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Sample records for 6-h study period

  1. An evaluation of the cognitive and mood effects of an energy shot over a 6h period in volunteers: a randomized, double-blind, placebo controlled, cross-over study.

    PubMed

    Wesnes, Keith A; Barrett, Marilyn L; Udani, Jay K

    2013-08-01

    Energy drinks are widely available mostly containing glucose, and several have been demonstrated to improve alertness and cognitive function; these effects generally being identified 30-60min after administration. The present study assessed whether an energy shot without carbohydrates would affect major aspects of cognitive function and also mood in volunteers over a 6h time period. This randomized, double-blind, placebo-controlled,crossover study compared the acute effects of the energy shot with a matching placebo in 94 healthy volunteers. Cognitive function was assessed with a widely used set of automated tests of attention and memory. Mood was assessed with the Bond-Lader, Beck Anxiety Index, Beck Depression Index, Chalder Fatigue Scales (CFS), and the POMS. The volunteers were requested to limit their sleep to between 3 and 6h the night before each testing day. Compared to the placebo, the energy shot significantly improved 6 validated composite cognitive function measures from the CDR System as well as self-rated alertness; the benefits on 4 of the cognitive measures still remaining at 6h. The overall effect sizes of the performance improvements were in the small to medium range and thus notable in this field. In conclusion, an energy shot can significantly improve important aspects of cognitive function for up to 6h compared to placebo in partially sleep-deprived healthy volunteers.

  2. Surface birefringence of self-assembly periodic nanostructures induced on 6H-SiC surface by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Song, Juan; Dai, Ye; Tao, Wenjun; Gong, Min; Ma, Guohong; Zhao, Quanzhong; Qiu, Jianrong

    2016-02-01

    In this paper, we report the birefringence effect of surface self-assembly periodic nanostructures induced on 6H-SiC by femtosecond laser irradiation. Birefringence characteristic (e.g. cross-polarized image), measured by cross polarized microscopy, was found to be controlled by both single pulse energy and scanning velocity. Comparing birefringence measurement results of nanostructures and morphology characterization by Scanning electron microscopy, it is shown that ∼200 nm-period deep-subwavelength periodic ripples (DSWR) plays a dominating role in the birefringence effect. Raman spectra show that the change of retardance with pulse energy and scanning velocity is most possibly caused by the thickness variation of DSWR. Finally, a light attenuator based on a single layer of DSWR structure on 6H-SiC surface was constructed and tested by light source of 800 nm to have a tunable attenuating ratio of 69-100%.

  3. Why are [P(C6H5)4](+)N3- and [As(C6H5)4](+)N3- ionic salts and Sb(C6H5)4N3 and Bi(C6H5)4N3 covalent solids? A theoretical study provides an unexpected answer.

    PubMed

    Christe, Karl O; Haiges, Ralf; Boatz, Jerry A; Jenkins, H Donald Brooke; Garner, Edward B; Dixon, David A

    2011-04-18

    A recent crystallographic study has shown that, in the solid state, P(C(6)H(5))(4)N(3) and As(C(6)H(5))(4)N(3) have ionic [M(C(6)H(5))(4)](+)N(3)(-)-type structures, whereas Sb(C(6)H(5))(4)N(3) exists as a pentacoordinated covalent solid. Using the results from density functional theory, lattice energy (VBT) calculations, sublimation energy estimates, and Born-Fajans-Haber cycles, it is shown that the maximum coordination numbers of the central atom M, the lattice energies of the ionic solids, and the sublimation energies of the covalent solids have no or little influence on the nature of the solids. Unexpectedly, the main factor determining whether the covalent or ionic structures are energetically favored is the first ionization potential of [M(C(6)H(5))(4)]. The calculations show that at ambient temperature the ionic structure is favored for P(C(6)H(5))(4)N(3) and the covalent structures are favored for Sb(C(6)H(5))(4)N(3) and Bi(C(6)H(5))(4)N(3), while As(C(6)H(5))(4)N(3) presents a borderline case.

  4. Direct ab initio study of the C6H6 + CH3/C2H5 = C6H5 + CH4/C2H6 reactions

    NASA Astrophysics Data System (ADS)

    Mai, Tam V.-T.; Ratkiewicz, Artur; Duong, Minh v.; Huynh, Lam K.

    2016-02-01

    A kinetic study of the reactions C6H6 + CH3/C2H5 = C6H5 + CH4/C2H6 was carried out in the temperature range of 300-2500 K using high levels of electronic structure theory, namely, CCSD(T)/CBS//BH&HLYP/cc-pVDZ, and canonical variational transition state theory (CVT) with corrections for small curvature tunneling (SCT) and hindered internal rotation (HIR) treatments. It is found that variational effect is not important and both SCT and HIR corrections noticeably affect the rate constants. Being in good agreement with literature data, the calculated results provide solid basis information for the investigation of the polyaromatic hydrocarbon (PAH) + alkyl radical reaction, an important class in combustion and soot formation.

  5. Graphitization of the 6H-SiC( 0 0 0 1 ) surface studied by HREELS

    NASA Astrophysics Data System (ADS)

    Angot, T.; Portail, M.; Forbeaux, I.; Layet, J. M.

    2002-04-01

    By using high-resolution electron energy loss spectroscopy (HREELS), we have studied the vibrational properties of the various 6H-SiC(0 0 0 1) reconstructions, from the Si-rich to the graphitized surface. The 6H-SiC(0 0 0 1)-(3×3) exhibits the Fuchs-Kliewer (FK) optical phonons commonly observed on strongly polar materials. The lowering of the energy width of the elastically reflected electrons with increasing primary energies reveals the coupling of FK with the plasmon that derives from the bulk doping level. No particular modification in the HREELS spectra is observed after preparation of the 6H-SiC(0 0 0 1)-(√3×√3) R30° surface. On the (6√3×6√3) R30° reconstructed surface, the FK phonon modes display both a blue shift and an increased damping factor. In the ultra-violet energy region we observed a loss structure at ≈6 eV whose dispersion relation allows to readily conclude on the presence of a pure graphite layer: it almost perfectly match the dispersion relation measured on highly oriented pyrolitic graphite for the so-called `π-plasmon' arising from the electronic excitation of π- π∗ interband transition.

  6. Study of surface exfoliation on 6H-SiC induced by H2+ implantation

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Li, B. S.

    2017-03-01

    The effect of lattice damage generated by the H2+-implantation on exfoliation efficiency in 6H-SiC wafers is investigated. <0001> 6H-SiC wafers were implanted with 134 keV H2+ ions to ion fluences from 1.5×1016 to 5×1016 H2+ cm-2 and subsequently annealed at temperatures from 973 K to 1373 K. The samples were studied by a combination of optical microscopy and transmission electron microscopy. Only after 1373 K annealing for 15 min, blisters and exfoliation occur on the H2+-implanted sample surface. With increasing the implantation fluences from 1.5×1016 to 3.75×1016 H2+ cm-2, the exfoliation mean size decreases, while the exfoliation density increases. For the highest fluence of 5×1016 H2+ cm-2, seldom exfoliations occur on the sample surface. Microstructure analysis shows that exfoliation efficiency is largely controlled by the H2+-implantation-induced lattice damage. The depth of the microcrack is related to the implantation fluence. The effect of implantation fluence on dislocation loops, platelet nucleation and growth is investigated.

  7. Experimental study of resonance states in {sup 7}H and {sup 6}H

    SciTech Connect

    Caamano, M.; Mittig, W.; Savajols, H.; Demonchy, C. E.; Jurado, B.; Rejmund, F.; Rejmund, M.; Roussel-Chomaz, P.; Gillibert, A.; Obertelli, A.; Lemmon, R.; Wolski, R.

    2008-10-15

    The {sup 7}H and {sup 6}H nuclear systems were investigated via transfer reactions with a {sup 8}He beam at 15.4A MeV impinging in a {sup 12}C target. The experimental setup allowed a complete reconstruction of the reaction kinematics with the MAYA gas detector, based on the active-target concept, where the carbon atoms of the filling isobutane played also the role of reaction target. The {sup 7}H resonance was observed at 0.57{sub -0.21}{sup +0.42} MeV above the {sup 3}H+4n threshold with a width of 0.09{sub -0.06}{sup +0.94} MeV. The {sup 6}H system was formed at 2.91{sub -0.95}{sup +0.85} MeV with a resonance width of 1.52{sub -0.35}{sup +1.77} MeV. These results show the availability of nuclear structure information well outside the bounding limits, resulting in an extraordinary input to improve the present models and understanding of nuclear matter.

  8. Study on formation of step bunching on 6H-SiC (0001) surface by kinetic Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Chen, Xuejiang; Su, Juan

    2016-05-01

    The formation and evolution of step bunching during step-flow growth of 6H-SiC (0001) surfaces were studied by three-dimensional kinetic Monte Carlo (KMC) method and compared with the analytic model based on the theory of Burton-Cabera-Frank (BCF). In the KMC model the crystal lattice was represented by a structured mesh which fixed the position of atoms and interatomic bonding. The events considered in the model were adatoms adsorption and diffusion on the terrace, and adatoms attachment, detachment and interlayer transport at the step edges. In addition, effects of Ehrlich-Schwoebel (ES) barriers at downward step edges and incorporation barriers at upwards step edges were also considered. In order to obtain more elaborate information for the behavior of atoms in the crystal surface, silicon and carbon atoms were treated as the minimal diffusing species. KMC simulation results showed that multiple-height steps were formed on the vicinal surface oriented toward [ 1 1 bar 00 ] or [ 11 2 bar 0 ] directions. And then the formation mechanism of the step bunching was analyzed. Finally, to further analyze the formation processes of step bunching, a one-dimensional BCF analytic model with ES and incorporation barriers was used, and then it was solved numerically. In the BCF model, the periodic boundary conditions (PBC) were applied, and the parameters were corresponded to those used in the KMC model. The evolution character of step bunching was consistent with the results obtained by KMC simulation.

  9. Deep level defect studies in semi-insulating 4H- and 6H-silicon carbide using optical admittance spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Wonwoo

    The objective of this study is to determine the deep vanadium defect levels in semi-insulating 4H- and 6H- silicon carbide using optical admittance spectroscopy. Also infrared spectroscopy and electron paramagnetic resonance spectroscopy are conducted to support the evidence of vanadium donor and acceptor levels obtained from OAS measurements. Vanadium acts as an amphoteric impurity in silicon carbide with a V3+/4+ acceptor level and V4+/5+ donor level. Although the value for the donor level is well established, the V3+/4+ defect level remains controversial. OAS shows that the vanadium donor level is isolated near Ec-1.7 eV, and the vanadium acceptor level is located at Ec-0.75 eV at a cubic site and Ec-0.94 eV at a hexagonal site in 4H-SiC, while the vanadium donor level of 6H-SiC samples is about Ec-1.5 eV. The acceptor levels of 6H-SiC were assigned to Ec-0.67 eV, E c -0.70 eV at two cubic sites, and Ec-0.87 eV at a hexagonal site. IR spectra demonstrated that the signatures of the vanadium V 3+ and V4+ charge states are present in the samples. EPR and photo-induced EPR are used to identify the V3+/4+ and V4+/5+ levels as well as the V3+ and V 4+ charge states. EPR spectra represent both V3+ and V4+ in 4H- and 6H samples consistent with FTIR data. EPR and photo-induced EPR suggest that the va nadium acceptor level is between 0.7 eV and 0.86 eV, while the donor level is near Ec-1.5 eV in 6H-SiC. The donor level of 4H-SiC is located at Ec-1.6 eV. Thus, the data obtained from EPR and FTIR support the assignment of the vanadium defect levels determined by OAS. Vanadium complexes induced by other elements such as titanium, hydrogen, and nitrogen atoms are also observed in OAS spectra and will be discussed in the text.

  10. Tip induced mechanical deformation of epitaxial graphene grown on reconstructed 6H-SiC(0001) surface during scanning tunneling and atomic force microscopy studies

    NASA Astrophysics Data System (ADS)

    Morán Meza, José Antonio; Lubin, Christophe; Thoyer, François; Cousty, Jacques

    2015-06-01

    The structural and mechanical properties of an epitaxial graphene (EG) monolayer thermally grown on top of a 6H-SiC(0001) surface were studied by combined dynamic scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM). Experimental STM, dynamic STM and AFM images of EG on 6H-SiC(0001) show a lattice with a 1.9 nm period corresponding to the (6 × 6) quasi-cell of the SiC surface. The corrugation amplitude of this (6 × 6) quasi-cell, measured from AFM topographies, increases with the setpoint value of the frequency shift Δf (15-20 Hz, repulsive interaction). Excitation variations map obtained simultaneously with the AFM topography shows that larger dissipation values are measured in between the topographical bumps of the (6 × 6) quasi-cell. These results demonstrate that the AFM tip deforms the graphene monolayer. During recording in dynamic STM mode, a frequency shift (Δf) map is obtained in which Δf values range from 41 to 47 Hz (repulsive interaction). As a result, we deduced that the STM tip, also, provokes local mechanical distortions of the graphene monolayer. The origin of these tip-induced distortions is discussed in terms of electronic and mechanical properties of EG on 6H-SiC(0001).

  11. Tip induced mechanical deformation of epitaxial graphene grown on reconstructed 6H-SiC(0001) surface during scanning tunneling and atomic force microscopy studies.

    PubMed

    Meza, José Antonio Morán; Lubin, Christophe; Thoyer, François; Cousty, Jacques

    2015-01-26

    The structural and mechanical properties of an epitaxial graphene (EG) monolayer thermally grown on top of a 6H-SiC(0001) surface were studied by combined dynamic scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM). Experimental STM, dynamic STM and AFM images of EG on 6H-SiC(0001) show a lattice with a 1.9 nm period corresponding to the (6 × 6) quasi-cell of the SiC surface. The corrugation amplitude of this (6 × 6) quasi-cell, measured from AFM topographies, increases with the setpoint value of the frequency shift Δf (15-20 Hz, repulsive interaction). Excitation variations map obtained simultaneously with the AFM topography shows that larger dissipation values are measured in between the topographical bumps of the (6 × 6) quasi-cell. These results demonstrate that the AFM tip deforms the graphene monolayer. During recording in dynamic STM mode, a frequency shift (Δf) map is obtained in which Δf values range from 41 to 47 Hz (repulsive interaction). As a result, we deduced that the STM tip, also, provokes local mechanical distortions of the graphene monolayer. The origin of these tip-induced distortions is discussed in terms of electronic and mechanical properties of EG on 6H-SiC(0001).

  12. Positron lifetime studies on 8 MeV electron-irradiated n-type 6H silicon carbide

    NASA Astrophysics Data System (ADS)

    Lam, C. H.; Lam, T. W.; Ling, C. C.; Fung, S.; Beling, C. D.; De-Sheng, Hang; Huimin, Weng

    2004-11-01

    The positron lifetime technique was employed to study vacancy-type defects in 8 MeV electron-irradiated n-type 6H silicon carbide. A long-lifetime component having a characteristic lifetime of 223-232 ps was observed in the irradiated sample and was attributed to the VCVSi divacancy. Other positron traps, which dominated at low temperatures, were observed to compete with the VCVSi for trapping positrons. A positron trapping model involving a positron shallow trap, a negatively charged monovacancy and the VCVSi divacancy was found to give a good description of the temperature-dependent positron lifetime data of the 1200 °C annealed sample. The identity of the monovacancy could not be unambiguously determined, but its lifetime was found to be in the range 160-172 ps.

  13. UV photoemission study of heteroepitaxial AlGaN films grown on 6H-SiC

    NASA Astrophysics Data System (ADS)

    Benjamin, M. C.; Bremser, M. D.; Weeks, T. W.; King, S. W.; Davis, R. F.; Nemanich, R. J.

    1996-09-01

    This study presents results of UV photoemission measurements of the surface and interface properties of heteroepitaxial AlGaN on 6H-SiC. Previous results have demonstrated a negative electron affinity of AlN on 6H-SiC. In this study Al xGa 1- xN alloy films were grown by organometallic vapor phase epitaxy (OMVPE) and doped with silicon. The analytical techniques included UPS, Auger electron spectroscopy, and LEED. All analysis took place in an integrated UHV transfer system which included the analysis techniques, a surface processing chamber and a gas source MBE. The OMVPE alloy samples were transported in air to the surface characterization system while the AlN and GaN investigations were prepared in situ. The surface electronic states were characterized by surface normal UV photoemission to determine whether the electron affinity was positive or negative. Two aspects of the photoemission distinguish a surface that exhibits a NEA: (1) the spectrum exhibits a sharp peak in the low kinetic energy region, and (2) the width of the spectrum is hv - Eg. The in situ prepared AlN samples exhibited the characteristics of a NEA while the GaN and Al 0.13Ga 0.87N samples did not. The Al 0.55Ga 0.45N sample shows a low positive electron affinity. Annealing of the sample to > 400°C resulted in the disappearance of the sharp emission features, and this effect was related to contaminant effects on the surface. The results suggest the potential of nitride based cold cathode electron emitters.

  14. Deep level transient spectroscopy study of particle irradiation induced defects in n-6H-SiC

    NASA Astrophysics Data System (ADS)

    Chen, X. D.; Gong, M.; Fung, S.; Beling, C. D.; Ling, C. C.

    2004-03-01

    Neutron and electron irradiation induced deep level defects in n-type 6H-SiC have been investigated using deep level transient spectroscopy (DLTS) combined with annealing experiments. Deep levels ED1, E1/E2, Ei, and Z1/Z2 were observed in n-type 6H-SiC material irradiated with neutron. Thermal annealing studies of these deep levels revealed that ED1 and Ei annealed at a temperature below 350^oC, Z1/Z2 levels annealed out at 900^oC, while the intensity of the E1/E2 peaks increased with annealing temperature, reached a maximum at about 500-750^oC, and finally annealed out at 1400^oC. Upon further annealing at 1600^oC, four deep levels labeled NE1 at EC-0.44eV, NE2 EC-0.53eV, NE3 EC-0.64eV, and NE4 EC-0.68eV are produced. Ionization energies of these levels are similar to E1/E2 and Z1/Z2 respectively, but their capture cross sections are different. Samples were irradiated with electrons with different energies ranging from 0.2MeV to 1.7MeV. No deep level was detected in samples irradiated with 0.2MeV electron and deep levels ED1, E1/E2, and Ei were induced with electron energy larger than 0.3MeV.

  15. DEFECT SELECTIVE ETCHING OF THICK ALN LAYERS GROWN ON 6H-SIC SEEDS - A TRANSMISSION ELECTRON MICROSCOPY STUDY

    SciTech Connect

    Nyakiti, Luke; Chaudhari, Jharna; Kenik, Edward A; Lu, Peng; Edgar, J H

    2008-01-01

    In the present study, the type and densities of defects in AlN crystals grown on 6H-SiC seeds by the sublimation-recombination method were assessed. The positions of the defects in AlN were first identified by defect selective etching (DSE) in molten NaOH-KOH at 400 C for 2 minutes. Etching produced pits of three different sizes: 1.77 m, 2.35 m , and 2.86 m. The etch pits were either aligned together forming a sub-grain boundary or randomly distributed. The smaller etch pits were either isolated or associated with larger etch pits. After preparing crosssections of the pits by the focused ion beam (FIB) technique, transmission electron microscopy (TEM) was performed to determine which dislocation type (edge, mixed or screw) produced a specific etch pit sizes. Preliminary TEM bright field and dark field study using different zone axes and diffraction vectors indicates an edge dislocation with a Burgers vector 1/3[1120] is associated with the smallest etch pit size.

  16. Deep level transient spectroscopic study of neutron-irradiated n-type 6H-SiC

    NASA Astrophysics Data System (ADS)

    Chen, X. D.; Fung, S.; Ling, C. C.; Beling, C. D.; Gong, M.

    2003-09-01

    Deep level transient spectroscopy has been employed to study the deep level defects introduced in n-type 6H-SiC after neutron irradiation. Deep levels situated at EC-0.23, EC-0.36/0.44, EC-0.50, and EC-0.62/0.68 eV have been detected in the temperature range of 100-450 K, which have been identified with the previously reported deep levels ED1, E1/E2, Ei, and Z1/Z2, respectively. Thermal annealing studies of these deep levels reveal that ED1 and Ei anneal at a temperature below 350 °C, the Z1/Z2 levels anneal out at 900 °C, while the intensity of the E1/E2 peaks is increased with annealing temperature, reaching a maximum at about 500-750 °C, and finally annealing out at 1400 °C. The possible nature of the deep levels ED1, E1/E2, Ei, and Z1/Z2 are discussed in the context of their annealing behavior. Upon further annealing at 1600 °C, four deep levels labeled NE1 at EC-0.44 eV, NE2 EC-0.53 eV, NE3EC-0.64 eV, and NE4EC-0.68 eV are produced. Evidence is given that these levels are different in their origin to E1/E2 and Z1/Z2.

  17. Insights into Hydrocarbon Chain and Aromatic Ring Formation in the Interstellar Medium: Computational Study of the Isomers of C4H3+ C6H3+ and C6H5+ and Their Formation Pathways

    NASA Astrophysics Data System (ADS)

    Peverati, Roberto; Bera, Partha P.; Lee, Timothy J.; Head-Gordon, Martin

    2016-10-01

    Small hydrocarbons such as acetylene is present in circumstellar envelopes of carbon-rich stars, but the processes that yield larger molecules, and eventually polycyclic aromatic hydrocarbons (PAHs), remain poorly understood. To gain additional insight into the early steps of such processes, electronic structure calculations were performed on the potential energy surfaces of {{{C}}}4{{{{H}}}3}+, {{{C}}}6{{{{H}}}3}+ and {{{C}}}6{{{{H}}}5}+. The results establish reactive pathways from acetylene and its ion to formation of the first aromatic ring. We characterize the stable isomers, their spectroscopic properties, and many of the transition structures that represent barriers to isomerization. The pathways to stabilized {{{C}}}4{{{{H}}}3}+ and {{{C}}}6{{{{H}}}3}+ are most likely to arise from unimolecular decomposition of hot {{{C}}}4{{{{H}}}4}+ and {{{C}}}6{{{{H}}}4}+ by H atom elimination. By contrast, we found an ion-molecule pathway to {{{C}}}6{{{{H}}}5}+ to be very stable to fragmentation and elimination reactions even without collisional stabilization. This aromatic species is a good nucleation center for the growth of larger PAHs in interstellar conditions.

  18. Study of the K2Ni(SO4)2 • 6H2O-K2Co(SO4)2 • 6H2O-H2O diagram and determination of the conditions for growing K2(Ni,Co)(SO4)2 • 6H2O mixed crystals

    NASA Astrophysics Data System (ADS)

    Zhokhov, A. A.; Masalov, V. M.; Zverkova, I. I.; Emelchenko, G. A.; Manomenova, V. L.; Rudneva, E. B.; Vasilieva, N. A.; Voloshin, A. E.

    2016-11-01

    The phase diagram of the K2Ni(SO4)2 · 6H2O-K2Co(SO4)2 · 6H2O-H2O ternary system is investigated in the temperature range of 30-70°C, and a relationship between the compositions of the equilibrium phases of the K2Co x Ni(1- x)(SO4)2 · 6H2O (KCNSH) solid solution and the growth solution is established. It is shown how the salt compositions of the liquid and solid phases change during crystal growth upon slow cooling of solution. A dependence of the lattice parameters of the KCNSH solid solution on the concentration of isomorphic components is experimentally found.

  19. Electronic Spectroscopy of [FePAH](+) Complexes in the Region of the Diffuse Interstellar Bands: Multireference Wave Function Studies on [FeC6H6](+).

    PubMed

    Lanza, Mathieu; Simon, Aude; Ben Amor, Nadia

    2015-06-11

    The low-energy states and electronic spectrum in the near-infrared-visible region of [FeC6H6](+) are studied by theoretical approaches. An exhaustive exploration of the potential energy surface of [FeC6H6](+) is performed using the density functional theory method. The ground state is found to be a (4)A1 state. The structures of the lowest energy states ((4)A2 and (4)A1) are used to perform multireference wave function calculations by means of the multistate complete active space with perturbation at the second order method. Contrary to the density functional theory results ((4)A1 ground state), multireference perturbative calculations show that the (4)A2 state is the ground state. The vertical electronic spectrum is computed and compared with the astronomical diffuse interstellar bands, a set of near-infrared-visible bands detected on the extinction curve in our and other galaxies. Many transitions are found in this domain, corresponding to d → d, d → 4s, or d → π* excitations, but few are allowed and, if they are, their oscillation strengths are small. Even though some band positions could match some of the observed bands, the relative intensities do not fit, making the contribution of the [Fe-C6H6](+) complexes to the diffuse interstellar bands questionable. This work, however, lays the foundation for the studies of polycyclic aromatic hydrocarbons (PAHs) complexed to Fe cations that are more likely to possess d → π* and π → π* transitions in the diffuse interstellar bands domain. PAH ligands indeed possess a larger number of π and π* orbitals, respectively, higher and lower in energy than those of C6H6, which are expected to lead to lower energy d → π* and π → π* transitions in [FePAH](+) than in [FeC6H6](+) complexes.

  20. Theoretical and electron paramagnetic resonance studies of hyperfine interaction in nitrogen doped 4H and 6H SiC

    SciTech Connect

    Szász, K.; Gali, A.

    2014-02-21

    Motivated by recent experimental findings on the hyperfine signal of nitrogen donor (N{sub C}) in 4 H and 6 H SiC, we calculate the hyperfine tensors within the framework of density functional theory. We find that there is negligible hyperfine coupling with {sup 29}Si isotopes when N{sub C} resides at h site both in 4 H and 6 H SiC. We observe measurable hyperfine coupling to a single {sup 29}Si at k site in 4 H SiC and k{sub 1} site in 6 H SiC. Our calculations unravel that such {sup 29}Si hyperfine coupling does not occur at k{sub 2} site in 6 H SiC. Our findings are well corroborated by our new electron paramagnetic resonance studies in nitrogen doped 6 H SiC.

  1. Theoretical study of neutral and charged Fe7-(C6H6)m, m = 1, 2 rice-ball clusters.

    PubMed

    Castro, Miguel; Mareca, Pilar

    2014-07-24

    Bonding of benzene molecules on the surface of neutral and charged Fe7 clusters, which have pentagonal bipyramids (PBP), was studied by means of all-electrons density functional calculations. Dispersion corrections were done with the BPW91-D2 method using the 6-311++G(2d,2p) basis sets. With two less coordinated equatorial sites (bonded to four iron atoms) and one axial site (bonded to five atoms), a triangular face of Fe7 emerges as the basic unit for the absorption of benzene moieties. Bonding of benzene (Bz) on such triangle yields the ground state (GS) for Fe7Bz, Fe7Bz(-), and Fe7Bz(+). Without dispersion, in the GS of Fe7Bz(-), the ligand is η(6) coordinated with a single equatorial iron site, and in the GSs of Fe7Bz2 and Fe7Bz2(-), each benzene moiety is η(6) bonded on opposite equatorial sites. However, BPW91-D2 yields GS structures for Fe7Bz2, Fe7Bz2(-), and Fe7Bz2(+), where the absorption is done on opposite triangles. Therefore, dispersion corrections are crucial for a proper study of Fe7Bz2. The multiplicities (M = 2S + 1, where S is the total spin) of these species, 17, 16, and 18, respectively, are smaller than those of Fe7(23), Fe7(-)(22) and Fe7(+)(24) showing important quenching of the magnetic moment of Fe7. Bond dissociation energies (BDE), in kcal/mol, for Fe7Bz (32.7), Fe7Bz(+) (47.3), and Fe7Bz(-) (27.2) show bigger (smaller) values for the cation (anion). A similar picture was found for the BDEs of Fe7Bz2. Ionization energies, 5.37 and 4.94 eV, for m = 1 and 2 are smaller than that of Fe7, 6.00 eV; which is due to delocalization of the electrons through the network of 3d-π bonds. Electron affinities of Fe7Bz1,2 are also smaller than that of Fe7, being mainly due to the increased repulsion.

  2. Temperature dependent behavior of localized and delocalized electrons in nitrogen-doped 6H SiC crystals as studied by electron spin resonance

    SciTech Connect

    Savchenko, D.; Kalabukhova, E.; Shanina, B.; Kiselov, V.; Cichoň, S.; Honolka, J.; Mokhov, E.

    2016-01-28

    We have studied the temperature behavior of the electron spin resonance (ESR) spectra of nitrogen (N) donors in n-type 6H SiC crystals grown by Lely and sublimation sandwich methods (SSM) with donor concentration of 10{sup 17 }cm{sup −3} at T = 60–150 K. A broad signal in the ESR spectrum was observed at T ≥ 80 K with Lorentzian lineshape and g{sub ||} = 2.0043(3), g{sub ⊥} = 2.0030(3), which was previously assigned in the literature to the N donors in the 1s(E) excited state. Based on the analysis of the ESR lineshape, linewidth and g-tensor we attribute this signal to the conduction electrons (CE). The emergence of the CE ESR signal at T > 80 K was explained by the ionization of electrons from the 1s(A{sub 1}) ground and 1s(E) excited states of N donors to the conduction band while the observed reduction of the hyperfine (hf) splitting for the N{sub k1,k2} donors with the temperature increase is attributed to the motional narrowing effect of the hf splitting. The temperature dependence of CE ESR linewidth is described by an exponential law (Orbach process) with the activation energy corresponding to the energy separation between 1s(A{sub 1}) and 1s(E) energy levels for N residing at quasi-cubic sites (N{sub k1,k2}). The theoretical analysis of the temperature dependence of microwave conductivity measured by the contact-free method shows that due to the different position of the Fermi level in two samples the ionization of free electrons occurs from the energy levels of N{sub k1,k2} donors in Lely grown samples and from the energy level of N{sub h} residing at hexagonal position in 6H SiC grown by SSM.

  3. On the structure and reactivity of small iron clusters with benzene, [Fen-C6H6]0,+,-, n ⩽ 7: A theoretical study

    NASA Astrophysics Data System (ADS)

    Valencia, Israel

    2016-09-01

    The structural, energetic, electronic, vibrational, and magnetic properties of iron-benzene clusters, Fen-C6H6, n ⩽ 7, were calculated using an all-electron density functional theory, DFT, with the generalized gradient approximation and the 6-311++G(2d,2p) basis set. A proposal regarding the mechanism of the adsorption of benzene on iron clusters related to the charge transfer model is described. A direct relation between the calculated electron affinity, EA, of the Fen-C6H6 clusters and their reactivity were also determined.

  4. Molecular dynamics study of congruent melting of the equimolar ionic liquid-benzene inclusion crystal [emim][NTf2]•C6H6

    NASA Astrophysics Data System (ADS)

    Kowsari, M. H.; Alavi, Saman; Ashrafizaadeh, Mahmud; Najafi, Bijan

    2010-01-01

    We use molecular dynamics simulations to study the structure, dynamics, and details of the mechanism of congruent melting of the equimolar mixture of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide with benzene, [emim][NTf2]•C6H6. Changes in the molecular arrangement, radial distribution functions, and the dynamic behavior of species are used to detect the solid to liquid transition, show an indication of the formation of polar islands by aggregating of the ions in the liquid phase, and characterize the melting process. The predicted enthalpy of melting ΔHm=38±2 kJ mol-1 for the equimolar inclusion mixture at 290 K is in good agreement with the differential scanning calorimetry experimental results of 42±2 kJ mol-1. The dynamics of the ions and benzene molecules were studied in the solid and liquid states by calculating the mean-square displacement (MSD) and the orientational autocorrelation function. The MSD plots show strong association between ion pairs of the ionic liquid in the inclusion mixture. Indeed, the presence of a stoichiometric number of benzene molecules does not affect the nearest neighbor ionic association between [emim]+ and [NTf2]-, but increases the MSDs of both cations and anions compared to pure liquid [emim][NTf2], showing that second shell ionic associations are weakened. We monitored the rotational motion of the alkyl chain sides of imidazolium cations and also calculated the activation energy for rotation of benzene molecules about their C6 symmetry axes in their lattice sites prior to melting.

  5. Formation of the phenyl radical [C6H5(X(2)A1)] under single collision conditions: a crossed molecular beam and ab initio study.

    PubMed

    Zhang, Fangtong; Jones, Brant; Maksyutenko, Pavlo; Kaiser, Ralf I; Chin, Christine; Kislov, Vadim V; Mebel, Alexander M

    2010-03-03

    Reactions of dicarbon molecules (C(2)) with C(4)H(6) isomers such as 1,3-butadiene represent a potential, but hitherto unnoticed, route to synthesize the first aromatic C(6) ring in hydrocarbon flames and in the interstellar medium where concentrations of dicarbon transient species are significant. Here, crossed molecular beams experiments of dicarbon molecules in their X(1)Sigma(g)(+) electronic ground state and in the first electronically excited a(3)Pi(u) state have been conducted with 1,3-butadiene and two partially deuterated counterparts (1,1,4,4-D4-1,3-butadiene and 2,3-D2-1,3-butadiene) at two collision energies of 12.7 and 33.7 kJ mol(-1). Combining these scattering experiments with electronic structure and RRKM calculations on the singlet and triplet C(6)H(6) surfaces, our investigation reveals that the aromatic phenyl radical is formed predominantly on the triplet surface via indirect scattering dynamics through a long-lived reaction intermediate. Initiated by a barrierless addition of triplet dicarbon to one of the terminal carbon atoms of 1,3-butadiene, the collision complex undergoes trans-cis isomerization followed by ring closure and hydrogen migration prior to hydrogen atom elimination, ultimately forming the phenyl radical. The latter step emits the hydrogen atom almost perpendicularly to the rotational plane of the decomposing intermediate and almost parallel to the total angular momentum vector. On the singlet surface, smaller contributions of phenyl radical could not be excluded; experiments with partially deuterated 1,3-butadiene indicate the formation of the thermodynamically less stable acyclic H(2)CCHCCCCH(2) isomer. This study presents the very first experimental evidence, contemplated by theoretical studies, that under single collision conditions an aromatic hydrocarbon molecule can be formed in a bimolecular gas-phase reaction via reaction of two acyclic molecules involving cyclization processes at collision energies highly relevant to

  6. Study of defect structures in 6H-SiC a/m-plane pseudofiber crystals grown by hot-wall CVD epitaxy

    DOE PAGES

    Goue, Ouloide Y.; Raghothamachar, Balaji; Yang, Yu; ...

    2015-11-25

    Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match themore » polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed–epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed–homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.« less

  7. Study of defect structures in 6H-SiC a/m-plane pseudofiber crystals grown by hot-wall CVD epitaxy

    SciTech Connect

    Goue, Ouloide Y.; Raghothamachar, Balaji; Yang, Yu; Guo, Jianqiu; Dudley, Michael; Kisslinger, Kim; Trunek, Andrew J.; Neudeck, Philip G.; Spry, David J.; Woodworth, Andrew A.

    2015-11-25

    Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match the polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed–epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed–homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.

  8. Study of the interaction of 4H-SiC and 6H-SiC(0001)Si surfaces with atomic nitrogen

    NASA Astrophysics Data System (ADS)

    Losurdo, Maria; Giangregorio, Maria M.; Bruno, Giovanni; Brown, April; Kim, Tong-Ho

    2004-11-01

    The interaction of atomic nitrogen with 4H- and 6H-SiC(0001) Si-face surfaces is investigated. Clean and atomically smooth terraced surfaces obtained by in situ cleaning using atomic hydrogen have been exposed at 200°C and 750°C to atomic nitrogen produced by a rf remote N2 plasma. Spectroscopic ellipsometry is used for real-time monitoring of the kinetics of SiC surface modifications, and determining the thickness and properties of the nitrided layer. Surface potential measurements reveal the band bending of the nitrided SiC surface. An improvement in the heteroepitaxy of GaN on the low-temperature nitrided SiC surface is found.

  9. High density H2 associative absorption on Titanium alpha-borozene (Ti2B6H6): An ab-initio case study

    NASA Astrophysics Data System (ADS)

    Akbarzadeh, Alireza; Tymzcak, C. J.

    2011-03-01

    Hydrogen is considered as a clean energy carrier that could be a future replacement for our addiction to fossil fuels. However, in order to have hydrogen economy at its highest efficiently we need to store hydrogen at high volumetric and gravimetric density. Using the all electron hybrid density functional theory, we have designed a benzene-like-molecule, Ti2B6H6, which has the promise of achieving this goal. Our results show that the molecule can associatively absorb the hydrogen up to ten percent by weight of hydrogen, which exceeds the 2015 US department of energy target. In this presentation we will discuss the mechanisms of H2 absorption and possible applications of this novel molecule. This research is funded by the Welch Foundation under Grant J. 1675 and the Texas Southern University High Performance Computing Center.

  10. Synthesis, thermal, XRD and spectroscopic studies characterization of Tutton salt K2M (SO4)2·6H2O (M = Mg, Ni)

    NASA Astrophysics Data System (ADS)

    Marzougui, H.; Attia-Essaies, S.; Ben Hassen-Chehimi, D.

    2016-09-01

    Tutton's salts K2M(SO4)2·6H2O (M = Mg, Ni) have been synthesized by the slow evaporation method at room temperature. A complete structural characterization has been carried out by means of powder X-ray diffraction (XRD). The results indicate that the structure of these salts is monoclinic system with the space group P21/a (Z = 2). IR and Raman spectra of KMS6 (M = Mg,Ni) have been recorded and analyzed. From the spectra, the vibrations due to SO42- ion, the complex [M(H2O)6]2+ and the water molecules have been identified. Thermogravimetry, differential thermal analysis and XRD at high-temperature investigations show that the dehydration of these salts occurs between 300 and 500 K. This indicates the removal of all water molecules around 426 K.

  11. Raman and infrared spectroscopic study of synthetic ungemachite, K3Na8Fe(SO4)6(NO3)2·6H2O

    NASA Astrophysics Data System (ADS)

    Vargas Jentzsch, Paul; Ciobotă, Valerian; Bolanz, Ralph Michael; Kampe, Bernd; Rösch, Petra; Majzlan, Juraj; Popp, Jürgen

    2012-08-01

    Iron is an important element usually found in atmospheric particulate matter, and its occurrence can be attributed to both natural and anthropogenic sources. It is an accepted fact that the atmospheric particles interact with water and other atmospheric components, therefore dissolution-crystallization processes can be expected. In this work, considering specially that low pH values are characteristic of aerosol solutions, we postulate that the rare mineral ungemachite, K3Na8Fe(SO4)6(NO3)2·6H2O can crystallize in atmosphere. The Raman and infrared spectra of synthetic ungemachite are presented and the band assignments are proposed and discussed. This is the first time that a synthetic method for ungemachite is reported.

  12. Infrared spectroscopic study of Rb2M(XO4)2·6H2O (M = Mg, Co, Ni, Cu, Zn; X = S, Se) and of SO42- guest ions included in rubidium Tutton selenates

    NASA Astrophysics Data System (ADS)

    Karadjova, V.; Stoilova, D.

    2013-10-01

    The solubility in the three-component systems Rb2SeO4-MSeO4-H2O (M = Mg, Ni, Cu) is studied at 25 °C by the method of isothermal decrease of supersaturation. It has been established that double compounds, Rb2M(SeO4)2·6H2O (M = Mg, Ni, Cu), crystallize from the ternary solutions within wide concentration ranges.

  13. Thermal and X-ray diffraction studies on the phase equilibria in the system UO 2(NO 3) 2 · 6H 2O-NaNO 3

    NASA Astrophysics Data System (ADS)

    Kalekar, B. B.; Rajagopalan, K. V.; Pillai, C. G. S.; Ravindran, P. V.; Mathur, P. K.

    2000-06-01

    The interaction between uranyl nitrate hexahydrate and sodium nitrate at high temperatures has been studied using TG-DTA-EGA, infrared spectral and X-ray diffraction (XRD) measurements. Compound formation in the nitrate system was apparent from the differences in dehydration pattern of the nitrate mixtures as the composition was varied and also from the variation in crystallographic nature of the intermediate compounds formed. The results showed that compound formation was favoured in equimolar mixtures and intermediate nitrates of the type Na[UO 2(NO 3) 3] · H 2O and Na 2[(UO 2NO 3) 2(O) 2] were formed. The latter compound which is essentially a dimerised sodium uranyl oxynitrate has been identified for the first time. XRD, infrared spectral and thermal stability data on this compound have been reported. It decomposes above 435°C to sodium diuranate. When the amount of sodium nitrate in the mixture is less than 50 mol%, the excess uranyl nitrate hexahydrate decomposes to U 3O 8 through the formation of hydroxynitrates of uranium and amorphous UO 3 rather than forming a mixed nitrate or oxide of lower sodium-to-uranium ratio.

  14. Photodissociation of CH{sub 3}Cl, C{sub 2}H{sub 5}Cl, and C{sub 6}H{sub 5}Cl on the Ag(111) surface: Ab initio embedded cluster and configuration interaction study

    SciTech Connect

    Kokh, Daria B.; Liebermann, Heinz-Peter; Buenker, Robert J.

    2010-02-21

    We report a comparative study of the photoinduced C-Cl bond cleavage in three Rd-Cl molecules (Rd=CH{sub 3}, C{sub 2}H{sub 5}, and C{sub 6}H{sub 5} radicals) on the Ag(111) surface. The ground, lowest excited states as well as anion states of adsorbed molecules have been computed at their equilibrium geometry and along the C-Cl dissociation pathway using the ab initio embedded cluster and multireference configuration interaction methods. The anion state can be formed by photoinduced electron transfer from the substrate to an adsorbate and is strongly bound to the surface in contrast with the electronic states of the adsorbate itself, which are only weakly perturbed by the silver surface. The excitation energy of the anion state lies lower in the Franck-Condon region than that of the lowest singlet excited state for all adsorbates and correlates directly with the dissociation products: adsorbed chlorine atom and the gas phase or adsorbed radical for Rd=CH{sub 3}, C{sub 2}H{sub 5}, and C{sub 6}H{sub 5}, respectively. The computed redshift of the photodissociation spectrum for the substrate-mediated photodissociation process relative to the corresponding gas-phase reaction is {approx}2 eV for CH{sub 3}Cl and C{sub 2}H{sub 5}Cl, and {approx}1 eV for C{sub 6}H{sub 5}Cl, which result is in good agreement with experimental data.

  15. A VUV photoionization study of the combustion-relevant reaction of the phenyl radical (C6H5) with propylene (C3H6) in a high temperature chemical reactor.

    PubMed

    Zhang, Fangtong; Kaiser, Ralf I; Golan, Amir; Ahmed, Musahid; Hansen, Nils

    2012-04-12

    We studied the reaction of phenyl radicals (C(6)H(5)) with propylene (C(3)H(6)) exploiting a high temperature chemical reactor under combustion-like conditions (300 Torr, 1200-1500 K). The reaction products were probed in a supersonic beam by utilizing tunable vacuum ultraviolet (VUV) radiation from the Advanced Light Source and recording the photoionization efficiency (PIE) curves at mass-to-charge ratios of m/z = 118 (C(9)H(10)(+)) and m/z = 104 (C(8)H(8)(+)). Our results suggest that the methyl and atomic hydrogen losses are the two major reaction pathways with branching ratios of 86 ± 10% and 14 ± 10%. The isomer distributions were probed by fitting the recorded PIE curves with a linear combination of the PIE curves of the individual C(9)H(10) and C(8)H(8) isomers. Styrene (C(6)H(5)C(2)H(3)) was found to be the exclusive product contributing to m/z = 104 (C(8)H(8)(+)), whereas 3-phenylpropene, cis-1-phenylpropene, and 2-phenylpropene with branching ratios of 96 ± 4%, 3 ± 3%, and 1 ± 1% could account for the signal at m/z = 118 (C(9)H(10)(+)). Although searched for carefully, no evidence of the bicyclic indane molecule could be provided. The reaction mechanisms and branching ratios are explained in terms of electronic structure calculations nicely agreeing with a recent crossed molecular beam study on this system.

  16. A VUV Photoionization Study of the Combustion-Relevant Reaction of the Phenyl Radical (C6H5) with Propylene (C3H6) in a High Temperature Chemical Reactor

    SciTech Connect

    University of Hawaii at Manoa; Sandia National Laboratories; Zhang, Fangtong; Kaiser, Ralf I.; Golan, Amir; Ahmed, Musahid; Hansen, Nils

    2012-02-22

    We studied the reaction of phenyl radicals (C6H5) with propylene (C3H6) exploiting a high temperature chemical reactor under combustion-like conditions (300 Torr, 1,200-1,500 K). The reaction products were probed in a supersonic beam by utilizing tunable vacuum ultraviolet (VUV) radiation from the Advanced Light Source and recording the photoionization efficiency (PIE) curves at mass-to-charge ratios of m/z = 118 (C9H10+) and m/z = 104 (C8H8+). Our results suggest that the methyl and atomic hydrogen losses are the two major reaction pathways with branching ratios of 86 10 percent and 14 10 percent. The isomer distributions were probed by fitting the recorded PIE curves with a linear combination of the PIE curves of the individual C9H10 and C8H8 isomers. Styrene (C6H5C2H3) was found to be the exclusive product contributing to m/z = 104 (C8H8+), whereas 3-phenylpropene, cis-1-phenylpropene, and 2-phenylpropene with branching ratios of 96 4 percent, 3 3 percent, and 1 1 percent could account for signal at m/z = 118 (C9H10+). Although searched for carefully, no evidence of the bicyclic indane molecule could be provided. The reaction mechanisms and branching ratios are explained in terms of electronic structure calculations nicely agreeing with a recent crossed molecular beam study on this system.

  17. Synthesis, structure of [H{sub 3} dien].(MF{sub 6}).H{sub 2}O (M=Cr, Fe) and {sup 57}Fe Moessbauer study of [H{sub 3} dien].(FeF{sub 6}).H{sub 2}O

    SciTech Connect

    Ben Ali, Amor Trang Dang, Minh; Greneche, Jean-Marc; Hemon-Ribaud, Annie; Leblanc, Marc; Maisonneuve, Vincent

    2007-06-15

    Single crystals of [H{sub 3} dien].(FeF{sub 6}).H{sub 2}O (I) and [H{sub 3} dien].(CrF{sub 6}).H{sub 2}O (II) are obtained by solvothermal synthesis under microwave heating. I is orthorhombic (Pna2{sub 1}) with a=11.530(2) A, b=6.6446(8) A, c=13.787(3) A, V=1056.3(2) A{sup 3} and Z=4. II is monoclinic (P2{sub 1} /c) with a=13.706(1) A, b=6.7606(6) A, c=11.3181(9) A, {beta}=99.38(1){sup o}, V=1034.7(1) A{sup 3} and Z=4. The structure determinations, performed from single crystal X-ray diffraction data, lead to the R {sub 1}/wR {sub 2} reliability factors 0.028/0.066 for I and 0.035/0.102 for II. The structures of I and II are built up from isolated FeF{sub 6} or CrF{sub 6} octahedra, water molecules and triprotonated amines. In both structures, each octahedron is connected by hydrogen bonds to six organic cations and two water molecules. The iron-based compound is also characterized by {sup 57}Fe Moessbauer spectrometry: the hyperfine structure confirms the presence of Fe{sup 3+} in octahedral coordination and reveals the existence of paramagnetic spin fluctuations. - Graphical abstract: Moessbauer spectra of [H{sub 3} dien].(FeF{sub 6}).H{sub 2}O.

  18. Thermal studies on the interaction behavior of ternary nitrate mixtures of UO2(NO3)2ṡ6H2O-NaNO3-Sr(NO3)2 at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Kalekar, Bhupesh; Raje, Naina; Reddy, A. V. R.

    2015-04-01

    Thermal and X-ray diffraction measurements have been used to study the formation of various nitrato-complexes as intermediates and mixed oxides as end products using different mol ratios of the ternary mixtures of UO2(NO3)2ṡ6H2O, NaNO3 and Sr(NO3)2 at high temperatures. These results indicate the interaction of UO2(NO3)2ṡ6H2O and NaNO3 in equimolar ratio to form sodium uranyl nitrate monohydrate (Na[UO2(NO3)3]ṡH2O), dimerized sodium uranyl oxynitrate (Na2[(UO2NO3)2(O)2]) and sodium diuranate (Na2U2O7). The decomposition temperature of Sr(NO3)2 decreased by 60 °C in the presence of in-situ formed Na2U2O7. The uranium of Na2U2O7 intermediate reacts with Sr(NO3)2 to form various strontium uranium mixed oxides depending on Sr to U ratio in the initial mixtures. During the interaction of Sr(NO3)2 with Na2U2O7, sodium separates out as amorphous Na2O in the mixtures, containing Sr to U ratio ⩾1. Na2O phase is not formed in the uranium rich ternary mixture.

  19. A combined electron paramagnetic resonance and fourier transform infrared study of the co(c(6)h(6))(1,2) complexes isolated in neat benzene or in cryogenic matrixes.

    PubMed

    Béchamp, Kevin; Levesque, Michelle; Joly, Helen; Manceron, Laurent

    2006-05-11

    The products obtained in the reaction of cobalt atoms in neat benzene or in a benzene/argon mixture at low temperature have been reinvestigated. At least three cobalt-containing species were detected by IR, namely, Co(C(6)H(6)), Co(C(6)H(6))(2), and Co(x)(C(6)H(6)), x>1. The IR bands were assigned to these complexes by monitoring their behavior as a function of (a) Co and C(6)H(6) concentration, (b) isotopic substitution, and (c) photoirradiation. We were able to analyze the sample in neat benzene by both electron paramagnetic resonance (EPR) and IR spectroscopy and to determine the magnetic parameters (g tensor and Co hyperfine interaction) for the Co(C(6)H(6))(2) sandwich compound. The large number of fundamental bands observed in the IR spectrum of Co(C(6)H(6))(2), the absorption pattern observed in the Co-ring stretching region of the IR spectrum of the mixed complex, Co(C(6)H(6))(C(6)D(6)) and the orthorhombic g-values extracted from the EPR spectrum are most consistent with nonequivalent benzene ligands in Co(C(6)H(6))(2), i.e., C(s) symmetry. A bonding scheme consistent with both the EPR and IR data for Co(C(6)H(6))(2) is discussed.

  20. DFT(B3LYP/LanL2DZ), non-linear optical and electrical studies of a new hybrid compound: [C6H10(NH3)2]CoCl4·H2O

    NASA Astrophysics Data System (ADS)

    Tounsi, Amal; Hamdi, Besma; Zouari, Ridha; Ben Salah, Abdelhamid

    2016-10-01

    A new organic-inorganic material [C6H10(NH3)2]CoCl4·H2O was reported. The title compound was synthesized at room temperature by slow evaporation and then characterized by a single X-ray diffraction, spectroscopic measurements, thermal analysis and dielectric technique. It crystallizes in the non-centrosymmetric space group Pna21 with the following unit cell parameters: a=12.5328(1) Å, b=9.0908(1) Å, c=11.7440(1) and α=β=γ=90°. The structure can be described by the alternation of two different cationic-anionic layers. It consists of isolated H2O, isolated [CoCl4]2- tetrahedral anions and diammoniumcyclohexane [C6H10(NH3)2]2+ cations, which are connected via N-H…Cl, N-H…O and O-H…N hydrogen bonds. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. Theoretical calculations were performed using DFT/B3LYP/LanL2DZ method for studying the molecular structure and vibrational spectra and especially to examine the non-linear optical behavior of the compound. Solid state 13C NMR spectrum shows three signals correspond to three different carbon environments. Thermal analysis discloses a phase transition at the temperature 315 K and the evaporation of water molecule at 327 K. A detailed dielectric study was reported and shows a good agreement with thermal measurements.

  1. Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3(NIT(C6H4OPh))]: A μ{sup +} spin relaxation study

    SciTech Connect

    Arosio, Paolo Orsini, Francesco; Corti, Maurizio; Mariani, Manuel; Bogani, Lapo; Caneschi, Andrea; Lago, Jorge; Lascialfari, Alessandro

    2015-05-07

    The spin dynamics of the molecular magnetic chain [Dy(hfac){sub 3}(NIT(C{sub 6}H{sub 4}OPh))] were investigated by means of the Muon Spin Relaxation (μ{sup +}SR) technique. This system consists of a magnetic lattice of alternating Dy(III) ions and radical spins, and exhibits single-chain-magnet behavior. The magnetic properties of [Dy(hfac){sub 3}(NIT(C{sub 6}H{sub 4}OPh))] have been studied by measuring the magnetization vs. temperature at different applied magnetic fields (H = 5, 3500, and 16500 Oe) and by performing μ{sup +}SR experiments vs. temperature in zero field and in a longitudinal applied magnetic field H = 3500 Oe. The muon asymmetry P(t) was fitted by the sum of three components, two stretched-exponential decays with fast and intermediate relaxation times, and a third slow exponential decay. The temperature dependence of the spin dynamics has been determined by analyzing the muon longitudinal relaxation rate λ{sub interm}(T), associated with the intermediate relaxing component. The experimental λ{sub interm}(T) data were fitted with a corrected phenomenological Bloembergen-Purcell-Pound law by using a distribution of thermally activated correlation times, which average to τ = τ{sub 0} exp(Δ/k{sub B}T), corresponding to a distribution of energy barriers Δ. The correlation times can be associated with the spin freezing that occurs when the system condenses in the ground state.

  2. VIBRATIONALLY EXCITED C{sub 6}H

    SciTech Connect

    Gottlieb, C. A.; McCarthy, M. C.; Thaddeus, P.

    2010-08-15

    Rotational spectra of the linear carbon chain radical C{sub 6}H in two low-lying excited vibrational states were observed both at millimeter wavelengths in a low-pressure glow discharge and at centimeter wavelengths in a supersonic molecular beam. Two series of harmonically related lines with rotational constants within 0.3% of the {sup 2{Pi}} ground state were assigned to the {sup 2{Sigma}} and {sup 2{Delta}} vibronic components of an excited bending vibrational level. Measurements of the intensities of the lines in the glow discharge indicate that the {sup 2{Sigma}} component lies very close to ground, but the {sup 2{Delta}} component is much higher in energy. The standard Hamiltonian for an isolated {sup 2{Delta}} state with five spectroscopic constants reproduces the observed rotational spectrum, but several high-order distortion terms in the spin-rotation interaction are needed to reproduce the spectrum of the {sup 2{Sigma}} component in C{sub 6}H and C{sub 6}D. The derived spectroscopic constants allow astronomers to calculate the rotational spectra of the {sup 2{Sigma}} and {sup 2{Delta}} states up to 260 GHz to within 0.1 km s{sup -1} or better in equivalent radial velocity.

  3. 77 FR 73452 - Grace Period Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-10

    ... Patent and Trademark Office Grace Period Study ACTION: Proposed collection; comment request. SUMMARY: The...Collection@uspto.gov . Include ``0651- 00xx Grace Period Study comment'' in the subject line of the message... are not fully understood. Few studies in the past ten years have dealt with the grace period, and...

  4. Synthesis, structure and optical studies of inorganic–organic hybrid semiconductor, (H{sub 3}NC{sub 6}H{sub 4}CH{sub 2}NH{sub 3}) PbI{sub 4}

    SciTech Connect

    Nageswara Rao, K.; Singh, Amit; Vijaya Prakash, G.

    2014-04-01

    Highlights: • New type of IO hybrid semiconductor has been synthesized and reported. • Inorganic (PbI{sub 4}){sup 2−} nano-ribbons are surrounded by organic entities. • Room-temperature optical exciton and charge-transfer features are reported. • Structural and optical mechanisms are useful in nanoscale electronic devices. - Abstract: Synthesis, structural and optical studies of inorganic–organic (IO) hybrid, 1,2-benzyldiammoniumtetraiodo plumbate (H{sub 3}NC{sub 6}H{sub 4}CH{sub 2}NH{sub 3}) PbI{sub 4} are presented. The titled compound crystallizes into triclinic system of P-1(2) space group with mutually surrounded inorganic (PbI{sub 4}){sup 2−} organic (C{sub 7}H{sub 12}N{sub 2}) entities. These one-dimensional IO hybrids are thermally stable up to 300 °C and show room-temperature exciton along with charge-transfer photoluminescence features. Structural and optical mechanisms are discussed for future applications in nanoscaled optoelectronic devices.

  5. α- to β-[C 6H 4(NH 3) 2] 2Bi 2I 10 reversible solid-state transition, thermochromic and optical studies in the p-phenylenediamine-based iodobismuthate(III) material

    NASA Astrophysics Data System (ADS)

    Hrizi, Chakib; Trigui, Ameni; Abid, Younes; Chniba-Boudjada, Nassira; Bordet, Pierre; Chaabouni, Slaheddine

    2011-12-01

    α-[C 6H 4(NH 3) 2] 2Bi 2I 10, which is a new material containing low-dimensional iodobismuthate anions, was synthesized and through its single crystal X-ray diffraction measurements, was proven to crystallize at room temperature in the centrosymmetric space group P2 1/c. It consists of a p-phenylenediammonium dication and a discrete (0-D) anion built up of edge-sharing bioctahedron. Due to the hydrogen bonds and the interatomic distances (Bi-I, I⋯I and π-π) changes, α-phase was transformed into the corresponding centrosymmetric β-phase, β-[C 6H 4(NH 3) 2] 2Bi 2I 10, through a single-crystal to single-crystal transformation occurring upon cooling to -28/-26 °C. Below the transition temperature, β-[C 6H 4(NH 3) 2] 2Bi 2I 10 crystallizes in the monoclinic system, centrosymmetric space group P2 1/n. Besides, the optical transmission measurements on α-[C 6H 4(NH 3) 2] 2Bi 2I 10 thin films have revealed two absorption bands at 2.47 and 3.01 eV. Finally, two room temperature photoluminescence emissions attributed to excitons radiative recombinations confined within the bioctahedra Bi 2I 104-, were observed in the red spectral range at 1.9 and 2.05 eV energy.

  6. Deep ultra violet and visible Raman spectroscopy studies of ion implanted 6H-SiC: Recrytallisation behaviour and thermal decomposition/thermal etching of the near surface region

    NASA Astrophysics Data System (ADS)

    Kuhudzai, R. J.; Malherbe, J. B.; van der Berg, N. G.; Hlatshwayo, T. T.; Odutemowo, O.; Prinsloo, L. C.; Buys, A. V.; Erasmus, R.; Wendler, E.

    2015-12-01

    The recystallisation behaviour and thermal decomposition of the near surface amorphised region of 6H-SiC have been investigated by Raman spectroscopy. 360 keV ions of iodine and silver were implanted at room temperature into wafers of 6H-SiC resulting in the amorphisation of the near surface region. Vacuum annealing of the samples was performed at 1200 °C for 5 h and then sequentially from 1200 to 1600 °C in steps of 100 °C for 30 h at each annealing temperature. Raman spectroscopy was performed using two laser wavelength excitation regimes, the 514 nm laser (visible region) and the 244 nm laser (deep ultraviolet region, DUV). Measurements in the visible region for samples annealed at 1200 °C for 5 h showed that the characteristic 6H-SiC peaks, namely, the Transverse Optical (TO) and Longitudinal Optical (LO) are similar to the virgin samples, albeit with lower intensity due to some retained defects upon recystallisation of the SiC surface region. The similarities between the virgin spectra and the annealed sample were due to the deep penetration of the 514 nm laser into 6H-SiC resulting in the signal from the bulk undamaged 6H-SiC contributing to the overall spectra. However, DUV laser excitation, which only probes the near surface region, shows that after annealing the peaks are broader and asymmetrical compared to the virgin samples. DUV Raman spectra of samples annealed at 1600 °C indicate that SiC has completely decomposed and the top surface layer is now covered by a carbon layer. However the deeper penetrating laser in the visible region showed that the extent of decomposition at 1600 °C was greater for the silver implanted samples than for the iodine implanted samples.

  7. Non-Periodic Helix TWT Study.

    DTIC Science & Technology

    1980-05-01

    IA-A087 413 LITTON SYSTEMS INC SAN CARLOS CA ELECTRON TUBE DIV F/6 9/1 NON-PERIODIC HELIX TWT STUDY.(U) MAY 80 N00173-76C-014 UNCLASSIFIED ML...IEEEEEEmhEEI U-80 - ’l////////,, 11111 128 25 L1. = *""L 1- 1.8 MICROCOPY RESOLUTION TEST CHART ’IT-, ( (NO-PERIODIC HELIX WTSTUDY0 I EXTENSION OF CONTRACT... Helix Circuit 4 - 2 Non-Periodic Helix Structure 7 3 Unwound Tape for Non-Periodic Helix 8 4 Typical Helix Assembly 10 5 Typical Ladder Assembly 11 6

  8. Periodization

    PubMed Central

    Lorenz, Daniel S.; Reiman, Michael P.; Walker, John C.

    2010-01-01

    Background: Clinicians are constantly faced with the challenge of designing training programs for injured and noninjured athletes that maximize healing and optimize performance. Periodization is a concept of systematic progression—that is, resistance training programs that follow predictable patterns of change in training variables. The strength training literature is abundant with studies comparing periodization schemes on uninjured, trained, and untrained athletes. The rehabilitation literature, however, is scarce with information about how to optimally design resistance training programs based on periodization principles for injured athletes. The purpose of this review is to discuss relevant training variables and methods of periodization, as well as periodization program outcomes. A secondary purpose is to provide an anecdotal framework regarding implementation of periodization principles into rehabilitation programs. Evidence Acquisition: A Medline search from 1979 to 2009 was implemented with the keywords periodization, strength training, rehabilitation, endurance, power, hypertrophy, and resistance training with the Boolean term AND in all possible combinations in the English language. Each author also undertook independent hand searching of article references used in this review. Results: Based on the studies researched, periodized strength training regimens demonstrate improved outcomes as compared to nonperiodized programs. Conclusions: Despite the evidence in the strength training literature supporting periodization programs, there is a considerable lack of data in the rehabilitation literature about program design and successful implementation of periodization into rehabilitation programs. PMID:23015982

  9. Evidence and detailed study of a second-order phase transition in the (C{sub 6}H{sub 11}NH{sub 3}){sub 2}[PbI{sub 4}] organic-inorganic hybrid material

    SciTech Connect

    Yangui, A.; Pillet, S.; Garrot, D.; Boukheddaden, K.; Triki, S.; Abid, Y.

    2015-03-21

    The thermal properties of the organic-inorganic hybrid material (C{sub 6}H{sub 11}NH{sub 3}){sub 2}[PbI{sub 4}] are investigated using diffuse reflectivity, spectroscopic ellipsometry, differential scanning calorimetry, Raman spectroscopy, and X-ray diffraction. The diffuse reflectivity, performed in heating mode, clearly evidences the presence of a singularity at 336 K. This is confirmed by the temperature dependence of the spectroscopic ellipsometry spectra, which points out a second-order phase transition at 336 K with a critical exponent ∼0.5. Differential scanning calorimetry measurements on a polycrystalline powder of (C{sub 6}H{sub 11}NH{sub 3}){sub 2}[PbI{sub 4}] show a reversible phase transition detected at T{sub C} = 336 K without hysteresis. Raman spectroscopy data suggest that this transition arises from a change in the interactions between inorganic sheets (([PbI{sub 4}]{sup 2−}){sub ∞}) and organic protonated molecules ([C{sub 6}H{sub 11}NH{sub 3}]{sup +}). The structural analysis from power X-ray diffraction reveals an incomplete order-disorder transition of the cyclohexylammonium cation, causing a subtle contraction of the inter-plane distance. The transition results from repulsive close contacts between the organic molecules in the interlayer spacing.

  10. Spectroscopic and dynamic NMR study, X-ray crystallography and DFT calculations of two phosphoramidates: (C4H3O2)P(O)(Cl)C6H14N and (C4H3O2)P(O)(C6H11NH)2

    NASA Astrophysics Data System (ADS)

    Oliveira, F. M.; Barbosa, L. C. A.; Demuner, A. J.; Maltha, C. R. A.; Fernandes, S. A.; Carneiro, J. W. de M.; Corrêa, R. S.; Doriguetto, A. C.

    2013-08-01

    In recent years, research in organophosphorus compounds, particularly phosphoramidates, has attracted attention because of their many applications. In this work, we report a combined experimental and theoretical study on the molecular structure and NMR spectra of two phosphoramidates (furan-2-yl N,N-diisopropylamidochlorophosphate (1) and furan-2-yl N,N,N',N'-dicyclohexylamidophosphate (2)). In the NMR time scale a free rotation of the Csbnd N/Psbnd N single bonds was observed at room temperature (298 K) while the rotation freezes below 195 K for compound 1. From dynamic NMR analysis, the activation free energy (ΔG#) for rotation of the Csbnd N/Psbnd N bonds was calculated as 9.9 ± 0.3 kcal mol-1. The experimental data were reinforced by theoretical calculation using the density functional theory method B3LYP and the 6-31G(d) basis set which provided activation energy (ΔE‡) of 9.2 kcal mol-1. The structures of compounds 1 and 2 were determined by single crystal X-ray diffraction method. Compound 1 is formed by a racemic mixture, whose presence was evidenced only in the structure determination by X-ray.

  11. Structural variation in ethylenediamine and -diphosphine adducts of (2,6-Me2C6H3S)2Pb: a single crystal X-ray diffraction and 207Pb solid-state NMR spectroscopy study.

    PubMed

    Rossini, Aaron J; Macgregor, Alan W; Smith, Anita S; Schatte, Gabriele; Schurko, Robert W; Briand, Glen G

    2013-07-14

    Coordination complexes of (2,6-Me2C6H3S)2Pb (1) with flexible bidentate ligands have been prepared to explore new bonding environments for Pb(II) thiolates. The reaction of 1 with a series of ethylenediamine and ethylenediphosphine ligands resulted in isolation of the adducts [(2,6-Me2C6H3S)2Pb]2(tmeda) (9), [(2,6-Me2C6H3S)2Pb]3(dmpe) (10) and [(2,6-Me2C6H3S)2Pb]2(dppe) (11) [tmeda = N,N,N',N'-tetramethylethylenediamine; dmpe = bis(dimethylphosphino)ethane; dppe = bis(diphenylphosphino)ethane]. The X-ray crystal structure of 9 shows a dinuclear species in which tmeda is chelating a ψ-trigonal bipyramidal S2N2 Pb centre via axial and equatorial sites. The structure of 10 displays a trinuclear structural unit in which dmpe is chelating a ψ-trigonal bipyramidal S2P2 Pb centre via equatorial sites. Compounds 9 and 10 also contain a second unique metal centre with ψ-tetrahedral S3Pb bonding motifs. The structure of 11 shows the dppe ligand bridging two Pb ψ-tetrahedral S2P metal bonding environments. Static (207)Pb solid-state NMR (SSNMR) spectra of 9-11 and [Ph4As][(PhS)3Pb] (12) were acquired with cross polarization (CP)-CPMG and frequency swept pulse (WURST)-CPMG pulse sequences, and the efficiencies of these pulse sequences are compared. The (207)Pb SSNMR spectra reveal that the lead chemical shift anisotropies (CSA) vary greatly between the different Pb sites, and are generally large in magnitude. DFT calculations are utilized to relate the orientations of the (207)Pb nuclear magnetic shielding tensors to the molecular structures, and to aid in spectral assignment where multiple Pb centres are present. The combination of X-ray diffraction, (207)Pb SSNMR and DFT is shown to be invaluable for the structural characterization of these important structural motifs, and should find wide-ranging application to numerous lead coordination compounds.

  12. Synthesis and study of fluorescence properties of novel pyrazolo[4‧,3‧:5,6]pyrido[2,3-d]pyrimidin-5(6H)-one derivatives

    NASA Astrophysics Data System (ADS)

    Quiroga, Jairo; Acosta, Paola; Ortiz, Alejandro; Insuasty, Braulio; Abonia, Rodrigo

    2015-10-01

    New pyrazolo[4‧,3‧:5,6]pyrido[2,3-d]pyrimidin-5(6H)-one derivatives 5 were prepared by cyclocondensation reaction between heterocyclic o-aminonitriles 3 and carboxylic acids 4 in the presence of sulfuric acid as catalyst. This procedure provides the desired compound in good yield with a simple one-step methodology. The obtained products show interesting fluorescence properties in both solution and solid state; in this way several spectra of absorption and emission were measured for selected compounds 5b, 5e, 5g and 5j, showing a broad and intense emission band around of 470 nm. In other to understand the electronic transition processes, theoretical calculations were performed at TD-DFT level, using B3LYP as functional and 6-31(d,p) as basis set, finding a good agreement with experimental measurements.

  13. Static and dynamic interaction between π and d electrons in organic superconductor β″-(BEDT-TTF)4[(H3O ) Fe (C2O4)3] .C6H5Br studied by 13C NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Ihara, Y.; Futami, Y.; Kawamoto, A.; Matsui, K.; Goto, T.; Sasaki, T.; Benmansour, S.; Gómez-García, C. J.

    2016-08-01

    We present the results of 13C NMR experiments in an organic superconductor with localized Fe spins β″-(BEDT-TTF) 4[(H3O ) Fe (C2O4)3] .C6H5Br . We reveal the antiferromagnetic coupling between Fe d spins and π spins, which creates an exchange field antiparallel to the external field direction at the π electrons. In addition to the static effects of Fe spins, we show from the nuclear spin-lattice relaxation rate measurement that the magnetic fluctuations generated by Fe spins are suppressed at low temperatures and high magnetic fields. These conditions are suitable to stabilize the field-induced superconductivity by the field compensation mechanism. After the suppression of Fe-spin dynamics by a magnetic field of 19 T, we observed the underlying π -electron contribution. We discuss a possible anomaly in the π -electron system.

