WorldWideScience

Sample records for acetylene intersystem crossing

  1. Interference in acetylene intersystem crossing acts as the molecular analog of Young's double-slit experiment

    NARCIS (Netherlands)

    M. de Groot; R.W. Field; W.J. Buma

    2009-01-01

    We report on an experimental approach that reveals crucial details of the composition of singlet-triplet mixed eigenstates in acetylene. Intersystem crossing in this prototypical polyatomic molecule embodies the mixing of the lowest excited singlet state (S1) with 3 triplet states (T1, T2, and T3).

  2. Internal Conversion vs. Intersystem Crossing – What Drives the Dynamics of Cyclic α,β-Enones?

    Directory of Open Access Journals (Sweden)

    Riedle E.

    2013-03-01

    Full Text Available The origin of ultrafast intersystem crossing and its competitiveness with singlet pathways was studied in cyclic α,β-enones by transient absorption, time-resolved photoelectron spectroscopy and ab initio calculations.

  3. The DNA Nucleobase Thymine in Motion - Intersystem Crossing Simulated with Surface Hopping

    CERN Document Server

    Mai, Sebastian; Marquetand, Philipp; González, Leticia

    2016-01-01

    We report ab initio excited-state dynamics simulations on isolated thymine to investigate the mechanism of intersystem crossing, based on CASSCF potential energy surfaces and the \\textsc{Sharc} surface hopping method. We show that even though $S_2 \\rightarrow S_1$ internal conversion is not described accurately with CASSCF, intersystem crossing can be correctly simulated. Intersystem crossing in thymine occurs from the $S_1$ ($^1n\\pi^*$) minimum, via a nearby crossing with $T_2$ ($^3\\pi\\pi^*$). The system further relaxes via ultrafast internal conversion in the triplet manifold to the $T_1$ ($^3\\pi\\pi^*$) state. The simulations reveal that, once the system is trapped in the $^1n\\pi^*$ minimum, intersystem crossing might proceed with a time constant of 1~ps. Furthermore, the change of the system's electronic state is accompanied respectively by elongation/shortening of specific bonds, which could thus be used as indicators to identify which state is populated in the dynamics.

  4. Single-molecule fluorescence autocorrelation experiments on pentacene : The dependence of intersystem crossing on isotopic composition

    NARCIS (Netherlands)

    Brouwer, A.C.J.; Köhler, J.; Oijen, A.M. van; Groenen, E.J.J.; Schmidt, J.

    1999-01-01

    Single pentacene molecules containing 13C or 1H in a pentacene-d14 doped p-terphenyl crystal have been studied by fluorescence autocorrelation. The triplet dynamics has been analyzed and a systematic dependence of the S1→T1 intersystem crossing rate on isotopic composition was found. This variation

  5. Nonadiabatic dynamics with intersystem crossings: A time-dependent density functional theory implementation

    Energy Technology Data Exchange (ETDEWEB)

    Franco de Carvalho, F. [Centre Européen de Calcul Atomique et Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Tavernelli, I. [IBM Research GmbH, Zurich Research Laboratory, 8803 Ruschlikon (Switzerland)

    2015-12-14

    In this work, we derive a method to perform trajectory-based nonadiabatic dynamics that is able to describe both nonadiabatic transitions and intersystem crossing events (transitions between states of different spin-multiplicity) at the same level of theory, namely, time-dependent density functional theory (TDDFT). To this end, we combined our previously developed TDDFT-based trajectory surface hopping scheme with an accurate and efficient algorithm for the calculation of the spin-orbit coupling (SOC) matrix elements. More specifically, we designed two algorithms for the calculation of intersystem crossing transitions, one based on an extended Tully’s surface hopping scheme including SOC and the second based on a Landau-Zener approximation applied to the spin sector of the electronic Hilbert space. This development allows for the design of an efficient on-the-fly nonadiabatic approach that can handle, on an equal footing, nonadiabatic and intersystem crossing transitions. The method is applied to the study of the photophysics of sulfur dioxide (SO{sub 2}) in gas and liquid phases.

  6. Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

    Science.gov (United States)

    Curchod, Basile F. E.; Rauer, Clemens; Marquetand, Philipp; González, Leticia; Martínez, Todd J.

    2016-03-01

    Full multiple spawning is a formally exact method to describe the excited-state dynamics of molecular systems beyond the Born-Oppenheimer approximation. However, it has been limited until now to the description of radiationless transitions taking place between electronic states with the same spin multiplicity. This Communication presents a generalization of the full and ab initio multiple spawning methods to both internal conversion (mediated by nonadiabatic coupling terms) and intersystem crossing events (triggered by spin-orbit coupling matrix elements) based on a spin-diabatic representation. The results of two numerical applications, a model system and the deactivation of thioformaldehyde, validate the presented formalism and its implementation.

  7. The role of Duschinsky rotation in intersystem crossing: A case study of uracil

    Directory of Open Access Journals (Sweden)

    Etinski Mihajlo

    2011-01-01

    Full Text Available The intersystem crossing rate for the transition between the lowest excited singlet and triplet electronic states of uracil was studied by means of ab initio methods. The rate was evaluated using the timedependent approach based on the correlation function and its two approximations: the second-order cumulant expansion and the short-time approximation. The normal modes of the singlet and triplet states are related by the Duschinsky transformation, i.e., by rotation and translation. It was found that for singlet-triplet adiabatic energy gaps below 6000 cm-1, the inclusion of the Duschinsky rotation is necessary for quantitative results. Above energy gaps of 6000 cm-1, the rates obtained with and without the Duschinsky rotation are similar. The cumulant expansion approximates well the correlation function. The short-time approximation, although crude, can be used as the first estimate of the rate.

  8. Direct observation of slow intersystem crossing in an aromatic ketone, fluorenone.

    Science.gov (United States)

    Soep, Benoît; Mestdagh, Jean-Michel; Briant, Marc; Gaveau, Marc-André; Poisson, Lionel

    2016-08-17

    Direct measurements of Single vibronic Level InterSystem Crossing (SLISC) have been performed on the fluorenone molecule in the gas phase, by time resolved photoelectron and photoion spectroscopy. Vibronic transitions above the S1 nπ* origin were excited in the 432-420 nm region and the decay of S1 and growth of T1(3)ππ* could be observed within a 10 ns time domain. The ionization potential is measured as 8.33 ± 0.04 eV. The energy of the first excited triplet state of fluorenone, T1 has been characterized directly at 18 640 ± 250 cm(-1). The internal conversion of S1 to S0 is found to amount to ∼15% of the population decay, thus ISC is the dominant electronic relaxation process. ISC, although favored by the S1(1)nπ*-T1(3)ππ* coupling scheme, is 3 orders of magnitude less efficient than in the similar molecule benzophenone. Thus, the planarity of the fluorenone molecule disfavors the exploration of the configuration space where surface crossings would create high ISC probability, which occurs in benzophenone through surface crossings. The time evolution of S1 fluorenone is well accounted for by the statistical decay of individual levels into a quasi-continuum of T1 vibronic levels. PMID:27485671

  9. Fluorescence via Reverse Intersystem Crossing from Higher Triplet States in a Bisanthracene Derivative

    CERN Document Server

    Sato, Tohru; Haruta, Naoki; Pu, Yong-Jin

    2016-01-01

    To elucidate the high external quantum efficiency observed for organic light-emitting diodes using a bisanthracene derivative, BD1, as the emitting molecule, off-diagonal vibronic coupling constants (VCCs) between the excited states of BD1, which govern non-radiative transition rates, were calculated employing time-dependent density functional theory. The VCCs were analysed based on the concept of vibronic coupling density. The VCC calculations suggest a fluorescence via higher triplets (FvHT) mechanism, which entails the conversion of a T$_4$ exciton generated during electrical excitation into an S$_2$ exciton via reverse intersystem crossing (RISC); moreover, the S$_2$ exciton relaxes to a fluorescent S$_1$ exciton because of large vibronic coupling between S$_2$ and S$_1$. This mechanism is valid as long as the relaxation of triplet states higher than T$_1$ to lower states is suppressed. The symmetry-controlled thermally activated delayed fluorescence (SC-TADF) and inverted singlet and triplet (iST) struct...

  10. Intersystem crossing rates of S1 state keto-amino cytosine at low excess energy

    Science.gov (United States)

    Lobsiger, Simon; Etinski, Mihajlo; Blaser, Susan; Frey, Hans-Martin; Marian, Christel; Leutwyler, Samuel

    2015-12-01

    The amino-keto tautomer of supersonic jet-cooled cytosine undergoes intersystem crossing (ISC) from the v = 0 and low-lying vibronic levels of its S1(1ππ∗) state. We investigate these ISC rates experimentally and theoretically as a function of S1 state vibrational excess energy Eexc. The S1 vibronic levels are pumped with a ˜5 ns UV laser, the S1 and triplet state ion signals are separated by prompt or delayed ionization with a second UV laser pulse. After correcting the raw ISC yields for the relative S1 and T1 ionization cross sections, we obtain energy dependent ISC quantum yields QISC corr = 1 % -5%. These are combined with previously measured vibronic state-specific decay rates, giving ISC rates kISC = 0.4-1.5 ṡ 109 s-1, the corresponding S1⇝S0 internal conversion (IC) rates are 30-100 times larger. Theoretical ISC rates are computed using SCS-CC2 methods, which predict rapid ISC from the S1; v = 0 state with kISC = 3 ṡ 109 s-1 to the T1(3ππ∗) triplet state. The surprisingly high rate of this El Sayed-forbidden transition is caused by a substantial admixture of 1nOπ∗ character into the S1(1ππ∗) wave function at its non-planar minimum geometry. The combination of experiment and theory implies that (1) below Eexc = 550 cm-1 in the S1 state, S1⇝S0 internal conversion dominates the nonradiative decay with kIC ≥ 2 ṡ 1010 s-1, (2) the calculated S1⇝T1 (1ππ∗⇝3ππ∗) ISC rate is in good agreement with experiment, (3) being El-Sayed forbidden, the S1⇝T1 ISC is moderately fast (kISC = 3 ṡ 109 s-1), and not ultrafast, as claimed by other calculations, and (4) at Eexc ˜ 550 cm-1 the IC rate increases by ˜50 times, probably by accessing the lowest conical intersection (the C5-twist CI) and thereby effectively switching off the ISC decay channels.

