.ac.jp [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Zaima, Shigeaki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2016-01-01

    We have investigated the epitaxial growth and crystalline properties of Ge{sub 1−x}Sn{sub x} layers on a Si(110) substrate. We found that the twin growth in the Ge epitaxial layer deposited on the Si(110) using molecular beam epitaxy at a low temperature of 200 °C can be effectively suppressed by the incorporation of 2.0% Sn. We also examined the strain relaxation of annealed Ge{sub 1−x}Sn{sub x}/Si(110) samples. The degree of strain relaxation is enhanced by the annealing process, and the threading dislocation in the Ge{sub 1−x}Sn{sub x} layers decreases from 10{sup 11} cm{sup −2} to 10{sup 10} cm{sup −2} because of the propagation of misfit dislocations. We also observed misfit dislocations formed at the Ge{sub 1−x}Sn{sub x}/Si interface, which would effectively promote isotropic strain relaxation in the Ge{sub 1−x}Sn{sub x} layers. - Highlights: • Suppression of twin in GeSn growth on Si(110) substrate • Isotropic strain relaxation of Ge and GeSn layers by misfit dislocation network • Achievement of high quality GeSn epitaxial layers on Si(110) by post deposition annealing.

  13. Method of forming a nanocluster-comprising dielectric layer and device comprising such a layer

    NARCIS (Netherlands)

    Kochupurackal, J.B.P.; Besling, W.F.A.; Klootwijk, J.H.; Wolters, A.M.; Roozeboom, F.

    2012-01-01

    A method of forming a dielectric layer on a further layer of a semiconductor device is disclosed. The method comprises depositing a dielectric precursor compound and a further precursor compound over the further layer, the dielectric precursor compound comprising a metal ion from the group consistin

  14. Stars and Misfits

    DEFF Research Database (Denmark)

    Åsterbro, Thomas; Chen, Jing; Thompson, Peter

    2011-01-01

    Recent evidence has shown that entrants into self-employment are disproportionately drawn from the tails of the earnings and ability distributions. This observation is explained by a multitask model of occupational choice in which frictions in the labor market induce mismatches between firms...... and workers, and misassignment of workers to tasks. The model also yields distinctive predictions relating prior work histories to earnings and to the probability of entry into self-employment. These predictions are tested with the Korean Labor and Income Panel Study, from which we find considerable support...

  15. Vertical misfit of laser-sintered and vacuum-cast implant-supported crown copings luted with definitive and temporary luting agents.

    Science.gov (United States)

    Castillo-de-Oyagüe, Raquel; Sánchez-Turrión, Andrés; López-Lozano, José-Francisco; Albaladejo, Alberto; Torres-Lagares, Daniel; Montero, Javier; Suárez-García, Maria-Jesús

    2012-07-01

    This study aimed to evaluate the vertical discrepancy of implant-supported crown structures constructed with vacuum-casting and Direct Metal Laser Sintering (DMLS) technologies, and luted with different cement types. Crown copings were fabricated using: (1) direct metal laser sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Ti (CT). Frameworks were luted onto machined implant abutments under constant seating pressure. Each alloy group was randomly divided into 5 subgroups (n = 10 each) according to the cement system utilized: Subgroup 1 (KC) used resin-modified glass-ionomer Ketac Cem Plus; Subgroup 2 (PF) used Panavia F 2.0 dual-cure resin cement; Subgroup 3 (RXU) used RelyX Unicem 2 Automix self-adhesive dual-cure resin cement; Subgroup 4 (PIC) used acrylic/urethane-based temporary Premier Implant Cement; and Subgroup 5 (DT) used acrylic/urethane-based temporary DentoTemp cement. Vertical misfit was measured by scanning electron microscopy (SEM). Two-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, and cement type on vertical misfit. The statistical significance was set at α = 0.05. The alloy/manufacturing technique and the luting cement affected the vertical discrepancy (p Laser sintering may be an alternative to vacuum-casting of base metals to obtain passive-fitting implant-supported crown copings. The best marginal adaptation corresponded to laser sintered structures luted with glass-ionomer KC, or temporary PIC or DT cements. The highest discrepancies were recorded for Co-Cr and Ti cast frameworks bonded with PF or RXU resinous agents. All groups were within the clinically acceptable misfit range.

  16. Vertical misfit of laser-sintered and vacuum-cast implant-supported crown copings luted with definitive and temporary luting agents

    Science.gov (United States)

    Sánchez-Turrión, Andrés; López-Lozano, José F.; Albaladejo, Alberto; Torres-Lagares, Daniel; Montero, Javier; Suárez-García, Maria J.

    2012-01-01

    Objectives. This study aimed to evaluate the vertical discrepancy of implant-supported crown structures constructed with vacuum-casting and Direct Metal Laser Sintering (DMLS) technologies, and luted with different cement types. Study Design. Crown copings were fabricated using: (1) direct metal laser sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Ti (CT). Frameworks were luted onto machined implant abutments under constant seating pressure. Each alloy group was randomly divided into 5 subgroups (n = 10 each) according to the cement system utilized: Subgroup 1 (KC) used resin-modified glass-ionomer Ketac Cem Plus; Subgroup 2 (PF) used Panavia F 2.0 dual-cure resin cement; Subgroup 3 (RXU) used RelyX Unicem 2 Automix self-adhesive dual-cure resin cement; Subgroup 4 (PIC) used acrylic/urethane-based temporary Premier Implant Cement; and Subgroup 5 (DT) used acrylic/urethane-based temporary DentoTemp cement. Vertical misfit was measured by scanning electron microscopy (SEM). Two-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, and cement type on vertical misfit. The statistical significance was set at α = 0.05. Results. The alloy/manufacturing technique and the luting cement affected the vertical discrepancy (p < 0.001). For each cement type, LS samples exhibited the best fit (p < 0.01) whereas CC and CT frames were statistically similar. Within each alloy group, PF and RXU provided comparably greater discrepancies than KC, PIC, and DT, which showed no differences. Conclusions. Laser sintering may be an alternative to vacuum-casting of base metals to obtain passive-fitting implant-supported crown copings. The best marginal adaptation corresponded to laser sintered structures luted with glass-ionomer KC, or temporary PIC or DT cements. The highest discrepancies were recorded for Co-Cr and Ti cast frameworks bonded with PF or RXU resinous agents. All groups were within the clinically

  17. Solvothermal syntheses, crystal structures, and thermal stability of two new thioantimonates(III) using complex transition metal cations as structure directing agents: the layered compound [Ni(dien) 2]Sb 4S 7·H 2O and the three-dimensional compound [Ni(dien) 2] 3Sb 12S 21·H 2O

    Science.gov (United States)

    Stähler, Ralph; Näther, Christian; Bensch, Wolfgang

    2003-09-01

    The two new thioantimonates(III) [Ni(dien) 2]Sb 4S 7·H 2O ( I) and [Ni(dien) 2] 3Sb 12S 21·H 2O ( II) were prepared under solvothermal conditions using elemental Ni, Sb, S and an aqueous solution of diethylenetriamine (dien) as solvent. Compound I crystallizes in the monoclinic space group P2 1/ c, a=9.603(2) Å, b=16.137(3) Å, c=17.272(4) Å, β=91.68(3)°, V=2675.3(9) Å 3, Z=4 and compound II crystallizes in the monoclinic space group C2/ c with a=12.6072(7) Å, b=14.9967(7) Å, c=41.445(2) Å, β=95.371(6)°, V=7801.4(7) Å 3, Z=4. The two-dimensional ∞2[Sb 4S 72-] anion in I is composed of two SbS 3 trigonal pyramids and two SbS 4 units. The SbS 3 units are connected via one corner to form a Sb 2S 5 unit and the two SbS 4 moieties share a common edge building a trans-Sb 2S 6 unit. The Sb 2S 5 and trans-Sb 2S 6 units have one common S atom to form the layered ∞2[Sb 4S 72-] anion. Within the layers Sb 2S 2, Sb 4S 4 and Sb 8S 8 heterorings are found with the mer-[Ni(dien) 2] 2+ residing above and below the large pores. In compound II the ∞3[Sb 12S 216-] anion is composed of four SbS 3 pyramids and two SbS 4 units. The condensation of the different primary units yields Sb xS x rings with x=2,3,4,8, and 32. The largest ring consists of 64 atoms (Sb 32S 32) and the pores with an ellipsoidal shape are oriented parallel to the [110] direction. To the best of our knowledge this is the largest Sb xS x heteroring found in thioantimonates(III) so far. The cations are located above and below the large ring or within the plane of the ring. Nearly rectangular channels are running along [101] which have dimensions of about 7.6·13.5 Å. The channels are occupied by the water molecule and by the ligands pointing into the channels. The thermal behavior of the compounds was investigated using differential thermoanalysis (DTA), thermogravimetry (TG) and mass spectroscopy (MS) measurements. Upon heating decomposition of the compounds starts at Tonset=235°C (I) and Tonset

  18. Regularization strategy for the layered inversion of airborne TEM data: application to VTEM data acquired over the basin of Franceville (Gabon)

    CERN Document Server

    Guillemoteau, Julien; Behaegel, Mickael; 10.1111/j.1365-2478.2011.00990.x

    2012-01-01

    Airborne transient electromagnetic (TEM) is a cost-effective method to image the distribution of electrical conductivity in the ground. We consider layered earth inversion to interpret large data sets of hundreds of kilometre. Different strategies can be used to solve this inverse problem. This consists in managing the a priori information to avoid the mathematical instability and provide the most plausible model of conductivity in depth. In order to obtain fast and realistic inversion program, we tested three kinds of regularization: two are based on standard Tikhonov procedure which consist in minimizing not only the data misfit function but a balanced optimization function with additional terms constraining the lateral and the vertical smoothness of the conductivity; another kind of regularization is based on reducing the condition number of the kernel by changing the layout of layers before minimizing the data misfit function. Finally, in order to get a more realistic distribution of conductivity, notably...

  19. Atomistic studies of grain boundaries and heterophase interfaces in alloys and compounds. Final report, July 1987-August 1998

    Energy Technology Data Exchange (ETDEWEB)

    Vitek, Vaclav

    1998-08-01

    The overarching goal of the research supported by this grant was investigation of the structure and properties of interfaces in multicomponent systems by atomistic modeling. Initially, the research was devoted to studies of segregation to grain boundaries in binary disordered alloys. The next step was then studies of the structure and properties of grain boundaries in ordered compounds, specifically Ni3Al and NiAl, and grain boundary segregation in these compounds in the case of off-stoichiometry. Finally, the structure of Nb/sapphire interfaces, in particular the core configurations of the misfit dislocations, was studied.

  20. Application of synchrotron-radiation-based x-ray microprobe techniques for the analysis of recombination activity of metals precipitated at Si/SiGe misfit dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Vyvenko, O F [University of California, LBNL, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Buonassisi, T [University of California, LBNL, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Istratov, A A [University of California, LBNL, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Weber, E R [University of California, LBNL, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Kittler, M [IHP, Im Technologiepark 25, D-15236 Frankfurt (Oder) (Germany); Seifert, W [IHP, Im Technologiepark 25, D-15236 Frankfurt (Oder) (Germany)

    2002-12-09

    In this study we report application of synchrotron-radiation-based x-ray microprobe techniques (the x-ray-beam-induced current (XBIC) and x-ray fluorescence ({mu}-XRF) methods) to the analysis of the recombination activity and space distribution of copper and iron in the vicinity of dislocations in silicon/silicon-germanium structures. A combination of these two techniques enables one to study the chemical nature of the defects and impurities and their recombination activity in situ and to map metal clusters with a micron-scale resolution. XRF analysis revealed that copper formed clearly distinguishable precipitates along the misfit dislocations. A proportional dependence between the XBIC contrast and the number of copper atoms in the precipitates was established. In hydrogen-passivated iron-contaminated samples we observed clusters of iron precipitates which had no recombination activity detectable by the XBIC technique as well as iron clusters which were not completely passivated.

  1. Copper diphosphonates with zero-, one- and two-dimensional structures: ferrimagnetism in layer compound Cu3(ImhedpH)(2).2H2O [ImhedpH4=(1-C3H3N2)CH2C(OH)(PO3H2)2].

    Science.gov (United States)

    Cao, Deng-Ke; Xie, Xiao-Ji; Li, Yi-Zhi; Zheng, Li-Min

    2008-10-07

    Reactions of CuSO4 with 2-(1-imidazole)-1-hydroxy-1,1'-ethylidenediphosphonic acid (ImhedpH4) under hydrothermal conditions at different temperatures lead to four new metal phosphonates: Cu(ImhedpH3)2(H2O).2H2O (), Cu(ImhedpH3)2 (), Cu3(ImhedpH2)2(ImhedpH3)(2).4H2O (), and Cu3(ImhedpH)(2).2H2O (). Compounds and have mononuclear structures in which the Cu atoms adopt square pyramidal and square planar geometries, respectively. In compound , a chain structure is observed where the Cu3(ImhedpH2)2(ImhedpH3)2 trimer units are connected by edge-sharing of the {Cu2O5} square pyramids. Compound exhibits a layer structure made up of Cu3(ImhedpH)2 trimer units. The connection of trimers through corner-sharing of {Cu1O4} and {CPO3} tetrahedra results in a two-dimensional layer containing 8- and 16-membered rings. The imidazole groups are grafted on the two sides of the layer. Magnetic studies reveal that ferromagnetic interactions are mediated in , while for compound , ferrimagnetism is observed below 5.8 K.

  2. Advanced titania buffer layer architectures prepared by chemical solution deposition

    Science.gov (United States)

    Kunert, J.; Bäcker, M.; Brunkahl, O.; Wesolowski, D.; Edney, C.; Clem, P.; Thomas, N.; Liersch, A.

    2011-08-01

    Chemical solution deposition (CSD) was used to grow high-quality (100) oriented films of SrTiO3 (STO) on CSD CaTiO3 (CTO), Ba0.1Ca0.9TiO3 (BCT) and STO seed and template layers. These template films bridge the lattice misfit between STO and the nickel-tungsten (NiW) substrate, assisting in dense growth of textured STO. Additional niobium (Nb) doping of the STO buffer layer reduces oxygen diffusion which is necessary to avoid undesired oxidation of the NiW. The investigated templates offer suitable alternatives to established standard buffer systems like La2Zr2O7 (LZO) and CeO2 for coated conductors.

  3. Periodicity effects on compound guided waves

    Science.gov (United States)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio; Lakhtakia, Akhlesh

    2016-09-01

    Surface waves of different types can be compounded when a homogeneous layer is sandwiched between two half spaces filled with dissimilar periodically non-homogeneous dielectric materials and the intermediate layer is sufficiently thin. We solved the boundary-value problem for compound waves guided by a layer of a homogeneous and isotropic (metal or dielectric) material sandwiched between a structurally chiral material (SCM) and a periodically multi-layered isotropic dielectric material. We found that the periodicity of the SCM is crucial to excite a multiplicity of compound guided waves with strong coupling between the two interfaces.

  4. Semiconducting compounds and devices incorporating same

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

    2014-06-17

    Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

  5. Semiconducting compounds and devices incorporating same

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J.; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

    2016-01-19

    Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

  6. Polybenzimidazole compounds

    Science.gov (United States)

    Klaehn, John R.; Peterson, Eric S.; Wertsching, Alan K.; Orme, Christopher J.; Luther, Thomas A.; Jones, Michael G.

    2010-08-10

    A PBI compound that includes imidazole nitrogens, at least a portion of which are substituted with an organic-inorganic hybrid moiety. At least 85% of the imidazole nitrogens may be substituted. The organic-inorganic hybrid moiety may be an organosilane moiety, for example, (R)Me.sub.2SiCH.sub.2--, where R is selected from among methyl, phenyl, vinyl, and allyl. The PBI compound may exhibit similar thermal properties in comparison to the unsubstituted PBI. The PBI compound may exhibit a solubility in an organic solvent greater than the solubility of the unsubstituted PBI. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may occur at about room temperature and/or at about atmospheric pressure. Substituting may use at least five equivalents in relation to the imidazole nitrogens to be substituted or, preferably, about fifteen equivalents.

  7. Thermoelectric properties of Al substituted misfit cobaltite Ca3(Co1-xAlx)4O9 at low temperature

    Institute of Scientific and Technical Information of China (English)

    Yi Liu; Hong-mei Chen; Jin-lian Hu; Xu-bing Tang; Hai-jin Li; Wei Wang

    2014-01-01

    Thermoelectric properties of Al substituted compounds Ca3(Co1−xAlx)4O9 (x=0, 0.03, 0.05), prepared by a sol−gel process, have been investigated in the temperature range 305−20 K. The results indicate that after Al substitution for Co in Ca3(Co1−xAlx)4O9, the direct current electrical resistivity and thermopower increase due to the reduction of carrier concentration. Experiments show that Al substitution results in decreased lattice thermal conductivity. The figure of merit of temperature behavior suggests that Ca3(Co0.97Al0.03)4O9 would be a promising candidate thermoelectric material for high-temperature thermoelectric application.

  8. Multipurpose Compound

    Science.gov (United States)

    1983-01-01

    Specially formulated derivatives of an unusual basic compound known as Alcide may be the answer to effective treatment and prevention of the disease bovine mastitis, a bacterial inflammation of a cow's mammary gland that results in loss of milk production and in extreme cases, death. Manufactured by Alcide Corporation the Alcide compound has killed all tested bacteria, virus and fungi, shortly after contact, with minimal toxic effects on humans or animals. Alcide Corporation credits the existence of the mastitis treatment/prevention products to assistance provided the company by NERAC, Inc.

  9. Light metal compound casting

    Institute of Scientific and Technical Information of China (English)

    Konrad; J.; M.; PAPIS; Joerg; F.; LOEFFLER; Peter; J.; UGGOWITZER

    2009-01-01

    Compound casting’simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, ‘compound casting’ of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu- ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and Al12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protective coating to the substrate.

  10. Light metal compound casting

    Institute of Scientific and Technical Information of China (English)

    Konrad J.M.PAPIS; Joerg F.LOEFFLER; Peter J.UGGOWITZER

    2009-01-01

    'Compound casting'simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, 'compound casting' of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu-ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and AI12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protec-tive coating to the substrate.

  11. Effect of Misfit Strain on Pyroelectric Properties of (111) Oriented Pb(Zr1-x Ti x ) O3 Thin Films

    Science.gov (United States)

    Qiu, Jian-Hua; Chen, Zhi-Hui; Wang, Xiu-Qin; Yuan, Ning-Yi; Ding, Jian-Ning

    2016-10-01

    Based on the Landau-Dovenshire theory, the thermodynamic potential of (111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr1-xTix) O3 thin films. Due to the presence of nonlinear coupling terms resulted from the (111) epitaxy with substrates, the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of (001) and (110) oriented films. Pb(Zr0.5Ti0.5) O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the giant dielectric and pyroelectric properties. Moreover, Pb(Zn1-xTix) O3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates. Therefore, the physical properties of (111) oriented Pb(Zr1-xTix) O3 thin films can be adjusted by choosing the suitable substrates. Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, the research fund of Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology, Major Projects of Natural Science Research in Jiangsu Province under Grant Nos. 15KJA43002, 16KJD430006, and also sponsored by Qing Lan Project of Education Department of Jiangsu Province

  12. Influences of Interfacial Misfit Dislocations on Cathodoluminescence of ZnS/GaAs(001) Studied by Transmission Electron Microscopy

    Science.gov (United States)

    Mitsui, Tadashi; Yamamoto, Naoki

    2000-03-01

    The change in cathodoluminescence (CL) spectra of thin ZnS films grown by molecular beam epitaxy (MBE) on GaAs(001) has been examined by a low-temperature CL measurement system combined with a transmission electron microscope (TEM). It was found that structural defects such as dislocations and stacking faults formed in the ZnS films seriously affect CL intensity within a distance of 200 nm from the interface, and their effect becomes negligibly small at distances of more than 600 nm. The relative intensities of the exciton-associated emissions are small in comparison with the non-exciton-associated emissions for the thin samples that have relatively large stacking fault densities. This fact suggests that the stacking faults accompanying the partial dislocations suppress the generation of excitons. Moreover, the peak of the non-exciton-associated emission shifts markedly to long wavelengths, as the epitaxial layer thickness becomes less than 200 nm. The peak shift is attributed to the internal stress change in the ZnS film due to the stress caused by the lattice mismatch and the relaxation by the introduced defects.

  13. Suitability of thin-layer chromatography-flame ionization detection with regard to quantitative characterization of different fossil fuel products. 1. FID performances and response of pure compounds related to fossil fuel products

    Energy Technology Data Exchange (ETDEWEB)

    Cebolla, V.L.; Vela, J.; Membrado, L.; Ferrando, A.C. [CSIC, Zaragoza (Spain). Inst. de Carboquimica, Dept. de Procesos Quimicos

    1998-10-01

    The performance of a modern TLC-FID system (which includes the newest detector configuration) was tested on polycyclic aromatic compound standards and related compounds as a preliminary step to evaluate its suitability for quantitative hydrocarbon group type analysis of different coal and petroleum products. FID linearity was evaluated as a function of sample load and scan speed for high-molecular-weight and semi-volatile standards. TLC-FID response factors for compounds of several homologous series were studied in order to differentiate effects of volatility from those exclusively due to the chemical nature concerning FID response. Criteria are developed for the accurate application of TLC-FID to fossil fuel samples. Measurements of chromarod temperatures were carried out in order to evaluate whether an evaporation of compounds outside the H{sub 2} flame might take place. 10 refs., 3 figs., 4 tabs.

  14. Formation of extended defects in SiGe/Si heterostructures with SiGeC intermediate layers

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, V.I.; Reznik, V.Ya. [Institute for Chemical Problems of Microelectronics, Moscow (Russian Federation); Torack, T.A.; Fei, Lu [MEMC Inc, St Peters, MO (United States); Mil' vidskii, M.G. [Institute of Rare Metals ' Giredmet' , Moscow (Russian Federation); Falster, R. [MEMC Electronic Materials SpA, Novara (Italy)

    2007-07-01

    The generation of misfit dislocations (MDs) and stacking faults (SFs) was studied by TEM and preferential chemical etching in multilayer Si(001)/SiGe/SiGeC(10 nm)/SiGe/Si heterostructures grown by CVD at 650 C. Prior to growth of Si layer, the other part of heterostructure was annealed at 950 C in the growth chamber to get relaxed buffer layers and strained Si layer free of extended defects. We used SiGe alloys with Ge content of 24 at.% and C content of 0.5 at.%. Carbon in the strained SiGe matrix was found to promote high rates of strain relaxation through the nucleation of perfect dislocation loops close to the interface with Si substrate. For Si layer thickness >10 nm, threading dislocations split in these layers under tensile strain to form SFs. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Theory versus experiment for a family of single-layer compounds with a similar atomic arrangement: (Tl,X )/Si(111 )√{3 }×√{3 }(X =Pb,Sn,Bi,Sb,Te,Se)

    Science.gov (United States)

    Matetskiy, A. V.; Kibirev, I. A.; Mihalyuk, A. N.; Eremeev, S. V.; Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Zotov, A. V.; Saranin, A. A.

    2017-08-01

    Two-dimensional compounds made of one monolayer of Tl and one-third monolayer of Pb, Bi, Te, or Se (but not of Sn or Sb) on Si(111) have been found to have a similar atomic arrangement which can be visualized as a √{3 }×√{3 } -periodic honeycomb network of chained Tl trimers with atoms of the second adsorbate occupying the centers of the honeycomb units. Structural and electronic properties of the compounds have been examined in detail theoretically using density functional theory (DFT) calculations and experimentally using low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and angle-resolved photoelectron spectroscopy (ARPES) observations. It has been found that though structural parameters of the compounds are very similar for all species, the only common feature of their band structure is a considerable spin-splitting of the surface-state bands, while other basic electronic properties vary greatly with a change of species. The Tl-Pb compound is strongly metallic with two metallic surface-state bands; the Tl-Bi compound is also metallic but with a single metallic band; the Tl-Te and Tl-Se compounds appear to be insulators.