  14. Mn(CO)[sub 5]C(O)-p-C[sub 6]H[sub 5]CH[sub 3]-catalyzed hydrosilane SiH/SiD exchange. Evidence from a kinetics study implicating coordinatively unsaturated manganese silyl intermediates

    SciTech Connect

    Gregg, B.T.; Cutler, A.R. )

    1993-06-01

    The manganese p-toluoyl complex Mn(CO)[sub 5]C(O)-p-CH[sub 3]C[sub 6]H[sub 4] catalyzes SiH/SiD exchange between DSiMe[sub 2]Ph and HSiMe[sub 2]Et at room temperature in C[sub 6]D[sub 6]. The preequilibrium kinetics are consistent with a second-order isotope exchange reaction; plots of initial velocities [nu] against [HSiMe[sub 2]Et] further established saturation kinetics. Lineweaver-Burk plots are in accord with a ping-pong bi-bi mechanism that operates under rapid equilibrium conditions and involves coordinatively unsaturated manganese silyls, (CO)[sub 4]MnSiMe[sub 2/R], as active catalysts. 29 refs., 2 figs.

  15. A vibrational spectroscopic study of the silicate mineral harmotome--(Ba,Na,K)1-2(Si,Al)8O16⋅6H2O--a natural zeolite.

    PubMed

    Frost, Ray L; López, Andrés; Wang, Lina; Romano, Antônio Wilson; Scholz, Ricardo

    2015-02-25

    The mineral harmotome (Ba,Na,K)1-2(Si,Al)8O16⋅6H2O is a crystalline sodium calcium silicate which has the potential to be used in plaster boards and other industrial applications. It is a natural zeolite with catalytic potential. Raman bands at 1020 and 1102 cm(-1) are assigned to the SiO stretching vibrations of three dimensional siloxane units. Raman bands at 428, 470 and 491 cm(-1) are assigned to OSiO bending modes. The broad Raman bands at around 699, 728, 768 cm(-1) are attributed to water librational modes. Intense Raman bands in the 3100 to 3800 cm(-1) spectral range are assigned to OH stretching vibrations of water in harmotome. Infrared spectra are in harmony with the Raman spectra. A sharp infrared band at 3731 cm(-1) is assigned to the OH stretching vibration of SiOH units. Raman spectroscopy with complimentary infrared spectroscopy enables the characterization of the silicate mineral harmotome.

  16. A vibrational spectroscopic study of the silicate mineral harmotome - (Ba,Na,K)1-2(Si,Al)8O16ṡ6H2O - A natural zeolite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Wang, Lina; Romano, Antônio Wilson; Scholz, Ricardo

    2015-02-01

    The mineral harmotome (Ba,Na,K)1-2(Si,Al)8O16ṡ6H2O is a crystalline sodium calcium silicate which has the potential to be used in plaster boards and other industrial applications. It is a natural zeolite with catalytic potential. Raman bands at 1020 and 1102 cm-1 are assigned to the SiO stretching vibrations of three dimensional siloxane units. Raman bands at 428, 470 and 491 cm-1 are assigned to OSiO bending modes. The broad Raman bands at around 699, 728, 768 cm-1 are attributed to water librational modes. Intense Raman bands in the 3100 to 3800 cm-1 spectral range are assigned to OH stretching vibrations of water in harmotome. Infrared spectra are in harmony with the Raman spectra. A sharp infrared band at 3731 cm-1 is assigned to the OH stretching vibration of SiOH units. Raman spectroscopy with complimentary infrared spectroscopy enables the characterization of the silicate mineral harmotome.

  17. Synthesis of opioidmimetics, 3-[H-Dmt-NH(CH(2))(m)]-6-[H-Dmt-NH(CH(2))(n)]-2(1H)-pyrazinones, and studies on structure-activity relationships.

    PubMed

    Shiotani, Kimitaka; Miyazaki, Anna; Li, Tingyou; Tsuda, Yuko; Yokoi, Toshio; Ambo, Akihiro; Sasaki, Yusuke; Bryant, Sharon D; Jinsmaa, Yunden; Lazarus, Lawrence H; Okada, Yoshio

    2007-11-01

    Opioidmimetics containing 3-[H-Dmt-NH-(CH(2))(m)]-6-[H-Dmt-NH-(CH(2))(n)]-2(1H)-pyrazinone symmetric (m = n, 1-4) (1 - 4) and asymmetric (m, n = 1 - 4) aliphatic chains (5 - 16) were synthesized using dipeptidyl chloromethylketone intermediates. They had high mu-affinity (K(i)mu = 0.021 - 2.94 nM), delta-affinity (K(i)delta = 1.06 - 152.6 nM), and mu selectivity (K(i)delta/K(i)mu = 14 - 3,126). The opioidmimetics (1 - 16) exhibited mu agonism in proportion to their mu-receptor affinity. delta-Agonism was essentially lacking in the compounds except (4) and (16), and (1) and (2) indicated weak delta antagonism (pA(2) = 6.47 and 6.56, respectively). The data verify that a specific length of aliphatic linker is required between the Dmt pharmacophore and the pyrazinone ring to produce unique mu-opioid receptor ligands.

  18. Ab initio/GIAO-CCSD(T) (13)C NMR study of the rearrangement and dynamic aspects of rapidly equilibrating tertiary carbocations, C6H13(+) and C7H15(+).

    PubMed

    Olah, George A; Prakash, G K Surya; Rasul, Golam

    2016-01-05

    The rearrangement pathways of the equilibrating tertiary carbocations, 2,3-dimethyl-2-butyl cation (C6H13(+), 1), 2,3,3-trimethyl-2-butyl cation (C7H15(+), 5) and 2,3-dimethyl-2-pentyl cation (C7H15(+), 8 and 9) were investigated using the ab initio/GIAO-CCSD(T) (13)C NMR method. Comparing the calculated and experimental (13)C NMR chemical shifts of a series of carbocations indicates that excellent prediction of δ(13)C could be achieved through scaling. In the case of symmetrical equilibrating cations (1 and 5) the Wagner-Meerwein 1,2-hydride and 1,2-methide shifts, respectively, produce the same structure. This indicates that the overall (13)C NMR chemical shifts are conserved and independent of temperature. However, in the case of unsymmetrical equilibrating cations (8 and 9) the Wagner-Meerwein shift produces different tertiary structures, which have slightly different thermodynamic stabilities and, thus, different spectra. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level structure 8 is only 90 calories/mol more stable than structure 9. Based on computed (13)C NMR chemical shift calculations, mole fractions of these isomers were determined by assuming the observed chemical shifts are due to the weighted average of the chemical shifts of the static ions.

  19. Study on the interaction of 6-(2-morpholin-4-yl-ethyl)-6H-indolo [2,3-b]quinoxaline hydrochloride with human serum albumin by fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Yegorova, A.; Leonenko, I.; Scrypynets, Yu; Maltsev, G.; Antonovich, V.

    2016-09-01

    Under physiological conditions, in vitro interaction between the bio-active substance 6-(2-morpholin-4-yl-ethyl)-6H-indolo[2,3-b]quinoxaline hydrochloride (MIQ) and human serum albumin (HSA) was investigated at an excitation wavelength 260 nm and at different temperatures (298 K, 308 K and 313 K) by fluorescence emission spectroscopy. From spectral analysis, MIQ showed a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constant is estimated asK A   =  2.55  ×  10-4 l · mol-1 at 298 K. Based on the thermodynamic parameters evaluated from the van ’t Hoff equation, the enthalpy change (ΔH°) and entropy change (ΔS°) were derived to be negative values. A value of 2.37 nm for the average distance r between MIQ (acceptor) and tryptophan residues of HSA (donor) was derived from the fluorescence resonance energy transfer. UV/vis absorption spectra were used to confirm the quenching mechanism.

  20. Dual Emission of a Novel (P,N) Re(I) Complex: A Computational and Experimental Study on [P,N-{(C6H5)2(C5H4N)P}Re(CO)3Br].

    PubMed

    Pizarro, Nancy; Duque, Mario; Chamorro, Eduardo; Nonell, Santi; Manzur, Jorge; de la Fuente, Julio R; Günther, Germán; Cepeda-Plaza, Marjorie; Vega, Andrés

    2015-04-30

    The spectroscopic, electrochemical, and photophysical properties of the new complex [P,N-{(C6H5)2(C5H4N)P}Re(CO)3Br] are reported. The UV-vis spectrum in dichloromethane shows an absorption maximum centered at 315 nm and a shoulder at 350 nm. These absorption bands have been characterized to have MLCT character. Excitation at both wavelengths (maximum and shoulder) leads to an emission band centered at 550 nm. Cyclic voltammetry experiments show two ill-defined irreversible oxidation waves around +1.50 and 1.80 V that are assigned to Re(I)/Re(II) and Re(II)/Re(III) couples whereas an irreversible reduction signal centered at -1.80 V is likewise assigned to a ligand reduction process. These results support the proposal of the MLCT nature of the states implied by the emission of the complex. The luminescent decay fits to a biexponential function, where the lifetimes and emission quantum yields are dependent on the solvent polarity. DFT calculations suggest that dπ → π*pyridine and dπ → π*phenyl excited states may account for the existence of two decay lifetimes.

  1. MR LLRF VXI upgrade beam study period

    SciTech Connect

    Mesiner, K.; /Fermilab

    1995-01-01

    AD/RFI/LLRF group personnel performed several studies with the MR LLRF VXI upgrade system during the evening of 7/29/95. The study period lasted about 4 hours. The MR operating conditions were a mixture of $29 and $2B cycles, with beam injected only on the $29. The author believes the $2B cycles were present for reasons unrelated to the study. The basic study period goal was to test the initial VXI version of MR LLRF finite state machine (FSM) execution. This goal represents what has been called MR LLRF VXI Upgrade Implementation Stage No.2 throughout presentations and documentation on the upgrade project. The test includes control of MR LLRF NIM hardware, the MR RF cavities, and beam via XVI TTL FSM outputs. Numerous MR LLRF VXI system objects, or components, must work together correctly for a successful test. Very briefly, the required objects include VXI Front End hardware, the ACNET/Front End interface code, and the VXI/NIM Interface chassis (the chassis solves VXI-CAMAC-NIM RF and FSM output connectivity and development problems). Though this initial FSM does not yet fully support Upgrade Implementation Stage 2 functionality, all code and hardware for the following basic functionality is tested.

  2. Rhenium Complex with Noninnocent Dioxolene Ligand: Combined Experimental and ab Initio Study of [(3,5-di-tert-Bu2C6H2O2)ReCl3(OPPh3)].

    PubMed

    Abramov, Pavel A; Gritsan, Nina P; Suturina, Elizaveta A; Bogomyakov, Artem S; Sokolov, Maxim N

    2015-07-20

    Reaction of [ReOCl3(PPh3)2] with 3,5-di-tert-butyl-1,2-benzoquinone (3,5-DTBQ) in hot toluene produces a new complex [(3,5-di-tert-Bu2C6H2O2)Re(OPPh3)Cl3] (1), which was isolated and characterized by elemental analysis, IR, UV-vis spectroscopy, and cyclic voltammetry. In order to clarify the charge state of rhenium and the coordinated dioxolene ligand, X-ray experiments at 150 and 290 K were carried out. The C-O, C-C, and Re-O bond distances at both 150 and 290 K fall between those for semiquinolate (3,5-DTBSQ) and catecholate (3,5-DTBCat) forms; an empirical "metrical oxidation state" of the dioxolene ligand was estimated to be -1.5. High-level ab initio calculations (SOC-CASSCF/NEVPT2) revealed a mixed valence nature of the triplet ground state of complex 1 corresponding to a superposition of the Re(IV)-SQ and Re(V)-cat forms. In agreement with the high-level ab initio and DFT calculations, the temperature dependence of the magnetic susceptibility (5-300 K) is well described in the assumption of the triplet ground state, with the anomalously large zero-field splitting (ZFS) arising from the spin-orbit coupling. According to the ab initio calculations, all absorption bands in the visible region of the electronic absorptions spectrum are assigned to the LMCT bands, with significant contribution of the intraligand transition in the most intense band at 555 nm.

  3. Topological study of the periodic system.

    PubMed

    Restrepo, Guillermo; Mesa, Héber; Llanos, Eugenio J; Villaveces, José L

    2004-01-01

    We carried out a topological study of the Space of Chemical Elements, SCE, based on a clustering analysis of 72 elements, each one defined by a vector of 31 properties. We looked for neighborhoods, boundaries, and other topological properties of the SCE. Among the results one sees the well-known patterns of the Periodic Table and relationships such as the Singularity Principle and the Diagonal Relationship, but there appears also a robustness property of some of the better-known families of elements. Alkaline metals and Noble Gases are sets whose neighborhoods have no other elements besides themselves, whereas the topological boundary of the set of metals is formed by semimetallic elements.

  4. {sup 203,205}Tl NMR Studies of Crystallographically Characterized Thallium Alkoxides. X-Ray Structures of [Tl(OCH{sub 2}CH{sub 3})]4 and [Tl(OAr)]{sub infinity} where OAr = OC{sub 6}H{sub 3}(Me){sub 2}-2,6 and OC{sub 6}H{sub 3}(Pr{sup i}){sub 2}-2,6

    SciTech Connect

    ZECHMANN,CECILIA A.; BOYLE,TIMOTHY J.; PEDROTTY,DAWN M.; ALAM,TODD M.; LANG,DAVID P.; SCOTT,BRIAN L.

    2000-07-25

    [Tl(OCH{sub 2}CH{sub 3})]{sub 4}, (1) was reacted with excess HOR to prepare a series of [Tl(OR)]{sub n} where OR= OCHMe{sub 2} (2, n = 4), OCMe{sub 3} (3, n = 4), OCH{sub 2}CMe{sub 3} (4, n = 4), OC{sub 6}H{sub 3}(Me){sub 2}-2,6 (5, n = {infinity}), and OC{sub 6}H{sub 3}(Pr{sup i}){sub 2}-2,6 (6, n = {infinity}). Single crystal X-ray diffraction was used to determine the structure of compounds ligated by more sterically demanding ligands. Compound 4 was found to adopt a cubane structure, while 5 and 6 formed linear polymeric structures. These compounds were additionally characterized by {sup 203,205}Tl solution and {sup 205}Tl solid state NMR. Compounds 1--4 were found to remain intact in solution while the polymeric species, 5 and 6, appeared to be fluxional. While variations in the solution and solid state structures for the tetrameric [Tl(OR)]{sub 4} and polymeric [Tl(OAr)]{sub {infinity}} may be influenced by the steric hindrance of their respective ligands, the covalency of the species is believed to be more an effect of the parent alcohol acidity.

  5. [The Hydrothermal Synthesis, Structure and Spectroscopy Study on (H2dap)6H[V12B16O54(OH)4] · 12H2O (dap = 1, 2-diaminopropane)].

    PubMed

    Guo, Zhen-qiang; Chen, Yi-ping; Huang, Meng-meng; Zhou, Meng-qian; Sun, Yan-qiong

    2015-09-01

    A polyoxovanadium borate (H2 dap)6H[V12B16O54(OH)4] · 12H2O (dap=1,2-diaminopropane) with novel structure was hydrothermally synthesized and characterized by the single crystal X-ray diffraction. It crystallizes in triclinic system with space group Piand unit cell parameters a=19.027(4), b=16.142(3) Å, c=26.679(5) Å, α=90°, β=101.06(3)°, γ=90°, V=8042(3) Å3, Z=4, Dc=1.962 g · cm(-3), μ=1.456 mm(-1), F(000)=4776, the final R1=0.0626, wR2=0.1927, S=1.003,for 7635 observed reflections with I>2σ(I). It is showed that the compound 1 is composed of V12B16 clusters unit and dap which is as a counter ion, and a two-dimensional layered structure is obtained by the effect of hydrogen bonding between the cluster units and dap, and between the layers via strong hydrogen bonds to form a three-dimensional supramolecular structure. The compound 1 were also characterized by IR, two-dimensional infrared (2D IR) correlation spectroscopy with magnetic and thermal perturbation, UV/Vis DRS spectra. The relationship between the structure and spectroscopy properties was discussed. The IR spectrum showed that the antisymmetric stretching vibration absorption peak νas (V-Oμ) and symmetric stretching vibration absorption peaks νs (V-Oμ) appeared at 775 and 683 cm(-1) respectively, whereas the vibration absorption peak in ν(B-O) of BO3 and the vibration absorption peak in ν(B-O) of BO4 appeared at 1350 and 1050 cm(-1) respectively. The response of the stretching vibrations of B-O and V-O was detected in the 2D IR correlation spectra with magentic perturbation. In addition, the response of the stretching vibrations of B-OH, B-O and V-O-V was detected in the 2D IR correlation spectra with thermal perturbation.

  6. Global reaction route mapping of isomerization pathways of exotic C{sub 6}H molecular species

    SciTech Connect

    Vikas, E-mail: qlabspu@yahoo.com; Kaur, Gurpreet

    2013-12-14

    C{sub 6}H radical is known to exist in the astrophysical environment in linear form; however, it may originate from nonlinear isomeric forms. Potential energy surface of C{sub 6}H is explored to search isomers of C{sub 6}H and transition states connecting them. This work reports first-ever identification of reaction pathways for isomerization of C{sub 6}H. The reaction route search is performed through global reaction route mapping method, which utilizes an uphill walking technique based on an anharmonic downward distortion following approach to search intermediates and transition states. The computations performed at the CASSCF/aug-cc-pVTZ, CCSD(T)/6-311++G(d,p)//DFT/B3LYP/6-311++G(d,p), and DFT/B3LYP/aug-cc-pVTZ levels of the theory identified 14 isomers (including 8 new isomeric forms of C{sub 6}H) and 28 transition states. Most of the identified isomers are found to have significant multireference character. The kinetic stability and natural bond orbital analysis of the identified isomers is also investigated. The isomeric forms are further characterized using spectral analysis involving rotational constants, vibrational frequencies, and Raman scattering activities as well as analyzing the effect of isotopic substitution of hydrogen on the spectral features. This study proposes that the linear-C{sub 6}H can readily isomerize to a six-member ring isomer.

  7. Global reaction route mapping of isomerization pathways of exotic C6H molecular species

    NASA Astrophysics Data System (ADS)

    Vikas, Kaur, Gurpreet

    2013-12-01

    C6H radical is known to exist in the astrophysical environment in linear form; however, it may originate from nonlinear isomeric forms. Potential energy surface of C6H is explored to search isomers of C6H and transition states connecting them. This work reports first-ever identification of reaction pathways for isomerization of C6H. The reaction route search is performed through global reaction route mapping method, which utilizes an uphill walking technique based on an anharmonic downward distortion following approach to search intermediates and transition states. The computations performed at the CASSCF/aug-cc-pVTZ, CCSD(T)/6-311++G(d,p)//DFT/B3LYP/6-311++G(d,p), and DFT/B3LYP/aug-cc-pVTZ levels of the theory identified 14 isomers (including 8 new isomeric forms of C6H) and 28 transition states. Most of the identified isomers are found to have significant multireference character. The kinetic stability and natural bond orbital analysis of the identified isomers is also investigated. The isomeric forms are further characterized using spectral analysis involving rotational constants, vibrational frequencies, and Raman scattering activities as well as analyzing the effect of isotopic substitution of hydrogen on the spectral features. This study proposes that the linear-C6H can readily isomerize to a six-member ring isomer.

  8. Studying the Nazi Period: Some Considerations.

    ERIC Educational Resources Information Center

    Molnar, Alex; And Others

    1984-01-01

    Students should be taught how to make well-reasoned and analytic judgments about the Nazis. The process of arriving at judgments about the Nazi period should be characterized by a factual knowledge of the Nazi era within a general historical knowledge of the period, sympathy, and an open mind. (RM)

  9. Growth of high quality 6H-SiC epitaxial films on vicinal (0001) 6H-SiC wafers

    NASA Technical Reports Server (NTRS)

    Powell, J. A.; Larkin, D. J.; Matus, L. G.; Choyke, W. J.; Bradshaw, J. L.

    1990-01-01

    Previously reported growth of SiC films on SiC by chemical vapor deposition (CVD) used alpha-SiC crystal substrates. The CVD growth and evaluation of high quality 6H-SiC films on 6H-SiC wafers cut from large boules grown by the modified-sublimation process is reported. The single-crystal 6H-SiC films were grown on wafers oriented 3 to 4 deg off the (0001) plane toward the 11-20 direction. The films, up to 12 microns thick, had surfaces that were smooth and featureless. The high quality of the films was demonstrated by optical and electron microscopy, and low-temperature photoluminescence.

  10. Luminescence mechanisms in 6H-SiC nanocrystals

    NASA Astrophysics Data System (ADS)

    Botsoa, J.; Bluet, J. M.; Lysenko, V.; Sfaxi, L.; Zakharko, Y.; Marty, O.; Guillot, G.

    2009-10-01

    Experimental conditions allowing consequent selection of a dominating photoluminescence mechanism in 6H-SiC nanocrystals at room temperature are reported. Electrostatic screening of surface states involved in radiative transitions can be efficiently achieved by polar ethanol molecules. This leads to a preponderant radiative channel between the electronic levels corresponding to the impurity atoms (N and Al). This radiative channel is deactivated by centrifugation-induced selection of the smallest colloidal 6H-SiC nanocrystals in which the probability to have both donor and acceptor atoms is negligible. Consequently, for these smallest 6H-SiC nanocrystals with switched off transitions between surface states and impurity levels, quantum-confinement effect can be clearly observed. The formation of energy subbands in the 6H-SiC nanocrystals is then evidenced from photoluminescence excitation and absorption measurements performed on the centrifuged colloidal nanosuspension. A most probable mean diameter of 1.9 nm for these particles is deduced from calculation of energy levels in the effective-mass approximation.

  11. Characterization of a New Organic-Cation Cyclotetraphosphate: (1,4-HOC 6H 4NH 3) 4P 4O 12· 6H 2O

    NASA Astrophysics Data System (ADS)

    Soumhi, E. H.; Saadoune, I.; Driss, A.; Jouini, T.

    1999-05-01

    The tetra(para-phenolammonium)cyclotetraphosphate hexahydrate, (1,4-HOC6H4NH3)4P4O12· 6H2O (M=864.51 g mol-1), is monoclinicP21/cwith the unit cell parametersa=9.836(2) Å,b=8.591(1) Å,c:22.769(5) Å,β=95.41(2)°. The structure of this compound can be described as a succession of inorganic and organic sheets parallel to the (001) plane. The existence of the OH and NH3groups in positionparato the organic cation leads to the cohesion of the inorganic sheets, forming a three-dimensional network.The IR spectrum of (1,4-HOC6H4NH3)4P4O12· 6H2O is reported and discussed according to the theoretical group analysis. The IR data confirm the atomic arrangement within the structure. The coupled TG-DTA thermal study shows the successive departure of four and two water molecules, confirming the hydrated character of this cyclophosphate.

  12. Identification and analysis of the human murine putative chromatin structure regulator SUPT6H and Supt6h

    SciTech Connect

    Chiang, Pei-Wen; Wang, SuQing; Hillman, J.

    1996-06-15

    We have isolated and sequenced SUPT6H and Supt6h, the human and murine homologues of the Saccharomyces cerevisiae and Caenorhabditis elegans genes SPT6 (P using 1603 aa = 6.7 e-{sup 95}) and emb-5 (P using 1603 aa = 7.0 e-{sup 288}), respectively. The human and murine SPT6 homologues are virtually identical, as they share >98% identity and >99% similarity at the protein level. The derived amino acid sequences of these two genes predict a 1603-aa protein (human) and a 1726-bp protein (mouse), respectively. There were several known features, including a highly acidic 5{prime}-region, a degenerate SH2 domain, and a leucine zipper. These features are consistent with a nuclear protein that regulates transcription, whose extreme conservation underscores the likely importance of this gene in mammalian development. Expression of human and murine SPT6 homologues was analyzed by Northern blotting, which revealed a 7.0-kb transcript that was expressed constitutively. The SPT6 homologue was mapped to chromosome 17q11.2 in human by somatic cell hybrid analysis and in situ hybridization. These data indicate that SUPT6H and Supt6h are functionally analogous to SPT6 and emb-5 and may therefore regulate transcription through establishment or maintenance of chromatin structure. 23 refs., 3 figs.

  13. Interplay between tetrel and triel bonds in RC6H4CN⋯MF3CN⋯BX3 complexes: A combined symmetry-adapted perturbation theory, Møller-Plesset, and quantum theory of atoms-in-molecules study.

    PubMed

    Yourdkhani, Sirous; Korona, Tatiana; Hadipour, Nasser L

    2015-12-15

    Intermolecular ternary complexes composed of: (1) the centrally placed trifluoroacetonitrile or its higher analogs with central carbon exchanged by silicon or germanium (M = C, Si, Ge), (2) the benzonitrile molecule or its para derivatives on one side, and (3) the boron trifluoride of trichloride molecule (X = F, Cl) on the opposite side as well as the corresponding intermolecular tetrel- and triel-bonded binary complexes, were investigated by symmetry-adapted perturbation theory (SAPT) and the supermolecular Møller-Plesset method (MP2) at the complete basis set limit for optimized geometries. A character of interactions was studied by quantum theory of atoms-in-molecules (QTAIM). A comparison of interaction energies and QTAIM bond descriptors for dimers and trimers reveals that tetrel and triel bonds increase in their strength if present together in the trimer. For the triel-bonded complex, this growth leads to a change of the bond character from closed-shell to partly covalent for Si or Ge tetrel atoms, so the resulting bonding scheme corresponds to a preliminary stage of the SN2 reaction. Limitations of the Lewis theory of acids and bases were shown by its failure in predicting the stability order of the triel complexes. The necessity of including interaction energy terms beyond the electrostatic component for an elucidation of the nature of σ- and π-holes was presented by a SAPT energy decomposition and by a study of differences in monomer electrostatic potentials obtained either from isolated monomer densities, or from densities resulting from a perturbation with the effective field of another monomer.

  14. Kinetic and theoretical studies on the protonation of [Ni(2-SC6H4N){PhP(CH2CH2PPh2)2}]+: nitrogen versus sulfur as the protonation site.

    PubMed

    Petrou, Athinoula L; Koutselos, Andreas D; Wahab, Hilal S; Clegg, William; Harrington, Ross W; Henderson, Richard A

    2011-02-07

    The complexes [Ni(4-Spy)(triphos)]BPh(4) and [Ni(2-Spy)(triphos)]BPh(4) {triphos = PhP(CH(2)CH(2)PPh(2))(2), 4-Spy = 4-pyridinethiolate, 2-Spy = 2-pyridinethiolate} have been prepared and characterized both spectroscopically and using X-ray crystallography. In both complexes the triphos is a tridentate ligand. However, [Ni(4-Spy)(triphos)](+) comprises a 4-coordinate, square-planar nickel with the 4-Spy ligand bound to the nickel through the sulfur while [Ni(2-Spy)(triphos)](+) contains a 5-coordinate, trigonal-bipyramidal nickel with a bidentate 2-Spy ligand bound to the nickel through both sulfur and nitrogen. The kinetics of the reactions of [Ni(4-Spy)(triphos)](+) and [Ni(2-Spy)(triphos)](+) with lutH(+) (lut = 2,6-dimethylpyridine) in MeCN have been studied using stopped-flow spectrophotometry, and the two complexes show very different reactivities. The reaction of [Ni(4-Spy)(triphos)](+) with lutH(+) is complete within the deadtime of the stopped-flow apparatus (2 ms) and corresponds to protonation of the nitrogen. However, upon mixing [Ni(2-Spy)(triphos)](+) and lutH(+) a reaction is observed (on the seconds time scale) to produce an equilibrium mixture. The mechanistic interpretation of the rate law has been aided by the application of MSINDO semiempirical and ADF calculations. The kinetics and calculations are consistent with the reaction between [Ni(2-Spy)(triphos)](+) and lutH(+) involving initial protonation of the sulfur followed by dissociation of the nitrogen and subsequent transfer of the proton from sulfur to nitrogen. The factors affecting the position of protonation and the coupling of the coordination state of the 2-pyridinethiolate ligand to the site of protonation are discussed.

  15. 6H Silicon Carbide Photoconductive Switches for High Power Applications

    DTIC Science & Technology

    2006-11-01

    6H SILICON CARBIDE PHOTOCONDUCTIVE SWITCHES FOR HIGH POWER APPLICATIONS W. C. Nunnally*, N. Islam, K. Kelkar & C. Fessler Photonics for Radars...PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Photonics for Radars and Optical Systems...switches. Additional work by the UMC Photonics for Radar and Optical Systems (PROS) group has demonstrated that the relatively new material of

  16. Infrared spectroscopic study of SO42- ions included in M‧2M‧‧(SeO4)2ṡ6H2O (Me‧ = K, NH4+; M‧‧ = Mg, Co, Ni, Cu, Zn) and NH4+ ions included in K2M(XO4)2ṡ6H2O (X = S, Se; M‧‧ = Mg, Co, Ni, Cu, Zn)

    NASA Astrophysics Data System (ADS)

    Marinova, D.; Karadjova, V.; Stoilova, D.

    2015-01-01

    Infrared spectra of Tutton compounds, M‧2M‧‧(XO4)2ṡ6H2O (M‧ = K, NH4+; M‧‧ = Mg, Co, Ni, Cu, Zn; X = S, Se), as well as those of SO42- guest ions included in selenate host lattices and of NH4+ guest ions included in potassium host lattices are presented and discussed in the regions of ν3 and ν1 of SO42- guest ions, ν4 of NH4+ guest ions and water librations. The SO42- guest ions matrix-isolated in selenate matrices (approximately 2 mol%) exhibit three bands corresponding to ν3 and one band corresponding to ν1 in good agreement with the low site symmetry C1 of the host selenate ions. When the larger SeO42- ions are replaced by the smaller SO42- ions the mean values of the asymmetric stretching modes νbar3 of the included SO42- ions are slightly shifted to lower frequencies as compared to those of the same ions in the neat sulfate compounds due to the smaller repulsion potential of the selenate matrices (larger unit-cell volumes of the selenates). It has been established that the extent of energetic distortion of the sulfate ions matrix-isolated in the ammonium selenates as deduced from the values of Δν3 and Δν3/νc is stronger than that of the same ions matrix-isolated in the potassium selenates due to the formation of hydrogen bonds between the SO42- guest ions with both the water molecules in the host compounds and the NH4+ host ions (for example, Δν3 of the sulfate guest ions have values of 30 and 51 cm-1 in the nickel potassium and ammonium compounds, and 33 and 49 cm-1 in the zinc potassium and ammonium compounds, respectively). The infrared spectra of ammonium doped potassium sulfate matrices show three bands corresponding to Δν4 of the included ammonium ions in agreement with the low site symmetry C1 of the host potassium ions. However, the inclusion of ammonium ions in selenate matrices (with exception of the magnesium compound) leads to the appearance of four bands in the region of ν4. At that stage of our knowledge we assume

  17. Studies of Long Period Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Ratajczak, M.; Hełminiak, K. G.; Konacki, M.

    2015-07-01

    The survey of long period eclipsing binaries from the All Sky Automated Survey (ASAS) catalog aims at searching for and characterizing subgiants and red giants in double-lined detached binary systems. Absolute physical and orbital parameters are presented based on radial velocities from high-quality optical spectra obtained with the following telescope/instrument combinations: 8.2 m Subaru/HDS, ESO 3.6 m/HARPS, 1.9 m Radcliffe/GIRAFFE, CTIO 1.5 m/CHIRON, and 1.2 m Euler/CORALIE. Photometric data from ASAS, SuperWASP, and the Solaris Project were also used. We discuss the derived uncertainties for the individual masses and radii of the components (better than 3% for several systems), as well as results from the spectral analysis performed for components of systems whose spectra we disentangled.

  18. Interface-structure of the Si/SiC heterojunction grown on 6H-SiC

    SciTech Connect

    Li, L. B.; Chen, Z. M.; Zang, Y.

    2015-01-07

    The Si/SiC heterojunctions were prepared on 6H-SiC (0001) C-face by low-pressure chemical vapour deposition at 850 ∼ 1050 °C. Transmission electron microscopy and selected area electron diffraction were employed to investigate the interface-structure of Si/SiC heterojunctions. The Si/6H-SiC heterostructure of large lattice-mismatch follows domain matching epitaxy mode, which releases most of the lattice-mismatch strain, and the coherent Si epilayers can be grown on 6H-SiC. Si(1-11)/6H-SiC(0001) heterostructure is obtained at 900 °C, and the in-plane orientation relationship of Si/6H-SiC heterostructure is (1–11)[1-1-2]{sub Si}//(0001)[-2110]{sub 6H-SiC}. The Si(1-11)/6H-SiC(0001) interface has the same 4:5 Si-to-SiC matching mode with a residual lattice-mismatch of 0.26% along both the Si[1-1-2] and Si[110] orientations. When the growth temperature increases up to 1000 °C, the 〈220〉 preferential orientation of the Si film appears. SAED patterns at the Si/6H-SiC interface show that the in-plane orientation relationship is (-220)[001]{sub Si}//(0001)[2-1-10]{sub 6H-SiC}. Along Si[110] orientation, the Si-to-SiC matching mode is still 4:5; along the vertical orientation Si[001], the Si-to-SiC mode change to approximate 1:2 and the residual mismatch is 1.84% correspondingly. The number of the atoms in one matching-period decreases with increasing residual lattice-mismatch in domain matching epitaxy and vice versa. The Si film grows epitaxially but with misfit dislocations at the interface between the Si film and the 6H-SiC substrate. And the misfit dislocation density of the Si(1-11)/6H-SiC(0001) and Si(-220)/6H-SiC(0001) obtained by experimental observations is as low as 0.487 × 10{sup 14 }cm{sup −2} and 1.217 × 10{sup 14 }cm{sup −2}, respectively, which is much smaller than the theoretical calculation results.

  19. ULS Joint Committee to Study Library Periodical Services. Final Report.

    ERIC Educational Resources Information Center

    Hirshon, Arnold; And Others

    Developed in response to issues raised about the circulation of bound periodicals, the cost of photocopies, and the condition of the photocopiers, this report of the Joint Committee to Study Library Periodical Services at the Virginia Commonwealth University libraries recommends goals for periodicals services for both campuses of the university.…

  20. Trisodium citrate, Na3(C6H5O7)

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2016-01-01

    The crystal structure of anhydrous tris­odium citrate, Na3(C6H5O7), has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory (DFT). There are two independent five-coordinate Na+ and one six-coordinate Na+ cations in the asymmetric unit. The [NaO5] and [NaO6] polyhedra share edges and corners to form a three-dimensional framework. There are channels parallel to the a and b axes in which the remainder of the citrate anions reside. The only hydrogen bonds are an intra­molecular one between the hy­droxy group and one of the terminal carboxyl­ate O atoms and an intermolecular one between a methylene group and the hydroxyl O atom. PMID:27308044

  1. Deformation behaviour and 6H-LPSO structure formation at nanoindentation in lamellar high Nb containing TiAl alloy

    NASA Astrophysics Data System (ADS)

    Song, L.; Xu, X. J.; Peng, C.; Wang, Y. L.; Liang, Y. F.; Shang, S. L.; Liu, Z. K.; Lin, J. P.

    2015-02-01

    Microstructure and deformation mechanisms at a nanoindentation in the lamellar colony of high Nb containing TiAl alloy have been studied using the focused ion beam and the transmission electron microscopy. Considerable deformation twins are observed around the nanoindentation, and a strain gradient is generated. A continuous change in the bending angle of the lamellar structure can be derived, and a strain-induced grain refinement process is observed as various active deformations split the γ grains into subgrains. In addition to all possible deformation mechanisms (ordinary dislocation, super-dislocation and deformation twining) activated due to the heavy plastic deformation, a 6-layer hexagonal (6H) long-period stacking ordered structure is identified for the first time near the contact zone and is thought to be closely related to the glide of partial dislocations.

  2. Investigation of the transition layer in 3C-SiC/6H-SiC heterostructures

    SciTech Connect

    Lebedev, A. A.; Zamorianskaya, M. V.; Davydov, S. Yu.; Kirilenko, D. A.; Lebedev, S. P. Sorokin, L. M.; Shustov, D. B.; Scheglov, M. P.

    2013-11-15

    Transmission electron microscopy and the cathodoluminescence method are used to study the transition region in 3C-SiC/6H-SiC heterostructures. It is shown that this region is, as a rule, constituted by alternating 3C-SiC and 6H-SiC layers with the possible inclusion of other silicon carbide polytypes. An assumption is made that this structure of the transition region can be explained in terms of the model of spinodal decomposition.

  3. Does the metal-metal sextuple bond exist in the bimetallic sandwich compounds Cr2(C6H6)2, Mo2(C6H6)2, and W2(C6H6)2?†

    NASA Astrophysics Data System (ADS)

    Sun, Zhi; Schaefer, Henry F., III; Xie, Yaoming; Liu, Yongdong; Zhong, Rugang

    2013-09-01

    Although evanescent at best, the bare dimers of the elements Cr, Mo, and W have been identified as possible candidates for the sextuple metal-metal bond. The corresponding dibenzene sandwich compounds Cr2(C6H6)2, Mo2(C6H6)2, and W2(C6H6)2, satisfy the '18-Electron Rule', and might achieve high-order metal-metal bonds and longer lifetimes at the same time. Twenty-two different DFT methods have been used to evaluate this possibility. Based on the present Wiberg bond index and molecular orbital analyses, however, only quadruple metal-metal bonds are predicted for the electronic ground states of Cr2(C6H6)2, Mo2(C6H6)2, and W2(C6H6)2, rather than the sextuple or even quintuple bonds, for both singlet and triplet electronic states. It is possible to force the hypothesised D 6h sextuple bond electron configuration, but the resulting energy is 39 kcal/mol above the D 2h quadruple bond structure for Cr2(C6H6)2. However, the constrained sextuple bond structure for Mo2(C6H6)2 lies 19 kcal/mol above the Mo?Mo singlet. For W2(C6H6)2 the sextuple bond structure is predicted to lie only 3 kcal/mol above the W?W structure. Thus the answer to the question raised in our title is 'almost' for the tungsten-sextuple bond.

  4. Synergistic Effects of Iodine and Silver Ions Co-Implanted in 6H-SiC

    SciTech Connect

    Kuhudzai, Remeredzai J.; Malherbe, Johan; Hlatshwayo, T. T.; van der Berg, N. G.; Devaraj, Arun; Zhu, Zihua; Nandasiri, Manjula I.

    2015-10-23

    Motivated by the aim of understanding the release of fission products through the SiC coating of fuel kernels in modern high temperature nuclear reactors, a fundamental investigation is conducted to understand the synergistic effects of implanted silver (Ag) and iodine (I) in 6H-SiC. The implantation of the individual species, as well as the co-implantation of 360 keV ions of I and Ag at room temperature in 6H-SiC and their subsequent annealing behavior has been investigated by Secondary Ion Mass Spectrometry (SIMS), Atom Probe Tomography (APT) and X-ray Photoelectron Spectroscopy (XPS). SIMS and APT measurements indicated the presence of Ag in the co-implanted samples after annealing at 1500 ºC for 30 hours in sharp contrast to the samples implanted with Ag only. In samples implanted with Ag only, complete loss of the implanted Ag was observed. However, for I only implanted samples, some iodine was retained. APT of annealed co-implanted 6H-SiC showed clear spatial association of Ag and I clusters in SiC, which can be attributed to the observed I assisted retention of Ag after annealing. Such detailed studies will be necessary to identify the fundamental mechanism of fission products migration through SiC coatings.

  5. MECAR operation during the 6/95 study period

    SciTech Connect

    Capista, Dave; /Fermilab

    1995-01-01

    The MECAR system was scheduled to be used 36 hours during the study period. In practice the system was used a bit more since there is increasing pressure to switch completely over to MECAR. During this period of MECAR operation there were power supply studies, tune calibration, general tune-up with this system, and identification and some repair of bugs found in both the applications program and the MECAR operating system.

  6. A novel one-pot synthesis of heterocyclic compound (4-benzoyl-5-phenyl-2-(pyridin-2-yl)-3,3a-dihydropyrazolo[1,5-c]pyrimidin-7(6H)-one): Structural (X-ray and DFT) and spectroscopic (FT-IR, NMR, UV-Vis and Mass) characterization Studies

    NASA Astrophysics Data System (ADS)

    Özdemir, Mecit; Sönmez, Mehmet; Şen, Fatih; Dinçer, Muharrem; Özdemir, Namık

    2015-02-01

    In this study, the title compound named as 4-benzoyl-5-phenyl-2-(pyridin-2-yl)-3,3a-dihydropyrazolo[1,5-c]pyrimidin-7(6H)-one (C24H18N4O2) was both experimentally and theoretically investigated. The compound was synthesized and characterized by FT-IR, NMR (1H NMR, 13C NMR and HETCOR-NMR), Mass spectroscopies and single-crystal X-ray diffraction methods. The compound crystallizes in the monoclinic space group P21/n with a = 6.1402 (3) Å, b = 21.4470 (15) Å, c = 15.0049 (8) Å and β = 97.407 (4)°. The molecular geometry was obtained from the X-ray structure determination optimized using density functional theory (DFT/B3LYP) method with the 6-31+G(d, p) basis set in ground state. From the optimized structure, geometric parameters, vibrational wavenumbers and chemical shifts of molecule were obtained. Experimental measurements were compared with its corresponding the calculated data. An excellent harmony between the two data was ascertained. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs) and non-linear optical (NLO) properties of the title molecule were investigated by theoretical calculations at the B3LYP/6-31+G(d, p) level.

  7. Solvent effect on infrared spectra of methyl methacrylate in CCl4/C6H14, CHCl3/C6H14 and C2H5OH/C6H14 binary solvent systems.

    PubMed

    Zheng, Jianping; Liu, Qing; Zhang, Hui; Fang, Danjun

    2004-11-01

    Research of methyl methacrylate (MMA) in three kinds of binary solvent systems (CCl4/C6H14, CHCl3/C6H14 and C2H5OH/C6H14) on the infrared (IR) spectra was reported. Two types of carbonyl stretching vibration bands for MMA in CHCl3/C6H14 or C2H5OH/C6H14 mixtures were found with the changing of the mole fraction of CHCl3 (XCHCl3) or C2H5OH (XC2H5OH). The carbonyl stretching vibration bands at lower frequencies in the above two mixtures were attributed to the formation of hydrogen bonding between MMA and CHCl3 or C2H5OH. While in CCl4/C6H14 mixtures there was only one type of carbonyl stretching vibration band of MMA. Good linear correlations between the frequencies of C=O or C=C stretching vibration band of MMA and XCCl4, XCHCl3 or XC2H5OH were found, respectively. The solute-solvent interactions in the three different binary solvent systems were discussed in detail.

  8. Conformational Isomerism of trans-[Pt(NH2C6H11)2I2] and the Classical Wernerian Chemistry of [Pt(NH2C6H11)4]X2 (X = Cl, Br, I)1

    PubMed Central

    Johnstone, Timothy C.; Lippard, Stephen J.

    2012-01-01

    X-ray crystallographic analysis of the compound trans-[Pt(NH2C6H11)2I2] revealed the presence of two distinct conformers within one crystal lattice. This compound was studied by variable temperature NMR spectroscopy to investigate the dynamic interconversion between these isomers. The results of this investigation were interpreted using physical (CPK) and computational (molecular mechanics and density functional theory) models. The conversion of the salts [Pt(NH2C6H11)4]X2 into trans-[Pt(NH2C6H11)2X2] (X = Cl, Br, I) was also studied and is discussed here with an emphasis on parallels to the work of Alfred Werner. PMID:23554544

  9. Multihormonal regulation of thyroglobulin production by the OVNIS 6H thyroid cell line.

    PubMed

    Aouani, A; Hovsépian, S; Fayet, G

    1988-02-01

    The hormonal regulation of thyroglobulin production has been studied using a clone of the ovine thyroid cell line: OVNIS 6H. 3 among the 6 hormones proposed for serum replacement are required for an optimal thyroglobulin production; insulin, hydrocortisone and thyrotropin. Insulin alone stimulates thyroglobulin production. The presence of insulin is also required to observe hydrocortisone and TSH stimulations. Newborn calf serum inhibits thyroglobulin production. The best conditions for optimal thyroglobulin expression and TSH responsiveness are obtained in serum-free medium supplemented with 5 micrograms/ml insulin, 100 nM hydrocortisone and 1 mU/ml TSH.

  10. ACLCP Periodical Storage Center: Feasibility Study, September 1974-April 1975.

    ERIC Educational Resources Information Center

    Cieslicki, Dorothy

    A study of alternative models for establishing a cooperative storage center for little used library materials by the members of the Area College Libraries of Central Pennsylvania (ACLCP) focused on periodicals. Considerations discussed include advantages--lower cost; space for growth and better access to holdings retained in active collections;…

  11. C6H5NH2 effect on the corrosion inhibition of aluminium in 0.5 M HCl

    NASA Astrophysics Data System (ADS)

    Omotosho, Olugbenga Adeshola; Okeniyi, Joshua Olusegun; Loto, Cleophas Akintoye; Popoola, Abimbola Patricia Idowu; Fademi, Ekundayo Oluwademilade Jacob; Oladipupo, Segun Isaac; Alabi, Ayomide Samuel; Ajibola, Omokolade Bamidele; Emelieze, Alex Nwabunor

    2017-02-01

    In this paper, C6H6NH2 (aniline) effect on the corrosion of aluminium in 0.5 M (i.e. mol/L) HCl medium was studied using gravimetric method by weight loss measurements and electrochemical technique of corrosion potential and potentiodynamic polarization by cyclic voltamery (CV) instrumentation. By these techniques, corrosion rate obtained from aluminium specimens, in 0.5 HCl test-solution having different concentrations of the hydrogen-containing C6H6NH2 chemical, were requisitely analysed. Results showed that the potentiodynamic corrosion rate excellently correlated (R = 98.94%, Nash-Sutcliffe efficiency = 97.89% and ANOVA p-value = 0.0314) with function of the gravimetric corrosion rate and C6H5NH2 concentration. Both experimental and correlated prediction models identified 0.043 mol/L C6H5NH2 with optimal inhibition efficiency performance η = 84.11% by the experimental or η = 81.15% by the predicted models. Fittings of experimental and correlated data showed the data models followed the Langmuir adsorption isotherm from which favourable adsorption and prevalent physisorption were indicated as the C6H5NH2 corrosion-protection on aluminium metal in the 0.5 M HCl medium.

  12. Studies of the Long Secondary Periods in Pulsating Red Giants

    NASA Astrophysics Data System (ADS)

    Percy, J. R.; Deibert, E.

    2016-12-01

    We have used systematic, sustained visual observations from the AAVSO International Database and the AAVSO time-series analysis package VSTAR to study the unexplained "long secondary periods" (LSPs) in 27 pulsating red giants. In our sample, the LSPs range from 479 to 2967 days, and are on average 8.1 +/- 1.3 times the excited pulsation period. There is no evidence for more than one LSP in each star. In stars with both the fundamental and first overtone radial period present, the LSP is more often about 10 times the latter. The visual amplitudes of the LSPs are typically 0.1 magnitude and do not correlate with the LSP. The phase curves tend to be sinusoidal, but at least two are sawtooth. The LSPs are stable, within their errors, over the timespan of our data, which is typically 25,000 days. The amplitudes, however, vary by up to a factor of two or more on a time scale of roughly 20-30 LSPs. There is no obvious difference between the carbon (C) stars and the normal oxygen (M) stars. Previous multicolor observations showed that the LSP color variations are similar to those of the pulsation period, and of the LSPs in the Magellanic Clouds, and not like those of eclipsing stars. We note that the LSPs are similar to the estimated rotation periods of the stars, though the latter have large uncertainties. This suggests that the LSP phenomenon may be a form of modulated rotational variability.

  13. Nqrs Data for C6H16I2N4O8 [C6H14N4O2·2(HIO3)] (Subst. No. 0932)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H16I2N4O8 [C6H14N4O2·2(HIO3)] (Subst. No. 0932)

  14. Nqrs Data for C6H16I2N2O8 [C6H14N2O2·2(HIO3)] (Subst. No. 0931)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H16I2N2O8 [C6H14N2O2·2(HIO3)] (Subst. No. 0931)

  15. Nqrs Data for C6H20I6N2O20 [C6H14N2O2·6(HIO3)] (Subst. No. 0939)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H20I6N2O20 [C6H14N2O2·6(HIO3)] (Subst. No. 0939)

  16. Nqrs Data for C6H17I3N2O11 [C6H14N2O2·3(HIO3)] (Subst. No. 0933)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H17I3N2O11 [C6H14N2O2·3(HIO3)] (Subst. No. 0933)

  17. Optical spectroscopy of ZnSiF6·6H2O:Mn4+ red phosphor

    NASA Astrophysics Data System (ADS)

    Hoshino, Ryosuke; Adachi, Sadao

    2013-12-01

    We report on a method of synthesizing Mn4+-activated ZnSiF6.6H2O hydrate phosphor by the chemical reaction in a Teflon beaker. The structural and optical properties of ZnSiF6.6H2O:Mn4+ are investigated using x-ray diffraction measurement, photoluminescence (PL) analysis, PL excitation spectroscopy, diffuse reflectance measurement, and Raman scattering spectroscopy. The synthesized phosphor exhibits a series of sharp red emission peaks at ˜630 nm, which is characteristic for Mn4+ ions. The luminescent study is focused on the thermal quenching phenomenon above ˜300 K and is found to be caused by thermal decomposition of the ZnSiF6.6H2O host. Degradation in the PL intensity under near-UV light illumination has also been observed to occur in this phosphor.

  18. Preparation and biodistribution of copper-67-labeled porphyrins and porphyrin-A6H immunoconjugates.

    PubMed

    Bhalgat, M K; Roberts, J C; Mercer-Smith, J A; Knotts, B D; Vessella, R L; Lavallee, D K

    1997-02-01

    The synthetic porphyrins, N-benzyl-5,10,15,20-tetrakis (4-carboxyphenyl) porphine (N-bzHTCPP) and N-4-nitrobenzyl-5-(4-carboxyphenyl)-10,15,20-tris(4-sulfophenyl) porphine (N-bzHCS3P), represent excellent radiocopper chelating agents that may find utility in antibody-mediated diagnosis and/or therapy. N-bzHCS3P was conjugated to an anti-renal cell carcinoma (RCC) antibody, A6H, and labeled with copper-67. 67CuCS3P-A6H was studied for its biodistribution in human RCC xenograft-bearing nude mice, along with the radiolabeled free porphyrins. The porphyrins resulted in tumor:blood ratios in the range of 3 to 4 after 48 h. The radiolabeled antibody achieved a tumor:blood ratio of over 16 after 45 h, indicating accumulation at the desired site. However, unwanted localization also occurred in the liver and spleen, which will have to be rectified before realizing the full potential of this approach.

  19. {alpha}- to {beta}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10} reversible solid-state transition, thermochromic and optical studies in the p-phenylenediamine-based iodobismuthate(III) material

    SciTech Connect

    Hrizi, Chakib; Trigui, Ameni; Abid, Younes; Chniba-Boudjada, Nassira; Bordet, Pierre; Chaabouni, Slaheddine

    2011-12-15

    {alpha}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10}, which is a new material containing low-dimensional iodobismuthate anions, was synthesized and through its single crystal X-ray diffraction measurements, was proven to crystallize at room temperature in the centrosymmetric space group P2{sub 1}/c. It consists of a p-phenylenediammonium dication and a discrete (0-D) anion built up of edge-sharing bioctahedron. Due to the hydrogen bonds and the interatomic distances (Bi-I, I Midline-Horizontal-Ellipsis I and {pi}-{pi}) changes, {alpha}-phase was transformed into the corresponding centrosymmetric {beta}-phase, {beta}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10}, through a single-crystal to single-crystal transformation occurring upon cooling to -28/-26 Degree-Sign C. Below the transition temperature, {beta}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10} crystallizes in the monoclinic system, centrosymmetric space group P2{sub 1}/n. Besides, the optical transmission measurements on {alpha}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10} thin films have revealed two absorption bands at 2.47 and 3.01 eV. Finally, two room temperature photoluminescence emissions attributed to excitons radiative recombinations confined within the bioctahedra Bi{sub 2}I{sub 10}{sup 4-}, were observed in the red spectral range at 1.9 and 2.05 eV energy. - Graphical abstract: The structure of {alpha}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10} consists of p-phenylenediammonium dications and dimeric decaiododibismuthate tetraanions stacked in a chessboard fashion. The optical properties were investigated by optical absorption and photoluminescence measurements. Highlights: Black-Right-Pointing-Pointer {alpha}-[C{sub 6}H{sub 4}(NH{sub 3}){sub 2}]{sub 2}Bi{sub 2}I{sub 10} is a new material containing low-dimensional iodobismuthate anions. Black-Right-Pointing-Pointer Below -35 Degree-Sign C {alpha}-phase undergoes

  20. Fabrication and Characterization of 6H-SiC Switching Devices

    DTIC Science & Technology

    1993-06-01

    ns range at 623 K has been observed in a 6H- SiC pn junction diode[4]. A Pt/6H-SiC Schottky diode has been shown to have 400 V reverse breakdown...6H-SiC Schottky diode switches, and a 75% switching efficiency in p+n 6H-SiC diode switches. A breakdown field of more than 1x106 V /cm is obtained...This could mean a blocking voltage of about 3000 v . A number of successful sic devices has been demonstrated. A high temperature rectifier made

  1. The first potential energy surfaces for the C6H--H2 and C6H--He collisional systems and their corresponding inelastic cross sections

    NASA Astrophysics Data System (ADS)

    Walker, Kyle M.; Dumouchel, Fabien; Lique, François; Dawes, Richard

    2016-07-01

    Molecular anions have recently been detected in the interstellar and circumstellar media. Accurate modeling of their abundance requires calculations of collisional data with the most abundant species that are usually He atoms and H2 molecules. In this paper, we focus on the collisional excitation of the first observed molecular anion, C6H-, by He and H2. Theoretical calculations of collisional cross sections rely generally on ab initio interaction potential energy surfaces (PESs). Hence, we present here the first PESs for the C6H--H2 and C6H--He van der Waals systems. The ab initio energy data for the surfaces were computed at the explicitly correlated coupled cluster with single, double, and scaled perturbative triple excitations level of theory. The method of interpolating moving least squares was used to construct 4D and 2D analytical PESs from these data. Both surfaces are characterized by deep wells and large anisotropies. Analytical models of the PESs were used in scattering calculations to obtain cross sections for low-lying rotational transitions. As could have been anticipated, important differences exist between the He and H2 cross sections. Conversely, no significant differences exist between the collisions of C6H- with the two species of H2 (para- and ortho-H2). We expect that these new data will help in accurately determining the abundance of the C6H- anions in space.

  2. Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4356_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4356_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  3. Volumetric Properties of the Mixture Butyl ethanoate C6H12O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1412, LB4315_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Butyl ethanoate C6H12O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1412, LB4315_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  4. Volumetric Properties of the Mixture 2-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4354_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4354_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  5. Volumetric Properties of the Mixture 3-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4359_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 3-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4359_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  6. Volumetric Properties of the Mixture Butyl ethanoate C6H12O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1511, LB4138_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Butyl ethanoate C6H12O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1511, LB4138_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  7. Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4358_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4358_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  8. Volumetric Properties of the Mixture 3-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4355_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 3-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4355_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  9. Volumetric Properties of the Mixture 2,3-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4360_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2,3-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4360_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  10. Volumetric Properties of the Mixture 2-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4361_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2-Methylpentane C6H14 + C6H14O Hexan-1-ol (VMSD1412, LB4361_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  11. Volumetric Properties of the Mixture 2,3-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4357_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2,3-Dimethylbutane C6H14 + C6H14O Hexan-1-ol (VMSD1511, LB4357_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  12. Volumetric Properties of the Mixture Benzene C6H6 + C6H10O Cyclohexanone (VMSD1111, LB4819_V0029

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Benzene C6H6 + C6H10O Cyclohexanone (VMSD1111, LB4819_V)' providing data from direct low-pressure measurement of mass density at variable mole fraction and constant temperature, in the single-phase region(s).

  13. Vapor-Liquid Equilibrium in the Mixture Cyclohexanone C6H10O + C6H12O Cyclohexanol (EVLM1111, LB5657_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Cyclohexanone C6H10O + C6H12O Cyclohexanol (EVLM1111, LB5657_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

  14. Heat of Mixing and Solution of Cyclohexanone C6H10O + C6H12O Cyclohexanol (HMSD1121, LB4187_H)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Heat of Mixing and Solution of Cyclohexanone C6H10O + C6H12O Cyclohexanol (HMSD1121, LB4187_H)' providing data from direct calorimetric measurement of molar excess enthalpy at variable mole fraction and constant pressure and temperature.

  15. Volumetric Properties of the Mixture Benzene C6H6 + C6H10O Cyclohexanone (VMSD1511, LB4829_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Benzene C6H6 + C6H10O Cyclohexanone (VMSD1511, LB4829_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  16. Volumetric Properties of the Mixture Benzene C6H6 + C6H10O Cyclohexanone (VMSD1212, LB4824_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Benzene C6H6 + C6H10O Cyclohexanone (VMSD1212, LB4824_V)' providing data by calculation of molar excess volume from low-pressure density measurements at variable mole fraction and constant temperature.

  17. Heat of Mixing and Solution of Hexane C6H14 + C6H18OSi2 Hexamethyldisiloxane (HMSD1111, LB4099_H)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Heat of Mixing and Solution of Hexane C6H14 + C6H18OSi2 Hexamethyldisiloxane (HMSD1111, LB4099_H)' providing data from direct low-pressure calorimetric measurement of molar excess enthalpy at variable mole fraction and constant temperature.

  18. Formation of cobalt disilicide films on (3×3)6H-SiC(0001)

    NASA Astrophysics Data System (ADS)

    Platow, W.; Wood, D. K.; Tracy, K. M.; Burnette, J. E.; Nemanich, R. J.; Sayers, D. E.

    2001-03-01

    This paper presents a detailed study of thin Co films grown directly, sequentially, and by codeposition with Si on the (3×3)-R30° surface of 6H-SiC(0001). The structure, chemistry, and morphology of the films were determined using x-ray absorption fine structure, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and atomic force microscopy. For directly deposited Co films (1-8 nm) graphite layers form on top of the film surface during annealing, whereas Co stays mainly unreacted over a temperature range of 300-1000 °C. The formation of CoSi2 is achieved by sequential and codeposition of Co and Si. Films annealed at 550 °C are polycrystalline and further annealing to 650 °C causes no C segregation, but there is islanding of the films. Attempts to improve film morphology and homogeneity including applying a template method and varying growth temperature are also reported.

  19. Primary photoluminescence in as-neutron (electron) -irradiated n-type 6H-SiC

    NASA Astrophysics Data System (ADS)

    Zhong, Z. Q.; Wu, D. X.; Gong, M.; Wang, O.; Shi, S. L.; Xu, S. J.; Chen, X. D.; Ling, C. C.; Fung, S.; Beling, C. D.; Brauer, G.; Anwand, W.; Skorupa, W.

    2006-05-01

    Low-temperature photoluminescence spectroscopy has revealed a series of features labeled S1, S2, S3 in n-type 6H-SiC after neutron and electron irradiation. Thermal annealing studies showed that the defects S1, S2, S3 disappeared at 500 °C. However, the well-known D1 center was only detected for annealing temperatures over 700 °C. This experimental observation not only indicated that the defects S1, S2, S3 were a set of primary defects and the D1 center was a kind of secondary defect, but also showed that the D1 center and the E1, E2 observed using deep level transient spectroscopy might not be the same type of defects arising from the same physical origin.

  20. Anomalous behaviors of E1/E2 deep level defects in 6H silicon carbide

    NASA Astrophysics Data System (ADS)

    Chen, X. D.; Ling, C. C.; Gong, M.; Fung, S.; Beling, C. D.; Brauer, G.; Anwand, W.; Skorupa, W.

    2005-01-01

    Deep level defects E1/E2 were observed in He-implanted, 0.3 and 1.7MeV electron-irradiated n-type 6H-SiC. Similar to others' results, the behaviors of E1 and E2 (like the peak intensity ratio, the annealing behaviors or the introduction rates) often varied from sample to sample. This anomalous result is not expected of E1/E2 being usually considered arising from the same defect located at the cubic and hexagonal sites respectively. The present study shows that this anomaly is due to another DLTS peak overlapping with the E1/E2. The activation energy and the capture cross section of this defect are EC-0.31eV and σ ˜8×10-14cm2, respectively.

  1. Blue photoluminescence enhancement in laser-irradiated 6H-SiC at room temperature

    SciTech Connect

    Wu, Yan; Ji, Lingfei Lin, Zhenyuan; Jiang, Yijian; Zhai, Tianrui

    2014-01-27

    Blue photoluminescence (PL) of 6H-SiC irradiated by an ultraviolet laser can be observed at room temperature in dark condition. PL spectra with Gaussian fitting curve of the irradiated SiC show that blue luminescence band (∼440 nm) is more pronounced than other bands. The blue PL enhancement is the combined result of the improved shallow N-donor energy level and the unique surface state with Si nanocrystals and graphene/Si composite due to the effect of photon energy input by the short-wavelength laser irradiation. The study can provide a promising route towards the preparation of well-controlled blue photoluminescence material for light-emitting devices.

  2. Nitrogen-related point defect in 4H and 6H SiC

    NASA Astrophysics Data System (ADS)

    Zvanut, M. E.; van Tol, J.

    2007-12-01

    A nitrogen-related pair defect is studied as a function of doping density in 4H and 6H SiC. Electron paramagnetic resonance measurements verify that one nucleus in the pair is nitrogen, but the second part of the pair remains uncertain. The pair concentration varies monotonically with nitrogen concentration in samples with doping density 10 18-10 16 cm -3 and the boron concentration is an order of magnitude less than that of nitrogen. The pair center is not observed in the dark or under ultraviolet illumination when the nitrogen and boron concentrations are similar. We conclude that the pair is generated in all nitrogen-doped samples, but like the isolated nitrogen impurity, may be compensated by boron.

  3. Time-course of cerebral perfusion and tissue oxygenation in the first 6 h after experimental subarachnoid hemorrhage in rats.

    PubMed

    Westermaier, Thomas; Jauss, Alina; Eriskat, Jörg; Kunze, Ekkehard; Roosen, Klaus

    2009-04-01

    Present knowledge about hemodynamic and metabolic changes after subarachnoid hemorrhage (SAH) originates from neuromonitoring usually starting with aneurysm surgery and animal studies that have been focusing on the first 1 to 3 h after SAH. Most patients, however, are referred to treatment several hours after the insult. We examined the course of hemodynamic parameters, cerebral blood flow, and tissue oxygenation (ptiO2) in the first 6 h after experimental SAH. Sixteen Sprague-Dawley rats were subjected to SAH using the endovascular filament model or served as controls (n=8). Bilateral local cortical blood flow, intracranial pressure, cerebral perfusion pressure, and ptiO2 were followed for 6 h after SAH. After induction of SAH, local cortical blood flow rapidly declined to 22% of baseline and returned to 80% after 6 h. The decline of local cortical blood flow markedly exceeded the decline of cerebral perfusion pressure. ptiO2 declined to 57%, recovered after 2 h, and reached > or =140% of baseline after 6 h. Acute vasoconstriction after SAH is indicated by the marked discrepancy of cerebral perfusion pressure and local cortical blood flow. The excess tissue oxygenation several hours after SAH suggests disturbed oxygen utilization and cerebral metabolic depression. Aside from the sudden increase of intracranial pressure at the time of hemorrhage and delayed cerebral vasospasm, the occurrence of acute vasoconstriction and disturbed oxygen utilization may be additional factors contributing to secondary brain damage after SAH.

  4. A novel periodic boundary condition for computational hemodynamics studies.

    PubMed

    Bahramian, Fereshteh; Mohammadi, Hadi

    2014-07-01

    In computational fluid dynamics models for hemodynamics applications, boundary conditions remain one of the major issues in obtaining accurate fluid flow predictions. For major cardiovascular models, the realistic boundary conditions are not available. In order to address this issue, the whole computational domain needs to be modeled, which is practically impossible. For simulating fully developed turbulent flows using the large eddy simulation and dynamic numerical solution methods, which are very popular in hemodynamics studies, periodic boundary conditions are suitable. This is mainly because the computational domain can be reduced considerably. In this study, a novel periodic boundary condition is proposed, which is based on mass flow condition. The proposed boundary condition is applied on a square duct for the sake of validation. The mass-based condition was shown to obtain the solution in 15% less time. As such, the mass-based condition has two decisive advantages: first, the solution for a given Reynolds number can be obtained in a single simulation because of the direct specification of the mass flow, and second, simulations can be made more quickly.

  5. Hypokalaemic Periodic Paralysis– A Prospective Study of the Underlying Etiologies

    PubMed Central

    Jandhyala, Surya Narayana; Belle, Jayaprakash; Rau, N.R; Shetty, Ranjan

    2015-01-01

    Background Hypokalaemic periodic paralysis (HPP) is a rare muscular disorder characterised by episodic weakness associated with hypokalaemia. The disease can either be inherited or acquired and misdiagnosis of the disease is quite common. Most of the data available on the disease is from the western world. Studies reporting aetiological, clinical and metabolic profiles of Indian population are sparse. Hence we tried to provide insights of the disease among the Indian population. Aim To study the aetiological, clinical and metabolic profile of patients diagnosed with Hypokalaemic Periodic Paralysis (HPP). Materials and Methods This is an observational and analytical study on HPP diagnosed patients, during September 2011 to September 2014 in Kasturba Hospital, Manipal. A total of 23 patients were studied. Detailed history, clinical evaluation and metabolic workup for secondary causes of HPP were analysed. Results Of the 23 patients, 57% had primary HPP while 43% had secondary HPP. The group of patients with primary HPP comprised of 92% males and 8% females with mean age of 28 years and the mean duration of symptoms of 18 hours. The group with secondary HPP comprised of 70% males and 30% females with mean age of 38.7 years and the mean duration of symptoms of 60 hours. The secondary causes of HPP were thyrotoxicosis (50%), infective diarrhea (20%), Crohn’s disease (10%), renal tubular acidosis (RTA) Type I (10%) and Conn’s syndrome (10%). Conclusion In our study primary HPP was found to be more common than secondary HPP. Males were predominantly affected in both groups. HPP should be ruled out before starting therapy for Guillain-Barré Syndrome (GBS). PMID:26500936

  6. Synthesis, spectra, and theoretical investigations of the triarylamines based on 6H-indolo[2,3-b]quinoxaline.

    PubMed

    Thomas, K R Justin; Tyagi, Payal

    2010-12-03

    Triarylamines containing a 6H-indolo[2,3-b]quinoxaline core and aromatic units such as phenyl, naphthyl, pyrene, anthracene, or fluorene have been synthesized by employing palladium-catalyzed C-N and C-C coupling reactions and characterized by optical absorption and emission spectra, electrochemical behavior, and thermal studies. Even though the electronic absorption spectra of the compounds were influenced by the nature of the peripheral amines, the emission spectra indicated close similarity for the excited states in these compounds. For the derivatives in which the amines were directly anchored on the 6H-indolo[2,3-b]quinoxaline nucleus, the emission appeared to be dominated by the state localized on the 6H-indolo[2,3-b]quinoxaline chromophore, while in the compounds containing the extended conjugation the fluorescence originated from the polyaromatic linker. The compounds displayed green or yellow emission depending on the nature of the amine segment. All of the dyes displayed one-electron quasi-reversible oxidation couple in the cyclic voltammograms, which is attributable to the oxidation of the peripheral amines at the 6H-indolo[2,3-b]quinoxaline core. An additional one-electron oxidation process observable at the high positive potentials for the compounds 7 and 8 probably arises from the oxidation of the arylthiophene segment. The enhanced thermal stability and relatively higher glass transition temperatures observed for these compounds were attributed to the presence of dipolar 6H-indolo[2,3-b]quinoxaline segment. The origin of the optical spectra and the trends observed therein were rationalized using TDDFT simulations.

  7. Experimental study of periodic flow effects on spanwise vortex

    NASA Astrophysics Data System (ADS)

    Garcia Molina, Cruz Daniel; Lopez Sanchez, Erick Javier; Ruiz Chavarria, Gerardo; Medina Ovando, Abraham

    2014-11-01

    We present an experimental study about the spanwise vortex produced in a flow going out of a channel in shallow waters. This vortex travels in front of the dipole. The velocity field measurement was done using the PIV technique, and DPIVsoft (https://www.irphe.fr/ ~meunier/) was used for data processing. In this case the flow has a periodic forcing to simulate ocean tides. The experiment was conducted in a channel with variable width and the measurements were made using three different values of the aspect ratio width-depth. We present results of the position, circulation of this spanwise vortex and the flow inversion effect. The change of flow direction modify the intensity of the vortex, but it does not destroy it. The vertical components of the velocity field contributes particle transport. G. Ruiz Chavarria, E. J. Lopez Sanchez and C. D. Garcia Molina acknowledge DGAPA-UNAM by support under project IN 116312 (Vorticidad y ondas no lineales en fluidos).

  8. A Period Study of the Close Binary V508 Ophiuchi

    NASA Astrophysics Data System (ADS)

    Albayrak, Berahitdin

    The short-period (0d.34) close binary V508 Oph was observed in 2005 and four new times of minima were derived. All of the available times of minima, including the new ones, covering 69 years were analyzed. It was shown that the period change of the system is very complex. Two possible period oscillations with periods of 24.73 and 9.91 years and amplitudes of about 0.011 and 0.002 day, respectively, were found to superimpose on upward parabolic change, indicating a secular period increase at a rate of dp/dt = 4.24 × 10-9 days yr-1. The mechanisms that could explain the period changes of the system are discussed.

  9. A study of periodic and aperiodic ferromagnetic antidot lattices

    NASA Astrophysics Data System (ADS)

    Bhat, Vinayak S.