  11. Spin-orbit Coupling and Intersystem Crossing in 4H-Pyran-4-thione: CASSCF//TD-B3LYP Study

    Institute of Scientific and Technical Information of China (English)

    L(U), Ling-Ling; LIU, Xin-Wen; YUAN, Kun; WANG, Yong-Cheng; WANG, Han-Qing

    2007-01-01

    The intersystem crossing channels of gaseous 4H-pyran-4-thione were investigated using the CASSCF//TD-B3LYP methods and group theory. Using the effective one-electron spin-orbit Hamiltonian, the strengths of spin-orbit coupling were estimated, which plays an essential role in the spin transitions between different spin states. Calculated results show that phosphorescence and non-radiative decay via intersystem crossing to the S0 state are concurrent processes occurring at the T1 state. A rapid depletion of the S1 state via intersystem crossing to the T1 state can be mediated by the T2 state, if spin relaxation is fast within the triplet levels. Our calculated results are in close agreement with experimental observations.

  12. Ab Initio Multiple Spawning Method for Intersystem Crossing Dynamics: Spin-Forbidden Transitions between (3)B1 and (1)A1 States of GeH2.

    Science.gov (United States)

    Fedorov, Dmitry A; Pruitt, Spencer R; Keipert, Kristopher; Gordon, Mark S; Varganov, Sergey A

    2016-05-12

    Dynamics at intersystem crossings are fundamental to many processes in chemistry, physics, and biology. The ab initio multiple spawning (AIMS) method was originally developed to describe internal conversion dynamics at conical intersections where derivative coupling is responsible for nonadiabatic transitions between electronic states with the same spin multiplicity. Here, the applicability of the AIMS method is extended to intersystem crossing dynamics in which transitions between electronic states with different spin multiplicities are mediated by relativistic spin-orbit coupling. In the direct AIMS dynamics, the nuclear wave function is expanded in the basis of frozen multidimensional Gaussians propagating on the coupled electronic potential energy surfaces calculated on the fly. The AIMS method for intersystem crossing is used to describe the nonadiabatic transitions between the (3)B1 and (1)A1 states of GeH2. The potential energies and gradients were obtained at the CASSCF(6,6)/6-31G(d) level of theory. The spin-orbit coupling matrix elements were calculated with the configuration interaction method using the two-electron Breit-Pauli Hamiltonian. The excited (3)B1 state lifetime and intersystem crossing rate constants were estimated by fitting the AIMS state population with the first-order kinetics equation for a reversible unimolecular reaction. The obtained rate constants are compared with the values predicted by the statistical nonadiabatic transition state theory with transition probabilities calculated using the Landau-Zener and weak coupling formulas. PMID:27064356

  13. Ab Initio Multiple Spawning Method for Intersystem Crossing Dynamics: Spin-Forbidden Transitions between (3)B1 and (1)A1 States of GeH2.

    Science.gov (United States)

    Fedorov, Dmitry A; Pruitt, Spencer R; Keipert, Kristopher; Gordon, Mark S; Varganov, Sergey A

    2016-05-12

    Dynamics at intersystem crossings are fundamental to many processes in chemistry, physics, and biology. The ab initio multiple spawning (AIMS) method was originally developed to describe internal conversion dynamics at conical intersections where derivative coupling is responsible for nonadiabatic transitions between electronic states with the same spin multiplicity. Here, the applicability of the AIMS method is extended to intersystem crossing dynamics in which transitions between electronic states with different spin multiplicities are mediated by relativistic spin-orbit coupling. In the direct AIMS dynamics, the nuclear wave function is expanded in the basis of frozen multidimensional Gaussians propagating on the coupled electronic potential energy surfaces calculated on the fly. The AIMS method for intersystem crossing is used to describe the nonadiabatic transitions between the (3)B1 and (1)A1 states of GeH2. The potential energies and gradients were obtained at the CASSCF(6,6)/6-31G(d) level of theory. The spin-orbit coupling matrix elements were calculated with the configuration interaction method using the two-electron Breit-Pauli Hamiltonian. The excited (3)B1 state lifetime and intersystem crossing rate constants were estimated by fitting the AIMS state population with the first-order kinetics equation for a reversible unimolecular reaction. The obtained rate constants are compared with the values predicted by the statistical nonadiabatic transition state theory with transition probabilities calculated using the Landau-Zener and weak coupling formulas.

  14. A multi-dimensional microcanonical Monte Carlo study of S_0→T_1 intersystem crossing of isocyanic acid

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; FANG WeiHai; LUO Yi; LIU RuoZhuang

    2009-01-01

    A general formula for the multi-dimensional Monte Carlo microcanonical nonadiabatic rate constant expressed in configuration space is applied to calculate the rate of intersystem crossing (ISC) between the ground (S_0) and first excited triplet (T_1) states for isocyanic acid.One-,two-and three-dimensional potential energy surfaces are constructed by coupled-cluster single-double CCSD calculations,which are used for Monte Carlo sampling.The calculated S_0→T_1 ISC rate is in good agreement with experimental findings,which gives us a reason to believe that the multi-dimensional Monte Carlo microcanonical nonadiabatic rate theory is a very effective method for calculating nonadiabatic transition rate of a polyatomic molecule.

  15. Absolute cross sections for dissociative electron attachment to acetylene and diacetylene

    OpenAIRE

    May, Olivier; Fedor, Juraj; Ibănescu, Bogdan C.; Allan, Michael

    2008-01-01

    Absolute cross sections for the production of the two astronomy-relevant negative ions H−C≡C⁻ and H−C≡C−C≡C⁻ by dissociative electron attachment to acetylene C₂H₂ and diacetylene C₄H₂ were measured (with a ±25% error bar). Acetylene yielded the C₂H⁻ ion at an electron energy of 2.95  eV with a cross section of 3.6±0.9  pm² and also the C₂⁻ ion at 8.1  eV with a cross section of 4.1±1  pm². Diacetylene yielded the C₄H⁻ ion at 2.5  eV with a cross section of 3.0±0.8  pm² and at 5.25  eVwith a c...

  16. Singlet and triplet excited states and intersystem crossing in free-base porphyrin: TDDFT and DFT/MRCI study.

    Science.gov (United States)

    Perun, Serhiy; Tatchen, Jörg; Marian, Christel M

    2008-02-01

    Extensive time-dependent DFT (TDDFT) and DFT/multireference configuration interaction (MRCI) calculations are performed on the singlet and triplet excited states of free-base porphyrin, with emphasis on intersystem crossing processes. The equilibrium geometries, as well as the vertical and adiabatic excitation energies of the lowest singlet and triplet excited states are determined. Single and double proton-transfer reactions in the first excited singlet state are explored. Harmonic vibrational frequencies are calculated at the equilibrium geometries of the ground state and of the lowest singlet and triplet excited states. Furthermore, spin-orbit coupling matrix elements of the lowest singlet and triplet states and their numerical derivatives with respect to nuclear displacements are computed. It is shown that opening of an unprotonated pyrrole ring as well as excited-state single and double proton transfer inside the porphyrin cavity lead to crossings of the potential energy curves of the lowest singlet and triplet excited states. It is also found that displacements along out-of-plane normal modes of the first excited singlet state cause a significant increase of the , , and spin-orbit coupling matrix elements. These phenomena lead to efficient radiationless deactivation of the lowest excited states of free-base porphyrin via intercombination conversion. In particular, the S1-->T1 population transfer is found to proceed at a rate of approximately 10(7) s(-1) in the isolated molecule. PMID:18189251

  17. Quantum confinement-tunable intersystem crossing and the triplet state lifetime of cationic porphyrin–CdTe quantum dot nano-assemblies

    KAUST Repository

    Ahmed, Ghada H.

    2015-03-27

    Here, we report a ground-state interaction between the positively charged cationic porphyrin and the negatively charged carboxylate groups of the thiol ligands on the surface of CdTe quantum dots (QDs), leading to the formation of a stable nanoassembly between the two components. Our time-resolved data clearly demonstrate that we can dramatically tune the intersystem crossing (ISC) and the triplet state lifetime of porphyrin by changing the size of the QDs in the nanoassembly.