  16. Controllable Synthesis and Release Properties of Methotrexatum/Layered Double Hydroxide Compounds%甲氨蝶呤/层状双金属氢氧化物的粒径调控及缓释性能研究

    Institute of Scientific and Technical Information of China (English)

    齐凤林; 李淑萍; 张晓晴

    2012-01-01

    在乙醇-水混合体系中, 以氨水为沉淀剂共沉淀合成了甲氨蝶呤/层状双金属氢氧化物(MTX/LDH)纳米复合物, 首次采用控制沉淀剂滴加速率的方式来调控其粒径。 利用X-射线衍射(XRD)、透射电镜(TEM)和红外光谱(FT-IR)等表征手段, 对其结构及形貌进行了表征。 研究表明: MTX分子以单层倾斜方式插入LDH层间, 随着滴加速率不同, MTX在层间的倾斜角度发生了变化; 沉淀剂滴加速率对产物的结晶度、粒径和层间排列方式都有影响, 当沉淀剂滴加速率为0.100 mL/s时, 得到的MTX/LDH纳米复合物的结晶度最高, 粒径最大。 在磷酸缓冲液中考察了不同粒径MTX/LDH纳米复合物的缓释性能, 结果表明: 小粒径的MTX/LDH纳米复合物的载药量要高于大粒径的; 当MTX阴离子在层间的倾斜角度相似时, 粒径小的粒子释放速率较慢, 缓释效果优于粒径大的。 尤为重要的是我们探索出一条保证复合物阴离子在层间的倾斜角度相似的情况下, 制备不同粒径纳米复合物的新途径。%The methotrexatum/layered double hydroxide (MTX/LDH) compounds with different particle sizes were prepared by controlling the dropping speed of precipitator, using the coprecipitation method in alcohol-water solvent and NH3·H2O as precipitator. The influence of the dropping speed of precipitator on the structure and morphologies of MTX/LDHs was systematically characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM) and fourier transform infrared spectroscopy (FT-IR). The results indicated that MTX anions were intercalated into the LDH interlayers with a declined monolayer and the angle of inclination changed with the variation of the dropping speed of precipitator. Furthermore, the dropping speed of precipitator affected the crystallinity and particle size as well as arrangement way of MTX in LDH interlayers, when the dropping speed is 0.100 m

  17. 复方党参口服液对免疫应激蛋雏鸡免疫分子的影响%Effects of Compound Codonopsis Oral Liquids on Immune Molecules with Immunological Stress in Layer Chickens

    Institute of Scientific and Technical Information of China (English)

    张孝清; 童小明; 温伟业

    2016-01-01

    levels of IgG ,IL‐2 and ACTH of serum with immuno‐logical stress in layer chickens .One hundred and fifty healthy chickens at one day old with the same body weight were divided into five groups of 30 chickens per group :High dose group ,medi‐um dose group ,low dose group ,model control group and base control group ,respectively .From the 3 days old ,the high ,medium and low dose groups were respectively administered 8 ,4 and 2 mg/(kg · BW) compound Codonopsis oral liquids for 10 days;The chickens of 3 different dose groups and model control group were intramuscularly injected Newcastle disease (ND) vaccinesⅠ to make immunosuppressive models on 7th day .The samples were collected and IgG ,IL‐2 and ACTH contents in serum were determined on the 8th ,16th ,24th ,32th and 40th day .The results showed that on the 16th ,24th and 32th day ,the IgG content of 3 different dose groups were ex‐tremely significantly higher than that of model control group (Pmiddle dose group>low dose group .On the 8th and 16th day ,the IL‐2 level of high and middle dose groups were extremely significantly or significantly higher than that of model control group (P<0 .05 ;P<0 .01) ,and on the 24th and 40th day ,3 different dose groups were extremely signif‐icantly higher than that of model control group (P<0 .01) ,and that of high dose group was ex‐tremely significantly higher (P< 0 .01)while middle dose group was significantly higher (P<0.05)than the model control group on the 32th day ;On the 8th ,16th ,24th and 40th day ,the ACT H content of high and middle dose groups were extremely significantly or significantly lower than that of model control group (P<0 .05 ;P<0 .01) ,and that of high dose group was signifi‐cantly lower than model control group on the 32th day (P<0 .05) .At the late experiment period , the ACT H content of 3 different dose groups were gradually became similar to base control group ,in‐dicating that the effect of immunosuppressant on ACTH was transient

  18. Intermetallic Compounds

    Science.gov (United States)

    Takagiwa, Y.; Matsuura, Y.; Kimura, K.

    2014-06-01

    We have focused on the binary narrow-bandgap intermetallic compounds FeGa3 and RuGa3 as thermoelectric materials. Their crystal structure is FeGa3-type (tetragonal, P42/ mnm) with 16 atoms per unit cell. Despite their simple crystal structure, their room temperature thermal conductivity is in the range 4-5-W-m-1-K-1. Both compounds have narrow-bandgaps of approximately 0.3-eV near the Fermi level. Because their Seebeck coefficients are quite large negative values in the range 350-FeGa3 and RuGa3 as n and p-type materials. The dimensionless figure of merit, ZT, was significantly improved by substitution of Sn for Ga in FeGa3 (electron-doping) and by substitution of Zn for Ga in RuGa3 (hole-doping), mainly as a result of optimization of the electronic part, S 2 σ.

  19. Ion beam synthesis of SiGe alloy layers

    Energy Technology Data Exchange (ETDEWEB)

    Im, Seongil [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Procedures required for minimizing structural defects generated during ion beam synthesis of SiGe alloy layers were studied. Synthesis of 200 mm SiGe alloy layers by implantation of 120-keV Ge ions into <100> oriented Si wafers yielded various Ge peak concentrations after the following doses, 2 x 1016cm-2, 3 x 1016cm-2 (mid), and 5 x 1016cm-2 (high). Following implantation, solid phase epitaxial (SPE) annealing in ambient N2 at 800C for 1 hr. resulted in only slight redistribution of the Ge. Two kinds of extended defects were observed in alloy layers over 3 x l016cm-2cm dose at room temperature (RT): end-of-range (EOR) dislocation loops and strain-induced stacking faults. Density of EOR dislocation loops was much lower in alloys produced by 77K implantation than by RT implantation. Decreasing the dose to obtain 5 at% peak Ge concentration prevents strain relaxation, while those SPE layers with more than 7 at% Ge peak show high densities of misfit- induced stacking faults. Sequential implantation of C following high dose Ge implantation (12 at% Ge peak concentration in layer) brought about a remarkable decrease in density of misfit-induced stacking faults. For peak implanted C > 0.55 at%, stacking fault generation in the epitaxial layer was suppressed, owing to strain compensation by C atoms in the SiGe lattice. A SiGe alloy layer with 0.9 at% C peak concentration under a 12 at% Ge peak exhibited the best microstructure. Results indicate that optimum Ge/C ratio for strain compensation is between 11 and 22. The interface between amorphous and regrown phases (a/c interface) had a dramatic morphology change during its migration to the surface. Initial <100> planar interface decomposes into a <111> faceted interface, changing the growth kinetics; this is associated with strain relaxation by stacking fault formation on (111) planes in the a/c interface.

  20. Organic Compounds

    Science.gov (United States)

    Shankland, Kenneth

    For many years, powder X-ray diffraction was used primarily as a fingerprinting method for phase identification in the context of molecular organic materials. In the early 1990s, with only a few notable exceptions, structures of even moderate complexity were not solvable from PXRD data alone. Global optimisation methods and highly-modified direct methods have transformed this situation by specifically exploiting some well-known properties of molecular compounds. This chapter will consider some of these properties.

  1. Compound odontoma

    Directory of Open Access Journals (Sweden)

    Monica Yadav

    2012-01-01

    Full Text Available Odontomas have been extensively reported in the dental literature, and the term refers to tumors of odontogenic origin. Though the exact etiology is still unknown, the postulated causes include: local trauma, infection, inheritance and genetic mutation. The majority of the lesions are asymptomatic; however, may be accompanied with pain and swelling as secondary complaints in some cases. Here, we report a case of a compound odontome in a 14 year old patient.

  2. Nonmixing layers

    Science.gov (United States)

    Gaillard, Pierre; Giovangigli, Vincent; Matuszewski, Lionel

    2016-12-01

    We investigate the impact of nonideal diffusion on the structure of supercritical cryogenic binary mixing layers. This situation is typical of liquid fuel injection in high-pressure rocket engines. Nonideal diffusion has a dramatic impact in the neighborhood of chemical thermodynamic stability limits where the components become quasi-immiscible and ultimately form a nonmixing layer. Numerical simulations are performed for mixing layers of H2 and N2 at a pressure of 100 atm and temperature around 120-150 K near chemical thermodynamic stability limits.

  3. Water soluble inorganic trace gases and related aerosol compounds in the tropical boundary layer. An analysis based on real time measurements at a pasture site in the Amazon Basin

    NARCIS (Netherlands)

    Trebs, I.

    2005-01-01

    This dissertation investigates the behavior of water-soluble inorganic trace gases and related aerosol species in the tropical boundary layer. Mixing ratios of ammonia (NH3), nitric acid (HNO3), nitrous acid (HONO), hydrochloric acid (HCl), sulfur dioxide (SO;,) and the corresponding water-soluble a

  4. Three-dimensional nanostructures on Ge/Si(100) wetting layers: Hillocks and pre-quantum dots

    Science.gov (United States)

    Ramalingam, Gopalakrishnan; Floro, Jerrold A.; Reinke, Petra

    2016-05-01

    The annealing of sub-critical Ge wetting layers (WL cake-type structure where the step edges run parallel to the ⟨110⟩ direction, are formed from thin wetting layers, while {105}-faceted structures, called pre-quantum dots (p-QDs), are formed from thicker layers. The wetting layer thickness and thus the misfit strain energy controls the type of structure. The crossover thickness between the hillock and p-QDs regime is between 1.6 and 2.1 ML. The hillocks have larger lateral dimensions and volumes than p-QDs, and the p-QDs are exceptionally small quantum dots with a lower limit of 10 nm in width. Our work opens a new pathway to the control of nanostructure morphology and size in the elastically strained Ge/Si system.

  5. Magnesium compounds

    Science.gov (United States)

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  6. Preparation of Mg-Al layered double hydroxides intercalated with 1,3,6-naphthalenetrisulfonate and 3-amino-2,7-naphthalenedisulfonate and assessment of their selective uptake of aromatic compounds from aqueous solutions

    Science.gov (United States)

    Kameda, Tomohito; Yamazaki, Takashi; Yoshioka, Toshiaki

    2010-05-01

    Mg-Al layered double hydroxides (Mg-Al LDHs) intercalated with 1,3,6-naphthalenetrisulfonate (NTS 3-) and 3-amino-2,7-naphthalenedisulfonate (ANDS 2-) ions were prepared by coprecipitation and were characterized by X-ray diffraction and chemical analyses. Based on X-ray diffraction patterns, the naphthalene rings of NTS 3- and ANDS 2- were most likely oriented parallel to the brucite-like host layers of the Mg-Al LDH, midway between layers. The prepared Mg-Al LDHs were able to selectively take up aromatics from aqueous solutions, and the order of percentage uptake was as follows: 1,3-dinitrobenzene > nitrobenzene > benzaldehyde > N,N-dimethylaniline > anisole > 1,2-dimethoxybenzene. The differences in the extent of π-π stacking interactions occurring between the benzene rings of the aromatics and the naphthalene ring of the intercalated NTS 3- and ANDS 2- probably resulted in these differences among the absorbed quantities of the various aromatics.

  7. Crystalline thin films: The electrochemical atomic layer deposition (ECALD) view

    CSIR Research Space (South Africa)

    Modibedi, M

    2011-09-01

    Full Text Available Electrochemical atomic layer deposition technique is selected as one of the methods to prepare thin films for various applications, including electrocatalytic materials and compound....

  8. The Misfits in Knowledge Work

    DEFF Research Database (Denmark)

    Fischer, Louise Harder; Pries-Heje, Lene

    2015-01-01

    The workplace is changing rapidly and knowledge work is conducted increasingly in settings that are global, digital, flat and networked. The epicenter of value-creation are the individuals and their interactions. Unified Communication and Collaboration Technology (UC&C) supports individual intera...

  9. Parameters of passive fit using a new technique to mill implant-supported superstructures: an in vitro study of a novel three-dimensional force measurement-misfit method.

    Science.gov (United States)

    Tahmaseb, Ali; van de Weijden, J J; Mercelis, Peter; De Clerck, Renaat; Wismeijer, Daniel

    2010-01-01

    The objectives of this study are to describe, in vitro, a novel technique to measure the misfit of digitally designed and manufactured implant-supported frameworks according to a new concept based on computer-guided surgery in combination with previously placed mini-implants. Also, the digitally created framework and an impression-based milled structure were compared using strain gauge measurements. Acrylic resin and plaster models were prepared to represent the edentulous mandible. After insertion of three mini-implants in the acrylic resin model, a cone-beam computed tomographic scan was performed. The data were imported to planning software, where six implants were virtually inserted. A drill guide and titanium framework were designed and milled using a fully digital computer-aided design/computer-assisted machining protocol. Six implants were inserted using the drill guide attached to the mini-implants. After an impression was made of the acrylic resin model with six implants, the second model (plaster model) was prepared. A second milled titanium structure was fabricated following optical scanning of the acrylic resin model. Strain gauge measurements were done on both structures attached to both models. To validate the results, a high-accuracy industrial optical scanning system was used to capture all connection geometry and the measurements were compared. The accuracy of the digital superstructures was 19, 22, and 10 Microm with standard deviations (SD) of 19.2 (17.9), 21.5 (28.3), and 10.3 (10.1) Microm for the x-, y-, and z-axes, respectively. For the impression-based superstructure the measured misfit was 11, 20, and 17 Microm, with SD 11.8 (10.5), 19.7 (11.7), and 16.7 (8.2) Microm for the x-, y-, and z-axes, respectively. The misfit of the digitally designed and produced superstructure on the digitally planned and inserted implants was clinically insignificant.

  10. Disorder and transport of silver in some layered metal sulfides

    NARCIS (Netherlands)

    Gerards, Anthonius Gijsbertus

    1987-01-01

    The chemical and physical properties of compounds with a layered structure are strongly determined by the two-dimensional nature of the bonding, viz. strong bonding within the layers and much weaker bonds between the layers; graphite is an example of such and anisotropic solid. the layered transitio

  11. Synthesis and Characterization of the Double-Layer 2D Compound with Helix%2维双螺旋层配合物的构筑及表征

    Institute of Scientific and Technical Information of China (English)

    张美丽; 任宜霞; 王记江

    2011-01-01

    在水热条件下合成一种新型2维(2D)聚合物[Ni2(pda)2(bpp)2(H2O)3] (1)(1,4-pda=对苯二乙酸、bpp=1,3-二(4-吡啶基)丙烷).采用红外光谱、差热-热重、CHN元素分析及单晶X-射线衍射等手段对晶体结构进行了表征.配合物1属3斜晶系,空间群为P-1;晶体学参数:a=9.925(4)nm,b=12.863(6) nm,c=18.710(8) nm; a=101.813(9)°,β=99.133(9)°,y=90.240(9)°.其基本结构单元由2个Ni(Ⅱ)原子、3个对苯二乙酸根、4个1,3-二(4-吡啶基)丙烷和3个配位水分子组成.对苯二乙酸根与Ni(Ⅱ)原子交替连接形成1维右手螺旋链,相邻同手性螺旋链通过TG构型的1,3-二(4-吡啶基)丙烷连接形成2维右手螺旋层A.同样,对苯二乙酸根、Ni(Ⅱ)原子、1,3-二(4-吡啶基)丙烷形成2维左手螺旋层B.这2个相邻螺旋层A、B间通过[Ni2bpp2]闭合环的支撑形成双层2维结构.%A novel two-dimensional(2D) polymer [Ni2(pda)2(bpp)2(H2O)3] (1) (H2pda=l,4-phenylenediacetic acid,bpp=l,3-bi(4-pyridyl)propane) was obtained through hydrothermal reaction and characterized by means of elemental analysis,IR,TG-DSC and single crystal X-ray diffraction. The results show that the complex 1 is triclinic and crystallize in central symmetrical space group P-\\, a=9.925(4) nm, 6=12.863(6) nm, e=18.710(8) nm; a=101.813(9)°, yS=99.133(9)°, y=90.240(9)°. The crystal structure of complex 1 consists of two Nickel(II), threel, 4-pda ligands, four 1.3-di(4-pyridy) butane ligands and three water moleculars. The 1,4-pda anions bridge the Ni (II) ions to form a ID right-handed helical chain. Moreover, these helical chains are united together through the TG bpp ligands to afford a right-handed 2D helical layer(namely, A layer). At the same time, the 1,4-pda anions, Ni(II) ions and bpp ligands form a left-handed 2D helical layer (namely, B layer). The overall architecture is constructed from alternate A and B helical layers pillared by the closed [Ni2bpp2] rings, affords a double-layer 2D.

  12. Pseudo-hcp nonmagnetic intermediate layer for granular media with high perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Atsushi [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Saito, Shin [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Itagaki, Norikazu [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Takahashi, Migaku [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2008-01-07

    Materials with the hexagonal close-packed structure (hcp) and the face-centred-cubic structure with stacking faults (pseudo-hcp) are examined for the nonmagnetic intermediate layer (NMIL) in order to suppress variant growth of magnetic grains for granular-type perpendicular recording media. Judging from the analysis of the epitaxial growth of Co-based magnetic grains, it has been found that a lattice misfit between NMIL and magnetic grain of less than 6% and a spreading coefficient of wettability of magnetic grain on NMIL of greater than 0.3 J m{sup -3} are required for the recording layer to have high perpendicular magnetic anisotropy energy. (fast track communication)

  13. A comparative quantitative structure-retention relationships study for lipophilicity determination of compounds with a phenanthrene skeleton on cyano-, reversed phase-, and normal phase-thin layer chromatography stationary phases.

    Science.gov (United States)

    Ciura, Krzesimir; Nowakowska, Joanna; Pikul, Piotr; Struck-Lewicka, Wiktoria; Markuszewski, Michał J

    2015-01-01

    The phenanthrene skeleton is an important moiety in medical chemistry as it is present in steroidal drugs used as anti-inflammatory and anti-asthmatic agents as well as synthetic hormones or potassium sparing diuretics. Chromatographic properties of 14 derivatives containing the phenanthrene skeleton in their structure with known lipophilicity have been studied. NP, RP, and cyano-bonded silica stationary phases with three binary mobile phases (acetonitrile-water, acetone-water, and acetone-petroleum ether) were tested. Obtained chromatographic data were correlated with the lipophilicity expressed as values of log partition coefficient (P). The presented study was undertaken to find the best TLC system and chromatographic data processing method in order to predict log P values. Correlations between chromatographic data and measurements of lipophilicity of compounds were presented as results of established quantitative structure-retention relationships. Principal component analysis and cluster analysis were used to investigate the similarities among chromatographic systems.

  14. Strain-Field Evaluation of Strain-Relaxed Thin SiGe Layers Fabricated by Ion Implantation Method

    Science.gov (United States)

    Sawano, Kentarou; Ozawa, Yusuke; Fukumoto, Atsushi; Usami, Noritaka; Yamanaka, Junji; Suzuki, Kumiko; Arimoto, Keisuke; Nakagawa, Kiyokazu; Shiraki, Yasuhiro

    2005-10-01

    Strain-relaxed thin SiGe layers grown on ion-implanted Si substrates were evaluated by X-ray diffraction reciprocal space mapping and spatially resolved micro-Raman spectroscopy. It was found that implantation-induced defects effectively facilitated the misfit dislocation generation and multiplication during postannealing after growth, leading to large and homogeneous strain relaxation. While in-plane strain-field fluctuation with crosshatch morphology was clearly observed in the SiGe layer without implantation, a very uniform strain distribution without such morphology was realized in the sample with implantation. These results indicate that the ion implantation method is a very promising approach for realization of high-quality and extremely thin buffer layers.

  15. Electrical isolation of dislocations in Ge layers on Si(001 substrates through CMOS-compatible suspended structures

    Directory of Open Access Journals (Sweden)

    Vishal Ajit Shah, Maksym Myronov, Chalermwat Wongwanitwatana, Lewis Bawden, Martin J Prest, James S Richardson-Bullock, Stephen Rhead, Evan H C Parker, Terrance E Whall and David R Leadley

    2012-01-01

    Full Text Available Suspended crystalline Ge semiconductor structures are created on a Si(001 substrate by a combination of epitaxial growth and simple patterning from the front surface using anisotropic underetching. Geometric definition of the surface Ge layer gives access to a range of crystalline planes that have different etch resistance. The structures are aligned to avoid etch-resistive planes in making the suspended regions and to take advantage of these planes to retain the underlying Si to support the structures. The technique is demonstrated by forming suspended microwires, spiderwebs and van der Pauw cross structures. We finally report on the low-temperature electrical isolation of the undoped Ge layers. This novel isolation method increases the Ge resistivity to 280 Ω cm at 10 K, over two orders of magnitude above that of a bulk Ge on Si(001 layer, by removing material containing the underlying misfit dislocation network that otherwise provides the main source of electrical conduction.

  16. Miniature curved artificial compound eyes.

    Science.gov (United States)

    Floreano, Dario; Pericet-Camara, Ramon; Viollet, Stéphane; Ruffier, Franck; Brückner, Andreas; Leitel, Robert; Buss, Wolfgang; Menouni, Mohsine; Expert, Fabien; Juston, Raphaël; Dobrzynski, Michal Karol; L'Eplattenier, Geraud; Recktenwald, Fabian; Mallot, Hanspeter A; Franceschini, Nicolas

    2013-06-04

    In most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories.

  17. High temperature superconducting compounds

    Science.gov (United States)

    Goldman, Allen M.

    1992-11-01

    The major accomplishment of this grant has been to develop techniques for the in situ preparation of high-Tc superconducting films involving the use of ozone-assisted molecular beam epitaxy. The techniques are generalizable to the growth of trilayer and multilayer structures. Films of both the DyBa2Cu3O(7-x) and YBa2Cu3O(7-x) compounds as well as the La(2-x)Sr(x)CuO4 compound have been grown on the usual substrates, SrTiO3, YSZ, MgO, and LaAlO3, as well as on Si substrates without any buffer layer. A bolometer has been fabricated on a thermally isolated SiN substrate coated with YSZ, an effort carried out in collaboration with Honeywell Inc. The deposition process facilitates the fabrication of very thin and transparent films creating new opportunities for the study of superconductor-insulator transitions and the investigation of photo-doping with carriers of high temperature superconductors. In addition to a thin film technology, a patterning technology has been developed. Trilayer structures have been developed for FET devices and tunneling junctions. Other work includes the measurement of the magnetic properties of bulk single crystal high temperature superconductors, and in collaboration with Argonne National Laboratory, measurement of electric transport properties of T1-based high-Tc films.

  18. Solid-state NMR characterization of the structure and thermal stability of hybrid organic-inorganic compounds based on a HLaNb2O7 Dion-Jacobson layered perovskite.

    Science.gov (United States)

    Cattaneo, Alice S; Ferrara, Chiara; Marculescu, Adriana Mossuto; Giannici, Francesco; Martorana, Antonino; Mustarelli, Piercarlo; Tealdi, Cristina

    2016-08-03

    Dion-Jacobson phases, like MLaNb2O7, are an interesting class of ion-exchangeable layered perovskites possessing electronic and photocatalytic properties. Their protonated and organo-modified homologues, in particular, have already been indicated as promising catalysts. However, the structural analysis of these highly tailorable materials is still incomplete, and both the intercalation process and thermal stability of the included organic moieties are far from being completely understood. In this study, we present a thorough solid-state NMR characterization of HLaNb2O7·xH2O intercalated with different amounts of octylamine, or with decylamine. Samples were analyzed as prepared, and after thermal treatment at different temperatures up to 220 °C. The substitution of pristine proton ions was followed via(1)H MAS NMR spectroscopy, whereas the alkyl chains were monitored through (13)C((1)H) CP MAS experiments. The interactions in the interlayer space were explored using (13)C((1)H) 2D heteronuclear correlation experiments. We demonstrate that some of the protons are involved in the functionalization reaction, and some of them are in close proximity to the alkyl ammonium chains. Heating of the hybrid materials leads first to a rearrangement of the alkyl chains and then to their degradation. The spatial arrangement of the chains, their interactions and the thermal behavior of the materials depend on the extent of the functionalization, and on the nature of the intercalated alkyl ammonium ions.

  19. Organic electronic devices using phthalimide compounds

    Science.gov (United States)

    Hassan, Azad M.; Thompson, Mark E.

    2010-09-07

    Organic electronic devices comprising a phthalimide compound. The phthalimide compounds disclosed herein are electron transporters with large HOMO-LUMO gaps, high triplet energies, large reduction potentials, and/or thermal and chemical stability. As such, these phthalimide compounds are suitable for use in any of various organic electronic devices, such as OLEDs and solar cells. In an OLED, the phthalimide compounds may serve various functions, such as a host in the emissive layer, as a hole blocking material, or as an electron transport material. In a solar cell, the phthalimide compounds may serve various functions, such as an exciton blocking material. Various examples of phthalimide compounds which may be suitable for use in the present invention are disclosed.

  20. Growth of c-plane ZnO on γ-LiAlO{sub 2} (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Yan, T. [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China); Lu, C.-Y.J. [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Schuber, R. [Institute of Applied Physics/DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, DE-76131 Karlsruhe (Germany); Chang, L., E-mail: lwchang@mail.nsysu.edu.tw [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Schaadt, D.M. [Institute of Applied Physics/DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, DE-76131 Karlsruhe (Germany); Institute of Energy Research and Phyiscal Technologies, Clausthal Technical University, Am Stollen 19B, D-38640 Goslar (Germany); Chou, M.M.C.; Ploog, K.H. [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Chiang, C.-M. [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China)

    2015-10-01

    Highlights: • ZnO epilayers were grown on LiAlO{sub 2} (1 0 0) substrate with a GaN buffer layer by MBE. • A high Zn/O flux ratio is beneficial for reducing the density of screw dislocations. • Reciprocal space maps demonstrate that the misfit strain in ZnO has been relaxed. • No interfacial layer is formed at ZnO/GaN interface using a Zn pre-exposure strategy. - Abstract: C-plane ZnO epilayers were grown on LiAlO{sub 2} (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy. Both the X-ray rocking curves and the transmission electron microscopy analyses indicate that the ZnO epilayers exhibit a lower threading dislocation density (∼1 × 10{sup 10} cm{sup −2}) as compared to those grown on LiAlO{sub 2} substrate without the buffer layer. A high Zn/O flux ratio is beneficial for reducing the density of screw-type dislocations. Reciprocal space maps demonstrate that the misfit strain has been relaxed. No interfacial layer is formed at the ZnO/GaN interface by using a Zn pre-exposure strategy. The ZnO epilayers exhibit a strong near band edge emission at 3.28 eV at room temperature with a negligible green band emission.