    This thesis reports our study of the effect of domain wall pinning by ferromagnetic (FM) metamaterials [1] in the form of periodic antidot lattices (ADL) on spin wave spectra in the reversible regime. This study was then extended to artificial quasicrystals in the form of Penrose P2 tilings (P2T). Our DC magnetization study of these metamaterials showed reproducible and temperature dependent knee anomalies in the hysteretic regime that are due to the isolated switching of the FM segments. Our dumbbell model analysis [2] of simulated magnetization maps indicates that FM switching in P2T is nonstochastic . We have also acquired the first direct, two-dimensional images of the magnetization of Permalloy films patterned into P2T using scanning electron microscopy with polarization analysis (SEMPA). Our SEMPA images demonstrate P2T behave as geometrically frustrated networks of narrow ferromagnetic film segments having near-uniform, bipolar (Ising-like) magnetization, similar to artificial spin ices (ASI). We find the unique aperiodic translational symmetry and diverse vertex coordination of multiply-connected P2T induce a more complex spin-ice behavior driven by exchange interactions in vertex domain walls, which differs markedly from the behavior of disconnected ASI governed only by dipolar interactions. Keywords: Ferromagnetic Antidot Lattices, Metamaterials, Ferromagnetic Resonance, Artificial Quasicrystal, Artificial Spin Ice. [1] VV Kruglyak et al. "Magnonic metamaterials". In: Metamaterial, edited by X.-Y. Jiang (InTech, 2012) (2012). [2] Claudio Castelnovo, Roderich Moessner, and Shivaji L Sondhi. "Magnetic monopoles in spin ice". In: Nature 451.7174 (2008), pp. 42--45.

  10. Periodic quantum chemical studies on anhydrous and hydrated acid clinoptilolite.

    PubMed

    Valdiviés Cruz, Karell; Lam, Anabel; Zicovich-Wilson, Claudio M

    2014-08-07

    Periodic quantum chemistry methods as implemented in the crystal09 code were considered to study acid clinoptilolite (HEU framework type), both anhydrous and hydrated. The most probable location of acid sites and water molecules together with other structural details has been the object of particular attention. Calculations were performed at hybrid and pristine DFT levels of theory with a VDZP quality basis set in order to compare performances. It arises that PBE0 provides the best agreement with experimental data as concerns structural features and the most stable Al distribution in the framework. The role of the water molecule distribution in the stability of the systems, the most probable structure that they induce in the material, and their eventual influence on further chemical modification processes, such as dealumination, are discussed in detail. Results show that, apart from the usually considered interactions of water molecules with the zeolite framework, that is, a H-bond with Brönsted acid sites and coordination with framework Al as Lewis ones, it is necessary to consider cooperation of other weaker effects so as to fully understand the hydration effect in this kind of materials.

  11. Lateral Growth Expansion of 4H/6H-SiC m-plane Pseudo Fiber Crystals by Hot Wall CVD Epitaxy

    NASA Technical Reports Server (NTRS)

    Trunek, Andrew J.; Neudeck, Philip G.; Woodworth, Andrew A.; Powell, J. A.; Spry, David J.; Raghothamachar, Balaji; Dudley, Michael

    2011-01-01

    Lateral expansion of small mixed polytype 4H/6H-SiC slivers were realized by hot wall chemical vapor deposition (HWCVD). Small slivers cut from m-oriented ..11..00.. SiC boule slices containing regions of 4H and 6H SiC were exposed to HWCVD conditions using standard silane/propane chemistry for a period of up to eight hours. The slivers exhibited approximately 1500 microns (1.5 mm) of total lateral expansion. Initial analysis by synchrotron white beam x-ray topography (SWBXT) confirms, that the lateral growth was homoepitaxial, matching the polytype of the respective underlying region of the seed sliver.

  12. Quasi-periodic VLF emissions with short-period modulation and their relationship to whistlers: a case study

    NASA Astrophysics Data System (ADS)

    Titova, Elena; Demekhov, Andrei; Kozlovsky, Alexander; Manninen, Jyrki; Pasmanik, Dmitry

    We study properties of quasiperiodic (QP) VLF emissions recorded on December 24, 2011 during the VLF campaign in Northern Finland. The main attention is paid to interrelationships between different characteristic periods in the QP spectra. In particular, we analyze regular variations in the QP repetition intervals (1 - 10 min) during the event from 15:30 to 22 UT, their changes during substorms, and short periodic (several-second) modulation observed within separate QP elements. We explained the variations of periods of QP emissions in terms of the model of auto-oscillation regime of the cyclotron instability in the magnetosphere. During the considered event lasting about 7 hours we observed a regular increase in the time intervals between the QP elements. We relate this increase with weakening of the magnetospheric source of energetic electrons. Significant variations in the QP period occurred during substorms. These variations can be due to a substorm-related increase in the energetic-electron flux and/or due to the precipitation of these electrons into the ionosphere which changes the reflection coefficient of VLF waves. We analyze the fine structure of QP element spectra and reveal the periods related to the time scales of guided propagation of whistler-mode waves along the magnetic field line, which suggests that ducted propagation regime took place for the QP emissions. The periods were about 6--9 s for frequencies 3.5--1.2 kHz respectively, which was similar to the period of almost simultaneously observed two-hop whistlers In the low-frequency part of QP spectra periodic emissions with меньшими periods of about 3 s were observed. Analysis of fine structure of QP elements shows that their formation is affected by both linear effects (i.e., group-velocity dispersion) and nonlinear effects related

  13. Self-assembly of amphiphilic peptide (AF)6H5K15 derivatives: roles of hydrophilic and hydrophobic residues.

    PubMed

    Thota, Naresh; Jiang, Jianwen

    2014-03-13

    A molecular dynamics simulation study is reported to investigate the roles of hydrophilic and hydrophobic residues in the self-assembly of (AF)6H5K15 peptide derivatives. The peptide, as well as water and counterions, are represented by the MARTINI coarse-grained model. The assembly is observed to follow a three-step process: formation of small clusters, large clusters, and micelles. With increasing length of hydrophilic Lys residues in (AF)6H5Kn (n = 10, 15, 20, and 25), assembly capability is found to be reduced with the formation of smaller micelles or the presence of individual peptide chains. Upon replacing Ala by more hydrophobic Phe in AmFnH5K15 (m + n = 12), larger micelles are formed. With increasing length of hydrophobic Phe residues in FnH5K15 (n = 4, 8, 12, and 16), micelle size increases and the morphology shifts from spherical to fiber-like. The simulation study provides mechanistic insight into the crucial roles of hydrophilicity and hydrophobicity in the assembly of (AF)6H5K15 derivatives; it reveals that assembly capability is reduced by increasing hydrophilicity, whereas increasing hydrophobicity leads to morphology transition.

  14. Atomic probe microscopy of 3C SiC films grown on 6H SiC substrates

    NASA Technical Reports Server (NTRS)

    Steckl, A. J.; Roth, M. D.; Powell, J. A.; Larkin, D. J.

    1993-01-01

    The surface of 3C SiC films grown on 6H SiC substrates has been studied by atomic probe microscopy in air. Atomic-scale images of the 3C SiC surface have been obtained by STM which confirm the 111 line type orientation of the cubic 3C layer grown on the 0001 plane type surface of the hexagonal 6H substrate. The nearest-neighbor atomic spacing for the 3C layer has been measured to be 3.29 +/- 0.2 A, which is within 7 percent of the bulk value. Shallow terraces in the 3C layer have been observed by STM to separate regions of very smooth growth in the vicinity of the 3C nucleation point from considerably rougher 3C surface regions. These terraces are oriented at right angles to the growth direction. Atomic force microscopy has been used to study etch pits present on the 6H substrate due to high temperature HCl cleaning prior to CVD growth of the 3C layer. The etch pits have hexagonal symmetry and vary in depth from 50 nm to 1 micron.

  15. Enhancing the scopolamine production in transgenic plants of Atropa belladonna by overexpressing pmt and h6h genes.

    PubMed

    Wang, Xirong; Chen, Min; Yang, Chunxian; Liu, Xiaoqiang; Zhang, Lei; Lan, Xiaozhong; Tang, Kexuan; Liao, Zhihua

    2011-12-01

    Atropa belladonna is officially deemed as the commercial plant to produce scopolamine in China. In this study we report the simultaneous overexpression of two functional genes involved in biosynthesis of scopolamine, which encode the upstream key enzyme putrescine N-methyltransferase (PMT) and the downstream key enzyme hyoscyamine 6β-hydroxylase (H6H), respectively, in transgenic herbal plants Atropa belladonna. Analysis of gene expression profile indicated that both pmt and h6h were expressed at a higher level in transgenic lines, which would be favorable for biosynthesis of scopolamine. High-performance liquid chromatography result suggested that transgenic lines could produce higher accumulation of scopolamine at different levels compared with wild-type lines. Scopolamine content increased to 7.3-fold in transgenic line D9 compared with control lines. This study not only confirms that co-overexpression of pmt and h6h is an ideal method to improve the biosynthetic capacity of scopolamine but also successfully cultivates the transgenic line D9, which significantly enhanced the scopolamine accumulation. Our research can serve as an alternative choice to provide scopolamine resources for relative industry, which is more competitive than conventional market.

  16. [Study on optimal harvest period of Lonicera Flos (Lonicera macranthoides)].

    PubMed

    Li, Long-Yun; Zhang, Ying; Ma, Peng; Wu, Ye-Kuan

    2014-08-01

    To ascertain the optimal harvest period of Lonicera Flos (Lonicera macranthoides) the configuration yield and quality of L. macranthiodes bloom verity and bud verity flower at different develop periods were Observed. The quality of L. macranthiodes which harvested at different times of the day was Compared. The configuration was significant difference between different develop period of L. macranthiodes flower. As bud growth, yield increased. Bloom verity of L. macranthoides chlorogenic acid content was significantly lower after opening (silver flower stage, golden flower stage), before opening (young bud stage, green-white stage) have no significant difference of the quality. Bud verity of L. macranthoides macranthoidin B is significant lower at yellow-white stage, young bud stage and green-white stage have no significant difference of the quality. The chlorogenic acid and isochlorogenic acid A content is significant difference between L. macranthoides harvested at different time of the day. The optimal harvest period of bloom verity is the white stage, picking time for 10:00 before and after 18:00. The optimal harvest period is the green-white stage, picking time is 8:00 before and after 18:00.

  17. A first-principles study on the B{sub 5}O{sub 5}{sup +/0} and B{sub 5}O{sub 5}{sup −} clusters: The boron oxide analogs of C{sub 6}H{sub 5}{sup +/0} and CH{sub 3}Cl

    SciTech Connect

    Tian, Wen-Juan; You, Xue-Rui; Ou, Ting; Chen, Qiang; Li, Si-Dian; Li, Da-Zhi; Zhai, Hua-Jin

    2015-08-14

    The concept of boronyl (BO) and the BO/H isolobal analogy build an interesting structural link between boron oxide clusters and hydrocarbons. Based upon global-minimum searches and first-principles electronic structural calculations, we present here the perfectly planar C{sub 2v} B{sub 5}O{sub 5}{sup +} (1, {sup 1}A{sub 1}), C{sub 2v} B{sub 5}O{sub 5} (2, {sup 2}A{sub 1}), and tetrahedral C{sub s} B{sub 5}O{sub 5}{sup −} (3, {sup 1}A′) clusters, which are the global minima of the systems. Structural and molecular orbital analyses indicate that C{sub 2v} B{sub 5}O{sub 5}{sup +} (1) [B{sub 3}O{sub 3}(BO){sub 2}{sup +}] and C{sub 2v} B{sub 5}O{sub 5} (2) [B{sub 3}O{sub 3}(BO){sub 2}] feature an aromatic six-membered boroxol (B{sub 3}O{sub 3}) ring as the core with two equivalent boronyl terminals, similar to the recently reported boronyl boroxine D{sub 3h} B{sub 6}O{sub 6} [B{sub 3}O{sub 3}(BO){sub 3}]; whereas C{sub s} B{sub 5}O{sub 5}{sup −} (3) [B(BO){sub 3}(OBO){sup −}] is characterized with a tetrahedral B{sup −} center, terminated with three BO groups and one OBO unit, similar to the previously predicted boronyl methane T{sub d} B{sub 5}O{sub 4}{sup −} [B(BO){sub 4}{sup −}]. Alternatively, the 1–3 clusters can be viewed as the boron oxide analogs of phenyl cation C{sub 6}H{sub 5}{sup +}, phenyl radical C{sub 6}H{sub 5}, and chloromethane CH{sub 3}Cl, respectively. Chemical bonding analyses also reveal a dual three-center four-electron (3c-4e) π hyperbond in C{sub s} B{sub 5}O{sub 5}{sup −} (3). The infrared absorption spectra of B{sub 5}O{sub 5}{sup +} (1), B{sub 5}O{sub 5} (2), and B{sub 5}O{sub 5}{sup −} (3) and anion photoelectron spectrum of B{sub 5}O{sub 5}{sup −} (3) are predicted to facilitate their forthcoming experimental characterizations. The present work completes the B{sub n}O{sub n}{sup +/0/−} series for n = 1–6 and enriches the analogous relationship between boron oxides and hydrocarbons.

  18. Electrical properties and microstructural characterization of Ni/Ta contacts to n-type 6H-SiC

    NASA Astrophysics Data System (ADS)

    Zhou, Tian-Yu; Liu, Xue-Chao; Huang, Wei; Zhuo, Shi-Yi; Zheng, Yan-Qing; Shi, Er-Wei

    2015-12-01

    A Ni/Ta bilayer is deposited on n-type 6H-SiC and then annealed at different temperatures to form an ohmic contact. The electrical properties are characterized by I-V curve measurement and the specific contact resistance is extracted by the transmission line method. The phase formation and microstructure of the Ni/Ta bilayer are studied after thermal annealing. The crystalline and microstructure properties are analyzed by using glance incident x-ray diffraction (GIXRD), Raman spectroscopy, and transmission electron microscopy. It is found that the transformation from the Schottky to the Ohmic occurs at 1050 °C and the GIXRD results show a distinct phase change from Ta2C to TaC at this temperature. A specific contact resistance of 6.5× 10-5 Ω·cm2 is obtained for sample Ni(80 nm)/Ta(20 nm)/6H-SiC after being annealed at 1050 °C. The formation of the TaC phase is regarded as the main reason for the excellent Ohmic properties of the Ni/Ta contacts to 6H-SiC. Raman and TEM data reveal that the graphite carbon is drastically consumed by the Ta element, which can improve the contact thermal stability. A schematic diagram is proposed to illustrate the microstructural changes of Ni/Ta/6H-SiC when annealed at different temperatures. Project supported by the Innovation Program of the Chinese Academy of Sciences (Grant No. KJCX2-EW-W10), the Shanghai Rising-star Program, China (Grant No. 13QA1403800), the Industry-Academic Joint Technological Innovations Fund Project of Jiangsu Province, China (Grant No. BY2011119), and the National High-tech Research and Development Program of China (Grant Nos. 2013AA031603 and 2014AA032602).

  19. Damage Accumulation and Annealing in 6H-SiC Irradiated with Si+

    SciTech Connect

    Jiang, Weilin; Weber, William J.; Thevuthasan, Suntharampillai; McCready, David E.

    1998-10-01

    Damage accumulation and annealing in 6H-silicon carbide (alpha-SiC) single crystals have been studied in situ using 2.0 MeV HeRBS in a <0001>-axial channeling geometry (RBS/C). The damage was induced by 550 keV Si ion implantation (30 degrees off normal) at a temperature of -110 degrees C, and the damage recovery was investigated by subsequent isochromal annealing (20 min) over the temperature range from -110 degrees C to 900 degrees C. At ion fluences below 7.5 X 10 13 Si/cm (0.04 dpa in the damage peak), only point defects appear to be created. Furthermore, the defects on the Si sublattice can be completely recovered by thermal annealing at room temperature (RT), and recovery of defects on the C sublattice is suggested. At higher fluences of 6.6 x 10 15 Si/cm (-90 degrees C), an amorphous layer is created from the surface to a depth of 0.6 mu-m. Because of recovery processes at the buried crystalline-amorphous interface, the apparent thickness of this amorphous layer decreases slightly (<10%) with increasing temperature over the range from -90 degrees C to 600 degrees C.

  20. Electrical properties of unintentionally doped semi-insulating and conducting 6H-SiC

    NASA Astrophysics Data System (ADS)

    Mitchel, W. C.; Mitchell, W. D.; Fang, Z. Q.; Look, D. C.; Smith, S. R.; Smith, H. E.; Khlebnikov, Igor; Khlebnikov, Y. I.; Basceri, C.; Balkas, C.

    2006-08-01

    Temperature dependent Hall effect (TDH), low temperature photoluminescence (LTPL), secondary ion mass spectrometry (SIMS), optical admittance spectroscopy (OAS), and thermally stimulated current (TSC) measurements have been made on 6H-SiC grown by the physical vapor transport technique without intentional doping. n- and p-type as well semi-insulating samples were studied to explore the compensation mechanism in semi-insulating high purity SiC. Nitrogen and boron were found from TDH and SIMS measurements to be the dominant impurities that must be compensated to produce semi-insulating properties. The electrical activation energy of the semi-insulating sample determined from the dependence of the resistivity was 1.0eV. LTPL lines near 1.00 and 1.34eV, identified with the defects designated as UD-1 and UD-3, were observed in all three samples but the intensity of the UD-1 line was almost a factor of 10 more in the n-type sample than in the the p-type sample with that in the semi-insulating sample being intermediate between those two. OAS and TSC experiments confirmed the high purity of this material. The results suggest that the relative concentrations of a dominant deep level and nitrogen and boron impurities can explain the electrical properties in this material.

  1. A Fundamental Study of Heat Transfer Phenomenon in Periodic Structures

    DTIC Science & Technology

    2012-11-09

    household radiators or electric heaters, furnaces, combustion chambers, fires, rocket nozzles , power plants, engines etc. The importance of radiation...can be applied to any other problem related to the wave propagation through periodic structures such as acoustic wave and ultrasonic wave propagation

  2. Epitaxial growth of 6H silicon carbide in the temperature range 1320 C to 1390 C

    NASA Technical Reports Server (NTRS)

    Will, H. A.; Powell, J. A.

    1974-01-01

    High-quality epitaxial layers of 6H SiC have been grown on 6H SiC substrates with the grown direction perpendicular to the crystal c-axis. The growth was by chemical vapor deposition from methyltrichlorosilane (CH3SiCl3) in hydrogen at temperatures in the range of 1320 to 1390 C. Epitaxial layers up to 80 microns thick were grown at rates of 0.4 microns/min. Attempts at growth on the (0001) plane of 6H SiC substrates under similar conditions resulted in polycrystalline cubic SiC layers. Optical and X-ray diffraction techniques were used to characterize the grown layers.

  3. Monte Carlo Simulation of Electron Transport in 4H- and 6H-SiC

    SciTech Connect

    Sun, C. C.; You, A. H.; Wong, E. K.

    2010-07-07

    The Monte Carlo (MC) simulation of electron transport properties at high electric field region in 4H- and 6H-SiC are presented. This MC model includes two non-parabolic conduction bands. Based on the material parameters, the electron scattering rates included polar optical phonon scattering, optical phonon scattering and acoustic phonon scattering are evaluated. The electron drift velocity, energy and free flight time are simulated as a function of applied electric field at an impurity concentration of 1x10{sup 18} cm{sup 3} in room temperature. The simulated drift velocity with electric field dependencies is in a good agreement with experimental results found in literature. The saturation velocities for both polytypes are close, but the scattering rates are much more pronounced for 6H-SiC. Our simulation model clearly shows complete electron transport properties in 4H- and 6H-SiC.

  4. 6H-SiC Photoconductive Switches Triggered at Below Bandgap Wavelengths

    SciTech Connect

    Sullivan, J S; Stanley, J R

    2007-02-13

    Semi-insulating silicon carbide (SiC) is an attractive material for application as high voltage, photoconductive semiconductor switches (PCSS) due to its large bandgap, high critical electric field strength, high electron saturation velocity and high thermal conductivity. The critical field strength of 300 MV/m for 6H-SiC makes it particularly attractive for compact, high voltage, fast switching applications. To realize the benefits of the high bulk electric field strength of SiC and diffuse switch current, carriers must be excited throughout the bulk of the photo switch. Photoconducting switches with opposing electrodes were fabricated on ''a'' plane, vanadium compensated, semiinsulating, 6H-SiC substrates. The PCSS devices were switched by optically exciting deep extrinsic levels lying within the 6H-SiC bandgap. The SiC photoswitches were tested up to a bias voltage of 11000 V with a corresponding peak current of 150 A. The 6H-SiC substrates withstood average electric fields up to 27 MV/m. Minimum PCCS dynamic resistances of 2 and 10 {Omega} were obtained with 13 mJ optical pulses at 532 and 1064 nm wavelengths, respectively.

  5. Hidden Superlattice in Tl2(SC6H4S) and Tl2(SeC6H4Se) Solved from Powder X-ray Diffraction

    SciTech Connect

    K Stone; D Turner; M Singh; T Vaid; P Stephens

    2011-12-31

    The crystal structures of the isostructural title compounds poly[({mu}-benzene-1,4-dithiolato)dithallium], Tl{sub 2}(SC{sub 6}H{sub 4}S), and poly[({mu}-benzene-1,4-diselenolato)dithallium], Tl{sub 2}(SeC{sub 6}H{sub 4}Se), were solved by simulated annealing from high-resolution synchrotron X-ray powder diffraction. Rietveld refinements of an initial structure with one formula unit per triclinic cell gave satisfactory agreement with the data, but led to a structure with impossibly close non-bonded contacts. A disordered model was proposed to alleviate this problem, but an alternative supercell structure leads to slightly improved agreement with the data. The isostructural superlattice structures were confirmed for both compounds through additional data collection, with substantially better counting statistics, which revealed the presence of very weak superlattice peaks not previously seen. Overall, each structure contains Tl-S or Tl-Se two-dimensional networks, connected by phenylene bridges. The sulfur (or selenium) coordination sphere around each thallium is a highly distorted square pyramid or a 'see-saw' shape, depending upon how many Tl-S or Tl-Se interactions are considered to be bonds. In addition, the two compounds contain pairs of Tl{sup I} ions that interact through a closed-shell 'thallophilic' interaction: in the sulfur compound there are two inequivalent pairs of Tl atoms with Tl-Tl distances of 3.49 and 3.58 {angstrom}, while in the selenium compound those Tl-Tl interactions are at 3.54 and 3.63 {angstrom}.

  6. Periodic trends in bond dissociation energies. A theoretical study.

    PubMed

    Mó, Otilia; Yáñez, Manuel; Eckert-Maksić, Mirjana; Maksić, Zvonimir B; Alkorta, Ibón; Elguero, José

    2005-05-19

    Bond dissociation energies (BDEs) of all possible A-X single bonds involving the first- and second-row atoms, from Li to Cl, where the free valences are saturated by hydrogens, have been estimated through the use of the G3-theory and at the B3LYP/6-311+G(3df,2pd)//B3LYP/6-31G(2df,p) DFT level of theory. BDEs exhibit a periodical behavior. The A-X (A = Li, Be, B, Na, Mg, Al, and Si) BDEs show a steady increase along the first and the second row of the periodic table as a function of the atomic number Z(X). For A-X bonds involving electronegative atoms (A = C, N, O, F, P, S, and Cl) the bond energies achieve a maximum around Z(X) = 5. The same behavior is observed when BDEs are plotted against the electronegativity chi(X) of the atom X. Thus, for A-X bonds (A = Li, Be, B, Na, Mg, Al, Si), the BDEs for a fixed A increases, grosso modo, as the electronegativity differences between X and A increase, with some exceptions, which reflect the differences in the relaxation energies of the radicals produced upon the bond cleavage. A similar trend, albeit less pronounced, is found for single A-X bonds, where A = C, N, O, F, P, S, and Cl. However, there is an additional feature embodied in the enhancement of the strength of the A-boron bonds due to the ability of boron to act as a strong electron acceptor. The trends in bond lengths and charge densities at the bond critical points are in line with the aforementioned behavior.

  7. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    DOE PAGES

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; ...

    2016-01-16

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02–20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior.more » Moreover the 6H–SiC expanded isotropically. The magnitude of the swelling followed a ~0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ~7.8% volume expansion in SiC was observed prior to amorphization. Above ~0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. As a result, the as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.« less

  8. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    SciTech Connect

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; Terrani, Kurt A.; Specht, Eliot D.

    2016-01-16

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02–20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior. Moreover the 6H–SiC expanded isotropically. The magnitude of the swelling followed a ~0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ~7.8% volume expansion in SiC was observed prior to amorphization. Above ~0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. As a result, the as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.

  9. Deep level defects in sublimation-grown 6H silicon carbide investigated by DLTS and EPR

    NASA Astrophysics Data System (ADS)

    Irmscher, K.; Pintilie, I.; Pintilie, L.; Schulz, D.

    2001-12-01

    6H-SiC bulk single crystals grown by physical vapor transport (PVT) were investigated by deep-level transient spectroscopy (DLTS) and electron paramagnetic resonance (EPR). One of the observed deep level defects was identified as isolated tungsten on Si sites by EPR. The electron spin of {1}/{2} could be explained by W 5+ (5d 1). This is equivalent to the single positive charge state of a double donor when taking into account the Fermi level position in the n-type samples. The interpretation is also consistent with the DLTS detection of a W related deep level which showed a behavior of the capture of electrons and holes that hints at a double donor. In addition a tantalum related deep level is tentatively discussed. W and Ta were incorporated on electrically active sites in 6H-SiC only in low concentrations (2-4×10 14 cm -3) during crystal growth by PVT.

  10. Si6H12/Polymer Inks for Electrospinning a-Si Nanowire Lithium Ion Battery Anodes

    SciTech Connect

    Schulz, Douglas L.; Hoey, Justin; Smith, Jeremiah; Elangovan, Arumugasamy; Wu, Xiangfa; Akhatov, Iskander; Payne, Scott; Moore, Jayma; Boudjouk, Philip; Pederson, Larry; Xiao, Jie; Zhang, Jiguang

    2010-08-04

    Amorphous silicon nanowires 'a-SiNWs' have been prepared by electrospinning a liquid silane-based precursor. Cyclohexasilane 'Si6H12' was admixed with poly-methyl methacrylate (PMMA) in toluene giving an ink that was electrospun into the Si6H12/PPMA wires with diameters of 50-2000 nm. Raman spectroscopy revealed that thermal treatment at 350 C transforms this deposit into a-SiNWs. These materials were coated with a thin carbon layer and then tested as half-cells where a reasonable plateau in electrochemical cycling was observed after an initial capacity fade. Additionally, porous a-SiNWs were realized when the thermally decomposable binder polypropylene carbonate/polycyclohexene carbonate was used as the polymer carrier.

  11. Photoconductive and photovoltaic response of high-dark-resistivity 6H-SiC devices

    NASA Technical Reports Server (NTRS)

    Cho, Pak S.; Goldhar, Julius; Lee, Chi H.; Saddow, Stephen E.; Neudeck, Philip

    1995-01-01

    The optoelectronic properties of high-resistivity p-type hexagonal silicon carbide (6H-SiC) have been investigated using lateral photoconductive switches. Both photovoltaic and photoconductive effects are reported, measured at 337 nm, which is above the 6H-SiC absorption edge. These photoconductive switches have been fabricated with dark resistances of up to 1 M omega; photoconductive switching efficiencies of more than 80% have been achieved. In addition, these devices displayed a high-speed photovoltaic response to nanosecond laser excitations in the ultraviolet spectral region; in particular, the observed photovoltaic response pulse width can be shorter than the exciting laser pulse width. This subnanosecond photovoltaic response has been modeled and good qualitative agreement with experiment has been obtained.

  12. Inelastic rate coefficients for collisions of C6H- with H2 and He

    NASA Astrophysics Data System (ADS)

    Walker, Kyle M.; Lique, François; Dumouchel, Fabien; Dawes, Richard

    2017-04-01

    The recent detection of anions in the interstellar medium has shown that they exist in a variety of astrophysical environments - circumstellar envelopes, cold dense molecular clouds and star-forming regions. Both radiative and collisional processes contribute to molecular excitation and de-excitation in these regions so that the 'local thermodynamic equilibrium' approximation, where collisions cause the gas to behave thermally, is not generally valid. Therefore, along with radiative coefficients, collisional excitation rate coefficients are needed to accurately model the anionic emission from these environments. We focus on the calculation of state-to-state rate coefficients of the C6H- molecule in its ground vibrational state in collisions with para-H2, ortho-H2 and He using new potential energy surfaces. Dynamical calculations for the pure rotational excitation of C6H- were performed for the first 11 rotational levels (up to j1 = 10) using the close-coupling method, while the coupled-states approximation was used to extend the H2 rate coefficients to j1 = 30, where j1 is the angular momentum quantum number of C6H-. State-to-state rate coefficients were obtained for temperatures ranging from 2 to 100 K. The rate coefficients for H2 collisions for Δj1 = -1 transitions are of the order of 10-10 cm3 s-1, a factor of 2 to 3 greater than those of He. Propensity rules are discussed. The collisional excitation rate coefficients produced here impact astrophysical modelling since they are required for obtaining accurate C6H- level populations and line emission for regions that contain anions.

  13. The metastable HCl · 6H2O phase - IR spectroscopy, phase transitions and kinetic/thermodynamic properties in the range 170-205 K

    NASA Astrophysics Data System (ADS)

    Chiesa, S.; Rossi, M. J.

    2013-07-01

    In this laboratory study, 1 to 2 μm thick polycrystalline ice films have been grown under stirred flow reactor (SFR) conditions and subsequently doped with metered amounts of HCl under static conditions. A multidiagnostic approach including FTIR absorption spectroscopy in transmission, residual gas mass spectrometry (MS) and total pressure measurement was employed. Depending on the growth protocol controlling both temperature and partial pressure of HCl (PHCl), either amorphous HCl/H2O or crystalline HCl hexahydrate (HCl · 6H2O) have been obtained. After controlled doping with HCl and evaporation of excess H2O from the ice film, transmission FTIR of pure HCl · 6H2O films and use of calibrated residual gas MS enabled the measurement of differential (peak) IR cross sections at several mid-IR frequencies (σ = (6.5 ± 1.9) × 10-19 cm2 molec-1 at 1635 cm-1 as an example). Two types of kinetic experiments on pure HCl · 6H2O have been performed under SFR conditions: (a) evaporation of HCl · 6H2O under H2O-poor conditions over a narrow T range, and (b) observation of the phase transition from crystalline HCl · 6H2O to amorphous HCl/H2O under H2O-rich conditions at increasing T. The temperature dependence of the zero-order evaporation flux of HCl in pure HCl · 6H2O monitored at 3426 cm-1 led to log(Jev) molec cm-2s-1= (36.34 ± 3.20) - (80 810 ± 5800)/2.303RT with R=8.312 JK-1 mol-1. HCl · 6H2O has a significant intrinsic kinetic barrier to HCl evaporation of 15.1 kJ mol-1 in excess of the HCl sublimation enthalpy of 65.8 kJ mol-1 at 200 K but is kinetically unstable (metastable) at typical UT/LS conditions of HCl partial pressure (P(HCl)) and temperature. Water-rich HCl · 6H2O undergoes a facile phase transition from crystalline to the amorphous/ supercooled/disordered state easily observable at T≥ 195 K under both static and SFR conditions. This corresponds to low P(HCl) in the neighborhood of 10-7 Torr that also prevails at the Upper Troposphere

  14. The low frequency dynamics of supercooled LiBr, 6H2O.

    PubMed

    Bove, L; Dreyfus, C; Polian, A; Bonello, B; Malfanti, I; Taschin, A; Torre, R; Pick, R M

    2011-01-21

    We present results of a series of experiments performed on LiBr, 6H(2)0 from room temperature down to 172 K ≈ 1.2T(g). These ultrasound, Brillouin and depolarized light scattering, and transient grating experiments show that, above 215 K, this solution behaves like supercooled water: its zero frequency sound velocity C(0) continuously decreases with decreasing temperature, and the reorientational dynamics of the water molecules can be directly detected at some temperatures of this domain. Conversely, below 215 K, a new regime sets in, where the apparent C(0) is practically temperature independent and where a β, Arrenhius like, relaxation process coexists with the usual, Vogel-Fulcher like, α relaxation process of the supercooled liquid. These results are similar to those recently obtained in LiCl, 6H(2)O. The onset of the new regime is possibly due to an increase of the interaction of the water molecules with a neighboring Li(+) ion when lowering the temperature. We also compare our results with published dielectric data on water solutions of glass forming polyalcohols. Some of them present a low temperature splitting of their relaxation time similar to what is found in LiBr, 6H(2)O.

  15. 13-week inhalation toxicity study (including 6- and 13-week recovery periods) with ammonium persulfate dust in albino rats.

    PubMed

    Signorin, J; Ulrich, C E; Butt, M T; D'Amato, E A

    2001-11-01

    The subchronic inhalation toxicity of ammonium persulfate was characterized using Sprague-Dawley rats (20/sex/group) at respirable dust concentrations of 0, 5.0, 10.3, and 25 mg/m(3). Whole-body exposures were conducted 6 h/day, 5 days/wk for 13 wk. Gravimetric airborne test material samples were taken daily and particle size samples were taken weekly from each exposure chamber for analysis. Ten animals/sex/group were necropsied after 13 wk of exposure, and 5 animals/sex/group were held for 6- and 13-wk recovery periods. Animals were observed for clinical signs. Effects on body weight, food consumption, clinical chemistry and hematology, ophthalmologic parameters, organ weights, gross lesions, and histopathology were evaluated. There were no exposure-related deaths during the study. Rales and increased respiration rate were noted in both males and females in the 25 mg/m(3) group, and in a few animals in the 10.3 mg/m(3) group. The incidence of these clinical signs decreased to zero during the first few weeks of the recovery period. Body weights for both males and females in the 25 mg/m(3) group were significantly depressed during most of the exposure period compared to the control group. By the end of the recovery period, body weights for the exposed animals were similar to the control group values. Lung weights were elevated in the 25 mg/m(3) group after 13 wk of exposure, but were similar to controls at 6 wk postexposure. Irritation of the trachea and bronchi/bronchiole was noted microscopically after 13 wk of exposure to 25 mg/m(3). These lesions had recovered by 6 wk postexposure. Based on the results of this study, the no-observed-adverse-effect level (NOAEL) was 10.3 mg/m(3), while the no-observed-effect level (NOEL) for exposure of rats to a dust aerosol of ammonium persulfate was 5.0 mg/m(3).

  16. A study of lightning flashes attending periods of banded snowfall

    NASA Astrophysics Data System (ADS)

    Market, Patrick S.; Becker, Amy E.

    2009-01-01

    Lightning flashes (N = 1088) associated with 24 thundersnow events in the central United States were analyzed to document flash polarity, signal strength, and multiplicity. Negative lightning flashes (N = 872; 80%) dominated positive flashes (N = 216; 20%) with wintry precipitation in this study, which stands in contrast to the majority of the research done on winter thunderstorms (primarily in Japan). Otherwise, limited work has been done, although thundersnow has been documented in the mid-latitudes of North America, Europe and Asia. Statistics on peak amplitude were determined for negative (positive) flashes, yielding mean and standard deviation values of -24 kA +/- 22 kA (+38 kA +/- 34 kA). A subset of winter lightning events (N = 16) were then sought that occurred with banded (single or multiple) snowfall, as banding often denotes greater organization in the atmosphere (e.g., a jet streak aloft to aid in ascent, or a low level jet streak to aid with moisture and thermal transport) and thus the potential for deeper snow totals. Radar reflectivity values were recorded at the location of each lightning flash, as well as the maximum radar reflectivity within the associated snow band. The location of the lightning activity within the snow band was also noted as being either leading edge (LE), trailing edge (TE), core (C), or not correlated (NC), with respect to the motion of the parent band. The majority of lightning flashes were found downstream of areas of highest radar reflectivity with respect to the motion of the snow bands, and not with the highest reflectivity values. If one uses the highest reflectivity values in a snowband as a proxy for the greatest surface snowfall intensity, then the ground terminus of a cloud-to-ground lightning (CG) flash is often not co-located with the heaviest snowfall rates. However, the work completed here does place the location of the typical CG flash ~15 km downstream of the snowband location, so one could use the occurrence

  17. Rationalization of Periodical Holdings: A Case Study at Chalmers University Library.

    ERIC Educational Resources Information Center

    Fjallbrant, Nancy

    1984-01-01

    Describes study of periodical use in medium-sized university of technology which examined use of individual periodicals in relation to language of publication; patterns of use for interlibrary lending and for multiple copy journals; methods and costs for acquiring infrequently used periodicals. Thirty-three references and most frequently used…

  18. 6H-SiC Transistor Integrated Circuits Demonstrating Prolonged Operation at 500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Spry, David J.; Chen, Liang-Yu; Chang, Carl W.; Beheim, Glenn M.; Okojie, Robert S.; Evans, Laura J.; Meredith, Roger; Ferrier, Terry; Krasowski, Michael J.; Prokop, Norman F.

    2008-01-01

    The NASA Glenn Research Center is developing very high temperature semiconductor integrated circuits (ICs) for use in the hot sections of aircraft engines and for Venus exploration where ambient temperatures are well above the approximately 300 degrees Centigrade effective limit of silicon-on-insulator IC technology. In order for beneficial technology insertion to occur, such transistor ICs must be capable of prolonged operation in such harsh environments. This paper reports on the fabrication and long-term 500 degrees Centigrade operation of 6H-SiC integrated circuits based on epitaxial 6H-SiC junction field effect transistors (JFETs). Simple analog amplifier and digital logic gate ICs have now demonstrated thousands of hours of continuous 500 degrees Centigrade operation in oxidizing air atmosphere with minimal changes in relevant electrical parameters. Electrical characterization and modeling of transistors and circuits at temperatures from 24 degrees Centigrade to 500 degrees Centigrade is also described. Desired analog and digital IC functionality spanning this temperature range was demonstrated without changing the input signals or power supply voltages.

  19. High temperature ohmic and Schottky contacts to N-type 6H-SiC nickel

    NASA Astrophysics Data System (ADS)

    Williams, John R.; Bozack, Michael J.; Isaacs-Smith, Tamara; Luckowski, Eric D.; Meadows, Christopher; Crofton, John; McMullin, Paul G.

    1995-01-01

    We report specific contact resistances measured at elevated temperatures for Ni ohmic contacts to 6H-SiC. The specific contact resistances were measured with the linear transmission line method at both room temperature and at 773 K and yielded values <5×10-6 Ω-cm2 at both temperatures. The trend shows a decreasing contact resistance at higher temperatures. The annealed metal film is a nickel silicide with substantial mixing of C throughout the silicide layer. Also reported are the results of I-V and C-V barrier height measurements for Ni Schottky contacts to 6H-SiC. Current-voltage barrier heights as high as 1.2 eV have been measured, and the contacts show good electrical and physical stability following long-term anneals at 573 K in a vacuum ambient of 10-6 torr. These ohmic and Schottky contacts have been developed by the CCDS in collaboration with the Air Force and the Westinghouse Electric Corporation, and transfer of our contact technology to the Westinghouse Science and Technology is now complete.

  20. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6-oxide. 721.5560 Section 721... Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6... identified as formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with...

  1. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6-oxide. 721.5560 Section 721... Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6... identified as formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with...

  2. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6-oxide. 721.5560 Section 721... Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6... identified as formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with...

  3. Utilization of critical periods during development to study the effects of low levels of environmental agents

    SciTech Connect

    Russell, L. B.

    1980-01-01

    Careful definition of critical periods in the development of selected characters can result in experimental systems that may be highly useful in studying risk at low levels of exposure. Three examples are presented. Epidemiological investigations can lose much of their value unless critical periods are known for the end points being studied.

  4. The investigation of cobalt intercalation underneath epitaxial graphene on 6H-SiC(0 0 0 1)

    NASA Astrophysics Data System (ADS)

    Zhang, Yuxi; Zhang, Hanjie; Cai, Yiliang; Song, Junjie; He, Pimo

    2017-02-01

    The intercalation behaviour of cobalt underneath both epitaxial graphene monolayer and bilayer on 6H-SiC(0001) have been investigated by scanning tunneling microscopy (STM) and density functional theory (DFT). Upon deposition, cobalt atoms prefer to agglomerate into clusters on the epitaxial graphene. After annealing the sample to 850 °C, the intercalation of the adsorbed cobalt atoms into both monolayer and bilayer epitaxial graphene on SiC takes place, as observed by the atomically resolved STM images. Further studies based on DFT modeling and simulated STM images show that, resulting from the interplay between the intercalated cobalt atoms and the carbon layers sandwiching it, the most energetically favourable intercalation sites of cobalt atoms underneath monolayer and bilayer graphene differ. Furthermore, the results show energy barriers of 0.60 eV and 0.41 eV for cobalt penetration through mono-vacancy defects at monolayer and bilayer graphene.

  5. Solvent effects on infrared spectra of progesterone in CHCl 3/ cyclo-C 6H 12 binary solvent systems

    NASA Astrophysics Data System (ADS)

    Liu, Qing; Wang, Xiao-yan; Zhang, Hui

    2007-01-01

    The infrared spectroscopy studies of the C 3 and C 20 carbonyl stretching vibrations ( υ(C dbnd O)) of progesterone in CHCl 3/ cyclo-C 6H 12 binary solvent systems were undertaken to investigate the solute-solvent interactions. With the mole fraction of CHC1 3 in the binary solvent mixtures increase, three types of C 3 and C 20 carbonyl stretching vibration band of progesterone are observed, respectively. The assignments of υ(C dbnd O) of progesterone are discussed in detail. In the CHCl 3-rich binary solvent systems or pure CHCl 3 solvent, two kinds of solute-solvent hydrogen bonding interactions coexist for C 20 C dbnd O. Comparisons are drawn for the solvent sensitivities of υ(C dbnd O) for acetophenone and 5α-androstan-3,17-dione, respectively.

  6. Thermochemistry and reaction paths in the oxidation reaction of benzoyl radical: C6H5C•(═O).

    PubMed

    Sebbar, Nadia; Bozzelli, Joseph W; Bockhorn, Henning

    2011-10-27

    Alkyl substituted aromatics are present in fuels and in the environment because they are major intermediates in the oxidation or combustion of gasoline, jet, and other engine fuels. The major reaction pathways for oxidation of this class of molecules is through loss of a benzyl hydrogen atom on the alkyl group via abstraction reactions. One of the major intermediates in the combustion and atmospheric oxidation of the benzyl radicals is benzaldehyde, which rapidly loses the weakly bound aldehydic hydrogen to form a resonance stabilized benzoyl radical (C6H5C(•)═O). A detailed study of the thermochemistry of intermediates and the oxidation reaction paths of the benzoyl radical with dioxygen is presented in this study. Structures and enthalpies of formation for important stable species, intermediate radicals, and transition state structures resulting from the benzoyl radical +O2 association reaction are reported along with reaction paths and barriers. Enthalpies, ΔfH298(0), are calculated using ab initio (G3MP2B3) and density functional (DFT at B3LYP/6-311G(d,p)) calculations, group additivity (GA), and literature data. Bond energies on the benzoyl and benzoyl-peroxy systems are also reported and compared to hydrocarbon systems. The reaction of benzoyl with O2 has a number of low energy reaction channels that are not currently considered in either atmospheric chemistry or combustion models. The reaction paths include exothermic, chain branching reactions to a number of unsaturated oxygenated hydrocarbon intermediates along with formation of CO2. The initial reaction of the C6H5C(•)═O radical with O2 forms a chemically activated benzoyl peroxy radical with 37 kcal mol(-1) internal energy; this is significantly more energy than the 21 kcal mol(-1) involved in the benzyl or allyl + O2 systems. This deeper well results in a number of chemical activation reaction paths, leading to highly exothermic reactions to phenoxy radical + CO2 products.

  7. A use study of speech pathology and audiology periodicals at Illinois State University.

    PubMed

    Duran, N; Buckley, C E; Ng, M L

    1997-10-01

    No core list of periodicals exists for speech pathology and audiology. Faced with the prospect of having to cancer periodicals for all subjects, the science librarians at Illinois State University decided to determine which science periodicals were used most heavily. A one-year study of science periodical reshelving and interlibrary loan requests yielded ranked lists of periodicals important to speech pathology and audiology faculty and students at Illinois State University. The three most heavily used journals were the Journal of Speech and Hearing Research, ASHA, and Topics in Language Disorders. Most of the periodicals on the lists were indexed by either MEDLINE or UnCover, or by both. While the lists of journals developed in the study are not sufficient to serve as true core lists, they should be useful to libraries supporting comparable programs in speech pathology and audiology.

  8. Room-temperature ferromagnetism in Cu-implanted 6H-SiC single crystal

    NASA Astrophysics Data System (ADS)

    Zheng, H. W.; Yan, Y. L.; Lv, Z. C.; Yang, S. W.; Li, X. G.; Liu, J. D.; Ye, B. J.; Peng, C. X.; Diao, C. L.; Zhang, W. F.

    2013-04-01

    200 keV Cu+ ions were implanted into 6H-SiC single crystal at room temperature with fluence of 8 × 1015 cm-2. No ferromagnetism (FM)-related secondary phase was found by the results of high-resolution x-ray diffraction and x-ray photoelectron spectroscopy. Positron annihilation lifetime spectroscopy results indicated that the main defect type was silicon vacancy and the concentration of it increased after Cu implantation. The room-temperature ferromagnetism was detected by superconducting quantum interference device. First-principles calculations revealed that the magnetic moments mainly come from the 2p orbitals of C atoms and 3d orbitals of Cu dopant. The origin of the FM has been discussed in detail.

  9. Periodic variation in the geomagnetic activity - A study based on the Ap index

    NASA Technical Reports Server (NTRS)

    De Gonzalez, Alicia L. C.; Gonzalez, Walter D.; Dutra, Severino L. G.; Tsurutani, Bruce T.

    1993-01-01

    The monthly and daily samples of the Ap index for the interval from 1932 through 1982 were studied using the power spectrum technique. Results obtained for Bartel's period (about 27 days), the semiannual period, the dual-peak solar cycle distribution of geomagnetic storms, and certain other medium-scale periodicities are examined in detail. In addition, results on the cumulative occurrence number of storms per decade as a function of the Ap and Dst indices for the storm are presented.

  10. A Study of the Orbital Periods of Deeply Eclipsing SW Sextantis Stars

    NASA Astrophysics Data System (ADS)

    Boyd, D.

    2012-06-01

    Results are presented of a five-year project to study the orbital periods of eighteen deeply eclipsing novalike cataclysmic variables, collectively known as SW Sextantis stars, by combining new measurements of eclipse times with published measurements stretching back in some cases over fifty years. While the behavior of many of these binary systems is consistent with a constant orbital period, it is evident that in several cases this is not true. Although the time span of these observations is relatively short, evidence is emerging that the orbital periods of some of these stars show cyclical variation with periods in the range 10-40 years. The two stars with the longest orbital periods, V363 Aur and BT Mon, also show secular period reduction with rates of -6.6 x 10-8 days/year and -3.3 x 10-8 days/year. New ephemerides are provided for all eighteen stars to facilitate observation of future eclipses.

  11. The effect of glycerol on properties of chitosan/poly(vinyl alcohol) films with AlCl3·6H2O aqueous solution as the solvent for chitosan.

    PubMed

    Jiang, Xiancai; Zhao, Yulai; Hou, Linxi

    2016-01-01

    The AlCl3·6H2O aqueous solution was used to dissolve chitosan (CS) and the CS/poly(vinyl alcohol) (PVA) blend films were prepared at the absence of acetic acid. AlCl3·6H2O was retained in CS/PVA film and glycerol was added to form the complex plasticizer with AlCl3·6H2O. The effect of glycerol on the water sorption, crystalline, thermal and mechanical properties of AlCl3·6H2O doped CS/PVA film was studied by atomic force microscopy, X-ray diffraction, thermal gravity analysis and tensile testing, respectively. The experimental results showed that glycerol had a significant positive effect on the properties of AlCl3·6H2O doped CS/PVA films. With the synergism effect of AlCl3·6H2O and glycerol, the prepared CS/PVA films showed excellent mechanical properties. With the addition of 30wt% glycerol, the AlCl3·6H2O doped CS/PVA films behave the tensile strength of 39MPa and elongation at break of 120%, respectively.

  12. Long-Term Characterization of 6H-SiC Transistor Integrated Circuit Technology Operating at 500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Spry, David J.; Chen, Liang-Yu; Chang, Carl W.; Beheim, Glenn M.; Okojie, Robert S.; Evans, Laura J.; Meredith Roger D.; Ferrier, Terry L.; Krasowski, Michael J.; Prokop, Norman F.

    2008-01-01

    NASA has been developing very high temperature semiconductor integrated circuits for use in the hot sections of aircraft engines and for Venus exploration. This paper reports on long-term 500 C electrical operation of prototype 6H-SiC integrated circuits based on epitaxial 6H-SiC junction field effect transistors (JFETs). As of this writing, some devices have surpassed 4000 hours of continuous 500 C electrical operation in oxidizing air atmosphere with minimal change in relevant electrical parameters.

  13. Are Seminar Periods Supportive of the Professional Development of Social Studies Teachers?

    ERIC Educational Resources Information Center

    Demir, Selçuk Besir; Dogan, Soner; Atasoy, Turgay

    2016-01-01

    The purpose of this study is to determine the efficiency of the seminar periods intended for contributing to the professional development of social studies teachers based on their own perspectives. This study adopts a qualitative approach and is carried out in the form of a case study. Among the purposeful sampling methods, the criteria sample…

  14. Sodium dipotassium citrate, NaK2C6H5O7

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2016-01-01

    The crystal structure of sodium dipotassium citrate, Na+·2K+·C6H5O7 3−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The Na+ and one of the K+ cations are six-coordinate, with bond-valence sums of 1.13 and 0.92 valence units, respectively, while another crystallographically independent K+ cation is seven-coordinate with a bond-valence sum of 1.20. The [KO6] and [KO7] polyhedra share edges and corners to form layers perpendicular to the b axis. The distorted [NaO6] octa­hedra share edges to form chains along the a axis. The result is a three-dimensional network. The only O—H⋯O hydrogen bond is an intra­molecular one between the hy­droxy group and a terminal carboxyl­ate group. PMID:27006817

  15. Quantum confinement effect in 6H-SiC quantum dots observed via plasmon-exciton coupling-induced defect-luminescence quenching

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoxiao; Zhang, Yumeng; Fan, Baolu; Fan, Jiyang

    2017-03-01

    The quantum confinement effect is one of the crucial physical effects that discriminate a quantum material from its bulk material. It remains a mystery why the 6H-SiC quantum dots (QDs) do not exhibit an obvious quantum confinement effect. We study the photoluminescence of the coupled colloidal system of SiC QDs and Ag nanoparticles. The experimental result in conjunction with the theoretical calculation reveals that there is strong coupling between the localized electron-hole pair in the SiC QD and the localized surface plasmon in the Ag nanoparticle. It results in resonance energy transfer between them and resultant quenching of the blue surface-defect luminescence of the SiC QDs, leading to uncovering of a hidden near-UV emission band. This study shows that this emission band originates from the interband transition of the 6H-SiC QDs and it exhibits a remarkable quantum confinement effect.

  16. Emotional anticipation after delivery - a longitudinal neuroimaging study of the postpartum period.

    PubMed

    Gingnell, Malin; Toffoletto, Simone; Wikström, Johan; Engman, Jonas; Bannbers, Elin; Comasco, Erika; Sundström-Poromaa, Inger

    2017-12-01

    Neuroimaging research has begun to unveil the mechanisms behind emotion processing during the postpartum period, which, in turn, may be of relevance for the development of postpartum depression. The present study sought to longitudinally investigate the neural correlates of emotion anticipation during the postpartum period in healthy women. Functional magnetic resonance imaging was employed to measure the blood oxygen level-dependent signal in the brain in response to anticipation of negative emotional stimuli and during processing of images with positive or negative valence. The participating women were scanned twice: the first scan occurred during the first 48 hours after delivery, and the second was performed 4-6 weeks after delivery. The early postpartum period was characterized by higher anterior cingulate cortex reactivity during anticipation of negative emotional stimuli than the late postpartum period. This was accompanied by a negative relationship with insular reactivity during the early postpartum period and a trend towards an increase in insular reactivity in the late postpartum period. Thus, during the first four weeks of the postpartum period, a diminished top-down regulatory feedback on emotion-related areas of the brain was noted. This finding suggests a physiologically important adaptation during the healthy postpartum period.

  17. Synthesis, structural characterization and biological activity of fluorinated Schiff-bases of the type [C6H4-1-(OH)-3-(CHdbnd NArF)

    NASA Astrophysics Data System (ADS)

    Avila-Sorrosa, Alcives; Hernández-González, Jorge Ignacio; Reyes-Arellano, Alicia; Toscano, Rubén A.; Reyes-Martínez, Reyna; Roberto Pioquinto-Mendoza, J.; Morales-Morales, David

    2015-04-01

    A series of fluorinated imines of the type [C6H4-1-(OH)-3-(CHdbnd NArF)]; ArFdbnd C6H4-4-F (1), C6H3-2,3-F2 (2), C6H3-3,5-F2 (3), C6H2-2,4,6-F3 (4), C6H4-3-CF3 (5), C6H3-3,5-(CF3)2 (6), were synthesized and fully characterized including single crystal X-ray diffraction analyses of compounds [C6H4-1-(OH)-3-(CHdbnd NC6H4-4-F)] (1), [C6H4-1-(OH)-3-(CHdbnd NC6H3-3,5-F2)] (3), [C6H4-1-(OH)-3-(CHdbnd NC6H4-3-CF3)] (5). Further analyses of these results allowed the identification of the predominant non-covalent interactions and supramolecular arrangements in the solid state. Exploration of the anti-bacterial activity against both gram-positive and gram-negative bacteria showed those compounds including F or CF3 substituents at the meta positions i.e. [C6H4-1-(OH)-3-(CHdbnd NC6H3-3,5-F2)] (3), [C6H4-1-(OH)-3-(CHdbnd NC6H4-3-CF3)] (5), [C6H4-1-(OH)-3-(CHdbnd NC6H3-3,5-(CF3)2)] (6), to be the best when their activity is compared versus ampicillin.

  18. Competitive solvation of K+ by C6H6 and H2O in the K+-(C6H6)n-(H2O)m (n = 1-4; m = 1-6) aggregates

    NASA Astrophysics Data System (ADS)

    Albertí, Margarita; Lago, Noelia Faginas

    2013-04-01

    The competitive solvation of the potassium ion by benzene and water is investigated at molecular level by means of Molecular Dynamics simulations on the K+-(C6H6) n -(H2O) m ( n = 1-4; m = 1-6) ionic aggregates. The preference of K+ to bind C6H6 or H2O is investigated in the range of temperatures in which isomerisation processes are likely by adding water and benzene to the K+-(C6H6) n and K+-(H2O) m aggregates, respectively. Hydrogen bonds and the π-hydrogen bond, in spite of their weakness with respect to the K+- π and K+-H2O interactions, play an important role in stabilising different isomers, thus favouring isomerisation processes. Accordingly with experimental information it has been found that K+ bind preferably C6H6 rather than H2O and that the fragmentation of C6H6 is only observed for aggregates containing four molecules of benzene.

  19. Optimal recall period for caregiver-reported illness in risk factor and intervention studies: a multicountry study.

    PubMed

    Arnold, Benjamin F; Galiani, Sebastian; Ram, Pavani K; Hubbard, Alan E; Briceño, Bertha; Gertler, Paul J; Colford, John M

    2013-02-15

    Many community-based studies of acute child illness rely on cases reported by caregivers. In prior investigations, researchers noted a reporting bias when longer illness recall periods were used. The use of recall periods longer than 2-3 days has been discouraged to minimize this reporting bias. In the present study, we sought to determine the optimal recall period for illness measurement when accounting for both bias and variance. Using data from 12,191 children less than 24 months of age collected in 2008-2009 from Himachal Pradesh in India, Madhya Pradesh in India, Indonesia, Peru, and Senegal, we calculated bias, variance, and mean squared error for estimates of the prevalence ratio between groups defined by anemia, stunting, and underweight status to identify optimal recall periods for caregiver-reported diarrhea, cough, and fever. There was little bias in the prevalence ratio when a 7-day recall period was used (<10% in 35 of 45 scenarios), and the mean squared error was usually minimized with recall periods of 6 or more days. Shortening the recall period from 7 days to 2 days required sample-size increases of 52%-92% for diarrhea, 47%-61% for cough, and 102%-206% for fever. In contrast to the current practice of using 2-day recall periods, this work suggests that studies should measure caregiver-reported illness with a 7-day recall period.

  20. The Wannier-Stark effects in the 6H-SiC planar junction field-effect transistors with a p-n junction as the gate

    SciTech Connect

    Sankin, V. I. Shkrebii, P. P.; Lebedev, A. A.

    2006-10-15

    Dependence of the short-circuit photocurrent on the voltage V{sub g} applied to the gate of the 6H-SiC planar field-effect transistor is studied. The negative differential photoconductivity appeared at a certain value of V{sub g}; the parameters of this photoconductivity corresponded to those of the Wannier-Stark ladders in the natural 6H-SiC super lattice. At the same value of V{sub g}, a fairly abrupt decrease to zero of the source-drain current I{sub sd} is observed, which is indicative of cutoff at the voltage that is much lower than the expected cutoff voltage for this structure. The effect is attributed to a decrease in mobility in the mode of the Wannier-Stark ladders, a decrease in the rate of ionization of the donor atoms, and a reduction in the screening of the field.

  1. Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. Part VI: FT-IR spectra of isomorphously isolated species. NH4+ ions isolated in MKPO 4·6H 2O (M = Mg; Ni) and PO43- ions isolated in MgNH 4AsO 4·6H 2O

    NASA Astrophysics Data System (ADS)

    Cahil, A.; Šoptrajanov, B.; Najdoski, M.; Lutz, H. D.; Engelen, B.; Stefov, V.

    2008-03-01

    Examination of mixed crystals, especially those with isomorphously isolated ions, has proved very useful in spectra-structure correlation studies. Room (RT) and low temperature (LNT) FT-IR spectra of ammonium doped in MgKPO 4·6H 2O and NiKPO 4·6H 2O and phosphate doped in MgNH 4AsO 4·6H 2O in different degrees were recorded. All three compounds are isostructural with struvite, MgNH 4PO 4·6H 2O, space group Pmn2 1, forming substitutional mixed crystals with Cs symmetry of the anions. Analysis of the region of ν 4(NH 4), ν 3(PO 4) and ν 4(PO 4) modes of LNT FT-IR difference spectra of analogues with a small content of NH4+ and PO43- revealed the expected decrease of Td symmetry of free NH4+ and PO43- ions to Cs site symmetry. Due to the Cs site symmetry of the anions, the degeneration of the ν 4(NH 4), ν 3PO 4) and ν 4PO 4) modes is raised and, hence, three components are observed in the difference FT-IR spectra. This conclusion can not be derived only from studies of no-doped polycrystalline samples of struvite type compounds.

  2. Pharmacologic Evaluation of Antidepressant Activity and Synthesis of 2-Morpholino-5-phenyl-6H-1,3,4-thiadiazine Hydrobromide

    PubMed Central

    Sarapultsev, Alexey P.; Chupakhin, Oleg N.; Sarapultsev, Petr A.; Sidorova, Larisa P.; Tseitler, Tatiana A.

    2016-01-01

    Substituted thiadiazines exert a reliable therapeutic effect in treating stress, and a schematic description of their ability to influence all aspects of a stress response has been depicted. This study was conducted to pharmacologically evaluate compound L-17, a substituted thiadiazine, (2-morpholino-5-phenyl-6H-1,3,4-thiadiazine, hydrobromide) for possible anti-psychotic/antidepressant activity. Compound L-17 was synthesized by cyclocondensation of α-bromoacetophenone with the original morpholine-4-carbothionic acid hydrazide. Pharmacologic evaluations were conducted using methods described by E.F. Lavretskaya (1985), and in accordance with published guidelines for studying drugs for neuroleptic activity. Compound L-17 was evaluated for various possible mechanisms of action, including its effects on cholinergic system agonists/antagonists, dopaminergic neurotransmission, the adrenergic system, and 5-HT3 serotonin receptors. One or more of these mechanisms may be responsible for the beneficial effects shown by thiadiazine compounds in experiments conducted to evaluate their activity in models of acute stress and acute myocardial infarction. PMID:27213404

  3. Study of periodic motions of a satellite with a magnetic damper

    NASA Technical Reports Server (NTRS)

    Sadov, Y. A.; Teterin, A. D.

    1979-01-01

    The motion of a satellite with a magnetic damper in the plane of a circular polar orbit is studied. The asymptotics of periodic solutions are constructed for a satellite close to axisymmetric and the radius of convergence is evaluated for the power series obtained. In a broad range of values of parameters, a periodic solution is obtained by numerical integration of equations of motion of the satellite. The asymptotics of a bifurcated curve obtained (the curve on which origin of a pair of periodic solutions occurs) in the space of the parameters agrees well with the results of numerical computation with all physical values of these parameters. A breakdown is made of the space of the initial data of phase variables in the field of effect of different types of periodic motion.

  4. Incubation period and immune function: a comparative field study among coexisting birds.

    PubMed

    Palacios, Maria G; Martin, Thomas E

    2006-01-01

    Developmental periods are integral components of life history strategies that can have important fitness consequences and vary enormously among organisms. However, the selection pressures and mechanisms causing variation in length of developmental periods are poorly understood. Particularly puzzling are prolonged developmental periods, because their selective advantage is unclear. Here we tested the hypotheses that immune function is stronger in species that are attacked at a higher rate by parasites and that prolonged embryonic development allows the development of this stronger immune system. Through a comparative field study among 12 coexisting passerine bird species, we show that species with higher blood parasite prevalence mounted stronger cellular immune responses than species with lower prevalence. These results provide support for the hypothesis that species facing greater selection pressure from parasites invest more in immune function. However, species with longer incubation periods mounted weaker cellular immune responses than species with shorter periods. Therefore, cellular immune responses do not support the hypothesis that longer development time enhances immunocompentence. Future studies should assess other components of the immune system and test alternative causes of variation in incubation periods among bird species.

  5. Incubation period and immune function: A comparative field study among coexisting birds

    USGS Publications Warehouse

    Palacios, M.G.; Martin, T.E.

    2006-01-01

    Developmental periods are integral components of life history strategies that can have important fitness consequences and vary enormously among organisms. However, the selection pressures and mechanisms causing variation in length of developmental periods are poorly understood. Particularly puzzling are prolonged developmental periods, because their selective advantage is unclear. Here we tested the hypotheses that immune function is stronger in species that are attacked at a higher rate by parasites and that prolonged embryonic development allows the development of this stronger immune system. Through a comparative field study among 12 coexisting passerine bird species, we show that species with higher blood parasite prevalence mounted stronger cellular immune responses than species with lower prevalence. These results provide support for the hypothesis that species facing greater selection pressure from parasites invest more in immune function. However, species with longer incubation periods mounted weaker cellular immune responses than species with shorter periods. Therefore, cellular immune responses do not support the hypothesis that longer development time enhances immunocompentence. Future studies should assess other components of the immune system and test alternative causes of variation in incubation periods among bird species. ?? Springer-Verlag 2005.

  6. Utility of ten-second uptake periods for kinetic studies of serotonin uptake by intact platelets

    SciTech Connect

    Costa, J.L.; Kirk, K.L.; Stark, H.

    1981-09-01

    When washed human platelets accumulate serotonin (5HT), it is possible with the use of formaldehyde fixative to measure uptake over periods as short as 10 seconds. To evaluate the utility of these short times for kinetic studies of 5HT uptake, we have examined the accuracy with which the 10 second uptake rate reflects changes in the extracellular 5HT concentration. The amount of 5HT taken up over a 10 second period appears to be determined by the concentration of 5HT present in the extracellular medium during that time period, and the uptake rate can change rapidly following sudden changes in the extracellular 5HT concentration. However, the extent of inhibition of 5HT uptake in the presence of imipramine of extracellular 5HT concentrations greater than 10-5M is somewhat different depending on whether the 5HT is allowed to accumulate for a 10-second or a 5- or 10-minute uptake period. A 10-second uptake period thus appears to be useful for kinetic studies of initial 5HT uptake velocities under normal conditions, but under inhibitory conditions may give results differing from those obtained with minute-long periods.

  7. Distinct lymphocyte antigens 6 (Ly6) family members Ly6D, Ly6E, Ly6K and Ly6H drive tumorigenesis and clinical outcome

    PubMed Central

    Luo, Linlin; McGarvey, Peter; Madhavan, Subha; Kumar, Rakesh; Gusev, Yuriy; Upadhyay, Geeta

    2016-01-01

    Stem cell antigen-1 (Sca-1) is used to isolate and characterize tumor initiating cell populations from tumors of various murine models [1]. Sca-1 induced disruption of TGF-β signaling is required in vivo tumorigenesis in breast cancer models [2, 3-5]. The role of human Ly6 gene family is only beginning to be appreciated in recent literature [6-9]. To study the significance of Ly6 gene family members, we have visualized one hundred thirty gene expression omnibus (GEO) dataset using Oncomine (Invitrogen) and Georgetown Database of Cancer (G-DOC). This analysis showed that four different members Ly6D, Ly6E, Ly6H or Ly6K have increased gene expressed in bladder, brain and CNS, breast, colorectal, cervical, ovarian, lung, head and neck, pancreatic and prostate cancer than their normal counter part tissues. Increased expression of Ly6D, Ly6E, Ly6H or Ly6K was observed in sub-set of cancer type. The increased expression of Ly6D, Ly6E, Ly6H and Ly6K was found to be associated with poor outcome in ovarian, colorectal, gastric, breast, lung, bladder or brain and CNS as observed by KM plotter and PROGgeneV2 platform. The remarkable findings of increased expression of Ly6 family members and its positive correlation with poor outcome on patient survival in multiple cancer type indicate that Ly6 family members Ly6D, Ly6E, Ly6K and Ly6H will be an important targets in clinical practice as marker of poor prognosis and for developing novel therapeutics in multiple cancer type. PMID:26862846

  8. Interface Trap Profiles in 4H- and 6H-SiC MOS Capacitors with Nitrogen- and Phosphorus-Doped Gate Oxides

    NASA Astrophysics Data System (ADS)

    Jiao, C.; Ahyi, A. C.; Dhar, S.; Morisette, D.; Myers-Ward, R.

    2017-04-01

    We report results on the interface trap density ( D it) of 4H- and 6H-SiC metal-oxide-semiconductor (MOS) capacitors with different interface chemistries. In addition to pure dry oxidation, we studied interfaces formed by annealing thermal oxides in NO or POCl3. The D it profiles, determined by the C- ψ s method, show that, although the as-oxidized 4H-SiC/SiO2 interface has a much higher D it profile than 6H-SiC/SiO2, after postoxidation annealing (POA), both polytypes maintain comparable D it near the conduction band edge for the gate oxides incorporated with nitrogen or phosphorus. Unlike most conventional C- V- or G- ω-based methods, the C- ψ s method is not limited by the maximum probe frequency, therefore taking into account the "fast traps" detected in previous work on 4H-SiC. The results indicate that such fast traps exist near the band edge of 6H-SiC also. For both polytypes, we show that the total interface trap density ( N it) integrated from the C- ψ s method is several times that obtained from the high-low method. The results suggest that the detected fast traps have a detrimental effect on electron transport in metal-oxide-semiconductor field-effect transistor (MOSFET) channels.

  9. Solvation-induced σ-complex structure formation in the gas phase: a revisit to the infrared spectroscopy of [C6H6-(CH3OH)2]+.

    PubMed

    Mizuse, Kenta; Suzuki, Yuta; Mikami, Naohiko; Fujii, Asuka

    2011-10-20

    Structures of the [C(6)H(6)-(CH(3)OH)(2)](+) cluster cation are investigated with infrared (IR) spectroscopy. While the noncovalent type structure has been confirmed for the n = 1 cluster of [C(6)H(6)-(CH(3)OH)(n)](+), only contradictory interpretations have been given for the spectra of n = 2, in which significant changes have been observed with the Ar tagging. In the present study, we revisit IR spectroscopy of the n = 2 cluster from the viewpoint of the σ-complex structure, which includes a covalent bond formation between the benzene and methanol moieties. The observed spectral range is extended to the lower-frequency region, and the spectrum is measured with and without Ar and N(2) tagging. A strongly hydrogen-bonded OH stretch band, which is characteristic to the σ-complex structure, is newly found with the tagging. The remarkable spectral changes with the tagging are interpreted by the competition between the σ-complex and noncovalent complex structures in the [C(6)H(6)-(CH(3)OH)(2)](+) system. This result shows that the microsolvation only with one methanol molecule can induce the σ-complex structure formation.

  10. Carcass yields and meat quality characteristics of adult emus (Dromaius novaehollandiae) transported for 6h before slaughter.

    PubMed

    Menon, Deepa G; Bennett, Darin C; Uttaro, Bethany; Schaefer, Allan L; Cheng, Kimberly M

    2014-10-01

    The meat quality characteristics of adult emus transported for 6h before slaughter were determined. Forty-two emus were used in two trials, undertaken under warm and cool weather conditions, respectively. Male emus had significantly higher fat yields than females (12.43kg vs 9.5kg, P=0.002). About 38.1% of the emus had no wounds or bruises, 40.5% had bruises, while 21.4% had small wounds after transport. Meat from injured emus had significantly higher pH45. In warm weather, emus experienced significantly higher loss in body weight than that under cool weather. Drip loss in meat after 24h of storage was higher in emus which had greater live weight loss after transport (r=0.66, P<0.0001), confirming the adverse effects of transport stress on meat quality. Nutrient supplementation did not significantly affect processing yield or meat quality characteristics. This study points to the need for optimizing transport conditions of emus to maintain meat quality.