  18. Photo-assisted intersystem crossing: The predominant triplet formation mechanism in some isolated polycyclic aromatic molecules excited with pulsed lasers

    International Nuclear Information System (INIS)

    Naphthalene, anthracene, and phenanthrene are shown to have very long-lived triplet lifetimes when the isolated molecules are excited with nanosecond pulsed lasers resonant with the lowest singlet state. For naphthalene, triplet state populations are created only during the laser pulse, excluding the possibility of normal intersystem crossing at the one photon level, and all molecules have triplet lifetimes greater than hundreds of microseconds, similar to the behavior previously reported for phenylacetylene. Although containing 7-12 thousand cm-1 of vibrational energy, the triplet molecules have ionization thresholds appropriate to vibrationless T1 states. The laser power dependences (slopes of log-log power plots) of the excited singlet and triplet populations are about 0.7 for naphthalene and about 0.5 for anthracene. Kinetic modeling of the power dependences successfully reproduces the experimental results and suggests that the triplet formation mechanism involves an enhanced spin orbit coupling caused by sigma character in states at the 2-photon level. Symmetry Adapted Cluster-Configuration Interaction calculations produced excited state absorption spectra to provide guidance for estimating kinetic rates and the sigma character present in higher electronic states. It is concluded that higher excited state populations are significant when larger molecules are excited with pulsed lasers and need to be taken into account whenever discussing the molecular photodynamics

  19. Solvent-dependent excited-state hydrogen transfer and intersystem crossing in 2-(2′-hydroxyphenyl)-benzothiazole

    KAUST Repository

    Aly, Shawkat Mohammede

    2015-02-12

    The excited-state intramolecular hydrogen transfer (ESIHT) of 2-(2′-hydroxyphenyl) benzothiazole (HBT) has been investigated in a series of nonpolar, polar aprotic, and polar protic solvents. A variety of state-of-the-art experimental methods were employed, including femto- and nanosecond transient absorption and fluorescence upconversion spectroscopy with broadband capabilities. We show that the dynamics and mechanism of ESIHT of the singlet excited HBT are strongly solvent-dependent. In nonpolar solvents, the data demonstrate that HBT molecules adopt a closed form stabilized by O-H⋯N chelated hydrogen bonds with no twisting angle, and the photoinduced H transfer occurs within 120 fs, leading to the formation of a keto tautomer. In polar solvents, owing to dipole-dipole cross talk and hydrogen bonding interactions, the H transfer process is followed by ultrafast nonradiative deactivation channels, including ultrafast internal conversion (IC) and intersystem crossing (ISC). This is likely to be driven by the twisting motion around the C-C bond between the hydroxyphenyl and thiazole moieties, facilitating the IC back to the enol ground state or to the keto triplet state. In addition, our femtosecond time-resolved fluorescence experiments indicate, for the first time, that the lifetime of the enol form in ACN is approximately 280 fs. This observation indicates that the solvent plays a crucial role in breaking the H bond and deactivating the excited state of the HBT. Interestingly, the broadband transient absorption and fluorescence up-conversion data clearly demonstrate that the intermolecular proton transfer from the excited HBT to the DMSO solvent is about 190 fs, forming the HBT anion excited state.

  20. Isotope effect in dissociative electron attachment cross sections in acetylene

    Energy Technology Data Exchange (ETDEWEB)

    May, Olivier; Fedor, Juraj; Allan, Michael, E-mail: olivier.may@unifr.c [Department of Chemistry, University of Fribourg, Chemin du Muse 9, 1700 Fribourg (Switzerland)

    2009-11-01

    We present absolute cross section measurement of dissociative electron attachment to C{sub 2}H{sub 2} and C{sub 2}D{sub 2}. The C{sub 2}H{sup -}/ C{sub 2}D{sup -} band at 3 eV shows pronounced isotope effect with the cross section for C{sub 2}H{sub 2} being 14.7 times larger than that for C{sub 2}D{sub 2}. The light fragments H{sup -} and D{sup -} dominate the second dissociative electron attachment band around 8 eV. These bands exhibit much weaker isotope effects which is in agreement with their assignment to Feshbach resonances.

  1. The effect of intersystem crossings in N({sup 2}D) + H{sub 2} collisions

    Energy Technology Data Exchange (ETDEWEB)

    Galvão, B. R. L., E-mail: brenogalvao@gmail.com; Poveda, L. A. [Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais (Brazil)

    2015-05-14

    The transitions between quartet and doublet states of the NH{sub 2} molecule are studied for the first time, allowing the evaluation of the N({sup 4}S) + H{sub 2} reactive channel. High level ab initio calculations of the spin-orbit coupling are performed over the whole configurational space of the NH{sub 2} molecule and fitted to a proposed analytic form. Quasiclassical trajectories coupled with the surface hopping method are employed to calculate reaction cross section and rate constants. The reaction is largely affected by the initial rovibrational states of H{sub 2}, while the formation of long-lived complexes enhances the reaction probability.

  2. The effect of intersystem crossings in N(2D) + H2 collisions

    Science.gov (United States)

    Galvão, B. R. L.; Poveda, L. A.

    2015-05-01

    The transitions between quartet and doublet states of the NH2 molecule are studied for the first time, allowing the evaluation of the N(4S) + H2 reactive channel. High level ab initio calculations of the spin-orbit coupling are performed over the whole configurational space of the NH2 molecule and fitted to a proposed analytic form. Quasiclassical trajectories coupled with the surface hopping method are employed to calculate reaction cross section and rate constants. The reaction is largely affected by the initial rovibrational states of H2, while the formation of long-lived complexes enhances the reaction probability.

  3. Quantum confinement-tunable intersystem crossing and the triplet state lifetime of cationic porphyrin-CdTe quantum dot nano-assemblies

    KAUST Repository

    Ahmed, Ghada H.

    2015-01-01

    Here, we report a ground-state interaction between the positively charged cationic porphyrin and the negatively charged carboxylate groups of the thiol ligands on the surface of CdTe quantum dots (QDs), leading to the formation of a stable nanoassembly between the two components. Our time-resolved data clearly demonstrate that we can dramatically tune the intersystem crossing (ISC) and the triplet state lifetime of porphyrin by changing the size of the QDs in the nanoassembly. © 2015 The Royal Society of Chemistry.

  4. A quantum time-dependent wave-packet study of intersystem crossing effects in the O(3P0, 1, 2) + D2(v = 0, j = 0) reaction

    Science.gov (United States)

    Zhao, Juan

    2013-04-01

    We investigated spin-orbit-induced intersystem crossing effects in the title reaction by the time-dependent wave-packet method combined with an extended split operator scheme. We performed non-adiabatic calculations of the fine-structure-resolved cross section and adiabatic calculations of integral cross section. The calculations are based on the potential energy surfaces of 3A' and the two degenerate 3A'' states [S. Rogers, D. Wang, A. Kuppermann, and S. Walch, J. Phys. Chem. A 104, 2308 (2000)], 10.1021/jp992985g, together with the spin-orbit coupling matrix [B. Maiti and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)], 10.1063/1.1623481 and singlet 1A' potential energy surface [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)]. The results of the O(3P) + D2 are similar to those of the O(3P) + H2 reaction. The product spin state-resolved reaction cross section and the total reaction cross section both show that the adiabatic channel is dominant in all cases, and the non-adiabatic channels have cross sections of several orders of magnitude smaller than the adiabatic channels at high collision energy. Although the cross sections caused by the intersystem crossing effects in the O(3P) + D2 reaction are larger than those in the O(3P) + H2 reaction, the differences in non-adiabaticity between these two reaction systems are quite modest. Based on the results of the O(3P) + H2 reaction, we can predict that the influence of spin-orbit on the total reaction cross sections of the O(3P) + D2 reaction is also insignificant. However, these non-adiabatic effects can be reflected in the presence of some forward-scattering in the angular distribution for the OD product.

  5. Efficient triplet application in exciplex delayed-fluorescence OLEDs using a reverse intersystem crossing mechanism based on a ΔES-T of around zero.

    Science.gov (United States)

    Zhang, Tianyou; Chu, Bei; Li, Wenlian; Su, Zisheng; Peng, Qi Ming; Zhao, Bo; Luo, Yongshi; Jin, Fangming; Yan, Xingwu; Gao, Yuan; Wu, Hairuo; Zhang, Feng; Fan, Di; Wang, Junbo

    2014-08-13

    We demonstrate highly efficient exciplex delayed-fluorescence organic light-emitting diodes (OLEDs) in which 4,4',4″-tris[3-methylphenyl(phenyl)aminotriphenylamine (m-MTDATA) and 4,7-diphenyl-1,10-phenanthroline (Bphen) were selected as donor and acceptor components, respectively. Our m-MTDATA:Bphen exciplex electroluminescence (EL) mechanism is based on reverse intersystem crossing (RISC) from the triplet to singlet excited states. As a result, an external quantum efficiency (EQE) of 7.79% at 10 mA/cm(2) was observed, which increases by 3.2 and 1.5 times over that reported in Nat. Photonics 2012, 6, 253 and Appl. Phys. Lett. 2012, 101, 023306, respectively. The high EQE would be attributed to a very easy RISC process because the energy difference between the singlet and triplet excited states is almost around zero. The verdict was proven by photoluminescence (PL) rate analysis at different temperatures and time-resolved spectral analysis. Besides, the study of the transient PL process indicates that the presence of an unbalanced charge in exciplex EL devices is responsible for the low EQE and high-efficiency roll-off. When the exciplex devices were placed in a 100 mT magnetic field, the permanently positive magnetoelectroluminescence and magnetoconductivity were observed. The magnetic properties confirm that the efficient exciplex EL only originates from delayed fluorescence via RISC processes but is not related to the triplet-triplet annihilation process. PMID:24840782

  6. Reversibility of Intersystem Crossing in the {a}1A1(000) and {a}1A1(010) States of Methylene, CH_2

    Science.gov (United States)

    Le, Anh T.; Sears, Trevor; Hall, Gregory

    2015-06-01

    The lowest energy singlet ( {a}1A1) and triplet ( {X}3B1) electronic states of methylene, CH_2, are only separated by 3150 wn, but differ greatly in chemical reactivity. Overall methylene reaction rates and chemical behavior are therefore strongly dependent on collisionally-mediated singlet-triplet interconversion. Collisions with inert partners tend to depopulate the excited singlet state and populate vibrationally excited triplet levels in CH_2. This process is generally considered as irreversible for large molecules, however, this is not the case for small molecules such as CH_2. An investigation of the decay kinetics of CH_2 in the presence of argon and various amounts of oxygen has been carried out using transient frequency modulation (FM) absorption spectroscopy, to monitor ortho and para rotational levels in both the {a}1A1(000) and {a}1A1(010) states. In the {a}1A1(000) state, all observed rotational levels follow double exponential decay kinetics, a direct consequence of reversible intersystem crossing. The relative amplitude of the slower decay component is an indicator of how quickly the reverse crossing from excited triplet levels becomes significant during the reaction and relaxation of singlet methylene. The para rotational levels show more obvious signs of reversibility than ortho rotational levels. Adding oxygen enhances the visibility of reversibility for both ortho and para levels. However, in the {a}1A1(010) state where the FM signal is 5-10 times smaller than the {a}1A1(000) state, there is no evidence of double exponential decay kinetics. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 and DE-SC0012704 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