  1. Regularization strategy for the layered inversion of airborne transient electromagnetic data: application to in-loop data acquired over the basin of Franceville (Gabon)

    Science.gov (United States)

    Guillemoteau, Julien; Sailhac, Pascal; Béhaegel, Mickaël

    2011-11-01

    Airborne transient electromagnetic (TEM) is a cost-effective method to image the distribution of electrical conductivity in the ground. We consider layered earth inversion to interpret large data sets of hundreds of kilometre. Different strategies can be used to solve this inverse problem. This consists in managing the a priori information to avoid the mathematical instability and provide the most plausible model of conductivity in depth. In order to obtain fast and realistic inversion program, we tested three kinds of regularization: two are based on standard Tikhonov procedure which consist in minimizing not only the data misfit function but a balanced optimization function with additional terms constraining the lateral and the vertical smoothness of the conductivity; another kind of regularization is based on reducing the condition number of the kernel by changing the layout of layers before minimizing the data misfit function. Finally, in order to get a more realistic distribution of conductivity, notably by removing negative conductivity values, we suggest an additional recursive filter based upon the inversion of the logarithm of the conductivity. All these methods are tested on synthetic and real data sets. Synthetic data have been calculated by 2.5D modelling; they are used to demonstrate that these methods provide equivalent quality in terms of data misfit and accuracy of the resulting image; the limit essentially comes on special targets with sharp 2D geometries. The real data case is from Helicopter-borne TEM data acquired in the basin of Franceville (Gabon) where borehole conductivity loggings are used to show the good accuracy of the inverted models in most areas, and some biased depths in areas where strong lateral changes may occur.

  2. Small Molecule-Assisted Exfoliation of Layered Zirconium Phosphate Nanoplatelets by Ionic Liquids

    Science.gov (United States)

    Xia, Fangqing; Yong, Huaisong; Han, Xiao; Sun, Dazhi

    2016-07-01

    Exfoliation of layered inorganic nanomaterials into single-layered sheets has been widely interested in materials chemistry and composite fabrication. Here, we report the exfoliation of layered zirconium phosphate nanoplatelets by using small molecule intercalating agents in ionic liquids, which opens a new platform for fabricating single-layered inorganic materials from synthetic layered compounds.

  3. Supermolecular layered dou- ble hydroxides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Research progresses in the layered double hydroxides ·mH2O intercalated with metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are mainly intercalated with polyoxometalate (POM) ions, a LiAl-LDH photochemical assembly containing TiO2 and CH3(CH2)12COO- anions, together with Zn(TPPC) (porphy-rin derivate) and macrocyclic ligand-containing porphyrin derivate anions. Emphasis is put on the synthesis methods for intercalation of the anions into the interlayer regions, the characterization techniques and structures for the layered compounds and the newest research progress in the fields such as catalysis. The review also forecasts the prospects of the field.

  4. Thin layer chromatography.

    Science.gov (United States)

    Santiago, Marina; Strobel, Scott

    2013-01-01

    In many experiments, it is important to be able to separate a mixture into its chemical components in order to isolate one compound or to assess the purity of the mixture. Thin layer chromatography (TLC) is one of the easiest and most versatile methods of doing this because of its low cost, simplicity, quick development time, high sensitivity, and good reproducibility. TLC is used by many industries and fields of research, including pharmaceutical production, clinical analysis, industrial chemistry, environmental toxicology, food chemistry, water, inorganic, and pesticide analysis, dye purity, cosmetics, plant materials, and herbal analysis. In its simplest form, glass plates are coated with a uniform layer of silica gel (SiO2). The dissolved sample is placed on the plate, and the plate is inserted into a screw-top jar containing the developing solvent and a piece of filter paper. When the solvent has risen to near the top of the plate, the plate is removed, dried, and visualized using UV light. Variations on this protocol are used for different purposes, including pretreating the sample, changing the sorbent, plate material, the solvent system, the development techniques, and method of detection and visualization or by coupling TLC to other techniques. © 2013 Elsevier Inc. All rights reserved.

  5. Yield stress of duplex stainless steel specimens estimated using a compound Hall–Petch equation

    Directory of Open Access Journals (Sweden)

    Noriaki Hirota, Fuxing Yin, Tsukasa Azuma and Tadanobu Inoue

    2010-01-01

    Full Text Available In this study, the 0.2% yield stress of duplex stainless steel was evaluated using a compound Hall–Petch equation. The compound Hall–Petch equation was derived from four types of duplex stainless steel, which contained 0.2–64.4 wt% δ-ferrite phase, had different chemical compositions and were annealed at different temperatures. Intragranular yield stress was measured with an ultra-microhardness tester and evaluated with the yield stress model proposed by Dao et al. Grain size, volume fraction and texture were monitored by electron backscattering diffraction measurement. The kγ constant in the compound equation for duplex stainless steel agrees well with that for γ-phase SUS316L steel in the temperature range of 1323–1473 K. The derived compound Hall–Petch equation predicts that the yield stress will be in good agreement with the experimental results for the Cr, Mn, Si, Ni and N solid-solution states. We find that the intragranular yield stress of the δ-phase of duplex stainless steel is rather sensitive to the chemical composition and annealing conditions, which is attributed to the size misfit parameter.

  6. Complex (Mn, X)S compounds-major sites for graphite nucleation in grey cast iron

    Institute of Scientific and Technical Information of China (English)

    Iulian Riposan; Mihai Chisamera; Stelian Stan; Doug White

    2009-01-01

    Despite the cubic system, the ability of sulphides to nucleate graphite can be enhanced by inoculating elements which transform them in complex compounds with a better lattice matching to graphite, a low coagulation capacity, good stability and adequate interracial energy. (Mn,X)S compounds, usually less than 5.0 μm in size, with an average 0.4-2.0 μm well defined core (nucleus), were found to be important sites for graphite nucleation in grey irons. A three-stage model for the nucleation of graphite in grey irons is proposed: (1) Very small micro-inclusions based on strong deoxidizing elements (Mn, Si, Al, Ti, Zr) are formed in the melt; (2) Nucleation of complex (Mn,X)S compounds at these previously formed micro-inclusions; (3) Graphite nucleates on the sides of the (Mn,X)S compounds with lower crystallographic misfit. Al appears to have a key role in this process, as Al contributes to the formation of oxides in the first stage and favors the presence of Sr and Ca in the sulphides, in the second stage. The 0.005-0.010% Al range was found to be beneficial for lower undercooling solidification, type-A graphite formation and carbides avoidance.

  7. Thermally induced strain relaxation in SiGe/Si heterostructures with low-temperature buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, V.I.; Mil' vidskii, M.G. [Institute for Chemical Problems of Microelectronics, 119017 Moscow (Russian Federation); Yugova, T.G. [Institute of Rare Metals ' Giredmet' , 119017 Moscow (Russian Federation); Rzaev, M.M. [Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation); Schaeffler, F. [Institut fuer Halbleiter- und Festkoerperphysik, 4040 Linz (Austria)

    2005-04-01

    Processes of misfit dislocation (MD) nucleation and multiplication in SiGe/Si strained-layer heterostructures under thermal annealing were studied. Specific subjects include the kinetics of dislocation network formation in heterostructures with low-temperature (LT) buffer layers and mechanisms of dislocation nucleation. Samples with LT-Si (400 C) and LT-SiGe (250 C) buffer layers were grown by MBE. In general, the processes of MD generation occur similarly in the heterostructures studied independently of the alloy composition (Ge content: 0.15, 0.30) and kind of buffer layer. Intrinsic point defects related to the LT epitaxial growth influence mainly the rate of MD nucleation. We suggest a new mechanism of MD generation which includes a nucleation of incipient dislocation loops at heterogeneous sources within SiGe epitaxial layer and formation of spiral sources at threading V-shaped dislocation half-loops. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Microscale Group Test for Carbonyl Compounds.

    Science.gov (United States)

    Horak, V.; Klein, R. F. X.

    1985-01-01

    Procedures are provided for a test that (1) demonstrates principles of derivatization with 2,4-dinitrophenylhydrazine; (2) is a thin layer chromatography experiment that visually demonstrates separation of colored compounds of different polarities; and (3) introduces microscale experimentation to students in sophomore organic chemistry…

  9. 十八烷基键合硅胶的原子层沉积法封尾及其在碱性化合物分离中的应用%Endcapping of Octadecyl Bonded Silica by Atomic Layer Deposition for Separation of Basic Compounds

    Institute of Scientific and Technical Information of China (English)

    郭志强; 陈磊; 万谦宏

    2009-01-01

    采用原子层沉积法对十八烷基键合硅胶进行端基封尾.以六甲基二硅氮烷为封端试剂,在250 ℃下与键合硅胶样品反应6 h,制备了对碱性化合物具有高惰性的反相色谱填料.分别以吡啶/苯酚和萘/阿米替林为分子探针,考察了经原子层沉积法和传统液相有机溶剂法封尾处理的十八烷基键合硅胶的色谱性能,并与商品十八烷基硅胶Zorbax SB-C_(18)和Kromasil C_(18)进行对比.结果表明,原子层沉积法封尾的十八烷基硅胶对碱性化合物的分离特性明显优于传统液相法,其色谱性能已超过Zorbax SB-C_(18),与Kromasil C_(18)相当.本方法无需有机溶剂,操作简便,反应耗时短,易于放大生产,封尾反应完全,应用前景良好.%Atomic layer deposition has been employed for postsynthesis treatment of octadecyl bonded silica (ODS) as a typical reversed-phase stationary phase for high performance liquid chromatography (HPLC) ,in an effort to alleviate peak tailing for basic compounds. With hexamethyldisilazane( HMDS) as an endcapping agent,the ODS packing materials were heated to 250℃,and maintained at that temperature for 6 h,affording packing materials which are highly inert to basic compounds. Chromatographic performance in terms of retention factor and tailing factor of the resulting phases was evaluated using phenol/pyridine and naphthalene/ami-triptyline pairs as probes. The results were compared with those for the same packing treated by liquid phase method and for the commercial products including Zorbax SB-C_(18) and Kromasil C_(18). The separation characteristics of the ODS phase obtained by atomic layer deposition appear to be superior to that by liquid phase method and,comparable with or even better than the commercial products studied. Being solvent-free process amenable to mass production,the described method provides an economical and eco-friendly approach to manufacturing HPLC packing materials on industrial scale.

  10. 交变磁场对SHS制备复合钢管陶瓷层相结构的影响%Effects of Alternative Magnetic Field on Phase Structure in Ceramic Layer of Ceramic Lined Compound Steel Pipes Fabricated by SHS

    Institute of Scientific and Technical Information of China (English)

    焦万丽

    2009-01-01

    Effects of alternative magnetic field on phase structure in ceramic layer of ceramic lined compound steel pipes fabricated by SHS were described, and NiO was added as additive to contrast. The results show that change of phase structure in ceramic layer can not be observed in alternative magnetic field. With in-creasing in magnetic flux intensity, size of α-Al2O3 is decreased, and morphology is gradually transformed into fine equiaxed grain structure. Effects of alterna-tive magnetic field are strengthened by adding NiO, which results in the refinement of grain size at a lower magnetic flux density.%将交变磁场引入自蔓延反应,研究其对陶瓷层的相结构的影响,采用NiO作为添加剂进行对比试验.试验结果表明,交变磁场并不改变陶瓷层的相组成.显微结构分析表明,随着磁感应强度的增加,α-AI2O3的枝晶尺寸减小,形态逐渐向细小的等轴晶形态过渡,在磁感应强度为0.2 T时,出现等轴晶组织.NiO的加入增强了交变磁场的影响效果,在NiO加入量为0.4%时可以在0.1 T的磁感应强度下得到细小的等轴晶组织.

  11. Integration of ferroelectric BaTiO3 with Ge: The role of a SrTiO3 buffer layer investigated using aberration-corrected STEM

    Science.gov (United States)

    Wu, HsinWei; Lu, Sirong; Aoki, Toshihiro; Ponath, Patrick; Ekerdt, John G.; Demkov, Alexander A.; McCartney, Martha R.; Smith, David J.

    2017-06-01

    The integration of semiconductors with ferroelectrics having a controlled polarization direction is an ongoing and challenging topic of research. In this work, BaTiO3 (BTO)/SrTiO3 (STO) heterostructures were grown by molecular beam epitaxy either directly with STO substrates or by using 2-nm-thick STO buffer layers on Ge(001) substrates. Sharp, chemically abrupt interfaces and c-axis-oriented BTO films for both types of heterostructures were observed using aberration-corrected scanning transmission electron microscopy and elemental mapping. Anti-phase boundaries as well as ⟨100⟩ misfit dislocations were present in the BTO/STO samples, with the offsets of the dislocation cores varying by distances between 1 and 5 nm away from the BTO/STO interface. Conversely, misfit dislocations were not observed in the BTO/STO/Ge structure although vertical anti-phase boundaries were still common. Overall, the results emphasize the benefits of identifying a suitable buffer layer to ensure the growth of a high quality material having the desired out-of-plane ferroelectric polarization.

  12. Cu2+ in Layered Compounds

    DEFF Research Database (Denmark)

    Aramburu, J. A.; García Lastra, Juan Maria; García-Fernández, P.

    2013-01-01

    been analyzed using a parametrized Jahn–Teller model with an imposed strain [Reinen, D. Inorg. Chem.2012, 51, 4458]. Here, we present results of ab initio periodic supercell and cluster calculations on K2ZnF4:Cu2+, showing unequivocally that the actual origin of the unusual compressed geometry......– distances are, respectively, Rax = 193 pm and Req = 204 pm, and so the calculated distortion Rax – Req = 11 pm is three times smaller than the estimated through the parametrized Jahn–Teller model. As a salient feature, we find that if the CuF64– complex would assume a perfect octahedral geometry (Rax = Req...

  13. Interlayer tunnelling mechanism : experimental test of single layer compounds

    NARCIS (Netherlands)

    Tsvetkov, AA; van der Marel, D; Dulic, D; Molegraaf, HJ; Kolesnikov, NN; Willemsen, B; Ren, ZF; Bozovic,; Pavuna, D

    1998-01-01

    The c-axis optical properties of cuprate superconductors have been studied by grazing angle reflectivity technique. We tested the interlayer tunnelling (ILT) model of high temperature superconductivity and showed that the basic relation between the condensation energy of the superconducting state

  14. High Speed Compound Semiconductor Devices in Layered Structures.

    Science.gov (United States)

    1986-02-25

    Wiegman , Phys. Rev. Letts. 54, 1570 -" (1985). - (3) A.F.J. Levi, J.R. Hayes and P.M. Platzman and W.W,egman, Phys. Rev. Lets. 55, 2071 (1985). (4) 1.R...Hayes, A.F.J. Levi, andW. Wiegman , lectronLett. 20, 851, (1984). (5) S. Muto, K. Imamura, N. Yokoyma, S. Hiyamizu and H. Nishi, Electron Lbtt., 21, 555

  15. Interlayer tunnelling mechanism : experimental test of single layer compounds

    NARCIS (Netherlands)

    Tsvetkov, AA; van der Marel, D; Dulic, D; Molegraaf, HJ; Kolesnikov, NN; Willemsen, B; Ren, ZF; Bozovic,; Pavuna, D

    1998-01-01

    The c-axis optical properties of cuprate superconductors have been studied by grazing angle reflectivity technique. We tested the interlayer tunnelling (ILT) model of high temperature superconductivity and showed that the basic relation between the condensation energy of the superconducting state an

  16. Volatile Organic Compounds (VOCs)

    Science.gov (United States)

    ... Contact Us Share Volatile Organic Compounds' Impact on Indoor Air Quality On this page: Introduction Sources Health Effects Levels in Homes Steps to Reduce Exposure Standards or Guidelines Additional Resources Introduction Volatile organic compounds ( ...

  17. Reissert compound of bisbenzimidazole

    OpenAIRE

    1989-01-01

    A Reissert compound of bisbenzimidazole can be formed by first reacting benzimidazole with an aliphatic diacid chloride to form bisbenzimidazole and then reacting the bisbenzimidazole with an aliphatic acid chloride and cyanide to form the Reissert compound thereof.

  18. Innovation in Layer-by-Layer Assembly.

    Science.gov (United States)

    Richardson, Joseph J; Cui, Jiwei; Björnmalm, Mattias; Braunger, Julia A; Ejima, Hirotaka; Caruso, Frank

    2016-12-14

    Methods for depositing thin films are important in generating functional materials for diverse applications in a wide variety of fields. Over the last half-century, the layer-by-layer assembly of nanoscale films has received intense and growing interest. This has been fueled by innovation in the available materials and assembly technologies, as well as the film-characterization techniques. In this Review, we explore, discuss, and detail innovation in layer-by-layer assembly in terms of past and present developments, and we highlight how these might guide future advances. A particular focus is on conventional and early developments that have only recently regained interest in the layer-by-layer assembly field. We then review unconventional assemblies and approaches that have been gaining popularity, which include inorganic/organic hybrid materials, cells and tissues, and the use of stereocomplexation, patterning, and dip-pen lithography, to name a few. A relatively recent development is the use of layer-by-layer assembly materials and techniques to assemble films in a single continuous step. We name this "quasi"-layer-by-layer assembly and discuss the impacts and innovations surrounding this approach. Finally, the application of characterization methods to monitor and evaluate layer-by-layer assembly is discussed, as innovation in this area is often overlooked but is essential for development of the field. While we intend for this Review to be easily accessible and act as a guide to researchers new to layer-by-layer assembly, we also believe it will provide insight to current researchers in the field and help guide future developments and innovation.

  19. Electrode reactions and electroanalysis of organomercury compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kurmaz, Vladimir A [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation); Gul' tyai, Vadim P [N.D.Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2010-06-09

    Characteristic features of mechanisms and kinetics of electrode reactions of organomercury compounds (symmetrical, non-symmetrical) and organomercury salts on a mercury electrode are analyzed. Attention is focused on the effect of coordination, adsorption and the nature and properties of intermediates on these processes as well as on the formation of organomercury derivatives in the adsorption of organic and hetero-organic compounds on a mercury electrode. The kinetics of heterogeneous chemical equilibrium {sup o}rganic calomel{sup -}symmetrical organomercury compound in the adsorption layer and the relative stability of intermediates in the one-electron reduction of organomercury salts are discussed as well as the electrolytic hydrogen evolution catalyzed by organomercury intermediates. The problems of combined and separate electrochemical quantitation of organic and inorganic mercury compounds in natural objects are considered.

  20. A new layered iron fluorophosphate

    Indian Academy of Sciences (India)

    Amitava Choudhury

    2002-04-01

    A new iron fluorophosphate of the composition, [C6N4H21] [Fe2F2(HPO4)3][H2PO4]·2H2O, I has been prepared by the hydrothermal route. This compound contains iron fluorophosphate layers and the H2PO$_{4}^{-}$ anions are present in the interlayer space along with the protonated amine and water molecules. The compound crystallizes in the monoclinic space group 21/. ( = 13.4422(10) Å, = 9.7320(10) Å, = 18.3123(3) Å, = 92.1480 °, = 2393.92(5) Å3, = 4, = 719.92, calc = 1.997 g cm-3, 1 = 0.03 and 2 = 0.09).

  1. 21 CFR 862.2270 - Thin-layer chromatography system for clinical use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Thin-layer chromatography system for clinical use... Instruments § 862.2270 Thin-layer chromatography system for clinical use. (a) Identification. A thin-layer... a mixture. The mixture of compounds is absorbed onto a stationary phase or thin layer of...

  2. Microscopic physical and chemical properties of graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Eklund, P.C.

    1992-08-24

    Optical spectroscopy (Raman, FTIR and Reflection ) was used to study a variety of acceptor- and donor-type compounds synthesized to determine the microscopic models consistent with the spectrocsopic results. General finding is that the electrical conduction properties of these compounds can be understood on the basis that the intercalation of atomic and/or molecular species between the host graphite layers either raises or lowers the Fermi level (E{sub F)} in a graphitic band structure. This movement of E{sub F} is accomplished via a charge transfer of electrons from the intercalate layers to the graphitic layers (donor compounds), or vice versa (acceptor compounds). Furthermore, the band structure must be modified to take into account the layers of charge that occur as a result of the charge transfer. This charge layering introduces additional bands of states near E{sub F}, which are discussed. Charge-transfer also induces a perturbation of the graphitic normal mode frequencies which can be understood as the result of a contraction (acceptor compounds) or expansion (donor compounds) of the intralayer C-C bonds. Ab-initio calculations support this view and are in reasonable agreement with experimental data.

  3. Ecotoxicology of organofluorous compounds.

    Science.gov (United States)

    Murphy, Margaret B; Loi, Eva I H; Kwok, Karen Y; Lam, Paul K S

    2012-01-01

    Organofluorous compounds have been developed for myriad purposes in a variety of fields, including manufacturing, industry, agriculture, and medicine. The widespread use and application of these compounds has led to increasing concern about their potential ecological toxicity, particularly because of the stability of the C-F bond, which can result in chemical persistence in the environment. This chapter reviews the chemical properties and ecotoxicology of four groups of organofluorous compounds: fluorinated refrigerants and propellants, per- and polyfluorinated compounds (PFCs), fluorinated pesticides, and fluoroquinolone antibiotics. These groups vary in their environmental fate and partitioning, but each raises concern in terms of ecological risk on both the regional and global scale, particularly those compounds with long environmental half-lives. Further research on the occurrence and toxicities of many of these compounds is needed for a more comprehensive understanding of their ecological effects.

  4. TOPICAL REVIEW Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors

    Directory of Open Access Journals (Sweden)

    Tadashi C Ozawa et al

    2008-01-01

    Full Text Available Layered d-metal pnictide oxides are a unique class of compounds which consist of characteristic d-metal pnictide layers and metal oxide layers. More than 100 of these layered compounds, including the recently discovered Fe-based superconducting pnictide oxides, can be classified into nine structure types. These structure types and the chemical and physical properties of the characteristic d-metal pnictide layers and metal oxide layers of the layered d-metal pnictide oxides are reviewed and discussed. Furthermore, possible approaches to design new superconductors based on these layered d-metal pnictide oxides are proposed.

  5. The microstructure and magnetic properties of electrodeposited Co-Pt thin films on Ru buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, G.H. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)], E-mail: skk94@skku.edu; Lee, C.H.; Jang, J.H. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, N.J. [Department of Materials Science and Engineering, Kumoh National University of Technology, Kumi 730-701 (Korea, Republic of); Suh, S.J. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Advanced Materials and Process Research Center for IT, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2008-11-15

    For high-density magnetic recording media, this study examined the crystal structure and the texture of electrodeposited cobalt-platinum (Co-Pt) films on Ru buffer layer. A 15-nm-thick Co-Pt film exhibited very high out-of-plane coercivity and squareness, which were 6248 Oe and 0.89, respectively. The coercivity, H{sub c}, of Co-Pt films grown on Ru buffer layer decreased significantly with increasing thickness, possibly due to the lattice misfit of 5.4% between Co-Pt and Ru, leading to the decrease of perpendicular magnetic anisotropy (PMA) of Co-Pt films as indicated by the observed hexagonal-closed-packed (HCP) (1 1-bar 0 1) plane of Co-Pt films. According to nano beam diffraction pattern (NBDP), however, Co-Pt film grown on Ru layer of HCP exhibited mixed HCP and FCC phases. Also, cross-sectional TEM image suggests that the high PMA may result from the columnar structure of physically isolated Co-Pt grains with the c-axis perpendicular to the film plane.

  6. Double-layered Aurivillius-type ferroelectrics with magnetic moments

    NARCIS (Netherlands)

    Missyul, A. B.; Zvereva, I. A.; Palstra, T. T. M.; Kurbakov, A. I.