  11. Suppression of Photoanodic Surface Oxidation of n-Type 6H-SiC Electrodes in Aqueous Electrolytes.

    PubMed

    Sachsenhauser, Matthias; Walczak, Karl; Hampel, Paul A; Stutzmann, Martin; Sharp, Ian D; Garrido, Jose A

    2016-02-16

    The photoelectrochemical characterization of silicon carbide (SiC) electrodes is important for enabling a wide range of potential applications for this semiconductor. However, photocorrosion of the SiC surface remains a key challenge, because this process considerably hinders the deployment of this material into functional devices. In this report, we use cyclic voltammetry to investigate the stability of n-type 6H-SiC photoelectrodes in buffered aqueous electrolytes. For measurements in pure Tris buffer, photogenerated holes accumulate at the interface under anodic polarization, resulting in the formation of a porous surface oxide layer. Two possibilities are presented to significantly enhance the stability of the SiC photoelectrodes. In the first approach, redox molecules are added to the buffer solution to kinetically facilitate hole transfer to these molecules, and in the second approach, water oxidation in the electrolyte is induced by depositing a cobalt phosphate catalyst onto the semiconductor surface. Both methods are found to effectively suppress photocorrosion of the SiC electrodes, as confirmed by atomic force microscopy and X-ray photoelectron spectroscopy measurements. The presented study provides straightforward routes to stabilize n-type SiC photoelectrodes in aqueous electrolytes, which is essential for a possible utilization of this material in the fields of photocatalysis and multimodal biosensing.

  12. Electroencephalography Spectral Power Density in First-Episode Mania: A Comparative Study with Subsequent Remission Period

    PubMed Central

    GÜVEN, Sertaç; KESEBİR, Sermin; DEMİRER, R. Murat; BİLİCİ, Mustafa

    2015-01-01

    Introduction Our aim in this study was to investigate spectral power density (PSD) in first-episode mania and subsequent remission period and to evaluate their difference. Methods Sixty-nine consecutive cases referring to our hospital within the previous 1 year, who were evaluated as bipolar disorder manic episode according to The Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) at the first episode and had the informed consent form signed by first degree relatives, were included in this study. Exclusion criteria included having previous depressive episode, using drugs which could influence electroencephalographic activity before electroencephalography (EEG), and having previous neurological disease, particularly epilepsy, head trauma, and/or loss of consciousness. EEG records were obtained using a digital device in 16 channels; 23 surface electrodes were placed according to the International 10–20 system. Spectral power density (dbμV/Hz) of EEG signal provided information on the power carried out by EEG waves in defined frequancy range per unit frequency in the present study. Results A peak power value detected on the right with FP2P4 and on the left with F7T3 electrodes were found to be higher in the manic episode than in the remission period (p=0.018 and 0.025). In the remission period, in cases with psychotic symptoms during the manic period, F4C4 peak power value was found to be lower than that in cases with no psychotic findings during the manic period (p=0.027). There was no relation was found between YMRS scores and peak power scores. Conclusion Electrophysiological corollary of mood episode is present from the onset of the disease, and it differs between the manic and remission periods of bipolar disorder. In the remission period, peak power values of PSD distinguish cases with psychotic findings from cases without psychotic findings when they were manic.

  13. Nucleation Mechanism of 6H-SiC Polytype Inclusions Inside 15R-SiC Crystals

    SciTech Connect

    Zhang, Y.; Zhang, L.; Chen, H.; Choi, G.; Raghothamachar, B.; Dudley, M.; Edgar, J.H.; Grasza, K.; Tymicki, E.; Su, D.; Zhu, Y.

    2010-06-01

    A model is presented for the nucleation mechanism of 6H-SiC polytype inclusions inside 15R-SiC boules. Inhomogeneous densities of screw dislocations lead to uneven growth rates, resulting in complex step overgrowth processes which can partially suppress the Burgers vector of a 15R 1c screw dislocation through the creation of Frank faults and Frank partial dislocations. Combined with stacking shifts induced by the passage of basal plane partial dislocations, it is shown that the partial Burgers vector suppression can leave behind a residual 6H 1c dislocation, which then acts as a nucleus for reproduction of 6H-SiC structure in the 15R-SiC crystal.

  14. New Light Curves and Period Studies of V502 OPH W UMA System

    NASA Astrophysics Data System (ADS)

    Awadalla, Nabil S.

    NEW LIGHT CURVES AND PERIOD STUDIES OF V502 OPH W UMa SYSTEM N.S.Awadalla National Research Institute of Astronomy and Geophysics( NRIAG ) Helwan Cairo EGYPT New BVR photoelectric observations of the W UMa eclipsing binary system V502 Oph have been presented and analyzed. The geometric and physical elements of the system have been obtained and compared to the previous results. The classification of the system concerning the sub-type of the W UMa binary has been studied as well as its evolution stage. Its period variation in a view of the light time effect has been examin

  15. Split-field FDTD method for oblique incidence study of periodic dispersive metallic structures.

    PubMed

    Baida, F I; Belkhir, A

    2009-08-15

    The study of periodic structures illuminated by a normally incident plane wave is a simple task that can be numerically simulated by the finite-difference time-domain (FDTD) method. On the contrary, for off-normal incidence, a widely modified algorithm must be developed in order to bypass the frequency dependence appearing in the periodic boundary conditions. After recently implementing this FDTD algorithm for pure dielectric materials, we here extend it to the study of metallic structures where dispersion can be described by analytical models. The accuracy of our code is demonstrated through comparisons with already-published results in the case of 1D and 3D structures.

  16. 1,1'-Fc(4-C6H4CO2Et)2 and its unusual salt derivative with Z' = 5, catena-[Na+]2[1,1'-Fc(4-C6H4CO2-)2].0.6H2O [1,1'-Fc = (eta5-(C5H4)2Fe].

    PubMed

    Gallagher, John F; Alley, Steven; Brosnan, Marianne; Lough, Alan J

    2010-04-01

    The neutral diethyl 4,4'-(ferrocene-1,1'-diyl)dibenzoate, Fe[eta(5)-(C(5)H(4))(4-C(6)H(4)CO(2)Et)](2) (I), yields (II) (following base hydrolysis) as the unusual complex salt poly[disodium bis[diethyl 4,4'-(ferrocene-1,1'-diyl)dibenzoate] 0.6-hydrate] or [Na(+)](2)[Fe{eta(5)-(C(5)H(4))-4-C(6)H(4)CO(2)(-)}(2)].0.6H(2)O with Z' = 5. Compound (I) crystallizes in the triclinic system, space group P1, with two molecules having similar geometry in the asymmetric unit (Z' = 2). The salt complex (II) crystallizes in the orthorhombic system, space group Pbca, with the asymmetric unit comprising poly[decasodium pentakis[diethyl 4,4'-(ferrocene-1,1'-diyl)dibenzoate] trihydrate] or [Na(+)](10)[Fe{eta(5)-(C(5)H(4))-4-C(6)H(4)CO(2)(-)}(2)](5).3H(2)O. The five independent 1,1'-Fc[(4-C(6)H(4)CO(2))(-)](2) dianions stack in an offset ladder (stepped) arrangement with the ten benzoates mutually oriented cisoid towards and bonded to a central layer comprising the ten Na(+) ions and three water molecules [1,1'-Fc = eta(5)-(C(5)H(4))(2)Fe]. The five dianions differ in the cisoid orientations of their pendant benzoate groups, with four having their -C(6)H(4)- groups mutually oriented at interplanar angles from 0.6 (3) to 3.2 (3) degrees (as pi...pi stacked C(6) rings) and interacting principally with Na(+) ions. The fifth dianion is distorted and opens up to an unprecedented -C(6)H(4)- interplanar angle of 18.6 (3) degrees through bending of the two 4-C(6)H(4)CO(2) groups and with several ionic interactions involving the three water molecules (arranged as one-dimensional zigzag chains in the lattice). Overall packing comprises two-dimensional layers of Na(+) cations coordinated mainly by the carboxylate O atoms, and one-dimensional water chains. The non-polar Fc(C(6)H(4))(2) groups are arranged perpendicular to the layers and mutually interlock through a series of efficient C-H...pi stacking contacts in a herringbone fashion to produce an overall segregation of polar and non

  17. Synthesis, structural and magnetic characterisation of the fully fluorinated compound 6H-BaFeO{sub 2}F

    SciTech Connect

    Clemens, Oliver; Wright, Adrian J.; Berry, Frank J.; Smith, Ronald I.; Slater, Peter R.

    2013-02-15

    The compound 6H-BaFeO{sub 2}F (P6{sub 3}/mmc) was synthesised by the low temperature fluorination of 6H-BaFeO{sub 3-d} using polyvinylidenedifluoride (PVDF) as a fluorination agent. Structural characterisation by XRD and NPD suggests that the local positions of the oxygen and fluorine atoms vary with no evidence for ordering on the anion sites. This compound shows antiferromagnetic ordering at room temperature with antiparallel alignment of the magnetic moments along the c-axis. The use of PVDF also allows the possibility of tuning the fluorine content in materials of composition 6H-BaFeO{sub 3-d}F{sub y} to any value of 06H-BaFeO{sub 2}F. Highlights: Black-Right-Pointing-Pointer The crystal structure of the hexagonal perovskite phase 6H-BaFeO{sub 2}F. Black-Right-Pointing-Pointer H-BaFeO{sub 2}F and 6H-BaFeO{sub 3-d}F{sub y} were prepared via low temperature fluorination using PVDF. Black-Right-Pointing-Pointer A structural investigation of the compounds BaFeO{sub 2}F is presented in detail. Black-Right-Pointing-Pointer This analysis suggests differences for the local coordination of O{sup 2-} and F{sup -} anions. Black-Right-Pointing-Pointer H-BaFeO{sub 2}F shows antiferromagnetic ordering at 300 K. Black-Right-Pointing-Pointer The magnetic moments align parallel to the a-axis.

  18. Environmental input and cognitive growth: a study using time-period comparisons.

    PubMed

    Huttenlocher, J; Levine, S; Vevea, J

    1998-08-01

    In this study, we examined the relation of input to cognitive growth in a single population of children. We studied 4 domains: Language, Spatial Operations, Concepts, and Associative Memory. Four groups of children drawn from the same population were tested in October of kindergarten, April of kindergarten, October of first grade, and April of first grade. These time points are 6 months apart, but they span periods that differ in amount of school input children receive. Much greater growth was found over time periods with greater amounts of school input (October to April) than over time periods with less school input (April to October) for Language, Spatial Operations, and Concepts, but not for Associative Memory. These findings suggest that amount of input is causally related to cognitive growth in particular domains.

  19. Band alignment of InN/6H-SiC heterojunction determined by x-ray photoelectron spectroscopy

    SciTech Connect

    Jing, Qiang; Wu, Guoguang; Zhang, Yuantao; Gao, Fubin; Cai, Xupu; Zhao, Yang; Li, Wancheng Du, Guotong

    2014-08-11

    The valence band offset (VBO) of InN/6H-SiC heterojunction has been directly measured by x-ray photoelectron spectroscopy. The VBO is determined to be −0.10 ± 0.23 eV and the conduction band offset is deduced to be −2.47 ± 0.23 eV, indicating that the heterojunction has a type-II band alignment. The accurate determination of the valence and conduction band offsets is important for applications and analysis of InN/6H-SiC optoelectronic devices.

  20. A New Method for Studying the Periodic System Based on a Kohonen Neural Network

    ERIC Educational Resources Information Center

    Chen, David Zhekai

    2010-01-01

    A new method for studying the periodic system is described based on the combination of a Kohonen neural network and a set of chemical and physical properties. The classification results are directly shown in a two-dimensional map and easy to interpret. This is one of the major advantages of this approach over other methods reported in the…

  1. Extended AB period study of the electron pairing transition in t-J ladders

    SciTech Connect

    Kusakabe, Koichi; Aoki, Hideo

    1996-11-01

    The extended Aharonov-Bohm period test, recently proposed by the present authors, is used to study the electron pairing transition in the t-J ladders. The critical point is detected as a gap opening in the extended spectral flow. The result suggests a pairing prior to the onset of a phase separation, which is consistent with a recent Tomonaga-Luttinger analysis.

  2. Doubly periodic structure for the study of inhomogeneous bulk fermion matter with spatial localizations

    SciTech Connect

    Vantournhout, Klaas; Jachowicz, Natalie; Ryckebusch, Jan

    2011-09-15

    We present a method that offers perspectives to perform fully antisymmetrized simulations for inhomogeneous bulk fermion matter. The technique bears resemblance to classical periodic boundary conditions, using localized single-particle states. Such localized states are an ideal tool to discuss phenomena where spatial localization plays an important role. The antisymmetrization is obtained introducing a doubly periodic structure in the many-body fermion wave functions. This results in circulant matrices for the evaluation of expectation values, leading to a computationally tractable formalism to study fully antisymmetrized bulk fermion matter. We show that the proposed technique is able to reproduce essential fermion features in an elegant and computationally advantageous manner.

  3. Study on the Geomagnetic Short Period Variations of the Northwestern Yunnan

    NASA Astrophysics Data System (ADS)

    Yuan, Y.; Li, Q.; Cai, J.

    2015-12-01

    The Northwestern Yunnan is located in the interaction area between the Eurasian plate and the India plate. This area has been the ideal place for the research of continental dynamics and the prediction for risk region of strong earthquake for its complex tectonic environment and frequent seismic activity. Therefore the study on the geomagnetic short period variations is of great significance in the exploration of deep electrical structure, analysis of the seismic origin and deep geodynamics in the Northwestern Yunnan of China . This paper is based on the geomagnetic data from the magnetometer array with 8 sites built in the northwestern Yunnan to explore the deep electrical structure by the method of geomagnetic depth sounding. Firstly, we selected a total of 183 geomagnetic short period events at the range of 6min to 120min period. And we found a north northwest dividing line, of which two sides has the opposite value in the vertical component variation amplitude, which indicates the obvious conductivity anomaly underground. Secondly, the contour maps of the ratio of vertical component and horizontal component variation amplitude ΔZ/ΔH in different periods reflects the changes of a high conductivity belt's direction and position. In addition, the induction arrows maps within the period of 2 - 256min also shows that on the two sides of the dividing line the induction vectors deviate from each other, and the amplitude and direction of vectors varies with periods regularly. In the light of this, we infer that a high conductivity belt probably exists, which stretches from the deep crust to uppermost mantle and changes with depth constantly with the reference of magnetotelluric sounding. In the end of this paper, the staggered grid finite difference method is used to model the simplified three-dimensional high conductivity anomaly, and the result shows magnetic field distributions are consistent with the observed geomagnetic short period variations characteristics in

  4. Study of the period changes in SW Dor, an RR Lyrae type star with Blazhko effect

    NASA Astrophysics Data System (ADS)

    Berdnikov, L. N.; Kniazev, A. Y.; Dambis, A. K.; Kravtsov, V. V.; Sefako, R.

    2016-09-01

    In 2012-2014 we acquired 1569 CCD BVIc frames for the RR Lyrae type variable SW Dor with the 76-cm telescope of the South African Astronomical Observatory (SAAO) and 1-m telescopes of Las Cumbres Observatory Global Telescope network (LCOGT). Our observations showed a large scatter in the resulting phased light curve, especially near maximum brightness, which allowed us to reveal the Blazhko effect with a period of ˜80.9d. To study the pulsation period changes, we used all the available observations including the 1299 magnitude estimates from the digitized plate library of Harvard University (the DASCH project), which allowed us to construct the O-C diagram spanning a 125-year long time interval and discover for the first time at least three abrupt changes of the pulsation period.

  5. Ionic adsorption on the brucite (0001) surface: A periodic electrostatic embedded cluster method study

    NASA Astrophysics Data System (ADS)

    Makkos, Eszter; Kerridge, Andrew; Austin, Jonathan; Kaltsoyannis, Nikolas

    2016-11-01

    Density functional theory (DFT) at the generalised gradient approximation level is employed within the periodic electrostatic embedded cluster method (PEECM) to model the brucite (0001) surface. Three representative studies are then used to demonstrate the reliability of the PEECM for the description of the interactions of various ionic species with the layered Mg(OH)2 structure, and its performance is compared with periodic DFT, an approach known to be challenging for the adsorption of charged species. The adsorption energies of a series of s block cations, including Sr2+ and Cs+ which are known to coexist with brucite in nuclear waste storage ponds, are well described by the embedded cluster model, provided that basis sets of triple-zeta quality are employed for the adsorbates. The substitution energies of Ca2+ and Sr2+ into brucite obtained with the PEECM are very similar to periodic DFT results, and comparison of the approaches indicates that two brucite layers in the quantum mechanical part of the PEECM are sufficient to describe the substitution. Finally, a detailed comparison of the periodic and PEECM DFT approaches to the energetic and geometric properties of differently coordinated Sr[(OH)2(H2O)4] complexes on brucite shows an excellent agreement in adsorption energies, Sr-O distances, and bond critical point electron densities (obtained via the quantum theory of atoms-in-molecules), demonstrating that the PEECM can be a useful alternative to periodic DFT in these situations.

  6. Multiperiodicity in quasi-periodic pulsations of flare hard X-rays: a case study

    NASA Astrophysics Data System (ADS)

    Tomczak, M.; Szaforz, Ż.

    We present a case study of the solar flare (SOL2001-10-02T17:31) that showed quasi-periodic pulsations (QPPs) in hard X-rays with two simultaneously excited periods, P_1 = 26-31 s and P_2 = 110 s. Complete evolution of the flare recorded by the Yohkoh telescopes, together with the patrol SOHO/EIT images, allowed us to identify magnetic structures responsible for particular periods and to propose an overall scenario which is consistent with the available observations. Namely, we suggest that emerging magnetic flux initiated the reconnection with legs of a large arcade of coronal loops that had been present in an active region for several days. The reconnection excited MHD oscillations in both magnetic structures simultaneously: period P_1 was generated in the emerging loop and in a loop being a result of the reconnection; period P_2 occurred in the arcade. Both resonators produced photons of different spectra. We anticipate that multiperiodicity in hard X-rays can be a common feature of flare hybrids, i.e. the events, in which magnetic structures of different sizes interact.

  7. Identification and transcriptional profile of multiple genes in the posterior kidney of Nile tilapia at 6h post bacterial infections

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To understand the molecular mechanisms involved in response of Nile tilapia (Oreochromis niloticus) to bacterial infection, suppression subtractive cDNA hybridization technique was used to identify upregulated genes in the posterior kidney of Nile tilapia at 6h post infection with Aeromonas hydrophi...

  8. Reaction of 6H-6-oxo-3(5)-halogenoanthra(1,9-cd)isoxazoles with inorganic nucleophiles

    SciTech Connect

    Gornostaev, L.M.; Zeibert, G.F.

    1986-11-20

    The reaction of 6H-6-oxo-3(5)-halogenoanthral(1,9-cd)isoxazoles with sodium azide in DMFA and also the potassium fluoride in acetonitrile in the presence of crown ethers leads to nucleophilic substitution of the halogen by the azide and fluoride ion respectively.

  9. N-V{sub Si}-related center in non-irradiated 6H SiC nanostructure

    SciTech Connect

    Bagraev, Nikolay; Danilovskii, Eduard; Gets, Dmitrii; Klyachkin, Leonid; Malyarenko, Anna; Kalabukhova, Ekaterina; Shanina, Bella; Savchenko, Dariya

    2014-02-21

    We present the first findings of the vacancy-related centers identified by the electron spin resonance (ESR) and electrically-detected (ED) ESR method in the non-irradiated 6H-SiC nanostructure. This planar 6H-SiC nanostructure represents the ultra-narrow p-type quantum well confined by the δ-barriers heavily doped with boron on the surface of the n-type 6H-SiC (0001) wafer. The EDESR method by measuring the only magnetoresistance of the 6H SiC nanostructure under the high frequency generation from the δ-barriers appears to allow the identification of the silicon vacancy centers as well as the triplet center with spin state S=1. The same triplet center that is characterized by the larger value of the zero-field splitting constant D and anisotropic g-factor is revealed by the ESR (X-band) method. The hyperfine (hf) lines in the ESR and EDESR spectra originating from the hf interaction with the {sup 14}N nucleus allow us to attribute this triplet center to the N-V{sub Si} defect.

  10. Laboratory submillimeter transition frequencies of Li-7H and Li-6H. [used for abundance investigations in red giant stars

    NASA Technical Reports Server (NTRS)

    Plummer, G. M.; Herbst, E.; De Lucia, F. C.

    1984-01-01

    The fundamental (J = 1 - 0) rotational transition frequencies of Li-7H and Li-6H in their ground (v = 0) vibrational states and of Li-7H in its first excited (v = 1) vibrational state have been measured in the laboratory. Use of these transition frequencies should permit astronomical investigations of LiH abundances in red giant stars of high lithium abundance.

  11. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Formaldehyde, polymer with... Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6... identified as formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with...

  12. 40 CFR 721.5560 - Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz[c...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Formaldehyde, polymer with... Formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with 6H-dibenz oxaphosphorin-6... identified as formaldehyde, polymer with (chloromethyl) oxirane and phenol, reaction products with...

  13. Measuring rotation periods of solar-like stars using TIGRE. A study of periodic CaII H+K S-index variability

    NASA Astrophysics Data System (ADS)

    Hempelmann, A.; Mittag, M.; Gonzalez-Perez, J. N.; Schmitt, J. H. M. M.; Schröder, K. P.; Rauw, G.

    2016-02-01

    Context. The rotation period of a star is a key parameter both for the stellar dynamo that generates magnetic fields as well as for stellar differential rotation. Aims: We present the results from the first year of monitoring a sample of solar-like stars by the TIGRE facility in Guanajuato (Mexico), which will study rotation in solar analogs. Methods: TIGRE is an automatically operating 1.2 m telescope equipped with an Échelle spectrograph with a spectral resolution of 20 000, which covers a spectral range of between 3800 and 8800 Å. A main task is the monitoring the stellar activity of cool stars, mainly in the emission cores of the CaII H and K lines. We observed a number of stars with a sampling between 1-3 days over one year. Results: A total number of 95 stars were observed between August 1 2013 and July 31 2014, the total number of spectra taken for this program was appoximately 2700. For almost a third of the sample stars the number of observations was rather low (less than 20), mainly because of bad weather. Fifty-four stars show a periodic signal but often with low significance. Only 24 stars exhibit a significant period. We interpret these signals as stellar rotation. For about half of them the rotation periods were already previously known, in which case our period measurements are usually in good agreement with the literature values. Besides the periodic signals, trends are frequently observed in the time series. Conclusions: TIGRE is obviously able to detect stellar rotation periods in the CaII H+K emission cores when the time series contains a sufficient number of data points. However, this is frequently not achievable during the wet summer season in Guanajuato. Hence, future estimates of rotation periods will concentrate on stars that are observable during the winter season from October until April.

  14. Retrospective study of recession of four horizontal rectus muscle in periodic alternating nystagmus

    PubMed Central

    Mimura, Osamu; Ishikawa, Hiroto; Kimura, Naoki; Kimura, Akiko; Borlongan, Cesar V

    2014-01-01

    Purpose Periodic alternating nystagmus (PAN) is a spontaneous horizontal nystagmus observed in disorders of the central nervous system. Patients with congenital PAN complain of oscillating vision at high rates. Medication is the first-choice treatment for PAN; however, clinicians still seek better therapy. The aim of this study was to evaluate outcomes of recession of four horizontal rectus muscle (R-FHR) in patients with congenital PAN. Patients and methods This study reports a retrospective case series of ten patients (seven males and three females; mean age 24.4±10.9) with congenital PAN who underwent R-FHR between 2007 and 2012, which was performed by the same surgeon at the Hyogo College of Medicine. Patients were evaluated for complications, recession amount, deviation angle, eye movements including a nystagmus amplitude, and visual acuity during pre- and post-operative periods. Results Pre-operatively, patients complained of oscillating vision, abnormal head posture, esotropia, and congenital superior oblique palsy. Post-operatively, changes from the previous observations of nystagmus amplitudes and abnormal head posture demonstrated a complete reversal in all patients. In addition, visual acuity determined with a Snellen chart improved in two patients. However, esotropia occurred in three patients who underwent additional strabismus surgery 2 days after R-FHR. R-FHR was particularly effective in eight patients who pre-operatively had periodic oscillating vision with a regular pattern of periodic nystagmus. Conclusion We demonstrated that ten patients with congenital PAN had improved vision following R-FHR, indicating that R-FHR was an effective procedure, especially in patients suffering PAN with periodic oscillating vision. PMID:25525330

  15. A study of the shortest-period planets found with Kepler

    SciTech Connect

    Sanchis-Ojeda, Roberto; Rappaport, Saul; Winn, Joshua N.; Kotson, Michael C.; Levine, Alan; Mellah, Ileyk El E-mail: sar@mit.edu E-mail: ileyk@apc.univ-paris7.fr

    2014-05-20

    We present the results of a survey aimed at discovering and studying transiting planets with orbital periods shorter than one day (ultra-short-period, or USP, planets), using data from the Kepler spacecraft. We computed Fourier transforms of the photometric time series for all 200,000 target stars, and detected transit signals based on the presence of regularly spaced sharp peaks in the Fourier spectrum. We present a list of 106 USP candidates, of which 18 have not previously been described in the literature. This list of candidates increases the number of planet candidates with orbital periods shorter than about six hours from two to seven. In addition, among the objects we studied, there are 26 USP candidates that had been previously reported in the literature which do not pass our various tests. All 106 of our candidates have passed several standard tests to rule out false positives due to eclipsing stellar systems. A low false positive rate is also implied by the relatively high fraction of candidates for which more than one transiting planet signal was detected. By assuming these multi-transit candidates represent coplanar multi-planet systems, we are able to infer that the USP planets are typically accompanied by other planets with periods in the range 1-50 days, in contrast with hot Jupiters which very rarely have companions in that same period range. Another clear pattern is that almost all USP planets are smaller than 2 R {sub ⊕}, possibly because gas giants in very tight orbits would lose their atmospheres by photoevaporation when subject to extremely strong stellar irradiation. Based on our survey statistics, USP planets exist around approximately (0.51 ± 0.07)% of G-dwarf stars, and (0.83 ± 0.18)% of K-dwarf stars.

  16. Study of the resonances of periodic plane media immersed in water: theory and experiment.

    PubMed

    Khaled, Aissam; Maréchal, Pierre; Lenoir, Olivier; Ech-Cherif El-Kettani, Mounsif; Chenouni, Driss

    2013-03-01

    The paper deals with the study of the resonances of 1D periodic media composed of N elementary cells formed with two perfectly bonded layers which exhibit a high acoustic impedance contrast. In the case of a periodic bilayer structure constituted of a fluid layer and an elastic plate, it was shown in previous theoretical works that additional modes appear compared to those of a single plate. These are called structure modes. At low frequency, the so-called vertical modes are found. Approximate expressions of their cut-off frequencies are given and their numerical values match with the exact ones. At high frequency, the Lamb type modes are degenerated and modes in the fluid layers are also observed. Preliminary experimental results have already proved the existence of such phenomena for one and two periods. In our work, an experimental validation has been performed in the case of N periods made with a glass isotropic elastic plate and a water fluid layer, where the number N ranges from two to five. A good agreement is shown compared to theoretical works.

  17. Mössbauer studies on ancient chinese pottery of Yangshao Culture Period

    NASA Astrophysics Data System (ADS)

    Yu, Zhengfang; Zheng, Qi; Zheng, Yufang

    1988-12-01

    Eleven pieces of ancient Chinese pottery (4770 B.C. 2960 B.C.) of Yangshao Culture Period collected from the Xi'an area have been studied by means of Mössbauer spectroscopy. The samples were refired up to 1100°C in steps of 100°C for 2h in air. The highest temperature up to which the Mössbauer pattern remains basically unchanged can be identified with the original firing temperature. The result indicates that the firing temperatures for most of the sherds were between 900 1000°C. The function of the grit contained in the pottery has been discussed. The crimson and reddish painted materials on the surface of sherds have been studied, respectively. The first appearance of pottery can probably be traced back to an even earlier period.

  18. Study of biological rhythms of small intestinal cryptic epithelial mitosis of different periodicity by fourier analysis.

    PubMed

    Romanov, Yu A; Zharkova, N A; Antochin, A I; Zakharchenko, A V

    2009-05-01

    Rhythms of cell division with different periods in the mouse small intestinal cryptic epithelium were studied using Fourier analysis. It was found that the proliferative system of the crypt is characterized by an intricate spatial and temporal organization. The amplitude of low-frequency rhythms increases, while the amplitude of high-frequency rhythms decreased in the direction from the crypt bottom to the neck.

  19. Synthesis and characterisation of a new hydrated bismuth (III) oxalate : Bi2(C2O4)3,6H2O

    NASA Astrophysics Data System (ADS)

    Tortet, L.; Monnereau, O.; Roussel, P.; Conflant, P.

    2004-11-01

    This study presents results on synthesis and crystal structure of a new hydrated bismuth(III) oxalate : Bi2(C2O{4})3,6H2O. This compound is obtained by precipitation from Bi(NO3)3 solution and oxalic acid. Its structure is determined by X-ray crystallographic analysis from a single crystal: it is monoclinic with a = 9.761(1)Å, b = 8.193(1)Å, c = 10.214(1)Å, β = 99.66(1)circ, G.S. P2{1}/n. Its chemical composition is confirmed by chemical analyses, FTIR and TG-DTA experiments.

  20. Elemental analysis of mixed K2Ni x Co1- x (SO4)2 • 6H2O crystals

    NASA Astrophysics Data System (ADS)

    Vasilyeva, N. A.; Nuzhdin, D. S.; Faddeev, M. A.; Grebenev, V. V.; Lykov, V. A.; Voloshin, A. E.

    2016-03-01

    Mixed K2Ni x Co(1- x)(SO4)2 • 6H2O crystals have been grown by spontaneous crystallization and lowering the solution temperature. The samples have been studied by atomic emission spectroscopy and electron probe X-ray microanalysis. A large difference between the contents of isomorphic components in different crystal growth sectors is revealed. The dependence of the crystal composition on the mother liquor composition is plotted. The component distribution along the crystal growth direction is analyzed.

  1. The three-level ripples induced by femtosecond laser on a 6H-SiC single crystal and the formation mechanism

    NASA Astrophysics Data System (ADS)

    Song, Juan; Tao, Wenjun; Gong, Min; Ye, Junyi; Dai, Ye; Ma, Guohong; Qiu, Jianrong

    2016-04-01

    In this paper, a line-scanning irradiation of <0001> 6H-SiC single crystal by a femtosecond laser focus was implemented for laser fluence of 2.2 J/cm2 at different scanning velocities from 1000 down to 100 μm/s. The morphology of the obtained ablation lines characterized by a scanning electron microscope shows that there progressively appear three-level ripples with average period of about 222, 600 nm and that between them. Possible formation mechanisms for these three-level ripples were analyzed by numerical simulation employing finite-difference time-domain method (FDTD). Analysis shows that as Obara proposed, the interference of incident wave with the wave scattered by scratches possibly left by fine polishing is the most possible reason for inducing 222 nm-period and 600 nm-period ripples. Main discussions were focused on the orientation characteristics of ripples. Both isolated scratches and crossed scratches with different orientation angles were considered for evaluating their role in field redistribution. The detailed simulations indicate that for scratches oriented 90° with respect to laser polarization generate a pair of strongest ripple-like optical field enhancement compared to scratches with other orientation angles. It is these advantages of 90°-oriented scratch in field enhancement that make the final ripple perpendicular to laser polarization most competitive and finally left on the surface. This complements the physical picture of Obara et al. in terms of their negligence in addressing the orientation characteristics of ripples. Further FDTD simulation of the interaction of incident wave with as-formed 600 nm-period ripples shows that the optical field enhancement located between any two adjacent 600 nm-period ripples is the driving force for splitting 600 nm-period ripples into the third ripples with period between 222 and 600 nm.

  2. Identification of 6H-SiC polar faces with pull-off force of atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Gan, Di; Song, Youting; Yang, Junwei; Chen, Hongxiang; Guo, Liwei; Chen, Xiaolong

    2016-12-01

    Distinguishing SiC (0001) Si-face from SiC (000-1) C-face without any damages is extremely important because the two polar faces have different physical and chemical properties which seriously influence the quality of a homoepitaxy or heteroepitaxy thin film on it. Here, a convenient and nondestructive detection method is developed to distinguish the Si-face and C-face of a (0001) oriented SiC wafer by employing a pull-off force measurement using atomic force microscopy. It is found that the pull-off force from a Si-face of 6H-SiC is about two times of that from a C-face, no matter it is a two-face chemical mechanical polishing or etched 6H-SiC wafer. The method developed here is suitable to identify polar faces of materials only if the two polar faces having different surface energy.

  3. Current transport property of n-GaN /n-6H-SiC heterojunction: Influence of interface states

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Chen, X. D.; Fung, S.; Beling, C. D.; Ling, C. C.; Dai, X. Q.; Xie, M. H.

    2005-03-01

    Heterostructures of n-GaN /n-6H-SiC grown by hydride vapor phase epitaxy (HVPE) and molecular-beam epitaxy (MBE) are characterized with the current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) techniques. Using different contact configurations, the I -V results reveal a rectifying barrier in the n-GaN /n-6H-SiC heterostructures. When GaN is negatively biased, the current is exponentially proportional to the applied voltage with the built-in barrier being 0.4-1.1eV for the HVPE samples and 0.5eV for the MBE sample. DLTS measurements reveal intense band-like deep level states in the interfacial region of the heterostructure, and the Fermi-level pinning by these deep level defects is invoked to account for the interfacial rectifying barrier of the heterostructures.

  4. On Flowfield Periodicity in the NASA Transonic Flutter Cascade. Part 1; Experimental Study

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; McFarland, E. R.; Chima, R. V.; Wood, J. R.

    2000-01-01

    An extensive study to improve flow uniformity and periodicity in the NASA Transonic Flutter Cascade is presented here. The results are reported in two independent parts dealing with the experimental approach and the analytical approach. The first part, the Experimental Study, focuses first on the data sets acquired in this facility in the past and explains several discrepancies, particularly the questions of actual flow incidence and cascade back pressure levels. Next, available means for control and modifications of the cascade flowfield, boundary layer bleed and tailboard settings are presented in detail. This is followed by experimental data sets acquired in modified test facility configurations that were based on analytical predictions of the cascade flowfield. Finally, several important conclusions about improving the cascade flowfield uniformity and blade load periodicity are summarized. The important conclusions are: (1) boundary layer bleed does not improve the cascade flow periodicity; (2) tunnel wall contours must be carefully matched to the expected shape of cascade streamlines; (3) actual flow incidence for each cascade configuration rather must be measured instead of relying on the tunnel geometry; and (4) the current cascade configuration exhibits a very high blade load uniformity over six blades from blade #2 to blade #7, and the facility is now ready for unsteady pressure data acquisition.

  5. Studies of phase return map and symbolic dynamics in a periodically driven Hodgkin—Huxley neuron

    NASA Astrophysics Data System (ADS)

    Ding, Jiong; Zhang, Hong; Tong, Qin-Ye; Chen, Zhuo

    2014-02-01

    How neuronal spike trains encode external information is a hot topic in neurodynamics studies. In this paper, we investigate the dynamical states of the Hodgkin—Huxley neuron under periodic forcing. Depending on the parameters of the stimulus, the neuron exhibits periodic, quasiperiodic and chaotic spike trains. In order to analyze these spike trains quantitatively, we use the phase return map to describe the dynamical behavior on a one-dimensional (1D) map. According to the monotonicity or discontinuous point of the 1D map, the spike trains are transformed into symbolic sequences by implementing a coarse-grained algorithm — symbolic dynamics. Based on the ordering rules of symbolic dynamics, the parameters of the external stimulus can be measured in high resolution with finite length symbolic sequences. A reasonable explanation for why the nervous system can discriminate or cognize the small change of the external signals in a short time is also presented.

  6. Spectroscopic studies of wood fossils from the Crato Formation, Cretaceous Period.

    PubMed

    da Silva, J H; Freire, P T C; Abagaro, B T O; Silva, J A F; Saraiva, G D; de Lima, F J; Barros, O A; Bantim, R A; Saraiva, A A F; Viana, B C

    2013-11-01

    In this work we study two types of wood fossils (Gymnosperms, Araucariaceae) from the Crato Formation of Araripe Basin in Brazil, from the Cretaceous Period. The samples were characterized by Raman and infrared spectroscopies, X-ray diffraction and scanning electron microscopy. The results obtained by different techniques showed that although the rocks surrounding the fossils have predominantly the same constitution - calcite - however, the formation processes of these types of wood fossils are quite different. One of the fossils, denominated as light wood, is predominantly composed of gypsum, while the other fossil, the dark wood, is rich in amorphous carbon, possibly the kerogen type. Implications relative to the environment where the plants lived millions years ago are also given. Finally, the results highlight the constitution of one of the most important paleontological sites of the Cretaceous Period in the South America.

  7. A Case Study of Behaviour and Performance of Confined or Pastured Cows During the Dry Period

    PubMed Central

    Black, Randi A.; Krawczel, Peter D.

    2016-01-01

    Simple Summary Pasture and freestall systems offer benefits and consequences during lactation but have not been investigated during the dry period. The effect of pasture or confined systems during the dry period on behaviour and milk quality was investigated. Freestall housing resulted in more resting behaviour and less locomotor activity during the dry period compared to pastured cows. At calving, freestall housed cows performed fewer lying bouts and less locomotor activity compared to pastured cows. Pasture resulted in less aggression around feeding but high respiration rates during peak heat times. Pasture during the dry period altered lying behavior, reduced feed bunk aggression and increased heat stress behaviors. Abstract The objectives of this study were to determine the effect of the dry cow management system (pasture or confined) on: (1) lying behaviour and activity; (2) feeding and heat stress behaviours; (3) intramammary infections, postpartum. Non-lactating Holstein cows were assigned to either deep-bedded, sand freestalls (n = 14) or pasture (n = 14) using rolling enrollment. At dry-off, cows were equipped with an accelerometer to determine daily lying time (h/d), lying bouts (bouts/d), steps (steps/d) and divided into periods: far-off (60 to 15 d prepartum), close-up (14 to 1 d prepartum), calving (calving date) and postpartum (1 to 14 d postpartum). Respiration rates were recorded once weekly from dry off to calving from 1300 to 1500 h. Feeding displacements were defined as one cow successfully displacing another from the feed bunk and were recorded once per week during the 2 h period, immediately after feeding at 800 h. Pastured cows were fed a commercial dry cow pellet during far-off and total mixed ration during close-up, with free access to hay and grazing. Freestall housed cows were fed a total mixed ration at far-off and close-up. Cows housed in freestalls were moved to a maternity pen with a mattress at commencement of labour. Pastured cows

  8. Numerical study of deformation-induced fluid flows in periodic osteonal matrix under harmonic axial loading

    NASA Astrophysics Data System (ADS)

    Nguyen, Vu-Hieu; Lemaire, Thibault; Naili, Salah

    2009-05-01

    Living bone is a tissue that is constantly renewed. It has been demonstrated that bone fluid flow and induced shear effects on the bone cells are important players in triggering and signaling bone formation and remodelling. This Note presents a model studying interstitial fluid flow in cortical bone under axial harmonic loads. These living tissues are considered as saturated anisotropic poroelastic material characterized by three-dimensional periodic groups of osteons. Using a frequency-domain analysis, the fluid shear stress variations are studied for various loading conditions and geometrical or physical bone matrix parameters. To cite this article: V.-H. Nguyen et al., C. R. Mecanique 337 (2009).

  9. Cascade synthesis of polyoxygenated 6H,11H-[2]benzopyrano-[4,3-c][1]benzopyran-11-ones.

    PubMed

    Naumov, Mikael I; Sutirin, Sergey A; Shavyrin, Andrey S; Ganina, Olga G; Beletskaya, Irina P; Bourgarel-Rey, Véronique; Combes, Sébastien; Finet, Jean-Pierre; Fedorov, Alexey Yu

    2007-04-27

    2-(methoxymethoxymethyl)aryllead triacetates, obtained in situ from the corresponding arylboronic acids, reacted with 4-hydroxycoumarins, leading to 3-(2-methoxymethoxymethyl)aryl-4-hydroxycoumarin derivatives in good to high yields. These compounds underwent a cascade sequence of reactions, deprotection-halogenation-annulation, to afford polyoxygenated tetracyclic 6H,11H-[2]benzopyrano-[4,3-c] [1]benzopyran-11-ones in good yields. Some compounds showed a moderate cytotoxicity against human epithelial mammary HBL100 cells.

  10. Critical periods after stroke study: translating animal stroke recovery experiments into a clinical trial

    PubMed Central

    Dromerick, Alexander W.; Edwardson, Matthew A.; Edwards, Dorothy F.; Giannetti, Margot L.; Barth, Jessica; Brady, Kathaleen P.; Chan, Evan; Tan, Ming T.; Tamboli, Irfan; Chia, Ruth; Orquiza, Michael; Padilla, Robert M.; Cheema, Amrita K.; Mapstone, Mark E.; Fiandaca, Massimo S.; Federoff, Howard J.; Newport, Elissa L.

    2015-01-01

    Introduction: Seven hundred ninety-five thousand Americans will have a stroke this year, and half will have a chronic hemiparesis. Substantial animal literature suggests that the mammalian brain has much potential to recover from acute injury using mechanisms of neuroplasticity, and that these mechanisms can be accessed using training paradigms and neurotransmitter manipulation. However, most of these findings have not been tested or confirmed in the rehabilitation setting, in large part because of the challenges in translating a conceptually straightforward laboratory experiment into a meaningful and rigorous clinical trial in humans. Through presentation of methods for a Phase II trial, we discuss these issues and describe our approach. Methods: In rodents there is compelling evidence for timing effects in rehabilitation; motor training delivered at certain times after stroke may be more effective than the same training delivered earlier or later, suggesting that there is a critical or sensitive period for strongest rehabilitation training effects. If analogous critical/sensitive periods can be identified after human stroke, then existing clinical resources can be better utilized to promote recovery. The Critical Periods after Stroke Study (CPASS) is a phase II randomized, controlled trial designed to explore whether such a sensitive period exists. We will randomize 64 persons to receive an additional 20 h of upper extremity therapy either immediately upon rehab admission, 2–3 months after stroke onset, 6 months after onset, or to an observation-only control group. The primary outcome measure will be the Action Research Arm Test (ARAT) at 1 year. Blood will be drawn at up to 3 time points for later biomarker studies. Conclusion: CPASS is an example of the translation of rodent motor recovery experiments into the clinical setting; data obtained from this single site randomized controlled trial will be used to finalize the design of a Phase III trial. PMID

  11. Evidence from Broadband Rotational Spectroscopy for a Complex Between AgCCH and C6H6

    NASA Astrophysics Data System (ADS)

    Zaleski, Daniel P.; Stephens, Susanna Louise; Walker, Nick; Legon, Anthony

    2014-06-01

    Last year, at the 68th International Symposium of Molecular Spectroscopy, the rotational spectrum of a complex formed between C2H2 and AgCCH was presented. The geometry was found to be T-shaped with the silver atom coordinated to the center of the CC bond in acetylene. Evidence for a new complex formed between AgCCH and C6H6 is now presented in the form of deep-averaged broadband rotational spectra. The spectra are observed only when both C2H2 and C6H6 are present in the gas sample. The relative intensities of the observed spectra are consistent with the naturally-occurring abundance ratio of the isotopes of silver. The shift on substitution of 107Ag for 109Ag implies a silver atom positioned close to the center of mass. The isotopic shifts observed when C2D2 is used as a precursor instead of C2H2 are also consistent with assignment to a complex formed between C6H6 and AgCCH/D. The geometry of the complex is yet to be precisely established.

  12. Joint HVDC Agricultural Study : Annual Progress Report for the 1985 Study Period.

    SciTech Connect

    Raleigh, Robert J.

    1986-02-01

    This report describes the first year of a 3-year study designed to assess the possible environmental effects of a +-500-kV dc transmission line. This first annual report documents site development, initiation of the livestock and crop studies, and the integration and interfacing of the agricultural and BPA's electrical monitoring study. The overall objective is to assess whether operation of a +-500-kV dc transmission line results in any detectable effects (beneficial or adverse) on plants or livestock, under controlled, simulated farming and ranching conditions. These two biological systems were selected because they can be expected to experience long-term exposure to maximum field and ion concentrations on the transmission right-of-way. This study is designed to provide data on end points and parameters of primary interest in commercial farming and ranching operations.

  13. Short communication: study of immune parameters in three Greek dairy sheep breeds during the periparturient period.

    PubMed

    Theodorou, G; Fragou, S; Chronopoulou, R; Kominakis, A; Rogdakis, E; Politis, I

    2007-12-01

    The objective of the present study was to evaluate whether immunosuppression occurs in 3 different Greek dairy sheep breeds during the periparturient period. A total of 33 ewes from 3 breeds [i.e., the low-producing Boutsiko breed (n = 11), which is highly adaptable to harsh environments; the high-producing but environmentally fragile Chios breed (n = 11); and an intermediate synthetic breed (50% Boutsiko, 25% Arta, and 25% Chios, n = 11)] were used. Blood samples were collected at 18 and 2 d before parturition and at 15 d after parturition. Total cell-associated and membrane-bound urokinase plasminogen activator (U-PA) activity, free U-PA binding sites on cellular membranes, and superoxide anion (SA) production by activated phagocytes were determined. Results indicated that all immune parameters measured remained constant during the periparturient period for the Boutsiko breed. In contrast, there were reductions in total cell-associated and membrane-bound U-PA activity by both monocytes-macrophages and neutrophils and in SA production by monocytes-macrophages at d 2 before parturition for the Chios breed. In the synthetic breed, there were reductions in total cell-associated and membrane-bound U-PA activity by monocytes-macrophages and in SA production by both monocytes-macrophages and neutrophils at d 15 after parturition. Thus, mild immunosuppression during the periparturient period was observed in the 2 breeds with the highest milk production.

  14. On Flowfield Periodicity in the NASA Transonic Flutter Cascade. Part 2; Numerical Study

    NASA Technical Reports Server (NTRS)

    Chima, Rodrick V.; McFarland, Eric R.; Wood, Jerry R.; Lepicovsky, Jan

    2000-01-01

    The transonic flutter cascade facility at NASA Glenn Research Center was redesigned based on a combined program of experimental measurements and numerical analyses. The objectives of the redesign were to improve the periodicity of the cascade in steady operation, and to better quantify the inlet and exit flow conditions needed for CFD predictions. Part I of this paper describes the experimental measurements, which included static pressure measurements on the blade and endwalls made using both static taps and pressure sensitive paints, cobra probe measurements of the endwall boundary layers and blade wakes, and shadowgraphs of the wave structure. Part II of this paper describes three CFD codes used to analyze the facility, including a multibody panel code, a quasi-three-dimensional viscous code, and a fully three-dimensional viscous code. The measurements and analyses both showed that the operation of the cascade was heavily dependent on the configuration of the sidewalls. Four configurations of the sidewalls were studied and the results are described. For the final configuration, the quasi-three-dimensional viscous code was used to predict the location of mid-passage streamlines for a perfectly periodic cascade. By arranging the tunnel sidewalls to approximate these streamlines, sidewall interference was minimized and excellent periodicity was obtained.

  15. A comparative study of stress episode prevalence and duration among Jomon period foragers from Hokkaido.

    PubMed

    Temple, Daniel H; McGroarty, Jennifer N; Guatelli-Steinberg, Debbie; Nakatsukasa, Masato; Matsumura, Hirofumi

    2013-10-01

    This study reconstructs linear enamel hypoplasia (LEH) prevalence and stress episode duration among Jomon period foragers from Hokkaido, Japan (HKJ). Results are compared to Jomon period samples from coastal Honshu, Japan (HSJ) and Tigara Inupiat from Point Hope, Alaska (PHT) to provide a more comprehensive perspective on the manifestation of stress among circum-Pacific foragers. LEH were identified macro- and microscopically by enamel surface depressions and increased perikymata spacing within defects. Individuals with more than one anterior tooth affected by LEH were labeled as LEH positive. Stress episode durations were estimated by counting the number of perikymata within the occlusal wall of each LEH and multiplying that number by constants reflecting modal periodicities for modern human teeth. LEH prevalence and stress episode duration did not differ significantly between the two Jomon samples. Significantly greater frequencies of LEH were found in HKJ as compared to PHT foragers. However, HKJ foragers had significantly shorter stress episode durations as compared to PHT. This suggests that a greater proportion of HKJ individuals experienced stress episodes than did PHT individuals, but these stress events ended sooner. Similarity in stress experiences between the two Jomon samples and differences between the HKJ and PHT are found. These findings are important for two reasons. First, stress experiences of foraging populations differ markedly and cannot be generalized by subsistence strategy alone. Second, due to significant differences in episode duration, stress experiences cannot be understood using prevalence comparisons alone.

  16. Should Age-Period-Cohort Studies Return to the Methodologies of the 1970s?

    PubMed Central

    Masters, Ryan K.; Yang, Y. Claire; Powers, Daniel A.; Zheng, Hui; Land, Kenneth C.

    2015-01-01

    Social scientists have recognized the importance of age-period-cohort (APC) models for half a century, but have spent much of this time mired in debates about the feasibility of APC methods. Recently, a new class of APC methods based on modern statistical knowledge has emerged, offering potential solutions. In 2009, Reither, Hauser and Yang used one of these new methods – hierarchical APC (HAPC) modeling – to study how birth cohorts may have contributed to the U.S. obesity epidemic. They found that recent birth cohorts experience higher odds of obesity than their predecessors, but that ubiquitous period-based changes are primarily responsible for the rising prevalence of obesity. Although these findings have been replicated elsewhere, recent commentaries by Bell and Jones call them into question – along with the new class of APC methods. Specifically, Bell and Jones claim that new APC methods do not adequately address model identification and suggest that “solid theory” is often sufficient to remove one of the three temporal dimensions from empirical consideration. They also present a series of simulation models that purportedly show how the HAPC models estimated by Reither et al. (2009) could have produced misleading results. However, these simulation models rest on assumptions that there were no period effects, and associations between period and cohort variables and the outcome were perfectly linear. Those are conditions under which APC models should never be used. Under more tenable assumptions, our own simulations show that HAPC methods perform well, both in recovering the main findings presented by Reither et al. (2009) and the results reported by Bell and Jones. We also respond to critiques about model identification and theoretically-imposed constraints, finding little pragmatic support for such arguments. We conclude by encouraging social scientists to move beyond the debates of the 1970s and toward a deeper appreciation for modern APC

  17. Synthesis, crystal structure and characterization of a new organic-inorganic hybrid material: [C6H16N2O]SbCl5

    NASA Astrophysics Data System (ADS)

    Aloui, Z.; Ferretti, V.; Abid, S.; Rzaigui, M.; Lefebvre, F.; Ben Nasr, C.

    2015-05-01

    The present paper undertakes the study of [C6H16N2O]SbCl5 which is a new hybrid compound. It is synthesized and characterized by single-crystal X-ray diffraction, thermal analysis, IR and solid state NMR spectroscopies. The centrosymmetric compound crystallizes in the monoclinic space group P21/n, with the following unit cell parameters: a = 9.8519(2), b = 8.8345(2), c = 17.3087(4) Å, β = 102.3(1)° and Z = 4. The atomic arrangement shows an alternation of organic and inorganic entities. The cohesion between these entities is performed via N-H⋯Cl and O-H⋯Cl hydrogen bonding to form a three-dimensional network. The 13C CP-MAS NMR spectrum is in agreement with the X-ray structure. Infrared and Raman spectra at room temperature are recorded in the 4000-400 and 500-100 cm-1 frequency regions respectively. This study confirms the presence of the organic cation [C6H16N2]2+ and of the [SbCl5]2- anion. DFT calculations allow the attribution of the carbon peaks to the different atoms.

  18. DMFT Study for Valence Fluctuations in the Extended Periodic Anderson Model

    NASA Astrophysics Data System (ADS)

    Shinzaki, Ryu; Nasu, Joji; Koga, Akihisa

    2016-02-01

    We study valence fluctuations at finite temperatures in the extended periodic Anderson model, where the Coulomb interaction between conduction and localized f-electrons is taken into account, using dynamical mean-field theory combined with the continuous-time quantum Monte Carlo (CT-QMC) method. The valence transition with the hysteresis is clearly found, indicating the first-order phase transition between the Kondo and mixed-valence states. We demonstrate that spin correlation rapidly develops when the system approaches the valence transition point. The comparison of the impurity solvers, the CT-QMC, non-crossing approximation, and one-crossing approximation, is also addressed.

  19. Total cross sections of electron scattering by C4H8O, C5H10O2, C6H5F, C6H5Cl, C6F5Cl, C6H4(CHO)F and C4H8O2 at 30-5000 eV

    NASA Astrophysics Data System (ADS)

    Shi, D. H.; Liu, Y. F.; Ma, H.; Yu, B. H.; Sun, J. F.; Zhu, Z. L.

    2008-08-01

    Total cross sections for electron scattering by large molecules C4H8O, C5H10O2, C6H5F, C6H5Cl, C6F5Cl, C6H4(CHO)F and C4H8O2 are calculated at the Hartree-Fork level using the modified additivity rule approach. The modified additivity rule approach, which was proposed by Shi et al. [Eur. Phys. J. D 45, 253 (2007); Nucl. Instrum. Meth. B 254, 205 (2007)], takes into consideration that the contributions of the geometric shielding effect vary with the energy of the incident electrons, the target’s molecular dimension and the atomic and electronic numbers of the molecule. The present calculations cover the collision energies ranging from 30 to 5000 eV. The quantitative total cross sections are compared with those obtained by experiments and other theories. Good agreement is obtained even at energies of several tens of eV. It shows that the modified additivity rule approach is applicable to calculate the total cross sections of electron scattering by so large molecules at intermediate and high energies, especially above 100 eV. The total cross sections for electron scattering by the C4H8O2 molecule are predicted although no experimental and theoretical data are available for comparison over the present energy region.

  20. Analytical Study of Periodic Solutions on Perturbed Equatorial Two-Body Problem

    NASA Astrophysics Data System (ADS)

    Abouelmagd, Elbaz I.; Mortari, Daniele; Selim, Hadia H.

    2015-12-01

    This paper presents analytical derivations to study periodic solutions for the two-body problem perturbed by the first zonal harmonic parameter. In particular, three different semianalytical approaches to solve this problem have been studied: (1) the classic perturbation theory, (2) the Lindstedt-Poincaré technique, and (3) the Krylov-Bogoliubov-Mitropolsky method. In addition, the numerical integration by Runge-Kutta algorithm is established. However, the numerical comparison tests show that by increasing the value of angular momentum the solutions provided by Lindstedt-Poincaré and Krylov-Bogoliubov-Mitropolsky methods become similar, and they provide almost identical results using a smaller value for the perturbed parameter which quantify the dynamical flattening of the main body, the Krylov-Bogoliubov-Mitropolsky provides more accurate results to design elliptical periodic solutions than Lindstedt-Poincaré technique when the perturbed parameter has a relatively large value, regardless of the value of angular momentum. This study can be applied to equatorial orbits to obtain closed-form analytical solutions.

  1. Studies of FCAPT uvby Photometry of mCP Stars with Period04

    NASA Astrophysics Data System (ADS)

    Adelman, Saul Joseph; Jones Dukes, Robert

    2015-08-01

    We present differential Stromgren uvby observations of a few magnetic Chemically Peculiar (mCP) Stars from the Four College Automated Photometric Telescope to illustrate some interesting results found using Period04. Without an observer monitoring the weather, quality control depends on a several part process of closely inspecting the data. For each star we found a preliminary rotation period from the periodograms of the 4 filters and then used the accompanying non-linear least square tool to refine it. Next we repeated the analysis on the residuals from the fit to determine other periods. Usually we found the higher harmonics for those stars with non-sinusoidal light curves. In at least two cases there were low frequency terms.These high quality datasets usually have a greater number of yearly values obtained over more observing seasons than published studies. Stromgren intermediate bandwidth filters have mean wavelengths of λ3500 for u, λ4410 for v, λ4650 for b, and λ5470 for y with halfwidths of 300, 190, 180, and 230 Angstroms, respectively. The v and y values are often affected by broad, continuum features centered near λ4200 and λ5200.The mCP stars have non-aligned rotation and magnetic axes with emergent energy distributions, abundances, and magnetic field strengths being functions of photospheric position. Most have dipolar magnetic fields. Hydrodynamical processes, including radiative diffusion and gravitational settling, act in the radiative envelope to modify the elemental abundances relative to solar values. When such a star rotates, a distant observer often can see photometric, spectrum, and/or magnetic variability. Detecting one of these types of variability for a star with a mCP spectral classification means that it also varies in the other two ways which may not be easy to detect.Some particularly interesting results includeHD 5797 whose v variation is unique in having both the smallest amplitude and an apparent period one-half the period

  2. Experimental Study of the Effects of Periodic Unsteady Wakes on Flow Separation in Low Pressure Turbines

    NASA Technical Reports Server (NTRS)

    Ozturk, Burak; Schobeiri, Meinhard T.

    2009-01-01

    The present study, which is the first of a series of investigations of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary layer flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed on a large-scale, high-subsonic unsteady turbine cascade research facility with an integrated wake generator and test section unit. Blade Pak B geometry was used in the cascade. The wakes were generated by continuously moving cylindrical bars device. Boundary layer investigations were performed using hot wire anemometry at Reynolds number of 110,000, based on the blade suction surface length and the exit velocity, for one steady and two unsteady inlet flow conditions, with the corresponding passing frequencies, wake velocities, and turbulence intensities. The reduced frequencies cover the entire operation range of LP-turbines. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re = 50,000, 75,000, 100,000, 110,000, and 125,000. For each Reynolds number, surface pressure measurements are carried out at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extension of the separation zone as well as its behavior under unsteady wake flow. The results, presented in ensemble-averaged and contour plot forms, help to understand the physics of the separation phenomenon under periodic unsteady wake flow.

  3. Case study: Nutrition and training periodization in three elite marathon runners.

    PubMed

    Stellingwerf, Trent

    2012-10-01

    Laboratory-based studies demonstrate that fueling (carbohydrate; CHO) and fluid strategies can enhance training adaptations and race-day performance in endurance athletes. Thus, the aim of this case study was to characterize several periodized training and nutrition approaches leading to individualized race-day fluid and fueling plans for 3 elite male marathoners. The athletes kept detailed training logs on training volume, pace, and subjective ratings of perceived exertion (RPE) for each training session over 16 wk before race day. Training impulse/load calculations (TRIMP; min × RPE = load [arbitrary units; AU]) and 2 central nutritional techniques were implemented: periodic low-CHO-availability training and individualized CHO- and fluid-intake assessments. Athletes averaged ~13 training sessions per week for a total average training volume of 182 km/wk and peak volume of 231 km/wk. Weekly TRIMP peaked at 4,437 AU (Wk 9), with a low of 1,887 AU (Wk 16) and an average of 3,082 ± 646 AU. Of the 606 total training sessions, ~74%, 11%, and 15% were completed at an intensity in Zone 1 (very easy to somewhat hard), Zone 2 (at lactate threshold) and Zone 3 (very hard to maximal), respectively. There were 2.5 ± 2.3 low-CHO-availability training bouts per week. On race day athletes consumed 61 ± 15 g CHO in 604 ± 156 ml/hr (10.1% ± 0.3% CHO solution) in the following format: ~15 g CHO in ~150 ml every ~15 min of racing. Their resultant marathon times were 2:11:23, 2:12:39 (both personal bests), and 2:16:17 (a marathon debut). Taken together, these periodized training and nutrition approaches were successfully applied to elite marathoners in training and competition.

  4. Bulk Micromachined 6H-SiC High-g Piezoresistive Accelerometer Fabricated and Tested

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.

    2002-01-01

    High-g accelerometers are needed in certain applications, such as in the study and analysis of high-g impact landings and projectiles. Also, these accelerometers must survive the high electromagnetic fields associated with the all-electric vehicle technology needed for aerospace applications. The choice of SiC is largely due to its excellent thermomechanical properties over conventional silicon-based accelerometers, whose material properties inhibit applicability in high electromagnetic radiation and high temperatures (>150 C) unless more complex and sometimes costly packaging schemes are adopted. This work was the outcome of a NASA Glenn Research Center summer internship program, in collaboration with Cornell University and the Munitions Directorate of the U.S. Air Force in Eglin, Florida. It aimed to provide the enabling technology infrastructure (modeling, fabrication, and validation) for the implementation of SiC accelerometers designed specifically for harsh environments.

  5. Structural features of small benzene clusters (C6H6)n (n ≤ 30) as investigated with the all-atom OPLS potential.

    PubMed

    Takeuchi, Hiroshi

    2012-10-18

    The structures of the simplest aromatic clusters, benzene clusters (C(6)H(6))(n), are not well elucidated. In the present study, benzene clusters (C(6)H(6))(n) (n ≤ 30) were investigated with the all-atom optimized parameters for liquid simulation (OPLS) potential. The global minima and low-lying minima of the benzene clusters were searched with the heuristic method combined with geometrical perturbations. The structural features and growth sequence of the clusters were examined by carrying out local structure analyses and structural similarity evaluation with rotational constants. Because of the anisotropic interaction between the benzene molecules, the local structures consisting of 13 molecules are considerably deviated from regular icosahedron, and the geometries of some of the clusters are inconsistent with the shapes constructed by the interior molecules. The distribution of the angle between the lines normal to two neighboring benzene rings is anisotropic in the clusters, whereas that in the liquid benzene is nearly isotropic. The geometries and energies of the low-lying configurations and the saddle points between them suggest that most of the configurations previously detected in supersonic expansions take different orientations for one to four neighboring molecules.

  6. Markers of glycemic control in the mouse: comparisons of 6-h- and overnight-fasted blood glucoses to Hb A1c.

    PubMed

    Han, Byoung Geun; Hao, Chuan-Ming; Tchekneva, Elena E; Wang, Ying-Ying; Lee, Chieh Allen; Ebrahim, Benyamin; Harris, Raymond C; Kern, Timothy S; Wasserman, David H; Breyer, Matthew D; Qi, Zhonghua

    2008-10-01

    The present studies examined the relationship between fasting blood glucose and Hb A(1c) in C57BL/6J, DBA/2J, and KK/HlJ mice with and without diabetes mellitus. Daily averaged blood glucose levels based on continuous glucose monitoring and effects of 6-h vs. overnight fasting on blood glucose were determined. Daily averaged blood glucose levels were highly correlated with Hb A(1c), as determined with a hand-held automated device using an immunodetection method. R(2) values were 0.90, 0.95, and 0.99 in KK/HIJ, C57BL/6J, and DBA/2J, respectively. Six-hour fasting blood glucose correlated more closely with the level of daily averaged blood glucose and with Hb A(1c) than did blood glucose following an overnight fast. To validate the immunoassay-determined Hb A(1c), we also measured total glycosylated hemoglobin using boronate HPLC. Hb A(1c) values correlated well with total glycosylated hemoglobin in all three strains but were relatively lower than total glycosylated hemoglobin in diabetic DBA/2J mice. These results show that 6-h fasting glucose provides a superior index of glycemic control and correlates more closely with Hb A(1c) than overnight-fasted blood glucose in these strains of mice.

  7. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

    SciTech Connect

    J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi

    2006-04-01

    The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.

  8. Study on the Period of the Use of Datong-li in Korea

    NASA Astrophysics Data System (ADS)

    Lee, Ki-Won; Ahn, Young-Sook; Mihn, Byeong-Hee; Lim, Young-Ryan

    2010-03-01

    It has been generally known that Datong-li (a Chinese calendar in the Ming dynasty)was first introduced into Korea in the nineteenth reign of King Gongmin (1370) of the Goryeo dynasty and lasted to the third reign of King Hyeojong (1652) of the Joseon dynasty. This understanding is based on the records of Goryeo-sa (History of the Goryeo dynasty) and of Seoungwan-ji (Official book of Seoungwan)/ Jeungbomunheon bigo (Explanatory Notes of Library ocument). To verify the period of the use of Datong-li in Korea, we develop a Fortran code to calculate the calendar day by Datong-li and also investigate historical literatures and extant almanacs. As a result, we find the possibility that Datong-li had been in use since 1389 at least. However,we cannot confirm whether Datong-li was first enforced in 1370 or not. On the other hand, we confirm that Datong-li was used until 1653 and reintroduced during the period from 1667 to 1669. Also, we find that previous studies had some errors in the sexagenary cycle of the real first day of a month. We think that this study will contribute to understanding the calendrical history of the Joseon dynasty.

  9. Emergence periodicity of Phlebotomus argentipes annandale and brunetti (Diptera: psychodidae): A laboratory study.

    PubMed

    Dinesh, D S; Singh, A; Kumar, V; Kesari, S; Kumar, A J; Kishore, K; Roy, S P; Bhattacharya, S K; Das, P

    2009-12-01

    Phlebotomus argentipes Annandale and Brunetti (Diptera: Psychodidae) is the vector for visceral leishmaniasis in India. The aspects of its biology such as feeding and man vector contact are associated with emergence periodicity of the adult. Hence, the present study was made to find out the actual emergence period of P. argentipes. Wild caught P. argentipes were confined in the rearing pots inside laboratory. The newly emerged adults were collected at hourly intervals and released in to separate polythene bags and were held at 4°C till death. Sand flies were segregated sex-wise after the death under a microscope. The emergence of adult was observed throughout the day. However, the male preferred dawn emergence and the female the dusk. Two peaks of emergence were found in a day; first one in the morning (0900h) and the second one in the evening (1800h). The ratio of both sexes was found to be about equal. The emergence of adult was found to be 77% out of total eggs laid, which was completed within 7-10 days from the 1st day of emergence under laboratory conditions (25°C to 31°C and 70% to 75% relative humidity). This study has important bearings to find out the actual time for personal protection against biting of sand flies to prevent the transmission of Kala-azar.

  10. A Study on Effects of Waiting Period in Software Operation on the Operator's Psychophysiological State

    NASA Astrophysics Data System (ADS)

    Hayasaka, Yoshiaki; Kimura, Tatsuhiro; Segawa, Norihisa; Miyazaki, Masatoshi; Yamazaki, Kiyoyuki; Murayama, Yuko

    The authors have been studying psychophysiological workload of human interface (HI) with physiological measurements and analysis. In this study, we investigated a kind of mental workload produced by user's unexpected waiting period from the request input to the termination of data processing during personal computer (PC) operation. As the experimental setting of HI, we used interactive software containing easy questions with unexpected time interval between each question. The effects of progress indicator (PI) indicating during waiting period on psychophysiological status of users were analyzed by using respiration, finger plethysmogram (PTG), heart rate (HR) and electroencephalogram (EEG) measurements. Results showed that the theta wave component of the EEG increased in the non-PI condition, even though autonomic nervous system parameters showed no significant change. Negative correlation between preference score for HI and integrated theta component percentage was observed only in non-PI condition. It is supposed that the PI was controlling theta activity coused by waiting stress in experimental condition. Utilizing physiological indices for HI assessment, this experimental method could be available to waiting stress estimation.

  11. Study of deformed quasi-periodic Fibonacci two dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Ben Abdelaziz, K.; Bouazzi, Y.; Kanzari, M.

    2015-09-01

    Quasi-periodic photonic crystals are not periodic structures. These structures are generally obtained by the arrangement of layers according to a recursive rule. Properties of these structures make more attention the researchers especially in the case when applying defects. So, photonic crystals with defects present localized modes in the band gap leading to many potential applications such light localization. The objective of this work is to study by simulation the effect of the global deformation introduced in 2D quasiperiodic photonic crystals. Deformation was introduced by applying a power law, so that the coordinates y of the deformed object were determined through the coordinates x of the non-deformed structure in accordance with the following rule: y = x1+k. Here k is the coefficient defining the deformation. Therefore, the objective is to study the effect of this deformation on the optical properties of 2D quasiperiodic photonic crystals, constructed by Fibonacci generation. An omnidirectional mirror was obtained for optimization Fibonacci iteration in a part of visible spectra.

  12. Electronic and Interfacial Properties of PD/6H-SiC Schottky Diode Gas Sensors

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Bansal, Gaurav; Petit, Jeremy B.; Knight, Dak; Liu, Chung-Chiun; Wu, Qinghai

    1996-01-01

    Pd/SiC Schottky diodes detect hydrogen and hydrocarbons with high sensitivity. Variation of the diode temperature from 100 C to 200 C shows that the diode sensitivity to propylene is temperature dependent. Long-term heat treating at 425 C up to 140 hours is carried out to determine the effect of extended heat treating on the diode properties and gas sensitivity. The heat treating significantly affects the diode's capacitive characteristics, but the diode's current carrying characteristics are much more stable with a large response to hydrogen. Scanning Electron Microscopy and X-ray Spectrometry studies of the Pd surface after the heating show cluster formation and background regions with grain structure observed in both regions. The Pd and Si concentrations vary between grains. Auger Electron Spectroscopy depth profiles revealed that the heat treating promoted interdiffusion and reaction between the Pd and SiC dw broadened the interface region. This work shows that Pd/SiC Schottky diodes have significant potential as high temperature gas sensors, but stabilization of the structure is necessary to insure their repeatability in long-term, high temperature applications.

  13. Phyllanthus muellerianus and C6H15NO3 synergistic effects on 0.5 M H2SO4-immersed steel-reinforced concrete: Implication for clean corrosion-protection of wind energy structures in industrial environment

    NASA Astrophysics Data System (ADS)

    Okeniyi, Joshua Olusegun; Omotosho, Olugbenga Adeshola; Popoola, Abimbola Patricia Idowu; Loto, Cleophas Akintoye

    2016-07-01

    This paper investigates Phyllanthus muellerianus leaf-extract and C6H15NO3 (triethanolamine: TEA) synergistic effects on reinforcing-steel corrosion-inhibition and the compressive-strength of steel-reinforced concrete immersed in 0.5 M H2SO4. This is to assess suitability of the synergistic admixture usage for wind-energy steel-reinforced concrete structures designed for industrial environments. Steel-reinforced concrete specimens were admixed with individual and synergistic designs of Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures and immersed in the 0.5 M H2SO4. Electrochemical monitoring of corrosion potential, as per ASTM C876-91 R99, and corrosion current were obtained and statistically analysed, as per ASTM G16-95 R04, for modelling noise resistance. Post-immersion compressive-strength testing then followed, as per ASTM C39/C39M-03, for detailing the admixture effect on load-bearing strength of the steel-reinforced concrete specimens. Results showed that while individual Phyllanthus muellerianus leaf-extract concentrations exhibited better inhibition-efficiency performance than C6H15NO3, synergistic additions of C6H15NO3 to Phyllanthus muellerianus leaf-extract improved steel-rebar corrosion-inhibition. Thus, 6 g Phyllanthus muellerianus + 2 g C6H15NO3 synergistically improved inhibition-efficiency to η = 84.17%, from η = 55.28% by the optimal chemical or from η = 74.72% by the optimal plant-extract admixtures. The study also established that improved compressive strength of steel-reinforced concrete with acceptable inhibition of the steel-rebar corrosion could be attained through optimal combination of the Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures.