  7. The lowest quartet-state of the ketenyl (HCCO) radical: Collision-induced intersystem crossing and the ν2 vibrational mode

    International Nuclear Information System (INIS)

    Graphical abstract: Generation, transformation, deactivation, and loss of the ketenyl radical. Highlights: • ISC rate constants measured for lowest cis-quartet-state HCCO with He, Ar, and Xe. • Ar and Xe induced ISC shown to exhibit an external heavy atom effect. • He observed to be more effective at vibrational deactivation than inducing ISC. • First experimental observation of nu2 mode of cis-quartet-state HCCO at 1785 ± 36 cm−1. - Abstract: We have used time-resolved IR emission spectroscopy to examine collision induced intersystem crossing (CIISC) and deactivation of vibronically excited cis-HCCO(a-tilde4A″), generated following the 193 nm photolysis of ethyl ethynyl ether, by inert gases: He, Ar, and Xe. Observation of vibrationally excited CO(X1Σ+), in experiments quenched with Ar or Xe, suggest rapid CIISC due to a heavy-atom effect. Conversely, experiments quenched with He show transient signal from cis-HCCO(a-tilde4A″), and a distinct absence of CO(X1Σ+), suggesting that CIISC occurs only after cis-HCCO(a-tilde4A″) has been quenched (i.e., CIISC is significantly less efficient with He). Inert gas CIISC rate constants for cis-HCCO(a-tilde4A″) were deduced to be kISCHe=(4.3±0.2)×10−11 cm3molecules-1s-1, kISCAr=(8.1±0.2)×10−11 cm3molecules-1s-1, and kISCXe=(13.0±0.1)×10−11 cm3molecules-1s-1. Additionally, we report the first experimental assignment of 1785 ± 36 cm−1 for the fundamental transition of the ν2 asym-CCO stretch of cis-HCCO(a-tilde4A″), which, compared with ab initio calculations, suggests that cis-HCCO(a-tilde4A″) exhibits positive anharmonicity

  8. Experimental and theoretical studies of the O(3P) + C2H4 reaction dynamics: collision energy dependence of branching ratios and extent of intersystem crossing.

    Science.gov (United States)

    Fu, Bina; Han, Yong-Chang; Bowman, Joel M; Leonori, Francesca; Balucani, Nadia; Angelucci, Luca; Occhiogrosso, Angela; Petrucci, Raffaele; Casavecchia, Piergiorgio

    2012-12-14

    The reaction of O((3)P) with C(2)H(4), of importance in combustion and atmospheric chemistry, stands out as paradigm reaction involving not only the indicated triplet state potential energy surface (PES) but also an interleaved singlet PES that is coupled to the triplet surface. This reaction poses great challenges for theory and experiment, owing to the ruggedness and high dimensionality of these potentials, as well as the long lifetimes of the collision complexes. Crossed molecular beam (CMB) scattering experiments with soft electron ionization detection are used to disentangle the dynamics of this polyatomic multichannel reaction at a collision energy E(c) of 8.4 kcal∕mol. Five different primary products have been identified and characterized, which correspond to the five exothermic competing channels leading to H + CH(2)CHO, H + CH(3)CO, CH(3) + HCO, CH(2) + H(2)CO, and H(2) + CH(2)CO. These experiments extend our previous CMB work at higher collision energy (E(c) ∼ 13 kcal∕mol) and when the results are combined with the literature branching ratios from kinetics experiments at room temperature (E(c) ∼ 1 kcal∕mol), permit to explore the variation of the branching ratios over a wide range of collision energies. In a synergistic fashion, full-dimensional, QCT surface hopping calculations of the O((3)P) + C(2)H(4) reaction using ab initio PESs for the singlet and triplet states and their coupling, are reported at collision energies corresponding to the CMB and the kinetics ones. Both theory and experiment find almost an equal contribution from the triplet and singlet surfaces to the reaction, as seen from the collision energy dependence of branching ratios of product channels and extent of intersystem crossing (ISC). Further detailed comparisons at the level of angular distributions and translational energy distributions are made between theory and experiment for the three primary radical channel products, H + CH(2)CHO, CH(3) + HCO, and CH(2) + H(2)CO

  9. Photon statistics of driven single molecule: The effects of intersystem crossing process%单分子发射光子的统计性质:考虑系间穿越影响

    Institute of Scientific and Technical Information of China (English)

    古丽姗; 宋艺华; 彭勇刚; 郑雨军

    2011-01-01

    用产生函数(generating function)方法研究了单分子存在系间穿越过程的发射光子的统计性质,并给出了长时间极限下的发射光子的平均值以及对应的Mandel Q参数的表达式.研究结果表明,在系间穿越过程存在的情况下,单分子发射光子的平均发射光子数 and the Mandel's Q parameter in long time limit. The results demonstrate that the Mandel's Q parameter has the same behavior as the average emission photons with respect to the evolution time, both of them linearly increasing with the evolution time increase, when the intersystem crossing process occurred in the single molecule.

  10. Reaction Dynamics of O((3)P) + Propyne: II. Primary Products, Branching Ratios, and Role of Intersystem Crossing from Ab Initio Coupled Triplet/Singlet Potential Energy Surfaces and Statistical Calculations.

    Science.gov (United States)

    Gimondi, Ilaria; Cavallotti, Carlo; Vanuzzo, Gianmarco; Balucani, Nadia; Casavecchia, Piergiorgio

    2016-07-14

    The mechanism of the O((3)P) + CH3CCH reaction was investigated using a combined experimental/theoretical approach. Experimentally the reaction dynamics was studied using crossed molecular beams (CMB) with mass-spectrometric detection and time-of-flight analysis at 9.2 kcal/mol collision energy. Theoretically master equation (ME) simulations were performed on a potential energy surface (PES) determined using high-level ab initio electronic structure calculations. In this paper (II) the theoretical results are described and compared with experiments, while in paper (I) are reported and discussed the results of the experimental study. The PES was investigated by determining structures and vibrational frequencies of wells and transition states at the CASPT2/aug-cc-pVTZ level using a minimal active space. Energies were then determined at the CASPT2 level increasing systematically the active space and at the CCSD(T) level extrapolating to the complete basis set limit. Two separate portions of the triplet PES were investigated, as O((3)P) can add either on the terminal or the central carbon of the unsaturated propyne bond. Minimum energy crossing points (MECPs) between the triplet and singlet PESs were searched at the CASPT2 level. The calculated spin-orbit coupling constants between the T1 and S0 electronic surfaces were ∼25 cm(-1) for both PESs. The portions of the singlet PES that can be accessed from the MECPs were investigated at the same level of theory. The system reactivity was predicted integrating stochastically the one-dimensional ME using Rice-Ramsperger-Kassel-Marcus theory to determine rate constants on the full T1/S0 PESs, accounting explicitly for intersystem crossing (ISC) using the Landau-Zener model. The computational results are compared both with the branching ratios (BRs) determined experimentally in the companion paper (I) and with those estimated in a recent kinetic study at 298 K. The ME results allow to interpret the main system reactivity: CH

  11. A mid-infrared absorption diagnostic for acetylene detection

    KAUST Repository

    KC, Utsav

    2015-05-14

    Acetylene is an important combustion intermediate and plays a critical role in soot formation. Accurate measurements of trace concentrations of acetylene can be very useful in validating hydrocarbon oxidation and soot formation mechanisms. Strongest vibrational band of acetylene near 13.7 μm is probed here to develop a highly sensitive absorption diagnostic. Experiments are carried out behind reflected shock waves to measure absorption cross sections of acetylene near 730 cm−1 over a wide range of temperatures (1000–2200 K) and pressures (1–5 bar). The diagnostic is demonstrated by measuring acetylene formation during the shock-heated pyrolysis and oxidation of propene. © 2015 Springer-Verlag Berlin Heidelberg

  12. Crossed beam reaction of the cyanogen radical, CN(X 2Σ+), with acetylene, C2H2(X 1Σg+): Observation of cyanoacetylene, HCCCN(X 1Σ+)

    Science.gov (United States)

    Huang, L. C. L.; Lee, Y. T.; Kaiser, R. I.

    1999-04-01

    The chemical dynamics to cyanoacetylene, HCCCN(X 1Σ+), formation via the neutral-neutral reaction of cyanogen, CN(X 2Σ+), with acetylene, C2H2(X 1Σg+), is investigated in a crossed molecular beams experiment at a collision energy of 21.1 kJ mol-1. The laboratory angular distribution and time-of-flight spectra of the HCCCN product are recorded at m/e=51 and 50. Forward-convolution fitting of our data reveals that the reaction dynamics are governed by an initial attack of the CN radical to the π electron density of the acetylene molecule to form a HCCHCN collision complex on the 2A' surface. The four heavy atoms are rotating in plane almost perpendicular to the total angular momentum vector J around the C axis of the complex which undergoes C-H bond rupture through a tight transition state to HCCCN and H. The H atom is emitted almost perpendicular to the HCCCN axis to yield a nearly "sideways" peaking of T(θ). The explicit identification of the cyanoacetylene reaction product represents a solid 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 rich planets and satellites such as the Saturnian moon Titan.