    2010-01-01

    We have synthesized the double-layer Aurivillius phase Bi(2)LnNbTiO(9) where Ln = Nd-Gd, Bi. All compounds adopt the orthorhombic polar space group A2(I)am. The magnetic Ln-ion occupies the cuboctahedral position in the middle of the perovskite double-layer, and thus controls the octahedral tilt of

  7. NATURAL POLYACETYLENE COMPOUNDS

    Directory of Open Access Journals (Sweden)

    D. A. Konovalov

    2014-01-01

    Full Text Available Polyacetylenes (polyynes are compounds which contain two or more triple bonds in its structure. About 2 000 different polyacetylenes and biogenetically related substances were identified in 24 families of higher plants. However, most of these compounds were found in seven families of flowering plants: Apiaceae (Umbelliferae, Araliaceae, Asteraceae (Compositae, Campanulaceae, Olacaceae, Pittosporaceae and Santalaceae. Polyacetylenes are relatively unstable, chemically and biologically active compounds, and present in fungi, microorganisms, marine invertebrates and other organisms except for plants. Acetylenes form distinct specialized group of chemically active natural compounds, which are biosynthesized in plants of unsaturated fatty acids. In addition to widespread aliphatic polyacetylenes thiophenes dithiacyclohexadienes (thiarubrines, thioethers, sulphoxides, sulphones, alkamides, chlorohydrins, lactones, spiroacetal enol ethers, furans, pyrans, tetrahydropyrans, isocoumarins, aromatic acetylenes were also found in plant species. Polyacetylenes are localized in different plant organs, and can be found both individually and as a compound with carbohydrates, terpene, phenolic and other compounds. Many polyacetylenes are found in the composition of the essential oils of plants and it confirms their strongly marked ecological functions. From biological point of view these compounds are often synthesized by plants as toxic or bitter antifeedants, allelopathic compounds, phytoalexins or broadly antibiotic components. Polyynes are strong photosensitizers. They exhibit anti-inflammatory, anti-coagulant, anti-bacterial, antituberculosis, anti-fungal, anti-viral, neuroprotective and neurotoxic activity. Immunostimulatory influence associated with certain allergenicity of some of these substances was established. Therefore, without a doubt polyacetylenes are of interest for the modern pharmacy and medicine.

  8. Determination of phenolic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Chao, G.K.J.; Suatoni, J.C.

    1982-01-01

    Details are given of a procedure for separation and identification of phenolic compounds in aqueous solution by high-performance liquid chromatography. It can also be applied to non-aqueous samples after preliminary isolation of a polar fraction containing the phenolic compounds.

  9. Layer-by-layer microcapsules templated on erythrocyte ghost carriers.

    Science.gov (United States)

    Shaillender, Mutukumaraswamy; Luo, Rongcong; Venkatraman, Subbu S; Neu, Björn

    2011-08-30

    This work reports the fabrication of layer-by-layer (LbL) microcapsules that provide a simple mean for controlling the burst and subsequent release of bioactive agents. Red blood cell (RBC) ghosts were loaded with fluorescently labeled dextran and lysozyme as model compounds via hypotonic dialysis with an encapsulation efficiency of 27-31%. It is demonstrated that these vesicles maintain their shape and integrity and that a uniform distribution of the encapsulated agents within these carriers is achieved. The loaded vesicles were then successfully coated with the biocompatible polyelectrolytes, poly-L-arginine hydrochloride and dextran sulfate. It is demonstrated that the release profiles of the encapsulated molecules can be regulated over a wide range by adjusting the number of polyelectrolyte layers. In addition, the LbL shell also protects the RBC ghost from decomposition thereby potentially preserving the bioactivity of encapsulated drugs or proteins. These microcapsules, consisting of an RBC ghost coated with a polyelectrolyte multilayer, provide a simple mean for the preparation of loaded LbL microcapsules eliminating the core dissolution and post-loading of bioactive agents, which are required for conventional LbL microcapsules.

  10. Effect of the Ammonia Flow on the Formation of Microstructure Defects in GaN Layers Grown by High-Temperature Vapor Phase Epitaxy

    Science.gov (United States)

    Barchuk, M.; Lukin, G.; Zimmermann, F.; Röder, C.; Motylenko, M.; Pätzold, O.; Heitmann, J.; Kortus, J.; Rafaja, D.

    2016-12-01

    High-temperature vapor phase epitaxy (HTVPE) is a physical vapor transport technology for a deposition of gallium nitride (GaN) layers. However, little is known about the influence of the deposition parameters on the microstructure of the layers. In order to fill this gap, the influence of the ammonia (NH3) flow applied during the HTVPE growth on the microstructure of the deposited GaN layers is investigated in this work. Although the HTVPE technology is intended to grow GaN layers on foreign substrates, the GaN layers under study were grown on GaN templates produced by metal organic vapor phase epitaxy in order to be able to separate the growth defects from the defects induced by the lattice misfit between the foreign substrate and the GaN layer. The microstructure of the layers is characterized by means of high-resolution x-ray diffraction (XRD), transmission electron microscopy and photoluminescence. In samples deposited at low ammonia flow, planar defects were detected, along which the nitrogen atoms are found to be substituted by impurity atoms. The interplay between these planar defects and the threading dislocations is discussed. A combination of XRD and micro-Raman spectroscopy reveals the presence of compressive residual stress in the samples.

  11. VSWI Wetlands Advisory Layer

    Data.gov (United States)

    Vermont Center for Geographic Information — This dataset represents the DEC Wetlands Program's Advisory layer. This layer makes the most up-to-date, non-jurisdictional, wetlands mapping avaiable to the public...

  12. Basic Ozone Layer Science

    Science.gov (United States)

    Learn about the ozone layer and how human activities deplete it. This page provides information on the chemical processes that lead to ozone layer depletion, and scientists' efforts to understand them.

  13. Ozone Layer Protection

    Science.gov (United States)

    ... Search Search Ozone Layer Protection Share Facebook Twitter Google+ Pinterest Contact Us Ozone Layer Protection Welcome to ... Managing Refrigerant Emissions Stationary Refrigeration and Air Conditioning Car and Other Mobile Air Conditioning GreenChill Partnership Responsible ...

  14. 反相薄层色谱法测定1-1,2,4-三唑类杀菌剂的疏水性%Lipophilicity Determination of Some 1-1, 2, 4-Triazole Compounds by Reversed-phase Thin Layer Chromatography

    Institute of Scientific and Technical Information of China (English)

    江正瑾; 张智超; 尹标林; 赵国峰; 王琴孙

    2001-01-01

    A study has been carried out of evaluating lipophilicity of some 1-1, 2, 4-triazole compounds by RP-HPTLC. An equation that reasonably correlates partition coefficients(clgP) with RM0 values for 23 1-1,2,4-triazole compounds was derived and its predictive capability was tested with five 1-1,2,4-triazole compounds. It has been found that RP-HPTLC can be extensively applied to determining lipophilicity of 1-1,2,4-triazole compounds.

  15. MEA 86 Compound data

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data file contains the full raw parameter data for the 86 compounds tested in the developmental MEA assay, as well as Area Under the Curve (AUC) calculations...

  16. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  17. Heart testing compound

    Science.gov (United States)

    Knapp, F.F. Jr.; Goodman, M.M.

    1983-06-29

    The compound 15-(p-(/sup 125/I)-iodophenyl)-6-tellurapentadecanoic acid is disclosed as a myocardial imaging agent having rapid and pronounced uptake, prolonged myocardial retention, and low in vivo deiodination.

  18. Polynitramino compounds outperform PETN.

    Science.gov (United States)

    Joo, Young-Hyuk; Shreeve, Jean'ne M

    2010-01-07

    New polynitramino compounds were synthesized and fully characterized using IR and multinuclear ((1)H, (13)C, (15)N) NMR spectroscopy, and elemental analysis as well as single-crystal X-ray diffraction.

  19. Thermodynamics of Organic Compounds

    Science.gov (United States)

    1979-01-01

    General Techniques for Combustion of Liquid/Soli. Organic Compounds by Oxygen Bomb Calorimetry by Arthur J. Head, William D. Good, and Ccrnelius...Mosselman, Chap. 8; Combustion of Liquid/Solid Organic Compounds with Non-Metallic Hetero-Atoms by Arthur J. Head and William D. Good, Chap. 9; in...0 Box 95085 Washington, DC 20234 Los Angeles, CA 90045 National Bureau of Standards CINDAS Chemical Thermodynamics Division Purdue University

  20. Compound composite odontoma.

    Science.gov (United States)

    Girish, G; Bavle, Radhika M; Singh, Manish Kumar; Prasad, Sahana N

    2016-01-01

    The term odontoma has been used as a descriptor for any tumor of odontogenic origin. It is a growth in which both epithelial and mesenchymal cells exhibits complete differentiation. Odontomas are considered as hamartomas rather than true neoplasm. They are usually discovered on routine radiographic examination. Odontomas, according to the World Health Organization, are classified into complex odontoma and compound odontomas. The present paper reports a case of compound composite odontomas.

  1. Compound composite odontoma

    Directory of Open Access Journals (Sweden)

    G Girish

    2016-01-01

    Full Text Available The term odontoma has been used as a descriptor for any tumor of odontogenic origin. It is a growth in which both epithelial and mesenchymal cells exhibits complete differentiation. Odontomas are considered as hamartomas rather than true neoplasm. They are usually discovered on routine radiographic examination. Odontomas, according to the World Health Organization, are classified into complex odontoma and compound odontomas. The present paper reports a case of compound composite odontomas.

  2. Chemistry of peroxide compounds

    Science.gov (United States)

    Volnov, I. I.

    1981-01-01

    The history of Soviet research from 1866 to 1967 on peroxide compounds is reviewed. This research dealt mainly with peroxide kinetics, reactivity and characteristics, peroxide production processes, and more recently with superoxides and ozonides and emphasis on the higher oxides of group 1 and 2 elements. Solid state fluidized bed synthesis and production of high purity products based on the relative solubilities of the initial, intermediate, and final compounds and elements in liquid ammonia are discussed.

  3. Phenolic Molding Compounds

    Science.gov (United States)

    Koizumi, Koji; Charles, Ted; de Keyser, Hendrik

    Phenolic Molding Compounds continue to exhibit well balanced properties such as heat resistance, chemical resistance, dimensional stability, and creep resistance. They are widely applied in electrical, appliance, small engine, commutator, and automotive applications. As the focus of the automotive industry is weight reduction for greater fuel efficiency, phenolic molding compounds become appealing alternatives to metals. Current market volumes and trends, formulation components and its impact on properties, and a review of common manufacturing methods are presented. Molding processes as well as unique advanced techniques such as high temperature molding, live sprue, and injection/compression technique provide additional benefits in improving the performance characterisitics of phenolic molding compounds. Of special interest are descriptions of some of the latest innovations in automotive components, such as the phenolic intake manifold and valve block for dual clutch transmissions. The chapter also characterizes the most recent developments in new materials, including long glass phenolic molding compounds and carbon fiber reinforced phenolic molding compounds exhibiting a 10-20-fold increase in Charpy impact strength when compared to short fiber filled materials. The role of fatigue testing and fatigue fracture behavior presents some insight into long-term reliability and durability of glass-filled phenolic molding compounds. A section on new technology outlines the important factors to consider in modeling phenolic parts by finite element analysis and flow simulation.

  4. Multilayer Article Characterized by Low Coefficient of Thermal Expansion Outer Layer

    Science.gov (United States)

    Lee, Kang N. (Inventor)

    2004-01-01

    A multilayer article comprises a substrate comprising a ceramic or a silicon-containing metal alloy. The ceramic is a Si-containing ceramic or an oxide ceramic with or without silicon. An outer layer overlies the substrate and at least one intermediate layer is located between the outer layer and thc substrate. An optional bond layer is disposed between thc 1 least one intermediate layer and thc substrate. The at least one intermediate layer may comprise an optional chemical barrier layer adjacent the outer layer, a mullite-containing layer and an optional chemical barrier layer adjacent to the bond layer or substrate. The outer layer comprises a compound having a low coefficient of thermal expansion selected from one of the following systems: rare earth (RE) silicates; at least one of hafnia and hafnia-containing composite oxides; zirconia-containing composite oxides and combinations thereof.

  5. Highly trifluoromethylated platinum compounds.

    Science.gov (United States)

    Martínez-Salvador, Sonia; Forniés, Juan; Martín, Antonio; Menjón, Babil

    2011-07-11

    The homoleptic, square-planar organoplatinum(II) compound [NBu(4)](2) [Pt(CF(3))(4)] (1) undergoes oxidative addition of CF(3) I under mild conditions to give rise to the octahedral organoplatinum(IV) complex [NBu(4)](2) [Pt(CF(3))(5)I] (2). This highly trifluoromethylated species reacts with Ag(+) salts of weakly coordinating anions in Me(2)CO under a wet-air stream to afford the aquo derivative [NBu(4)][Pt(CF(3))(5) (OH(2))] (4) in around 75% yield. When the reaction of 2 with the same Ag(+) salts is carried out in MeCN, the solvento compound [NBu(4) ][Pt(CF(3))(5)(NCMe)] (5) is obtained in around 80% yield. The aquo ligand in 4 as well as the MeCN ligand in 5 are labile and can be cleanly replaced by neutral and anionic ligands to furnish a series of pentakis(trifluoromethyl)platinate(IV) compounds with formulae [NBu(4)][Pt(CF(3))(5) (L)] (L=CO (6), pyridine (py; 7), tetrahydrothiophene (tht; 8)) and [NBu(4)](2) [Pt(CF(3))(5)X] (X=Cl (9), Br (10)). The unusual carbonyl-platinum(IV) derivative [NBu(4)][Pt(CF(3))(5) (CO)] (6) is thermally stable and has a ν(CO) of 2194 cm(-1). The crystal structures of 2⋅CH(2)Cl(2), 5, [PPh(4) ][Pt(CF(3))(5)(CO)] (6'), and 7 have been established by X-ray diffraction methods. Compound 2 has shown itself to be a convenient entry to the chemistry of highly trifluoromethylated platinum compounds. To the best of our knowledge, compounds 2 and 4-10 are the organoelement compounds with the highest CF(3) content to have been isolated and adequately characterized to date.

  6. Piezoelectric Resonator with Two Layers

    Science.gov (United States)

    Stephanou, Philip J. (Inventor); Black, Justin P. (Inventor)

    2013-01-01

    A piezoelectric resonator device includes: a top electrode layer with a patterned structure, a top piezoelectric layer adjacent to the top layer, a middle metal layer adjacent to the top piezoelectric layer opposite the top layer, a bottom piezoelectric layer adjacent to the middle layer opposite the top piezoelectric layer, and a bottom electrode layer with a patterned structure and adjacent to the bottom piezoelectric layer opposite the middle layer. The top layer includes a first plurality of electrodes inter-digitated with a second plurality of electrodes. A first one of the electrodes in the top layer and a first one of the electrodes in the bottom layer are coupled to a first contact, and a second one of the electrodes in the top layer and a second one of the electrodes in the bottom layer are coupled to a second contact.

  7. Conduction band offset determination between strained CdSe and ZnSe layers using DLTS

    Science.gov (United States)

    Rangel-Kuoppa, Victor-Tapio

    2013-12-01

    The conduction band offset between strained CdSe layers embedded in unintentionally n-type doped ZnSe is measured and reported. Two samples, consisting of thirty Ultra Thin Quantum Wells (UTQWs) of CdSe embedded in ZnSe, grown by Atomic Layer Epitaxy, are used for this study. The thicknesses of the UTQWs are one and three monolayers (MLs) in each sample, respectively. As expected, the sample with one ML UTQWs does not show any energy level in the UTQWs due to the small thickness of the UTQWs, while the thickness of the sample with 3 ML UTQWs is large enough to form an energy level inside the UTQWs. This energy level appears as a majority trap with an activation energy of 223.58 ± 9.54 meV. This corresponds to UTQWs with barrier heights (the conduction band offset) between 742 meV and 784 meV. These values suggest that the band gap misfit between strained CdSe and ZnSe is around 70.5 to 74 % in the conduction band.

  8. Conduction band offset determination between strained CdSe and ZnSe layers using DLTS

    Energy Technology Data Exchange (ETDEWEB)

    Rangel-Kuoppa, Victor-Tapio [Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, A-4040 Linz (Austria)

    2013-12-04

    The conduction band offset between strained CdSe layers embedded in unintentionally n-type doped ZnSe is measured and reported. Two samples, consisting of thirty Ultra Thin Quantum Wells (UTQWs) of CdSe embedded in ZnSe, grown by Atomic Layer Epitaxy, are used for this study. The thicknesses of the UTQWs are one and three monolayers (MLs) in each sample, respectively. As expected, the sample with one ML UTQWs does not show any energy level in the UTQWs due to the small thickness of the UTQWs, while the thickness of the sample with 3 ML UTQWs is large enough to form an energy level inside the UTQWs. This energy level appears as a majority trap with an activation energy of 223.58 ± 9.54 meV. This corresponds to UTQWs with barrier heights (the conduction band offset) between 742 meV and 784 meV. These values suggest that the band gap misfit between strained CdSe and ZnSe is around 70.5 to 74 % in the conduction band.

  9. Nomenclature of chemical compounds

    Directory of Open Access Journals (Sweden)

    Karolina Kaczmarek

    2009-01-01

    Full Text Available This article presents the mechanisms of the inorganic chemistry nomenclature formation in French language. It shows the structure and the way of presenting the names of chemical compounds either descriptively or by giving the structural formulas’ characteristics, their transcription and order of reading the letters. The text specifies the rules of naming a chemical compound, according to the criteria of IUPAC (Union of Pure and Applied Chemistry, the organisation responsible for digesting the chemical nomenclature. The article contains the transcription chart and the manner of reading the structural formula, also called latero-numerical. Additionally, there is information conceming the usage of the common names given, still remaining in use next to the names compatible with those of IUPAC. Particular types of chemical compounds have served as models for description of other nomenclature formation rules from the simplest structures to the complicated compound ones. A short summary presents the relations and similarities between the names of particular types of chemical compounds.

  10. Building biomedical materials layer-by-layer

    Directory of Open Access Journals (Sweden)

    Paula T. Hammond

    2012-05-01

    Full Text Available In this materials perspective, the promise of water based layer-by-layer (LbL assembly as a means of generating drug-releasing surfaces for biomedical applications, from small molecule therapeutics to biologic drugs and nucleic acids, is examined. Specific advantages of the use of LbL assembly versus traditional polymeric blend encapsulation are discussed. Examples are provided to present potential new directions. Translational opportunities are discussed to examine the impact and potential for true biomedical translation using rapid assembly methods, and applications are discussed with high need and medical return.

  11. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  12. Low Temperature Structure and Properties of Graphite Lamellar Compounds.

    Science.gov (United States)

    1984-01-01

    macroscopic defects hinder crystallographic analyses : the lack of layer planeness (e.g., puckering of the layers) and the presence of twinned...between these two and it seams that at 300 K, the 2D melting process has already started for the three compounds. As concerns n, its value is much...free metal and that of graphite; for the others, this value is smaller than both of these. It seams then, a priori, difficult to interpret this expansion

  13. Extended defects in 4H-silicon carbide homoepitaxial layers

    Science.gov (United States)

    Zhang, Xuan

    The purpose of this thesis is to study the structure of extended defects in 4H-SIC homoepitaxial layers, and to identify their nucleation mechanisms. Characteristics of basal plane dislocations in 4H-SiC epilayers were investigated in a comprehensive manner, including their morphologies, Burgers' vectors, positions, and correlation with the extended defects propagating from the substrate. Plan-view transmission x-ray topography was the major characterization technique used in this study. Complementary data was obtained by KOH etching and optical microscopy. Trace of glide was detected on every basal plane dislocation in the entire 3-inch epilayer. In the center area of the epi-wafer, the glide can extend to macroscopic distance and form edge-type dislocations at the epilayer/surface interface. During the motion, dislocation half loop arrays were found to nucleate at the growth front. The magnitude of the resolved shear stress was estimated based on the radius of curvature of the dislocation lines. It surpassed the critical resolved shear stress at the epitaxial growth temperature. The stress was identified to be compressive in the epilayer. Its origin was studied. Nitrogen-doping-difference-induced misfit strain was excluded as the source of the stress. The structures of two morphological defects, 'carrots' and 'arrows', were studied. Cross-section x-ray topography was used to image the structure of carrot defect in whole. The defect was found to nucleate at the epilayer/substrate interface on a threading screw dislocation propagating from the substrate. Its structure was mainly composed of a prismatic stacking fault and a Frank-type basal plane stacking fault. The arrow defect was found to be produced by a spheroid shape inclusion in the volume of the epilayer. Zone axis diffraction pattern under transmission electron microscope identified the nature of the inclusion as 3C-SIC. It was determined to nucleate at the substrate surface contaminations.

  14. Flavour Compounds in Fungi

    DEFF Research Database (Denmark)

    Ravasio, Davide Antonio

    Fungi produce a variety of volatile organic compounds (VOCs) during their primary or secondary metabolism and with a wide range of functions. The main focus of this research work has been put on flavour molecules that are produced during fermentation processes, mainly esters and alcohols derived...... region is directly regulated by the ScAro80 transcription factor. This interaction has been used to create a lacZ-reporter system to correlate the formation of two volatile compounds, 2- phenylethanol and 2-phenylethyl acetate in yeast with ARO9 expression levels. This indirect genetic assay also....... This resulted in the identification of Wickerhamomyces anomalus and Pichia kluyveri as high producers of esters fruity compounds, which contribute to enhance the complexity of wine and beer product. In addition the strain Debaromyces subglobosus showed high yields of aldehydes and fruity ketones, which...

  15. Layered Atom Arrangements in Complex Materials

    Energy Technology Data Exchange (ETDEWEB)

    K.E. Sikafus; R.W.Grimes; S.M.Corish; A.R. Cleave; M.Tang; C.R.Stanek; B.P. Uberuaga; J.A.Valdez

    2005-04-15

    In this report, we develop an atom layer stacking model to describe systematically the crystal structures of complex materials. To illustrate the concepts, we consider a sequence of oxide compounds in which the metal cations progress in oxidation state from monovalent (M{sup 1+}) to tetravalent (M{sup 4+}). We use concepts relating to geometric subdivisions of a triangular atom net to describe the layered atom patterns in these compounds (concepts originally proposed by Shuichi Iida). We demonstrate that as a function of increasing oxidation state (from M{sup 1+} to M{sup 4+}), the layer stacking motifs used to generate each successive structure (specifically, motifs along a 3 symmetry axis), progress through the following sequence: MMO, MO, M{sub r}O, MO{sub r/s}O{sub u/v}, MOO (where M and O represent fully dense triangular atom nets and r/s and u/v are fractions used to describe partially filled triangular atom nets). We also develop complete crystallographic descriptions for the compounds in our oxidation sequence using trigonal space group R{bar 3}.

  16. Methods for fabricating thin film III-V compound solar cell

    Science.gov (United States)

    Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

    2011-08-09

    The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

  17. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip

    2013-01-01

    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  18. Misfits in Skyrme-Hartree-Fock

    CERN Document Server

    Erler, J; Reinhard, P -G

    2010-01-01

    We address very briefly five critical points in the context of the Skyrme-Hartree-Fock (SHF) scheme: 1) the impossibility to consider it as an interaction, 2) a possible inconsistency of correlation corrections as, e.g., the center-of-mass correction, 3) problems to describe the giant dipole resonance (GDR) simultaneously in light and heavy nuclei, 4) deficiencies in the extrapolation of binding energies to super-heavy elements (SHE), and 5) a yet inappropriate trend in fission life-times when going to the heaviest SHE. While the first two points have more a formal bias, the other three points have practical implications and wait for solution.

  19. Evolution: The Island of Misfit Mammoths.

    Science.gov (United States)

    Roca, Alfred L

    2015-06-29

    The genomes of two woolly mammoths have been sequenced. One of the last survivors had reduced genetic diversity. Although divergent in their mitochondrial genomes, the mammoths had similar nuclear genomes, a finding germane to elephant conservation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cariou, R., E-mail: romain.cariou@polytechnique.edu [LPICM-CNRS, Ecole Polytechnique, 91128, Palaiseau (France); III-V lab a joint laboratory between Alcatel-Lucent Bell Labs France, Thales Research and Technology and CEA-LETI, route de Nozay, 91460, Marcoussis, France. (France); Ruggeri, R. [LPICM-CNRS, Ecole Polytechnique, 91128, Palaiseau (France); CNR-IMM, strada VIII n°5, zona industriale, 95121, Catania (Italy); Tan, X.; Nassar, J.; Roca i Cabarrocas, P. [LPICM-CNRS, Ecole Polytechnique, 91128, Palaiseau (France); Mannino, Giovanni [CNR-IMM, strada VIII n°5, zona industriale, 95121, Catania (Italy)

    2014-07-15

    We report on unusual low temperature (175 °C) heteroepitaxial growth of germanium thin films using a standard radio-frequency plasma process. Spectroscopic ellipsometry and transmission electron microscopy (TEM) reveal a perfect crystalline quality of epitaxial germanium layers on (100) c-Ge wafers. In addition direct germanium crystal growth is achieved on (100) c-Si, despite 4.2% lattice mismatch. Defects rising from Ge/Si interface are mostly located within the first tens of nanometers, and threading dislocation density (TDD) values as low as 10{sup 6} cm{sup −2} are obtained. Misfit stress is released fast: residual strain of −0.4% is calculated from Moiré pattern analysis. Moreover we demonstrate a striking feature of low temperature plasma epitaxy, namely the fact that crystalline quality improves with thickness without epitaxy breakdown, as shown by TEM and depth profiling of surface TDD.

  1. Aminopropyl thiophene compounds

    Science.gov (United States)

    Goodman, Mark M.; Knapp, Jr., Furn F.

    1990-01-01

    Radiopharmaceuticals useful in brain imaging comprising radiohalogenated thienylethylamine derivatives. The compounds are 5-halo-thiophene-2-isopropyl amines able to cross the blood-brain barrier and be retained for a sufficient length of time to allow the evaluation of regional blood flow by radioimaging of the brain.