  14. Stern-Gerlach experiments of one-dimensional metal-benzene sandwich clusters: Mn(C6H6)m (M = Al, Sc, Ti, and V).

    PubMed

    Miyajima, Ken; Yabushita, Satoshi; Knickelbein, Mark B; Nakajima, Atsushi

    2007-07-11

    A molecular beam of multilayer metal-benzene organometallic clusters Mn(C6H6)m (M = Al, Sc, Ti, and V) was produced by a laser vaporization synthesis method, and their magnetic deflections were measured. Multidecker sandwich clusters of transition-metal atoms and benzene Scn(C6H6)n+1 (n = 1, 2) and Vn(C6H6)n+1 (n = 1-4) possess magnetic moments that increase monotonously with n. The magnetic moments of Al(C6H6), Scn(C6H6)n+1, and Vn(C6H6)n+1 are smaller than that of their spin-only values as a result of intracluster spin relaxation, an effect that depends on the orbital angular momenta and bonding characters of the orbitals containing electron spin. While Ti(C6H6)2 was found to be nonmagnetic, Tin(C6H6)n+1 (n = 2, 3) possess nonzero magnetic moments. The mechanism of ferromagnetic spin ordering in M2(C6H6)3 (M = Sc, Ti, V) is discussed qualitatively in terms of molecular orbital analysis. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition-metal atoms are formally zerovalent.

  15. Musculoskeletal symptoms and job strain among nursing personnel: a study over a three year period.

    PubMed Central

    Josephson, M; Lagerström, M; Hagberg, M; Wigaeus Hjelm, E

    1997-01-01

    OBJECTIVES: To examine the variation of symptoms from the neck, shoulders, and back over a three year period among female nursing personnel and the relation between job strain and musculoskeletal symptoms. METHODS: At a county hospital the female nursing personnel answered a questionnaire at baseline and then once a year over a period of three years. There were 565, 553, 562, and 419 subjects who answered the questionnaire at the first, second, third, and fourth survey, respectively. Of the study group, 285 nursing personnel answered the questionnaire on four occasions. Ongoing symptoms of the neck, shoulders, and back were assessed by means of a 10 point (0-9) scale with the verbal end points "no symptoms" and "very intense symptoms." Cases were defined as nursing personnel reporting ongoing symptoms, score > 6, from at least one of the body regions. For assessments of job strain, a Swedish version of Karasek and Theorell's model was used. RESULTS: Of the 285 subjects, 13% were defined as cases at all four assessments, and 46% varied between cases and not cases during the study period. In the repeated cross sectional surveys the estimated rate ratio (RR) for being a case was between 1.1 and 1.5 when comparing the group with job strain and the group without job strain. For the combination of job strain and perceived high physical exertion the estimated RR was between 1.5 and 2.1. When the potential risk factors were assessed one, two, or three years before the assessment of symptoms the estimated RR for becoming a case was between 1.4 and 2.2 when comparing the group with job strain and the group without job strain. CONCLUSION: Almost half of the healthcare workers varied between being a case and not, over a three year period. The analysis indicated that job strain is a risk factor for musculoskeletal symptoms and that the risk is higher when it is combined with perceived high physical exertion. PMID:9423583

  16. Synthesis, structural characterization, electrical properties and antioxidant activity of [p-(NH3)C6H4NH3]3P6O18·6H2O

    NASA Astrophysics Data System (ADS)

    Fezai, Ramzi; Mezni, Ali; Kahlaoui, Messaoud; Rzaigui, Mohamed

    2016-09-01

    Single crystals of a novel organic cyclohexaphosphate, [p-(NH3)C6H4NH3]3P6O18.6H2O, have been prepared in aqueous solution. Its crystal structure can be described by a three-dimensional framework where the P6O186- rings are interconnected by hydrogen bonds to form anionic layers between which organic cations are located. Hydrogen bonding network connecting the different components is given. The thermal stability and spectroscopic properties of this material are given too. Its DC and AC electrical conductivities, modulus analysis and dielectric constants have been investigated. The AC conductivity is found to obey the universal power law. The DC electrical conductivity indicates a semiconductor behavior. The kind of the observed conduction is protonic by translocation. X-rays structural and electrical results are correlated. This compound has also been screened for its antioxidant activity, determined in vitro, using 1,1-diphenyl-2-picrylhydrazyl, reducing power, hydroxyl scavenging ability and ferrous ion chelating (FIC) methods and with ascorbic acid as reference.

  17. Ultrafast time dynamics studies of periodic lattices with free electron laser radiation

    SciTech Connect

    Quevedo, W.; Busse, G.; Hallmann, J.; More, R.; Petri, M.; Rajkovic, I.; Krasniqi, F.; Rudenko, A.; Tschentscher, T.; Stojanovic, N.; Duesterer, S.; Treusch, R.; Tolkiehn, M.; Techert, S.

    2012-11-01

    It has been proposed that radiation from free electron laser (FEL) at Hamburg (FLASH) can be used for ultrafast time-resolved x-ray diffraction experiments based on the near-infrared (NIR) pump/FEL probe scheme. Here, investigation probing the ultrafast structural dynamics of periodic nano-crystalline organic matter (silver behenate) with such a scheme is reported. Excitation with a femtosecond NIR laser leads to an ultrafast lattice modification which time evolution has been studied through the scattering of vacuum ultraviolet FEL pulses. The found effect last for 6 ps and underpins the possibility for studying nanoperiodic dynamics down to the FEL source time resolution. Furthermore, the possibility of extending the use of silver behenate (AgBh) as a wavelength and temporal calibration tool for experiments with soft x-ray/FEL sources is suggested.

  18. A comprehensive study for the plasmonic thin-film solar cell with periodic structure.

    PubMed

    Sha, Wei E I; Choy, Wallace C H; Chew, Weng Cho

    2010-03-15

    A comprehensive study of the plasmonic thin-film solar cell with the periodic strip structure is presented in this paper. The finite-difference frequency-domain method is employed to discretize the inhomogeneous wave function for modeling the solar cell. In particular, the hybrid absorbing boundary condition and the one-sided difference scheme are adopted. The parameter extraction methods for the zeroth-order reflectance and the absorbed power density are also discussed, which is important for testing and optimizing the solar cell design. For the numerical results, the physics of the absorption peaks of the amorphous silicon thin-film solar cell are explained by electromagnetic theory; these peaks correspond to the waveguide mode, Floquet mode, surface plasmon resonance, and the constructively interference between adjacent metal strips. The work is therefore important for the theoretical study and optimized design of the plasmonic thin-film solar cell.

  19. An ab initio periodic study of acidic chabazite as a candidate for dihydrogen storage.

    PubMed

    Torres, F J; Civalleri, B; Pisani, C; Ugliengo, P

    2006-06-01

    A theoretical B3LYP study, adopting a polarized double-zeta quality Gaussian basis set, was performed to characterize acidic chabazite by using the periodic CRYSTAL03 program. Different Si/Al loadings (1/1, 3/1, 5/1, and 11/1) were considered, and for each of them the most stable aluminum distribution and location of the acidic proton, needed as charge balancer, were identified. With the optimal structures, the energy of formation and the anharmonic O-H stretching frequency were calculated with the latter being in good agreement with the experimental data. The B3LYP optimal position of H2 physisorbed at the acidic Brönsted sites of chabazite (Si/Al = 11/1 and 5/1) brings about an interaction energy definitely smaller than that derived from infrared spectroscopy, because of the known deficiencies of this functional to cope with dispersive interactions. The latter was included by means of an ONIOM-like procedure that combines periodic B3LYP energy with results at the MP2 level on selected clusters cut out of the chabazite framework. Adsorption of two H2 molecules for Si/Al = 5/1 chabazite showed a complete independence of each Brönsted site, and neither through-space nor intrastructure polarization effects are present. Within the periodic B3LYP approach shifts in both O-H and H-H anharmonic frequencies were also computed and compared with unperturbed values and with the available experimental results.

  20. Promoting scopolamine biosynthesis in transgenic Atropa belladonna plants with pmt and h6h overexpression under field conditions.

    PubMed

    Xia, Ke; Liu, Xiaoqiang; Zhang, Qiaozhuo; Qiang, Wei; Guo, Jianjun; Lan, Xiaozhong; Chen, Min; Liao, Zhihua

    2016-09-01

    Atropa belladonna is one of the most important plant sources for producing pharmaceutical tropane alkaloids (TAs). T1 progeny of transgenic A. belladonna, in which putrescine N-methyltransferase (EC. 2.1.1.53) from Nicotiana tabacum (NtPMT) and hyoscyamine 6β-hydroxylase (EC. 1.14.11.14) from Hyoscyamus niger (HnH6H) were overexpressed, were established to investigate TA biosynthesis and distribution in ripe fruits, leaves, stems, primary roots and secondary roots under field conditions. Both NtPMT and HnH6H were detected at the transcriptional level in transgenic plants, whereas they were not detected in wild-type plants. The transgenes did not influence the root-specific expression patterns of endogenous TA biosynthetic genes in A. belladonna. All four endogenous TA biosynthetic genes (AbPMT, AbTRI, AbCYP80F1 and AbH6H) had the highest/exclusive expression levels in secondary roots, suggesting that TAs were mainly synthesized in secondary roots. T1 progeny of transgenic A. belladonna showed an impressive scopolamine-rich chemotype that greatly improved the pharmaceutical value of A. belladonna. The higher efficiency of hyoscyamine conversion was found in aerial than in underground parts. In aerial parts of transgenic plants, hyoscyamine was totally converted to downstream alkaloids, especially scopolamine. Hyoscyamine, anisodamine and scopolamine were detected in underground parts, but scopolamine and anisodamine were more abundant than hyoscyamine. The exclusively higher levels of anisodamine in roots suggested that it might be difficult for its translocation from root to aerial organs. T1 progeny of transgenic A. belladonna, which produces scopolamine at very high levels (2.94-5.13 mg g(-1)) in field conditions, can provide more valuable plant materials for scopolamine production.

  1. Epidemiology of injuries in elite taekwondo athletes: two Olympic periods cross-sectional retrospective study

    PubMed Central

    Altarriba-Bartes, Albert; Drobnic, Franchek; Til, Lluís; Malliaropoulos, Nikolaos; Montoro, José Bruno; Irurtia, Alfredo

    2014-01-01

    Objective Taekwondo injuries differ according to the characteristics of the athletes and the competition. This analytical cross-sectional retrospective cohort study aimed to describe reported taekwondo injuries and to determine the prevalence, characteristics and possible risk factors for injuries sustained by athletes of the Spanish national team. In addition, we compared each identified risk factor—age, weight category, annual quarter, injury timing and competition difficulty level—with its relation to injury location and type. Settings Injury occurrences in taekwondo athletes of the Spanish national team during two Olympic periods at the High Performance Centre in Barcelona were analysed. Participants 48 taekwondo athletes (22 male, 26 female; age range 15–31 years) were studied; 1678 injury episodes occurred. Inclusion criteria were: (1) having trained with the national taekwondo group for a minimum of one sports season; (2) being a member of the Spanish national team. Results Independently of sex or Olympic period, the anatomical sites with most injury episodes were knee (21.3%), foot (17.0%), ankle (12.2%), thigh (11.4%) and lower leg (8.8%). Contusions (29.3%) and cartilage (17.6%) and joint (15.7%) injuries were the prevalent types of injury. Chronological age, weight category and annual quarter can be considered risk factors for sustaining injuries in male and female elite taekwondists according to their location and type (p≤0.001). Conclusions This study provides epidemiological information that will help to inform future injury surveillance studies and the development of prevention strategies and recommendations to reduce the number of injuries in taekwondo competition. PMID:24531455

  2. Comparative calculations of electron transport properties in 6H-SiC using three and five valley models

    NASA Astrophysics Data System (ADS)

    Talha, Nora; Bouazza, Benyounes; Guen Bouazza, Ahlam; Kadoun, Abd-Ed-Daim

    2016-07-01

    Steady-state electron properties are investigated in 6H-SiC at various temperatures, using Monte Carlo simulation where the band structure model is a major part when dealing with high fields. The aim of this work is to optimize the number of valleys involved in the simulation program in order to obtain accurate results while improving the calculation efficiency. For high fields, a five valley model was found to be more accurate than a three valley model and as efficient as the full band method though much less computer time-consuming.

  3. Sample size determination for alternate periods of use study designs with binary responses.

    PubMed

    Morel, Jorge G; Neerchal, Nagaraj K

    2012-01-01

    In this article, we consider several study designs that arise in practice, which are variations of standard crossover designs. Often, they may result from modifications made to a standard crossover design due to practical considerations. Characteristic features of the studies we are concerned with are (a) treatments consist of external use of products with little or no possibility of carry over effects, and (b) the periods of use are dictated by the subjects or by some specific event, such as diaper leakage or menstrual flow. We consider a number of such study designs for estimating the difference in the efficacy of two treatments or test products. We provide brief descriptions of studies to motivate the study design, the underlying data structure, and computations of the variances of the usual unbiased estimators of the difference in efficacy, and the sample size formulas. The situations considered here cover a number of popular crossover designs. The objective of our work is to provide guidance to members of a wide audience on how to answer the sample size question for their own nonstandard situations. We conclude the article with a brief report on a simulation study we conducted to investigate the impact of estimation on the sample size determination and consequently on the actual power realized in an effort to promote the "best practice" of checking whether the recommended sample sizes indeed achieve the desired level of power.

  4. Detection of (in)activity periods in human body motion using inertial sensors: a comparative study.

    PubMed

    Olivares, Alberto; Ramírez, Javier; Górriz, Juan M; Olivares, Gonzalo; Damas, Miguel

    2012-01-01

    Determination of (in)activity periods when monitoring human body motion is a mandatory preprocessing step in all human inertial navigation and position analysis applications. Distinction of (in)activity needs to be established in order to allow the system to recompute the calibration parameters of the inertial sensors as well as the Zero Velocity Updates (ZUPT) of inertial navigation. The periodical recomputation of these parameters allows the application to maintain a constant degree of precision. This work presents a comparative study among different well known inertial magnitude-based detectors and proposes a new approach by applying spectrum-based detectors and memory-based detectors. A robust statistical comparison is carried out by the use of an accelerometer and angular rate signal synthesizer that mimics the output of accelerometers and gyroscopes when subjects are performing basic activities of daily life. Theoretical results are verified by testing the algorithms over signals gathered using an Inertial Measurement Unit (IMU). Detection accuracy rates of up to 97% are achieved.

  5. Study of electromagnetic wave scattering by periodic density irregularities in plasma

    SciTech Connect

    Lyle, R.; Kuo, S.P.; Huang, J.

    1995-12-31

    A quasi-particle approach is used to formulate wave propagation and scattering in a periodically structured plasma. The theory is then applied to study the effect of bottomside sinusoidal (BSS) irregularities on the propagation of beacon satellites signals through the ionosphere. In this approach, the radio wave is treated as a distribution of quasi-particles described by a Wigner distribution function governed by a transport equation. The irregularities providing the collisional effect are modeled as a two dimensional density modulation on a uniform background plasma. The present work generalizes the previous work by including the spectral bandwidth ({Delta}k/k) effect of the spatially periodic irregularities on the transionospheric signal propagation. The collision of quasi-particles with the irregularities modifies the quasi-particle distribution and give rise to the wave scattering phenomenon. The multiple scattering process is generally considered in this deterministic analysis of radio wave scattering off the ionospheric density irregularities. The analysis shows that this two dimensional density grating effectively modulates the intensity of the beacon satellite signals. This spatial modulation of the wave intensity is converted into time modulation due to the drift of the ionospheric irregularities, which then results in the scintillation of the beacon satellite signals.

  6. Detection of (In)activity Periods in Human Body Motion Using Inertial Sensors: A Comparative Study

    PubMed Central

    Olivares, Alberto; Ramírez, Javier; Górriz, Juan M.; Olivares, Gonzalo; Damas, Miguel

    2012-01-01

    Determination of (in)activity periods when monitoring human body motion is a mandatory preprocessing step in all human inertial navigation and position analysis applications. Distinction of (in)activity needs to be established in order to allow the system to recompute the calibration parameters of the inertial sensors as well as the Zero Velocity Updates (ZUPT) of inertial navigation. The periodical recomputation of these parameters allows the application to maintain a constant degree of precision. This work presents a comparative study among different well known inertial magnitude-based detectors and proposes a new approach by applying spectrum-based detectors and memory-based detectors. A robust statistical comparison is carried out by the use of an accelerometer and angular rate signal synthesizer that mimics the output of accelerometers and gyroscopes when subjects are performing basic activities of daily life. Theoretical results are verified by testing the algorithms over signals gathered using an Inertial Measurement Unit (IMU). Detection accuracy rates of up to 97% are achieved. PMID:22778613

  7. A critical period of brain development: studies of cerebral glucose utilization with PET.

    PubMed

    Chugani, H T

    1998-01-01

    Studies with positron emission tomography indicate that the human brain undergoes a period of postnatal maturation that is much more protracted than previously suspected. In the newborn, the highest degree of glucose metabolism (representative of functional activity) is in primary sensory and motor cortex, cingulate cortex, thalamus, brain stem, cerebellar vermis, and hippocampal region. At 2 to 3 months of age, glucose utilization increases in the parietal, temporal, and primary visual cortex; basal ganglia; and cerebellar hemispheres. Between 6 and 12 months, glucose utilization increases in frontal cortex. These metabolic changes correspond to the emergence of various behaviors during the first year of life. The measurement of absolute rates of glucose utilization during development indicates that the cerebral cortex undergoes a dynamic course of metabolic maturation that persists until ages 16-18 years. Initially, there is a rise in the rates of glucose utilization from birth until about age 4 years, at which time the child's cerebral cortex uses over twice as much glucose as that of adults. From age 4 to 10 years, these very high rates of glucose consumption are maintained, and only after then is there a gradual decline of glucose metabolic rates to reach adult values by age 16-18 years. Correlations between glucose utilization rates and synaptogenesis are discussed, and the argument is made that these findings have important implications with respect to human brain plasticity following injury as well as to "critical periods" of maximal learning capacity.

  8. Nationwide study of childhood celiac disease incidence over a 35-year period in Estonia.

    PubMed

    Ress, Krista; Luts, Katrin; Rägo, Tiina; Pisarev, Heti; Uibo, Oivi

    2012-12-01

    The aims of the study were to analyze the trends and characteristics of the incidence and clinical presentation of childhood celiac disease (CD) from 1976 to 2010 in Estonia. The study included all children up to 19 years of age diagnosed with small bowel biopsy proven CD. During a 35-year period, CD was diagnosed in 152 children in Estonia (68 boys, median age 2.3 years). From 1976 to 1980, the age-standardized incidence rate of CD was 0.10 per 100,000 person-years. After the introduction of gliadin and endomysium antibody screening (in conjunction with activities directed to increase the physicians awareness), the incidence rate increased from 0.48 in 1986-1990 to 1.55 per 100,000 person-years in 1991-1995. After initiating screening with anti-tissue transglutaminase antibodies in 2003 and routine screening for CD among all children with newly diagnosed type 1 diabetes in 2005, the incidence rate increased from 1.59 in 2001-2005 to 3.14 per 100,000 person-years in 2006-2010 (median age 6.8 years). Our nationwide study demonstrates a more than 30-fold increase in the incidence of childhood CD over a 35-year period in Estonia, along with changing patterns in the presentation of pediatric CD. In addition to the impact of use of novel CD screening methods, active search and rising of the awareness among doctors may have strongest effect. Both environmental and social factors could be also involved in the increase in CD incidence.

  9. Primary prevention in health care employees: a prospective intervention study with a 3-year training period.

    PubMed

    Löffler, Harald; Bruckner, Thomas; Diepgen, Thomas; Effendy, Isaak

    2006-04-01

    Irritant contact dermatitis is a mayor problem in health care employees. Because educational programs have shown convincing success in certain occupations (e.g. in hairdressers), this study investigates the effect of a special training program in health care trainees. 521 trainees from 14 nursing schools in Central Germany were randomly divided in 2 groups, (i) an intervention group with a regular teaching protocol regarding all aspects of primary prevention and (ii) a control group without any further teaching. Morphological changes of the hands, use of hand care creams and knowledge regarding skin care were evaluated regularly during their 3 years lasting training period (1999-2002). In the intervention group, we found at the end of the 3-year training period a significant better skin condition of the hands than in the control group: a 3-year prevalence of morphological skin changes of 66.7% versus 89.3%. The unteached trainees (control group) had an odds ratio (OR) of 4.8 [95% confidential interval (CI): 2.9-7.8] for developing any skin changes on the hands after 3 years. Besides the effect of the teaching, the history of hand dermatitis before the study start was an independent risk factor for development of further hand dermatitis [OR 1.9, 95% CI: 1.0-3.6). Age and sex showed no influence on the skin condition. Atopic constitution had an influence on the development of skin changes only at the evaluation after 18 month. The observed effect in the intervention group may best be explained by different behaviour of the trainees, e.g. the amount of hand washing was reduced, while procedure of hand disinfection remained unchanged compared with the control group. However, the amount of used skin care cream did not differ between the both groups. This study shows that primary prevention of skin disease by regularly teaching during the training period of medical employees can effectively reduce the risk of development of irritant skin changes of the hands. Therefore

  10. A Study of the Utilization Patterns of an Elementary School-Based Health Clinic over a 5-Year Period

    ERIC Educational Resources Information Center

    Johnson, Veda; Hutcherson, Valerie

    2006-01-01

    The purpose of this study was to determine the utilization pattern of an elementary school-based clinic over a 5-year period. It involved a retrospective analysis of computer-based data for all patient visits during this study period. Results revealed high clinic utilization with an average of over 5 encounters for all users each year. The most…

  11. [Cloning and expression of the key enzyme hyoscyamine 6 beta-hydroxylase gene (DaH6H) in scopolamine biosynthesis of Datura arborea].

    PubMed

    Qiang, Wei; Hou, Yan-ling; Li, Xiao; Xia, Ke; Liao, Zhi-hua

    2015-10-01

    Hyoscyamine 6 beta-hydroxylase (H6H) is the last rate-limiting enzyme directly catalyzing the formation of scopolamine in tropane alkaloids (TAs) biosynthesis pathway. It is the primary target gene in the genetic modification of TAs metabolic pathway. Full-length cDNA and gDNA sequences of a novel H6H gene were cloned from Datura arborea (DaH6H, GenBank accession numbers for cDNA and gDNA are KR006981 and KR006983, respectively). Nucleotide sequence analysis reveals an open reading frame of 1375 bp encoding 347 amino acids in the cDNA of DaH6H, while the gDNA of DaH6H contains four exons and three introns, with the highest similarity to the gDNA of H6H from D. stramonium. DaH6H also exhibited the most identity of 90.5% with DsH6H in amino acids and harbored conserved 2-oxoglutarate binding motif and two iron binding motifs. The expression level of DaH6H was highest in the mature leaf, followed by the secondary root, and with no expression in the primary root based on qPCR analysis. Its expression was inhibited by MeJA. DaH6H was expressed in E. coli and a 39 kD recombinant protein was detected in SDS-PAGE. Comparison of the contents of scopolamine and hyoscyamine in various TAs-producing plants revealed that D. arborea was one of the rare scopolamine predominant plants. Cloning of DaH6H gene will allow more research in the molecular regulatory mechanism of TAs biosynthesis in distinct plants and provide a new candidate gene for scopolamine metabolic engineering.

  12. Detection specificity studies of bacteriophage adhesin-coated long-period grating-based biosensor

    NASA Astrophysics Data System (ADS)

    Koba, Marcin; Śmietana, Mateusz; Brzozowska, Ewa; Górska, Sabina; Mikulic, Predrag; Cusano, Andrea; Bock, Wojtek J.

    2015-09-01

    In this work, we present a label-free detection specificity study of an optical fiber long-period grating (LPG) biosensor working near the dispersion turning point of higher order cladding modes. The LPG sensor functionalized with bacteriophage adhesin is tested with specific and non-specific bacteria dry weight. We show that such biosensor is able to selectively bind, thus recognize different bacteria. We use bacteria dry weights of E. coli B as positive test and E. coli K12 and Salmonella enterica as negative tests. The resonance wavelength shift induced by E. coli B reaches over 90 nm, while for E. coli K12 and Salmonella enterica approximately 40 and 20 nm, respectively.

  13. A periodic density functional theory study of cumene formation catalyzed by H-mordenite.

    PubMed

    Rozanska, X; Barbosa, L A M M; van Santen, R A

    2005-02-17

    A periodic density functional theory study of the alkylation of benzene with propene in proton-exchanged mordenite has been achieved. The two different reaction routes that are usually proposed for this reaction, namely the direct and the step-by-step reaction pathways, have been investigated. The explicit consideration of the zeolite catalyst framework allows a better level of description of the interactions between the catalyst framework and the reaction than what is obtained with the cluster approach method. The direct reaction route is found to be the preferred one. It is observed that the cluster approach method, which does not describe the zeolite framework, is unable to qualitatively described the trend in activation energies. This is owing to the greater stabilization of larger transition state by the mordenite zeolite framework compared with smaller ones.

  14. Feasibility study of a periodic arc compressor in the presence of coherent synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Di Mitri, S.

    2016-01-01

    The advent of short electron bunches in high brightness linear accelerators has raised the awareness of the accelerator community to the degradation of the beam transverse emittance by coherent synchrotron radiation (CSR) emitted in magnetic bunch length compressors, transfer lines and turnaround arcs. Beam optics control has been proposed to mitigate that CSR effect. In this article, we enlarge on the existing literature by reviewing the validity of the linear optics approach in a periodic, achromatic arc compressor. We then study the dependence of the CSR-perturbed emittance to beam optics, mean energy, and bunch charge. The analytical findings are compared with particle tracking results. Practical considerations on CSR-induced energy loss and nonlinear particle dynamics are included. As a result, we identify the range of parameters that allows feasibility of an arc compressor for driving, for example, a free electron laser or a linear collider.

  15. Reference datasets for 2-treatment, 2-sequence, 2-period bioequivalence studies.

    PubMed

    Schütz, Helmut; Labes, Detlew; Fuglsang, Anders

    2014-11-01

    It is difficult to validate statistical software used to assess bioequivalence since very few datasets with known results are in the public domain, and the few that are published are of moderate size and balanced. The purpose of this paper is therefore to introduce reference datasets of varying complexity in terms of dataset size and characteristics (balance, range, outlier presence, residual error distribution) for 2-treatment, 2-period, 2-sequence bioequivalence studies and to report their point estimates and 90% confidence intervals which companies can use to validate their installations. The results for these datasets were calculated using the commercial packages EquivTest, Kinetica, SAS and WinNonlin, and the non-commercial package R. The results of three of these packages mostly agree, but imbalance between sequences seems to provoke questionable results with one package, which illustrates well the need for proper software validation.

  16. Performance of colloidal silica and ceria based slurries on CMP of Si-face 6H-SiC substrates

    NASA Astrophysics Data System (ADS)

    Chen, Guomei; Ni, Zifeng; Xu, Laijun; Li, Qingzhong; Zhao, Yongwu

    2015-12-01

    Colloidal silica and ceria based slurries, both using KMnO4 as an oxidizer, for chemical mechanical polishing (CMP) of Si-face (0 0 0 1) 6H-SiC substrate, were investigated to obtain higher material removal rate (MRR) and ultra-smooth surface. The results indicate that there was a significant difference in the CMP performance of 6H-SiC between silica and ceria based slurries. For the ceria based slurries, a higher MRR was obtained, especially in strong acid KMnO4 environment, and the maximum MRR (1089 nm/h) and a smoother surface with an average roughness Ra of 0.11 nm was achieved using slurries containing 2 wt% colloidal ceria, 0.05 M KMnO4 at pH 2. In contrast, due to the attraction between negative charged silica particles and positive charged SiC surface below pH 5, the maximum MRR of silica based slurry was only 185 nm/h with surface roughness Ra of 0.254 nm using slurries containing 6 wt% colloidal silica, 0.05 M KMnO4 at pH 6. The polishing mechanism was discussed based on the zeta potential measurements of the abrasives and the X-ray photoelectron spectroscopy (XPS) analysis of the polished SiC surfaces.

  17. Long-Term Observation of Triplex Surgery for Cataract after Phakic 6H Implantation for Super High Myopia

    PubMed Central

    Liu, Xin; Wang, Xiaoying; Lu, Yi; Zheng, Tianyu; Zhou, Xingtao

    2016-01-01

    Purpose. To analyze the safety, effectiveness, and stability of triplex surgery for phakic 6H anterior chamber phakic intraocular lens explantation and phacoemulsification with in-the-bag IOL implantation for super high myopia in long-term observations. Methods. This retrospective case series evaluated 16 eyes of 10 patients who underwent triplex surgery. Best corrected visual acuity (BCVA), endothelial cell density (ECD), and associated adverse events were evaluated. Results. The mean follow-up time after the triplex surgery was 46 ± 14 months. The mean logMAR BCVA was significantly improved after triplex surgery (P = 0.047). One eye developed endophthalmitis five days postoperatively and underwent pars plana vitrectomy (PPV). Five eyes with preoperative severe endothelial cell loss developed corneal decompensation and underwent keratoplasty at a mean time of 9.4 ± 2.6 months after the triplex surgery. One eye had graft failure and underwent a second keratoplasty. The eye developed rhegmatogenous retinal detachment and underwent PPV with silicone oil 18 months later. ECD before the triplex surgery was not significantly different compared with that at last follow-up (P = 0.495) apart from these five eyes. Three eyes (18.8%) developed posterior capsule opacification. Conclusions. Triplex surgery was safe and effective for phakic 6H related complicated cataracts. Early extraction before severe ECD loss is recommended. PMID:27190642

  18. Synthesis and biological activity of cocaine analogues. 2. 6H-[2]Benzopyrano[4,3-c]pyridin-6-ones.

    PubMed

    Lazer, E S; Hite, G J; Nieforth, K A; Stratford, E S

    1979-07-01

    1,2,3,4-Tetrahydro-2-methyl-6H-[2]benzopyrano[4,3-c]pyridin-6-one (20) and cis- and trans-1,2,3,4,4a,10b-hexahydro-2-methyl-6H-[2]benzopyrano[4,3-c]pyridin-6-one (3a and 3b) were synthesized. The design of 3b was based on the proposal that the active conformation of cocaine is one in which the phenyl and amino groups are arranged in a manner that will superimpose upon a beta-phenethylamine in a trans-staggered conformation. The compounds were compared with cocaine and tropacocaine for their ability to inhibit uptake of [3H]norepinephrine by rat brain synaptosomal preparations. The test compounds (IC50 = 3.2 X 10(-4) M, 20; 6.5 X 10(-4) M, 3a; and 3.2 X 10(-4) M, 3b; respectively) were considerably weaker than cocaine (IC50 = 5.8 X 10(-7) M) and tropacocaine (IC50 = 5.6 X 10(-6) M). Compound 3b showed selectivity at 1 X 10(-5) M for inhibiting the uptake of norepinephrine (36%). It inhibited dopamine (3%) and serotonin (0%) uptake to a much lesser extent, if at all, at this concentration.

  19. [Synthesis and spectra of transition metals complexes RE3L6(NO3)6(H2O)2].

    PubMed

    Zhao, Qing-shan; Mao, Ju-lin; Zhou, Hui-liang; Hu, Qi-lin; Liu, Wan-yi

    2009-09-01

    Schiff base 4-(p-dimethylaminobenzaldehydeamino)-4H-1,2,4-triazole(L) was synthesized from 4-amino-1,2,4-triazole and p-dimethylaminobenzaldehyde using acetic acid as the catalyst. The solid complexes RE3L6(NO3)6(H2O)2 (RE = Cu, Co, Zn, Cd; x = 3-6) were synthesized with 4-(p-dimethylaminobenzaldehydeamino)-4H-1,2,4-triazole and nitrate of transition metals in ethanol and characterized by elemental analysis, infrared spectroscopy, UV spectrum, and fluorescence spectrum. Experimental results showed that the free ligand is a thermally stable material, and its ethanol solution emitted intense blue fluorescence at the peak wavelength of 416 nm. The absorption band at about 406 nm can be assigned to the intrinsic absorption of C==N. Compared with the fluorescence emission of free ligand in ethanol solution, the emission of the complex of RE3L6 (NO3)6(H2O)2 was red-shifted to 445 nm and narrow in solution. RE(II) was coordinated with N atomy of triazole in 4-(p-dimethylaminobenzaldehydeamino)-4H-1,2,4-triazole.

  20. Vibrational spectra and dispersion analysis of K2Ni(SeO4)2·6H2O Tutton salt single crystal doped with K2Ni(SO4)2·6H2O

    NASA Astrophysics Data System (ADS)

    Ivanovski, Vladimir; Mayerhöfer, Thomas G.

    2013-10-01

    Dispersion analysis of the polarized IR reflectance spectra of K2Ni(SeO4)2·6H2O doped with K2Ni(SO4)2·6H2O has been performed. Vibrational parameters like oscillator strength, attenuation constant and frequency of the transversal phonons for the modes of Au symmetry type plus the orientation of the transition dipole moments for the modes of Bu symmetry type in the ac crystal plane have been obtained. The spectra-structure correlation of the H2O stretching vibrations show that bands appearing in the spectra for polarization of the external radiation oriented along the b axis are mainly due to the H2O stretching vibrations of one of the three crystallographically distinct sets of water molecules. The orientation of the transition dipoles of stretching vibrations of the selenate ion differ from the characteristic spectra of the sulfate analog in that no mutually perpendicular transition dipoles are found in the ac crystal plane. Water librational bands masked with the bands of the ν4(SO42-) mode in the sulfate analog have now been unveiled and assigned. The ratio between the oscillator strength and the attenuation constant appears to be a helpful tool in the assignment of the sulfate stretching vibrations and water librations. The vibrational and orientational characteristics of the ν4(SeO42-) modes were obtained. Тhe ν3(SO42-) frequency region of the isomorphously isolated SO42- ion in the K2Ni(SeO4)2·6H2O matrix was investigated in some detail. Contrary to the expected three, four bands can be identified. Three of them were assigned to ν3(SO42-) based on the orientation of the transition dipole moments. On the basis of the IR, but also Raman spectra of the pure and mixed crystals, a discussion of the influence of the potential field and the hydrogen bonds with the change in the volume of the unit cell is given.

  1. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats : Insights from a case study in Tillamook bay, Oregon, USA

    EPA Science Inventory

    This study validates the ecological relevance of estuarine habitat types to the benthic macrofaunal community and, together with previous similar studies, suggests they can serve as elements in ecological periodic tables of benthic macrofaunal usage in the bioregion. We compared...

  2. Isolation of H5N6, H7N9 and H9N2 avian influenza A viruses from air sampled at live poultry markets in China, 2014 and 2015

    PubMed Central

    Zhou, Jie; Wu, Jie; Zeng, Xianqiao; Huang, Guofeng; Zou, Lirong; Song, Yingchao; Gopinath, Divya; Zhang, Xin; Kang, Min; Lin, Jinyan; Cowling, Benjamin J; Lindsley, William G.; Ke, Changwen; Peiris, Joseph Sriyal Malik; Yen, Hui-Ling

    2016-01-01

    Zoonotic infections by avian influenza viruses occur at the human–poultry interface, but the modes of transmission have not been fully investigated. We assessed the potential for airborne and fomite transmission at live poultry markets in Guangzhou city and in Hong Kong Special Administrative Region (SAR), China, during 2014 and 2015. Viral genome and infectious avian influenza A viruses of H5N6, H7N9, and H9N2 subtypes were detected predominantly from particles larger or equal to 1 μm in diameter in the air sampled with cyclone-based bioaerosol samplers at the live poultry markets in Guangzhou. Influenza A(H9N2) viruses were ubiquitously isolated every month during the study period from air and environmental swabs, and different lineages of H9N2 virus were isolated from markets where chickens and minor land-based poultry were sold. The use of de-feathering devices increased the quantity of virus-laden airborne particles while market closure reduced the amount of such particles. The results highlight the possibility of airborne transmission of avian influenza viruses among poultry or from poultry to humans within such settings. This may explain epidemiological observations in which some patients with H7N9 infection reported being in markets but no direct contact with live poultry or poultry stalls. PMID:27608369

  3. Isolation of H5N6, H7N9 and H9N2 avian influenza A viruses from air sampled at live poultry markets in China, 2014 and 2015.

    PubMed

    Zhou, Jie; Wu, Jie; Zeng, Xianqiao; Huang, Guofeng; Zou, Lirong; Song, Yingchao; Gopinath, Divya; Zhang, Xin; Kang, Min; Lin, Jinyan; Cowling, Benjamin J; Lindsley, William G; Ke, Changwen; Peiris, Joseph Sriyal Malik; Yen, Hui-Ling

    2016-09-01

    Zoonotic infections by avian influenza viruses occur at the human-poultry interface, but the modes of transmission have not been fully investigated. We assessed the potential for airborne and fomite transmission at live poultry markets in Guangzhou city and in Hong Kong Special Administrative Region (SAR), China, during 2014 and 2015. Viral genome and infectious avian influenza A viruses of H5N6, H7N9, and H9N2 subtypes were detected predominantly from particles larger or equal to 1 μm in diameter in the air sampled with cyclone-based bioaerosol samplers at the live poultry markets in Guangzhou. Influenza A(H9N2) viruses were ubiquitously isolated every month during the study period from air and environmental swabs, and different lineages of H9N2 virus were isolated from markets where chickens and minor land-based poultry were sold. The use of de-feathering devices increased the quantity of virus-laden airborne particles while market closure reduced the amount of such particles. The results highlight the possibility of airborne transmission of avian influenza viruses among poultry or from poultry to humans within such settings. This may explain epidemiological observations in which some patients with H7N9 infection reported being in markets but no direct contact with live poultry or poultry stalls.

  4. Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period

    NASA Technical Reports Server (NTRS)

    Morgenstern, John; Norstrud, Nicole; Sokhey, Jack; Martens, Steve; Alonso, Juan J.

    2013-01-01

    Lockheed Martin Aeronautics Company (LM), working in conjunction with General Electric Global Research (GE GR), Rolls-Royce Liberty Works (RRLW), and Stanford University, herein presents results from the "N+2 Supersonic Validations" contract s initial 22 month phase, addressing the NASA solicitation "Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period." This report version adds documentation of an additional three month low boom test task. The key technical objective of this effort was to validate integrated airframe and propulsion technologies and design methodologies. These capabilities aspired to produce a viable supersonic vehicle design with environmental and performance characteristics. Supersonic testing of both airframe and propulsion technologies (including LM3: 97-023 low boom testing and April-June nozzle acoustic testing) verified LM s supersonic low-boom design methodologies and both GE and RRLW's nozzle technologies for future implementation. The N+2 program is aligned with NASA s Supersonic Project and is focused on providing system-level solutions capable of overcoming the environmental and performance/efficiency barriers to practical supersonic flight. NASA proposed "Initial Environmental Targets and Performance Goals for Future Supersonic Civil Aircraft". The LM N+2 studies are built upon LM s prior N+3 100 passenger design studies. The LM N+2 program addresses low boom design and methodology validations with wind tunnel testing, performance and efficiency goals with system level analysis, and low noise validations with two nozzle (GE and RRLW) acoustic tests.

  5. Case-control study of the PERIOD3 clock gene length polymorphism and colorectal adenoma formation

    PubMed Central

    ALEXANDER, MELANNIE; BURCH, JAMES B.; STECK, SUSAN E.; CHEN, CHIN-FU; HURLEY, THOMAS G.; CAVICCHIA, PHILIP; RAY, MEREDITH; SHIVAPPA, NITIN; GUESS, JACLYN; ZHANG, HONGMEI; YOUNGSTEDT, SHAWN D.; CREEK, KIM E.; LLOYD, STEPHEN; YANG, XIAOMING; HÉBERT, JAMES R.

    2015-01-01

    Clock genes are expressed in a self-perpetuating, circadian pattern in virtually every tissue including the human gastrointestinal tract. They coordinate cellular processes critical for tumor development, including cell proliferation, DNA damage response and apoptosis. Circadian rhythm disturbances have been associated with an increased risk for colon cancer and other cancers. This mechanism has not been elucidated, yet may involve dysregulation of the ‘period’ (PER) clock genes, which have tumor suppressor properties. A variable number tandem repeat (VNTR) in the PERIOD3 (PER3) gene has been associated with sleep disorders, differences in diurnal hormone secretion, and increased premenopausal breast cancer risk. Susceptibility related to PER3 has not been examined in conjunction with adenomatous polyps. This exploratory case-control study was the first to test the hypothesis that the 5-repeat PER3 VNTR sequence is associated with increased odds of adenoma formation. Information on demographics, medical history, occupation and lifestyle was collected prior to colonoscopy. Cases (n=49) were individuals with at least one histopathologically confirmed adenoma. Controls (n=97) included patients with normal findings or hyperplastic polyps not requiring enhanced surveillance. Unconditional multiple logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs), after adjusting for potential confounding. Adenomas were detected in 34% of participants. Cases were more likely to possess the 5-repeat PER3 genotype relative to controls (4/5 OR, 2.1; 95% CI, 0.9–4.8; 5/5 OR, 5.1; 95% CI, 1.4–18.1; 4/5+5/5 OR, 2.5; 95% CI, 1.7–5.4). Examination of the Oncomine microarray database indicated lower PERIOD gene expression in adenomas relative to adjacent normal tissue. Results suggest a need for follow-up in a larger sample. PMID:25501848

  6. MD-2 as the target of a novel small molecule, L6H21, in the attenuation of LPS-induced inflammatory response and sepsis

    PubMed Central

    Wang, Yi; Shan, Xiaoou; Chen, Gaozhi; Jiang, Lili; Wang, Zhe; Fang, Qilu; Liu, Xing; Wang, Jingying; Zhang, Yali; Wu, Wencan; Liang, Guang

    2015-01-01

    Background and Purpose Myeloid differentiation 2 (MD-2) recognizes LPS, which is required for TLR4 activation, and represents an attractive therapeutic target for severe inflammatory disorders. We previously found that a chalcone derivative, L6H21, could inhibit LPS-induced overexpression of TNF-α and IL-6 in macrophages. Here, we performed a series of biochemical experiments to investigate whether L6H21 specifically targets MD-2 and inhibits the interaction and signalling transduction of LPS-TLR4/MD-2. Experimental Approach The binding affinity of L6H21 to MD-2 protein was analysed using computer docking, surface plasmon resonance analysis, elisa, fluorescence measurements and flow cytometric analysis. The effects of L6H21 on MAPK and NF-κB signalling were determined using EMSA, fluorescence staining, Western blotting and immunoprecipitation. The anti-inflammatory effects of L6H21 were confirmed using elisa and RT-qPCR in vitro. The anti-inflammatory effects of L6H21 were also evaluated in septic C57BL/6 mice. Key Results Compound L6H21 inserted into the hydrophobic region of the MD-2 pocket, forming hydrogen bonds with Arg90 and Tyr102 in the MD-2 pocket. In vitro, L6H21 subsequently suppressed MAPK phosphorylation, NF-κB activation and cytokine expression in macrophages stimulated by LPS. In vivo, L6H21 pretreatment improved survival, prevented lung injury, decreased serum and hepatic cytokine levels in mice subjected to LPS. In addition, mice with MD-2 gene knockout were universally protected from the effects of LPS-induced septic shock. Conclusions and Implications Overall, this work demonstrated that the new chalcone derivative, L6H21, is a potential candidate for the treatment of sepsis. More importantly, the data confirmed that MD-2 is an important therapeutic target for inflammatory disorders. PMID:26076332

  7. Cross-type orbital ordering in the layered hybrid organic-inorganic compound (C6H5CH2CH2NH3 )2CuCl4

    NASA Astrophysics Data System (ADS)

    Nugroho, A. A.; Hu, Z.; Kuo, C. Y.; Haverkort, M. W.; Pi, T. W.; Onggo, D.; Valldor, M.; Tjeng, L. H.

    2016-11-01

    We have studied the magnetic properties and the underlying type of orbital ordering in the layered hybrid organic-inorganic compound (C6H5CH2CH2NH3 )2CuCl4 by using ac-magnetic susceptibility and polarization-dependent soft-x-ray absorption spectroscopy at the Cu-L2 and Cu-L3 edges. We have established that the compound has a long-range ferromagnetic ordering both in plane and out of plane and we found from the analysis of the absorption spectra that the orbital ordering of the Cu2 + holes involves the cross-type dx2-z2/dy2-z2 arrangement which is different from the dx2-y2 arrangement found in the parent compounds of the high-Tc cuprate superconductors.

  8. Low energy electron irradiation induced deep level defects in 6H-SiC: the implication for the microstructure of the deep levels E1/E2.

    PubMed

    Chen, X D; Yang, C L; Gong, M; Ge, W K; Fung, S; Beling, C D; Wang, J N; Lui, M K; Ling, C C

    2004-03-26

    N-type 6H-SiC samples irradiated with electrons having energies of E(e)=0.2, 0.3, 0.5, and 1.7 were studied by deep level transient technique. No deep level was detected at below 0.2 MeV irradiation energy while for E(e)>/=0.3 MeV, deep levels ED1, E(1)/E(2), and E(i) appeared. By considering the minimum energy required to displace the C atom or the Si atom in the SiC lattice, it is concluded that generation of the deep levels E(1)/E(2), as well as ED1 and E(i), involves the displacement of the C atom in the SiC lattice.

  9. Low Energy Electron Irradiation Induced Deep Level Defects in 6H-SiC: The Implication for the Microstructure of the Deep Levels E1/E2

    NASA Astrophysics Data System (ADS)

    Chen, X. D.; Yang, C. L.; Gong, M.; Ge, W. K.; Fung, S.; Beling, C. D.; Wang, J. N.; Lui, M. K.; Ling, C. C.

    2004-03-01

    N-type 6H-SiC samples irradiated with electrons having energies of Ee=0.2, 0.3, 0.5, and 1.7 were studied by deep level transient technique. No deep level was detected at below 0.2MeV irradiation energy while for Ee≥0.3 MeV, deep levels ED1, E1/E2, and Ei appeared. By considering the minimum energy required to displace the C atom or the Si atom in the SiC lattice, it is concluded that generation of the deep levels E1/E2, as well as ED1 and Ei, involves the displacement of the C atom in the SiC lattice.

  10. New phenylpropanoid and 6H-dibenzo[b,d]pyran-6-one derivatives from the stems of Dasymaschalon rostratum.

    PubMed

    Yu, Zhang-Xin; Niu, Zhi-Gang; Li, Xiao-Bao; Zheng, Cai-Juan; Song, Xin-Ming; Chen, Guang-Ying; Song, Xiao-Ping; Han, Chang-Ri; Wu, Shu-Xian

    2017-02-14

    Three new phenylpropanoid derivatives, dasymaroacid A (1), dasymaroesters B and C (2 and 3), and one new polyoxygenated 6H-dibenzo[b,d]pyran-6-one derivative dasymarolactone D (4), together with seven known compounds (5-11), were isolated from the stems of Dasymaschalon rostratum Merr. Compounds 1 and 2 are unusual phenylpropanoid derivatives with a polymethyl substituted cyclopentene conjugated diketone as a substituent, and 3 is a unique cinnamic acid detective with a polymethyl substituted cyclohexene conjugated triketone as a substituent. Their structures were elucidated by extensive spectroscopic methods and chemical method, and 4 was further confirmed by the single crystal X-ray diffraction method. Compounds 1-4 and 7 showed weak anti-HIV-1 activities with EC50 values ranged from 16.44 to 25.91μM.

  11. Stable Electrical Operation of 6H-SiC JFETs and ICs for Thousands of Hours at 500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Spry, David J.; Chen, Liang-Yu; Beheim, Glenn M.; Okojie, Robert S.; Chang, Carl W.; Meredith, Roger D.; Ferrier, Terry L.; Evans, Laura J.; Krasowski, Michael J.; Prokop, Norman F.

    2008-01-01

    The fabrication and testing of the first semiconductor transistors and small-scale integrated circuits (ICs) to achieve up to 3000 h of stable electrical operation at 500 C in air ambient is reported. These devices are based on an epitaxial 6H-SiC junction field-effect transistor process that successfully integrated high temperature ohmic contacts, dielectric passivation, and ceramic packaging. Important device and circuit parameters exhibited less than 10% of change over the course of the 500 C operational testing. These results establish a new technology foundation for realizing durable 500 C ICs for combustion-engine sensing and control, deep-well drilling, and other harsh-environment applications.

  12. Activation and control of visible single defects in 4H-, 6H-, and 3C-SiC by oxidation

    SciTech Connect

    Lohrmann, A.; Klein, J. R.; Prawer, S.; McCallum, J. C.; Castelletto, S.; Ohshima, T.; Bosi, M.; Negri, M.; Johnson, B. C.

    2016-01-11

    In this work, we present the creation and characterisation of single photon emitters at the surface of 4H- and 6H-SiC, and of 3C-SiC epitaxially grown on silicon. These emitters can be created by annealing in an oxygen atmosphere at temperatures above 550 °C. By using standard confocal microscopy techniques, we find characteristic spectral signatures in the visible region. The excited state lifetimes are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice. HF-etching is shown to effectively annihilate the defects and to restore an optically clean surface. The defects described in this work have ideal characteristics for broadband single photon generation in the visible spectral region at room temperature and for integration into nanophotonic devices.

  13. High power operation of a nitrogen doped, vanadium compensated, 6H-SiC extrinsic photoconductive switch

    SciTech Connect

    Sullivan, J. S.

    2014-04-28

    We report the high power operation of nitrogen doped, vanadium compensated, 6H-SiC, extrinsic photoconductive switches with improved vanadium and nitrogen dopant density. Photoconductive switching tests are performed on 1 mm thick, m-plane, switch substrates at switch voltage and currents up to 17 kV and 1.5 kA, respectively. Sub-ohm minimum switch on resistance is achieved for peak optical intensities ≥35 MW/cm{sup 2} at 532 nm applied to the switch facet. A reduction of greater than nine orders of magnitude is observed in switch material resistivity between dark and illuminated states.

  14. High-Field Fast-Risetime Pulse Failures in 4H- and 6H-SiC pn Junction Diodes

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Fazi, Christian

    1996-01-01

    We report the observation of anomalous reverse breakdown behavior in moderately doped (2-3 x 10(exp 17 cm(exp -3)) small-area micropipe-free 4H- and 6H-SiC pn junction diodes. When measured with a curve tracer, the diodes consistently exhibited very low reverse leakage currents and sharp repeatable breakdown knees in the range of 140-150 V. However, when subjected to single-shot reverse bias pulses (200 ns pulsewidth, 1 ns risetime), the diodes failed catastrophically at pulse voltages of less than 100 V. We propose a possible mechanism for this anomalous reduction in pulsed breakdown voltage relative to dc breakdown voltage. This instability must be removed so that SiC high-field devices can operate with the same high reliability as silicon power devices.

  15. Growth of fcc(111) Dy multi-height islands on 6H-SiC(0001) graphene.

    PubMed

    Hershberger, M T; Hupalo, M; Thiel, P A; Tringides, M C

    2013-06-05

    Graphene based spintronic devices require an understanding of the growth of magnetic metals. Rare earth metals have large bulk magnetic moments so they are good candidates for such applications, and it is important to identify their growth mode. Dysprosium was deposited on epitaxial graphene, prepared by thermally annealing 6H-SiC(0001). The majority of the grown islands have triangular instead of hexagonal shapes. This is observed both for single layer islands nucleating at the top of incomplete islands and for fully completed multi-height islands. We analyze the island shape distribution and stacking sequence of successively grown islands to deduce that the Dy islands have fcc(111) structure, and that the triangular shapes result from asymmetric barriers to corner crossing.

  16. Activation and control of visible single defects in 4H-, 6H-, and 3C-SiC by oxidation

    NASA Astrophysics Data System (ADS)

    Lohrmann, A.; Castelletto, S.; Klein, J. R.; Ohshima, T.; Bosi, M.; Negri, M.; Lau, D. W. M.; Gibson, B. C.; Prawer, S.; McCallum, J. C.; Johnson, B. C.

    2016-01-01

    In this work, we present the creation and characterisation of single photon emitters at the surface of 4H- and 6H-SiC, and of 3C-SiC epitaxially grown on silicon. These emitters can be created by annealing in an oxygen atmosphere at temperatures above 550 °C. By using standard confocal microscopy techniques, we find characteristic spectral signatures in the visible region. The excited state lifetimes are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice. HF-etching is shown to effectively annihilate the defects and to restore an optically clean surface. The defects described in this work have ideal characteristics for broadband single photon generation in the visible spectral region at room temperature and for integration into nanophotonic devices.

  17. Simulation and Experiment on Surface Morphology and Mechanical Properties Response in Nano-Indentation of 6H-SiC

    NASA Astrophysics Data System (ADS)

    Li, Chen; Zhang, Feihu; Meng, Binbin; Ma, Zhaokai

    2017-02-01

    The nano-indentation test for 6H-SiC is carried out with a Berkovich indenter. The indentation surface morphology is analyzed by SEM, which show that when the maximum load P max is 8 mN, there is only plastic deformation and no cracks on the surface of workpiece after unloading process, and when P max is 10 mN, there is the initiation of crack occurring on the surface of workpiece after unloading process. Based on the strain hardening model, the three-dimensional finite element method of nano-indentation for 6H-SiC is carried out. Simulation results show that in the unloading process the maximum stress and the maximum strain occur in the contact area between the workpiece with the indenter edges, which is consistent with the experimental results. When propagate to the surface from the subsurface, the cracks are subjected to the type I stress and the type II stress due to elastic recovery. After propagating to surface of workpiece, the cracks propagate along a fixed direction because the proportion of type I stress is much larger than that of type II stress. The influence of the cleavage plane on the propagation direction of cracks is obvious. The cracks propagate more easily when the indenter edges are along cleavage plane. The indentation depth and residual depth increase with the increase of P max. While, the elastic recovery rate gradually decreases and tends to be stable with the increase of P max. When P max is <10 mN, the micro-hardness and the elastic modulus increase linearly with the increase of P max. When P max exceeds 10 mN, the micro-hardness decreases with the increase of P max and then gradually tends to be stable, and the elastic modulus increases by power function with the increase of P max and then gradually tends to be stable.

  18. Electronic states of the C6H6/Cu{111} system: Energetics, femtosecond dynamics, and adsorption morphology

    NASA Astrophysics Data System (ADS)

    Velic, D.; Hotzel, A.; Wolf, M.; Ertl, G.

    1998-11-01

    Two-photon-photoemission (2PPE) spectroscopy is employed to characterize electronic states of a bilayer C6H6/Cu{111} system at 85 K. The unoccupied benzene π* e2u state is observed with a binding energy of 4.6 eV above the Fermi level. This result agrees with inverse-photoemission (IPE) data and provides a case where the determination of the binding energy is identical for 2PPE and IPE. The π* e2u state is assigned in the 2PPE scheme as a final state which is the first observed final state in 2PPE of adsorbate-surface systems. The dependence of the electron dynamics on the morphology of an incomplete adsorption layer is also investigated. Two (n=1)-like image potential states A and B are observed which presumably originate from two different C6H6 adsorption geometries in the bilayer regime. The two image states A and B are characterized by electron effective masses of 1.1 and 1.9 me, binding energies of 3.30 and 3.45 eV above the Fermi level, and lifetimes of 40 and 20 fs, respectively. The dielectric continuum model and the Kronig-Penney model are employed to simulate the origin of (n=1)-like image states. The work function decreases from 4.9 eV at clean Cu{111} to 4.0 eV at bilayer coverage. The change of the work function and the observation of two image states suggest the redefining of the ratio of the numbers of benzene molecules in the first and the second layers of the bilayer regime to approximately 1:1 instead of 1:2, as previously reported. 2PPE is shown to be sensitive to the changes of morphologies, local work functions, and adsorbate-surface potentials during the layer formation.

  19. Adsorption and decomposition of cyclohexanone (C6H10O) on Pt(111) and the (2 × 2) and (√3 × √3)r30°-Sn/Pt(111) surface alloys.

    PubMed

    Kim, Jooho; Welch, Lindsey A; Olivas, Amelia; Podkolzin, Simon G; Koel, Bruce E

    2010-11-02

    Adsorption and decomposition of cyclohexanone (C(6)H(10)O) on Pt(111) and on two ordered Pt-Sn surface alloys, (2 × 2)-Sn/Pt(111) and (√3 × √3)R30°-Sn/Pt(111), formed by vapor deposition of Sn on the Pt(111) single crystal surface were studied with TPD, HREELS, AES, LEED, and DFT calculations with vibrational analyses. Saturation coverage of C(6)H(10)O was found to be 0.25 ML, independent of the Sn surface concentration. The Pt(111) surface was reactive toward cyclohexanone, with the adsorption in the monolayer being about 70% irreversible. C(6)H(10)O decomposed to yield CO, H(2)O, H(2), and CH(4). Some C-O bond breaking occurred, yielding H(2)O and leaving some carbon on the surface after TPD. HREELS data showed that cyclohexanone decomposition in the monolayer began by 200 K. Intermediates from cyclohexanone decomposition were also relatively unstable on Pt(111), since coadsorbed CO and H were formed below 250 K. Surface Sn allowed for some cyclohexanone to adsorb reversibly. C(6)H(10)O dissociated on the (2 × 2) surface to form CO and H(2)O at low coverages, and methane and H(2) in smaller amounts than on Pt(111). Adsorption of cyclohexanone on (√3 × √3)R30°-Sn/Pt(111) at 90 K was mostly reversible. DFT calculations suggest that C(6)H(10)O adsorbs on Pt(111) in two configurations: by bonding weakly through oxygen to an atop Pt site and more strongly through simultaneously oxygen and carbon of the carbonyl to a bridged Pt-Pt site. In contrast, on alloy surfaces, C(6)H(10)O bonds preferentially to Sn. The presence of Sn, furthermore, is predicted to make the formation of the strongly bound C(6)H(10)O species bonding through O and C, which is a likely decomposition precursor, thermodynamically unfavorable. Alloying with Sn, thus, is shown to moderate adsorptive and reactive activity of Pt(111).

  20. [Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)].

    PubMed

    Gusev, E I; Skvortsova, V I; Miasoedov, N F; Nezavibat'ko, V N; Zhuravleva, E Iu; Vanichkin, A V

    1997-01-01

    Efficiency of Semax (synthetic derivative of ACTH-4-10) was studied in 30 patients in acute period of hemispherical ischemic stroke. Control group consisted of 80 patients with the strokes analogous in severity and location of the damages and which were treated by conventional therapy. Different clinical rating scales were used for both objectivization of the severity of the patients' state and estimation of the degree of neurological defect. The control of Semax influence on the functional state of the brain included monitoring of EEG with mapping, repeated analysis of somatosensory evoked potentials and their mapping. It was established that including of Semax in combined intensive therapy of acute ischemic stroke had some influence on the rate of restoration of the damaged neurological functions in terms of increasing the regress of general cerebral and focal, especially motor disorders. The most effective daily doses were 12 mg for patients with strokes of moderate severity and 18 mg for patients with severe strokes (treatment course--5 and 10 days).

  1. Unsaturated hydrocarbons adsorbed on low coordinated Pd surface: A periodic DFT study

    NASA Astrophysics Data System (ADS)

    Belelli, Patricia G.; Ferullo, Ricardo M.; Castellani, Norberto J.

    2010-02-01

    In this work, the adsorption of several unsaturated hydrocarbon molecules on a stepped Pd(4 2 2) surface was studied. Using a periodic method based on the Density Functional Theory (DFT) formalism, different adsorption geometries for ethylene, three butene isomers ( cis/ trans-2-butene and 1-butene), acetylene and 2-butyne were investigated. The results were compared with those obtained for a free defect surface as Pd(1 1 1). The 1-butene is more stable on the free defect surface than on Pd(4 2 2). On the stepped surface, the olefins adsorb tilted towards the step and increases, in almost all the cases, the magnitude of the adsorption energy. Conversely, the 3-fold site is the most stable for the alkynes adsorption on the stepped surface, as it was found on Pd(1 1 1). The analysis of the dipole moment change indicate a charge transfer from the double bond of the olefin to the metallic surface, being higher for the Pd(1 1 1) surface. In case of the alkynes, an important back-donation is produced. Except the alkynes and the 1-butene molecule, the results show the preference of ethylene and cis/ trans-2-butene to be adsorbed on the stepped surface. These observations are related with experimental catalytic results.

  2. Butanethiol adsorption and dissociation on Ag (111): A periodic DFT study

    NASA Astrophysics Data System (ADS)

    Li, Aixiao; Piquemal, Jean-Philip; Richardi, Johannes; Calatayud, Monica

    2016-04-01

    The molecular and dissociative adsorption of butanethiol (C4H9SH) on regular Ag (111) surfaces has been studied by means of periodic ab initio density functional techniques. In molecular form, butanethiol is bound to the surface only by weak polarization-induced forces with the C-S axis tilted by 38° relative to the normal surface. The S atom occupies a position between a hollow fcc and a bridge site. In the dissociative adsorption process, the S-H bond breaks leading to butanethiolate. The S atom of the thiolate also occupies a threefold position, slightly displaced to a hollow fcc site compared to the thiol adsorption case. The C-S axis of the thiolate is tilted by about 37°. The calculated adsorption energies show that the butanethiol and butanethiolate have similar adsorption ability. The computed reaction pathway for the S-H dissociation gives an activation energy of 0.98 eV indicating that the thiolate formation from thiol, although not spontaneous at room temperature, might be feasible on silver surfaces. The dissociation process induces both adsorbate and surface polarization with a significant charge transfer from the substrate to the adsorbate.

  3. Estimating the dim light melatonin onset of adolescents within a 6-h sampling window: the impact of sampling rate and threshold method

    PubMed Central

    Crowley, Stephanie J.; Suh, Christina; Molina, Thomas A.; Fogg, Louis F.; Sharkey, Katherine M.; Carskadon, Mary A.

    2016-01-01

    Objective/Background Circadian rhythm sleep-wake disorders often manifest during the adolescent years. Measurement of circadian phase such as the Dim Light Melatonin Onset (DLMO) improves diagnosis and treatment of these disorders, but financial and time costs limit the use of DLMO phase assessments in clinic. The current analysis aims to inform a cost-effective and efficient protocol to measure the DLMO in older adolescents by reducing the number of samples and total sampling duration. Patients/Methods A total of 66 healthy adolescents (26 males) aged 14.8 to 17.8 years participated in a study in which sleep was fixed for one week before they came to the laboratory for saliva collection in dim light (<20 lux). Two partial 6-h salivary melatonin profiles were derived for each participant. Both profiles began 5 h before bedtime and ended 1 h after bedtime, but one profile was derived from samples taken every 30 mins (13 samples) and the other from samples taken every 60 mins (7 samples). Three standard thresholds (first 3 melatonin values mean + 2 SDs, 3 pg/mL, and 4 pg/mL) were used to compute the DLMO. Agreement between DLMOs derived from 30-min and 60-min sampling rates was determined using a Bland-Altman analysis; agreement between sampling rate DLMOs was defined as ± 1 h. Results and Conclusions Within a 6-h sampling window, 60-min sampling provided DLMO estimates that were within ± 1 h of DLMO from 30-min sampling, but only when an absolute threshold (3 pg/mL or 4 pg/mL) was used to compute the DLMO. Future analyses should be extended to include adolescents with circadian rhythm sleep-wake disorders. PMID:27318227

  4. Crossed beam reaction of cyano radicals with hydrocarbon molecules. I. Chemical dynamics of cyanobenzene (C6H5CN; X 1A1) and perdeutero cyanobenzene (C6D5CN; X 1A1) formation from reaction of CN(X 2Σ+) with benzene C6H6(X 1A1g), and d6-benzene C6D6(X 1A1g)

    NASA Astrophysics Data System (ADS)

    Balucani, N.; Asvany, O.; Chang, A. H. H.; Lin, S. H.; Lee, Y. T.; Kaiser, R. I.; Bettinger, H. F.; Schleyer, P. v. R.; Schaefer, H. F.

    1999-10-01

    The chemical reaction dynamics to form cyanobenzene C6H5CN(X 1A1), and perdeutero cyanobenzene C6D5CN(X 1A1) via the neutral-neutral reaction of the cyano radical CN(X 2Σ+), with benzene C6H6(X 1A1g) and perdeutero benzene C6D6(X 1A1g), were investigated in crossed molecular beam experiments at collision energies between 19.5 and 34.4 kJ mol-1. The laboratory angular distributions and time-of-flight spectra of the products were recorded at mass to charge ratios m/e=103-98 and 108-98, respectively. Forward-convolution fitting of our experimental data together with electronic structure calculations (B3LYP/6-311+G**) indicate that the reaction is without entrance barrier and governed by an initial attack of the CN radical on the carbon side to the aromatic π electron density of the benzene molecule to form a Cs symmetric C6H6CN(C6D6CN) complex. At all collision energies, the center-of-mass angular distributions are forward-backward symmetric and peak at π/2. This shape documents that the decomposing intermediate has a lifetime longer than its rotational period. The H/D atom is emitted almost perpendicular to the C6H5CN plane, giving preferentially sideways scattering. This experimental finding can be rationalized in light of the electronic structure calculations depicting a H-C-C angle of 101.2° in the exit transition state. The latter is found to be tight and located about 32.8 kJ mol-1 above the products. Our experimentally determined reaction exothermicity of 80-95 kJ mol-1 is in good agreement with the theoretically calculated one of 94.6 kJ mol-1. Neither the C6H6CN adduct nor the stable iso cyanobenzene isomer C6H5NC were found to contribute to the scattering signal. The experimental identification of cyanobenzene gives a strong background for the title reaction to be included with more confidence in reaction networks modeling the chemistry in dark, molecular clouds, outflow of dying carbon stars, hot molecular cores, as well as the atmosphere of hydrocarbon

  5. Photoelectron spectroscopy study of AlN films grown on n-type 6H-SiC by MOCVD

    NASA Astrophysics Data System (ADS)

    Liang, F.; Chen, P.; Zhao, D. G.; Jiang, D. S.; Zhao, Z. J.; Liu, Z. S.; Zhu, J. J.; Yang, J.; Liu, W.; He, X. G.; Li, X. J.; Li, X.; Liu, S. T.; Yang, H.; Liu, J. P.; Zhang, L. Q.; Zhang, Y. T.; Du, G. T.

    2016-09-01

    Photoelectron spectroscopy has been employed to analyze the content and chemical states of the elements on the surface of AlN films with different thickness, which are synthesized by metalorganic chemical vapor deposition on the n-type SiC substrates under low pressure. It is found that, besides the carbon and gallium on the AlN surface, the atom percentage of surface oxygen increases from 4.9 to 8.4, and the electron affinity also increases from 0.36 to 0.97 eV, when the thickness of AlN films increase from 50 to 400 nm. Furthermore, accompanying with the high-resolution XPS spectra of the O 1s, it is speculated that surface oxygen may be the major influence on the electron affinity, where the surface oxygen changes the surface chemical states through replacing N to form Al-O bond and Ga-O bond, although there are also a few of Ga and C contaminations in the chemical sate of Ga-O and C-C, respectively.

  6. Experimental study of flow in a channel with a periodically heated wall

    NASA Astrophysics Data System (ADS)

    Inasawa, Ayumu; Taneda, Keinosuke; Floryan, Jerzy M.

    2015-11-01

    Flows in a channel with spatially periodic wall heating are examined experimentally at the Reynolds numbers below Re = 20 and at the Rayleigh number based on the amplitude of the periodic heating and the channel half width Rap = 3500, to realize the super-thermohydrophobic effect leading to a significant drag reduction (Floryan, 2012). The periodic heating is applied at the lower wall while the temperature of the upper wall is uniform and controlled. The results show that steady separation bubbles are created by periodic heating, which separate the main stream from the wall and, thus, the net friction drag is reduced. It is also found that the separation bubbles are strengthened when the average temperature of the lower wall exceeds that of the upper wall. Comparisons between the experiments and the theoretical results are presented.

  7. Neonatal Infection with Neisseria meningitidis: Analysis of a 97-Year Period Plus Case Study

    PubMed Central

    Bülbül, Ali; Cömert, Serdar; Uslu, Sinan; Arslan, Selda; Nuhoglu, Asiye

    2014-01-01

    Neisseria meningitidis is one of the major causes of meningitis in children and adolescents, but it is rarely found during the neonatal period. Here, we describe a neonate with meningococcal sepsis who was admitted to the hospital on postnatal day 10, and we discuss the clinical features of neonatal infection with N. meningitidis in relation to the literature (analysis of a 97-year period). PMID:25031437

  8. An Orbital Period Study of the W UMa-Type Binary RZ Comae Berenicis

    NASA Astrophysics Data System (ADS)

    Qian, Sheng-Bang; He, Jia-Jia

    2005-12-01

    New photoelectric and CCD photometry observations of a short-period W UMa-type binary system, RZ Com, are presented. The light curves of Broglia (1960, Contr. Milano-Merate, 165) were symmetric in V band, while the present light curve shows a typical O'Connell effect, with Maximum I brighter than Maximum II by 0.015mag. It is found that the light curve of the binary star has changed from W-subtype to A-subtype according to Binnendijk's classification. This variation may be caused by the activity of dark spot on the primary component. Combining four newly determined times of the light minimum with others published in the literature, the orbital period change of the system was investigated. A small-amplitude oscillation (A = 0.0058 d), with a period of 44.8yr has been discovered to be superimposed on a long-term period increase with a rate of dP/dt = +4.12 × 10-8 d yr-1. The period oscillation can be explained either by the light-time effect via the presence of an unseen third body or by magnetic-activity cycles of the components. The mass ratio of RZ Com is q = 0.43. The secular period variation is in agreement with the conclusions of Qian (2001, MNRAS, 328, 914; 2003, MNRAS, 342, 1260). This indicates that it is on the TRO-controlled stage of the evolutionary scheme proposed by Qian.