  13. Acetylene on Titan

    Science.gov (United States)

    Singh, Sandeep; McCord, Thomas B.; Combe, Jean-Philippe; Rodriguez, Sebastien; Cornet, Thomas; Le Mouélic, Stéphane; Clark, Roger Nelson; Maltagliati, Luca; Chevrier, Vincent

    2016-10-01

    Saturn's moon Titan possesses a thick atmosphere that is mainly composed of N2 (98%), CH4 (2 % overall, but 4.9% close to the surface) and less than 1% of minor species, mostly hydrocarbons [1]. A dissociation of N2 and CH4 forms complex hydrocarbons in the atmsophere and acetylene (C2H2) and ethane (C2H6) are produced most abundently. Since years, C2H2 has been speculated to exist on the surface of Titan based on its high production rate in the stratosphere predicted by photochemical models [2,3] and from its detection as trace gas sublimated/evaporated from the surface after the landing of the Huygens probe by the Gas Chromatograph Mass Spectrometer (GCMS) [1]. Here we show evidence of acetylene (C2H2) on the surface of Titan by detecting absorption bands at 1.55 µm and 4.93 µm using Cassini Visual and Infrared Mapping Spectrometer (VIMS) [4] at equatorial areas of eastern Shangri-La, and Fensal-Aztlan/Quivira.An anti-correlation of absorption band strength with albedo indicates greater concentrations of C2H2 in the dark terrains, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.References:[1]Niemann et al., Nature 438, 779–784 (2005).[2]Lavvas et al., Planetary and Space Science 56, 67 – 99 (2008).[3]Lavvas et al., Planetary and Space Science 56, 27 – 66 (2008).[4] Brown et al., The Cassini-Huygens Mission 111–168 (Springer, 2004).

  14. Transition probability of the Al II 2669 intersystem line

    Science.gov (United States)

    Johnson, B. C.; Smith, P. L.; Parkinson, W. H.

    1986-01-01

    Time-resolved observations of the spin-changing, or 'intersystem' emission at 2669.157 A obtained by the ion storage technique are used to measure the transition probability of the 3s2 1S0 - 3s3p 3P1 exp 0 line in Al II. A laser-generated plasma was used as the source of the metastable Al(+) ions. The A-value result obtained for the intersystem transition is 3.33 + or - 0.23 x 10 to the 3rd/sec at the 90-percent confidence level; this value is used to derive two line-intensity ratios which involve the intersystem line as a function of electron density and temperature.

  15. Crossed beam reaction of cyano radicals with hydrocarbon molecules. IV. Chemical dynamics of cyanoacetylene (HCCCN; X 1Σ+) formation from reaction of CN(X 2Σ+) with acetylene, C2H2(X 1Σg+)

    Science.gov (United States)

    Huang, L. C. L.; Asvany, O.; Chang, A. H. H.; Balucani, N.; Lin, S. H.; Lee, Y. T.; Kaiser, R. I.; Osamura, Y.

    2000-11-01

    The chemical reaction dynamics to form cyanoacetylene, HCCCN (X 1Σ+), via the radical-neutral reaction of cyano radicals, CN(X 2Σ+;ν=0), with acetylene, C2H2(X 1Σg+), are unraveled in crossed molecular beam experiments at two collision energies of 21.1 and 27.0 kJ mol-1. Laboratory angular distributions and time-of-flight spectra of the HCCCN product are recorded at m/e=51 and 50. Experiments were supplemented by electronic structure calculations on the doublet C3H2N potential energy surface and RRKM investigations. Forward-convolution fitting of the crossed beam data combined with our theoretical investigations shows that the reaction has no entrance barrier and is initiated by an attack of the CN radical to the π electron density of the acetylene molecule to form a doublet cis/trans HCCHCN collision complex on the 2A' surface via indirect reactive scattering dynamics. Here 85% of the collision complexes undergo C-H bond rupture through a tight transition state located 22 kJ mol-1 above the cyanoacetylene, HCCCN (X 1Σ+) and H(2S1/2) products (microchannel 1). To a minor amount (15%) trans HCCHCN shows a 1,2-H shift via a 177 kJ mol-1 barrier to form a doublet H2CCCN radical, which is 46 kJ mol-1 more stable than the initial reaction intermediate (microchannel 2). The H2CCCN complex decomposes via a rather loose exit transition state situated only 7 kJ mol-1 above the reaction products HCCCN (X 1Σ+) and H(2S1/2). In both cases the geometry of the exit transition states is reflected in the observed center-of-mass angular distributions showing a mild forward/sideways peaking. The explicit identification of the cyanoacetylene as the only reaction product represents a solid background for the title reaction to be included 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 rich planets and satellites such as the Saturnian moon Titan.

  16. A statistical characterization of the Galileo-to-GPS inter-system bias

    Science.gov (United States)

    Gioia, Ciro; Borio, Daniele

    2016-06-01

    Global navigation satellite system operates using independent time scales and thus inter-system time offsets have to be determined to enable multi-constellation navigation solutions. GPS/Galileo inter-system bias and drift are evaluated here using different types of receivers: two mass market and two professional receivers. Moreover, three different approaches are considered for the inter-system bias determination: in the first one, the broadcast Galileo to GPS time offset is used to align GPS and Galileo time scales. In the second, the inter-system bias is included in the multi-constellation navigation solution and is estimated using the measurements available. Finally, an enhanced algorithm using constraints on the inter-system bias time evolution is proposed. The inter-system bias estimates obtained with the different approaches are analysed and their stability is experimentally evaluated using the Allan deviation. The impact of the inter-system bias on the position velocity time solution is also considered and the performance of the approaches analysed is evaluated in terms of standard deviation and mean errors for both horizontal and vertical components. From the experiments, it emerges that the inter-system bias is very stable and that the use of constraints, modelling the GPS/Galileo inter-system bias behaviour, significantly improves the performance of multi-constellation navigation.

  17. A statistical characterization of the Galileo-to-GPS inter-system bias

    Science.gov (United States)

    Gioia, Ciro; Borio, Daniele

    2016-11-01

    Global navigation satellite system operates using independent time scales and thus inter-system time offsets have to be determined to enable multi-constellation navigation solutions. GPS/Galileo inter-system bias and drift are evaluated here using different types of receivers: two mass market and two professional receivers. Moreover, three different approaches are considered for the inter-system bias determination: in the first one, the broadcast Galileo to GPS time offset is used to align GPS and Galileo time scales. In the second, the inter-system bias is included in the multi-constellation navigation solution and is estimated using the measurements available. Finally, an enhanced algorithm using constraints on the inter-system bias time evolution is proposed. The inter-system bias estimates obtained with the different approaches are analysed and their stability is experimentally evaluated using the Allan deviation. The impact of the inter-system bias on the position velocity time solution is also considered and the performance of the approaches analysed is evaluated in terms of standard deviation and mean errors for both horizontal and vertical components. From the experiments, it emerges that the inter-system bias is very stable and that the use of constraints, modelling the GPS/Galileo inter-system bias behaviour, significantly improves the performance of multi-constellation navigation.

  18. Plasma Thermal Conversion of Methane to Acetylene

    International Nuclear Information System (INIS)

    This paper describes a re-examination of a known process for the direct plasma thermal conversion of methane to acetylene. Conversion efficiencies (% methane converted) approached 100% and acetylene yields in the 90-95% range with 2-4% solid carbon production were demonstrated. Specificity for acetylene was higher than in prior work. Improvements in conversion efficiency, yield, and specificity were due primarily to improved injector design and reactant mixing, and minimization of temperature gradients and cold boundary layers. At the 60-kilowatt scale cooling by wall heat transfer appears to be sufficient to quench the product stream and prevent further reaction of acetylene resulting in the formation of heavier hydrocarbon products or solid carbon. Significantly increasing the quenching rate by aerodynamic expansion of the products through a converging-diverging nozzle led to a reduction in the yield of ethylene but had little effect on the yield of other hydrocarbon products. While greater product selectivity for acetylene has been demonstrated, the specific energy consumption per unit mass of acetylene produced was not improved upon. A kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons, through benzene, is described

  19. Acetylene diffusion in Na-Y zeolite

    Indian Academy of Sciences (India)

    S Mitra; S Sumitra; A M Umarji; R Mukhopadhyay; S Yashonath; S L Chaplot

    2004-08-01

    Study of diffusivity of acetylene adsorbed in Na-Y zeolite by quasi-elastic neutron scattering (QENS) measurements at temperatures of 300, 325 and 350 K is reported. A model in which the acetylene molecules undergo random-walk diffusion characterized by a Gaussian distribution of jump lengths inside zeolite cages describes the data consistently. The diffusion constant, residence time between jumps and root mean square jump length are determined.

  20. Theoretical Determination of Electronic Spectra and Intersystem Spin-Orbit Coupling: The Case of Isoindole-BODIPY Dyes.

    Science.gov (United States)

    Alberto, Marta E; De Simone, Bruna C; Mazzone, Gloria; Quartarolo, Angelo D; Russo, Nino

    2014-09-01

    Density functional theory and its time-dependent extension (DFT, TDDFT) has been herein employed to elucidate the structural and electronic properties for a series of isoindole-boron dipyrromethene (isoindole-BODIPY) derivatives. The role played by both the nature and the positions of the substituents on intersystem spin-crossing has been investigated computing the spin-orbit matrix elements between singlet and triplet excited state wave functions weighted by the TDDFT transition coefficients. Their potential therapeutic use as photosensitizers in photodynamic therapy (PDT) is proposed on the basis of their strong absorbance in the red part of the visible spectrum, vertical triplet energies resulting higher than 0.98 eV, and the spin-orbit matrix elements that result to be comparable with different drugs already used in PDT. PMID:26588544

  1. Vapor pressures of acetylene at low temperatures

    Science.gov (United States)

    Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

    1990-01-01

    The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

  2. Microporous metal–organic framework with dual functionalities for highly efficient removal of acetylene from ethylene/acetylene mixtures

    KAUST Repository

    Hu, Tong-Liang

    2015-06-04

    The removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene is a technologically very important, but highly challenging task. Current removal approaches include the partial hydrogenation over a noble metal catalyst and the solvent extraction of cracked olefins, both of which are cost and energy consumptive. Here we report a microporous metal–organic framework in which the suitable pore/cage spaces preferentially take up much more acetylene than ethylene while the functional amine groups on the pore/cage surfaces further enforce their interactions with acetylene molecules, leading to its superior performance for this separation. The single X-ray diffraction studies, temperature dependent gas sorption isotherms, simulated and experimental column breakthrough curves and molecular simulation studies collaboratively support the claim, underlying the potential of this material for the industrial usage of the removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene at room temperature through the cost- and energy-efficient adsorption separation process.