  2. Toxicology of perfluorinated compounds

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, Thorsten [Hessian State Laboratory, Wiesbaden (Germany); Mattern, Daniela; Brunn, Hubertus [Hessian State Laboratory, Giessen (Germany)

    2011-12-15

    Perfluorinated compounds [PFCs] have found a wide use in industrial products and processes and in a vast array of consumer products. PFCs are molecules made up of carbon chains to which fluorine atoms are bound. Due to the strength of the carbon/fluorine bond, the molecules are chemically very stable and are highly resistant to biological degradation; therefore, they belong to a class of compounds that tend to persist in the environment. These compounds can bioaccumulate and also undergo biomagnification. Within the class of PFC chemicals, perfluorooctanoic acid and perfluorosulphonic acid are generally considered reference substances. Meanwhile, PFCs can be detected almost ubiquitously, e.g., in water, plants, different kinds of foodstuffs, in animals such as fish, birds, in mammals, as well as in human breast milk and blood. PFCs are proposed as a new class of 'persistent organic pollutants'. Numerous publications allude to the negative effects of PFCs on human health. The following review describes both external and internal exposures to PFCs, the toxicokinetics (uptake, distribution, metabolism, excretion), and the toxicodynamics (acute toxicity, subacute and subchronic toxicities, chronic toxicity including carcinogenesis, genotoxicity and epigenetic effects, reproductive and developmental toxicities, neurotoxicity, effects on the endocrine system, immunotoxicity and potential modes of action, combinational effects, and epidemiological studies on perfluorinated compounds). (orig.)

  3. NATURAL POLYACETYLENE COMPOUNDS

    Directory of Open Access Journals (Sweden)

    A. M. Nasukhova

    2014-01-01

    Full Text Available In article the review of the initial stage of researches of natural polyacetylene compounds is resulted. The high reactionary ability leading to fast oxidation and degradation of these compounds, especially at influence of Uf-light, oxygen of air, pH and other factors, has caused the serious difficulties connected with an establishment of structure and studying of their physical and chemical properties. Therefore the greatest quantity of works of this stage is connected with studying of essential oils of plants from families Apiaceae, Araliaceae, Asteraceae, Campanulaceae, Olacaceae, Pittosporaceae and Santalaceae where have been found out, basically, diacetylene compounds. About development of physical and chemical methods of the analysis of possibility of similar researches have considerably extended. More than 2000 polyacetylenes are known today, from them more than 1100 are found out in plants fam. Asteraceae. Revolution in the field of molecular biology has allowed to study processes of biosynthesis of these compounds intensively.

  4. Computing compound distributions faster

    NARCIS (Netherlands)

    P. den Iseger; M.A.J. Smith; R. Dekker (Rommert)

    1997-01-01

    textabstractThe use of Panjer's algorithm has meanwhile become a widespread standard technique for actuaries (Kuon et al., 1955). Panjer's recursion formula is used for the evaluation of compound distributions and can be applied to life and general insurance problems. The discrete version of Panjer'

  5. Flavour Compounds in Fungi

    DEFF Research Database (Denmark)

    Ravasio, Davide Antonio

    Fungi produce a variety of volatile organic compounds (VOCs) during their primary or secondary metabolism and with a wide range of functions. The main focus of this research work has been put on flavour molecules that are produced during fermentation processes, mainly esters and alcohols derived...

  6. Fun with Ionic Compounds

    Science.gov (United States)

    Logerwell, Mollianne G.; Sterling, Donna R.

    2007-01-01

    Ionic bonding is a fundamental topic in high school chemistry, yet it continues to be a concept that students struggle to understand. Even if they understand atomic structure and ion formation, it can be difficult for students to visualize how ions fit together to form compounds. This article describes several engaging activities that help…

  7. Growth of semipolar (1\\bar{1}01) high-indium-content InGaN quantum wells using InGaN tilting layer on Si(001)

    Science.gov (United States)

    Kushimoto, Maki; Honda, Yoshio; Amano, Hiroshi

    2016-05-01

    Low-toxity high-In-content InGaN is an attractive option for short-distance communications through plastic optical fibers because its performance is only slightly affected by temperature. However, its fabrication on the c-plane is impaired by In droplets and V pits, which form at low-growth temperature. On the other hand, unlike the c-plane, (1\\bar{1}01) InGaN relaxes with tilting. Therefore, in this study, we first grew a high-In-content InGaN single layer, and then we fabricated an InGaN tilting layer between (1\\bar{1}01) InGaN-based multiple quantum wells (MQWs) and GaN stripes/(001)Si. The emission wavelength increased with the InGaN tilting layer’s growth time because the strain was relaxed by misfit dislocations at the heterointerface. This layer also extended the emission peak of InGaN/GaN MQWs and increased the photoluminescence intensity with respect to that of a single-layered InGaN. Therefore, the InGaN tilting layer is effective for growing high-In-content (1\\bar{1}01) InGaN MQWs.

  8. Impact of high-temperature annealing of AlN layer on sapphire and its thermodynamic principle

    Science.gov (United States)

    Fukuyama, Hiroyuki; Miyake, Hideto; Nishio, Gou; Suzuki, Shuhei; Hiramatsu, Kazumasa

    2016-05-01

    The N2-CO gas annealing technique was demonstrated to improve the crystalline quality of the AlN layer on sapphire. 300-nm-thick AlN layers were fabricated on sapphire substrates by a metal-organic vapor phase epitaxy method. The AlN layers were annealed in N2 and/or N2-CO gas atmosphere at 1923-1973 K for 0.5-4 h. Many pits and voids were observed on the AlN surface annealed in N2 atmosphere at 1973 K for 2 h. The rough surface was, however, much improved for the AlN annealed in N2-CO gas atmosphere. The thermodynamic principle of the N2-CO gas annealing technique is explained in this paper on the basis of the phase stability diagram of the Al2O3-AlN-C-N2-CO system. Voids and γ-aluminum oxynitride (γ-AlON) at the AlN/sapphire interface formed during the annealing, which is also explained on the basis of the phase stability diagram. The in-plane epitaxial relationships among AlN, γ-AlON, and sapphire are presented, and misfits among them are discussed.

  9. Toxicity of dipyridyl compounds and related compounds.

    Science.gov (United States)

    Li, Shenggang; Crooks, Peter A; Wei, Xiaochen; de Leon, Jose

    2004-01-01

    Five dipyridyl isomers, 2,2'-, 2,3'-, 2,4'-, 3,3'-, and 4,4'-dipyridyl, are products resulting from the pyrolytic degradation of tobacco products and degradation of the herbicide paraquat, and therefore may be present in the environment. In this article, the toxicological properties of these dipyridyl isomers in humans and animals are reviewed. Epidemiological studies suggest that cancerous skin lesions in workers involved in the manufacturing of paraquat may be associated with exposure to dipyridyl compounds. Experimental animal studies suggest that dipyridyl isomers may have several toxicological effects. Three of the dipyridyl isomers (the 2,2', 2,4', and 4,4' isomers) appear to be inducers of some metabolic enzymes. The 2,2'-dipyridyl isomer, an iron chelator, appears to influence vasospasm in primate models of stroke. The cytotoxic effects of 2,2'-dipyridyl on several leukemia cell lines have been reported, and a potent teratogenic effect of 2,2'-dipyridyl has been observed in rats. Based on the results of paraquat studies in experimental animal models, it has been proposed that paraquat may have deleterious effects on dopaminergic neurons. These findings support the epidemiological evidence that paraquat exposure may be associated with the development of Parkinson's disease. Studies designed to determine an association between paraquat exposure and Parkinson's disease are complicated by the possibility that metabolic changes may influence the neurotoxicity of paraquat and/or its metabolites. Preliminary unpublished data in mice show that 300-mg/kg doses of 2,2'-dipyridyl are neurotoxic, and 300-mg/kg doses of 2,4'- and 4,4'-dipyridyls are lethal. These results are consistent with earlier studies in Sherman rats using high 2,2'- and 4,4'-dipyridyl doses. New studies are needed to further explore the toxicological properties of dipyridyls and their potential public health impact.

  10. Process for forming a metal compound coating on a substrate

    Science.gov (United States)

    Sharp, D.J.; Vernon, M.E.; Wright, S.A.

    1988-06-29

    A method of coating a substrate with a thin layer of a metal compound by forming a dispersion of an electrophoretically active organic colloid and a precursor of the metal compound in an electrolytic cell in which the substrate is an electrode. Upon application of an electric potential, the electrode is coated with a mixture of the organic colloid and the precursor to the metal compound, and the coated substrate is then heated in the presence of an atmosphere or vacuum to decompose the organic colloid and form a coating of either a combination of metal compound and carbon, or optionally forming a porous metal compound coating by heating to a temperature high enough to chemically react the carbon.

  11. The Equatorial Ekman Layer

    CERN Document Server

    Marcotte, Florence; Soward, Andrew

    2016-01-01

    The steady incompressible viscous flow in the wide gap between spheres rotating about a common axis at slightly different rates (small Ekman number E) has a long and celebrated history. The problem is relevant to the dynamics of geophysical and planetary core flows, for which, in the case of electrically conducting fluids, the possible operation of a dynamo is of considerable interest. A comprehensive asymptotic study, in the limit E<<1, was undertaken by Stewartson (J. Fluid Mech. 1966, vol. 26, pp. 131-144). The mainstream flow, exterior to the E^{1/2} Ekman layers on the inner/outer boundaries and the shear layer on the inner sphere tangent cylinder C, is geostrophic. Stewartson identified a complicated nested layer structure on C, which comprises relatively thick quasi-geostrophic E^{2/7} (inside C) and E^{1/4} (outside C) layers. They embed a thinner E^{1/3} ageostrophic shear layer (on C), which merges with the inner sphere Ekman layer to form the E^{2/5} Equatorial Ekman layer of axial length E^{...

  12. The Application of Layer Theory to Design: The Control Layer

    Science.gov (United States)

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  13. Erupted compound odontome

    Directory of Open Access Journals (Sweden)

    Shekar S

    2009-01-01

    Full Text Available Odontomas are considered to be hamartomas rather than a true neoplasm. They consist chiefly of enamel and dentin, with variable amount of pulp and cementum when fully developed. They are generally asymptomatic and are included under the benign calcified odontogenic tumors. They are usually discovered on routine radiographic examination. Eruption of an odontoma in the oral cavity is rare. Peripheral compound odontomas arise extraosseously and have a tendency to exfoliate. In this article we are reporting a case of a 15-year-old girl with peripheral compound odontoma, with a single rudimentary tooth-like structure in the mandibular right second molar region, which is about to be exfoliated. Its eruption in the oral cavity and location in the mandibular posterior region is associated with aplasia of the mandibular right second molar, making it an interesting case for reporting.

  14. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert

    1993-01-01

    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  15. Multi-layer coatings

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoodi, Sina; Brophy, Brenor L.; Abrams, Ze' ev R.; Gonsalves, Peter R.

    2016-06-28

    Disclosed herein are coating materials and methods for applying a top-layer coating that is durable, abrasion resistant, highly transparent, hydrophobic, low-friction, moisture-sealing, anti-soiling, and self-cleaning to an existing conventional high temperature anti-reflective coating. The top coat imparts superior durability performance and new properties to the under-laying conventional high temperature anti-reflective coating without reducing the anti-reflectiveness of the coating. Methods and data for optimizing the relative thickness of the under-layer high temperature anti-reflective coating and the top-layer thickness for optimizing optical performance are also disclosed.

  16. Process for compound transformation

    KAUST Repository

    Basset, Jean-Marie

    2016-12-29

    Embodiments of the present disclosure provide for methods of using a catalytic system to chemically transform a compound (e.g., a hydrocarbon). In an embodiment, the method does not employ grafting the catalyst prior to catalysis. In particular, embodiments of the present disclosure provide for a process of hydrocarbon (e.g., C1 to C20 hydrocarbon) metathesis (e.g., alkane, olefin, or alkyne metathesis) transformation, where the process can be conducted without employing grafting prior to catalysis.

  17. Biodegradation of Organofluorine Compounds

    Science.gov (United States)

    2016-02-01

    RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) XX-02-2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) Mar 2011 – Sep...compounds as sole carbon sources for growth, which was confirmed on two substrates: benzoyl fluoride and 1H,1H,2H,2H-perfluorooctyltriethoxysilane...Subsequent measurements of defluorination rates showed that benzoyl fluoride defluorinated very rapidly; therefore, the growth observed was probably

  18. Novel electrochemical sensors with electrodes based on multilayers fabricated by layer-by-layer synthesis and their analytical potential

    Science.gov (United States)

    Ermakov, S. S.; Nikolaev, K. G.; Tolstoy, V. P.

    2016-08-01

    The results of studies on layer-by-layer synthesis of multilayers on the electrode surface in order to design electrochemical sensors for the determination of concentrations of inorganic, organic and bioorganic compounds are summarized and analyzed. The principle of the method is discoursed and the key advantages of the approach are highlighted, such as the possibility of single layer synthesis with specified thickness and composition under mild conditions with further fabrication of multilayers. Charge transfer conditions in the layers on the electrode surface between the analyte molecules and electrode redox centres and the operating conditions for the optimal electrode are considered. The role of electrocatalysts and intermediates of these processes is noted. Particular attention is devoted to the methods for synthesis of gold nanoparticles with different diameters. Analytical characteristics for electrochemical sensors are presented and application prospects of the layer-by-layer synthesis to electrode fabrication are discussed. The bibliography includes 241 references.

  19. Toxicity of platinum compounds.

    Science.gov (United States)

    Hartmann, Jörg Thomas; Lipp, Hans-Peter

    2003-06-01

    Since the introduction of platinum-based combination chemotherapy, particularly cisplatin, the outcome of the treatment of many solid tumours has changed. The leading platinum compounds in cancer chemotherapy are cisplatin, carboplatin and oxaliplatin. They share some structural similarities; however, there are marked differences between them in therapeutic use, pharmacokinetics and adverse effects profiles [1-4]. Compared to cisplatin, carboplatin has inferior efficacy in germ-cell tumour, head and neck cancer and bladder and oesophageal carcinoma, whereas both drugs seem to have comparable efficacy in advanced non-small cell and small cell lung cancer as well as ovarian cancer [5-7]. Oxaliplatin belongs to the group of diaminocyclohexane platinum compounds. It is the first platinum-based drug that has marked efficacy in colorectal cancer when given in combination with 5-fluorouracil and folinic acid [8,9]. Other platinum compounds such as oral JM216, ZD0473, BBR3464 and SPI-77, which is a pegylated liposomal formulation of cisplatin, are still under investigation [10-13], whereas nedaplatin has been approved in Japan for the treatment of non-small cell lung cancer and other solid tumours. This review focuses on cisplatin, carboplatin and oxaliplatin.

  20. Toxic compounds in honey.

    Science.gov (United States)

    Islam, Md Nazmul; Khalil, Md Ibrahim; Islam, Md Asiful; Gan, Siew Hua

    2014-07-01

    There is a wealth of information about the nutritional and medicinal properties of honey. However, honey may contain compounds that may lead to toxicity. A compound not naturally present in honey, named 5-hydroxymethylfurfural (HMF), may be formed during the heating or preservation processes of honey. HMF has gained much interest, as it is commonly detected in honey samples, especially samples that have been stored for a long time. HMF is a compound that may be mutagenic, carcinogenic and cytotoxic. It has also been reported that honey can be contaminated with heavy metals such as lead, arsenic, mercury and cadmium. Honey produced from the nectar of Rhododendron ponticum contains alkaloids that can be poisonous to humans, while honey collected from Andromeda flowers contains grayanotoxins, which can cause paralysis of limbs in humans and eventually leads to death. In addition, Melicope ternata and Coriaria arborea from New Zealand produce toxic honey that can be fatal. There are reports that honey is not safe to be consumed when it is collected from Datura plants (from Mexico and Hungary), belladonna flowers and Hyoscamus niger plants (from Hungary), Serjania lethalis (from Brazil), Gelsemium sempervirens (from the American Southwest), Kalmia latifolia, Tripetalia paniculata and Ledum palustre. Although the symptoms of poisoning due to honey consumption may differ depending on the source of toxins, most common symptoms generally include dizziness, nausea, vomiting, convulsions, headache, palpitations or even death. It has been suggested that honey should not be considered a completely safe food.

  1. Antifungal Compounds from Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Tânia K. Shishido

    2015-04-01

    Full Text Available Cyanobacteria are photosynthetic prokaryotes found in a range of environments. They are infamous for the production of toxins, as well as bioactive compounds, which exhibit anticancer, antimicrobial and protease inhibition activities. Cyanobacteria produce a broad range of antifungals belonging to structural classes, such as peptides, polyketides and alkaloids. Here, we tested cyanobacteria from a wide variety of environments for antifungal activity. The potent antifungal macrolide scytophycin was detected in Anabaena sp. HAN21/1, Anabaena cf. cylindrica PH133, Nostoc sp. HAN11/1 and Scytonema sp. HAN3/2. To our knowledge, this is the first description of Anabaena strains that produce scytophycins. We detected antifungal glycolipopeptide hassallidin production in Anabaena spp. BIR JV1 and HAN7/1 and in Nostoc spp. 6sf Calc and CENA 219. These strains were isolated from brackish and freshwater samples collected in Brazil, the Czech Republic and Finland. In addition, three cyanobacterial strains, Fischerella sp. CENA 298, Scytonema hofmanni PCC 7110 and Nostoc sp. N107.3, produced unidentified antifungal compounds that warrant further characterization. Interestingly, all of the strains shown to produce antifungal compounds in this study belong to Nostocales or Stigonematales cyanobacterial orders.

  2. atmospheric volatile organic compounds

    Directory of Open Access Journals (Sweden)

    A. R. Koss

    2016-07-01

    organic compounds (VOCs that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument. Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1 NO+ is useful for isomerically resolved measurements of carbonyl species; (2 NO+ can achieve sensitive detection of small (C4–C8 branched alkanes but is not unambiguous for most; and (3 compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12–C15 n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.

  3. Antifungal compounds from cyanobacteria.

    Science.gov (United States)

    Shishido, Tânia K; Humisto, Anu; Jokela, Jouni; Liu, Liwei; Wahlsten, Matti; Tamrakar, Anisha; Fewer, David P; Permi, Perttu; Andreote, Ana P D; Fiore, Marli F; Sivonen, Kaarina

    2015-04-13

    Cyanobacteria are photosynthetic prokaryotes found in a range of environments. They are infamous for the production of toxins, as well as bioactive compounds, which exhibit anticancer, antimicrobial and protease inhibition activities. Cyanobacteria produce a broad range of antifungals belonging to structural classes, such as peptides, polyketides and alkaloids. Here, we tested cyanobacteria from a wide variety of environments for antifungal activity. The potent antifungal macrolide scytophycin was detected in Anabaena sp. HAN21/1, Anabaena cf. cylindrica PH133, Nostoc sp. HAN11/1 and Scytonema sp. HAN3/2. To our knowledge, this is the first description of Anabaena strains that produce scytophycins. We detected antifungal glycolipopeptide hassallidin production in Anabaena spp. BIR JV1 and HAN7/1 and in Nostoc spp. 6sf Calc and CENA 219. These strains were isolated from brackish and freshwater samples collected in Brazil, the Czech Republic and Finland. In addition, three cyanobacterial strains, Fischerella sp. CENA 298, Scytonema hofmanni PCC 7110 and Nostoc sp. N107.3, produced unidentified antifungal compounds that warrant further characterization. Interestingly, all of the strains shown to produce antifungal compounds in this study belong to Nostocales or Stigonematales cyanobacterial orders.

  4. Addressing Ozone Layer Depletion

    Science.gov (United States)

    Access information on EPA's efforts to address ozone layer depletion through regulations, collaborations with stakeholders, international treaties, partnerships with the private sector, and enforcement actions under Title VI of the Clean Air Act.

  5. Structured luminescence conversion layer

    Science.gov (United States)

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  6. Layered circle packings

    Directory of Open Access Journals (Sweden)

    David Dennis

    2005-01-01

    Full Text Available Given a bounded sequence of integers {d0,d1,d2,…}, 6≤dn≤M, there is an associated abstract triangulation created by building up layers of vertices so that vertices on the nth layer have degree dn. This triangulation can be realized via a circle packing which fills either the Euclidean or the hyperbolic plane. We give necessary and sufficient conditions to determine the type of the packing given the defining sequence {dn}.

  7. Compound liquid crystal microlens array with convergent and divergent functions.

    Science.gov (United States)

    Kang, Shengwu; Zhang, Xinyu

    2016-04-20

    Based on the common liquid crystal microlens, a new compound structure for a liquid crystal (LC) microlens array is proposed. The structure consists of two sub LC microlens arrays with properties of light divergence and convergence. The structure has two LC layers: one to form the positive sub lens, one for the negative. The patterned electrode and plane electrode are used in both sub microlens arrays. When two sub microlens arrays are electrically controlled separately, they can diverge or converge the incident light, respectively. As two sub microlens arrays are both applied on the voltage, the focal length of the compound LC microlens becomes larger than that of the LC microlens with a single LC layer. Another feature of a compound LC microlens array is that it can make the target contour become visible under intense light. The mechanisms are described in detail, and the experimental data are given.

  8. High-Tc Superconductors Based on FeAs Compounds

    CERN Document Server

    Izyumov, Yuri

    2010-01-01

    Physical properties and models of electronic structure are analyzed for a new class of high-TC superconductors which belong to iron-based layered compounds. Despite their variable chemical composition and differences in the crystal structure, these compounds possess similar physical characteristics, due to electron carriers in the FeAs layers and the interaction of these carriers with fluctuations of the magnetic order. A tremendous interest towards these materials is explained by the prospects of their practical use. In this monograph, a full picture of the formation of physical properties of these materials, in the context of existing theory models and electron structure studies, is given. The book is aimed at a broad circle of readers: physicists who study electronic properties of the FeAs compounds, chemists who synthesize them and specialists in the field of electronic structure calculations in solids. It is helpful not only to researchers active in the fields of superconductivity and magnetism, but also...

  9. Xenobiotic organic compounds in wastewater

    DEFF Research Database (Denmark)

    Eriksson, Eva; Baun, Anders; Henze, Mogens

    2002-01-01

    Information regarding the contents of xenobiotic organic compounds (XOCs) in wastewater is limited, but it has been shown that at least 900 different compounds / compound groups could potentially be present in grey wastewater. Analyses of Danish grey wastewater revealed the presence of several...... hundred of XOCs, among them mainly originating from hygiene products: chlorophenols, detergents and phthalates. Several compounds not deriving from hygiene products were also identified e.g. flame-retardants and drugs. A environmental hazard identification showed that a large number of compounds with high...... aquatic toxicity were present and that data for environmental fate could only be retrieved for about half of the compounds....

  10. Bi-layer functionally gradient thick film semiconducting methane sensors

    Indian Academy of Sciences (India)

    A Banerjee; A K Haldar; J Mondal; A Sen; H S Maiti

    2002-11-01

    Gas sensors based on metal oxide semiconductors like tin dioxide are widely used for the detection of toxic and combustible gases like carbon monoxide, methane and LPG. One of the problems of such sensors is their lack of sensitivity, which to some extent, can be circumvented by using different catalysts. However, highly reactive volatile organic compounds (VOC) coming from different industrial and domestic products (e.g. paints, lacquers, varnishes etc) can play havoc on such sensors and can give rise to false alarms. Any attempt to adsorb such VOCs (e.g. by using activated charcoal) results in sorption of the detecting gases (e.g. methane) too. To get round the problem, bi-layer sensors have been developed. Such tin oxide based functionally gradient bi-layer sensors have different compositions at the top and bottom layers. Here, instead of adsorbing the VOCs, they are allowed to interact and are consumed on the top layer of the sensors and a combustible gas like methane being less reactive, penetrates the top layer and interacts with the bottom layer. By modifying the chemical compositions of the top and bottom layers and by designing the electrode-lead wire arrangement properly, the top layer can be kept electrically shunted from the bottom layer and the electrical signal generated at the bottom layer from the combustible gas is collected. Such functionally gradient sensors, being very reliable, can find applications in domestic, industrial and strategic sectors.

  11. Magnetotelluric inversion for anisotropic conductivities in layered media

    Science.gov (United States)

    Pek, Josef; Santos, Fernando A. M.