  9. Migraine and periodic limb movement disorders in sleep in children: a preliminary case–control study

    PubMed Central

    2013-01-01

    Background The relationships between sleep and headaches are complex and manifold. About the variety of phenomena that can disrupt the sleep macrostructure and can impact its restorative function, the periodic limb movements disorder (PLMd) can be considered as the most powerful. No studies are known about the role of PLMd in the pathophysiology of migraine in children. Aim of study is to assess the prevalence of PLMd and migraine and their relationship with disability and pain intensity in a pediatric sample, referred for migraine without aura by pediatricians. Methods After a preliminary sleep habits screening with the Sleep Disturbances Scale for Children, 34 migraine subjects affected by migraine without aura (20 M, 14 F) (mean age 9.08; SD ± 2.28) and 51 volunteers healthy children (28 M, 23 F) (mean age 9.37; SD ± 1.81) accepted to underwent overnight PSG recordings in the Sleep Laboratory of the Clinic of Child and Adolescent Neuropsychiatry, in order to define the macrostructural sleep characteristics and the prevalence of PLMd. Subsequently, the migraineurs sample was studied in order to define the relationship between disability, pain intensity, therapeutical responsiveness and the presence of PLMd. Results In the migraineurs children group, the individuals with PLM pathological index (PLMI ≥ 5) represent the 26.47% of sample and present higher frequency (p < 0.001), intensity (p < 0.001), duration (p = 0.006) and life impairment as scored in the PedMIDAS (p < 0.001) of headache and lower efficacy of prophylactic (p = 0.001) and acute (p = 0.006) pharmacological treatment than MoA children without PLM pathological index. Conclusions This preliminary study indicates the potential value of the determination of the PLMd signs, and the importance of the PSG evaluation in children affected by migraine, particularly when the clinical and pharmacological management tend to fail in the attacks control. PMID:23815623

  10. Trends in scientific activity addressing transmissible spongiform encephalopathies: a bibliometric study covering the period 1973–2002

    PubMed Central

    Sanz-Casado, Elías; Ramírez-de Santa Pau, Margarita; Suárez-Balseiro, Carlos A; Iribarren-Maestro, Isabel; de Pedro-Cuesta, Jesús

    2006-01-01

    Background The purpose of this study is to analyse the trends in scientific research on transmissible spongiform encephalopathies by applying bibliometric tools to the scientific literature published between 1973 and 2002. Methods The data for the study were obtained from Medline database, in order to determine the volume of scientific output in the above period, the countries involved, the type of document and the trends in the subject matters addressed. The period 1973–2002 was divided in three sub-periods. Results We observed a significant growth in scientific production. The percentage of increase is 871.7 from 1973 to 2002. This is more evident since 1991 and particularly in the 1996–2001 period. The countries found to have the highest output were the United States, the United Kingdom, Japan, France and Germany. The evolution in the subject matters was almost constant in the three sub-periods in which the study was divided. In the first and second sub-periods, the subject matters of greatest interest were more general, i.e Nervous system or Nervous system diseases, Creutzfeldt-Jakob disease, Scrapie, and Chemicals and Drugs, but in the last sub-period, some changes were observed because the Prion-related matters had the greatest presence. Collaboration among authors is small from 1973 to 1992, but increases notably in the third sub-period, and also the number of authors and clusters formed. Some of the authors, like Gajdusek or Prusiner, appear in the whole period. Conclusion The study reveals a very high increase in scientific production. It is related also with the beginnings of research on bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease, with the establishment of progressive collaboration relationships and a reflection of public health concerns about this problem. PMID:17026743

  11. Orbital period studies of the two contact binaries TZ Bootis and Y Sextantis

    NASA Astrophysics Data System (ADS)

    Qian, S.; Liu, Q.

    2000-03-01

    The physical properties of the two A-type contact binaries TZ Boo and Y Sex are nearly the same. In the present paper, many of their published times of light minima are collected and the changes in their orbital periods are analyzed. It is indicated that the orbital period of TZ Boo shows several alternating jumps while it undergoes a secular decrease of -11.8x10-8 days/year. Several random jumps superposed on a secular decrease (-5.5x10-8 days/year) are also found in the period of Y Sex. The secular decrease is usually interpreted as mass transfer from the more to the less massive components, or mass and angular momentum loss (AML) from the systems. According to the AML theory, on the contact stage, the orbital AML is mainly caused by the mass transfer from the less to the more massive component and the mass ratio decreasing and orbital period gradually increasing are the corresponding results. The extremely low mass ratio and orbital angular momentum of the two systems show that they are evolved via AML and the present secular decrease in the periods may suggest that the magnetic activity in the two systems are very strong. The relation between the changes of the orbital periods and the magnetic activity in the two systems are discussed. We think that the interplay between the variable AML and variable magnetic coupling can explain both the jumps and secular decrease in the orbital periods of the two systems. Table~2 and Table~4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strabg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  12. A study of coronal X-ray emission from short-period Algol binaries

    NASA Technical Reports Server (NTRS)

    Singh, K. P.; Drake, S. A.; White, N. E.

    1995-01-01

    A study of X-ray emission from five short-period Algol-type binaries based on observations with Advanced Satellite for Cosmology and Astrophysics (ASCA) and ROSAT is presented. We have observed RZ Cas with both satellites, and beta Per, U Cep, delta Lib, and TW Dra with ROSAT. Significant intensity variations are seen in the X-ray emission from RZ Cas, U Cep, TW Dra, and delta Lib. These variations seem unrelated to the eclipsing behavior of these systems and are probably due to either rotational modulation of compact active regions on the surfaces of the chromospherically active secondary components or to flaring activity in the systems. The spectra of all but one of the systems require the presence of at least two discrete plasma components with different temperatures (0.6 - 0.7 keV, and approximately 2 keV) and the abundances of the medium-Z elements 20% - 50% of the solar photospheric values. The high resolving power and signal-to-noise ratio of the ASCA spectra allow us to individually constrain the coronal abundances of O, Ne, Mg, Si, S, and Fe in RZ Cas. We demonstrate that, if we use the elemental abundances and temperatures obtained from the analysis of their ASCA spectra as (fixed) inputs, to fit the ROSAT PSPC spectra well requires the presence of a third component (kT approximately 0.2 - 0.3 keV) in RZ Cas and beta Per. A continuous emission measure model of the power-law type (EM(T) variesas (T/T(sub max)(sup alpha)) generally gives a poor fit to the ASCA and ROSAT data on most sources. Circumstellar or circumbinary absorbing matter seems to be present in some of these systems, as indicated by the variable total column density needed to fit their X-ray spectra.

  13. Study of multi-periodic coronal pulsations during an X-class solar flare

    NASA Astrophysics Data System (ADS)

    Chowdhury, Partha; Srivastava, A. K.; Dwivedi, B. N.; Sych, Robert; Moon, Y.-J.

    2015-12-01

    We investigate quasi-periodic coronal pulsations during the decay phase of an X 3.2 class flare on 14 May 2013, using soft X-ray data from the RHESSI satellite. Periodogram analyses of soft X-ray light curves show that ∼ 53 s and ∼ 72 s periods co-exist in the 3-6 keV, 6-12 keV and 12-25 keV energy bands. Considering the typical length of the flaring loop system and observed periodicities, we find that they are associated with multiple (first two harmonics) of fast magnetoacoustic sausage waves. The phase relationship of soft X-ray emissions in different energy bands using cross-correlation technique show that these modes are standing in nature as we do not find the phase lag. Considering the period ratio, we diagnose the local plasma conditions of the flaring region by invoking MHD seismology. The period ratio P1/2P2 is found to be ∼ 0.65, which indicates that such oscillations are most likely excited in longitudinal density stratified loops.

  14. A study on periodic solutions for the circular restricted three-body problem

    SciTech Connect

    Gao, F. B.; Zhang, W. E-mail: gaofabao@gmail.com

    2014-12-01

    For the circular restricted three-body problem (CR3BP) in the inertial frame, we interpret the fact that there is no non-trivial 2π-periodic solution of the problem's homogeneous system. Furthermore, based on Reissig's theory, the existence of periodic solutions for the CR3BP is proved rigorously by using the above fact in conjunction with an a priori estimate. It is significant that the existence of periodic solutions of the CR3BP is mainly influenced by factors such as initial values, primary masses, and selection of the problem's control function. In addition, it is notable that the analytic proof of Poincaré's first class solutions is addressed for all values of the mass parameter in the interval (0, 1), the value of which must be sufficiently small according to previously published literature.

  15. [Study on ammonia-N degradation monitoring by analyzing long-period fiber grating spectrum character].

    PubMed

    Liu, Hong-yue; Liang, Da-kai; Zeng, Jie; Cao, Zhi-bin; Zeng, Jian-min

    2010-09-01

    In the present paper, the principle of a long-period fiber grating (LPFG) ammonia-nitrogen degradation monitoring sensor was discussed in detail firstly based on a sensitive characteristic that the resonance spectrum of long-period fiber grating changes with refractive index in external environment. The relationship between the resonance peaking wavelength of long-period fiber grating and the concentration of ammonia-nitrogen solutions was also analyzed detailedly. Then, the long-period fiber grating spectrum measurement technology was selected to obtain long-period fiber grating spectrum curves corresponding to seven different kinds of concentration of ammonia-nitrogen solutions, and the resonance wavelengths increased with the increase in the concentration of ammonia-nitrogen solutions. The variations of the resonance wavelength decreased from 2.707 to 0.068 nm and had a relatively good corresponding relationship with the concentration values of ammonia-nitrogen solutions. The responsivity of this correlation is 52.78 pm x mg(-1) x L. The concentration of ammonia-nitrogen solutions was acquired exactly through the way of monitoring the changes of the spectrum attribute, at the same time, the process and the extent of ammonia-nitrogen wastewater degradation were estimated. This method, which can directly monitor the concentration of ammonia-nitrogen solutions, is simple and easy to operate. The measurement and transmission section of the system are completely composed of optical fiber, which can avoid the electronic interference. There is no necessary to use chemic reagent to sign the solutions, which are going to be degraded. In conclusion, the late-model long-period fiber grating ammonia-nitrogen degradation monitoring system could achieve a real time, rapid, accurate and long distance measurement.

  16. It's T time: A study on the return period of multivariate problems

    NASA Astrophysics Data System (ADS)

    Michailidi, Eleni Maria; Balistrocchi, Matteo; Bacchi, Baldassare

    2016-04-01

    One of the most important tasks a hydrologist must face is the proper estimation of the 'design values' of a natural variable corresponding to a given Return Period, T, of failures of the hydraulic 'structure' to be designed or verified. Sometimes the 'structure' is simply the embankments, the failure of which corresponds to the outflows of flood runoff on the surrounding land. The widely adopted definition of T, in a problem regarding the maxima of hydrological variables, is "the average time elapsing between two successive occurrences of an event exceeding a certain magnitude of the natural variables". If T is referred to the minima, the symmetric definition pertains to the "average time between two periods during which the variable ranges below a given magnitude". Conventional (and the only accepted) approaches for estimation of T involve a single natural variable (i.e. flood-peak of a river at a given cross section, the daily maximum discharge, the maximum daily rainfall depth observed at a given rain-gauge). The method of estimation of T entails a frequency analysis of the variable of interest, where the design value of a given T is needed to design the structure of interest (e.g. dams, sewers). In other words, T is used as the index value to set the assigned risk level for the hydraulic works. However, a univariate approach in complex problems ignores the effect of significant variables interrelation leading to different risk levels for each quantity of interest and resulting in a completely wrong estimate of the risk. For example, if one considers the flood inflow in a lake around which cities and villages are positioned, the variable to be investigated in relation to the risk assessment is the lake water level. It is obvious that the same water level may occur from very different flood hydrographs, even when the same initial water level and the same rate curve of outflows are considered. This is a consequence of the interaction of at least three joint

  17. Experimental Study of Tip Vortex Flow from a Periodically Pitched Airfoil Section

    NASA Technical Reports Server (NTRS)

    Zaman, Khairul; Fagan, Amy; Mankbadi, Mina

    2016-01-01

    An experimental investigation of tip vortex flow from a NACA0012 airfoil, pitched periodically at various frequencies, is conducted in a low-speed wind tunnel. Initially, data for stationary airfoil held fixed at various angles-of-attack are gathered. Flow visualization pictures as well as detailed cross-sectional properties areobtained at various streamwise locations using hot-wire anemometry. Data include mean velocity, streamwise vorticity as well as various turbulent stresses. Preliminary data are also acquired for periodically pitched airfoil. These results are briefly presented in this extended abstract.

  18. Behavioral study of ultradian activity periods of mice enclosed in experimental cages of different dimensions

    NASA Technical Reports Server (NTRS)

    Guillot, A.

    1982-01-01

    Male mice are enclosed in cages of different dimensions (cage A - 23x8x8 cm., cage B - 36x27x17 cm.), in an alternating light/dark regimen, at an ambient temperature of 22 to 23 C. The successions of the behavioral sequences of ultradian activity periods are noticed by direct observation during 11 consecutive hours in light. The experimental situation modifies the mean duration time and the behavioral organization of each activity period. However, the comparison of the overall activity time lengths and the comparison of the overall behavioral frequencies suggest that the energy spent per mouse is constant.

  19. 39 CFR 3050.12 - Obsolescence of special studies relied on to produce the Postal Service's annual periodic reports...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Obsolescence of special studies relied on to... studies relied on to produce the Postal Service's annual periodic reports to the Commission. The Postal Service shall provide a list of special studies whose results are used to produce the estimates in...

  20. The relation between prepregnancy sexuality and sexual function during pregnancy and the postpartum period: a prospective study.

    PubMed

    Yıldız, Hatice

    2015-01-01

    This study examined the relation between sexual functions of women in prepregnancy (before conception) and during pregnancy and the postpartum period. This study was conducted on 59 healthy pregnant women. Participants were followed from the eighth week of gestation to 6 months after delivery. Sexual function during pregnancy and the postpartum period was shown to have a significant linear correlation with prepregnancy sexuality. There was no relation between pregnancy and postpartum sexuality. All of the participants who had prepregnancy sexual dysfunction continued to experience it during pregnancy, and the majority of them had a significant level of sexual dysfunction in the postpartum period. Our results showed that prepregnancy sexuality plays an important role in maintaining sexuality during pregnancy and the postpartum period.

  1. The superacid HBr/AlBr(3) : protonation of benzene and ordered crystal structure of [C(6)H(7)](+)[Al(2)Br(7)](-).

    PubMed

    Scholz, Franziska; Himmel, Daniel; Eisele, Lea; Unkrig, Wiebke; Krossing, Ingo

    2014-02-03

    Crystalline and properly ordered protonated benzene as the [C6 H7 ](+) [Al2 Br7 ](-) ⋅(C6 H6 ) salt 1 are obtained by the combination of solid AlBr3 , benzene, and HBr gas. Compound 1 was characterized and verified by NMR, Raman and X-Ray spectroscopy. This unexpected simple and straight forward access shows that HBr/AlBr3 is an underestimated superacid that should be used more frequently.

  2. Vibrational spectra of Cs2Cu(SO4)2·6H2O and Cs2Cu(SeO4)2·nH2O (n = 4, 6) with a crystal structure determination of the Tutton salt Cs2Cu(SeO4)2·6H2O

    NASA Astrophysics Data System (ADS)

    Wildner, M.; Marinova, D.; Stoilova, D.

    2016-02-01

    The solubility in the three-component systems Cs2SO4-CuSO4-H2O and Cs2SeO4-CuSeO4-H2O have been studied at 25 °C. The experimental results show that double salts, Cs2Cu(SO4)2·6H2O and Cs2Cu(SeO4)2·4H2O, crystallize from the ternary solutions within large concentration ranges. Crystals of Cs2Cu(SeO4)2·6H2O were synthesized at somewhat lower temperatures (7-8 °C). The thermal dehydration of the title compounds was studied by TG, DTA and DSC methods and the respective dehydration schemes are proposed. The calculated enthalpies of dehydration (ΔHdeh) have values of: 434.2 kJ mol-1 (Cs2Cu(SeO4)2·6H2O), 280.9 kJ mol-1 (Cs2Cu(SeO4)2·4H2O), and 420.2 kJ mol-1 (the phase transition of Cs2Cu(SO4)2·6H2O into Cs2Cu(SO4)2·H2O). The crystal structure of Cs2Cu(SeO4)2ṡ6H2O was determined from single crystal X-ray diffraction data. It belongs to the group of Tutton salts, crystallizing isotypic to the respective sulfate in a monoclinic structure which is characterized by isolated Cu(H2O)6 octahedra and SeO4 tetrahedra, interlinked by hydrogen bonds and [9]-coordinated Cs+ cations. Infrared spectra of the cesium copper compounds are presented and discussed with respect to both the normal modes of the tetrahedral ions and the water molecules. The analysis of the infrared spectra of the double compounds reveals that the distortion of the selenate tetrahedra in Cs2Cu(SeO4)2·4H2O is stronger than those in Cs2Cu(SeO4)2·6H2O in agreement with the structural data. Matrix-infrared spectroscopy was applied to confirm this claim - Δν3 for SO4 2 - ions matrix-isolated in Cs2Cu(SeO4)2·6H2O has a value of 35 cm-1 and that of the same ions included in Cs2Cu(SeO4)2·4H2O - 84 cm-1. This spectroscopic finding is due to the formation of strong covalent bands Cu-OSO3 on one hand, and on the other to the stronger deformation of the host SeO4 2 - tetrahedra in Cs2Cu(SeO4)2·4H2O as compared to those in Cs2Cu(SeO4)2·6H2O. The strength of the hydrogen bonds as deduced from the

  3. Orbital Period Variation Study of the Algol Eclipsing Binary DI Pegasi

    NASA Astrophysics Data System (ADS)

    Hanna, M. A.; Amin, S. M.

    2013-08-01

    We discuss the orbital period changes of the Algol semi-detached eclipsing binary DI Peg by constructing the (O-C) residual diagram via using all the available precise minima times. We conclude that the period variation can be explained by a sine-like variation due to the presence of a third body orbiting the binary, together with a long-term orbital period increase ( dP/dt=0.17 sec/century) that can be interpreted to be due to mass transfer from the evolved secondary component (of rate 1.52×10^{-8} M_{⊙}/ yr) to the primary one. The detected low-mass third body (M_{3 min.}=0.22±0.0006 M_{⊙}) is responsible for a periodic variation of about 55 years light time effect. We have determined the orbital parameters of the third component which show a considerable eccentricity e_{3}= 0.77±0.07 together with a longitude of periastron ω_{3}=300° ± 10°.

  4. Comparative Study of Periodical Literature Indexing: Print versus Electronic Access. Final Report.

    ERIC Educational Resources Information Center

    Lowry, Charles B.

    This 2-year project at the University of Texas at Arlington (UTA) was conducted to determine the feasibility of providing online periodical indexing to the journal holdings of the UTA libraries by demonstrating an extended use of the libraries' NOTIS Online Public Access Catalog (OPAC) to provide better access to local resources. Three approaches…

  5. Period studies and photometric models for two EB-type binaries EU Hya and AW Vul

    NASA Astrophysics Data System (ADS)

    Yang, Yuan-Gui; Li, Qun; Li, Hua-Li; Dai, Hai-Feng

    2016-02-01

    New photometry for two Algol-type binaries, EU Hya (P = 0.7782 d) and AW Vul (P = 0.8065 d), was carried out using the 60-cm telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, photometric elements were derived from the multi-color light curves. The modeled results indicate that the two systems are near-contact binaries, whose secondary components fill their Roche lobes. The fill-out factors of the primaries are fp = 81.2 (±0.2)% for EU Hya and fp = 82.4 (±0.3)% for AW Vul. Period analysis implies that there exists a downward parabola with a light-time orbit from the (O - C) curve. This kind of periodic oscillation may be attributed to the light-time orbit effect of a third companion. The long-term period decrease may be caused by mass and angular momentum loss. When the orbital period decreases, the fill-out factor of fp will increase. Our results indicate that the primaries will also eventually fill their Roche lobes. EU Hya and AW Vul may possibly evolve from semi-detached binaries into contact ones.

  6. A Case Study of Periodical Use by Library and Information Science Students

    ERIC Educational Resources Information Center

    Ivins, Tammy

    2013-01-01

    There is a lack of information in the literature about the sources used for research by modern Master of Library and Information Science students in the United States, and so the objective of this project is to understand the use of periodical articles by these students. Specifically: do articles play a major role in student research, how current…

  7. Density functional calculations for a high energy density compound of formula C6H 6-n (NO 2) n.

    PubMed

    Chi, Wei-Jie; Li, Lu-Lin; Li, Bu-Tong; Wu, Hai-Shun

    2012-08-01

    A series of polynitroprismanes, C(6)H(6-n )(NO(2))(n) (n = 1-6) intended for use as high energy density compounds (HEDCs) were designed computationally. Their electronic structures, heats of formation, interactions between nitro groups, specific enthalpies of combustion, bond dissociation energies, and explosive performances (detonation velocities and detonation pressures) were calculated using density functional theory (DFT) with the 6-311 G** basis set. The results showed that all of the polynitroprismanes had high positive heats of formation that increased with the number of substitutions for the prismane derivatives, while the specific enthalpy of combustion decreased as the number of nitro groups increased. In addition, the range of enthalpy of combustion reducing is getting smaller. Interactions between ortho (vicinal) groups deviate from the group additivity rule and decrease as the number of nitro groups increases. In terms of thermodynamic stability, all of the polynitroprismanes had higher bond dissociation energies (BDEs) than RDX and HMX. Detonation velocities and detonation pressures were estimated using modified Kamlet-Jacobs equations based on the heat of detonation (Q) and the theoretical density of the molecule (ρ). It was found that ρ, D, and P are strongly linearly related to the number of nitro groups. Taking both their energetic properties and thermal stabilities into account, pentanitroprismane and hexanitroprismane are potential candidate HEDCs.

  8. Coupled antiferromagnetic spin- 12 chains in green dioptase Cu6[Si6O18]·6H2O

    DOE PAGES

    Podlesnyak, Andrey A; Larry M. Anovitz; Kolesnikov, Alexander I; ...

    2016-02-01

    Inmore » this paper, we report inelastic neutron scattering measurements of the magnetic excitations of green dioptase Cu6[Si6O18]∙6H2O. The observed spectrum contains two magnetic modes and a prominent spin gap that is consistent with the ordered ground state of Cu moments coupled antiferromagnetically in spiral chains along the c axis and ferromagnetically in ab planes on the hexagonal cell. The data are in excellent agreement with a spin- 12Hamiltonian that includes antiferromagnetic nearest-neighbor intrachain coupling Jc=10.6(1) meV, ferromagnetic interchain coupling Jab=₋1.2 (1) meV, and exchange anisotropy ΔJc=0.14(1) meV. We calculated the sublattice magnetization to be strongly reduced, ~0.39μB. This appears compatible with a reduced Néel temperature, TN=14.5K

  9. The observation of scintillation in a hydrated inorganic compound: CeCl3 6H2O

    SciTech Connect

    Boatner, Lynn A; Neal, John S; Ramey, Joanne Oxendine; Chakoumakos, Bryan C; Custelcean, Radu

    2013-01-01

    We have recently reported the discovery of a new family of rare-earth metal-organic single-crystal scintillators based on Ce3+ as the activator ion. Starting with the CeCl3(CH3OH)4 prototype, this family of scintillators has recently been extended to include complex metal-organic adducts produced by reacting CeCl3 with heavier organics (e.g., isomers of propanol and butanol). Some of these new rare-earth metal-organic materials incorporated waters of hydration in their structures, and the observation of scintillation in these hydrated compounds was an original finding for any solid scintillator. In the present work, we now report what is apparently the initial observation of gamma-ray-excited scintillation in an inorganic hydrated material, namely single-crystal monoclinic CeCl3 6H2O. This observation shows that the mechanisms of the various scintillation energy-transfer processes are not blocked by the presence of waters of hydration in an inorganic material and that the observation of scintillation in other hydrated inorganic compounds is not precluded.

  10. Period04 FCAPT uvby Photometric Studies of Eight Magnetic CP Stars

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.; Dukes, Robert J.

    2014-06-01

    We present Four College Automated Photometric Telescope (FCAPT) differential Stromgren uvby photometry of 8 magnetic CP (mCP) stars: HD 5797 (V551 Cas), HD 26792 (DH Cam), HD 27309 (56 Tau, V724 Tau), HD 49713 (V740 Mon), HD 74521 (49 Cnc, BI Cnc), HD 120198 (84 UMa, CR UMa), HD 171263 (QU Ser), and HD 215441 (GL Lac, Babcock's star). Our data sets are larger than those of most mCP stars in the literature. These are the first FCAPT observations of HD 5797, HD 26792, HD 49713, and HD 171263. Those for the remaining four stars substantially extend published FCAPT data. The FCAPT observed some stars for a longer time range and with greater accuracy than other optical region automated photometric telescopes.Our goals were to determine very accurate periods, the u, v, b, and y amplitudes, and if there were any long period periods. In addition we wanted to compare our results with those of magnetic field measurements to help interpret the light curves.We used the Period04 computer program to analyze the light curves. This program provides errors for the derived quantities as it fits the light curve. Our derived periods of 68.046 +/- 0.008 days for HD 5797, 3.80205 +/- 0.00006 days for HD 26792, 1.56889 +/- 0.000002 days for HD 27309, 2.13536 +/- 0.00002 days for HD 49713, 7.0505 +/- 0.0001 days for HD 74521, 1.38577 +/- 0.000004 days for HD 120198, 3.9974 +/- 0.0001days for HD 171263, and 9.487792 +/- 0.00005 days for HD 215441 are refinements of the best determinations in the literature.

  11. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mössbauer spectroscopy

    SciTech Connect

    Diallo, M. L.; Fnidiki, A. Lardé, R.; Cuvilly, F.; Blum, I.; Lechevallier, L.; Debelle, A.; Thomé, L.; Viret, M.; Marteau, M.; Eyidi, D.; Declémy, A.

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mössbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  12. Human comfort studies in Debrecen regarding the 2006-2008 period

    NASA Astrophysics Data System (ADS)

    Gyarmati, R.; Toth, T.; Szegedi, S.; Kapocska, L.

    2010-09-01

    Human comfort studies in Debrecen regarding the 2006-2008 period Renata Gyarmati, Tamas Toth, Sandor Szegedi and Laszlo Kapocska University of Debrecen Department of Meteorology, 4032 Debrecen Egyetem tér 1. The significance of human meteorological studies, primarily the importance of observing the sensitivity to fronts has been verified by several foreign and native authors. However, this field of research has shown few exact scientific achievements so far, but the understanding of the connection between weather and human comfort could be promotive factor of human health preservation. This project is quite current since a great part of so called ‘healthy people', who are not suffered from constant diseases are sorely tried by the changing weather. Frequent occurrence of extreme meteorological events will increase the number of meteoropathies in the near future. The whole living world is sensitive to changes in temperature, pressure, humidity and wind speed caused by meteorological events. Frequent fluctuations cause a great trial to pregnant women. The presence of the contact between weather and obstetrical events, formerly proved by Raics (1972), Nowinszky-Nowinszky (1996-1997), Puskás (2008) is supported by our examined data from the University of Debrecen Medical School and Health Science Centre Department of Obstetrics and Gynaecology. During our observation we scrutinized the relation between frontal passage macrosynoptic types and birth number. It's evident that higher data of birth number can be observed during on-coming weather fronts. In case of resident warm fronts, contrast with free-from-front days increasing values can't be experienced although an increase can be observed at the other front types. In the mentioned term over the change of pressure a significant change in temperature probably produced an effect on start of labours. This is in harmony with macrosynoptic types applied to the Carpathian basin. According to this, higher birth number was

  13. Optical spectra, electronic structure and aromaticity of benzannulated N-heterocyclic carbene and its analogues of the type C6H4(NR)2E: (E = Si, Ge, Sn, Pb).

    PubMed

    Aysin, Rinat R; Bukalov, Sergey S; Leites, Larissa A; Zabula, Alexander V

    2017-02-24

    A series of benzannulated N-heterocyclic compounds containing divalent 14 group atoms, C6H4(NR)2E(II), E = C, Si, Ge, Sn, Pb, have been studied by various experimental (vibrational and UV-vis spectroscopy) and theoretical (NICS, ISE, ACID) techniques. The methods used confirm 10 π-electron delocalization (aromaticity) in these heterocycles, however, the aromaticity sequences estimated by the criteria based on different physical properties do not coincide.

  14. Damaging events along roads during bad weather periods: a case study in Calabria (Italy)

    NASA Astrophysics Data System (ADS)

    Petrucci, O.; Pasqua, A. A.

    2012-02-01

    The study focuses on circumstances that affect people during periods of bad weather conditions characterised by winds, rainfall, landslides, flooding, and storm surges. A methodological approach and its application to a study area in southern Italy are presented here. A 10-yr database was generated by mining data from a newspaper. Damaging agents were sorted into five types: flood, urban flooding, landslide, wind, and storm surge. Damage to people occurred in 126 cases, causing 13 victims, 129 injured and about 782 people involved but not injured. For cases of floods, urban flooding and landslides, the analysis does not highlight straightforward relationships between rainfall and damage to people, even if the events showed different features according to the months of occurrence. The events occurring between May and October were characterised by concentrated and intense rainfall, and between May and July, the highest values of hourly (103 mm on the average) and monthly rainfall (114 mm on the average) were recorded. Urban flooding and flash floods were the most common damaging agents: injured, involved people and more rarely, cases with victims were reported. Between November and April, the highest number of events was recorded. Rainfall presented longer durations and hourly and sub-hourly rainfall were lower than those recorded between May and October. Landslides were the most frequent damaging agents but the highest number of cases with victims, which occurred between November and January, were mainly related to floods and urban flooding. Motorists represent the totality of the victims; 84% of the people were injured and the whole of people involved. All victims were men, and the average age was 43 yr. The primary cause of death was drowning caused by floods, and the second was trauma suffered in car accidents caused by urban flooding. The high number of motorists rescued in submerged cars reveals an underestimation of danger in the case of floods, often

  15. Indoor radon periodicities and their physical constraints: a study in the Coimbra region (Central Portugal).

    PubMed

    Neves, L J P F; Barbosa, S M; Pereira, A J S C

    2009-10-01

    Indoor radon activities were measured during a period of 6 months, as well as several physical environmental variables (temperature, pressure, humidity and rainfall). The location was a small room at an administrative building of the University of Coimbra, usually undisturbed by human activities and situated over bedrock of low-uranium Triassic red sandstones. A low average activity of radon was observed (36 Bq m(-3)), however showing a very well marked daily periodicity (10+/-5 Bq m(-3)), with maximum values occurring more frequently between 9 and 10 a.m. Daily variations are shown to have no relation with earth tides, and their amplitudes exhibit a significant correlation with outdoor temperature; no dependence on barometric pressure was found. Rainfall disturbs the observed daily radon cycles through a strong reduction of their amplitude, but has no effect on the long-term variability of the gas concentration.

  16. Evolution of illustrations in anatomy: a study from the classical period in Europe to modern times.

    PubMed

    Ghosh, Sanjib Kumar

    2015-01-01

    Illustrations constitute an essential element of learning anatomy in modern times. However it required a significant evolutionary process spread over centuries, for illustrations to achieve the present status in the subject of anatomy. This review article attempts to outline the evolutionary process by highlighting on the works of esteemed anatomists in a chronological manner. Available literature suggests that illustrations were not used in anatomy during the classical period when the subject was dominated by the descriptive text of Galen. Guido da Vigevano was first to use illustrations in anatomy during the Late Middle Ages and this concept developed further during the Renaissance period when Andreas Vesalius pioneered in illustrations becoming an indispensable tool in conveying anatomical details. Toward later stages of the Renaissance period, Fabricius ab Aquapendente endeavored to restrict dramatization of anatomical illustrations which was a prevalent trend in early Renaissance. During the 18th century, anatomical artwork was characterized by the individual styles of prominent anatomists leading to suppression of anatomical details. In the 19th century, Henry Gray used illustrations in his anatomical masterpiece that focused on depicting anatomical structures and were free from any artistic style. From early part of the 20th century medical images and photographs started to complement traditional handmade anatomical illustrations. Computer technology and advanced software systems played a key role in the evolution of anatomical illustrations during the late 20th century resulting in new generation 3D image datasets that are being used in the 21st century in innovative formats for teaching and learning anatomy.

  17. Influence of harvest method and period on olive oil composition: an NMR and statistical study.

    PubMed

    D'Imperio, Marco; Gobbino, Marco; Picanza, Antonio; Costanzo, Simona; Della Corte, Anna; Mannina, Luisa

    2010-10-27

    The influence of harvest period and harvest method on olive oil composition was investigated by nuclear magnetic resonance (NMR) spectroscopy and by some quality parameters such as free acidity, peroxide value, and UV spectrophotometric indices. This work focuses on two secondary factors (harvest period and harvest method) and investigated their interactions with primary (genetic and pedoclimatic) and secondary (agronomic practices and technological procedures) factors. To avoid misinterpretation, the general linear model analysis (GLM) was used to adjust the result obtained from the analysis of variance (ANOVA). In this way, the effect of the factor of interest was corrected for the effects of the other factors that might influence the variable under investigation. The weight of each factor was evaluated by the variance component analysis (VCA). Finally, multivariate statistical analyses, namely, principal component analysis (PCA) and linear discriminant analysis (LDA), were applied. Samples were grouped according to the harvest period and harvest method. Volatile compounds, that is, hexanal and trans-2-hexenal, as well as the sn-1,3-diglycerides and squalene, significantly decreased during the ripening. The relative value of the ΔK parameter and the hexanal amount were higher in the olive oils obtained from olives harvested by one type of hand-held machine (shaker), whereas the unsaturated fatty chains in the olive oils were higher when another type (comb) was used.

  18. A Comparison of Two CD-ROM Periodical Indexes for Use in the Middle School. A Scholarly Study.

    ERIC Educational Resources Information Center

    Thrash, Beverly M.

    This purpose of this study was to determine which periodical index--InfoTrac or EBSCO Magazine Article Summaries--is the most appropriate for use by middle school students preparing required research projects. The study population consisted of randomly selected sixth, seventh, and eighth grade students (N=50) in a Cobb County (Georgia) middle…

  19. Determination of the structural properties of the aqueous electrolyte LiCl6H 2 O at the supercooled state using the Reverse Monte Carlo (RMC) simulation

    NASA Astrophysics Data System (ADS)

    ZIANE, M.; HABCHI, M.; DEROUICHE, A.; MESLI, S. M.; BENZOUINE, F.; KOTBI, M.

    2017-03-01

    A structural study of an aqueous electrolyte whose experimental results are available. It is a solution of A structural study of an aqueous electrolyte whose experimental results are available. It is a solution LiCl6H 2 O type at supercooled state (162K) contrasted with pure water at room temperature by means of Partial Distribution Functions (PDF) issue from neutron scattering technique. The aqueous electrolyte solution of the chloride lithium LiCl presents interesting properties which is studied by different methods at different concentration and thermodynamical states: This system possesses the property to become a glass through a metastable supercooled state when the temperature decreases. Based on these partial functions, the Reverse Monte Carlo method (RMC) computes radial correlation functions which allow exploring a number of structural features of the system. The purpose of the RMC is to produce a consistent configuration with the experimental data. They are usually the most important in the limit of systematic errors (of unknown distribution).

  20. Pyrolysis of Tropyl Radical (C7H7) and Benzyl Radical (C6H5CH2) in a Heated Micro-Reactor

    NASA Astrophysics Data System (ADS)

    Buckingham, Grant; Ellison, Barney; Porterfield, Jessica P.; Daily, John W.; Ahmed, Musahid; Robichaud, David; Nimlos, Mark R.

    2016-06-01

    Benzyl radical (C6H5CH2) is a crucial intermediate in the combustion and pyrolysis of substituted aromatic species that are common both in modern gasoline and potential future biofuels. The decomposition of benzyl radical is complicated and has been shown by isotopic labeling to require interesting isomerizations pathways. To better understand these pathways, a set of C7H7 radicals has been studied in a heated micro-reactor. Through multiple experiments, it has be shown that benzyl radical and cycloheptatrienyl (tropyl) radical (c-C7H7) do not interconvert, even at temperatures where both have completely thermally decomposed. To confirm this, tropyl radical has been studied directly and its pyrolysis is quite simple, only cyclopentadienyl radical (c-C5H5) and acetylene (HCCH) are formed. Cyclopentadienyl radical then decomposes to acetylene and propargyl radical (HCCCH2). These products have all been identified through use of tunable synchrotron radiation by confirming their respective photoionization spectra. Matrix isolation infrared (IR) spectroscopy has also been used to identity these products. A previously unanswered question in benzyl radical decomposition has been addressed by studying the pyrolysis of 2,5-norbornadiene, which indicates benzyl radical may decompose through a norbornadiene-like bicyclic radical intermediate. This pathways successfully predicts the correct isotopically labeled products observed previously during 13C labeled benzyl pyrolysis.

  1. Influence of the energy parameters of the deposited laser-induced flow of platinum atoms on characteristics of a Pt/n-6H-SiC thin-film structure

    SciTech Connect

    Fominskii, V. Yu. Romanov, R. I.; Gnedovets, A. G.; Zuev, V. V.; Demin, M. V.

    2010-04-15

    The features of platinum film formation on n-6H-SiC substrates were experimentally studied for different methods of pulsed laser deposition, i.e., by both the conventional method in vacuum and in an inert gas atmosphere. In the latter case, a disk screen was placed on the plume expansion axis between the laser target and substrate to protect the latter from micrometer and submicrometer particles. A numerical model of such a process was developed, which makes it possible to predict the deposited film distribution over the substrate surface, energy and angular parameters of the atomic flow as laser plume properties, inert gas pressure, and screen position are varied. Simulation results were used to explain electrical properties of Pt/n-6H-SiC thin-film structures fabricated by different methods.

  2. Photophysical properties of ESIPT inspired fluorescent 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and its derivative: Experimental and DFT based approach

    NASA Astrophysics Data System (ADS)

    Deshmukh, Mininath S.; Sekar, Nagaiyan

    2015-01-01

    The excited-state intramolecular proton transfer chromophores 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and 2-(4-(diethylamino)-2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione are synthesized from 4,5-diamino-N-methylphthalimide. The photophysical behavior of the synthesized chromophores was studied using UV-visible and fluorescence spectroscopy in the polar and non-polar solvents. The synthesized o-hydroxyphenyl benzimidazole derivatives are fluorescent and very sensitive to the solvent polarity. These dyes are thermally stable up to 317 °C. Density Functional Theory computations have been used to understand the structural, molecular, electronic and photophysical properties of the chromophores. The experimental absorption and emission wavelengths are in good agreement with the computed vertical excitation and theoretical emission obtained by Density Functional Theory and Time Dependant Density Functional Theory.

  3. Bioengineering studies of periodic external compression as prophylaxis against deep vein thrombosis-part I: numerical studies.

    PubMed

    Kamm, R D

    1982-05-01

    This paper presents the results of a numerical study of the technique of periodic external compression for the prevention of deep vein thrombosis. In the model the veins of the lower leg are portrayed as a continuous system rather than as discrete elements as in previous models. Consequently, we are able to explore the detailed effects of different modes of compression including (i) uniform compression, the simultaneous application of uniform pressure over the entire lower leg, (ii) graded compression, the application of nonuniform pressure, maximum at the ankle and minimum at the knee, and (iii) wavelike compression, a wave of compression proceeding from the ankle toward the knee. These numerical results indicate that the effectiveness of uniform compression is severely compromised by the formation of a flow-limiting throat at the proximal end of the compression cuff that reduces both the rate at which blood is discharged from the lower leg and the total blood volume removed. Both of these detrimental effects can be avoided by the use of either wavelike of graded compression. Both alternated methods are shown to produce more uniform augmentation of volume flow rate, flow velocity and shear stress, throughout the entire lower leg. In the companion paper, Part II [18] (see following article), these same compression modes are tested using a simple hydraulic model consisting of a single latex tube inside a foam cylinder as a highly simplified representation of a human leg.

  4. A numerical study of transition control by periodic suction-blowing

    NASA Technical Reports Server (NTRS)

    Biringen, Sedat

    1987-01-01

    The applicability of active control of transition by periodic suction-blowing is investigated via direct numerical simulations of the Navier-Stokes equations. The time-evolution of finite-amplitude disturbances in plane channel flow is compared in detail with and without control. The analysis indicates that, for relatively small three dimensional amplitudes, a two dimensional control effectively reduces disturbance growth rates even for linearly unstable Reynolds numbers. After the flow goes through secondary instability, three dimensional control seems necessary to stabilize the flow. An investigation of the temperature field suggests that passive temperature contamination is operative to reflect the flow dynamics during transition.

  5. Breaking inertia: increasing access to journals during a period of declining budgets: a case study

    PubMed Central

    Fought, Rick L.

    2014-01-01

    Beginning in January 2012, a 1-year pilot pay-per-view (PPV) service was implemented. Twenty-four journal subscriptions were canceled to fund the service, and through the PPV service, the library was able to offer patrons access to over 700 previously unavailable biomedical journals. At the end of the pilot period, the total PPV cost for each journal accessed was compared to the subscription cost to determine if PPV was an effective use of library money. While remaining essentially budget neutral, the number of full-text articles accessed increased over 400%. PPV can be a cost-effective method for expanding access to journals. PMID:25031560

  6. Preliminary TES design optimization study for a simple periodic brick plant

    SciTech Connect

    Drake, J.B.; Olszewski, M.; Solomon, A.D.

    1989-03-01

    A general optimization method has been developed for maximizing the return on investment for a brick plant re-using waste heat with the capability of storing energy over periods when a kiln is not operating. The duct connections between devices and storage along with the operating schedule of flow rates in these ducts are the independent variables available for control. A combination of combinatorial search algorithms along with a dynamic programming model and the simplex method are layered to provide the optimization technique.

  7. Breaking inertia: increasing access to journals during a period of declining budgets: a case study.

    PubMed

    Fought, Rick L

    2014-07-01

    Beginning in January 2012, a 1-year pilot pay-per-view (PPV) service was implemented. Twenty-four journal subscriptions were canceled to fund the service, and through the PPV service, the library was able to offer patrons access to over 700 previously unavailable biomedical journals. At the end of the pilot period, the total PPV cost for each journal accessed was compared to the subscription cost to determine if PPV was an effective use of library money. While remaining essentially budget neutral, the number of full-text articles accessed increased over 400%. PPV can be a cost-effective method for expanding access to journals.

  8. Efficient biosynthesis of rare natural product scopolamine using E. coli cells expressing a S14P/K97A mutant of hyoscyamine 6β-hydroxylase AaH6H.

    PubMed

    Cao, Yue-De; He, Yu-Cai; Li, Hao; Kai, Guo-Yin; Xu, Jian-He; Yu, Hui-Lei

    2015-10-10

    Hyoscyamine 6β-hydroxylase (H6H, EC 1.14.11.11), an α-ketoglutarate dependent dioxygenase catalyzes the hydroxylation of (-)-hyoscyamine and the subsequent epoxidation of 6β-hydroxyhyoscyamine to form scopolamine, a valuable natural alkaloid. In this study, random mutagenesis and site-directed saturation mutagenesis were used to enhance the hydroxylation activity of H6H from Anisodus acutangulus (AaH6H). A double mutant, AaH6HM1 (S14P/K97A), showed a 3.4-fold improved hydroxylation activity compared with the wild-type enzyme, and the in vivo epoxidation activity was also improved by 2.3 times. After 34h cultivation of Escherichia coli cells harboring Aah6hm1 in a 5-L bioreactor with a working volume of 3L, scopolamine was produced via a single-enzyme-mediated two-step transformation from 500mgL(-1) (-)-hyoscyamine in 97% conversion, and 1.068g of the product were isolated, corresponding to a space-time yield of 251mgL(-1)d(-1). This study shows that the protein engineering of some key enzymes is a promising and effective way for improving the production of rare natural products such as scopolamine.

  9. Comparison of piperacillin/tazobactam and imipenem/cilastatin, both in combination with tobramycin, administered every 6 h for treatment of nosocomial pneumonia.

    PubMed

    Joshi, Manjari; Metzler, Michael; McCarthy, Mary; Olvey, Stephen; Kassira, Wedad; Cooper, Angel

    2006-09-01

    This randomized, double-blind, multicenter study compared the efficacy and safety of piperacillin/tazobactam (P/T) and imipenem/cilastatin (IMP), both in combination with an aminoglycoside, in hospitalized patients with acute nosocomial pneumonia (NP). Patients with acute NP, defined as pneumonia with symptoms > or = 48 h after admission or < or =7 days after hospital discharge, received infusions of 4 g/500 mg P/T or 500 mg/500 mg IMP every 6 h. Endpoints were clinical cure and microbiological response rates; pathogen eradication rates; length of hospital stay; hospital readmissions; and adverse events (AEs). Of 437 patients in the intent-to-treat population, 197 were efficacy evaluable. At test-of-cure, response rates were similar between groups. Within the efficacy evaluable population, 68% of P/T patients and 61% of IMP patients were clinically cured (P = 0.256). Microbiological responses for P/T and IMP patients were: eradication, 64% versus 59%; persistence, 29% versus 21%; relapse, 0% versus 5%; and superinfection, 7% versus 15%, respectively. Gram-positive isolates were eradicated in 83% of P/T patients and 75% of IMP patients; Gram-negative pathogens were eradicated in 72% of P/T patients and 77% of IMP patients. Treatment groups had similar number of mean hospital days, readmission rates, and frequency of AEs. This study showed that P/T administered four times per day was as safe and efficacious as IMP in treating hospitalized patients with NP.

  10. Evolution of Structure and Electrical Characteristics of Pt/WOx/6H-SiC Sensor Upon Exposure to H2 Gas at High Temperature

    NASA Astrophysics Data System (ADS)

    Zuev, V. V.; Demin, M. V.; Fominski, V. Yu.; Romanov, R. I.

    The bilayer film Pt/WOx was deposited by pulsed laser ablation on a silicon carbide monocrystal plate (6H-SiC) to form an H2 sensor for high temperature application. The study demonstrates high sensitivity of the Pt/WOx/SiC structure to a low H2 concentration. For 0.2 H2% in air at 350 °C, the shift of voltage on the reverse branch of the current-voltage characteristic reached 6.5 V at a current of 0.4 μA. After the high temperature interaction with H2, the sample can confine hydrogen atoms in the WOx layer at room temperature for a long time. The study explores the influence of operation conditions as well as the H2 action on the structure and electrical characteristics of the layers in the system. Phase transformation of the crystalline structure of the WOx film due to hydrogen penetration was detected and this process initiated pronounced electrical properties changes.

  11. Low Temperature Ohmic Contact Formation of Ni2Si on N-type 4H-SiC and 6H-SiC

    NASA Technical Reports Server (NTRS)

    Elsamadicy, A. M.; Ila, D.; Zimmerman, R.; Muntele, C.; Evelyn, L.; Muntele, I.; Poker, D. B.; Hensley, D.; Hirvonen, J. K.; Demaree, J. D.; Larkin, David (Technical Monitor)

    2001-01-01

    Nickel Silicide (Ni2Si) is investigated as possible ohmic contact to heavily nitrogen-doped N-type 4H-SiC and 6H-SiC. Nickel Silicide was deposited via electron gun with various thicknesses on both Si and C faces of the SiC substrates. The Ni2Si contacts were formed at room temperature as well as at elevated temperatures (400 to 1000 K). Contact resistivities and I-V characteristics were measured at temperatures between 100 and 700 C. To investigate the electric properties, I-V characteristics were studied and the Transmission Line Method (TLM) was used to determine the specific contact resistance for the samples at each annealing temperature. Both Rutherford Backscattering Spectroscopy (RBS) and Auger Electron Spectroscopy (AES) were used for depth profiling of the Ni2Si, Si, and C. X-ray Photoemission Spectroscopy (XPS) was used to study the chemical structure of the Ni2Si/SiC interface.

  12. Synthesis, structural characterization and dielectric properties of (C6H9N2)2(Hg0.75Cd0.25)Cl4 compound.

    PubMed

    Elwej, R; Hamdi, M; Hannachi, N; Hlel, F

    2014-01-01

    The present paper undertakes the study of a title compound whose structure is (C6H9N2)2(Hg0.75Cd0.25)Cl4. The centrosymmetric compound crystallizes in the triclinic space group P-1, with a=7.580(7) Å; b=8.572(8) Å; c=15.433(13) Å; α=84.49(5)°; β=89.13(5)°; γ=68.53(5)° and Z=2. The crystal structure was solved and refined to R (int)=0.0212 using 7932 independent reflections. The atomic arrangement shows an alternation of organic and inorganic layers. Between layers, the cohesion is performed via N-H⋯Cl hydrogen bonding, yet in the organic sheets, cations are further connected to classical π-π stacking. The Infrared and Raman spectra of this compound reported from 400 to 4000 cm(-1) confirmed the presence of the principal bands assigned to the internal modes of organic cation. Solid-state (13)C and (111)Cd CP-MAS-NMR spectra are reported. The dielectric study of this compound has been measured, in order to determine the σ(d.c) conductivity which is thermally activated with activation energy about 1.5 eV.

  13. Photometric study and absolute parameters of the short-period eclipsing binary HH Bootis

    NASA Astrophysics Data System (ADS)

    Gürol, B.; Bradstreet, D. H.; Demircan, Y.; Gürsoytrak, S. H.

    2015-11-01

    We present the results of our investigation on the geometrical and physical parameters of the W UMa type binary system HH Bootis from new CCD (BVRI) light curves and published radial velocity data. The photometric data were obtained in 2011 and 2012 at Ankara University Observatory (AUO). Light and radial velocity observations were analyzed simultaneously using the Wilson-Devinney (2013 revision) code to obtain absolute and geometrical parameters. The system was determined to be a W-type W UMa system of a type different from that suggested by Dal and Sipahi (2013). An interesting cyclic period variation in the time intervals between primary and secondary eclipses ("half-period variation") was discovered and analyzed and its possible cause is discussed. Combining our photometric solution with the spectroscopic data we derived masses and radii of the eclipsing system to be M1 = 0.627M⊙ , M2 = 1.068M⊙ , R1 = 0.782R⊙ and R2 = 0.997R⊙ . New light elements were derived and finally the evolutionary status of the system is discussed.

  14. The First Photometric Study of the Short-period Shallow Contact System LO Comae

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Han, Q. W.; Liu, J. Z.

    2016-12-01

    In this paper, the first complete photometric light curves in the B, V, and R passbands for an eclipsing binary LO Com are presented, and the photometric solution for the LO Com is derived by analyzing these light curves by using the Wilson and Devinney code. From the photometric solution, it is found that the LO Com is a W-type W UMa binary with a mass ratio of q={m}2/{m}1=2.478 and a contact degree of f=(3.2+/- 0.25) % . By combining the two new minimum times with those published earlier in the literature, we have found that the (O - C) curve shows a downward parabolic variation corresponding to a long-term decrease in the orbital period with a rate of {{d}}P/{{d}}t=-1.18× {10}-7 days yr-1. This long-term decrease in its orbital period may be caused by mass transfer from the more massive component to the less massive one.

  15. A study of the equatorial signatures of long period transient events (600 - 7200 s)

    NASA Astrophysics Data System (ADS)

    Santos, J.; Dutra, S.; Trivedi, N.; Vieira, L.; Echer, E.; Schuch, N.

    Transient variations in the H magnetic field component of magnetograms at high latitude are a common feature. They are associated with energy transference from solar wind to the magnetosphere. Abrupt changes in the solar wind generate Alfvén and fast mode waves through the magnetosphere. The Alfvén wave doesn't propagate in the direction perpendicular to the geomagnetic field, so equatorial signatures are probably caused by fast mode waves. On the other hand, complicated signatures observed at high latitudes represent a composition of Alfvén and fast mode waves. A second suggested propagation mechanism to low latitudes is the Earth-ionosphere wave-guide. In this work, geomagnetic data from the Brazilian magnetic stations at Belém (BLM), Eusébio (EUS), Ji-Paraná (JIP), São luis (SLZ) and São Martinho da Serra (SMS), all located near the geomagnetic equator, are used to look for equatorial signatures of transient events with periods of 600 - 7200s. This period range includes two special types of transient variations named Traveling convection vortices (TCV) and DP2 fluctuations. We try to identify their morphological characteristics and compare with the high latitude phenomena's characteristics. Satellite data (WIND, ACE and GOES) are used to see magnetosphere signatures and solar wind and interplanetary magnetic field (IMF) conditions during the events. The main objective is try to find the contribution of each propagation mechanism of these transient events arriving at the equatorial latitudes.

  16. Coding Properties of Three Intrinsically Distinct Retinal Ganglion Cells under Periodic Stimuli: A Computational Study

    PubMed Central

    Wang, Lei; Qiu, Yi-Hong; Zeng, Yanjun

    2016-01-01

    As the sole output neurons in the retina, ganglion cells play significant roles in transforming visual information into spike trains, and then transmitting them to the higher visual centers. However, coding strategies that retinal ganglion cells (RGCs) adopt to accomplish these processes are not completely clear yet. To clarify these issues, we investigate the coding properties of three types of RGCs (repetitive spiking, tonic firing, and phasic firing) by two different measures (spike-rate and spike-latency). Model results show that for periodic stimuli, repetitive spiking RGC and tonic RGC exhibit similar spike-rate patterns. Their spike- rates decrease gradually with increased stimulus frequency, moreover, variation of stimulus amplitude would change the two RGCs' spike-rate patterns. For phasic RGC, it activates strongly at medium levels of frequency when the stimulus amplitude is low. While if high stimulus amplitude is applied, phasic RGC switches to respond strongly at low frequencies. These results suggest that stimulus amplitude is a prominent factor in regulating RGCs in encoding periodic signals. Similar conclusions can be drawn when analyzes spike-latency patterns of the three RGCs. More importantly, the above phenomena can be accurately reproduced by Hodgkin's three classes of neurons, indicating that RGCs can perform the typical three classes of firing dynamics, depending on the distinctions of ion channel densities. Consequently, model results from the three RGCs may be not specific, but can also applicable to neurons in other brain regions which exhibit part(s) or all of the Hodgkin's three excitabilities. PMID:27721751

  17. Irregular Periods

    MedlinePlus

    ... number of days after the last one. The Menstrual Cycle Most girls get their first period between the ... to skip periods or to have an irregular menstrual cycle. Illness, rapid weight change, or stress can also ...

  18. Study of periodic surface profile on improving the window capacity at single and repetitive pulses

    SciTech Connect

    Liu, Y. S.; Zhang, X. W.; Zhang, Z. Q.; Shao, H.; Wang, Y.; Liu, W. Y.; Ke, C. F.; Chen, C. H.; Liang, Y. Q.; Wu, X. L.; Guo, L. T.; Chang, C.

    2015-09-15

    The surface breakdown of dielectric windows seriously limits the transmission of high power microwaves (HPM), and has blocked the development of microwave technology in recent decades. In this paper, X-band HPM experiments of window breakdown at the vacuum/dielectric interface and the atmosphere/dielectric interface at single and repetitive pulses were conducted. The cross-linked polystyrene (CLPS) dielectric window with a periodic surface profile can significantly improve the breakdown threshold at single and repetitive pulses. Furthermore, the flat surface layer of CLPS was discovered to be carbonized to a depth of several millimeters and filled with electrical trees at repetitive pulses. Theoretical models were built to understand the underlying physics behind the phenomena in experiments. With the analysis of the electron resonance process breaking the molecular bond and the temperature rise caused by the traversing current in the dielectric material, a microscopic explanation for the carbonization of the dielectric window was introduced.

  19. Transition metal complexes of the pyridylphosphine ligand o-C6H4(CH2PPy2)2.

    PubMed

    Vaughan, Teresa F; Spencer, John L

    2016-11-14

    The synthesis and coordination behaviour of the pyridylphosphine ligand o-C6H4(CH2PPy2)2 (Py = 2-pyridyl) are reported. The phosphine selenide was synthesised and the (1)JPSe value of 738 Hz indicates the phosphorus atoms have a similar basicity to PPh3. The ligand reacts with platinum(ii) and palladium(ii) complexes to give simple diphosphine complexes of the type [MX2(PP)] (M = Pt, X = Cl, I, Me, Et; M = Pd, X = Cl, Me). When the ligand is reacted with chloromethyl(hexa-1,5-diene)platinum the [PtClMe(PP)] complex results, from which a series of unsymmetrical platinum complexes of the type [PtMeL(PP)](+) (L = PPh3, PTA, SEt2 and pyridine) can be made. This enabled the comparison of the cis and trans influences of a range of ligands. The following cis influence series was compiled based on (31)P NMR data of these complexes: Py ≈ Cl > SEt2 > PTA > PPh3. Reaction of [PtClMe(PP)] with NaCH(SO2CF3)2 and carbon monoxide slowly formed an acyl complex, where the CO had inserted in the Pt-Me bond. Attempts to achieve P,P,N chelation, through abstracting the chloride ligand in [PtClMe(PP)], were unsuccessful. When the ligand reacted with platinum(0), palladium(0) and silver(i) complexes the bis-chelated complexes [M(PP)2] (M = Pt, Pd) and [Ag(PP)2](+) were formed respectively. Reaction of the ligand with [Ir(COD)(μ-Cl)]2 formed [IrCl(PP)(COD)]. When the chloride ligand was abstracted, the pyridyl nitrogens were able to interact with the iridium centre facilitating the isomerisation of the 1,2,5,6-η(4)-COD ligand to a 1-κ-4,5,6-η(3)-C8H12 ligand. The X-ray crystal structure of [Ir(1-κ-4,5,6-η(3)-C8H12)(PPN)]BPh4 confirmed the P,P,N chelation mode of the ligand. In solution, this complex displayed hemilabile behaviour, with the pyridyl nitrogens exchanging at a rate faster than the NMR time scale at room temperature.

  20. Experimental study and theoretical modeling of the long period variations of Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Alania, Michael; Siluszyk, Marek; Wawrzynczak-Szaban, Anna

    2012-07-01

    We analyze experimental data of neutron monitors and solar wind parameters during #21 solar cycle (1976-1987). In galactic cosmic ray (GCR) intensity is well established a step like changes in both ascending and descending periods of solar activity. We compose two-dimensional (2-D) time dependent model of GCR modulation based on Parker's transport equation to explain a general 11-year wave of the GCR intensity with the step-like changes, and each step-like changes individually, i.e. time scale of investigations is carried out by means of daily and monthly data. An innovation in proposed model is that besides the well known fundamental processes responsible for modulation of the GCR intensity, we implement in the model the parameters characterizing temporal changes of the exponent n of the Power Spectral Density (PSD) of the Interplanetary Magnetic Field (IMF) turbulence, module B of the IMF, tilt angle δ of the Heliospheric Neutral Sheet, and changes of drift effect of the GCR particles upon solar activity assuming that drift effect of the GCR particles is maximal in the minimum epoch, when drift dominates, and is neglected in the maximum epoch, when diffusion dominates. We show that an acceptable compatibility is kept for the investigated period of 1976-1987 (solar cycle #21), when the expected temporal changes of the GCR particles density (11-year wave) is shifted for 18 months with respect to the temporal changes of the smoothed experimental data of the GCR intensity. We consider, that a delay time ˜18 months can be considered as an effective delay time caused by the combined influence of all parameters implemented in the 2-D model.

  1. The study of atmospheric CO pollution over the center of Moscow in autumn period

    SciTech Connect

    Fokeeva, E.V.; Pekour, M.S.

    1996-12-31

    The results of CO near-ground concentration measurements are presented which were taken by virtue of electrochemical method at the center of Moscow during one autumn month in 1993. Simultaneous measurements were performed of the total column content of CO over Moscow making use of sun radiation absorption detection in the infrared (in the wavelength range of 4.6 mcm). To determine an urban increment of CO content over regional background the data of analogous measurements were used which were collected in the rural suburb 45 km west from Moscow center One-hour averaged near-ground CO concentration were in the limits 0.4 to 5.8 mg/m{sup 3}, and an average total column CO content vary from 0.09 to 0.167 atm*cm. The measurements were accompanied by acoustic sounding of the atmosphere boundary layer with the use of three component Doppler SODAR. The peculiarities of average and concrete diurnal variation of near-ground CO concentrations can well be interpreted by virtue of SODAR data indicating the type of stratification, the mixing height and the wind velocity during a whole day. Comparison and analysis are performed of the average diurnal variations of near-ground CO concentration in autumn and summer periods in account to the occurrence frequency of surface inversion within selected periods. Almost complete coincidence has been found of the shape of CO concentration diurnal variations with those of NO and soot. An estimate of specific CO source power in the city is performed in account to the data on the mixing height and wind velocity mean within a layer of 250 m.

  2. Vibrational state-selective autodetachment photoelectron spectroscopy from dipole-bound states of cold 2-hydroxyphenoxide: o − HO(C{sub 6}H{sub 4})O{sup −}

    SciTech Connect

    Huang, Dao-Ling; Wang, Lai-Sheng; Liu, Hong-Tao; Ning, Chuan-Gang

    2015-03-28

    We report a photodetachment and high-resolution photoelectron imaging study of cold 2-hydroxyphenoxide anion, o − HO(C{sub 6}H{sub 4})O{sup −}, cooled in a cryogenic ion trap. Photodetachment spectroscopy revealed a dipole-bound state (DBS) of the anion, 25 ± 5 cm{sup −1}, below the detachment threshold of 18784 ± 5 cm{sup −1} (2.3289 ± 0.0006 eV ), i.e., the electron affinity of the 2-hydroxyphenoxy radical o − HO(C{sub 6}H{sub 4})O{sup ⋅}. Twenty-two vibrational levels of the DBS are observed as resonances in the photodetachment spectrum. By tuning the detachment laser to these DBS vibrational levels, we obtain 22 high-resolution resonant photoelectron spectra, which are highly non-Franck-Condon due to mode-selective autodetachment and the Δv = − 1 propensity rule. Numerous Franck-Condon inactive vibrational modes are observed in the resonant photoelectron spectra, significantly expanding the vibrational information that is available in traditional high-resolution photoelectron spectroscopy. A total of 15 fundamental vibrational frequencies are obtained for the o − HO(C{sub 6}H{sub 4})O{sup ⋅}  radical from both the photodetachment spectrum and the resonant photoelectron spectra, including six symmetry-forbidden out-of-plane modes as a result of resonant enhancement.

  3. Quasi-white light emission involving Förster resonance energy transfer in a new organic inorganic tin chloride based material (AMPS)[SnCl6]H2O

    NASA Astrophysics Data System (ADS)

    Dammak, Thameur; Abid, Younes

    2017-04-01

    This work deals with optical properties of a new organic inorganic material: 3, 3‧-Diaminodiphenyl-sulfone tin chloride with the formula (C12H14N2O2S)[SnCl6]H2O abbreviated as (AMPS)[SnCl6]H2O. Single crystals of (AMPS)[SnCl6]H2O were elaborated by the solvent evaporation method and investigated by X-ray diffraction, optical absorption (OA), photoluminescence (PL) and photoluminescence excitation (PLE). The crystal structure is composed of discrete [SnCl6] anions surrounded by organic (AMPS) cations and H2O molecules. For optical investigations, thin films have been prepared by spin-coating method from the ethanol solution of the material. Photoluminescence measurements show a quasi-white light and intense emission which can be observed even with naked eye at room temperature. This emission is believed to be due to excitonic recombination involving a Förster resonance energy transfer mechanism in which (AMPS) molecule acts as a donor and [SnCl6] molecule acts as an acceptor. Moreover, the temperature dependence study of the photoluminescence in term of Varshni and Arrhenius models reveals the free character of the inorganic exciton and shows that the organic exciton is rather localized.

  4. Dynamics of O{sup 6+} + H electron capture in Debye plasmas and properties of resulting O{sup 5+}(nl) emission spectra

    SciTech Connect

    Zhao, Y. Q.; Xue, P.; Liu, L.; Wang, J. G.; Janev, R. K.

    2010-08-15

    The electron capture in O{sup 6+}-H collisions is studied by the two-center atomic orbital close-coupling (TC-AOCC) method when the interactions of charged particles are screened and have a Yukawa form. Atomic orbitals and eigenenergies of n {<=} 6 states on O{sup 5+} and n {<=} 2 states on H are calculated as a function of the interaction screening parameter and used in the AOCC dynamics scheme to calculate the electron capture cross sections in the energy range 1-200 keV/u. It is shown that the degree of interaction screening reduces the electron binding energies, the number of open electron capture channels, and the strength of exchange couplings, thus affecting the entire collision dynamics and the magnitude and energy behavior of electron capture cross sections. The state-selective electron capture cross sections in this collision system, as well as the intensities of a number of charge exchange spectral lines, for a number of representative interaction screening strengths are presented and discussed.

  5. Effect of TiO2 on Sintering and Grain Growth Kinetics of MgO from MgCl2·6H2O

    NASA Astrophysics Data System (ADS)

    Huang, Qiong-Zhu; Lu, Gui-Min; Sun, Ze; Song, Xing-Fu; Yu, Jian-Guo

    2013-04-01

    The effect of TiO2 on the grain growth kinetics of MgO prepared from MgCl2·6H2O was studied by the tradition phenomenological rate equation. The results showed that the addition of TiO2 decreased the activation energy of MgO grain growth, accelerated the growth rate of MgO grain, and markedly promoted the sintering of MgO. Without TiO2 addition, the MgO grain growth exponent n was 3, the grain growth activation energy Q was 556.9 kJ·mol-1, and the process was considered as volume diffusion controlled. With 0.2 wt pct TiO2 addition, the MgO grain growth exponent n was 2, the grain growth activation energy Q was 272.8 kJ·mol-1, and the process was considered as interface diffusion controlled. The apparent and closed porosities of MgO-0.2 wt pct TiO2 sample were decreased significantly, and the bulk density increased to 3.49 g·cm-3 (relative density is 97.5 pct). The main mechanism of TiO2 promoting the sintering of MgO was that TiO2 solubilized in MgO to form unequivalence substitutional solid solutions and cation vacancies that were favorable to cation diffusion.

  6. cAMP dependent and independent regulation of thyroglobulin synthesis by two clones of the OVNIS 6H thyroid cell line.

    PubMed

    Aouani, A; Hovsépian, S; Fayet, G

    1987-07-01

    The hormonal regulation of thyroglobulin synthesis has been studied using two independent clones of the OVNIS 6H cell line. Insulin, hydrocortisone and TSH were able to stimulate thyroglobulin synthesis, whereas transferrin, somatostatin and glycyl-histidyl-lysine were without effect. Insulin stimulated thyroglobulin synthesis without affecting cAMP production. Hydrocortisone, when combined with insulin was a stimulator too; this stimulation was not accompanied by an increase in cAMP. TSH alone was unable to stimulate either cAMP or thyroglobulin synthesis. The stimulatory effect of TSH on thyroglobulin synthesis took place only when combined with insulin or insulin plus hydrocortisone, and was mediated by cAMP. Consequently, insulin and hydrocortisone stimulated thyroglobulin synthesis by cAMP-independent mechanisms, whereas TSH acted via the cAMP system. Forskolin mimicked TSH effects on cAMP and thyroglobulin synthesis. Calf serum inhibited cAMP and thyroglobulin production. Optimal cAMP and thyroglobulin synthesis as well as TSH responsiveness were obtained in serum-free medium supplemented with 5 micrograms/ml insulin, 100 nM hydrocortisone and 1 mU/ml TSH.

  7. Abnormal difference between the mobilities of left- and right-twisted conformations of C6H12N2 roto-symmetrical molecules at very low temperatures.

    PubMed

    Gabuda, S P; Kozlova, S G

    2015-06-21

    We report an abnormal difference of low-temperature mobility of left-twisted and right-twisted conformations of roto symmetric molecules C6H12N2 (dabco) located in the same positions in crystal Zn2(C8H4O4)2⋅C6H12N2. The difference between (1)H NMR (Nuclear Magnetic Resonance) spin-relaxation data for left-twisted and right-twisted molecules reaches ∼3 × 10(3) times at 8 K and tends to grow at lower temperatures. We argue that taking into account four-component relativistic Dirac wave functions in the vicinity of the nodal plane of dabco molecules and vacuum fluctuations due to virtual particle-antiparticle pairs can explain the changes which C6H12N2 conformations undergo at low temperatures.

  8. Design of laser pulses for selective vibrational excitation of the N6-H bond of adenine and adenine-thymine base pair using optimal control theory.

    PubMed

    Sharma, Sitansh; Sharma, Purshotam; Singh, Harjinder; Balint-Kurti, Gabriel G

    2009-06-01

    Time dependent quantum dynamics and optimal control theory are used for selective vibrational excitation of the N6-H (amino N-H) bond in free adenine and in the adenine-thymine (A-T) base pair. For the N6-H bond in free adenine we have used a one dimensional model while for the hydrogen bond, N6-H(A)...O4(T), present in the A-T base pair, a two mathematical dimensional model is employed. The conjugate gradient method is used for the optimization of the field dependent cost functional. Optimal laser fields are obtained for selective population transfer in both the model systems, which give virtually 100% excitation probability to preselected vibrational levels. The effect of the optimized laser field on the other hydrogen bond, N1(A)...H-N3(T), present in A-T base pair is also investigated.

  9. Tungsten phosphanylarylthiolato complexes [W{PhP(2-SC6H4)2-kappa3S,S',P} 2] and [W{P(2-SC6H4)3-kappa4S,S',S",P}2]: synthesis, structures and redox chemistry.