  3. Influence of and additives on acetylene detonation

    Science.gov (United States)

    Drakon, A.; Emelianov, A.; Eremin, A.

    2014-03-01

    The influence of and admixtures (known as detonation suppressors for combustible mixtures) on the development of acetylene detonation was experimentally investigated in a shock tube. The time-resolved images of detonation wave development and propagation were registered using a high-speed streak camera. Shock wave velocity and pressure profiles were measured by five calibrated piezoelectric gauges and the formation of condensed particles was detected by laser light extinction. The induction time of detonation development was determined as the moment of a pressure rise at the end plate of the shock tube. It was shown that additive had no influence on the induction time. For , a significant promoting effect was observed. A simplified kinetic model was suggested and characteristic rates of diacetylene formation were estimated as the limiting stage of acetylene polymerisation. An analysis of the obtained data indicated that the promoting species is atomic chlorine formed by pyrolysis, which interacts with acetylene and produces radical, initiating a chain mechanism of acetylene decomposition. The results of kinetic modelling agree well with the experimental data.

  4. Radical recombinations in acetylene-air flames

    NARCIS (Netherlands)

    Zeegers, P.J.Th.; Alkemade, C.T.J.

    1965-01-01

    In this paper an analysis is given of the behaviour of excess radical concentrations, H, OH and O as a function of height above the reaction zone in premixed acetylene-air flames at 2–200° to 2400°K and 1 atmosphere pressure. The intensity was measured of the Li resonance line which is related to th

  5. Two new acetylenic compounds from Asparagus officinalis.

    Science.gov (United States)

    Li, Xue-Mei; Cai, Jin-Long; Wang, Wen-Xiang; Ai, Hong-Lian; Mao, Zi-Chao

    2016-01-01

    Two new acetylenic compounds, asparoffins A (1) and B (2), together with two known compounds, nyasol (3) and 3″-methoxynyasol (4), were isolated from stems of Asparagus officinalis. The structures of two new compounds were elucidated on the basis of detailed spectroscopic analyses (UV, IR, MS, 1D, and 2D NMR). All compounds were evaluated for their cytotoxicities against three human cancer cell lines.

  6. Two new acetylenic compounds from Asparagus officinalis.

    Science.gov (United States)

    Li, Xue-Mei; Cai, Jin-Long; Wang, Wen-Xiang; Ai, Hong-Lian; Mao, Zi-Chao

    2016-01-01

    Two new acetylenic compounds, asparoffins A (1) and B (2), together with two known compounds, nyasol (3) and 3″-methoxynyasol (4), were isolated from stems of Asparagus officinalis. The structures of two new compounds were elucidated on the basis of detailed spectroscopic analyses (UV, IR, MS, 1D, and 2D NMR). All compounds were evaluated for their cytotoxicities against three human cancer cell lines. PMID:26558641

  7. CO2 laser-driven reactions in pure acetylene flow

    CERN Document Server

    Pikhitsa, Peter V; Choi, Mansoo

    2011-01-01

    We show that multiple-photon absorption of radiation from a 10.56 {\\mu}m cw CO2 laser by intermediates (ethylene, vinylidene) generated in pure acetylene flow makes them decompose to carbon dimers and excited hydrogen. The latter associates with downstream acetylene to feedback those laser absorbing intermediates thus making the reactions self-sustained in the absence of oxygen. This process is different from acetylene self-decomposition that may occur at higher temperature and pressure. The results of our work may be useful for understanding the generation of various carbon allotropes and interstellar dust from acetylene.

  8. Synthesis of acetylenic derivatives of hydroxynaphthoquinone

    International Nuclear Information System (INIS)

    The acetylene derivatives synthesis 2-hydroxy-1 ,4-naphthoquinones was studied using different reaction conditions: coupling with copper and silver acetylides, Sonogashira reaction with and without CU (I) as cocatalyst. The reaction conditions are optimized for coupling of iodine lawson and ylide phenyl lawsone of iodine with various terminal acetylenes: phenyl acetylene, propargyl alcohol, 1-heptin and 2-methyl-3-butyne-2-ol. Also, reactants such as bromides of hidroxinaphthoquinones were used with protecting groups such as acetate, methoxy, phenyloxy, benzyloxy and tricloroetoxy. The synthesis of 2-hydroxy-3-(3-hydroxy-3-ynyl-1-methylbutane)-1,4-naphthoquinone, 2-methoxy-3-(2-phenylethynyl) -1,4-naphthoquinone and 2-(2-phenylethynyl)-3-(2,2,2-tricloroetoxy)-1,4-naphthoquinone was performed with rates of return of 22%, 57% and 67% respectively. The reaction of the yodolawsona was obtained with 3-chloro-3-methyl-1-butyne in the presence of CuI, CsI and Cs2Co3 obtaining the enol ether: 3,3-dimethyl-2-methyl-2 ,3-dihydronaphto [2 ,3-b]furan-4,9-dione (dehydro-α-dunion), with a rate of return of 58%. This enol ether was used as a reactant for the formation, through a regioselective hydrogenation with PtO2/t-butanol of α-dunion with a yield of 50%. Furthermore, by acid hydrolysis with H2SO4 has been possible to obtain a percentage yield of 75% streptocarpone. Both, α-dunion and streptocarpone, natural products extracted from Streptocarpus dunni shrub, with antiparasitic activity, and which so far had not presented an efficient synthesis. A mechanism is proposed for the reaction of formation of the enol ether where it is presumed the presence of a zwitterion-vinyl carbene as key intermediate of the reaction. All products were characterized by spectroscopy 1H and 13C-NMR, UV-Vis and IR. (author)

  9. Acetylenic polymers for hair styling products.

    Science.gov (United States)

    Martiny, S

    2002-06-01

    This paper looks at the basic requirements of hair styling products from a consumer's perspective before moving onto a very brief outline of the various chemistries available to the formulator. It then discusses the manufacture of vinyl pyrrolidone from acetylene. The properties of polyvinyl pyrrolidone are described, followed by the features and benefits of some vinyl pyrrolidone copolymers and terpolymers. The instrumental analysis of the hold, flexibility, tack and combing properties of polymer films is discussed in some detail, along with the effect of application type on these measurable properties concentrating upon vinyl caprolactam/vinyl pyrrolidone/dimethylaminopropyl methacrylamide acrylates copolymer.

  10. Largest Experimental Facility for Acetylene Production in Operation

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Scientists from the CAS Institute of Plasma Physics (IPP) completed in early November, 2004, a 2-megawatt experimental facility for acetylene production by coal plasma pyrolysis. The successful operation of the largest installation of the kind in the world confirms a new method for the large-scale industrialization of acetylene production.

  11. 76 FR 75782 - Revising Standards Referenced in the Acetylene Standard

    Science.gov (United States)

    2011-12-05

    ... organizations (``SDO standards'') (69 FR 68283). A SDO standard referenced in OSHA's Acetylene Standard (29 CFR... of the Compressed Gas Association standard, CGA G-1-2003, in the Acetylene Standard. See 74 FR 40442... appropriate, revoke references to outdated national SDO standards in OSHA rules (see, e.g., 69 FR 68283, 70......

  12. Acetylene-Based Materials in Organic Photovoltaics

    Directory of Open Access Journals (Sweden)

    Fabio Silvestri

    2010-04-01

    Full Text Available Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (polyarylacetylenes that have been used in the field. A general introduction to (polyarylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (copolymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C60, and their use as the active materials in photovoltaic devices.

  13. Diamond growth in oxygen-acetylene flame

    International Nuclear Information System (INIS)

    What was supposed to be a laboratory curiosity in the 80's, in recent years the low pressure process for the production of man-made diamond turned out to be a major target for research and development of many high-tech companies. The main reason for such an interest stems on the possibility of coating many materials with a diamond film possessing the same amazing properties of the bulk natural diamond. Polycrystalline diamond film has been deposited on Mo substrate by using oxygen-acetylene flame of a welding torch. The substrate temperature has been held constant about 700deg C by means of a water cooled mount designed properly. Precision flowmeters have been used to control the flow ratio oxygen/acetylene, a key parameter for the success in diamond growth. Diamond has been detected by X-ray diffraction, a fast foolproof technique for crystal identification. Another method of analysis often used in Raman spectroscopy, which is able to exhibit amorphous structure besides crystalline phase. (author)

  14. Acetylene-based materials in organic photovoltaics.

    Science.gov (United States)

    Silvestri, Fabio; Marrocchi, Assunta

    2010-04-08

    Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (poly)arylacetylenes that have been used in the field. A general introduction to (poly)arylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (co)polymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C(60), and their use as the active materials in photovoltaic devices.

  15. Synthesis and Antifeeding Activity of Acetylene-Containing Tonghaosu Analogs

    Institute of Scientific and Technical Information of China (English)

    CHEN,Li; HU,Tai-Shan; XU,Han-Hong; YIN,Biao-Lin; XIAO,Chun; WU,Yu-Lin

    2004-01-01

    @@ During our continuous efforts towards the search for environmental benign insect antifeedant, we established a concise method for the synthesis of Tonghaosu, a naturally occurring antifeedant.[1] Herein, we report the synthesis and antifeeding activity of 22 new tonghaosu analogs, which contain varied B ring as well as one or two acetylene functionalities. Preliminary bioassay indicates that two acetylene groups containing tonghaosu analogs have better antifeedant activity against large white butterfly (Pieris brassicae L.) than those with one acetylene group. More interestingly,Z-isomers are much more active than their corresponding E-isomers.