    2006-10-01

    Electrical anisotropy in the Earth's crust and upper mantle has recently gained attention as a significant linking factor between electrical models and underlying structural and tectonic patterns. This interest has also motivated new methodological studies into the modelling and inversion for electrically anisotropic structures. We present an algorithm for the inversion of magnetotelluric data over layered anisotropic conductors which is a straightforward extension of the standard Occam 1-D inversion to anisotropic models. Owing to the essential limitation of magnetotellurics to resolve the complete conductivity tensor, we formulate the inversion for azimuthal anisotropy only. We treat the non-linear inverse problem as a multi-criterion minimization of the structure complexity, data misfit and anisotropy. To constrain the structure complexity, we employ the standard roughness penalty as well as non-quadratic penalties of the total variation and gradient support type that produce more focused model sections and thus conform better to the idea about sharp, non-diffuse boundaries of anisotropic structures in the Earth. Application of the anisotropy penalty is crucial for suppressing spurious anisotropy in the inverse models. We use a 2-D extension of the heuristic L-curve method to estimate the quasi-optimal penalty weights. With two non-linear iteration solvers, specifically the reweighted conjugate gradient method and the lagged diffusivity iteration, we can arrive at the minimum of the target functional, for one selected pair of regularization weights, typically after a few tens of iteration steps. To demonstrate the inverse solution, we present two simple yet not completely trivial synthetic examples, the first one based on data generated by a model with two anisotropic layers with discordant strikes, and the other showing possible misinterpretations in case a 1-D inversion with anisotropy is formally applied to data produced by simple 2-D block structures. Field

  12. Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

    Science.gov (United States)

    Choi, Sang; King, Glen; Park, Yeonjoon

    2009-01-01

    SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations. This innovation utilizes newly developed rhombohedral epitaxy of cubic semiconductors on trigonal substrates in order to solve the lattice mismatch problem of SiGe by using trigonal single crystals like sapphire (Al2O3) as substrate to give a unique growth-orientation to the SiGe layer, which is automatically controlled at the interface upon sapphire (0001). This technology is different from previous silicon on insulator (SOI) or SGOI (SiGe on insulator) technologies that use amorphous SiO2 as the growth plane. A cubic semiconductor crystal is a special case of a rhombohedron with the inter-planar angle, alpha = 90 deg. With a mathematical transformation, all rhombohedrons can be described by trigonal crystal lattice structures. Therefore, all cubic lattice constants and crystal planes (hkl) s can be transformed into those of trigonal crystal parameters. These unique alignments enable a new opportunity of perfect lattice matching conditions, which can eliminate misfit dislocations. Previously, these atomic alignments were thought to be impossible or very difficult. With the invention of a new x-ray diffraction measurement method here, growth of cubic semiconductors on trigonal crystals became possible. This epitaxy and lattice-matching condition can be applied not only to SiGe (111)/sapphire (0001) substrate relations, but also to other crystal structures and other materials, including similar crystal structures which have pointgroup rotational symmetries by 120 because the cubic (111) direction has 120 rotational symmetry. The use of slightly miscut (less than

  13. Offset Compound Gear Drive

    Science.gov (United States)

    Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

    2010-01-01

    The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths. Low-speed operation is accomplished in two meshes. For the purpose of illustrating the low-speed output operation, the following example pitch diameters are given. A 5.0 pitch diameter (PD) input gear to 7.50 PD (internal tooth) intermediate gear (0.667 reduction mesh), and a 7.50 PD (external tooth) intermediate gear to a 10.00 PD output gear (0.750 reduction mesh). Note that it is not required that the intermediate gears on the offset axis be of the same diameter. For this example, the resultant low-speed ratio is 2:1 (output speed = 0.500; product of stage one 0.667 reduction and stage two 0.750 stage reduction). The design is not restricted to the example pitch diameters, or output ratio. From the output gear, power is transmitted through a hollow drive shaft, which, in turn, drives a sprag during which time the main clutch is disengaged.

  14. Rubber compounding and processing

    CSIR Research Space (South Africa)

    John

    2014-06-01

    Full Text Available stream_source_info John_2014_ABSTRACT ONLY.pdf.txt stream_content_type text/plain stream_size 886 Content-Encoding ISO-8859-1 stream_name John_2014_ABSTRACT ONLY.pdf.txt Content-Type text/plain; charset=ISO-8859...-1 Handbook of Green Materials Processing Technologies, Properties and Applications Chapter 15 RUBBER COMPOUNDING AND PROCESSING MAYA JACOB JOHN1,2 1CSIR Materials Science and Manufacturing, Polymers and Composites Competence Area, P.O. Box 1124...

  15. Oligosilanylated Antimony Compounds

    Science.gov (United States)

    2015-01-01

    By reactions of magnesium oligosilanides with SbCl3, a number of oligosilanylated antimony compounds were obtained. When oligosilanyl dianions were used, either the expected cyclic disilylated halostibine was obtained or alternatively the formation of a distibine was observed. Deliberate formation of the distibine from the disilylated halostibine was achieved by reductive coupling with C8K. Computational studies of Sb–Sb bond energies, barriers of pyramidal inversion at Sb, and the conformational behavior of distibines provided insight for the understanding of the spectroscopic properties. PMID:25937691

  16. Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs.

    Science.gov (United States)

    Shih, Huan-Yu; Shiojiri, Makoto; Chen, Ching-Hsiang; Yu, Sheng-Fu; Ko, Chung-Ting; Yang, Jer-Ren; Lin, Ray-Ming; Chen, Miin-Jang

    2015-09-02

    High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2). In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

  17. The nature and origin of lateral composition modulations in short-period strained-layer superlattices

    Energy Technology Data Exchange (ETDEWEB)

    NORMAN,A.G.; AHRENKIEL,S.P.; MOUTINHO,H.R.; BALLIF,C.; ALJASSIM,M.M.; MASCARENHAS,A.; FOLLSTAEDT,DAVID M.; LEE,STEPHEN R.; RENO,JOHN L.; JONES,ERIC D.; MIRECKI-MILLUNCHICK,J.; TWESTEN,R.D.

    2000-01-27

    The nature and origin of lateral composition modulations in (AlAs){sub m}(InAs){sub n} SPSs grown by MBE on InP substrates have been investigated by XRD, AFM, and TEM. Strong modulations were observed for growth temperatures between {approx} 540 and 560 C. The maximum strength of modulations was found for SPS samples with InAs mole fraction x (=n/(n+m)) close to {approx} 0.50 and when n {approx} m {approx} 2. The modulations were suppressed at both high and low values of x. For x >0.52 (global compression) the modulations were along the <100> directions in the (001) growth plane. For x < 0.52 (global tension) the modulations were along the two <310> directions rotated {approx} {+-} 27{degree} from [110] in the growth plane. The remarkably constant wavelength of the modulations, between {approx} 20--30 nm, and the different modulation directions observed, suggest that the origin of the modulations is due to surface roughening associated with the high misfit between the individual SPS layers and the InP substrate. Highly uniform unidirectional modulations have been grown, by control of the InAs mole fraction and growth on suitably offcut substrates, which show great promise for application in device structures.

  18. Special Risks of Pharmacy Compounding

    Science.gov (United States)

    ... Consumer Updates RSS Feed The Special Risks of Pharmacy Compounding Get Consumer Updates by E-mail Consumer ... page: A Troubling Trend What You Can Do Pharmacy compounding is a practice in which a licensed ...

  19. Study of tectonic layering motion and layering mineralization in the Tongling metallogenic cluster

    Institute of Scientific and Technical Information of China (English)

    吴淦国; 张达; 臧文拴

    2003-01-01

    Analysis of the deep tectonics and cover tectonic deformations shows that tectonic layering motion is a typical lithospheric characteristic in the Tongling area and the metallogenic belt of the middle-lower Yangtze. Controlling of the deep tectonosphere over the shallow-seated tectonosphere involves various grades of tectonic layering motions. Multi-layer, multi-grade, and multi-directional gliding tectonics are the specific modes of tectonic layering motions in the cover of the Tongling metallogenic cluster. The gliding tectonics developed based on S-shaped folds of the Indosinian, and was continuously active in the Yanshanian. They correspond to the deformation systems of the EW and NNE extensions. The control of tectonic layering motion acts against ore-forming processes, the different interlayer gliding belts can easily form different genetic-type deposits, and the ore-forming features of different parts of the same gliding layer are different. All of these characters are closely related to tectonic gliding mechanisms, tectonic compounding characteristics, features of metallogenic wall rocks, and types of ore-forming hydrothermal solutions.

  20. Optimizing Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Spatial compound images are constructed from synthetic aperture data acquired using a linear phased-array transducer. Compound images of wires, tissue, and cysts are created using a method, which allows both transmit and receive compounding without any loss in temporal resolution. Similarly to co...

  1. Superfluid Boundary Layer

    Science.gov (United States)

    Stagg, G. W.; Parker, N. G.; Barenghi, C. F.

    2017-03-01

    We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.

  2. Layered Systems Engineering Engines

    Science.gov (United States)

    Breidenthal, Julian C.; Overman, Marvin J.

    2009-01-01

    A notation is described for depicting the relationships between multiple, contemporaneous systems engineering efforts undertaken within a multi-layer system-of-systems hierarchy. We combined the concepts of remoteness of activity from the end customer, depiction of activity on a timeline, and data flow to create a new kind of diagram which we call a "Layered Vee Diagram." This notation is an advance over previous notations because it is able to be simultaneously precise about activity, level of granularity, product exchanges, and timing; these advances provide systems engineering managers a significantly improved ability to express and understand the relationships between many systems engineering efforts. Using the new notation, we obtain a key insight into the relationship between project duration and the strategy selected for chaining the systems engineering effort between layers, as well as insights into the costs, opportunities, and risks associated with alternate chaining strategies.

  3. of polyphenolic compounds in Ilex Sp.

    Directory of Open Access Journals (Sweden)

    Zwyrzykowska Anna

    2015-11-01

    Full Text Available Natural compounds are an important source of desired biological activity which help to improve nutritional status, enhance productivity and bring many health benefits. The leaves of the Ilex paraguariensis (Aquifoliaceae are used for preparing a beverage known as yerba mate and represent a proven source of natural polyphenols which are known to foster biological activity with the emphasis on antioxidant properties. In present work we focused on the polyphenolic content of air-dried leaves of Ilex aquifolium L., Ilex aquifolium ‘Argentea Mariginata’, Ilex meserveae ‘Blue Angel’, and a commercially available mate as the reference product. Liquid chromatography combined with mass spectrometry (HPLC and LC-MS and thin layer chromatography (TLC, were used to establish polyphenolic substances content in aqueous methanolic extracts obtained from the biological matter. Up to 20 polyphenolic compounds were identified in the extracts, including rutin, quinic acid and its caffeoyl esters, i.e. chlorogenic acid and its isomers as well as dicaffeoyl derivatives. We took chlorogenic acid and rutin as reference compounds to quantify their levels in the extracts. It was determined that in all tested plants, high levels of these antioxidants were present. This led us to the conclusion that their leaves might serve as valuable food additives.

  4. Semiconducting III-V compounds

    CERN Document Server

    Hilsum, C; Henisch, Heinz R

    1961-01-01

    Semiconducting III-V Compounds deals with the properties of III-V compounds as a family of semiconducting crystals and relates these compounds to the monatomic semiconductors silicon and germanium. Emphasis is placed on physical processes that are peculiar to III-V compounds, particularly those that combine boron, aluminum, gallium, and indium with phosphorus, arsenic, and antimony (for example, indium antimonide, indium arsenide, gallium antimonide, and gallium arsenide).Comprised of eight chapters, this book begins with an assessment of the crystal structure and binding of III-V compounds, f

  5. Reinforcing the mineral layer

    Energy Technology Data Exchange (ETDEWEB)

    Pishchulin, V.V.; Kuntsevich, V.I.; Seryy, A.M.; Shirokov, A.P.

    1980-05-15

    A way of reinforcing the mineral layer includes drilling holes and putting in anchors that are longer than the width of the layer strip being extracted. It also includes shortening the anchors as the strip is mined and reinforcing the remaining part of the anchor in the mouth of the hole. To increase the productivity and safety of the work, the anchors are shortened by cutting them as the strip is mined and are reinforced through wedging. The device for doing this has auxilliary lengthwise grooves in the shaft located along its length at an interval equal to the width of the band being extracted.

  6. Naming the Soft Tissue Layers of the Temporoparietal Region: Unifying Anatomic Terminology Across Surgical Disciplines

    NARCIS (Netherlands)

    K.M. Davidge; W.R. van Furth; A. Agur; M. Cusimano

    2010-01-01

    BACKGROUND: The complexity of temporoparietal anatomy is compounded by inconsistent nomenclature. OBJECTIVE: To provide a comprehensive review of the variations in terminology and anatomic descriptions of the temporoparietal soft tissue layers, with the aim of improving learning and communication ac

  7. Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk

    Medical ultrasound imaging is used for many purposes, e.g. for localizing and classifying cysts, lesions, and other processes. Almost any mass is first observed using B-mode imaging and later classified using e.g. color flow, strain, or attenuation imaging. It is therefore important that the B....... The method is investigated using simulations and through measurements using both phased array and convex array transducers. The images all show an improved contrast compared to images without compounding, and by construction, imaging using an improved frame rate is possible. Using a phased array transducer...... and the limiting factor is the amount of memory IO resources available. An equally high demand for memory throughput is found in the computer gaming industry, where a large part of the processing takes place on the graphics processing unit (GPU). Using the GPU, a framework for synthetic aperture imaging...

  8. An Undergraduate Organic Experiment Using Thin-Layer Chromatography.

    Science.gov (United States)

    Jones, Taylor B.; Jones, Tappey H.

    1985-01-01

    The separation of derivatives of aliphatic compounds (2,4-dinitrophenylhydrazones) is used to introduce methods and techniques typically employed in thin layer chromatography and to provide a clear illustration of chromatographic principles in general. Procedures used in the separation are presented. (JN)

  9. Chronopotentiometric study of intercalation of layered III-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bakhmatyuk, B.P.; Grigorchak, I.I.; Kaminskii, V.M.; Kovalyuk, Z.D.; Yurtsenyuk, S.P.

    1985-04-01

    The known group of materials open to intercalation (i.e., the incorporation of foreign ions, atoms, or molecules into the space between layers of layered crystals) has recently been enlarged by the layered semiconducting monochalcogenides of indium and gallium. This article is concerned with an electrochemical investigation of their intercalation process. The chronopotentiograms for the reduction and oxidation of electrodes made of the layered monoselenides of indium and gallium in 1 M lithium perchlorate solution in propylene carbonate were examined. The electrodes studied were examined by x-rays before and after intercalation. It is indicated that the intercalation of InSe and GaSe with lithium yields nonstoichiometric phases in the range of 0 is less than x is less than or equal to 1. Using the equilibrium potentials of the intercalated phases and known relations, the free energies of these compounds and of their formation can be determined. The electrochemical intercalation leads to the formation of ternary compounds Li /SUB x/ InSe and Li /SUB x/ GaSe. The free energies of formation of these compounds increase with increasing degree of reduction of the compounds. The intercalation of indium and gallium monoselenide with lithium can be regarded as reversible.

  10. Improved electron transport layer

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution...

  11. Physical layer network coding

    DEFF Research Database (Denmark)

    Fukui, Hironori; Popovski, Petar; Yomo, Hiroyuki

    2014-01-01

    Physical layer network coding (PLNC) has been proposed to improve throughput of the two-way relay channel, where two nodes communicate with each other, being assisted by a relay node. Most of the works related to PLNC are focused on a simple three-node model and they do not take into account...

  12. Layer-Cake Earth

    Science.gov (United States)

    Tedford, Rebecca; Warny, Sophie

    2006-01-01

    In this article, the authors offer a safe, fun, effective way to introduce geology concepts to elementary school children of all ages: "coring" layer cakes. This activity introduces the concepts and challenges that geologists face and at the same time strengthens students' inferential, observational, and problem-solving skills. It also addresses…

  13. EHD lubricating layer

    Energy Technology Data Exchange (ETDEWEB)

    Shvarts, I.A.

    1978-01-01

    The simplest model of an EHD lubricating layer consists of a unipolarly charged nonconducting viscous fluid between two parallel or slightly inclined nonconducting plates. The performance of such a layer is analyzed here on the basis of the fundamental EHD equations, with a plane-parallel approximation of the flow of a thin layer under a variable upper boundary. The results of the solution indicate that the bearing capacity of such a layer between parallel plates does not depend on the viscosity of the fluid, but is proportional to the energy density of the electric field in vacuum. With the plates not parallel, the bearing capacity depends on the mobility and the diffusion of the charged fluid particles. In either case the energy of the electric field can be made to compensate for the energy dissipation due to viscous friction, and in this case or with overcompensation such as EHD bearing becomes an EHD generator. Most valuable for practical applications are fluids with a high dielectric permittivity, such as ammonia and hydrogen chloride at cryogenic temperatures. 5 references, 1 figure.

  14. MITRE sensor layer prototype

    Science.gov (United States)

    Duff, Francis; McGarry, Donald; Zasada, David; Foote, Scott

    2009-05-01

    The MITRE Sensor Layer Prototype is an initial design effort to enable every sensor to help create new capabilities through collaborative data sharing. By making both upstream (raw) and downstream (processed) sensor data visible, users can access the specific level, type, and quantities of data needed to create new data products that were never anticipated by the original designers of the individual sensors. The major characteristic that sets sensor data services apart from typical enterprise services is the volume (on the order of multiple terabytes) of raw data that can be generated by most sensors. Traditional tightly coupled processing approaches extract pre-determined information from the incoming raw sensor data, format it, and send it to predetermined users. The community is rapidly reaching the conclusion that tightly coupled sensor processing loses too much potentially critical information.1 Hence upstream (raw and partially processed) data must be extracted, rapidly archived, and advertised to the enterprise for unanticipated uses. The authors believe layered sensing net-centric integration can be achieved through a standardize-encapsulate-syndicateaggregate- manipulate-process paradigm. The Sensor Layer Prototype's technical approach focuses on implementing this proof of concept framework to make sensor data visible, accessible and useful to the enterprise. To achieve this, a "raw" data tap between physical transducers associated with sensor arrays and the embedded sensor signal processing hardware and software has been exploited. Second, we encapsulate and expose both raw and partially processed data to the enterprise within the context of a service-oriented architecture. Third, we advertise the presence of multiple types, and multiple layers of data through geographic-enabled Really Simple Syndication (GeoRSS) services. These GeoRSS feeds are aggregated, manipulated, and filtered by a feed aggregator. After filtering these feeds to bring just the type

  15. Framework structures of interconnected layers in calcium iron arsenides.

    Science.gov (United States)

    Stürzer, Tobias; Hieke, Christine; Löhnert, Catrin; Nitsche, Fabian; Stahl, Juliane; Maak, Christian; Pobel, Roman; Johrendt, Dirk

    2014-06-16

    The new calcium iron arsenide compounds Ca(n(n+1)/2)(Fe(1-x)M(x))(2+3n)M'(n(n-1)/2)As((n+1)(n+2)/2) (n = 1-3; M = Nb, Pd, Pt; M' = □, Pd, Pt) were synthesized and their crystal structures determined by single-crystal X-ray diffraction. The series demonstrates the structural flexibility of iron arsenide materials, which otherwise prefer layered structures, as is known from the family of iron-based superconductors. In the new compounds, iron arsenide tetrahedral layers are bridged by iron-centered pyramids, giving rise to so far unknown frameworks of interconnected FeAs layers. Channels within the structures are occupied with calcium and palladium or platinum, respectively. Common basic building blocks are identified that lead to a better understanding of the building principles of these structures and their relation to CaFe4As3.

  16. Boundary layer transition studies

    Science.gov (United States)

    Watmuff, Jonathan H.

    1995-02-01

    A small-scale wind tunnel previously used for turbulent boundary layer experiments was modified for two sets of boundary layer transition studies. The first study concerns a laminar separation/turbulent reattachment. The pressure gradient and unit Reynolds number are the same as the fully turbulent flow of Spalart and Watmuff. Without the trip wire, a laminar layer asymptotes to a Falkner & Skan similarity solution in the FPG. Application of the APG causes the layer to separate and a highly turbulent and approximately 2D mean flow reattachment occurs downstream. In an effort to gain some physical insight into the flow processes a small impulsive disturbance was introduced at the C(sub p) minimum. The facility is totally automated and phase-averaged data are measured on a point-by-point basis using unprecedently large grids. The evolution of the disturbance has been tracked all the way into the reattachment region and beyond into the fully turbulent boundary layer. At first, the amplitude decays exponentially with streamwise distance in the APG region, where the layer remains attached, i.e. the layer is viscously stable. After separation, the rate of decay slows, and a point of minimum amplitude is reached where the contours of the wave packet exhibit dispersive characteristics. From this point, exponential growth of the amplitude of the disturbance is observed in the detached shear layer, i.e. the dominant instability mechanism is inviscid. A group of large-scale 3D vortex loops emerges in the vicinity of the reattachment. Remarkably, the second loop retains its identify far downstream in the turbulent boundary layer. The results provide a level of detail usually associated with CFD. Substantial modifications were made to the facility for the second study concerning disturbances generated by Suction Holes for laminar flow Control (LFC). The test section incorporates suction through interchangeable porous test surfaces. Detailed studies have been made using isolated

  17. Boundary layer transition studies

    Science.gov (United States)

    Watmuff, Jonathan H.

    1995-01-01

    A small-scale wind tunnel previously used for turbulent boundary layer experiments was modified for two sets of boundary layer transition studies. The first study concerns a laminar separation/turbulent reattachment. The pressure gradient and unit Reynolds number are the same as the fully turbulent flow of Spalart and Watmuff. Without the trip wire, a laminar layer asymptotes to a Falkner & Skan similarity solution in the FPG. Application of the APG causes the layer to separate and a highly turbulent and approximately 2D mean flow reattachment occurs downstream. In an effort to gain some physical insight into the flow processes a small impulsive disturbance was introduced at the C(sub p) minimum. The facility is totally automated and phase-averaged data are measured on a point-by-point basis using unprecedently large grids. The evolution of the disturbance has been tracked all the way into the reattachment region and beyond into the fully turbulent boundary layer. At first, the amplitude decays exponentially with streamwise distance in the APG region, where the layer remains attached, i.e. the layer is viscously stable. After separation, the rate of decay slows, and a point of minimum amplitude is reached where the contours of the wave packet exhibit dispersive characteristics. From this point, exponential growth of the amplitude of the disturbance is observed in the detached shear layer, i.e. the dominant instability mechanism is inviscid. A group of large-scale 3D vortex loops emerges in the vicinity of the reattachment. Remarkably, the second loop retains its identify far downstream in the turbulent boundary layer. The results provide a level of detail usually associated with CFD. Substantial modifications were made to the facility for the second study concerning disturbances generated by Suction Holes for laminar flow Control (LFC). The test section incorporates suction through interchangeable porous test surfaces. Detailed studies have been made using isolated

  18. The role of the alkali and chalcogen atoms on the stability of the layered chalcogenide \\mathbf{{{A}_{2}}{{M}^{II}}M_{3}^{\\,IV}{{Q}_{8}}} (A  =  alkali-metal M  =  metal-cations Q  =  chalcogen) compounds: a density functional theory investigation within van der Waals corrections

    Science.gov (United States)

    Besse, Rafael; Da Silva, Juarez L. F.

    2017-01-01

    There is a great interest to design two-dimensional (2D) chalcogenide materials, however, our atomistic understanding of the major physical parameters that drive the formation of 2D or three-dimensional (3D) chalcogenides is far from satisfactory, in particular, for complex quaternary systems. To address this problem, we selected a set of quaternary 2D and 3D chalcogenide compounds, namely, {{\\text{A}}2}\\text{ZnS}{{\\text{n}}3}{{\\text{Q}}8} (A  =  Li, K, Cs; Q  =  S, Se, Te), which were investigated by density functional theory calculations within van der Waals (vdW) corrections. Employing experimental crystal structures and well designed crystal modifications, we found that the average atomic radius of the alkali-metal, A, and chalcogen, Q, species play a crucial role in the stability of the 2D structures. For example, the 2D structures are energetically favored for smaller (R1.8~{\\mathring{\\text{A}}}) average atomic radius, while 3D structures are favored at intermediate average atomic radius. Those results are explained in terms of strain minimization and Coulomb repulsion of the anionic species in the structure framework. Furthermore, the equilibrium lattice parameters are in excellent agreement with experimental results. Thus, the present insights can help in the design of stable quartenary 2D chalcogenide compounds.

  19. A class of fascinating optoelectronic materials: Triarylboron compounds

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Triarylboron compounds are significant optoelectronic materials due to their excellent emissive and electron-transport properties,and could be applied in organic light-emitting diodes as emissive and/or electron-transport layers.Triarylboron compounds have vacant pπ orbital and have received increasing interest as fluoride ion and cyanide ion sensors utilizing specific Lewis acid-base interaction.This review summarizes their structural characteristics,optical properties and applications in chemosensors for anions and optoelectronic devices developed in recent years and discusses the problems and prospects.