    PubMed

    Hildebrand, Alexandra; Lönnecke, Peter; Silaghi-Dumitrescu, Luminita; Hey-Hawkins, Evamarie

    2008-09-14

    PhP(2-SHC6H4)2 (PS2H2) reacts with WCl6 with reduction of tungsten to give the air-sensitive tungsten(IV) complex [W{PhP(2-SC6H4)2-kappa(3)S,S',P}2] (1). 1 is oxidised in air to [WO{PhPO(2-SC6H4)2-kappa(3)S,S',O}{PhP(2-SC6H4)2-kappa(3)S,S',P}] (2). The attempted synthesis of 2 by reaction of 1 with iodosobenzene as oxidising agent was unsuccessful. [W{P(2-SC6H4)3-kappa(4)S,S',S",P}2] (3) was formed in the reaction of P(2-SHC6H4)3 (PS3H3) with WCl6. The W(VI) complex 3 contains two PS3(3-) ligands, each coordinated in a tetradentate fashion resulting in a tungsten coordination number of eight. The reaction of 3 with AgBF4 yields the dinuclear tungsten complex [W2{P(2-SC6H4)3-kappa(4)S,S',S",P}3]BF4 (4). Complexes 1-4 were characterised by spectral methods and X-ray structure determination.

  10. Thirteen Week Oral Toxicity Study of WR238605 with a Thirteen Week Recovery Period in Dogs. Volume 3

    DTIC Science & Technology

    1993-06-11

    INDIVIDUAL ANIMAL REPORT BY GROUP TEST: Mean Corpuscular Volume STUDY 10: 097 STUDY NO: 097 ABBR: HCV ANIMAL 10 ~eek ·3 ~eek ·1 GROUP: 7557 7541...097 ABBR: HCV ANIMAL 10 ~eek ·3 INDIVIDUAL ANIMAL REPORT BY GROUP TEST: Mean Corpuscular Volume IJeek ·1 IJeek 2 IJeek 4 IJeelc 8 IJeek 13...animals sacrificed after the recovery period. It was usually focal and subcapsular. It consisted of interstitial fibrosis , mononuclear cell

  11. Timing Studies of X Persei and the Discovery of Its Transient Quasi-periodic Oscillation Feature

    NASA Technical Reports Server (NTRS)

    Acuner, Z.; Inam,S. C.; Sahiner, S.; Serim, M. M.; Baykal, A.; Swank, J.

    2014-01-01

    We present a timing analysis of X Persei (X Per) using observations made between 1998 and 2010 with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE) and with the INTEGRAL Soft Gamma-Ray Imager (ISGRI). All pulse arrival times obtained from the RXTE-PCA observations are phase-connected and a timing solution is obtained using these arrival times. We update the long-term pulse frequency history of the source by measuring its pulse frequencies using RXTE-PCA and ISGRI data. From the RXTEPCA data, the relation between the frequency derivative and X-ray flux suggests accretion via the companion's stellar wind. However, the detection of a transient quasi-periodic oscillation feature, peaking at approximately 0.2 Hz, suggests the existence of an accretion disc. We find that doublebreak models fit the average power spectra well, which suggests that the source has at least two different accretion flow components dominating the overall flow. From the power spectrum of frequency derivatives, we measure a power-law index of approximately - 1, which implies that, on short time-scales, disc accretion dominates over noise, while on time-scales longer than the viscous time-scales, the noise dominates. From pulse profiles, we find a correlation between the pulse fraction and the count rate of the source.

  12. A numerical study of periodic slug flow at zero gravity and normal gravity

    NASA Astrophysics Data System (ADS)

    Mack, K.; Bugg, J. D.; Gabriel, K. S.

    2005-12-01

    This paper reports numerical simulations of slug flow at zero and normal gravity. The particular experimental results chosen for validation were obtained at microgravity under conditions which resulted in evenly-spaced and evenly-sized Taylor bubbles facilitating a simulation with periodic boundary conditions. The numerical technique was a free-surface method which explicitly tracked the motion of the gas-liquid interface using a volume-of-fluid specification and a finite volume discretisation of the solution domain. The large scale features of the bubble such as the classic bullet-shaped nose were well predicted by the model. Unsteady features of the bubble shape such as waves in the film and fluctuations of the bottom surface were also predicted but are harder to compare quantitatively to the experiments. The velocity field predictions reveal several interesting features of the flow. When viewed by an observer moving with the bubbles, the liquid slug is dominated by a large recirculating region with the flow travelling from the leading to the trailing bubble along the tube centreline. In this frame of reference, the near-wall region features a jet of fluid issuing from the film of the leading bubble which entrains fluid in the slug. As the film of the trailing bubble begins to form, the entrained fluid must be ejected since the flowrate in the film of each bubble must be the same. It appears to be this process that drives the main recirculation.

  13. ''Inelastic Neutron Scattering and Periodic Density Functional Studies of Hydrogen Bonded Structures''

    SciTech Connect

    Bruce S. Hudson

    2004-10-27

    This project is directed at a fundamental understanding of hydrogen bonding, the primary reversible interaction leading to defined geometries, networks and supramolecular aggregates formed by organic molecules. Hydrogen bonding is still not sufficiently well understood that the geometry of such supramolecular aggregates can be predicted. In the approach taken existing quantum chemical methods capable of treating periodic solids have been applied to hydrogen bonded systems of known structure. The equilibrium geometry for the given space group and packing arrangement were computed and compared to that observed. The second derivatives and normal modes of vibration will then be computed and from this inelastic neutron scattering (INS) spectra were computed using the normal mode eigenvectors to compute spectral intensities. Appropriate inclusion of spectrometer line width and shape was made in the simulation and overtones, combinations and phonon wings were be included. These computed spectra were then compared with experimental results obtained for low-temperature polycrystalline samples at INS spectrometers at several facilities. This procedure validates the computational methodology for describing these systems including both static and dynamic aspects of the material. The resulting description can be used to evaluate the relative free energies of two or more proposed structures and so ultimately to be able to predict which structure will be most stable for a given building block.

  14. The study of structural color filter based on periodic nanohole arrays for bio-detection

    NASA Astrophysics Data System (ADS)

    Kim, Seunguk; Shin, Jeonghee; Yoo, Seungjun; Kim, Samhwan; Jeon, Byoungok; Moon, Cheil; Jang, Jae-Eun

    2015-07-01

    A nanostructure which induces localized surface plasmon resonance (LSPR) can be utilized in visible light and near infrared (NIR) regions and it shows promising features as a bio-detector because LSPR state is changed easily by different bio-related materials. Owing to transparent property of many biomolecules as well as diluted states in base solutions, it is hard to distinguish each other by eye or microscope analysis. However, difference in molecular structure and composition makes difference in optical characteristics such as a refractive index or a dielectric constant. Therefore, our LSPR-based nanohole array structure which has high sensitivity to detect small changes in optical characteristics can be a great candidate for a bio detector. Here, we fabricated structural color filters (SCFs) to detect wavelength shifts for several biomolecules and optimized the nanohole array structures for high sensitivity. Periodic nanohole arrays were designed to present resonance peaks in visible light region for optical analysis and fabricated in Au or Al thin film layer. The spectral shifts were detected caused by biomolecules.

  15. Evanescent-wave amplification studied using a bilayer periodic circuit structure and its effective medium model

    NASA Astrophysics Data System (ADS)

    Liu, Ruopeng; Zhao, Bo; Lin, Xian Qi; Cheng, Qiang; Cui, Tie Jun

    2007-03-01

    In this paper, we present both theoretical analysis and experimental verification of evanescent-wave amplification by using a bilayer periodic circuit structure and its effective medium model. We propose a series-shunt capacitor (C-C) structure to simulate a magnetic plasma, whose permittivity is positive and permeability is negative, and a series-shunt inductor (L-L) structure to simulate an electric plasma, whose permittivity is negative and permeability is positive, in which the structure cells are not required to be electrically small. In addition, we derive and define an effective permittivity and permeability for the C-C and L-L structures in closed forms, which are completely different from the published ones. When the two structures are cascaded together to form a bilayer structure, we show that evanescent waves which exist in two single layers independently can be amplified exponentially if a certain resonant condition is satisfied. Such a resonant condition is equivalent to the antimatching condition for the permittivity and permeability of the effectively electric and magnetic plasmas. To show the accuracy of this equivalent medium model, we compare both circuit-simulation results for the C-C and L-L structures and theoretical-prediction results for the effective magnetic and electric plasmas, which have excellent agreement. Finally, we design an experiment using lumped capacitors and inductors mounted on a printed circuit board to verify the amplification of evanescent waves sufficiently. The measurement results have good agreement with the simulation results.

  16. An infrared pump-probe measurement of the Sm3+6H7/2 lifetime in LiYF4

    NASA Astrophysics Data System (ADS)

    Horvath, Sebastian P.; Wells, Jon-Paul R.; van der Meer, Alexander F. G.; Reid, Michael F.

    2017-04-01

    We report a pump-probe measurement of the lifetime of the 6H7/2 multiplet of Sm3+:LiYF4. A lifetime of 3.1 ± 0.3 ps was inferred for the Y2 level of the 6H7/2 multiplet. This lifetime is two orders of magnitude faster than for a similar energy gap in Nd3+:LiYF4, and does not follow the prediction of a simple exponential energy-gap law for non-radiative relaxation in this material.

  17. Effect of ammonia excess on the crystal habit of NiNH4PO4.6H2O (Ni-struvite)

    NASA Astrophysics Data System (ADS)

    Abbona, F.; Angela-Franchini, M.; Bono, C. Croni; Madsen, H. E. Lundager

    1994-10-01

    The change of crystal habit and the repeated nucleations of NiNH4PO4.6H2O (Ni-struvite) occurring as a consequence of NH3 addition to a solution of nickel and phosphate ions (the concentration of Ni = the concentration of PO4 = 5mM) are described and interpreted. The amorphous compound Ni(OH)2, which always accompanies the crystallization of Ni-struvite, and the Ni-NH3 complexes play a determining role in the process. The isomorphous MgNH4PO.6H2O (struvite), grown under the same conditions, shows a totally different crystal habit.

  18. Measurement of N-Type 6H SiC Minority-Carrier Diffusion Lengths by Electron Bombardment of Schottky Barriers

    NASA Technical Reports Server (NTRS)

    Hubbard, S. M.; Tabib-Azar, M.; Balley, S.; Rybickid, G.; Neudeck, P.; Raffaelle, R.

    2004-01-01

    Minority-Carrier diffusion lengths of n-type 6H-SiC were measured using the electron-beam induced current (EBIC) technique. Experimental values of primary beam current, EBIC, and beam voltage were obtained for a variety of SIC samples. This data was used to calculate experimental diode efficiency vs. beam voltage curves. These curves were fit to theoretically calculated efficiency curves, and the diffusion length and metal layer thickness were extracted. The hole diffusion length in n-6H SiC ranged from 0.93 +/- 0.15 microns.

  19. The reactions of para-halo diaryl diselenides with halogens. A structural investigation of the CT compound (p-FC6H4)2Se2I2, and the first reported “RSeI3” compound, (p-ClC6H4)SeI·I2, which contains a covalent Se-I bond.

    PubMed

    Barnes, Nicholas A; Godfrey, Stephen M; Hughes, Jill; Khan, Rana Z; Mushtaq, Imrana; Ollerenshaw, Ruth T A; Pritchard, Robin G; Sarwar, Shamsa

    2013-02-28

    The reactions of the diaryl-diselenides (p-FC(6)H(4))(2)Se(2) and (p-ClC(6)H(4))(2)Se(2) with diiodine have been investigated. Species of stoichiometry "RSeI" are formed when the ratio employed is 1:1. The solid-state structure of "(p-FC(6)H(4))SeI" has been determined, and shown to be a charge-transfer (CT) adduct, (p-FC(6)H(4))(2)Se(2)I(2), where the Se-Se bond is retained and the diiodine molecule interacts with only one of the selenium atoms. The Se-I bond in (p-FC(6)H(4))(2)Se(2)I(2) is 2.9835(12) Å, which is typical for a (10-I-2) Se-I-I CT system. When diiodine is reacted in a 3:1 ratio with (p-XC(6)H(4))(2)Se(2) (X = F, Cl) species of stoichiometry "RSeI(3)" are formed. The structure of "(p-ClC(6)H(4))SeI(3)" reveals that this is not a selenium(IV) compound, but is better represented as a selenium(II) CT adduct, (p-ClC(6)H(4))SeI·I(2). The Se-I bond to the diiodine molecule is typical in magnitude for a CT adduct, Se-I: 2.8672(5) Å, whereas the other Se-I bond is much shorter, Se-I: 2.5590(6) Å, and is a genuine example of a rarely observed covalent Se-I bond, which appears to be stabilised by a weak Se···I interaction from a neighbouring iodine atom. The reaction of (p-ClC(6)H(4))SeI with Ph(3)P results in the formation of a CT adduct, Ph(3)PSe(p-ClC(6)H(4))I, which has a T-shaped geometry at selenium (10-Se-3). By contrast, the reaction of (p-FC(6)H(4))SeI with Ph(3)P does not form an adduct, but results in the formation of Ph(3)PI(2) and (p-FC(6)H(4))(2)Se(2).

  20. Periodic limb movements during sleep and prevalent hypertension in the multi-ethnic study of atherosclerosis.

    PubMed

    Koo, Brian B; Sillau, Stefan; Dean, Dennis A; Lutsey, Pamela L; Redline, Susan

    2015-01-01

    Periodic limb movements during sleep (PLMS) are associated with immediate increases in blood pressure. Both PLMS and hypertension have different distributions across racial/ethnic groups. We sought to determine whether PLMS is associated with hypertension among various racial/ethnic groups. A total of 1740 men and women underwent measurement of blood pressure and polysomnography with quantification of PLMS. Hypertension was defined as systolic blood pressure (SBP) ≥140, diastolic BP ≥90, or taking antihypertensive medication. For those taking antihypertensives, an estimated pretreatment SBP value was derived based on observed SBP and medication type/dose. Measures of PLMS, PLMS index, and PLMS arousal index were the main explanatory variables. Hypertension and SBP were modeled with logistic and multivariable regression adjusted for age, sex, body mass index, cardiovascular risk factors, lifestyle/habitual factors, apnea-hypopnea index, and race/ethnicity. In the overall cohort, prevalent hypertension was modestly associated with PLMS index (10 U; odds ratio, 1.05; 95% confidence interval, 1.00-1.10) and PLMS arousal index (1 U; 1.05; 1.01-1.09) after adjusting for confounders. Association in the overall cohort was influenced by large effect sizes in blacks, in whom the odds of prevalent hypertension increased by 21% (1%-45%) for 10 U PLMS index increase and 20% (2%-42%) for 1-U PLMS arousal index increase. In blacks, every 1-U PLMS arousal index increase was associated with SBP 1.01 mm Hg higher (1.01; 0.04-1.98). Associations between PLMS and blood pressure outcomes were also suggested among Chinese-Americans but not in whites or Hispanics. In a multiethnic cohort of community-dwelling men and women, prevalent hypertension and SBP are associated with PLMS frequency in blacks.

  1. Experimental study of outdoor propagation of spherically speading periodic acoustic waves of finite amplitude

    NASA Technical Reports Server (NTRS)

    Theobald, M. A.

    1977-01-01

    The outdoor propagation of spherically spreading sound waves of finite amplitude was investigated. The main purpose of the experiments was to determine the extent to which the outdoor environment, mainly random inhomogeneity of the medium, affects finite amplitude propagation. Periodic sources with fundamental frequencies in the range 6 to 8 kHz and source levels SPLlm from 140 to 149 dB were used. The sources were an array of 7 to 10 horn drivers and a siren. The propagation path was vertical and parallel to an 85 m tower, whose elevator carried the traveling microphone. The general conclusions drawn from the experimental results were as follows. The inhomogeneities caused significant fluctuations in the instantaneous acoustic signal, but with sufficient time averaging of the measured harmonic levels, the results were comparable to results expected for propagation in a quiet medium. Propagation data for the fundamental of the siren approached within 1 dB of the weak shock saturation levels. Extra attenuation on the order of 8 dB was observed. The measurements generally confirmed the predictions of several theoretical models. The maximum propagation distance was 36 m. The narrowbeam arrays were much weaker sources. Nonlinear propagation distortion was produced, but the maximum value of extra attenuation measured was 1.5 dB. The maximum propagation distance was 76 m. The behavior of the asymetric waveforms received in one experiment qualitatively suggested that beam type diffraction effects were present. The role of diffraction of high intensity sound waves in radiation from a single horn was briefly investigated.

  2. Undergraduate Pilot Training Task Frequency Study. Final Report for Period October 1972-October 1974.

    ERIC Educational Resources Information Center

    Brown, James E.; Rust, Steven K.

    The objectives of the study were: (1) to determine the number of training task repetitions required for an Undergraduate Pilot Training (UPT) student to become proficient, and (2) to determine the total number of task repetitions that UPT students receive for each maneuver in T-37 and T-38 training. The project was conducted in two parts. Study 1…

  3. Work Sampling Study of an Engineering Professor during a Regular Contract Period

    ERIC Educational Resources Information Center

    Brink, Jan; McDonald, Dale B.

    2015-01-01

    Work sampling is a technique that has been employed in industry and fields such as healthcare for some time. It is a powerful technique, and an alternative to conventional stop watch time studies, used by industrial engineers to focus upon random work sampling observations. This study applies work sampling to the duties performed by an individual…

  4. Using the Fourier-series approach to study interactions between moving wheels and a periodically supported rail

    NASA Astrophysics Data System (ADS)

    Sheng, X.; Li, M.; Jones, C. J. C.; Thompson, D. J.

    2007-06-01

    In this paper, the Fourier-series approach is employed to study wheel-rail interactions generated by a single, or multiple wheels moving at a constant speed along a railway track. This approach has been previously explored by other researchers and what is presented here is an improved version. In this approach, the track is represented by an infinitely long periodic structure with the period equal to the sleeper spacing and the vertical irregular profile (roughness) of the railhead is assumed to be periodic in the track direction with the period equal to the length of a number (integer), N, of sleeper bays. By assuming linear dynamics for the wheel/track system and for steady state, each wheel/rail force is a periodic function of time and can be expressed as a Fourier series. Fourier coefficients are then shown to be determined by solving, separately, N sets of linear algebraic equations. The coefficient matrix of each set of equations is independent of rail roughness and therefore this approach is particularly useful in modelling the generation and growth of rail roughness of short wavelengths. Excitation purely from the axle loads moving over the periodic track structure is realised by assuming a smooth railhead surface, and subsequently roughness equivalent to such an excitation is defined and evaluated. This equivalent roughness may, in addition to the actual rail roughness, be input into models in which the effect of moving axle loads has been excluded, so that the predictions from those models can be improved. Results are produced using the improved Fourier-series approach to investigate the effects of wheel speeds, roughness wavelengths and interactions between multiple wheels on wheel/rail contact forces.

  5. Thirteen Week Oral Toxicity Study of WR242511 with a Thirteen Week Recovery Period in Dogs. Volume 2 of 2

    DTIC Science & Technology

    1996-03-07

    HISTORICAL DATABASE REPORT HCV PLT PT RBC RETICS WBC DBA IF IF DOG BEAGLE Male CONTROL DATA MEAN 69.6 286 7.8 6.37 0.4 8.2...PERIOD IN DOGS EMI?? INDIVIDUAL ANIMAL HEMATOLOGY REPORT BY GROUP TEST: Mean Corpuscular Volume STUDY ID: UIC-18 - SEX: HALE STUDY NO: 193 ABBR: HCV ...Corpuscular Volume STUDY ID: UIC-18 STUDY NO: 193 ABBR: HCV - SEX: FEMALE UNITS: fL Animal ID WEEK -3 WEEK -1 WEEK 4

  6. Homo-polymerization of alpha-olefins and co-polymerization of higher alpha-olefins with ethylene in the presence of CpTiCl2(OC6H4X-p)/MAO catalysts (X = CH3, Cl).

    PubMed

    Skupinski, W; Nicinski, K; Jamanek, D; Wieczorek, Z

    2005-07-04

    Cyclopentadienyl-titanium complexes containing -OC6H4X ligands (X = Cl,CH3) activated with methylaluminoxane (MAO) were used in the homo-polymerization of ethylene, propylene, 1-butene, 1-pentene, 1-butene, and 1-hexene, and also in co-polymerization of ethylene with the alpha-olefins mentioned. The -X substituents exhibit different electron donor-acceptor properties, which is described by Hammett's factor (sigma). The chlorine atom is electron acceptor, while the methyl group is electron donor. These catalysts allow the preparation of polyethylene in a good yield. Propylene in the presence of the catalysts mentioned dimerizes and oligomerizes to trimers and tetramers at 25 degrees C under normal pressure. If the propylene pressure was increased to 7 atmospheres,CpTiCl2(OC6H4CH3)/MAO catalyst at 25 degrees gave mixtures with different contents of propylene dimers, trimers and tetramers. At 70 degrees C we obtained only propylene trimer. Using the catalysts with a -OC(6)H(4)Cl ligand we obtained atactic polymers with M(w) 182,000 g/mol (at 25 degrees C) and 100,000 g/mol (at 70 degrees C). The superior activity of the CpTiCl2(OC6H4Cl)/MAO catalyst used in polymerization of propylene prompted us to check its activity in polymerization of higher alpha-olefins (1-butene, 1-pentene, 1-hexene)and in co-polymerization of these olefins with ethylene. However, when homo-polymerization was carried out in the presence of this catalyst no polymers were obtained. Gas chromatography analysis revealed the presence of dimers. The activity of the CpTiCl2(OC6H4Cl)/MAO catalyst in the co-polymerization of ethylene with higher alpha-olefins is limited by the length of the co-monomer carbon chain. Hence, the highest catalyst activities were observed in co-polymerization of ethylene with propylene (here a lower pressure of the reagents and shorter reaction time were applied to obtain catalytic activity similar to that for other co-monomers). For other co-monomers the activity of the

  7. Complete dataset for 2-treatment, 2-sequence, 2-period efavirenz bioequivalence study conducted with nightly dosing.

    PubMed

    Ibarra, Manuel; Magallanes, Laura; Lorier, Marianela; Vázquez, Marta; Fagiolino, Pietro

    2016-06-01

    The efavirenz pharmacokinetic raw data presented in this article was obtained in an average bioequivalence study between a local brand and Stocrin (Merck Sharp & Dohme, purchased from Australia, batch H009175, expiration date November 2013). Dose was administered at night (9:00 p.m.) two hours after food intake. Fourteen healthy subjects, 8 women and 6 men, completed the study. For each subject, 15 data points until 96 h post-administration are included. Subject demographic characteristics and sequences of administration are provided along with individual pharmacokinetic profiles of efavirenz obtained for both formulations after a single oral dose of 600 mg. This data provides information in support of the research article "Sex-by-formulation interaction assessed through a bioequivalence study of efavirenz tablets" [1].

  8. Complete dataset for 2-treatment, 2-sequence, 2-period efavirenz bioequivalence study conducted with nightly dosing

    PubMed Central

    Ibarra, Manuel; Magallanes, Laura; Lorier, Marianela; Vázquez, Marta; Fagiolino, Pietro

    2016-01-01

    The efavirenz pharmacokinetic raw data presented in this article was obtained in an average bioequivalence study between a local brand and Stocrin (Merck Sharp & Dohme, purchased from Australia, batch H009175, expiration date November 2013). Dose was administered at night (9:00 p.m.) two hours after food intake. Fourteen healthy subjects, 8 women and 6 men, completed the study. For each subject, 15 data points until 96 h post-administration are included. Subject demographic characteristics and sequences of administration are provided along with individual pharmacokinetic profiles of efavirenz obtained for both formulations after a single oral dose of 600 mg. This data provides information in support of the research article “Sex-by-formulation interaction assessed through a bioequivalence study of efavirenz tablets” [1]. PMID:27054190

  9. A prospective study of atopic dermatitis managed without topical corticosteroids for a 6-month period

    PubMed Central

    Fukaya, Mototsugu; Sato, Kenji; Yamada, Takahiro; Sato, Mitsuko; Fujisawa, Shigeki; Minaguchi, Satoko; Kimata, Hajime; Dozono, Haruhiko

    2016-01-01

    Topical corticosteroids (TCS) are regarded as the mainstay treatment for atopic dermatitis (AD). As AD has a tendency to heal naturally, the long-term efficacy of TCS in AD management should be compared with the outcomes seen in patients with AD not using TCS. However, there are few long-term studies that consider patients with AD not using TCS. We designed a prospective multicenter cohort study to assess the clinical outcomes in patients with AD who did not use TCS for 6 months and then compared our results with an earlier study by Furue et al which considered AD patients using TCS over 6 months. Our patients’ clinical improvement was comparable with the patients described in Furue’s research. In light of this, it is reasonable for physicians to manage AD patients who decline TCS, as the expected long-term prognosis is similar whether they use TCS or not. PMID:27445501

  10. Single cell contractility studies based on compact moiré system over periodic gratings

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoyu; Surks, Howard; Zhang, Xin

    2010-05-01

    Abnormal vascular cell contractile performance is a hallmark of cardiovascular diseases. Conventional cell force measurement technique requires individually tracking the sensing units and complex computation efforts for further studying cell contractility. We developed instead a robust and simple compact optical moiré system that measures phase changes encoded in carrier moiré patterns generated from two layers of gratings. Cell mechanics study including cell contractile forces and stress and strain distributions during normal and abnormal cell contractions can thus be conveniently analyzed. The distinct signals from moiré patterns in longitudinal and transverse directions revealed abnormal cell mechanical contractility linked to cardiovascular disease.

  11. 13-week drinking water toxicity study of hydrogen peroxide with 6-week recovery period in catalase-deficient mice.

    PubMed

    Weiner, M L; Freeman, C; Trochimowicz, H; de Gerlache, J; Jacobi, S; Malinverno, G; Mayr, W; Regnier, J F

    2000-07-01

    A GLP OECD guideline study was conducted to evaluate the subchronic toxicity of hydrogen peroxide (HP) when administered continuously in the drinking water of catalase-deficient (C57BL/6N) mice and reversibility of toxic effects. Groups of mice (15/sex/group) received solutions of 0, 100, 300, 1000 or 3000 ppm HP in distilled water for 13 weeks; five/sex/group continued on untreated distilled water for an additional 6 weeks. Animals drinking 3000 ppm HP exhibited depressed water and food consumption and body weight. Females drinking 1000 ppm HP had reduced water consumption with intermittent effects on food consumption, but no body weight effects. HP administration did not produce any mortality, clinical signs, hematological effects or organ weight effects on brain, liver, kidneys, adrenals, testes, heart or spleen. Total protein and globulin were depressed among high dose males. Mild to minimal duodenal mucosal hyperplasia was noted in animals receiving 1000 and 3000 ppm HP and one male receiving 300 ppm for 13 weeks. There were no other histopathological findings. All effects noted during the treatment period, including the duodenal hyperplasia, were reversible during the 6-week recovery period. Females dosed with 300-3000 ppm HP during the treatment period showed increased water consumption during the recovery period. The no-observed-effect level (NOEL), based on duodenal mucosal hyperplasia, is 100 ppm in drinking water or 26 and 37 mg/kg/day HP, respectively, for males and females.

  12. Solid-like and liquid-like behaviour in small benzene clusters. A molecular dynamics simulation of (C 6H 6) 4

    NASA Astrophysics Data System (ADS)

    Del Mistro, G.; Stace, A. J.

    1990-08-01

    Molecular dynamics simulations have been performed on the cluster (C 6H 6) 4 with the individual molecules being treated as rigid rotors. Behaviour characteristic of melting is observed at internal temperatures as low as 80 K. It is concluded that the clusters begin to exhibit liquid-like properties when individual molecules acquire sufficient kinetic energy to execute large-ampli- tude motion.

  13. FeCl3·6H2O, a catalyst for the diastereoselective synthesis of cis-isoxazolidines from N-protected δ-hydroxylamino allylic acetates.

    PubMed

    Cornil, Johan; Guérinot, Amandine; Reymond, Sébastien; Cossy, Janine

    2013-10-18

    An ecofriendly and diastereoselective synthesis of cis-3,5-disubstituted isoxazolidines through the FeCl3·6H2O-catalyzed cyclization of δ-hydroxylamino allylic acetates is described. The synthetic potential of these products is highlighted by the preparation of several functionalized 1,3-amino alcohol precursors.

  14. Effect of Crystal Defects on Minority Carrier Diffusion Length in 6H SiC Measured Using the Electron Beam Induced Current Method

    NASA Technical Reports Server (NTRS)

    Tabib-Azar, Massood

    1997-01-01

    We report values of minority carrier diffusion length in n-type 6H SiC measured using a planar Electron Beam Induced Current (EBIC) method. Values of hole diffusion length in defect free regions of n-type 6H SiC, with a doping concentration of 1.7El7 1/cu cm, ranged from 1.46 microns to 0.68 microns. We next introduce a novel variation of the planar method used above. This 'planar mapping' technique measured diffusion length along a linescan creating a map of diffusion length versus position. This map is then overlaid onto the EBIC image of the corresponding linescan, allowing direct visualization of the effect of defects on minority carrier diffusion length. Measurements of the above n-type 6H SiC resulted in values of hole diffusion length ranging from 1.2 micron in defect free regions to below 0.1 gm at the center of large defects. In addition, measurements on p-type 6H SiC resulted in electron diffusion lengths ranging from 1.42 micron to 0.8 micron.

  15. Segregation of Incomplete Achromatopsia and Alopecia Due to PDE6H and LPAR6 Variants in a Consanguineous Family from Pakistan

    PubMed Central

    Pedurupillay, Christeen Ramane J.; Landsend, Erlend Christoffer Sommer; Vigeland, Magnus Dehli; Ansar, Muhammad; Frengen, Eirik; Misceo, Doriana; Strømme, Petter

    2016-01-01

    We report on two brothers with visual impairment, and non-syndromic alopecia in the elder proband. The parents were first-degree Pakistani cousins. Whole exome sequencing of the elder brother and parents, followed by Sanger sequencing of all four family members, led to the identification of the variants responsible for the two phenotypes. One variant was a homozygous nonsense variant in the inhibitory subunit of the cone-specific cGMP phosphodiesterase gene, PDE6H:c.35C>G (p.Ser12*). PDE6H is expressed in the cones of the retina, which are involved in perception of color vision. This is the second report of a homozygous PDE6H:c.35C>G variant causing incomplete achromatopsia (OMIM 610024), thus strongly supporting the hypothesis that loss-of-function variants in PDE6H cause this visual deficiency phenotype. The second variant was a homozygous missense substitution in the lysophosphatidic acid receptor 6, LPAR6:c.188A>T (p.Asp63Val). LPAR6 acts as a G-protein-coupled receptor involved in hair growth. Biallelic loss-of-function variants in LPAR6 cause hypotrichosis type 8 (OMIM 278150), with or without woolly hair, a form of non-syndromic alopecia. Biallelic LPAR6:c.188A>T was previously described in five families from Pakistan. PMID:27472364

  16. Fluoroantimonic acid hexahydrate (HSbF6-6H2O) catalysis: The ring-opening polymerization of epoxidized soybean oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by a super acid, fluroantimonic acid hexahydrate (HSbF6-6H2O), in ethyl acetate was conducted in an effort to develop useful biodegradable polymers. The resulting polymerized ESO (SA-RPESO) were characterized by using infrared (IR...

  17. Ring-opening polymerization of epoxidized soybean oil catalyzed by the superacid, Fluroantimonic acid hexahydrate (HSbF6-6H2O)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by the super acid, fluroantimonic acid hexahydrate (HSbF6-6H2O), in ethyl acetate was conducted. The resulting polymers, SA-RPESO, were characterized using infrared spectroscopy, differential scanning calorimetry, thermogravimetri...

  18. An Analytical Study on Periodically Changing Flow Cells in Groundwater Basins

    NASA Astrophysics Data System (ADS)

    Jiang, X.; Zhao, K. Y.; Wang, J. Z.; Wan, L.; Wang, H.

    2014-12-01

    Current understanding on basin-scale groundwater flow is mainly based on Tóth's (1962, 1963) pioneering study, which assumed that water table is a subdued replica of topography and the annual mean water table controls the pattern of groundwater flow. In fact, water table is driven by dynamic forcing and changes with time. This study modifies the conceptual model of basin-scale groundwater flow by taking the fluctuating water-table into account. For both unit basin and complex basin, water table fluctuates throughout the basin cross-section except for at basin valleys. By the method of separation of variables, we derive the analytical solution of hydraulics head and stream function in the unit basin and the complex basin, and discuss the characteristics of the time-dependent flow cells. For the unit basin, the change in amplitude of hydraulic head fluctuation with depth is studied. For the complex basin, the time-dependent distribution of internal stagnation points is discussed. In addition, the relationship between flowing artesian zone and the fluctuating water-table is discussed. The results of the current study enhance our understanding on the transient nature of basin-scale groundwater flow.

  19. A Study of the Structure of Piagetian Logical and Infralogical Grouping Within the Concrete Operational Period.

    ERIC Educational Resources Information Center

    Dettrick, Graham W.

    This study investigated a problem within the theoretical structure of cognitive development proposed by Jean Piaget, and used the concepts of classification and projective spatial relationships to investigate the nature of attainment and sequencing of three corresponding logical and infralogical groupings according to the models proposed by…

  20. Evaluation and developmental studies of possible active seismic experiments during the post-Apollo period

    NASA Technical Reports Server (NTRS)

    Kovach, R. L.

    1974-01-01

    Seismic velocity studies pertinent to the lunar crust and mantle are briefly summarized. The compressional and shear wave velocities in loose aggregates are discussed along with the effects of temperature on seismic velocity in compacted powders. Abstracts of papers concerning the lunar structure are included.

  1. CBVE: A Study to Measure Its Effectiveness in Kentucky. Final Report. Interim Period 1.

    ERIC Educational Resources Information Center

    Vincent, Roger D.; Cobb, Robert A.

    An interim study was conducted in Kentucky to determine the effectiveness of Competency Based Vocational Education (CBVE) and to compare its effectiveness to that of traditional teaching methodologies. Research surveys of those directly involved in the implementation of CBVE were used to ascertain if CBVE is meeting its self-stated goals.…

  2. From Consciousness to Technology: The Implications of Wave Periodicity Research for Communication Studies.

    ERIC Educational Resources Information Center

    Cooper, Thomas W.

    Attempting to introduce a new viewpoint to communication studies, this speculative and philosophical paper posits technology as an "echo of consciousness." Section one examines technology as a manifestation of attitude, presenting the premise that technologies, consciousness, and systems are not separate components, but products of…

  3. [Neurophysiological and neuroimaging studies for restless legs syndrome and periodic leg movement disorder].

    PubMed

    Happe, S; Paulus, W

    2006-06-01

    The restless legs syndrome (RLS) is a clinical diagnosis based on the four essential criteria defined by the International Restless Legs Syndrome Study Group (IRLSSG). An idiopathic form can be separated from a symptomatic form. Neurophysiological studies have investigated the pathophysiology of the idiopathic RLS or have been used to exclude a symptomatic cause, in particular polyneuropathy. So far cortical excitability changes, corticomotor, somatosensory and auditory pathways, spinal cord excitability, B-wave rhythm and cycling alternating pattern, as well as reflex mechanisms have been investigated by electroencephalography, evoked potentials, Bereitschaftspotentials, nerve conduction and thermal threshold measurements, electromyography, transcranial Doppler sonography, measurements of the spinal flexor reflex as well as neuroimaging techniques. The etiology of the RLS cannot be revealed by these methods, neurophysiological studies in RLS are, however, useful for a better understanding of the pathophysiology and for exclusion of a polyneuropathy or other symptomatic causes. In addition to neurophysiological investigations, small fiber neuropathy, which seems to be a more common finding in RLS patients than expected to date, may need biopsy for confirmation. This review will focus on investigations of the different systems involved with diverse neurophysiological methods.

  4. Pleiotropy in microdeletion syndromes: neurologic and spermatogenic abnormalities in mice homozygous for the p6H deletion are likely due to dysfunction of a single gene.

    PubMed

    Rinchik, E M; Carpenter, D A; Handel, M A

    1995-07-03

    Variability and complexity of phenotypes observed in microdeletion syndromes can be due to deletion of a single gene whose product participates in several aspects of development or can be due to the deletion of a number of tightly linked genes, each adding its own effect to the syndrome. The p6H deletion in mouse chromosome 7 presents a good model with which to address this question of multigene vs. single-gene pleiotropy. Mice homozygous for the p6H deletion are diluted in pigmentation, are smaller than their littermates, and manifest a nervous jerky-gait phenotype. Male homozygotes are sterile and exhibit profound abnormalities in spermiogenesis. By using N-ethyl-N-nitrosourea (EtNU) mutagenesis and a breeding protocol designed to recover recessive mutations expressed hemizygously opposite a large p-locus deletion, we have generated three noncomplementing mutations that map to the p6H deletion. Each of these EtNU-induced mutations has adverse effects on the size, nervous behavior, and progression of spermiogenesis that characterize p6H deletion homozygotes. Because EtNU is thought to induce primarily intragenic (point) mutations in mouse stem-cell spermatogonia, we propose that the trio of phenotypes (runtiness, nervous jerky gait, and male sterility) expressed in p6H deletion homozygotes is the result of deletion of a single highly pleiotropic gene. We also predict that a homologous single locus, quite possibly tightly linked and distal to the D15S12 (P) locus in human chromosome 15q11-q13, may be associated with similar developmental abnormalities in humans.

  5. Structural and photophysical properties of HPPCO (4-hydroxy-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-6-one) derivatives

    NASA Astrophysics Data System (ADS)

    Jeong, Yong-Kwang; Kim, Min-Ah; Lee, Hyo-Sung; Kim, Jong-Moon; Lee, Sung Woo; Kang, Jun-Gill

    2015-01-01

    Proton-substitution effects of 4-hydroxy-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-6-one (HPPCO) on structural and photophysical properties were presented. HPPCO crystallized in the orthorhombic space group Pbca with an intermolecular hydrogen bonding between OH and oxygen atom of the carbonyl. The proton-substituted derivatives, 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl acetate (OPPCA) and 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl benzoate (OPPCB), crystallized in the monoclinic P21/c space group. For OPPCA and OPPCB, a weak interaction between carbonyl oxygen atom in the substituted group and carbon atom in the fused ring was responsible for three-dimensional arrangements. In addition, 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl furan-2-carboxylate (OPPCF), and 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl naphthoate (OPPCN) were also synthesized. HPPCO and the four derivatives excited by ultraviolet (UV) light produced blue emission. Proton substitution of the OH group significantly increased the radiative transitions and moderately decreased the non-radiative transitions. Consequently the luminescence quantum yields of the derivatives enhanced more than 4.6-fold, no matter what the groups were substituted. Structural and optical properties were further determined using density functional theory (DFT) and ZINDO calculations. The planar structure of the pyridocarbazole-fused ring resulted in π → π* electronic transitions within the main frame, with an additional transition from the n(O) of carbonyl to the π* of the main frame. The three excited states that arose from these transitions were responsible for the blue luminescence.

  6. Structural and photophysical properties of HPPCO (4-hydroxy-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-6-one) derivatives.

    PubMed

    Jeong, Yong-Kwang; Kim, Min-Ah; Lee, Hyo-Sung; Kim, Jong-Moon; Lee, Sung Woo; Kang, Jun-Gill

    2015-01-05

    Proton-substitution effects of 4-hydroxy-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-6-one (HPPCO) on structural and photophysical properties were presented. HPPCO crystallized in the orthorhombic space group Pbca with an intermolecular hydrogen bonding between OH and oxygen atom of the carbonyl. The proton-substituted derivatives, 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl acetate (OPPCA) and 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl benzoate (OPPCB), crystallized in the monoclinic P2₁/c space group. For OPPCA and OPPCB, a weak interaction between carbonyl oxygen atom in the substituted group and carbon atom in the fused ring was responsible for three-dimensional arrangements. In addition, 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl furan-2-carboxylate (OPPCF), and 6-oxo-5-phenyl-6H-pyrido[3,2,1-jk]carbazol-4-yl naphthoate (OPPCN) were also synthesized. HPPCO and the four derivatives excited by ultraviolet (UV) light produced blue emission. Proton substitution of the OH group significantly increased the radiative transitions and moderately decreased the non-radiative transitions. Consequently the luminescence quantum yields of the derivatives enhanced more than 4.6-fold, no matter what the groups were substituted. Structural and optical properties were further determined using density functional theory (DFT) and ZINDO calculations. The planar structure of the pyridocarbazole-fused ring resulted in π→π(*) electronic transitions within the main frame, with an additional transition from the n(O) of carbonyl to the π(*) of the main frame. The three excited states that arose from these transitions were responsible for the blue luminescence.

  7. PHOTOMETRIC STUDIES OF THREE NEGLECTED SHORT-PERIOD CONTACT BINARIES GN BOOTIS, BL LEONIS, AND V1918 CYGNI

    SciTech Connect

    Yang, Y.-G.; Dai, H.-F.; Qian, S.-B.

    2013-03-15

    We present new photometry for three short-period contact binaries, GN Boo, BL Leo, and V1918 Cyg, observed from 2008 December to 2012 April using several small telescopes in China. Photometric models were deduced from new observations using the updated Wilson-Devinney Code. The results show that GN Boo and BL Leo are W-type contact binaries, while V1918 Cyg is an A-type one. The mass ratios and fill-out factors are q = 0.320({+-} 0.002) and f = 5.8({+-} 0.1)% for GN Boo, q = 0.476({+-} 0.005) and f = 21.3({+-} 1.1)% for BL Leo, q = 0.264({+-} 0.002), and f = 49.7({+-} 0.7)% for V1918 Cyg, respectively. From the (O - C) curves, it is discovered that the orbital periods of three binaries have varied in a complicated way, i.e., cyclic oscillation for GN Boo, long-term period decrease for BL Leo, and both for V1918 Cyg. The cyclic variations for GN Boo and V1918 Cyg may probably be attributed to the magnetic activity of the primary component or light-time effect due to the third body. Meanwhile, the secular period decreases for BL Leo and V1918 Cyg may result from mass transfer from the primary to the secondary, accompanying the mass and angular momentum loss from the central system. Finally, GN Boo, BL Leo, and V1918 Cyg will evolve into deep contact binaries. Additionally, a statistical study of 37 contact binaries with decreasing periods is given. We obtained the relations of q - f and q - dln P/dt, and preliminarily determined the mass loss rate of dln M/dt from the binary system.

  8. Energy and water balance studies of a snow cover during snowmelt period at a high arctic site

    NASA Astrophysics Data System (ADS)

    Bruland, O.; Maréchal, D.; Sand, K.; Killingtveit, Å.

    The predicted global warming is supposed to have an enhanced effect on the arctic regions. How this will influence the water, carbon dioxide and methane balances in the European arctic tundra is the objective of the EU-funded project ``Understanding Land Surface Physical Processes in the Arctic'' (LAPP), to which where SINTEF is one of several contributors. The snow cover is one of the limiting factors for these exchange processes and knowledge of how it behaves and will behave under a different climate is important. Data collected for water and energy balance studies in an area close to Ny-Ålesund at 79°N at Svalbard are the basis of this study. Measurements during the ablation periods since 1992 show an average air temperature for the periods of 2.1°C, an average incoming shorwave radiation of 230W/m2 and an average measured runoff intensity of 14mm/day with a maximum of 68mm/day. Three models of different complexity are tested in order to simulate the water and energy balance of a snow cover on the arctic tundra. The three models are: a complex numerical model (CROCUS), a simple energy balance model and a temperature index model. The simulations were carried out for the melt periods in 1992 and 1996 as these two periods represent very different meteorological conditions. The results of these simulations exposed weaknesses in all the models. The energy balance model lacks calculation of cold content in the snowpack. This influences both the outgoing longwave radiation and the timing of the melt. Due to the effect of compensating errors in the simulations, CROCUS performed better than the simple energy balance model but also this model has problems with the simulation of outgoing longwave radiation. The temperature index model does not perform well for snowmelt studies in regions were radiation is the main driving energy source for the melt.

  9. Sphenoid sinus fungall ball: a retrospective study over a 10- year period.

    PubMed

    Eloy, Ph; Grenier, J; Pirlet, A; Poirrier, A L; Stephens, J S; Rombaux, Ph

    2013-06-01

    A fungal ball consists of a dense conglomerate of fungal hyphae growing at the surface of the sinus mucosa without tissue infiltration. The maxillary sinus is by far the most commonly involved paranasal sinus cavity followed by the sphenoid sinus. The present study is a retrospective study of 25 consecutive cases treated during the last 10 years in the two hospitals be- longing to the Catholic University of Louvain (CHU Mont-Godinne and UCL Saint Luc). We report the symptomatology, the imaging and discuss the different surgical managements. We conclude that the clinician must have a high index of suspicion when dealing with a unilateral rhinosinusitis persisting despite a maximal and well conducted medical treatment. This is particularly so in elderly women when associated with facial pain and post nasal drip, particularly when the computed tomography shows an unilateral opacity of the sphenoid sinus with or without a sclerosis or an erosion of the bony walls, a polyp in the sphenoethmoidal recess or a hyperdensity mimicking a foreign body. An endonasal endoscopic sphenoidotomy is the treatment of choice in most cases, allowing good ventilation of the sinus and radical removal of all the fungal concretion. A biopsy of the sinus mucosa adjacent to fungal elements is of upmost important to confirm the non- invasiveness of the fungi within the tissue. Antifungal medication is not required in uncomplicated forms. All host factors producing some degree of immunosuppression must be corrected when present and must alert the clinician to rule out any forms of invasive disease.

  10. Scheduled food hastens re-entrainment more than melatonin does after a 6-h phase advance of the light-dark cycle in rats.

    PubMed

    Ángeles-Castellanos, M; Amaya, J M; Salgado-Delgado, R; Buijs, R M; Escobar, C

    2011-08-01

    Circadian desynchrony occurs when individuals are exposed to abrupt phase shifts of the light-dark cycle, as in jet lag. For reducing symptoms and for speeding up resynchronization, several strategies have been suggested, including scheduled exercise, exposure to bright light, drugs, and especially exogenous melatonin administration. Restricted feeding schedules have shown to be powerful entraining signals for metabolic and hormonal daily cycles, as well as for clock genes in tissues and organs of the periphery. This study explored in a rat model of jet lag the contribution of exogenous melatonin or scheduled feeding on the re-entrainment speed of spontaneous general activity and core temperature after a 6-h phase advance of the light-dark cycle. In a first phase, the treatment was scheduled for 5 days prior to the phase shift, while in a second stage, the treatment was simultaneous with the phase advance of the light-dark cycle. Melatonin administration and especially scheduled feeding simultaneous with the phase shift improved significantly the re-entrainment speed. The evaluation of the free-running activity and temperature following the 5-day treatment proved that both exogenous melatonin and specially scheduled feeding accelerated re-entrainment of the SCN-driven general activity and core temperature, respectively, with 7, 5 days (p < 0.01) and 3, 3 days (p < 0.001). The present results show the relevance of feeding schedules as entraining signals for the circadian system and highlight the importance of using them as a strategy for preventing internal desynchrony.

  11. Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period.

    PubMed

    Sousa Filho, F E; da Silva, J H; Saraiva, G D; Abagaro, B T O; Barros, O A; Saraiva, A A F; Viana, B C; Freire, P T C

    2016-03-15

    Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 10(8)years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.

  12. Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period

    NASA Astrophysics Data System (ADS)

    Sousa Filho, F. E.; da Silva, J. H.; Saraiva, G. D.; Abagaro, B. T. O.; Barros, O. A.; Saraiva, A. A. F.; Viana, B. C.; Freire, P. T. C.

    2016-03-01

    Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 108 years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.

  13. Physically based distributed hydrological model calibration based on a short period of streamflow data: case studies in four Chinese basins

    NASA Astrophysics Data System (ADS)

    Sun, Wenchao; Wang, Yuanyuan; Wang, Guoqiang; Cui, Xingqi; Yu, Jingshan; Zuo, Depeng; Xu, Zongxue

    2017-01-01

    Physically based distributed hydrological models are widely used for hydrological simulations in various environments. As with conceptual models, they are limited in data-sparse basins by the lack of streamflow data for calibration. Short periods of observational data (less than 1 year) may be obtained from fragmentary historical records of previously existing gauging stations or from temporary gauging during field surveys, which might be of value for model calibration. However, unlike lumped conceptual models, such an approach has not been explored sufficiently for physically based distributed models. This study explored how the use of limited continuous daily streamflow data might support the application of a physically based distributed model in data-sparse basins. The influence of the length of the observation period on the calibration of the widely applied soil and water assessment tool model was evaluated in four Chinese basins with differing climatic and geophysical characteristics. The evaluations were conducted by comparing calibrations based on short periods of data with calibrations based on data from a 3-year period, which were treated as benchmark calibrations of the four basins, respectively. To ensure the differences in the model simulations solely come from differences in the calibration data, the generalized likelihood uncertainty analysis scheme was employed for the automatic calibration and uncertainty analysis. In the four basins, contrary to the common understanding of the need for observations over a period of several years, data records with lengths of less than 1 year were shown to calibrate the model effectively, i.e., performances similar to the benchmark calibrations were achieved. The models of the wet Jinjiang and Donghe basins could be effectively calibrated using a shorter data record (1 month), compared with the dry Heihe and upstream Yalongjiang basins (6 months). Even though the four basins are very different, when using 1-year or

  14. Studying X-Ray Binaries with High Energy Frequency Quasi-Periodic Oscillations

    NASA Technical Reports Server (NTRS)

    Kaaret, P.; West, Donald K. (Technical Monitor)

    2002-01-01

    The goal of this investigation is to further our understanding of the dynamics of secreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fetus. The main focus of this work has been a multi-year program of simultaneous millisecond X-ray timing and spectral observations carried out with the Rossi X-Ray Timing Explorer (RXTE) to perform the X-ray timing and one of the satellites Asca, BeppoSAX, or Chandra to perform X-ray spectral measurements. With the advent of Chandra, we have extended our work to incLude extragalactic X-ray binaries. We conducted a comprehensive study of the X-ray and radio behavior of the Black Hole Candidate (BHC) X-ray transient XTE J1550-564 using RXTE, Chandra, and the Australian Telescope Compact Array (ATCA). We showed that strong radio emission is associated with major X-ray outbursts involving an X-ray state transition, while a compact radio jet is seen in the low/hard X-ray state found in the outburst decay. Interesting, the total energy required to produce the compact jet may be a substantial fraction of the total accretion energy of the system in that state. We also performed a detailed study of the spectral and timing properties of the decay. In joint RXTE/BeppoSAX observations of the neutron-star X-ray binary Cyg X-2, we discovered a correlation between the timing properties (the frequency of the horizontal branch oscillations) and the properties of a soft, thermal component of the X-ray spectrum. d e showed that more det

  15. Visual search is postponed during the period of the AB: An event-related potential study.

    PubMed

    Lagroix, Hayley E P; Grubert, Anna; Spalek, Thomas M; Di Lollo, Vincent; Eimer, Martin

    2015-08-01

    In the phenomenon known as the attentional blink (AB), perception of the second of two rapidly sequential targets (T2) is impaired when presented shortly after the first (T1). Studies in which T2 consisted of a pop-out search array provided evidence suggesting that visual search is postponed during the AB. In the present work, we used behavioral and electrophysiological measures to test this postponement hypothesis. The behavioral measure was reaction time (RT) to T2; the electrophysiological measure was the onset latency of an ERP index of attentional selection, known as the N2pc. Consistent with the postponement hypothesis, both measures were delayed during the AB. The delay in N2pc was substantially shorter than that in RT, pointing to multiple sources of delay in the chain of processing events, as distinct from the single source postulated in current theories of the AB. Finally, the finding that the N2pc was delayed during the AB strongly suggests that attention is involved in the processing of pop-out search arrays.

  16. An Ultraviolet Study of Non-periodic Variability in Accreting Pre-Main Sequence Stars: UXors

    NASA Astrophysics Data System (ADS)

    Eaton, N. L.; Herbst, W.

    1994-05-01

    Many earlier type (K0 or hotter) pre-main sequence stars are known to occasionally and irregularly fade by as much as 2-3 magnitudes in V. Such excursions occur on timescales of ten to forty days. They include both G-type T Tauri stars and Herbig Ae/Be stars. We propose UX Ori as a prototype for this class of variable stars and refer to them as UXors. We have used archival IUE spectra and a catalog of UBVRI photometry to study the variations of 5 such objects, namely: RY Lup, RY Tau, CO Ori, BF Ori, and UX Ori. The leading hypothesis for explaining their behavior is variable circumstellar obscuration. Relationships between UV spectral line fluxes and equivalent widths and V magnitude are found and displayed. Some shell features in UX Ori and BF Ori switch from absorption to emission during the minima. The equivalent width of these (emission) features [FeII(1,62,63) and MgII(1)] increases as the star fades. Spectral energy distributions (SEDs) covering the interval of 1200 to 8900 angstroms were constructed for several stars at different V magnitude light levels. A strong depression in the SED around 2200 angstroms, caused by iron lines is quite noticeable in UX Ori and BF Ori when the stars are bright. The source and location of the variable obscuring material is discussed.

  17. [Blood lead levels during pregnancy in th the newborn period. Study of the population of Bari].

    PubMed

    Carbone, R; Laforgia, N; Crollo, E; Mautone, A; Iolascon, A

    1998-01-01

    Blood lead levels during pregnancy and in neonates immediately after birth have been evaluated, showing higher values in mothers compared to neonates (5.81 +/- 3.05 vs 4.87 +/- 3.60 micrograms/100 ml) and a positive correlation between maternal and neonatal levels (r = 0.82). On the basis of the results derived from the population examined, it has been observed that 6% of newborns have blood lead levels higher than 10 micrograms/100 ml a value recently identified by the Centers for Disease Control (CDC, Atlanta, USA) as a limit for toxicity in children. Moreover, neonatal Pb levels were higher than those found in infants from 6 to 12 months (4.87 +/- 3.60 vs 2.24 +/- 0.54 micrograms/100 ml). During the first week of life there is a steady decrease of blood lead levels, together with increasing renal lead excretion. This study was carried out at the "Dipartimento di Biomedicina dell'Età Evolutiva" University of Bari, southern Italy.

  18. Periodic Density Functional Theory Study of Water Adsorption on the a-Quartz (101) Surface.

    SciTech Connect

    Bandura, Andrei V.; Kubicki, James D.; Sofo, Jorge O.

    2011-01-01

    Plane wave density functional theory (DFT) calculations have been performed to study the atomic structure, preferred H2O adsorption sites, adsorption energies, and vibrational frequencies for water adsorption on the R-quartz (101) surface. Surface energies and atomic displacements on the vacuum-reconstructed, hydrolyzed, and solvated surfaces have been calculated and compared with available experimental and theoretical data. By considering different initial positions of H2O molecules, the most stable structures of water adsorption at different coverages have been determined. Calculated H2O adsorption energies are in the range -55 to -65 kJ/mol, consistent with experimental data. The lowest and the highest O-H stretching vibrational bands may be attributed to different states of silanol groups on the watercovered surface. The dissociation energy of the silanol group on the surface covered by the adsorption monolayer is estimated to be 80 kJ/mol. The metastable states for the protonated surface bridging O atoms (Obr), which may lead to hydrolysis of siloxane bonds, have been investigated. The calculated formation energy of a Q2 center from a Q3 center on the (101) surface with 2/3 dense monolayer coverage is equal to 70 kJ/mol which is in the range of experimental activation energies for quartz dissolution.

  19. Period Pain

    MedlinePlus

    ... You may also have other symptoms, such as lower back pain, nausea, diarrhea, and headaches. Period pain is not ... Taking a hot bath Doing relaxation techniques, including yoga and meditation You might also try taking over- ...

  20. Six-month low level chlorine dioxide gas inhalation toxicity study with two-week recovery period in rats

    PubMed Central

    2012-01-01

    Background Chlorine dioxide (CD) gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio) is judged as safe on the basis of a battery of toxicological examinations. Methods CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed. Results Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs. Conclusions CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human. PMID:22348507

  1. Periodized wavelets

    SciTech Connect

    Schlossnagle, G.; Restrepo, J.M.; Leaf, G.K.

    1993-12-01

    The properties of periodized Daubechies wavelets on [0,1] are detailed and contrasted against their counterparts which form a basis for L{sup 2}(R). Numerical examples illustrate the analytical estimates for convergence and demonstrate by comparison with Fourier spectral methods the superiority of wavelet projection methods for approximations. The analytical solution to inner products of periodized wavelets and their derivatives, which are known as connection coefficients, is presented, and several tabulated values are included.

  2. The All Sky Automated Survey. The Catalog of Variable Stars. II. 6^h-12^h Quarter of the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Pojmanski, G.

    2003-12-01

    This paper describes the second part of the photometric data from the 9 arcdeg times 9 arcdeg ASAS camera monitoring the whole southern hemisphere in the V-band. Preliminary list of variable stars based on observations obtained since January 2001 is presented. Over 2800000 stars brighter than V=15 mag on 18000 frames were analyzed and 11357 were found to be variable (2685 eclipsing, 907 regularly pulsating, 521 Mira and 7244 other, mostly SR, IRR and LPV stars). Periodic light curves have been classified using the automated algorithm, which now takes into account IRAS infrared fluxes. Basic photometric properties are presented in the tables and some examples of thumbnail light curves are printed for reference. All photometric data are available over the INTERNET at http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas.

  3. Planetary period oscillations in Saturn's magnetosphere: Coalescence and reversal of northern and southern periods in late northern spring

    NASA Astrophysics Data System (ADS)

    Provan, G.; Cowley, S. W. H.; Lamy, L.; Bunce, E. J.; Hunt, G. J.; Zarka, P.; Dougherty, M. K.

    2016-10-01

    We investigate planetary period oscillations (PPOs) in Saturn's magnetosphere using Cassini magnetic field and Saturn kilometric radiation (SKR) data over the interval from late 2012 to the end of 2015, beginning 3 years after vernal equinox and ending 1.5 years before northern solstice. Previous studies have shown that the northern and southern PPO periods converged across equinox from southern summer values 10.8 h for the southern system and 10.6 h for the northern system and near coalesced 1 year after equinox, before separating again with the southern period 10.69 h remaining longer than the northern 10.64 h. We show that these conditions ended in mid-2013 when the two periods coalesced at 10.66 h and remained so until mid-2014, increasing together to longer periods 10.70 h. During coalescence the two systems were locked near magnetic antiphase with SKR modulations in phase, a condition in which the effects of the generating rotating twin vortex flows in the two ionospheres reinforce each other via hemisphere-to-hemisphere coupling. The magnetic-SKR relative phasing indicates the dominance of postdawn SKR sources in both hemispheres, as was generally the case during the study interval. In mid-2014 the two periods separated again, the northern increasing to 10.78 h by the end of 2015, similar to the southern period during southern summer, while the southern period remained fixed near 10.70 h, well above the northern period during southern summer. Despite this difference, this behavior resulted in the first enduring reversal of the two periods, northern longer than southern, during the Cassini era.

  4. High-frequency magnetic oscillations of the organic metal θ-(ET)4ZnBr4(C6H4Cl2) in pulsed magnetic field of up to 81 T

    NASA Astrophysics Data System (ADS)

    Béard, J.; Billette, J.; Suleiman, M.; Frings, P.; Knafo, W.; Scheerer, G. W.; Duc, F.; Vignolles, D.; Nardone, M.; Zitouni, A.; Delescluse, P.; Lagarrigue, J.-M.; Giquel, F.; Griffe, B.; Bruyant, N.; Nicolin, J.-P.; Rikken, G. L. J. A.; Lyubovskii, R. B.; Shilov, G. V.; Zhilyaeva, E. I.; Lyubovskaya, R. N.; Audouard, A.

    2012-09-01

    De Haas-van Alphen oscillations of the organic metal θ-(ET)4ZnBr4(C6H4Cl2) are studied in pulsed magnetic fields up to 81 T. The long decay time of the pulse allows determining reliable field-dependent amplitudes of Fourier components with frequencies up to several kiloteslas. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits. In this model, all the observed frequencies are linear combinations of the frequency linked to the basic orbit α and to the magnetic-breakdown orbit β.

  5. Discovery of a novel 2,3,11,11a-tetrahydro-1H-pyrazino[1,2-b]isoquinoline-1,4(6H)-dione series promoting neurogenesis of human neural progenitor cells.

    PubMed

    Lin, Hong; Fang, Haiyan; Wang, Jamie; Meng, Qinghua; Dai, Xuedong; Wu, Sharon; Luo, Jie; Pu, Dan; Chen, Libo; Minick, Douglas; Arai, Ken; Mandeville, Emiri T; Lo, Eng; Holder, Julie C; Chuang, Tsu Tshen; Zhao, Jing

    2015-09-01

    A novel neurogenic compound (1), discovered from a mouse neural progenitor cell (NPC) screen, showed profound neurogenic effect on human NPCs. Synthesis and SAR of this novel 2,3,11,11a-tetrahydro-1H-pyrazino[1,2-b]isoquinoline-1,4(6H)-dione series are described. Compound 20 is brain penetrable in rodents, and promotes neurogenesis in wild type mice, therefore it is a good tool molecule to study neurogenesis induction as a potential treatment for conditions associated with neurogenesis impairment diseases.

  6. A Study of the X-ray Periodicities in the Remarkable Transient Source Swift J1644+57

    NASA Astrophysics Data System (ADS)

    Griffith, Christopher; Falcone, Abraham

    2016-04-01

    Swift J1644+57 was discovered when it exhibited bright X-ray activity that was believed to be triggered from the infall of a tidally disrupted star near a massive black hole. The observation of a tidal disruption event (TDE) can provide clues to the geometry and physics near the black hole. If a jet forms, as we think happened with Swift J1644+57, it can provide data to study jet creation and the density of matter in a possible accretion disc. We have analyzed Swift X-ray Telescope (XRT) observations of Swift J1644+57 from initial onset to 502 days after TDE onset. We used a Z-transform Discrete Correlation Function (ZDCF) to search for periodicities in the Swift X-ray light curve. We analyzed the X-ray light curve in five time regions, including 0 to 4.5 days after TDE onset, 4.5 to 55 days after TDE onset, 55 to 104 days after TDE onset, 104 to 145 days after TDE onset, and 145 to 502 days after TDE onset. After implementing red and white noise reduction modeling to our ZDCF analysis, we found plausible detections of periodicities. We briefly discuss implications of these periods on the geometry and feeding of the tidal disruption event.

  7. BVRI Photometric Study of the Short Period Solar Type Near-Contact W UMa Binary, FF Vulpeculae

    NASA Astrophysics Data System (ADS)

    Caton, Daniel B.; Samec, Ronald G.; Nyaude, Ropafadzo; Van Hamme, Walter V.

    2016-01-01

    High precision BVRcIc light curves of FF Vul were observed during the Fall, 2015 season at the Dark Sky Observatory 0.81-m reflector of Appalachian State University, and the SARA North 0.91-m reflector at KPNO. It is an eclipsing binary with a period of only 0.444983 (2) d. This is the shortest period of our recently studied Pre Contact W UMa Binary (PCWB's), V2421 Cyg, V1043 Cas, ZZ Eri, V500 Peg, and Mis V1287. Our Binary Maker fits and our Wilson-Devinney solution show that the binary is a near-contact, semidetached binary, i.e., a V1010 Oph type configuration (the more massive component has filled its critical lobe while the secondary component is under-filling). Five times of minimum light were calculated, 3 primary and 2 secondary eclipses from our present observations:HJD I = 2457285.7262 ±0.0002, 2457306.6425 ±0.0002, 2457310.6469 ±0.0002HJD II = 2457279.7222 ±0.0006, 2457280.6124 ±0.0017.The following quadratic ephemerides was determined from all available times of minimum light:JDHelMinI=2457310.6473±0.0007d + 0.4449758±0.0000002 X E -0.00000000006± 0.00000000001 X E2The continuous 20 year period study reveals a period decrease in the orbital period at about the 6 sigma level. Our modeling shows a near-equatorial hot spot on the following side of the secondary component. This is probably due to a matter transfer onto the secondary component. The light curve has a large difference in primary and secondary amplitudes and the light curve solution gives a component temperature difference of more than 1500 K. The solution shows a total secondary eclipse of 23 minutes duration. As expected in binaries of this type, it has a cool spot region on its primary component.

  8. From the mixed valent 6H-Ba 3Ru 5.5+2NaO 9 to the 6H-Ba 3(Ru 1.69C 0.31)(Na 0.95Ru 0.05)O 8.69 oxycarbonate compound

    NASA Astrophysics Data System (ADS)

    Quarez, Eric; Huvé, Marielle; Abraham, Francis; Mentré, Olivier

    2003-07-01

    Ba 3Ru 2NaO 9 single crystals have been prepared by electrosynthesis in molten NaOH. It adopts a 6H perovskite crystal structure, a=5.8645(6) Å, c=14.440(2) Å, space group P6 3/ mmc, Z=2, R1=1.84%, wR2=3.91%. The mean ruthenium valence is 5.5+ for a unique Ru crystallographic site suggesting itinerant electrons within Ru 2O 9 dimers. Previously to our study, a Ru(V)/Ru(VI) charge ordering has been evidenced at 210 K by both single crystal XRD and susceptibility measurements. The resistivity measurement versus temperature performed in the current work shows a brutal R increase at this temperature. Below this temperature, a residual magnetic moment is observed on magnetization plots but has not been observed at 2 K. An additional anomaly is also evidenced on the R versus T plot, at T2=50 K. It is related to a magnetic transition of questionable origin appearing around the same temperature. Attempts to prepare the title compound by solid state reaction lead to a new related-phase. In fact, combined X-ray and neutron diffraction data unambiguously show the presence of CO 2-3 anions in the material. Thus, part of the Ru 2O 9 dimers are replaced by one RuO 5 square pyramid and one CO 3 group leading to the nominal Ba 3(Ru 1.69C 0.31)(Na 0.95Ru 0.05)O 8.69 formula. The carbonates typical vibration bands have been observed by infrared spectroscopy and clearly distinguished from possible BaCO 3 impurity bands. Compared to the ideal 6H-Ba 3Ru 5.5+2NaO 9, the oxycarbonate main characteristic is the ruthenium +5.28 mean valence. Numerically, such a valence can be obtained considering all the dimeric ruthenium with a +5 oxidation number and the RuO 5 and (Na/Ru)O 6 corner sharing octahedra to be +6. The structure has also been refined by Rietveld analysis of powder neutron diffraction data recorded at 20 K. No structural difference is observed at low temperature. The Ba/Na/Ru oxycarbonate shows sensitive modifications of its physical properties as compared to Ba 3Ru 2NaO 9

  9. The plasmapause period of magnetic recovery. Combined study of OGO 4, OGO 5 data and of grounded whistler reception

    NASA Technical Reports Server (NTRS)

    Corcuff, P.; Corcuff, Y.; Carpenter, D. L.; Chappell, C. R.; Vigneron, J.; Kleimenova, N.

    1972-01-01

    The equatorial structure and dynamics of the plasmasphere during the period of magnetic recovery, lasting from the 13 to 23 of September 1968, are studied. The H(+) ions density profiles measured in the night and afternoon sectors by the excentered orbital satellite OGO 5 and L sub p positions of the plasmapause deduced from the VLF records of the polar orbital satellite OGO 4, are included. Electron densities are calculated from the whistlers received at Kerguelen (L approximately 3, 7) and Byrd (L approximately 7), ground stations 150 degrees of longitude apart.

  10. Characterization of molecular beam epitaxy grown β-Nb2N films and AlN/β-Nb2N heterojunctions on 6H-SiC substrates

    NASA Astrophysics Data System (ADS)

    Nepal, Neeraj; Katzer, D. Scott; Meyer, David J.; Downey, Brian P.; Wheeler, Virginia D.; Storm, David F.; Hardy, Matthew T.

    2016-02-01

    β-Nb2N films and AlN/β-Nb2N heterojunctions were grown by molecular beam epitaxy (MBE) on 6H-SiC. The epitaxial nature and β-Nb2N phase were determined by symmetric and asymmetric high-resolution X-ray diffraction (HRXRD) measurements, and were confirmed by grazing incidence diffraction measurements using synchrotron photons. Measured lattice parameters and the in-plane stress of β-Nb2N on 6H-SiC were c = 5.0194 Å, a = 3.0558 Å, and 0.2 GPa, respectively. The HRXRD, transmission electron microscopy, and Raman spectroscopy revealing epitaxial growth of AlN/β-Nb2N heterojunctions have identical orientations with the substrate, abrupt interfaces, and bi-axial stress of 0.88 GPa, respectively. The current finding opens up possibilities for the next generation of high-power devices that cannot be fabricated at present.

  11. Characterization of 6H-SiC JFET Integrated Circuits Over A Broad Temperature Range from -150 C to +500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Krasowski, Michael J.; Chen, Liang-Yu; Prokop, Norman F.

    2009-01-01

    The NASA Glenn Research Center has previously reported prolonged stable operation of simple prototype 6H-SiC JFET integrated circuits (logic gates and amplifier stages) for thousands of hours at +500 C. This paper experimentally investigates the ability of these 6H-SiC JFET devices and integrated circuits to also function at cold temperatures expected to arise in some envisioned applications. Prototype logic gate ICs experimentally demonstrated good functionality down to -125 C without changing circuit input voltages. Cascaded operation of gates at cold temperatures was verified by externally wiring gates together to form a 3-stage ring oscillator. While logic gate output voltages exhibited little change across the broad temperature range from -125 C to +500 C, the change in operating frequency and power consumption of these non-optimized logic gates as a function of temperature was much larger and tracked JFET channel conduction properties.

  12. [V16Sb4O42(H2O){VO(C6H14N2)2}4]: a terminal expansion to a polyoxovanadate archetype.