  16. CHIRAL CONJUGATED OLIGOMER BASED ON 1,1'-BINOL WITH 3,3'-ACETYLENE-PHENYLENE-ACETYLENE SPACER

    Institute of Scientific and Technical Information of China (English)

    Tian-jun Liu; Ke-shen Zhang; Yong-jun Chen; Dong Wang; Chao-jun Li

    2001-01-01

    The 1,1'-binaphthol based oligomers 3 and 7 with 3,3'-acetylene-phenylene-acetylene spacer were prepared from BINOL 1. The high optical rotation value and CD spectra demonstrated the main chain chirality of the oligomer molecule. The UV-VIS and fluorescent spectra evidence the characteristics of conjugated structure. In comparison with oligomer 2 bearing 3,3'-acetylene spacer, the oligomers 3 and 7 have longer efficient conjugation segment, and their fluorescent quantum yields (φ) increased (0.60-0.65 versus 0.14). Extending the effective conjugation segment would improve the photophysical properties of chiral conjugated polymers.``

  17. Self-condensation of Terminal Acetylenic Ketones vta Organozinc Species

    Institute of Scientific and Technical Information of China (English)

    GAO Jun-Li; LIU Yong-Kang; XUE Song

    2008-01-01

    A self-condensation reaction of a,β-acetylenic ketones via organozinc species CF3CO2ZnEt to afford the β-branched Morita-Baylfis-Hillman adducts has been developed.This reaction system provides functionalized trisubstituted olefins in good yields.Organozinc species CF3CO2ZnCH2I,an efficient cyclopropanation reagent,can also react with aromatic acetylenic ketones to provide 2,5-dihydrofurans in moderate yields.

  18. PLASMA POLYMERIZATION OF ACETYLENE/CO2/H2

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ji; FANG Yuee; SHI Tianyi; SHOHEI INOUE

    1989-01-01

    A study has been made on the plasma polymerization of acetylene/CO2/H2 in a capacitively coupled RF plasma. The monomer mixture yielded a crosslinked film with light brown color. A kinetic study is reported for the plasma polymerization of acetylene/CO2/H2. The effects of discharge power level and reactor geometry on the rate of polymer formation are reported. The structure of the plasma polymer is investigated by IR study.

  19. Ultrafast Intersystem-Crossing Dynamics and Breakdown of the Kasha-Vavilov's Rule of Naphthalenediimides.

    Science.gov (United States)

    Yushchenko, Oleksandr; Licari, Giuseppe; Mosquera-Vazquez, Sandra; Sakai, Naomi; Matile, Stefan; Vauthey, Eric

    2015-06-01

    The fluorescence quantum yield of a red naphthalenediimide dye (rNDI) with amino and Br core substituents has been found to decrease by a factor of almost 2 by going from S1 ← S0 to S2 ← S0 excitation. Time-resolved spectroscopic measurements reveal that this deviation from the Kasha-Vavilov's rule is due to an ultrafast, naphthalenediimide (pNDI), ISC is slower, ∼2 ps, and was found to be reversible on a time scale shorter than that of vibrational cooling. The fluorescence and triplet quantum yields of rNDI, thus, can be substantially changed by a simple variation of the excitation wavelength. PMID:26266508

  20. High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8μm

    KAUST Repository

    Sajid, M.B.

    2015-04-01

    The mid-infrared wavelength region near 8 mu m contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the v(4) band of methane and the v(4)+v(5) band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm(-1)) and P23 (1275.5 cm(-1)) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200-2200 K, between pressures of 1-4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane. (C) 2015 Elsevier Ltd. All rights reserved.

  1. Acetylene on Titan’s Surface

    Science.gov (United States)

    Singh, S.; McCord, T. B.; Combe, J.-Ph.; Rodriguez, S.; Cornet, T.; Le Mouélic, S.; Clark, R. N.; Maltagliati, L.; Chevrier, V. F.

    2016-09-01

    Titan’s atmosphere is opaque in the near-infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few “transparency windows.” Thus, the composition of Titan’s surface remains difficult to access from space and is still poorly constrained. Photochemical models suggest that most of the organic compounds formed in the atmosphere are heavy enough to condense and build up at the surface in liquid and solid states over geological timescales. Acetylene (C2H2) net production in the atmosphere is predicted to be larger than any other compound and C2H2 has been speculated to exist on the surface of Titan. C2H2 was detected as a trace gas sublimated/evaporated from the surface using the Gas Chromatograph Mass Spectrometer after the landing of the Huygens probe. Here we show evidence of C2H2 on the surface of Titan by detecting absorption bands at 1.55 and 4.93 μm using the Cassini Visual and Infrared Mapping Spectrometer at three different equatorial areas—Tui Regio, eastern Shangri La, and Fensal–Aztlan/Quivira. We found that C2H2 is preferentially detected in low-albedo areas, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.

  2. INTERSYSTEM INTEGRATION IN TERMS OF THE EDUCATIONAL PROCESS IN THE INITIAL COURSES OF HIGHER MEDICAL SCHOOL.

    Science.gov (United States)

    Marakushin, D; Chernobay, L; Vasylieva, O; Karmazina, I

    2016-07-01

    The study was conducted as part of research work «Features of integrative and autonomic functions in the process of adaptation to the intellectual, emotional and physical stress" of the Department of Physiology of KhNMU. The aim of this work was to study the intersystem relationships that are the basis for the development of the body's resistance to the effects of stress factors, i.e., the development of adaptation syndrome in medical students. The object of the study were 217 students of 1-3 courses, which were examined in terms of the educational process. The features of intersystem integration the cardiorespiratory system on the basis of conjugation and integration of brain activity indeces based on intellectual efficiency in terms of a correction test. The study of the psychophysiological indicators complex in dynamics (3 years) revealed the formation of chronic emotional stress in medical students, the severity of which depends on the individual psychophysiological status of students. It was set that the formation of the adaptive optimum with psychoemotional stress occurs in only in 40% of students. Most of the students (60 %) indicate or initially insufficient adaptive capabilities, or an excessive rate, which naturally lead to psychological and autonomic disturbances in the organism.

  3. INTERSYSTEM INTEGRATION IN TERMS OF THE EDUCATIONAL PROCESS IN THE INITIAL COURSES OF HIGHER MEDICAL SCHOOL.

    Science.gov (United States)

    Marakushin, D; Chernobay, L; Vasylieva, O; Karmazina, I

    2016-07-01

    The study was conducted as part of research work «Features of integrative and autonomic functions in the process of adaptation to the intellectual, emotional and physical stress" of the Department of Physiology of KhNMU. The aim of this work was to study the intersystem relationships that are the basis for the development of the body's resistance to the effects of stress factors, i.e., the development of adaptation syndrome in medical students. The object of the study were 217 students of 1-3 courses, which were examined in terms of the educational process. The features of intersystem integration the cardiorespiratory system on the basis of conjugation and integration of brain activity indeces based on intellectual efficiency in terms of a correction test. The study of the psychophysiological indicators complex in dynamics (3 years) revealed the formation of chronic emotional stress in medical students, the severity of which depends on the individual psychophysiological status of students. It was set that the formation of the adaptive optimum with psychoemotional stress occurs in only in 40% of students. Most of the students (60 %) indicate or initially insufficient adaptive capabilities, or an excessive rate, which naturally lead to psychological and autonomic disturbances in the organism. PMID:27661283

  4. Measurement of the transition probability of the C III 190.9 nanometer intersystem line

    Science.gov (United States)

    Kwong, Victor H. S.; Fang, Z.; Gibbons, T. T.; Parkinson, W. H.; Smith, Peter L.

    1993-01-01

    A radio-frequency ion trap has been used to store C(2+) ions created by electron bombardment of CO. The transition probability for the 2s2p 3Po1-2s2 1S0 intersystem line of C m has been measured by recording the radiative decay at 190.9 nm. The measured A-value is 121 +/- 7/s and agrees, within mutual uncertainty limits, with that of Laughlin et al. (1978), but is 20 percent larger than that of Nussbaumer and Storey (1978). The effective collision mixing rate coefficient among the fine structure levels of 3Po and the combined quenching and charge transfer rate coefficients out of the 3Po1 level with the CO source gas have also been measured.

  5. Channel-resolved above-threshold double ionization of acetylene.

    Science.gov (United States)

    Gong, Xiaochun; Song, Qiying; Ji, Qinying; Lin, Kang; Pan, Haifeng; Ding, Jingxin; Zeng, Heping; Wu, Jian

    2015-04-24

    We experimentally investigate the channel-resolved above-threshold double ionization (ATDI) of acetylene in the multiphoton regime using an ultraviolet femtosecond laser pulse centered at 395 nm by measuring all the ejected electrons and ions in coincidence. As compared to the sequential process, diagonal lines in the electron-electron joint energy spectrum are observed for the nonsequential ATDI owing to the correlative sharing of the absorbed multiphoton energies. We demonstrate that the distinct channel-resolved sequential and nonsequential ATDI spectra can clearly reveal the photon-induced acetylene-vinylidene isomerization via proton migration on the cation or dication states. PMID:25955049

  6. Synthesis of functional acetylene derivatives from calcium carbide.

    Science.gov (United States)

    Lin, Zhewang; Yu, Dingyi; Sum, Yin Ngai; Zhang, Yugen

    2012-04-01

    AHA Erlebnis: CaC(2), used to produce acetylene until several decades ago, is re-emerging as a cheap, sustainable resource synthesized from coal and lignocellulosic biomass. We report efficient catalytic protocols for the synthesis of functional acetylene derivatives from CaC(2) through aldehyde, alkyne, and amine (AAA) as well as alkyne, haloalkane, and amine (AHA) couplings, and in addition demonstrate its use in click and Sonogashira chemistry, showing that calcium carbide is a sustainable and cost-efficient carbon source.