  20. Peeling Back the Layers

    Science.gov (United States)

    2004-01-01

    NASA's Mars Exploration Rover Spirit took this panoramic camera image of the rock target named 'Mazatzal' on sol 77 (March 22, 2004). It is a close-up look at the rock face and the targets that will be brushed and ground by the rock abrasion tool in upcoming sols. Mazatzal, like most rocks on Earth and Mars, has layers of material near its surface that provide clues about the history of the rock. Scientists believe that the top layer of Mazatzal is actually a coating of dust and possibly even salts. Under this light coating may be a more solid portion of the rock that has been chemically altered by weathering. Past this layer is the unaltered rock, which may give scientists the best information about how Mazatzal was formed. Because each layer reveals information about the formation and subsequent history of Mazatzal, it is important that scientists get a look at each of them. For this reason, they have developed a multi-part strategy to use the rock abrasion tool to systematically peel back Mazatzal's layers and analyze what's underneath with the rover's microscopic imager, and its Moessbauer and alpha particle X-ray spectrometers. The strategy began on sol 77 when scientists used the microscopic imager to get a closer look at targets on Mazatzal named 'New York,' 'Illinois' and 'Arizona.' These rock areas were targeted because they posed the best opportunity for successfully using the rock abrasion tool; Arizona also allowed for a close-up look at a range of tones. On sol 78, Spirit's rock abrasion tool will do a light brushing on the Illinois target to preserve some of the surface layers. Then, a brushing of the New York target should remove the top coating of any dust and salts and perhaps reveal the chemically altered rock underneath. Finally, on sol 79, the rock abrasion tool will be commanded to grind into the New York target, which will give scientists the best chance of observing Mazatzal's interior. The Mazatzal targets were named after the home states of

  1. Public chemical compound databases.

    Science.gov (United States)

    Williams, Anthony J

    2008-05-01

    The internet has rapidly become the first port of call for all information searches. The increasing array of chemistry-related resources that are now available provides chemists with a direct path to the information that was previously accessed via library services and was limited by commercial and costly resources. The diversity of the information that can be accessed online is expanding at a dramatic rate, and the support for publicly available resources offers significant opportunities in terms of the benefits to science and society. While the data online do not generally meet the quality standards of manually curated sources, there are efforts underway to gather scientists together and 'crowdsource' an improvement in the quality of the available data. This review discusses the types of public compound databases that are available online and provides a series of examples. Focus is also given to the benefits and disruptions associated with the increased availability of such data and the integration of technologies to data mine this information.

  2. Tin compounds and insect fauna

    Energy Technology Data Exchange (ETDEWEB)

    Butovskiy, R.O.

    1985-03-01

    A review of the literature of tin compounds serving as pesticides has resulted in the identification of 11 widely used compounds, both organic and inorganic, with largely fungicidal activity. Organotin compounds seem to be limited in use to the control of insect pests, with the majority of the compounds consisting of Sn(IV) and falling into the following four categories: R/sub 4/Sn, R/sub 3/SNX, R/sub 2/SnX/sub 2/, and RSnX/sub 3/, where R = aliphatic or aromatic hydrocarbon radicals, and X = organic or inorganic substituent. The insecticidal activity of these compounds appears to rest on inhibition of ATPase and uncoupling of oxidative phosphorylation. As a result, these compounds act as larvicides, ovicides and imagocides. 77 references.

  3. Ionic Graphitization of Ultrathin Films of Ionic Compounds.

    Science.gov (United States)

    Kvashnin, A G; Pashkin, E Y; Yakobson, B I; Sorokin, P B

    2016-07-21

    On the basis of ab initio density functional calculations, we performed a comprehensive investigation of the general graphitization tendency in rocksalt-type structures. In this paper, we determine the critical slab thickness for a range of ionic cubic crystal systems, below which a spontaneous conversion from a cubic to a layered graphitic-like structure occurs. This conversion is driven by surface energy reduction. Using only fundamental parameters of the compounds such as the Allen electronegativity and ionic radius of the metal atom, we also develop an analytical relation to estimate the critical number of layers.

  4. Sesquiterpene compounds from Inula viscosa.

    Science.gov (United States)

    Fontana, Gianfranco; La Rocca, Salvatore; Passannanti, Salvatore; Paternostro, Maria Pia

    2007-07-20

    Two new compounds, 2,5-dihydroxyisocostic acid and 2,3-dihydroxycostic acid together with three known sesquiterpene compounds, Isocostic acid, Carabrone and Tomentosin, have been isolated from the acetone extract of Inula viscosa (L.) Aiton. The structures of all new compounds were determined by spectroscopic methods, in particular 1D and 2D (1)H- and (13)C-NMR. The (13)C-NMR spectra of Isocostic acid and of Tomentosin are reported here for the first time.

  5. Potential Risks of Pharmacy Compounding

    OpenAIRE

    Gudeman, Jennifer; Jozwiakowski, Michael; Chollet, John; Randell, Michael

    2013-01-01

    Pharmacy compounding involves the preparation of customized medications that are not commercially available for individual patients with specialized medical needs. Traditional pharmacy compounding is appropriate when done on a small scale by pharmacists who prepare the medication based on an individual prescription. However, the regulatory oversight of pharmacy compounding is significantly less rigorous than that required for Food and Drug Administration (FDA)-approved drugs; as such, compoun...

  6. Natural compounds with herbicidal activity

    Directory of Open Access Journals (Sweden)

    Pasquale Montemurro

    2011-02-01

    Full Text Available Research about phytotoxic activity of natural compounds could lead both to find new herbicidal active ingredients and to plan environmental friendly weed control strategies. Particularly, living organisms could be a source of compounds that are impossible, for their complexity, to synthesize artificially. More over, they could have alternative sites of action respect to the known chemical herbicides and, due to their origin, they should be more environmental safe. Many living organism, such as bacteria, fungi, insects, lichens and plants, are able to produce bioactive compounds. They generally are secondary metabolites or simply waste molecules. In this paper we make a review about these compounds, highlighting potential and constraints.

  7. Transition Metal Compounds Towards Holography

    Directory of Open Access Journals (Sweden)

    Volker Dieckmann

    2012-06-01

    Full Text Available We have successfully proposed the application of transition metal compounds in holographic recording media. Such compounds feature an ultra-fast light-induced linkage isomerization of the transition-metal–ligand bond with switching times in the sub-picosecond regime and lifetimes from microseconds up to hours at room temperature. This article highlights the photofunctionality of two of the most promising transition metal compounds and the photophysical mechanisms that are underlying the hologram recording. We present the latest progress with respect to the key measures of holographic media assembled from transition metal compounds, the molecular embedding in a dielectric matrix and their impressive potential for modern holographic applications.

  8. Crack layer theory

    Science.gov (United States)

    Chudnovsky, A.

    1984-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  9. Structural properties of tensily strained Si layers grown on SiGe(100), (110), and (111) virtual substrates

    Science.gov (United States)

    Destefanis, V.; Rouchon, D.; Hartmann, J. M.; Papon, A. M.; Baud, L.; Crisci, A.; Mermoux, M.

    2009-08-01

    through the emission of misfit dislocations, twins, and stacking faults. Promising results have been obtained for t-Si layers on (110) SiGe VS while the technological usefulness of the (111) ones is more questionable.

  10. Layered bismuth vanadate ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Osipyan, V.G.; Savchenko, L.M.; Elbakyan, V.L.; Avakyan, P.B.

    1987-08-01

    The authors synthesize new layered bismuth vanadate ferroelectrics. The x-ray diffraction characteristics of Bi/sub 2/VO/sub 5.5/ are shown. Thermal expansion of ceramics with various compositions are presented, as are the temperature dependences of the dielectric constant of the ceramic with various compositions. Unit-cell parameters, Curie temperature, electrical conductivity and the dielectric characteristics of the compositions studied are shown.

  11. Boundary-layer theory

    CERN Document Server

    Schlichting (Deceased), Hermann

    2017-01-01

    This new edition of the near-legendary textbook by Schlichting and revised by Gersten presents a comprehensive overview of boundary-layer theory and its application to all areas of fluid mechanics, with particular emphasis on the flow past bodies (e.g. aircraft aerodynamics). The new edition features an updated reference list and over 100 additional changes throughout the book, reflecting the latest advances on the subject.

  12. Physical Layer Network Coding

    DEFF Research Database (Denmark)

    Fukui, Hironori; Yomo, Hironori; Popovski, Petar

    2013-01-01

    Physical layer network coding (PLNC) has the potential to improve throughput of multi-hop networks. However, most of the works are focused on the simple, three-node model with two-way relaying, not taking into account the fact that there can be other neighboring nodes that can cause/receive inter......Physical layer network coding (PLNC) has the potential to improve throughput of multi-hop networks. However, most of the works are focused on the simple, three-node model with two-way relaying, not taking into account the fact that there can be other neighboring nodes that can cause....../receive interference. The way to deal with this problem in distributed wireless networks is usage of MAC-layer mechanisms that make a spatial reservation of the shared wireless medium, similar to the well-known RTS/CTS in IEEE 802.11 wireless networks. In this paper, we investigate two-way relaying in presence...

  13. Multifunctional layered magnetic composites

    Directory of Open Access Journals (Sweden)

    Maria Siglreitmeier

    2015-01-01

    Full Text Available A fabrication method of a multifunctional hybrid material is achieved by using the insoluble organic nacre matrix of the Haliotis laevigata shell infiltrated with gelatin as a confined reaction environment. Inside this organic scaffold magnetite nanoparticles (MNPs are synthesized. The amount of MNPs can be controlled through the synthesis protocol therefore mineral loadings starting from 15 wt % up to 65 wt % can be realized. The demineralized organic nacre matrix is characterized by small-angle and very-small-angle neutron scattering (SANS and VSANS showing an unchanged organic matrix structure after demineralization compared to the original mineralized nacre reference. Light microscopy and confocal laser scanning microscopy studies of stained samples show the presence of insoluble proteins at the chitin surface but not between the chitin layers. Successful and homogeneous gelatin infiltration in between the chitin layers can be shown. The hybrid material is characterized by TEM and shows a layered structure filled with MNPs with a size of around 10 nm. Magnetic analysis of the material demonstrates superparamagnetic behavior as characteristic for the particle size. Simulation studies show the potential of collagen and chitin to act as nucleators, where there is a slight preference of chitin over collagen as a nucleator for magnetite. Colloidal-probe AFM measurements demonstrate that introduction of a ferrogel into the chitin matrix leads to a certain increase in the stiffness of the composite material.

  14. Saturn's Stratospheric Oxygen Compounds

    Science.gov (United States)

    Romani, Paul N.; Delgado Díaz, Héctor E.; Bjoraker, Gordon; Hesman, Brigette; Achterberg, Richard

    2016-10-01

    There are three known oxygenated species present in Saturn's upper atmosphere: H2O, CO and CO2. The ultimate source of the water must be external to Saturn as Saturn's cold tropopause effectively prevents any internal water from reaching the upper atmosphere. The carbon monoxide and dioxide source(s) could be internal, external, produced by the photochemical interaction of water with Saturn's stratospheric hydrocarbons or some combination of all of these. At this point it is not clear what the external source(s) are.Cassini's Composite InfraRed Spectrometer (CIRS) has detected emission lines of H2O and CO2 (Hesman et al., DPS 2015, 311.16 & Abbas et al. 2013, Ap. J. doi:10.1088/0004-637X/776/2/73) on Saturn. CIRS also retrieves the temperature of the stratosphere using CH4 lines at 7.7 microns. Using CIRS retrieved temperatures, the mole fraction of H2O at the 0.5-5 mbar level can be retrieved and the CO2 mole fraction at ~1-10 mbar. Coupled with ground based observations of CO (Cavalié et al., 2010, A&A, DOI: 10.1051/0004-6361/200912909) these observations provide a complete oxygen compound data set to test photochemical models.Preliminary results will be presented with an emphasis on upper limit analysis to determine the percentage of stratospheric CO and CO2 that can be produced photochemically from CIRS observational constraints on the H2O profile.

  15. Antimicrobial compounds in tears.

    Science.gov (United States)

    McDermott, Alison M

    2013-12-01

    The tear film coats the cornea and conjunctiva and serves several important functions. It provides lubrication, prevents drying of the ocular surface epithelia, helps provide a smooth surface for refracting light, supplies oxygen and is an important component of the innate defense system of the eye providing protection against a range of potential pathogens. This review describes both classic antimicrobial compounds found in tears such as lysozyme and some more recently identified such as members of the cationic antimicrobial peptide family and surfactant protein-D as well as potential new candidate molecules that may contribute to antimicrobial protection. As is readily evident from the literature review herein, tears, like all mucosal fluids, contain a plethora of molecules with known antimicrobial effects. That all of these are active in vivo is debatable as many are present in low concentrations, may be influenced by other tear components such as the ionic environment, and antimicrobial action may be only one of several activities ascribed to the molecule. However, there are many studies showing synergistic/additive interactions between several of the tear antimicrobials and it is highly likely that cooperativity between molecules is the primary way tears are able to afford significant antimicrobial protection to the ocular surface in vivo. In addition to effects on pathogen growth and survival some tear components prevent epithelial cell invasion and promote the epithelial expression of innate defense molecules. Given the protective role of tears a number of scenarios can be envisaged that may affect the amount and/or activity of tear antimicrobials and hence compromise tear immunity. Two such situations, dry eye disease and contact lens wear, are discussed here.

  16. Volatile organic compound detection using nanostructured copolymers.

    Science.gov (United States)

    Li, Bo; Sauvé, Genevieve; Iovu, Mihaela C; Jeffries-El, Malika; Zhang, Rui; Cooper, Jessica; Santhanam, Suresh; Schultz, Lawrence; Revelli, Joseph C; Kusne, Aaron G; Kowalewski, Tomasz; Snyder, Jay L; Weiss, Lee E; Fedder, Gary K; McCullough, Richard D; Lambeth, David N

    2006-08-01

    Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as the active layer in volatile organic compound (VOC) chemresistor sensors. While the regioregular polythiophene polymer chain provides a charge conduction path, its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a block copolymer or by making a random copolymer of polythiophene with different alkyl side chains. The copolymers were exposed to a variety of VOC vapors, and the electrical conductivity of these copolymers increased or decreased depending upon the polymer composition and the specific analytes. Measurements were made at room temperature, and the responses were found to be fast and appeared to be completely reversible. Using various copolymers of polythiophene in a sensor array can provide much better discrimination to various analytes than existing solid state sensors. Our data strongly indicate that several sensing mechanisms are at play simultaneously, and we briefly discuss some of them.

  17. Organic Electrofluorescent Materials Using Pyridine-Containing Macrocyclic Compounds

    Institute of Scientific and Technical Information of China (English)

    Tingxi LI; Long FU; Wenwen YU; Renhe HUANG

    2008-01-01

    Novel pyridine-containing macrocyclic compounds, such as 6,12,19,25-tetramethyl-7,11,20,24-dinitrilo-dibenzo[b,m]l,4,12,15-tetra-azacyclodoc osine (TMCD), were synthesized and used as electron transport layer in organic electroluminescent devices. Devices with a structure of glass/indium-tin oxide/arylamine derivative/tris(quinolinolato)aluminum(Ⅲ) (AIq)/TMCD/LiF/AI exhibited green emission from the Alq layer with external quantum efficiency of 0.84% and luminous efficiency of 1.3 lm/W. The derivatives of TMCD were synthesized and characterized as well. These compounds were also found to be useful as the electron-transporting materials in organic electroluminescent devices.

  18. Formation and growth model of B-Al permeation layer of Steel 45

    Institute of Scientific and Technical Information of China (English)

    吉泽升; 李庆芬; 李冬华

    2002-01-01

    The B-Al permeation layers of Steel 45 were studied by means of SEM, TEM and XRD. The formation and growth model of permeation layer was proposed. The layer formation, growth and the migration behaviors of B were discussed. It is suggested that the diffusion of Al is deferred when the surface was covered by borides and aluminize compounds are surrounded by borides with the further growing of borides.

  19. Band Gap Engineering and Layer-by-Layer Band Gap Mapping of Selenium-doped Molybdenum Disulfide

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yongji [Rice University; Liu, Zheng [Rice University; Lupini, Andrew R [ORNL; Lin, Junhao [ORNL; Pantelides, Sokrates T [ORNL; Pennycook, Stephen J [ORNL; Zhou, Wu [ORNL; Ajayan, Pullikel M [Rice University

    2014-01-01

    Ternary two-dimensional dichalcogenide alloys exhibit compositionally modulated electronic structure and hence, control of dopant concentration within each layer of these layered compounds provides a powerful way to modify their properties. The challenge then becomes quantifying and locating the dopant atoms within each layer in order to better understand and fine-tune the desired properties. Here we report the synthesis of selenium substitutionally doped molybdenum disulfide atomic layers, with a broad range of selenium concentrations, resulting in band gap modulations of over 0.2 eV. Atomic scale chemical analysis using Z-contrast imaging provides direct maps of the dopant atom distribution in individual MoS2 layers and hence a measure of the local band gaps. Furthermore, in a bilayer structure, the dopant distribution of each layer is imaged independently. We demonstrate that each layer in the bilayer contains similar doping levels, randomly distributed, providing new insights into the growth mechanism and alloying behavior in two-dimensional dichalcogenide atomic layers. The results show that growth of uniform, ternary, two-dimensional dichalcogenide alloy films with tunable electronic properties is feasible.

  20. II-VI semiconductor compounds

    CERN Document Server

    1993-01-01

    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  1. Electrochemical reactions of organosilicon compounds

    Science.gov (United States)

    Jouikov, Vyacheslav V.

    1997-06-01

    Data on the processes of electrochemical reduction and oxidation of organosilicon compounds of various classes as well as on the interaction of these compounds with electrically generated reagents are generalised and surveyed systematically. The electrochemical reactivity of organic derivatives of silicon is considered taking into account their structures and reaction conditions. The bibliography includes 245 references.

  2. Testing of Experimental Antileishmanial Compounds.

    Science.gov (United States)

    1994-10-19

    administrative and clerical assistance and Ms. Barbara L. Harris, Laboratory Technician II, for technical assistance with this study. Their efforts are appreciated...braziliensis) leishmaniasis . Although several new compounds have been identified with activity against L. (V.) braziliensis, none have shown adequate promise...to warrant initiation of clinical trials. However, among the most promising active compounds found against visceral leishmaniasis during these

  3. Cytotoxic Compounds from Zanthoxylum Americanum

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Four pyranocoumarins: dipetaline, alloxanthoxyletin, xanthoxyletin, and xanthyletin, and two lignans: sesamin and asarinin were isolated from the northern prickly ash, Zanthoxylum americanum. To varying degrees, all six compounds inhibited the incorporation of tritiated thymidine into human leukemia (HL-60) cells and the inhibitory effect was dependent on the structures of the isolated compounds.

  4. Process for demethylating dimethylsulfonium compounds

    NARCIS (Netherlands)

    Hansen, Theo; van der Maarel, Marc

    1998-01-01

    PCT No. PCT/EP94/01640 Sec. 371 Date Nov. 14, 1995 Sec. 102(e) Date Nov. 14, 1995 PCT Filed May 16, 1994 PCT Pub. No. WO94/26918 PCT Pub. Date Nov. 24, 1994Process for preparing S-methylmercapto and mercapto compounds comprising the step of demethylating a dimethylsulfonium compound of formula I to

  5. Assimilation of Unusual Carbon Compounds

    Science.gov (United States)

    Middelhoven, Wouter J.

    Yeast taxa traditionally are distinguished by growth tests on several sugars and organic acids. During the last decades it became apparent that many yeast species assimilate a much greater variety of naturally occurring carbon compounds as sole source of carbon and energy. These abilities are indicative of a greater role of yeasts in the carbon cycle than previously assumed. Especially in acidic soils and other habitats, yeasts may play a role in the degradation of carbon compounds. Such compounds include purines like uric acid and adenine, aliphatic amines, diamines and hydroxyamines, phenolics and other benzene compounds and polysaccharides. Assimilation of purines and amines is a feature of many ascomycetes and basidiomycetes. However, benzene compounds are degraded by only a few ascomycetous yeasts (e.g. the Stephanoascus/ Blastobotrys clade and black yeastlike fungi) but by many basidiomycetes, e.g. Filobasidiales, Trichosporonales, red yeasts producing ballistoconidia and related species, but not by Tremellales. Assimilation of polysaccharides is wide-spread among basidiomycetes

  6. Bilayer Effects of Antimalarial Compounds.

    Directory of Open Access Journals (Sweden)

    Nicole B Ramsey

    Full Text Available Because of the perpetual development of resistance to current therapies for malaria, the Medicines for Malaria Venture developed the Malaria Box to facilitate the drug development process. We tested the 80 most potent compounds from the box for bilayer-mediated effects on membrane protein conformational changes (a measure of likely toxicity in a gramicidin-based stopped flow fluorescence assay. Among the Malaria Box compounds tested, four compounds altered membrane properties (p< 0.05; MMV007384 stood out as a potent bilayer-perturbing compound that is toxic in many cell-based assays, suggesting that testing for membrane perturbation could help identify toxic compounds. In any case, MMV007384 should be approached with caution, if at all.

  7. Complex chemistry with complex compounds

    Directory of Open Access Journals (Sweden)

    Eichler Robert

    2016-01-01

    Full Text Available In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the investigation of fragile single molecular species by gas-phase chromatography. The latest success with the heaviest group 6 transactinide seaborgium is highlighted. The formation of a very volatile hexacarbonyl compound Sg(CO6 was observed similarly to its lighter homologues molybdenum and tungsten. The interactions of these gaseous carbonyl complex compounds with quartz surfaces were investigated by thermochromatography. Second-generation experiments are under way to investigate the intramolecular bond between the central metal atom of the complexes and the ligands addressing the influence of relativistic effects in the heaviest compounds. Our contribution comprises some aspects of the ongoing challenging experiments as well as an outlook towards other interesting compounds related to volatile complex compounds in the gas phase.

  8. Nitrogen removal from urban stormwater runoff through layered bioretention columns.

    Science.gov (United States)

    Hsieh, Chi-hsu; Davis, Allen P; Needelman, Brian A

    2007-11-01

    Bioretention is a low-impact technology used for the treatment of stormwater runoff in developed areas. The fates of mineral nitrogen compounds in two bioretention columns (RP1 and RP2) with different media-layering characteristics were investigated under multiple loadings of simulated urban runoff. The immediate capture of nitrogen was evaluated, with nitrogen transformation reactions that occurred during the drying periods between rainfall events. A greater proportion of ammonium was removed from runoff in RP2 (68 +/- 16%), which had a high permeability layer over a lower permeability layer, than in RP1 (12 +/- 6%), which had the inverse configuration. Both column systems demonstrated nitrate export (9 +/- 32% and 54 +/- 22% greater than input for RP1 and RP2, respectively), attributed to washout of nitrate resulting from nitrification processes between runoff loading events. Bioretention media with a less permeable bottom soil layer could form an anoxic/anaerobic zone for promoting nitrification/denitrification processes.

  9. Spectroscopic infrared ellipsometry to determine the structure of layered samples

    Energy Technology Data Exchange (ETDEWEB)

    Korte, Ernst-Heiner; Hinrichs, Karsten; Roeseler, Arnulf

    2002-10-15

    This contribution outlines investigations in our laboratory in the course of developing spectroscopic infrared ellipsometry into an analytical tool for structure elucidation of a given solid sample with one single experimental technique. The term 'structure' is meant here to comprise the layer or stack geometry of a sample along with the thicknesses, as well as the optical properties of the individual layers. The latter ones--expressed as optical constants--serve as a basis to characterize the layer material, from the identity of the compound to specific molecular interactions and order. There are no general restrictions as to the physical properties of the materials; the individual layers or films should advantageously be thin enough to transmit infrared radiation at least within spectral windows. The sensitivity of infrared ellipsometry to films as thin as a few nanometers or less is illustrated by experimental examples.

  10. Modern Thin-Layer Chromatography.

    Science.gov (United States)

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  11. Modern Thin-Layer Chromatography.

    Science.gov (United States)

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  12. Diversity in S-layers.

    Science.gov (United States)

    Zhu, Chaohua; Guo, Gang; Ma, Qiqi; Zhang, Fengjuan; Ma, Funing; Liu, Jianping; Xiao, Dao; Yang, Xiaolin; Sun, Ming

    2017-01-01

    Surface layers, referred simply as S-layers, are the two-dimensional crystalline arrays of protein or glycoprotein subunits on cell surface. They are one of the most common outermost envelope components observed in prokaryotic organisms (Archaea and Bacteria). Over the past decades, S-layers have become an issue of increasing interest due to their ubiquitousness, special features and functions. Substantial work in this field provides evidences of an enormous diversity in S-layers. This paper reviews and illustrates the diversity from several different aspects, involving the S-layer-carrying strains, the structure of S-layers, the S-layer proteins and genes, as well as the functions of S-layers.

  13. Performance analysis of STT-RAM with cross shaped free layer using Heusler alloys

    Science.gov (United States)

    Bharat Kumary, Tangudu; Ghosh, Bahniman; Awadhiya, Bhaskar; Verma, Ankit Kumar

    2016-01-01

    We have investigated the performance of a spin transfer torque random access memory (STT-RAM) cell with a cross shaped Heusler compound based free layer using micromagnetic simulations. We have designed a free layer using a Cobalt based Heusler compound. Simulation results clearly show that the switching time from one state to the other state has been reduced, also it has been found that the critical switching current density (to switch the magnetization of the free layer of the STT RAM cell) is reduced.