    PubMed

    Wutkowski, Adam; Näther, Christian; Kögerler, Paul; Bensch, Wolfgang

    2008-03-17

    The charge-neutral antimonatopolyoxovanadium(IV) cluster [V(IV)16Sb(III)4O42(H2O){V(IV)O(C6H14N2)2}4].10H2O.C6H14N2 was obtained under solvothermal conditions. The central cluster fragment, [V(IV) 16Sb(III)4O42], is a derivative of the [V18O42] archetype and is formed by replacing two VO5 polyhedra by two Sb2O5 units. The {V20Sb4} structure expands the {V16Sb4} motif by the addition of four square-pyramidal, terminal VO(1,2-diaminocyclohexane)2 groups. At low temperatures, the magnetic ground state is characterized by four independent S = 1/2 sites.

  13. Nonplanar structure of C6H5SCF3 facilitates πσ∗-mediated photodissociation reaction on the S1 state

    NASA Astrophysics Data System (ADS)

    Kim, So-Yeon; Lee, Jeongmook; Kim, Sang Kyu; Choi, Young S.

    2016-08-01

    Vibrational structure of trifluoromethylthiobenzene (C6H5SCF3) on the S1 state has been investigated by resonance-enhanced two-photon ionization spectroscopy and nature of predissociation dynamics is inferred from homogeneously broadened spectral features. As C6H5SCF3 adopts a nonplanar structure in both the S0 and S1 states, the effective adiabatic barrier generated by avoided crossing of optically-bright bound S1 (ππ∗) and dark-repulsive S2 (πσ∗) surfaces along the reaction coordinate is significantly lowered, giving the S1 lifetime of ∼300 fs. This experiment demonstrates that the molecular structure spanned by the reactive flux near the curve-crossing region dictates reaction rate as well as nonadiabatic transition probability.

  14. A 35-month prospective study on onset of scabies in a psychiatric hospital: discussion on patient transfer and incubation period.

    PubMed

    Makigami, Kuniko; Ohtaki, Noriko; Yasumura, Seiji

    2012-02-01

    This study was conducted to evaluate the risk factors of scabies introduction into a hospital. We addressed the following question: Do patients transferred from other institutions pose a higher risk than patients from the community? From July 2003 to May 2006, a trained physician surveyed the inpatients and staff of a psychiatric hospital (six wards, 300 beds) on a monthly basis. During the study period, specific infection control measures beyond standard precautions, such as prophylactic treatment, were not adopted. There were 333 newly-admitted patients during the study period and among them, 122 were transferred from other institutions. Seven patients were diagnosed with scabies. Two of these patients were infected while in the hospital (secondary infection), thus the number of introduced scabies cases (index cases) was five. Four of the index cases were transferred from other institutions (three from psychiatric hospitals and one from a nursing home). The source of infection for one index case was unexplained. The rate of scabies infection among transferred patients was 3.3% while the infection rate among patients from the community was 0.5%. Therefore, transferred patients pose a higher risk than those from the community. The average time from admission to diagnosis of scabies was 141 days (range 34-313 days). The hospital personnel checked the skin condition of all patients at admission and none of the four patients showed symptoms of scabies.

  15. Draft Genome Sequence of Pseudomonas azotifigens Strain DSM 17556T (6H33bT), a Nitrogen Fixer Strain Isolated from a Compost Pile.

    PubMed

    Busquets, Antonio; Peña, Arantxa; Gomila, Margarita; Mulet, Magdalena; Mayol, Joan; García-Valdés, Elena; Bennasar, Antonio; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Palaniappan, Krishnaveni; Ivanova, Natalia; Schaumberg, Andrew; Pati, Amrita; Reddy, T B K; Nordberg, Henrik; Woyke, Tanja; Klenk, Hans-Peter; Kyrpides, Nikos; Lalucat, Jorge

    2013-10-31

    Pseudomonas azotifigens strain 6H33b(T) is a nitrogen fixer isolated from a hyperthermal compost pile in 2005 by Hatayama and collaborators. Here we report the draft genome, which has an estimated size of 5.0 Mb, exhibits an average G+C content of 66.73%, and is predicted to encode 4,536 protein-coding genes and 100 RNA genes.

  16. Draft Genome Sequence of Pseudomonas azotifigens Strain DSM 17556T (6H33bT), a Nitrogen Fixer Strain Isolated from a Compost Pile

    PubMed Central

    Busquets, Antonio; Peña, Arantxa; Gomila, Margarita; Mulet, Magdalena; Mayol, Joan; García-Valdés, Elena; Bennasar, Antonio; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Palaniappan, Krishnaveni; Ivanova, Natalia; Schaumberg, Andrew; Pati, Amrita; Reddy, T. B. K.; Nordberg, Henrik; Woyke, Tanja; Klenk, Hans-Peter; Kyrpides, Nikos

    2013-01-01

    Pseudomonas azotifigens strain 6H33bT is a nitrogen fixer isolated from a hyperthermal compost pile in 2005 by Hatayama and collaborators. Here we report the draft genome, which has an estimated size of 5.0 Mb, exhibits an average G+C content of 66.73%, and is predicted to encode 4,536 protein-coding genes and 100 RNA genes. PMID:24179119

  17. Vapor-Liquid Equilibrium in the Mixture Trichloromethane CHCl3 + C6H10O Cyclohexanone (EVLM1111, LB5654_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Trichloromethane CHCl3 + C6H10O Cyclohexanone (EVLM1111, LB5654_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

  18. Synthesis of 9,9'-[1,2-ethanediylbis(oxymethylene)]bis-2-amino-1,9-dihydro-6H-purin-6-one, an impurity of acyclovir.

    PubMed

    Suárez, Rosa M; Matía, Maria Paz; Novella, José Luis; Molina, Andres; Cosme, Antonio; Vaquero, Juan José; Alvarez-Builla, Julio

    2012-07-25

    The synthesis of 9,9'-[1,2-ethanediylbis(oxymethylene)]bis-2-amino-1,9-dihydro-6H-purin-6-one, a minor impurity of acyclovir, is described. Starting with commercial N-(9-acetyl-6-oxo-1H-purin-2-yl)acetamide, the process uses an acid catalysed phase transfer catalysis (PTC) process to produce the selective alkylation at the 9 position of the guanine ring.

  19. Hydride-induced anionic cyclization: an efficient method for the synthesis of 6-H-phenanthridines via a transition-metal-free process.

    PubMed

    Chen, Wei-Lin; Chen, Chun-Yuan; Chen, Yan-Fu; Hsieh, Jen-Chieh

    2015-03-20

    A novel procedure for hydride-induced anionic cyclization has been developed. It includes the reduction of a biaryl bromo-nitrile with a nucleophilic aromatic substitution (S(N)Ar). A range of polysubstituted 6-H-phenanthridines were so obtained in moderate to good yield with good substrate tolerance. This method involves a concise transition-metal-free process and was applied to synthesize natural alkaloids.

  20. The International Geophysical Month: Short periods of cooperative study can consolidate the gains of the International Geophysical Year.

    PubMed

    Helliwell, R A; Martin, L H

    1961-12-01

    For convenience, we summarize below some of the main advantages of the IGM concept. 1) Most organizations can mount and support intensive field operations for short periods. 2) High-quality data would be obtained, and the data could be processed more promptly than in long-term projects. 3) Laboratory equipment could in many instances be mnade available for field operations. 4) Top-caliber researchers would be available for field operations. 5) The participation of small research groups and of research workers from government and industry would be fostered. 6) Student participation would improve educational programs in, and attract needed talent to, the geophysical sciences. 7) Ship, satellite, and rocket observations could be scheduled for IGM's. 8) International scientific conferences scheduled to follow IGM's would attract working scientists. It is not suggested that these short-term exercises should replace the long synoptic programs characteristic of the IGY. Rather it is proposed that they supplement and guide any such future long-term program. If adopted, they would produce many data of value for the planning and timing of the International Year of the Quiet Sun. To bring emphasis on special observations during the IQSY, International Geophysical Months might well be scheduled to coincide with the June and December solstices, to be followed by an IGM at an equinoctial period. This would provide periods for concentrated sampling-periods in somewhat the same category as the Regular World Intervals adopted during the IGY. The more elaborate experiments could be confined to the International Geophysical Months, so that only those studies for which continuous observations are essential would be scheduled for the entire period. The duration of an International Geophysical Month would be sufficient for carrying out experiments requiring moving platforms such as ships, rockets, or satellites. It is recommended that every effort be made to schedule the first IGM

  1. Detecting non-uniform period spacings in the Kepler photometry of γ Doradus stars: methodology and case studies

    NASA Astrophysics Data System (ADS)

    Van Reeth, T.; Tkachenko, A.; Aerts, C.; Pápics, P. I.; Degroote, P.; Debosscher, J.; Zwintz, K.; Bloemen, S.; De Smedt, K.; Hrudkova, M.; Raskin, G.; Van Winckel, H.

    2015-02-01

    Context. The analysis of stellar oscillations is one of the most reliable ways to probe stellar interiors. Recent space missions such as Kepler have provided us with an opportunity to study these oscillations with unprecedented detail. For many multi-periodic pulsators such as γ Doradus stars, this led to the detection of dozens to hundreds of oscillation frequencies that could not be found from ground-based observations. Aims: We aim to detect non-uniform period spacings in the Fourier spectra of a sample of γ Doradus stars observed by Kepler. Such detection is complicated by both the large number of significant frequencies in the space photometry and by overlapping non-equidistant rotationally split multiplets. Methods: Guided by theoretical properties of gravity-mode oscillation of γ Doradus stars, we developed a period-spacing detection method and applied it to Kepler observations of a few stars, after having tested the performance from simulations. Results: The application of the technique resulted in the clear detection of non-uniform period spacing series for three out of the five treated Kepler targets. Disadvantages of the technique are also discussed, and include the disability to distinguish between different values of the spherical degree and azimuthal order of the oscillation modes without additional theoretical modelling. Conclusions: Despite the shortcomings, the method is shown to allow solid detections of period spacings for γ Doradus stars, which will allow future asteroseismic analyses of these stars. Based on data gathered with the NASA Discovery mission Kepler and the HERMES spectrograph, which is installed at the Mercator Telescope, operated on the island of La Palma by the Flemish Community at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, and supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of KU Leuven, Belgium, the Fonds National de la

  2. Patterns of nonfatal heroin overdose over a 3-year period: findings from the Australian treatment outcome study.

    PubMed

    Darke, Shane; Williamson, Anna; Ross, Joanne; Mills, Katherine L; Havard, Alys; Teesson, Maree

    2007-03-01

    To determine annual patterns and correlates of nonfatal heroin overdose across 3 years, data were analyzed on 387 heroin users recruited for the Australian Treatment Outcome Study (ATOS), interviewed at 12, 24, and 36 months. A heroin overdose across follow-up was reported by 18.6%, and naloxone had been administered to 11.9%. Annual rates of overdose declined between baseline and 12 months and then remained stable. Previous overdose experience was strongly related to subsequent overdose. Those with a history of overdose before ATOS were significantly more likely to overdose during the study period. In particular, there was a strong association between overdose experience in any 1 year and increased overdose risk in the subsequent year. This is the first study to examine long-term annual trends in nonfatal heroin overdose. While overdose rates declined after extensive treatment, substantial proportions continued to overdose in each year, and this was strongly associated with overdose history.

  3. Spin-polarized Dirac cones and topological nontriviality in a metal-organic framework Ni2C24S6H12.

    PubMed

    Wei, Lin; Zhang, Xiaoming; Zhao, Mingwen

    2016-03-21

    Dirac cones in the band structure make a great contribution to the unique electronic properties of graphene. But the spin-degeneracy of Dirac cones limits the application of graphene in spintronics. Here, using first-principles calculations, we propose a two-dimensional (2D) metal-organic framework (MOF), Ni2C24S6H12, with spin-polarized Dirac cones at the six corners of the Brillouin zone (BZ). Ferromagnetism is quite stable with a high Curie temperature (630 K) as revealed by Monte Carlo simulation within the Ising model. Taking spin-orbit coupling into account, band gaps are opened up at the Dirac point (5.9 meV) and Γ point (10.4 meV) in the BZ, making Ni2C24S6H12 a Chern topological insulator which is implemented for achieving the quantum anomalous Hall effect. These interesting properties enable Ni2C24S6H12 to be a promising candidate material for spintronics device applications.

  4. Organometallic Computational Exercise: Semiempirical Molecular Orbital Calculations on (C6H6)Cr(CO)3 and (B3N3H6Cr(CO)3

    NASA Astrophysics Data System (ADS)

    O'Brien, James F.; Haworth, Daniel T.

    2001-01-01

    A student exercise employing semiempirical molecular orbital calculations in the area of organometallic chemistry is presented. PM3 level calculations are applied to the ground-state structures of C6H6)Cr(CO)3 and (B3N3H6)Cr(CO)3. The calculations are generally successful in computing the known features of the ground-state structures. Comparison of the geometries computed for free and complexed C6H6 and B3N3H6 allow discussion of the reasons for the changes observed. The structures of the transition states for rotation of the rings with respect to Cr(CO)3 are also computed. These results permit calculation of the activation energies for the ring rotations. The activation energies computed at the PM3 level are 0.4 and 18.3 kcal/mol for (C6H6)Cr(CO)3 and (B3N3H6)Cr(CO)3, respectively. These results highlight the differences between the two molecules. Students are encouraged to comment on structural changes in the rings, on the phenomenon of ring rotation in these systems and others such as ferrocene, on the question of the aromaticity of the borazine ring, and on the effect of p back-bonding on the positions of the carbonyl stretching bands in the both complexes.

  5. Characterization of defect levels in semi-insulating 6H-SiC by means of photoinduced transient spectroscopy and modulated photocurrent technique.

    PubMed

    Longeaud, C; Kleider, J P; Kaminski, P; Kozlowski, R; Miczuga, M

    2009-01-28

    Parameters of electrically active defect centres in vanadium-doped 6H silicon carbide (6H-SiC:V) were investigated by means of the photoinduced transient spectroscopy (PITS) and modulated photocurrent (MPC) method. After a short description of the two techniques, experimental results are presented and briefly compared. Our aim is mainly to understand and explain these experimental results. In particular, in the PITS technique a shallow level seems to be at the origin of negative photoconductivity. Besides, in the same temperature range hole and electron levels can be detected at the same time. Finally, the detection of a given level seems to depend on the photon flux used to perform the PITS experiment. As far as the MPC experiment is concerned, it has put into evidence a very efficient shallow level. A numerical calculation was developed to simulate both experiments in order to understand the experimental results. By means of this simulation, we have explained all the phenomena observed experimentally in each technique and we propose a simple model for the distribution of electrically active defect centres in 6H-SiC:V crystals.

  6. Synthesis, spectroscopic characterization and DFT calculations of monohydroxyalkylated derivatives of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione

    NASA Astrophysics Data System (ADS)

    Szyszkowska, Agnieszka; Hęclik, Karol; Trzybiński, Damian; Woźniak, Krzysztof; Klasek, Antonin; Zarzyka, Iwona

    2017-01-01

    Synthesis of new derivatives with an imidazo[1,5-c]quinazoline-3,5-dione ring has been presented. Two new alcohols with the imidazo[1,5-c]quinazoline-3,5-dione ring were obtained and characterized by spectral (1H, 13C NMR, IR and UV) and crystallography methods. A reaction chemoselectivity has been observed with a formation of monohydroxyalkyl derivatives of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione substituted at the 2. nitrogen atom. The absence of derivatives substituted at the 6. nitrogen atom was proven experimentally. The synthesis with chemoselectivity over 99% without control of the substituent effect happens very rarely. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione in the region of the 2. and the 6. nitrogen atoms. Quantum-mechanical DFT calculations proved to be very useful to explain the reason of selectivity reaction of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione with oxiranes.

  7. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats: Insights from a case study in Tillamook Bay, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2012-05-01

    This study validates the ecological relevance of estuarine habitat types to the benthic macrofaunal community and, together with previous similar studies, suggests they can serve as elements in ecological periodic tables of benthic macrofaunal usage in the bioregion. We compared benthic macrofaunal Bray-Curtis similarity and the means of eight benthic macrofaunal community measures across seven habitat types in Tillamook Bay, Oregon, USA: intertidal eelgrass (Zostera marina), dwarf eelgrass (Zostera japonica), oyster (Crassostrea gigas) ground culture, burrowing mud shrimp (Upogebia pugettensis), burrowing ghost shrimp (Neotrypaea californiensis), sand and subtidal. Benthic macrofaunal Bray-Curtis similarity differed among all the habitats except ghost shrimp and sand. The habitat rank order on mean benthic macrofaunal species richness, abundance and biomass was dwarf eelgrass ≈ oyster ≥ mud shrimp ≈ eelgrass > sand ≈ ghost shrimp ≈ subtidal. The benthic macrofaunal habitat usage pattern in Tillamook Bay was, with a few exceptions, similar to that in two other US Pacific Northwest estuaries. The exceptions indicate variants of eelgrass and ghost shrimp habitat that differ in benthic macrofaunal usage perhaps due to differences in the coarseness of the sand fraction of the sediments in which they live. The similarities indicate periodic benthic macrofaunal usage patterns across the other habitat types extend over a wider geographic scale and range of environmental conditions than previously known.

  8. Choice of fluid therapy in patients of craniopharyngioma in the perioperative period: A hospital-based preliminary study

    PubMed Central

    Mukherjee, K. K.; Dutta, Pinaki; Singh, Apinderpreet; Gupta, Prakamya; Srinivasan, Anand; Bhagat, Hemant; Mathuriya, S. N.; Shah, Viral N.; Bhansali, Anil

    2014-01-01

    Background: Electrolyte imbalance and acute diabetes insipidus (DI) are the most common complications in patients undergoing craniopharyngioma surgery. Improper management of water and electrolyte imbalance is common cause of morbidity and mortality. Data is sparse and controversial regarding the choice of fluid therapy in this population during perioperative period. Methods: In this retrospective-prospective study involving 73 patients (58 retrospective), the type of fluid therapy was correlated with occurrence of hypernatremia, hyponatremia, DI, morbidity, and mortality. In the retrospective study, 48 patients received normal saline and 10 received mixed fluids as per the prevailing practice. In the prospective group, five patients each received normal saline, half normal saline, and 5% dextrose randomly. Results: The sodium values were significantly higher in first 48 h in the group that received normal saline compared with other groups (P < 0.001). The use of normal saline was associated with higher incidence of hypernatremia, DI, and mortality (P = 0.05), while the group that received 5% dextrose was associated with hyponatremia, hypoglycemia, and seizures. There was no perioperative hypotension with use of any of the fluids. Conclusion: Our results indicate half normal saline was fluid of choice with diminished incidence of water and electrolyte abnormalities without increase in mortality during postoperative period. PMID:25101200

  9. Solubility of Two Root-End Filling Materials over Different Time Periods in Synthetic Tissue Fluid: a Comparative Study

    PubMed Central

    Shojaee, Nooshin Sadat; Sahebi, Safoora; Karami, Elahe; Sobhnamayan, Fereshte

    2015-01-01

    Statement of the Problem Insolubility is an important criterion for an ideal root-end filling material to both prevent any microleakage between the root canal and the periradicular space and provide sealing ability. Purpose Many recent studies have shown that mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) have acceptable sealing ability. The purpose of this in vitro study was to evaluate the solubility of these root-end filling materials. Materials and Method Forty stainless steel ring moulds with an internal diameter of 10±1 mm and a height of 2±0.1 mm were selected. Samples of MTA and CEM were mixed according to the manufacturer’s instructions and inserted into the moulds. The specimens were divided into 4 experimental groups and kept in synthetic tissue fluid (STF) for 2 different time periods (7 and 28 days). The control group contained 8 empty rings. The moulds’ weights were recorded before and after immersion in STF. The changes in the weight of the samples were measured and compared using a two- way ANOVA test at a significance level of 5%. Specimens were evaluated with scanning electron microscopy (SEM) at a magnification of 500×. Results There was no significant difference in weight changes between MTA and CEM samples (p> 0.05). Conclusion MTA and CEM have similar solubility in STF in different time periods. PMID:26331148

  10. Insulin receptor substrate-2 phosphorylation is necessary for protein kinase C zeta activation by insulin in L6hIR cells.

    PubMed

    Oriente, F; Formisano, P; Miele, C; Fiory, F; Maitan, M A; Vigliotta, G; Trencia, A; Santopietro, S; Caruso, M; Van Obberghen, E; Beguinot, F

    2001-10-05

    We have investigated glycogen synthase (GS) activation in L6hIR cells expressing a peptide corresponding to the kinase regulatory loop binding domain of insulin receptor substrate-2 (IRS-2) (KRLB). In several clones of these cells (B2, F4), insulin-dependent binding of the KRLB to insulin receptors was accompanied by a block of IRS-2, but not IRS-1, phosphorylation, and insulin receptor binding. GS activation by insulin was also inhibited by >70% in these cells (p < 0.001). The impairment of GS activation was paralleled by a similarly sized inhibition of glycogen synthase kinase 3 alpha (GSK3 alpha) and GSK3 beta inactivation by insulin with no change in protein phosphatase 1 activity. PDK1 (a phosphatidylinositol trisphosphate-dependent kinase) and Akt/protein kinase B (PKB) activation by insulin showed no difference in B2, F4, and in control L6hIR cells. At variance, insulin did not activate PKC zeta in B2 and F4 cells. In L6hIR, inhibition of PKC zeta activity by either a PKC zeta antisense or a dominant negative mutant also reduced by 75% insulin inactivation of GSK3 alpha and -beta (p < 0.001) and insulin stimulation of GS (p < 0.002), similar to Akt/PKB inhibition. In L6hIR, insulin induced protein kinase C zeta (PKC zeta) co-precipitation with GSK3 alpha and beta. PKC zeta also phosphorylated GSK3 alpha and -beta. Alone, these events did not significantly affect GSK3 alpha and -beta activities. Inhibition of PKC zeta activity, however, reduced Akt/PKB phosphorylation of the key serine sites on GSK3 alpha and -beta by >80% (p < 0.001) and prevented full GSK3 inactivation by insulin. Thus, IRS-2, not IRS-1, signals insulin activation of GS in the L6hIR skeletal muscle cells. In these cells, insulin inhibition of GSK3 alpha and -beta requires dual phosphorylation by both Akt/PKB and PKC zeta.

  11. Hydrogen-bond-directed assemblies of [La(18-crown-6)(H2O)4](BiCl6)·3H2O and [Nd(18-crown-6)(H2O)4](BiCl6)·3.5H2O regulated by different symmetries

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Yong; Li, Jian; Zeng, Ying; Wen, He-Rui; Du, Zi-Yi

    2016-12-01

    The reactions of La2O3 or Nd2O3 with BiCl3 and 18-crown-6 in the presence of excessive hydrochloric acid afforded two ion-pair compounds, namely [La(18-crown-6)(H2O)4](BiCl6)·3H2O (1) and [Nd(18-crown-6)(H2O)4](BiCl6)·3.5H2O (2). Although these two compounds contain similar building blocks, they exhibit two distinct hydrogen-bonded networks, which are mainly induced by the slightly different geometries of their large-sized cationic [Ln(18-crown-6)(H2O)4]3+ components.

  12. Brownian dynamics studies on DNA gel electrophoresis. I. Numerical method and ``periodic'' behavior of elongation-contraction motions

    NASA Astrophysics Data System (ADS)

    Azuma, Ryuzo; Takayama, Hajime

    2002-10-01

    The dynamics of a DNA molecule which is undergoing constant field gel electrophoresis (CFGE) is studied by a Brownian dynamics simulation method we have developed. In the method a DNA molecule is modeled as a chain of spherical electrolyte beads and the gel as a three-dimensional array of immobile beads. With the constraint for the separation of each pair of bonded beads to be less than a certain fixed value, as well as with the excluded volume effect, the simultaneous Langevin equations of motion for the beads are solved by means of the Lagrangian multiplier method. The resultant mobilities μ as a function of electric field coincide satisfactorily with the corresponding experimental results, once the time, the length, and the field of the simulation are properly scaled. In relatively strong fields "periodic" behavior is found in the chain dynamics and is examined through the time evolution of the radius of the longer principal axis, Rl(t). It is found that the mean width of a peak in Rl(t), or a period of one elongation-contraction process of the chain, is proportional to the number of beads in the chain, M, while the mean period between two such adjacent peaks is independent of M for large M. These results, combined with the observation that the chain moves to the field direction by the distance proportional to M in each elongation-contraction motion, yield the saturation of mobility for large M. This explains the reason that CFGE cannot separate DNA according to their size L(∝M) for large L.

  13. Structural phase transition causing anomalous photoluminescence behavior in perovskite (C{sub 6}H{sub 11}NH{sub 3}){sub 2}[PbI{sub 4}

    SciTech Connect

    Yangui, A.; Pillet, S.; Mlayah, A.; Lusson, A.; Bouchez, G.; Boukheddaden, K. E-mail: kbo@physique.uvsq.fr; Triki, S.; Abid, Y. E-mail: kbo@physique.uvsq.fr

    2015-12-14

    Optical and structural properties of the organic-inorganic hybrid perovskite-type (C{sub 6}H{sub 11}NH{sub 3}){sub 2}[PbI{sub 4}] (abbreviated as C{sub 6}PbI{sub 4}) were investigated using optical absorption, photoluminescence (PL), and x-ray diffraction measurements. Room temperature, optical absorption measurements, performed on spin-coated films of C{sub 6}PbI{sub 4}, revealed two absorption bands at 2.44 and 3.21 eV. Upon 325 nm (3.815 eV) laser irradiation, strong green PL emission peaks were observed at 2.41 eV (P1) and 2.24 eV (P2) and assigned to free and localized excitons, respectively. The exciton binding energy was estimated at 356 meV. At low temperature, two additional emission bands were detected at 2.366 eV (P3) and a large band (LB) at 1.97 eV. The former appeared only below 40 K and the latter emerged below 130 K. The thermal dependence of the PL spectra revealed an abnormal behavior accompanied by singularities in the peak positions and intensities at 40 and 130 K. X-ray diffraction studies performed on powder and single crystals as a function of temperature evidenced significant changes of the interlayer spacing at 50 K and ∼138 K. Around 138 K, a commensurate to incommensurate structural phase transition occurred on cooling. It involves a symmetry breaking leading to a distortion of the PbI{sub 6} octahedron. The resulting incommensurate spatial modulation of the Pb–I distances (and Pb–I–Pb angles) causes a spatial modulation of the band gap, which is at the origin of the emergence of the LB below ∼130 K and the anomalous behavior of the position of P1 below 130 K. The change of the interlayer spacing in the 40-50 K range may in turn be related to the significant decrease of the intensity of P2 and the maximum emission of the LB. These results underline the intricate character of the structural and the PL properties of the hybrid perovskites; understanding such properties should benefit to the design of optoelectronic devices with

  14. Structural phase transition causing anomalous photoluminescence behavior in perovskite (C6H11NH3)2[PbI4].

    PubMed

    Yangui, A; Pillet, S; Mlayah, A; Lusson, A; Bouchez, G; Triki, S; Abid, Y; Boukheddaden, K

    2015-12-14

    Optical and structural properties of the organic-inorganic hybrid perovskite-type (C6H11NH3)2[PbI4] (abbreviated as C6PbI4) were investigated using optical absorption, photoluminescence (PL), and x-ray diffraction measurements. Room temperature, optical absorption measurements, performed on spin-coated films of C6PbI4, revealed two absorption bands at 2.44 and 3.21 eV. Upon 325 nm (3.815 eV) laser irradiation, strong green PL emission peaks were observed at 2.41 eV (P1) and 2.24 eV (P2) and assigned to free and localized excitons, respectively. The exciton binding energy was estimated at 356 meV. At low temperature, two additional emission bands were detected at 2.366 eV (P3) and a large band (LB) at 1.97 eV. The former appeared only below 40 K and the latter emerged below 130 K. The thermal dependence of the PL spectra revealed an abnormal behavior accompanied by singularities in the peak positions and intensities at 40 and 130 K. X-ray diffraction studies performed on powder and single crystals as a function of temperature evidenced significant changes of the interlayer spacing at 50 K and ∼138 K. Around 138 K, a commensurate to incommensurate structural phase transition occurred on cooling. It involves a symmetry breaking leading to a distortion of the PbI6 octahedron. The resulting incommensurate spatial modulation of the Pb-I distances (and Pb-I-Pb angles) causes a spatial modulation of the band gap, which is at the origin of the emergence of the LB below ∼130 K and the anomalous behavior of the position of P1 below 130 K. The change of the interlayer spacing in the 40-50 K range may in turn be related to the significant decrease of the intensity of P2 and the maximum emission of the LB. These results underline the intricate character of the structural and the PL properties of the hybrid perovskites; understanding such properties should benefit to the design of optoelectronic devices with targeted properties.

  15. Changing picture of acute kidney injury in pregnancy: Study of 259 cases over a period of 33 years.

    PubMed

    Prakash, J; Pant, P; Prakash, S; Sivasankar, M; Vohra, R; Doley, P K; Pandey, L K; Singh, U

    2016-01-01

    The incidence of acute kidney injury (AKI) in pregnancy is declining in developing countries but still remains a major cause of maternal and fetal morbidity and mortality. The aim of the study was to analyze the changing trends in pregnancy related AKI (PR-AKI) over a period of thirty-three years. Clinical characteristics of PR-AKI with respect to incidence, etiology and fetal and maternal outcomes were compared in three study periods, namely 1982-1991,1992-2002 and 2003-2014. The incidence of PR-AKI decreased to 10.4% in 1992-2002, from 15.2% in 1982-1991, with declining trend continuing in 2003-2014 (4.68%).Postabortal AKI decreased to 1.49% in 2003-2014 from 9.4% in 1982-1991of total AKI cases. The AKI related to puerperal sepsis increased to 1.56% of all AKI cases in 2003-2014 from 1.4% in 1982-1991. Preeclampsia/eclampsia associated AKI decreased from 3.5% of total AKI cases in 1982-1991 to 0.54% in 2003-2014. Pregnancy associated - thrombotic microangiopathy and acute fatty liver of pregnancy were uncommon causes of AKI. Hyperemesis gravidarum associated AKI was not observed in our study. Incidence of renal cortical necrosis (RCN) decreased to 1.4% in 2003-2014 from 17% in 1982-1991.Maternal mortality reduced to 5.79% from initial high value 20% in 1982-1991. The progression of PR-AKI to ESRD decreased to1.4% in 2003-2014 from 6.15% in 1982-1991. The incidence of PR-AKI has decreased over last three decades, mainly due to decrease in incidence of postabortal AKI. Puerperal sepsis and obstetric hemorrhage were the major causes of PR-AKI followed by preeclampsia in late pregnancy. Maternal mortality and incidence and severity of RCN have significantly decreased in PR-AKI. The progression to CKD and ESRD has decreased in women with AKI in pregnancy in recent decade. However, the perinatal mortality did not change throughout study period.

  16. Changing picture of acute kidney injury in pregnancy: Study of 259 cases over a period of 33 years

    PubMed Central

    Prakash, J.; Pant, P.; Prakash, S.; Sivasankar, M.; Vohra, R.; Doley, P. K.; Pandey, L. K.; Singh, U.

    2016-01-01

    The incidence of acute kidney injury (AKI) in pregnancy is declining in developing countries but still remains a major cause of maternal and fetal morbidity and mortality. The aim of the study was to analyze the changing trends in pregnancy related AKI (PR-AKI) over a period of thirty-three years. Clinical characteristics of PR-AKI with respect to incidence, etiology and fetal and maternal outcomes were compared in three study periods, namely 1982-1991,1992-2002 and 2003-2014. The incidence of PR-AKI decreased to 10.4% in 1992-2002, from 15.2% in 1982-1991, with declining trend continuing in 2003-2014 (4.68%).Postabortal AKI decreased to 1.49% in 2003-2014 from 9.4% in 1982-1991of total AKI cases. The AKI related to puerperal sepsis increased to 1.56% of all AKI cases in 2003-2014 from 1.4% in 1982-1991. Preeclampsia/eclampsia associated AKI decreased from 3.5% of total AKI cases in 1982-1991 to 0.54% in 2003-2014. Pregnancy associated – thrombotic microangiopathy and acute fatty liver of pregnancy were uncommon causes of AKI. Hyperemesis gravidarum associated AKI was not observed in our study. Incidence of renal cortical necrosis (RCN) decreased to 1.4% in 2003-2014 from 17% in 1982-1991.Maternal mortality reduced to 5.79% from initial high value 20% in 1982-1991. The progression of PR-AKI to ESRD decreased to1.4% in 2003-2014 from 6.15% in 1982-1991. The incidence of PR-AKI has decreased over last three decades, mainly due to decrease in incidence of postabortal AKI. Puerperal sepsis and obstetric hemorrhage were the major causes of PR-AKI followed by preeclampsia in late pregnancy. Maternal mortality and incidence and severity of RCN have significantly decreased in PR-AKI. The progression to CKD and ESRD has decreased in women with AKI in pregnancy in recent decade. However, the perinatal mortality did not change throughout study period. PMID:27512298

  17. Periodic Polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Edwin

    2013-03-01

    Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

  18. Absorption spectra of vanadyl ion doped in MgNH 4PO 4·6H 2O (struvite) crystal

    NASA Astrophysics Data System (ADS)

    Agarwal, O. P.; Chand, Prem

    1984-10-01

    Results of Electron Paramagnetic Resonance (EPR) and optical absorption studies of VO 2+ ion doped in struvite at room liquid nitrogen temperatures are reported. Three preferential V= O bond directions in the crystal have been identified. The optical and EPR data have shown the formation of NH 4(PO 4VO(H 2O) 5 complex in the crystal as a result of VO 2+ doping. Correlating the optical and EPR data the molecular orbital coefficients are also obtained and discussed.

  19. Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

    NASA Astrophysics Data System (ADS)

    Niemi, J. V.; Saarikoski, S.; Tervahattu, H.; Mäkelä, T.; Hillamo, R.; Vehkamäki, H.; Sogacheva, L.; Kulmala, M.

    2006-11-01

    Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode (PM1~16 µg m-3, backward air mass trajectories from south-east), intermediate period (PM1~5 µg m-3, backtrajectories from north-east) and clean period (PM1~2 µg m-3, backtrajectories from north-west/north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2-1 and PM1-3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2-1 samples were 1) soot and 2) (ammonium)sulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2-1 samples were 0-12% and 83-97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high (26-48%) in the PM1-3.3 and PM3.3-11 samples, while the PM0.2-1 and PM1-3.3 samples contained elevated proportions of silicates (22-33%), metal oxides/hydroxides (1-9%) and tar balls (1-4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1-3.3 samples contained mainly sea salt particles (67-89%) with a variable rate of Cl substitution (mainly by NO3-). During the intermediate period, the PM1-3.3 sample contained porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments (probably also biological origin) were highest

  20. The first multi-color photometric study of the short-period contact eclipsing binary DE Lyn

    NASA Astrophysics Data System (ADS)

    Hashimoto, Amanda; Zhang, Liyun; Han, Xianming L.; Lu, Hongpeng; Wang, Daimei

    2016-05-01

    We observed the contact eclipsing binary of DE Lyn using SARA 0.9 m telescope at Kitt Peak National Observatory on February 9, 11, and 27, 2015. In this study, we obtained the first full phase coverage BVRI CCD light curves, analyzed the orbital period variation, and extracted the orbital parameters. We calculated the linear and quadratic ephemeris, and thereby found that DE Lyn has a decreasing orbital period rate of - 5.1(± 0.4) × 10-7 days/year. We assume this decreasing trend is the result of the more massive component (secondary) transferring mass to the less massive component (primary), and we obtained a mass transfer rate of dm / dt = 7.06 ×10-7M⊙ /year . By using the updated Wilson & Devinney program, we found the orbital parameters of DE Lyn, which, in turn, enabled us to calculate the low degree of contact factor as f = 9.02(± 0.01)%. In the future, its degree of contact will continue to increase and will evolve into an over-contact system.

  1. The first multi-color photometric study of the short-period contact Eclipsing Binary DE Lyn

    NASA Astrophysics Data System (ADS)

    Hashimoto, Amanda; Zhang, Liyun; Han, Xianming L.; Hongpeng, Lu; Wang, Daimei

    2016-01-01

    We observed the contact eclipsing binary of DE Lyn using SARA 0.9 meter telescope at Kitt Peak National Observatory on February 9, 11, and 27, 2015. In this study, we obtained the first full phase coverage BVRI CCD light curves, analyzed the orbital period variation, and extracted the orbital parameters. We calculated the linear and quadratic ephemeris, and thereby found that DE Lyn has a decreasing orbital period rate of -5.1(±0.4)×10-7 days/year. We believe this decreasing trend is the result of the more massive component (secondary) transferring mass to the less massive component (primary), and we obtained a mass transfer rate of dm/dt = 7.06×10-7M⊙/year. By using the updated Wilson & Devinney program, we found the orbital parameters of DE Lyn, which, in turn, enabled us to calculate the low degree of contact factor as f = 9.02(± 0.01)%. Its degree of contact will continue to increase and will evolve into an over-contact system.

  2. Light trapping efficiency of periodic and quasiperiodic back-reflectors for thin film solar cells: A comparative study

    NASA Astrophysics Data System (ADS)

    Micco, A.; Ricciardi, A.; Pisco, M.; La Ferrara, V.; Mercaldo, L. V.; Delli Veneri, P.; Cutolo, A.; Cusano, A.

    2013-08-01

    Recently, great efforts have been carried out to design optimized metallic nano-grating back-reflectors to improve the light absorption in thin film solar cells. In this work, we compare the performances of deterministic aperiodic backreflectors in the form of 1-D nanogratings based on the generalized Fibonacci deterministic aperiodic sequence with a standard periodic one. The case of study here analyzed relies on a realistic solar cell model, where light absorption is evaluated only in the intrinsic region of an amorphous silicon P-I-N junction. We found that the results of comparison are strongly influenced by the amorphous silicon extinction coefficient within the near-infrared wavelength range, where most photonic-plasmonic modes (responsible for the light absorption enhancement typically observed when structured metal nanogratings are employed) are excited. In particular, with device-grade hydrogenated amorphous silicon, we demonstrate that Fibonacci-like backreflectors are able to provide an absorption enhancement of about 4% and 20% with respect to periodic and flat metallic backreflectors, respectively. We also found that aperiodic gratings guarantee better results in terms of robustness to the incident angle of the incoming radiation. Overall, our results confirm that aperiodic geometries are effectively able to offer some intriguing perspectives to enhance light trapping capability in thin film solar cells especially thanks to the large set of patterns employable to enable a proper design of resonant modes number and their spectral locations.

  3. Recurrence rates of bipolar disorder during the postpartum period: a study on 276 medication-free Italian women.

    PubMed

    Maina, Giuseppe; Rosso, Gianluca; Aguglia, Andrea; Bogetto, Filippo

    2014-10-01

    The postpartum period is considered a time of heightened vulnerability to bipolar disorder. The primary goal of this study was to examine the frequency and the polarity of postpartum episodes in a clinical sample of women with bipolar disorder who were medication-free during their pregnancies. In addition, we sought to examine whether there are differences in terms of clinical features of bipolar disorder between women with and without postpartum episodes. Lastly, we analyzed the potential relationship between polarity of the postpartum episodes and clinical features of bipolar disorder. The presence/absence of postpartum episodes and their characteristics were obtained from medical records of 276 women with bipolar disorder who were medication-free during their pregnancies. Two hundred seven women (75.0 %) had a history of one or more postpartum mood episodes: depressive (79.7 %), (hypo)manic (16.4 %), or mixed episodes (3.9 %). Psychotic symptoms during postpartum episodes were associated with depression in 37 (22.4 %) patients, with mania in 19 (67.8 %) patients, and with mixed episodes in 7 (87.5 %) patients. Postpartum manic and mixed episodes were significantly associated with type I disorder and with psychotic features. Our findings indicate high risk of clinically ascertained mood episodes during postpartum period in bipolar women who are not treated during pregnancy.

  4. A Study on The Incidence of Neural Tube Defects in A Tertiary Care Hospital Over A Period of Five Years

    PubMed Central

    Subramanian, Manickam; Rajilarajendran, Hannahsugirthabai; Ramanujam, Sailatha; Saktivel, Sathiya; Sivaanandam, Renuka

    2015-01-01

    Introduction Several congenital malformations affect developing fetuses, among which Neural tube defect (NTD) is most common. Folic acid supplementation brought decline in the incidence of NTDs. The present study aims at finding the incidence of NTDs in a tertiary care hospital and compares the results with the similar Indian studies published earlier. Materials and Methods The study was done at Chettinad Hospital & Research Institute (CHRI), Kelambakkam. The total number of deliveries was recorded for a period of five years from 2009 to 2013. Fetuses which were still born with neural defect were collected and observed in detail externally for the sex, type of NTD and other associated anomalies. Indian studies published between 1987 and 2014 reporting the incidence of NTDs among the births occurred were retrieved from the Internet and their various observations were used for comparison. Results The number of deliveries conducted between 2009 and 2013 at CHRI was 3220. Of these, babies born with NTDs were nine (5 males and 4 females). The incidence of fetuses with meroanencephaly, holoanencephaly, craniorachischisis, encephalocele and myelocele were 0.62, 0.62, 0.93, 0.31 and 0.31 per 1000 births respectively. Overall incidence of NTDs in the present study was 2.79/1000 births. Fetuses with NTDs also had the following anomalies – Club foot, cleft lip and palate and exomphalos. Conclusion Comparing the results with the previous studies it is clearly evident that the incidence of NTDs have significantly reduced from 11.42/1000 births to 2.79/1000 births. In most of the previous studies NTDs had a female preponderance whereas present study has a male preponderance.In older studies, spina bifida was the most common NTDs followed by anencephaly. But in the present study anencephaly was the common NTD than spina bifida. Incidence of NTDs has reduced due to various reasons like prenatal screening for fetal anomalies and folic acid supplementation. PMID:26393168

  5. Determination of Normal Ranges of Shock Index and Other Haemodynamic Variables in the Immediate Postpartum Period: A Cohort Study

    PubMed Central

    Nathan, Hannah L.; Cottam, Kate; Hezelgrave, Natasha L.; Seed, Paul T.; Briley, Annette; Bewley, Susan; Chappell, Lucy C.; Shennan, Andrew H.

    2016-01-01

    Objective To determine the normal ranges of vital signs, including blood pressure (BP), mean arterial pressure (MAP), heart rate (HR) and shock index (SI) (HR/systolic BP), in the immediate postpartum period to inform the development of robust obstetric early warning scores. Study Design We conducted a secondary analysis of a prospective observational cohort study evaluating vital signs collected within one hour following delivery in women with estimated blood loss (EBL) <500ml (316 women) delivering at a UK tertiary centre over a one-year period. Simple and multiple linear regression were used to explore associations of demographic and obstetric factors with SI. Results Median (90% reference range) was 120 (100–145) for systolic BP, 75 (58–90) for diastolic BP, 90 (73–108) for MAP, 81 (61–102) for HR, and 0.66 (0.52–0.89) for SI. Third stage Syntometrine® administration was associated with a 0.03 decrease in SI (p = 0.035) and epidural use with a 0.05 increase (p = 0.003). No other demographic or obstetric factors were associated with a change in shock index in this cohort. Conclusion This is the first study to determine normal ranges of maternal BP, MAP, HR and SI within one hour of birth, a time of considerable haemodynamic adjustment, with minimal effect of demographic and obstetric factors demonstrated. The lower 90% reference point for systolic BP and upper 90% reference point for HR correspond to triggers used to recognise shock in obstetric practice, as do the upper 90% reference points for systolic and diastolic BP for obstetric hypertensive triggers. The SI upper limit of 0.89 in well postpartum women supports current literature suggesting a threshold of 0.9 as indicating increased risk of adverse outcomes. PMID:27997586

  6. Age, time period, and birth cohort differences in self-esteem: Reexamining a cohort-sequential longitudinal study.

    PubMed

    Twenge, Jean M; Carter, Nathan T; Campbell, W Keith

    2016-12-08

    Orth, Trzesniewski, and Robins (2010) concluded that the nationally representative Americans' Changing Lives (ACL) cohort-sequential study demonstrated moderate to large age differences in self-esteem, and no birth cohort (generational) differences in the age trajectory. In a reanalysis of these data using 2 different statistical techniques, we find significant increases in self-esteem that could be attributed to birth cohort or time period. First, hierarchical linear modeling analyses with birth cohort as a continuous variable (vs. the multiple group formulation used by Orth et al.) find that birth cohort has a measurable influence on self-esteem through its interaction with age. Participants born in later years (e.g., 1960) were higher in self-esteem and were more likely to increase in self-esteem as they aged than participants born in earlier years (e.g., 1920). However, the estimated age trajectory up to age 60 is similar in Orth et al.'s results and in the results from our analyses including cohort. Second, comparing ACL respondents of the same age in 1986 versus 2002 (a time-lag design) yields significant birth cohort differences in self-esteem, with 2002 participants of the same age higher in self-esteem than those in 1986. Combined with some previous studies finding significant increases in self-esteem and positive self-views over time, these results suggest that cultural change in the form of cohort and time period cannot be ignored as influences in cross-sectional and longitudinal studies. (PsycINFO Database Record

  7. Synthesis, characterization and antioxidant activity of a novel organic-inorganic hybrid material trans-2,5-dimethylpiperazine-1,4-diium pentachlorobismuthate(III): [C6H16N2]BiCl5

    NASA Astrophysics Data System (ADS)

    Essid, Manel; Rzaigui, Mohamed; Marouani, Houda

    2016-08-01

    A novel organic-inorganic hybrid compound, trans-2,5-dimethylpiperazine-1,4-diium pentachlorobismuthate(III), [C6H16N2]BiCl5, was synthesized and its structure determined by means of single crystal X-ray diffraction studies. It crystallizes in the monoclinic space group C2/c, with the following parameters: a = 15.365(5), b = 12.634(3), c = 8.313(3) Å, β = 120.59(3)°, Z = 4 and V = 1389.1(7) Å3. Its crystal structure consists of [BiCl5]2- anions surrounded by [C6H16N2]2+ cations. Complex hydrogen bonding interactions between [BiCl5]2- and organic cations through N(C)-H … Cl hydrogen bonds to form a three-dimensional network. The crystal packing is stabilized by Cl … Cl interactions. The structure reveals that the piperazine ring is in a chair conformation. The vibrational spectrum has been measured at room temperature by FT-infrared spectroscopy (4000-400 cm-1) on polycrystalline samples. The number of the NMR components in the 13C CP-MAS NMR spectrum proves the presence of three crystallographically independent carbons as revealed by X-ray structure determination. Investigation of antioxidant activity of compound was carried out by 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical, Ferric Reducing Power (FRP) and Ferrous ion chelating (FIC) methods. The synthesized compound exhibited significant antioxidant activities.

  8. New insights into the comprehension of the magnetic properties of dinuclear Mn(III) compounds with the general formula [{MnL(NN)}2(μ-O)(μ-n-RC6H4COO)2]X2.

    PubMed

    Escriche-Tur, Luis; Font-Bardia, Mercè; Albela, Belén; Corbella, Montserrat

    2016-07-19

    Five new dinuclear Mn(iii) compounds with benzoato derivative bridges [{Mn(bpy)L}2(μ-O)(μ-n-RC6H4COO)2]X2 (n-R = 3-MeO, 4-MeO and 4-tBu, X = NO3(-) and ClO4(-)) were synthesised and characterised. According to X-ray diffraction, the X anions tend to be coordinated to the Mn ions and may occupy the place of the monodentate ligand L. Two structural isomers that only differ in one of their monodentate ligands have been obtained with the 3-MeOC6H4COO(-) bridges. For all compounds, the Mn(iii) ions display elongated octahedra with a pronounced rhombic distortion. To quantify these distortions separately, the elongation and rhombicity parameters Δ and ρ have been defined. The magnetic study shows a good relationship between the distortion of the coordination polyhedra and the zero field splitting parameters (DMn and EMn). From the magnetic data of a powder sample, it is possible to determine the sign and magnitude of DMn for ferromagnetic systems or weak antiferromagnetic systems with DMn < 0. For this kind of dinuclear compound, the R group at the meta position, the rhombic distortion of the octahedra, and large torsion angles between the Jahn-Teller axes lead to ferromagnetic interactions.

  9. Theoretical and experimental investigation on the stability of Cn=1-6H- and Cn=1-4Hx+ clusters

    NASA Astrophysics Data System (ADS)

    Fantuzzi, Felipe; Baptista, Leonardo; Rocha, Alexandre B.; da Silveira, E. F.

    2013-01-01

    A theoretical study on the molecular structure of CnH- clusters, where 1 ⩽ n ⩽ 6, and CnHx+ clusters, where 1 ⩽ n ⩽ 4 and 0 ⩽ x ⩽ 2n + 2, has been performed at the DFT level. More than 300 configurations were examined and their total electronic energies ordered for each cluster mass. The D-plot methodology was employed for classifying different structures into cluster families and identifying the most stable structures. For each family, the binding energies of the analyzed cluster species have been determined and displayed as a function of the cluster mass. The fluctuations of these curves are then compared to experimental data, namely, to the dependence of relative ion desorption yields on cluster mass, obtained from Plasma Desorption Mass Spectroscopy (PDMS) of quite distinct types of organic samples: solid methane, cholesterol and pump oil vapor adsorbed on polycrystalline LiF. It is found that theoretical predictions and experimental data are in good agreement, showing that the abundance of the emitted small cluster ions is determined by their own structure and not by the structure of the original sample.

  10. Periodic density functional theory investigation of the uranyl ion sorption on three mineral surfaces: a comparative study.

    PubMed

    Roques, Jérôme; Veilly, Edouard; Simoni, Eric

    2009-06-04

    Canister integrity and radionuclides retention is of prime importance for assessing the long term safety of nuclear waste stored in engineered geologic depositories. A comparative investigation of the interaction of uranyl ion with three different mineral surfaces has thus been undertaken in order to point out the influence of surface composition on the adsorption mechanism(s). Periodic DFT calculations using plane waves basis sets with the GGA formalism were performed on the TiO(2)(110), Al(OH)(3)(001) and Ni(111) surfaces. This study has clearly shown that three parameters play an important role in the uranyl adsorption mechanism: the solvent (H(2)O) distribution at the interface, the nature of the adsorption site and finally, the surface atoms' protonation state.

  11. Numerical study of the tight-binding approach to overdamped Brownian motion on a tilted periodic potential

    NASA Astrophysics Data System (ADS)

    Challis, K. J.

    2016-12-01

    We present a numerical study of the tight-binding approach to overdamped Brownian motion on a tilted periodic potential. In the tight-binding method the probability density is expanded on a basis of Wannier states to transform the Smoluchowski equation to a discrete master equation that can be interpreted in terms of thermal hopping between potential minima. We calculate the Wannier states and hopping rates for a variety of potentials, including tilted cosine and ratchet potentials. For deep potential minima the Wannier states are well localized and the hopping rates between nearest-neighbor states are qualitatively well described by Kramers' escape rate. The next-nearest-neighbor hopping rates are negative and must be negligible compared to the nearest-neighbor rates for the discrete master equation treatment to be valid. We find that the validity of the master equation extends beyond the quantitative applicability of Kramers' escape rate.

  12. Deep Long-period Seismicity Beneath the Executive Committee Range, Marie Byrd Land, Antarctica, Studied Using Subspace Detection

    NASA Astrophysics Data System (ADS)

    Aster, R. C.; McMahon, N. D.; Myers, E. K.; Lough, A. C.

    2015-12-01

    Lough et al. (2014) first detected deep sub-icecap magmatic events beneath the Executive Committee Range volcanoes of Marie Byrd Land. Here, we extend the identification and analysis of these events in space and time utilizing subspace detection. Subspace detectors provide a highly effective methodology for studying events within seismic swarms that have similar moment tensor and Green's function characteristics and are particularly effective for identifying low signal-to-noise events. Marie Byrd Land (MBL) is an extremely remote continental region that is nearly completely covered by the West Antarctic Ice Sheet (WAIS). The southern extent of Marie Byrd Land lies within the West Antarctic Rift System (WARS), which includes the volcanic Executive Committee Range (ECR). The ECR shows north-to-south progression of volcanism across the WARS during the Holocene. In 2013, the POLENET/ANET seismic data identified two swarms of seismic activity in 2010 and 2011. These events have been interpreted as deep, long-period (DLP) earthquakes based on depth (25-40 km) and low frequency content. The DLP events in MBL lie beneath an inferred sub-WAIS volcanic edifice imaged with ice penetrating radar and have been interpreted as a present location of magmatic intrusion. The magmatic swarm activity in MBL provides a promising target for advanced subspace detection and temporal, spatial, and event size analysis of an extensive deep long period earthquake swarm using a remote seismographic network. We utilized a catalog of 1,370 traditionally identified DLP events to construct subspace detectors for the six nearest stations and analyzed two years of data spanning 2010-2011. Association of these detections into events resulted in an approximate ten-fold increase in number of locatable earthquakes. In addition to the two previously identified swarms during early 2010 and early 2011, we find sustained activity throughout the two years of study that includes several previously

  13. Effect of red chili consumption on postoperative symptoms during the post-hemorrhoidectomy period: randomized, double-blind, controlled study.

    PubMed

    Gupta, Pravin J

    2007-09-01

    The aim of this study was to determine whether there was any relation between consumption of chilies and postoperative symptoms after hemorrhoidectomy in patients with grade III or IV hemorrhoidal disease. A total of 60 patients were randomly assigned to receive antibiotics and analgesics alone (control patients) or daily consumption of 3 g of chili powder along with identical antibiotics and analgesics (chili group). The evaluation of symptoms-pain, anal burning, pruritus, bleeding-during the postoperative period was assessed by means of patients' self-questionnaires. A global score for evaluating each postoperative symptom was compared between the two groups at the 1-week follow-up. No significant difference in age, sex distribution, or grade of disease was noted between the two groups at baseline. The incidence of post-hemorrhoidectomy symptoms was higher in the group consuming chilies during the first postoperative week. The global score for postoperative pain (14.60 for the chili group vs. 7.97 for the control group, p < 0.001) and for anal burning (12.90 for the chili group vs. 7.82 for the control group, p < 0.0001) were significant. Although bleeding (6.95 in the control group and 7.57 in the chili group, p < 0.81) and pruritus (8.06 in the control group and 8.75 in the chili group, p < 0.69) were more common in the chili group, the difference did not achieve statistical significance. This study shows that consumption of 3 g of red chilies per day during the postoperative period after hemorrhoidectomy increases the intensity of typical postoperative symptoms, stool frequency, and the consumption of analgesics.

  14. Geographic variability of fatal road traffic injuries in Spain during the period 2002–2004: an ecological study

    PubMed Central

    Rivas-Ruiz, Francisco; Perea-Milla, Emilio; Jimenez-Puente, Alberto

    2007-01-01

    Background The aim of the present study is to describe the inter-province variability of Road Traffic Injury (RTI) mortality on Spanish roads, adjusted for vehicle-kilometres travelled, and to assess the possible role played by the following explicative variables: sociodemographic, structural, climatic and risk conducts. Methods An ecological study design was employed. The mean annual rate of RTI deaths was calculated for the period 2002–2004, adjusted for vehicle-kilometres travelled, in the 50 provinces of Spain. The RTI death rate was related with the independent variables described above, using simple and multiple linear regression analysis with backward step-wise elimination. The level of statistical significance was taken as p < 0.05. Results In the period 2002–2004 there were 12,756 RTI deaths in Spain (an average of 4,242 per year, SD = 356.6). The mean number of deaths due to RTI per 100 million vehicle-kilometres (mvk) travelled was 1.76 (SD = 0.51), with a minimum value of 0.66 (in Santa Cruz de Tenerife) and a maximum of 3.31 (in the province of Lugo). All other variables being equal, a higher proportion of kilometres available on high capacity roads, and a higher cultural and education level were associated with lower death rates due to RTI, while the opposite was true for the rate of alcohol consumers and the road traffic volume of heavy vehicles. The variables included in the model accounted for 55.4% of the variability in RTI mortality. Conclusion Adjusting RTI mortality rates for the number of vehicle-kilometres travelled enables us to identify the high variability of this cause of death, and its relation with risk factors other than those inherent to human behaviour, such as the type of roads and the type of vehicles using them. PMID:17897449

  15. A clinical study of kuru patients with long incubation periods at the end of the epidemic in Papua New Guinea

    PubMed Central

    Collinge, John; Whitfield, Jerome; McKintosh, Edward; Frosh, Adam; Mead, Simon; Hill, Andrew F.; Brandner, Sebastian; Thomas, Dafydd; Alpers, Michael P.

    2008-01-01

    Kuru is so far the principal human epidemic prion disease. While its incidence has steadily declined since the cessation of its route of transmission, endocannibalism, in Papua New Guinea in the 1950s, the arrival of variant Creutzfeldt–Jakob disease (vCJD), also thought to be transmitted by dietary prion exposure, has given kuru a new global relevance. We investigated all suspected cases of kuru from July 1996 to June 2004 and identified 11 kuru patients. There were four females and seven males, with an age range of 46–63 years at the onset of disease, in marked contrast to the age and sex distribution when kuru was first investigated 50 years ago. We obtained detailed histories of residence and exposure to mortuary feasts and performed serial neurological examination and genetic studies where possible. All patients were born a significant period before the mortuary practice of transumption ceased and their estimated incubation periods in some cases exceeded 50 years. The principal clinical features of kuru in the studied patients showed the same progressive cerebellar syndrome that had been previously described. Two patients showed marked cognitive impairment well before preterminal stages, in contrast to earlier clinical descriptions. In these patients, the mean clinical duration of 17 months was longer than the overall average in kuru but similar to that previously reported for the same age group, and this may relate to the effects of both patient age and PRNP codon 129 genotype. Importantly, no evidence for lymphoreticular colonization with prions, seen uniformly in vCJD, was observed in a patient with kuru at tonsil biopsy. PMID:18849289

  16. Study of cosmic ray intensity and geomagnetic storms with solar wind parameters during the period 1998-2005

    NASA Astrophysics Data System (ADS)

    Kharayat, Hema; Prasad, Lalan

    2017-01-01

    The aim of this paper is to study the effect of solar wind parameters (solar wind speed V, plasma flow pressure, and plasma density) on cosmic ray intensity and on geomagnetic storms for the period 1998-2005 (solar cycle 23). A Chree analysis by the superposed epoch method has been done for the study. From the present study we have found that the solar wind speed is a highly effective parameter in producing cosmic ray intensity decreases and geomagnetic storms. No time lag is found between cosmic ray intensity decreases, geomagnetic storms, and peak value of solar wind speed. Further, we have found that the plasma flow pressure is effectively correlated with geomagnetic storms but it is weakly correlated with cosmic ray intensity. The cosmic ray intensity and geomagnetic storms are found to be weakly correlated with plasma density. The decrease in cosmic ray intensity and geomagnetic storms takes place one day after the peak values of plasma flow pressure and plasma density. There is a time lag of one day between solar wind parameters (plasma flow pressure and plasma density) and cosmic ray intensity decrease, geomagnetic storms. Also, we have found a high correlation of cosmic ray intensity and geomagnetic storms with the product of interplanetary magnetic field B and solar wind speed V i.e. B\\cdot V. This study may be useful in predicting the space-weather phenomena.

  17. Eating Disorders, Pregnancy, and the Postpartum Period: Findings from the Norwegian Mother and Child Cohort Study (MoBa).

    PubMed

    Watson, Hunna J; Torgersen, Leila; Zerwas, Stephanie; Reichborn-Kjennerud, Ted; Knoph, Cecilie; Stoltenberg, Camilla; Siega-Riz, Anna Maria; Von Holle, Ann; Hamer, Robert M; Meltzer, Helle; Ferguson, Elizabeth H; Haugen, Margaretha; Magnus, Per; Kuhns, Rebecca; Bulik, Cynthia M

    2014-01-01

    This review summarizes studies on eating disorders in pregnancy and the postpartum period that have been conducted as part of the broader Norwegian Mother and Child Cohort Study (MoBa). Prior to the 2000s, empirical literature on eating disorders in pregnancy was sparse and consisted mostly of studies in small clinical samples. MoBa has contributed to a new era of research by making population-based and large-sample research possible. To date, MoBa has led to 19 studies on diverse questions including the prevalence, course, and risk correlates of eating disorders during pregnancy and the postpartum. The associations between eating disorder exposure and pregnancy, birth and obstetric outcomes, and maternal and offspring health and well-being, have also been areas of focus. The findings indicate that eating disorders in pregnancy are relatively common and appear to confer health risks to mother and her child related to sleep, birth outcomes, maternal nutrition, and child feeding and eating.

  18. Eating Disorders, Pregnancy, and the Postpartum Period: Findings from the Norwegian Mother and Child Cohort Study (MoBa)

    PubMed Central

    Watson, Hunna J.; Torgersen, Leila; Zerwas, Stephanie; Reichborn-Kjennerud, Ted; Knoph, Cecilie; Stoltenberg, Camilla; Siega-Riz, Anna Maria; Von Holle, Ann; Hamer, Robert M.; Meltzer, Helle; Ferguson, Elizabeth H.; Haugen, Margaretha; Magnus, Per; Kuhns, Rebecca; Bulik, Cynthia M.

    2016-01-01

    This review summarizes studies on eating disorders in pregnancy and the postpartum period that have been conducted as part of the broader Norwegian Mother and Child Cohort Study (MoBa). Prior to the 2000s, empirical literature on eating disorders in pregnancy was sparse and consisted mostly of studies in small clinical samples. MoBa has contributed to a new era of research by making population-based and large-sample research possible. To date, MoBa has led to 19 studies on diverse questions including the prevalence, course, and risk correlates of eating disorders during pregnancy and the postpartum. The associations between eating disorder exposure and pregnancy, birth and obstetric outcomes, and maternal and offspring health and well-being, have also been areas of focus. The findings indicate that eating disorders in pregnancy are relatively common and appear to confer health risks to mother and her child related to sleep, birth outcomes, maternal nutrition, and child feeding and eating. PMID:27110061

  19. Clinical learning environments for student nurses: key indices from two studies compared over a 25 year period.

    PubMed

    Lewin, David

    2007-07-01

    In 1978, a longitudinal study commenced in England to illuminate criteria for the evaluation of hospital wards as clinical learning environments for student nurses. It derived measures to quantify the clinical learning experienced by 71 students in three cohorts in three training hospitals over their entire programme. In 2003, a second study, based in one English School of Health Studies, using clinical placements in three NHS trusts, employed a retrospective, cross-sectional, analytic survey design with anonymised, self-completion questionnaires, to map the clinical learning of 272 students as part of a quality assurance and enhancement initiative. This paper explores changes over time by comparing data based on five key indices, devised in the first study and revisited in the second. Concepts of clinical learning and supervision are reviewed as part of this changing context and background together with limitations implicit in the comparison. The findings suggest an average 20% improvement in the quality of hospital based clinical learning environments over a 25 year period, based mainly on trained staff personally supervising students more extensively, testing their theoretical knowledge more frequently and spending more time performing practical procedures with them. However, unacceptable variations in clinical learning opportunities persist for some students.

  20. Experimental demonstration of mode-selective phonon excitation of 6H-SiC by a mid-infrared laser with anti-Stokes Raman scattering spectroscopy

    SciTech Connect

    Yoshida, Kyohei; Hachiya, Kan; Okumura, Kensuke; Mishima, Kenta; Inukai, Motoharu; Torgasin, Konstantin; Omer, Mohamed; Sonobe, Taro; Zen, Heishun; Negm, Hani; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki

    2013-10-28

    Mode-selective phonon excitation by a mid-infrared laser (MIR-FEL) is demonstrated via anti-Stokes Raman scattering measurements of 6H-silicon carbide (SiC). Irradiation of SiC with MIR-FEL and a Nd-YAG laser at 14 K produced a peak where the Raman shift corresponds to a photon energy of 119 meV (10.4 μm). This phenomenon is induced by mode-selective phonon excitation through the irradiation of MIR-FEL, whose photon energy corresponds to the photon-absorption of a particular phonon mode.

  1. Copper, Silver and Sodium Salt-Mediated Quaternization by Arylation: Syntheses of N-Heterocyclic Carbene Precursors and 6-H-Phenanthridine Derivatives.

    PubMed

    Shen, Wenqi; Li, Jing; Zhang, Caiyun; Shi, Min; Zhang, Jun

    2016-07-05

    We have developed a Cu(II) -, Ag(I) -, and NaOTf-mediated intramolecular quaternization by arylation reactions to synthesize a variety of N-heterocyclic carbene (NHC) precursors with a benzene-fused backbone. The methodology also provides a convenient alternative route for the synthesis of 6-H-phenanthridine derivatives. A novel silver-NHC complex was prepared by treatment of Ag2 O with the free carbene, which was in situ prepared from the deprotonation of a representative quinazolinonium salt.

  2. The ionothermal synthesis of metal organic frameworks, Ln(C 9O 6H 3)((CH 3NH) 2CO) 2, using deep eutectic solvents

    NASA Astrophysics Data System (ADS)

    Himeur, Farida; Stein, Irene; Wragg, David S.; Slawin, Alexandra M. Z.; Lightfoot, Philip; Morris, Russell E.

    2010-04-01

    Three new isostructural materials Ln(TMA)(DMU) 2 (Ln(C 9O 6H 3)((CH 3NH) 2CO) 2; Ln: La 1, Nd 2, Eu 3; TMA: trimesate, DMU: dimethylurea) have been synthesised ionothermally using a choline chloride/dimethylurea deep eutectic mixture as the solvent. Normally in ionothermal synthesis the urea portion of the deep eutectic solvent is unstable, breaking down to release ammonium cations that act as templates. In the case of 1- 3, however, the dimethylurea remains intact and is incorporated into the final structure.

  3. Volumetric Properties of the Mixture Trichloroethene C2HCl3 + C6H14O Hexan-1-ol (VMSD1511, LB4852_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Trichloroethene C2HCl3 + C6H14O Hexan-1-ol (VMSD1511, LB4852_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  4. Volumetric Properties of the Mixture Ethyl ethanoate C4H8O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1412, LB4314_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Ethyl ethanoate C4H8O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1412, LB4314_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  5. Volumetric Properties of the Mixture 2-Methoxyethanol C3H8O2 + C6H12O2 Butyl ethanoate (VMSD1412, LB4311_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2-Methoxyethanol C3H8O2 + C6H12O2 Butyl ethanoate (VMSD1412, LB4311_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  6. Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C10H22O Decan-1-ol (VMSD1412, LB3877_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C10H22O Decan-1-ol (VMSD1412, LB3877_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  7. Volumetric Properties of the Mixture Ethanol C2H6O + C6H14Hexane (VMSD1412, LB3181_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Ethanol C2H6O + C6H14 Hexane (VMSD1412, LB3181_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  8. Volumetric Properties of the Mixture 2-Methoxyethanol C3H8O2 + C6H12O2 Butyl ethanoate (VMSD1511, LB4134_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2-Methoxyethanol C3H8O2 + C6H12O2 Butyl ethanoate (VMSD1511, LB4134_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  9. Volumetric Properties of the Mixture Trichloromethane CHCl3 + C6H14O Hexan-1-ol (VMSD1412, LB5058_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Trichloromethane CHCl3 + C6H14O Hexan-1-ol (VMSD1412, LB5058_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  10. Volumetric Properties of the Mixture 1,3-Dioxane C4H8O2 + C6H12 Cyclohexane (VMSD1511, LB5121_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 1,3-Dioxane C4H8O2 + C6H12 Cyclohexane (VMSD1511, LB5121_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  11. Volumetric Properties of the Mixture Ethanol C2H6O + C6H14 Hexane (VMSD1511, LB3179_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Ethanol C2H6O + C6H14 Hexane (VMSD1511, LB3179_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  12. Volumetric Properties of the Mixture Cyclohexanol C6H12O + C7H14O Cycloheptanol (VMSD1511, LB4375_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Cyclohexanol C6H12O + C7H14O Cycloheptanol (VMSD1511, LB4375_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  13. Volumetric Properties of the Mixture Trichloroethene C2HCl3 + C6H14O Hexan-1-ol (VMSD1412, LB4858_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Trichloroethene C2HCl3 + C6H14O Hexan-1-ol (VMSD1412, LB4858_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  14. Volumetric Properties of the Mixture 2-Ethoxyethanol C4H10O2 + C6H12O2 Butyl ethanoate (VMSD1511, LB4136_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2-Ethoxyethanol C4H10O2 + C6H12O2 Butyl ethanoate (VMSD1511, LB4136_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  15. Volumetric Properties of the Mixture 2-Ethoxyethanol C4H10O2 + C6H12O2 Butyl ethanoate (VMSD1412, LB4313_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2-Ethoxyethanol C4H10O2 + C6H12O2 Butyl ethanoate (VMSD1412, LB4313_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  16. Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C10H22O Decan-1-ol (VMSD1511, LB3561_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 2,2-Dimethylbutane C6H14 + C10H22O Decan-1-ol (VMSD1511, LB3561_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  17. Volumetric Properties of the Mixture Ethyl ethanoate C4H8O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1511, LB4137_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Ethyl ethanoate C4H8O2 + C6H14O2 3-Oxaheptan-1-ol (VMSD1511, LB4137_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).

  18. Volumetric Properties of the Mixture Cyclohexanol C6H12O + C7H14O Cycloheptanol (VMSD1412, LB4377_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Cyclohexanol C6H12O + C7H14O Cycloheptanol (VMSD1412, LB4377_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  19. Volumetric Properties of the Mixture Benzene C6H6 + C7H8O Methyl phenyl ether (VMSD1412, LB4561_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Benzene C6H6 + C7H8O Methyl phenyl ether (VMSD1412, LB4561_V)' providing data by calculation of isentropic compressibility from low-pressure density and thermodynamic speed of sound data at variable mole fraction and constant temperature, in the single-phase region(s).

  20. Volumetric Properties of the Mixture Trichloromethane CHCl3 + C6H14O Hexan-1-ol (VMSD1511, LB5055_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Trichloromethane CHCl3 + C6H14O Hexan-1-ol (VMSD1511, LB5055_V)' providing data from direct measurement of low-pressure thermodynamic speed of sound at variable mole fraction and constant temperature, in the single-phase region(s).