  14. Protecting the ozone layer.

    Science.gov (United States)

    Munasinghe, M; King, K

    1992-06-01

    Stratospheric ozone layer depletion has been recognized as a problem by the Vienna Convention for the Protection of the Ozone Layer and the 1987 Montreal Protocol (MP). The ozone layer shields the earth from harmful ultraviolet radiation (UV-B), which is more pronounced at the poles and around the equator. Industrialized countries have contributed significantly to the problem by releasing chlorofluorocarbons (CFCs) and halons into the atmosphere. The effect of these chemicals, which were known for their inertness, nonflammability, and nontoxicity, was discovered in 1874. Action to deal with the effects of CFCs and halons was initiated in 1985 in a 49-nation UN meeting. 21 nations signed a protocol limiting ozone depleting substances (ODS): CFCs and halons. Schedules were set based on each country's use in 1986; the target phaseout was set for the year 2000. The MP restricts trade in ODSs and weights the impact of substances to reflect the extent of damage; i.e., halons are 10 times more damaging than CFCs. ODS requirements for developing countries were eased to accommodate scarce resources and the small fraction of ODS emissions. An Interim Multilateral Fund under the Montreal Protocol (IMFMP) was established to provide loans to finance the costs to developing countries in meeting global environmental requirements. The IMFMP is administered by the World Bank, the UN Environmental Program, and the UN Development Program. Financing is available to eligible countries who use .3 kg of ODS/person/year. Rapid phaseout in developed countries has occurred due to strong support from industry and a lower than expected cost. Although there are clear advantages to rapid phaseout, there were no incentives included in the MP for rapid phaseout. Some of the difficulties occur because the schedules set minimum targets at the lowest possible cost. Also, costs cannot be minimized by a country-specific and ODS-specific process. The ways to improve implementation in scheduling and

  15. Cooperating systems: Layered MAS

    Science.gov (United States)

    Rochowiak, Daniel

    1990-01-01

    Distributed intelligent systems can be distinguished by the models that they use. The model developed focuses on layered multiagent system conceived of as a bureaucracy in which a distributed data base serves as a central means of communication. The various generic bureaus of such a system is described and a basic vocabulary for such systems is presented. In presenting the bureaus and vocabularies, special attention is given to the sorts of reasonings that are appropriate. A bureaucratic model has a hierarchy of master system and work group that organizes E agents and B agents. The master system provides the administrative services and support facilities for the work groups.

  16. Acoustic transmission through compound subwavelength slit arrays

    Science.gov (United States)

    Ward, G. P.; Hibbins, A. P.; Sambles, J. R.; Smith, J. D.

    2016-07-01

    The angular dependence of the transmission of sound in air through four types of two-dimensional slit arrays formed of aluminium slats is explored, both experimentally and numerically. For a simple, subwavelength periodic slit array, it is well known that Fabry-Perot-like waveguide resonances, supported by the slit cavities, coupled to diffracted evanescent waves, result in enhanced acoustic transmission at frequencies determined by the length, width, and separation of each slit cavity. We demonstrate that altering the spacing or width of some of the slits to form a compound array (i.e., an array having a basis comprised of more than one slit) results in sharp dips in the transmission spectra, which may have a strong angular dependence. These features correspond to phase resonances, which have been studied extensively in the electromagnetic case. This geometry allows for additional near-field configurations compared to the simple array, whereby the field in adjacent cavities can be out of phase. Several types of compound slit arrays are investigated; one such structure is optimized to minimize the effect of boundary-layer loss mechanisms present in each slit cavity, thereby achieving a deep, sharp transmission minimum in a broad maximum.

  17. Estimation of volatile organic compound emissions for Europe using data assimilation

    Directory of Open Access Journals (Sweden)

    M. R. Koohkan

    2013-06-01

    Full Text Available The emissions of non-methane volatile organic compounds (VOCs over western Europe for the year 2005 are estimated via inverse modelling by assimilation of in situ observations of concentration and then subsequently compared to a standard emission inventory. The study focuses on 15 VOC species: five aromatics, six alkanes, two alkenes, one alkyne and one biogenic diene. The inversion relies on a validated fast adjoint of the chemical transport model used to simulate the fate and transport of these VOCs. The assimilated ground-based measurements over Europe are provided by the European Monitoring and Evaluation Programme (EMEP network. The background emission errors and the prior observational errors are estimated by maximum-likelihood approaches. The positivity assumption on the VOC emission fluxes is pivotal for a successful inversion, and this maximum-likelihood approach consistently accounts for the positivity of the fluxes. For most species, the retrieved emissions lead to a significant reduction of the bias, which underlines the misfit between the standard inventories and the observed concentrations. The results are validated through a forecast test and a cross-validation test. An estimation of the posterior uncertainty is also provided. It is shown that the statistically consistent non-Gaussian approach based on a reliable estimation of the errors offers the best performance. The efficiency in correcting the inventory depends on the lifetime of the VOCs and the accuracy of the boundary conditions. In particular, it is shown that the use of in situ observations using a sparse monitoring network to estimate emissions of isoprene is inadequate because its short chemical lifetime significantly limits the spatial radius of influence of the monitoring data. For species with a longer lifetime (a few days, successful, albeit partial, emission corrections can reach regions hundreds of kilometres away from the stations. Domain-wide corrections of the

  18. Basis reduction for layered lattices

    NARCIS (Netherlands)

    Torreão Dassen, Erwin

    2011-01-01

    We develop the theory of layered Euclidean spaces and layered lattices. We present algorithms to compute both Gram-Schmidt and reduced bases in this generalized setting. A layered lattice can be seen as lattices where certain directions have infinite weight. It can also be interpre

  19. TLC analysis of some phenolic compounds in kombucha beverage

    Directory of Open Access Journals (Sweden)

    Malbaša Radomir V.

    2004-01-01

    Full Text Available Black and green tea contains a wide range of natural phenolic compounds Flavanoids and their glycosides, catechins and the products of their condensation, and phenolic acids are the most important. Kombucha beverage is obtained by fermentation of tea fungus on black or green tea sweetened with sucrose. The aim of this paper was to investigate the composition of some phenolic compounds, catechin, epicatechin, quercetin, myricetin, gallic and tanic acid, and monitoring of their status during tea fungus fermentation. The method used for this study was thin layer chromatography with two different systems. The main phenolic compounds in the samples with green tea were catechin and epicatechin, and in the samples with black tea it was quercetin.

  20. Vapor phase adsorption of organic compounds on octyl silicas

    Science.gov (United States)

    Roshchina, T. M.; Shoniya, N. K.; Tayakina, O. Ya.; Fadeev, A. Y.

    2011-02-01

    The influence of the modification of silica by octyltrichlorosilane with the formation of an oligomeric grafted layer (sample C8(II)) and additional silanization (sample C8(III)) on the thermodynamic adsorption characteristics (TACs) of different classes of organic compounds was investigated by gas chromatography. It was shown that the modification leads to decreased adsorption values for most of the investigated compounds (with the exception of alkanes, for which TACs on sample C8(II) approach the values observed on the initial support, due probably to additional interactions with silanol groups formed in modifying the surface with octyltrichlorosilane). It was established that blocking these silanol groups during additional silanization with trimethylsilane resulted in inert surfaces whose adsorption properties with respect to many compounds (including some capable of participating in strong specific interactions) approaches to the properties of octyl-silica with a close-packed grafted monolayer.

  1. Organic compounds in atmospheric aerosols from a Finnish coniferous forest

    Energy Technology Data Exchange (ETDEWEB)

    Anttila, P.; Rissanen, T.; Shimmo, M.; Kallio, M.; Hyoetylaeinen, T.; Riekkola, M.L. [Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki (Finland); Kulmala, M. [Department of Physical Sciences, University of Helsinki (Finland)

    2005-07-01

    Atmospheric aerosol particles were collected with a high-volume sampler in a Finnish coniferous forest during the field campaign Quantification of Aerosol Nucleation in the European Boundary Layer (QUEST) in March-April 2003. Four chromatographic techniques were applied to characterise the organic composition of the samples, and to study variations in the concentrations of identified compounds. Among the nearly 160 organic compounds identified were n-alkanes, nalkanals, n-alkan-2-ones, n- alkanols, n-alkanoic acids, n-alkenoic acids, dicarboxylic acids, polyaromatic hydrocarbons, hopanes, streranes, terpenes and terpenoids. The observed variations in the concentrations of certain compounds were mostly explained by ambient temperature. Comparison of days when atmospheric new particle formation took place with days when the formation did not occur, however, revealed higher concentrations of long-chain n- alkanes (> C{sub 22}) and < C{sub 18} n-alkanoic acids on the particle formation days. (orig.)

  2. The Boundary Layer Radiometer

    Science.gov (United States)

    Irshad, Ranah; Bowles, N. E.; Calcutt, S. B.; Hurley, J.

    2010-10-01

    The Boundary Layer Radiometer is a small, low mass (<1kg) radiometer with only a single moving part - a scan/calibration mirror. The instrument consists of a three mirror telescope system incorporating an intermediate focus for use with miniature infrared and visible filters. It also has an integrated low power blackbody calibration target to provide long-term calibration stability The instrument may be used as an upward looking boundary layer radiometer for both the terrestrial and Martian atmospheres with appropriate filters for the mid-infrared carbon dioxide band, as well as a visible channel for the detection of aerosol components such as dust. The scan mirror may be used to step through different positions from the local horizon to the zenith, allowing the vertical temperature profile of the atmosphere to be retrieved. The radiometer uses miniature infrared filter assemblies developed for previous space-based instruments by Oxford, Cardiff and Reading Universities. The intermediate focus allows for the use of upstream blocking filters and baffles, which not only simplifies the design of the filters and focal plane assembly, but also reduces the risk of problems due to stray light. Combined with the calibration target this means it has significant advantages over previous generations of small radiometers.

  3. Multiresonant layered plasmonic films

    Energy Technology Data Exchange (ETDEWEB)

    DeVetter, Brent M. [Pacific Northwest National Laboratory, Richland, Washington, United States; Bernacki, Bruce E. [Pacific Northwest National Laboratory, Richland, Washington, United States; Bennett, Wendy D. [Pacific Northwest National Laboratory, Richland, Washington, United States; Schemer-Kohrn, Alan [Pacific Northwest National Laboratory, Richland, Washington, United States; Alvine, Kyle J. [Pacific Northwest National Laboratory, Richland, Washington, United States

    2017-01-01

    Multi-resonant nanoplasmonic films have numerous applications in areas such as nonlinear optics, sensing, and tamper indication. While techniques such as focused ion beam milling and electron beam lithography can produce high-quality multi-resonant films, these techniques are expensive, serial processes that are difficult to scale at the manufacturing level. Here, we present the fabrication of multi-resonant nanoplasmonic films using a layered stacking technique. Periodically-spaced gold nanocup substrates were fabricated using self-assembled polystyrene nanospheres followed by oxygen plasma etching and metal deposition via magnetron sputter coating. By adjusting etch parameters and initial nanosphere size, it was possible to achieve an optical response ranging from the visible to the near-infrared. Singly resonant, flexible films were first made by performing peel-off using an adhesive-coated polyolefin film. Through stacking layers of the nanofilm, we demonstrate fabrication of multi-resonant films at a fraction of the cost and effort as compared to top-down lithographic techniques.

  4. Layered kagome spin ice

    Science.gov (United States)

    Hamp, James; Dutton, Sian; Mourigal, Martin; Mukherjee, Paromita; Paddison, Joseph; Ong, Harapan; Castelnovo, Claudio

    Spin ice materials provide a rare instance of emergent gauge symmetry and fractionalisation in three dimensions: the effective degrees of freedom of the system are emergent magnetic monopoles, and the extensively many `ice rule' ground states are those devoid of monopole excitations. Two-dimensional (kagome) analogues of spin ice have also been shown to display a similarly rich behaviour. In kagome ice however the ground-state `ice rule' condition implies the presence everywhere of magnetic charges. As temperature is lowered, an Ising transition occurs to a charge-ordered state, which can be mapped to a dimer covering of the dual honeycomb lattice. A second transition, of Kosterlitz-Thouless or three-state Potts type, occurs to a spin-ordered state at yet lower temperatures, due to small residual energy differences between charge-ordered states. Inspired by recent experimental capabilities in growing spin ice samples with selective (layered) substitution of non-magnetic ions, in this work we investigate the fate of the two ordering transitions when individual kagome layers are brought together to form a three-dimensional pyrochlore structure coupled by long range dipolar interactions. We also consider the response to substitutional disorder and applied magnetic fields.

  5. Membrane rejection of nitrogen compounds

    Science.gov (United States)

    Lee, S.; Lueptow, R. M.

    2001-01-01

    Rejection characteristics of nitrogen compounds were examined for reverse osmosis, nanofiltration, and low-pressure reverse osmosis membranes. The rejection of nitrogen compounds is explained by integrating experimental results with calculations using the extended Nernst-Planck model coupled with a steric hindrance model. The molecular weight and chemical structure of nitrogen compounds appear to be less important in determining rejection than electrostatic properties. The rejection is greatest when the Donnan potential exceeds 0.05 V or when the ratio of the solute radius to the pore radius is greater than 0.8. The transport of solute in the pore is dominated by diffusion, although convective transport is significant for organic nitrogen compounds. Electromigration contributes negligibly to the overall solute transport in the membrane. Urea, a small organic compound, has lower rejection than ionic compounds such as ammonium, nitrate, and nitrite, indicating the critical role of electrostatic interaction in rejection. This suggests that better treatment efficiency for organic nitrogen compounds can be obtained after ammonification of urea.

  6. Application of DLTS method to investigation of deep defect centers in epitaxial layers of multicomponent A{sup III}-B{sup V} compounds; Zastosowanie metody DLTS do badania glebokich centrow defektowych w warstwach epitaxialnych wieloskladnikowych zwiazkow A{sup III}-B{sup V}

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, R.; Kaminski, P. [Instytut Technologii Materialow Elektronicznych, Warsaw (Poland)

    1998-12-31

    The DLTS technique was employed to study deep defect centers in Si doped epitaxial layers of Al{sub 0.37}Ga{sub 0.16}In{sub 0.47}P grown by MOCVD as a part of epitaxial structure GaAs/AlGaInP/GaAs on GaAs substrates. A high concentration of DX centers located in a region near the inverted interface GaAs/Al{sub 0.37}Ga{sub 0.16}In{sub 0.47}P was found. The width of this region with the maximum DX center concentration ranges from 5 to 20 nm. By filling the DX centers in the whole region, the activation energy for electron emission was found to be 0.48 eV. However, it is shown for the first time, that the activation energy of the DX center increases with increasing the distance from the GaAs/Al{sub 0.37}Ga{sub 0.16}In{sub 0.47}P inverted interface. A nonuniform of the DX center concentration on the wafers is also observed. The concentration varies in the range of 1{center_dot}10{sup 17} cm{sup -3} - 10{sup 18} cm{sup -3}. (author) 9 refs, 18 figs

  7. Reversible layer-by-layer deposition on solid substrates inspired by mussel byssus cuticle.

    Science.gov (United States)

    Kim, Suyeob; Kim, Dong Soo; Kang, Sung Min

    2014-01-01

    The protective coating on mussel (Mytilus galloprovincialis) byssus has attracted considerable research interest because of its excellent mechanical properties such as hardness and extensibility. These special properties are known to be highly related with specific interactions between mussel foot protein-1 and metal ions. In particular, the complexation between catechols in mfp-1 and iron(III) has been identified as a key interaction. This finding has given opportunities for pursuing promising applications. Herein, we report that emulating the properties of the mussel byssus cuticle provides an important platform for developing reversible layer-by-layer (LbL) deposition, an advanced technique for surface modification. LbL films were constructed on solid substrates by sequential immersion of substrates into solutions containing iron(III) and catecholic compounds. The thickness of the LbL films was effectively controlled by increasing the immersion steps, and the reversibility of the LbL deposition was demonstrated by addition of a chelating agent.

  8. Methods for improved growth of group III nitride semiconductor compounds

    Energy Technology Data Exchange (ETDEWEB)

    Melnik, Yuriy; Chen, Lu; Kojiri, Hidehiro

    2015-03-17

    Methods are disclosed for growing group III-nitride semiconductor compounds with advanced buffer layer technique. In an embodiment, a method includes providing a suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. The method includes forming an AlN buffer layer by flowing an ammonia gas into a growth zone of the processing chamber, flowing an aluminum halide containing precursor to the growth zone and at the same time flowing additional hydrogen halide or halogen gas into the growth zone of the processing chamber. The additional hydrogen halide or halogen gas that is flowed into the growth zone during buffer layer deposition suppresses homogeneous AlN particle formation. The hydrogen halide or halogen gas may continue flowing for a time period while the flow of the aluminum halide containing precursor is turned off.

  9. The demise of compound houses

    DEFF Research Database (Denmark)

    Andreasen, Jørgen; Eskemose Andersen, Jørgen

    2006-01-01

    and the neighbourhood unity is a challenge for urban planners. However they represent good value for money, cost little to build, suit traditional inheritence patterns, allow independent life at low cost and allow sharing of services with a finite and known group (albeit within a potential conflictive domain). Compound...... of compound housing and analyses the advantages and disadvantages of life within such housing in Kumasi. Issues of privacy, image and communal life are usually cited by occupants dissatiesfied with life in compound houses, and the difficulty of extending them without spoiling the open spaces...

  10. Polishing compound for plastic surfaces

    Science.gov (United States)

    Stowell, Michael S.

    1995-01-01

    A polishing compound for plastic surfaces. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS.TM., LEXAN.TM., LUCITE.TM., polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  11. Polishing compound for plastic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Stowell, M.S.

    1993-01-01

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains colloidal silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{sup TM}, LEXAN{sup TM}, LUCITE{sup TM}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  12. Layer-by-layer assembly of partially sulfonated isotactic polystyrene with poly(vinylamine).

    Science.gov (United States)

    Ajiro, Hiroharu; Beckerle, Klaus; Okuda, Jun; Akashi, Mitsuru

    2012-03-27

    The stereoregular synthetic polymer isotactic polystyrene bearing partially sulfonated groups (SiPS) was used as a layer-by-layer assembled thin film for the first time. When a low molecular weight compound was employed as the pair for the alternative layer-by-layer (LbL) assembly, the frequency shift was very small using quartz crystal microbalance (QCM) analysis, whereas poly(vinylamine) (PVAm) formed an effective pair for the construction of LbL films with SiPS. When it was neutralized, SiPS was not assembled, probably due to the loss of effective polymer-polymer interactions. The ionic strength conditions revealed a slight difference of the assembly behavior on the isotactic polymer as compared to the atactic one. The assembled LbL film showed the same peaks over the range from 1141 to 1227 cm(-1) and 700 cm(-1) in the FT-IR/ATR spectra as the bulk complex of SiPS/PVAm, and the thickness on one side was calculated at 76 nm by QCM analysis. The surface roughness of the film was also observed by AFM.

  13. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  14. The Adobe Photoshop layers book

    CERN Document Server

    Lynch, Richard

    2011-01-01

    Layers are the building blocks for working in Photoshop. With the correct use of the Layers Tool, you can edit individual components of your images nondestructively to ensure that your end result is a combination of the best parts of your work. Despite how important it is for successful Photoshop work, the Layers Tool is one of the most often misused and misunderstood features within this powerful software program. This book will show you absolutely everything you need to know to work with layers, including how to use masks, blending, modes and layer management. You'll learn professional tech

  15. Metal deposition using seed layers

    Science.gov (United States)

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  16. In depth study of molybdenum silicon compound formation at buried interfaces

    Science.gov (United States)

    Zoethout, Erwin; Louis, Eric; Bijkerk, Fred

    2016-09-01

    Angle resolved x-ray photoelectron spectroscopy (ARXPS) has been employed to determine non-destructively the in-depth interface formation during thin film growth. Buried interfaces underneath the nanometer thick layers are probed by identifying the chemical shift of compound materials in photoelectron spectroscopy and using the angular response to quantify the compound amounts from the measured intensities. The thin interfaces in molybdenum-silicon multilayers grown at ambient temperature are investigated. This system is an example of an almost perfect 1D-system, where the interface region is only a small part of the individual layer thicknesses of 3 to 5 nm. Despite the low growth temperature, both the interfaces of this multilayer show layer thickness dependent interface formation. While the silicon-on-molybdenum interface shows a limited interface thickness of 0.4 nm of Mo5Si3, the molybdenum-on-silicon interface shows a more complex evolution. For this interface, the composition of the first 2.0 nm of deposited layer thickness is best described as a molybdenum-silicon compound layer with a molybdenum rich top and a MoSi2 bottom layer. After 2.5 nm of the deposited layer thickness, the molybdenum rich compound at the top has transformed into polycrystalline molybdenum on top of 1.8 nm MoSi2 at the interface. The formation of the 1.8 nm MoSi2 precedes the formation of polycrystalline molybdenum on top. Angle resolved x-ray photoelectron spectroscopy (ARXPS) is shown to be a good tool to study the interface phenomena beneath the nanometer thick top layers. In the case of Mo/Si multilayer mirrors, this ARXPS study shows that the compound formation at the interface accounts for the majority of the extreme ultraviolet reflectance loss.

  17. A previously unreported type of seismic source in the firn layer of the East Antarctic Ice Sheet

    Science.gov (United States)

    Lough, Amanda C.; Barcheck, C. Grace; Wiens, Douglas A.; Nyblade, Andrew; Anandakrishnan, Sridhar

    2015-11-01

    We identify a unique type of seismic source in the uppermost part of the East Antarctic Ice Sheet recorded by temporary broadband seismic arrays in East Antarctica. These sources, termed "firnquakes," are characterized by dispersed surface wave trains with frequencies of 1-10 Hz detectable at distances up to 1000 km. Events show strong dispersed Rayleigh wave trains and an absence of observable body wave arrivals; most events also show weaker Love waves. Initial events were discovered by standard detection schemes; additional events were then detected with a correlation scanner using the initial arrivals as templates. We locate sources by determining the L2 misfit for a grid of potential source locations using Rayleigh wave arrival times and polarization directions. We then perform a multiple-filter analysis to calculate the Rayleigh wave group velocity dispersion and invert the group velocity for shear velocity structure. The resulting velocity structure is used as an input model to calculate synthetic seismograms. Inverting the dispersion curves yields ice velocity structures consistent with a low-velocity firn layer ~100 m thick and show that velocity structure is laterally variable. The absence of observable body wave phases and the relative amplitudes of Rayleigh waves and noise constrain the source depth to be less than 20 m. The presence of Love waves for most events suggests the source is not isotropic. We propose the events are linked to the formation of small crevasses in the firn, and several events correlate with shallow crevasse fields mapped in satellite imagery.

  18. Structural variations in layered alkaline earth metal cyclohexyl phosphonates

    Indian Academy of Sciences (India)

    Ramaswamy Murugavel; Nayanmoni Gogoi

    2009-06-01

    Two series of alkaline earth metal cyclohexyl phosphonates, M(C6H11PO3H)2(H2O) (M = Ca, Sr and Ba) (1–3) and M(C6H11PO3)(H2O) (M = Mg, Ca, Sr, and Ba) (4–7) have been synthesized under mild reaction conditions. All new compounds have been characterized using elemental analysis, IR, TGA and powder X-ray diffraction techniques. The molecular structure of compound 2 determined using single crystal X-ray diffraction technique reveals a layered polymeric structure.

  19. The multiple layer solar collector

    Science.gov (United States)

    Kenna, J. P.

    1983-01-01

    An analytical model is developed for obtaining numerical solutions for differential equations describing the performance of separate layers in a multiple layer solar collector. The configurations comprises heat transfer fluid entering at the top of the collector and travelling down through several layers. A black absorber plate prevents reemission of thermal radiation. The overall performance is shown to depend on the number of layers, the heat transfer coefficient across each layer, and the absorption properties of the working fluid. It is found that the multiple layer system has a performance inferior to that of flat plate selective surface collectors. Air gaps insulating adjacent layers do not raise the efficiency enough to overcome the relative deficiency.

  20. The growth of AgGaTe{sub 2} layers on glass substrates with Ag{sub 2}Te buffer layer by closed space sublimation method

    Energy Technology Data Exchange (ETDEWEB)

    Uruno, Aya; Usui, Ayaka; Takeda, Yuji; Inoue, Tomohiro [Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051 (Japan)

    2015-06-15

    The AgGaTe{sub 2} layer growth was performed by the closed space sublimation method on the Mo/glass substrate. The Ag{sub 2}Te buffer layer was inserted between AgGaTe{sub 2} and Mo layers, to improve the quality of grown layers. Crystallographic properties were analyzed by x-ray diffraction (XRD), and the surface morphologies were analyzed by scanning electron microscopy (SEM). The Ag{sub 2}Te layer grown on the Mo/glass exhibited a membrane filter structure from the SEM observation. XRD spectra of layers grown with and without the buffer layer were compared. The AgGaTe{sub 2} layer with the Ag{sub 2}Te buffer layer exhibited peaks originating from AgGaTe{sub 2}, and a very strong diffraction peak of 112 was observed. On the other hand, it was cleared that the layer grown without the buffer layer exhibited no strong peaks associated with AgGaTe{sub 2}, but Ga-Te compounds. From this, crystallographic properties of the AgGaTe{sub 2} layer were drastically improved by the insertion of the Ag{sub 2}Te buffer layer. Moreover, the surface morphology exhibited a smooth surface when the Ag{sub 2}Te buffer layer was inserted. The nucleation site density of AgGaTe{sub 2} was probably increased since the membrane filter structure exhibited numbers of kinks at the edge. Chemical reaction between Ga and Mo was also eliminated. It was cleared that the insertion of the buffer layer and its surface morphology were an important parameter to grow high quality AgGaTe{sub 2} layers. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)