  7. 76 FR 75840 - Revising Standards Referenced in the Acetylene Standard

    Science.gov (United States)

    2011-12-05

    ... language from outdated standards published by standards developing organizations (``SDO standards'') (69 FR... Association standard, CGA G-1-2003, in the Acetylene Standard. See 74 FR 40442 and 74 FR 40450, respectively... outdated standard; and impose no significant new compliance costs on employers (69 FR 68283, 68285).......

  8. 77 FR 13969 - Revising Standards Referenced in the Acetylene Standard

    Science.gov (United States)

    2012-03-08

    ... Association (GGA) acetylene standard (see 76 FR 75782). In the DFR, OSHA deleted reference to CGA G-1-2003 and... final rule published on December 5, 2011 (76 FR 75782), is effective on March 5, 2012. For the purposes....C. 553, Secretary of Labor's Order 1-2012 (77 FR 3912), and 29 CFR part 1911. Signed at...

  9. Radiation-induced crosslinking of acetylene-impregnated polyesters

    International Nuclear Information System (INIS)

    Enhanced crosslinking and reduction in chain scission are found in the amorphous regions of polycrystalline polyesters, when they are irradiated in the presence of acetylene. Increasing the chain length of the alkyl moiety is also found to decrease the extent of damaging main chain scission

  10. Acetylene Resembling Effect of Ethylene on Seed Germination: Evaluating the Effect of Acetylene Released from Calcium Carbide

    Directory of Open Access Journals (Sweden)

    Kambiz MASHAYEKHI

    2015-09-01

    Full Text Available Some vegetable seeds need a very long time to germinate. In these kinds of seeds the second phase of germination is very long. As acetylene’s chemical structure is almost similar to the gaseous hormone ethylene, its’ physiological effect on seed germination should be very similar as well. Therefore, an experiment was established in order to enhance seed germination, by treating seeds with acetylene released from interaction of calcium carbide (CaC2 with water (H2O. A simple system was designed for efficient and proper use of gaseous acetylene resulted from the two substrates interaction, which conducted the produced gas obtained inside the interaction chamber into a sealed container wherein seeds were floating in water. This experiment aimed to evaluate the effect of one concentration of acetylene with different exposure periods (between 1 to 8 hours on parsley, celery and Swees chard seeds’ germination (chosen as late germinating vegetables. The effect of acetylene on seed germination speed and percent was investigated. There were significant differences in both percent and speed of germination within the various treatments. By floating for 3, 5 and 3 hours for parsley, celery and Swiss chard respectively, the highest germination rates were observed. The highest germination speed was achieved by 5, 5 and 3 hours floating respectively for parsley, celery and Swiss chard. Based on the results obtained, the current experiment suggests that acetylene has positive effect on enhancing seed germination of named vegetables, and played the role of ethylene, its effects resembling in regard to seed germination process.

  11. Component evaluation for intersystem loss-of-coolant accidents in advanced light water reactors

    International Nuclear Information System (INIS)

    Using the methodology outlined in NUREG/CR-5603 this report evaluates (on a probabilistic basis) design rules for components in ALWRs that could be subjected to intersystem loss-of-coolant accidents (ISLOCAs). The methodology is intended for piping elements, flange connections, on-line pumps and valves, and heat exchangers. The NRC has directed that the design rules be evaluated for BWR pressures of 7.04 MPa (1025 psig), PWR pressures of 15.4 MPa (2235 psig), and 177 degrees C (350 degrees F), and has established a goal of 90% probability that system rupture will not occur during an ISLOCA event. The results of the calculations in this report show that components designed for a pressure of 0.4 of the reactor coolant system operating pressure will satisfy the NRC survival goal in most cases. Specific recommendations for component strengths for BWR and PWR applications are made in the report. A peer review panel of nationally recognized experts was selected to review and critique the initial results of this program

  12. Acetylene bubble-powered autonomous capsules: towards in situ fuel.

    Science.gov (United States)

    Moo, James Guo Sheng; Wang, Hong; Pumera, Martin

    2014-12-28

    A fuel-free autonomous self-propelled motor is illustrated. The motor is powered by the chemistry of calcium carbide and utilising water as a co-reactant, through a polymer encapsulation strategy. Expulsion of acetylene bubbles powers the capsule motor. This is an important step, going beyond the toxic hydrogen peroxide fuel used normally, to find alternative propellants for self-propelled machines.

  13. Acetylene-Accelerated Alcohol Catalytic CVD Growth of Vertically Aligned Single-Walled Carbon Nanotubes

    OpenAIRE

    R. Xiang; Einarsson, E.; Okawa, J.; Miyauchi, Y.; Maruyama, S.

    2008-01-01

    Addition of only 1% of acetylene into ethanol was found to enhance the growth rate of singlewalled carbon nanotubes (SWNTs) by up to ten times. Since acetylene is a byproduct of the thermal decomposition of ethanol, this suggests an alternative fast reaction pathway to the formation of SWNTs from ethanol via byproducts of decomposition. This accelerated growth, however, only occurred in the presence of ethanol, whereas pure acetylene at the same partial pressure resulted in negligible growth ...

  14. Inter-system biases estimation in multi-GNSS relative positioning with GPS and Galileo

    Science.gov (United States)

    Deprez, Cecile; Warnant, Rene

    2016-04-01

    The recent increase in the number of Global Navigation Satellite Systems (GNSS) opens new perspectives in the field of high precision positioning. Particularly, the European Galileo program has experienced major progress in 2015 with the launch of 6 satellites belonging to the new Full Operational Capability (FOC) generation. Associated with the ongoing GPS modernization, many more frequencies and satellites are now available. Therefore, multi-GNSS relative positioning based on GPS and Galileo overlapping frequencies should entail better accuracy and reliability in position estimations. However, the differences between satellite systems induce inter-system biases (ISBs) inside the multi-GNSS equations of observation. Once these biases estimated and removed from the model, a solution involving a unique pivot satellite for the two considered constellations can be obtained. Such an approach implies that the addition of even one single Galileo satellite to the GPS-only model will strengthen it. The combined use of L1 and L5 from GPS with E1 and E5a from Galileo in zero baseline double differences (ZB DD) based on a unique pivot satellite is employed to resolve ISBs. This model removes all the satellite- and receiver-dependant error sources by differentiating and the zero baseline configuration allows atmospheric and multipath effects elimination. An analysis of the long-term stability of ISBs is conducted on various pairs of receivers over large time spans. The possible influence of temperature variations inside the receivers over ISB values is also investigated. Our study is based on the 5 multi-GNSS receivers (2 Septentrio PolaRx4, 1 Septentrio PolaRxS and 2 Trimble NetR9) installed on the roof of our building in Liege. The estimated ISBs are then used as corrections in the multi-GNSS observation model and the resulting accuracy of multi-GNSS positioning is compared to GPS and Galileo standalone solutions.

  15. Assay of the deuterium enrichment of water via acetylene.

    Science.gov (United States)

    Previs, S F; Hazey, J W; Diraison, F; Beylot, M; David, F; Brunengraber, H

    1996-06-01

    A technique is presented for measuring the 2H enrichment of water in biological samples when this enrichment is greater than 0.2%. The sample is reacted with calcium carbide to form acetylene gas, which is determined by gas chromatography electron impact ionization mass spectrometry. Ion-molecule reactions, resulting in proton abstraction, are minimized by lowering the electron ionization energy from the usual 70 eV to 45 eV. This technique is much more rapid and economical than the classical isotope ratio mass spectrometric assay of the enrichment of hydrogen gas derived from reduction of water.

  16. Quantification and removal of some contaminating gases from acetylene used to study gas-utilizing enzymes and microorganisms.

    Science.gov (United States)

    Hyman, M R; Arp, D J

    1987-02-01

    Acetylene generated from various grades of calcium carbide and obtained from commercial- and purified-grade acetylene cylinders was shown to contain high concentrations of various contaminants. Dependent on the source of acetylene, these included, at maximal values, H(2) (0.023%), O(2) (0.779%), N(2) (3.78%), PH(3) (0.06%), CH(4) (0.073%), and acetone (1 to 10%). The concentration of the contaminants in cylinder acetylene was highly dependent on the extent of cylinder discharge. Several conventional methods used to partially purify cylinder acetylene were compared. A small-scale method for extensively purifying acetylene is described. An effect of acetylene quality on acetylene reduction assays conducted with purified nitrogenase from Azotobacter vinelandii was demonstrated.

  17. BASF and acetylene. 70 years of reppe chemistry - long-standing reliability and promising future - and now, the only natural gas based clean technology for acetylene production

    Energy Technology Data Exchange (ETDEWEB)

    Vicari, M. [BASF SE, Ludwigshafen (Germany)

    2013-11-01

    Acetylene is still an attractive intermediate synthesis component because carbon in methane from natural gas comes at a lower price than carbon in naphtha from crude oil or coal. Acetylene can be understood as a product of C-C coupling and functionalization. Beginning in the 1950s, BASF developed the partial oxidation (Pox) process, in addition to the electric arc process dating from the 1930s and the submerged flame process. The originally developed Pox process came along with severe emissions of hydrocarbons to the environment. Nowadays it is extremely important to have a clean, environmentally friendly technology. So in the 1990s a closed water-quench process was developed and built in the United States. The presentation focuses on the ways of making acetylene, the use of acetylene and BASF's closed water-quench process based on natural gas. This process will be presented including some important safety aspects. The process is available for licensing. (orig.)

  18. 46 CFR 56.50-103 - Fixed oxygen-acetylene distribution piping.

    Science.gov (United States)

    2010-10-01

    ... outlet stations. (c) Acetylene distribution piping and pipe fittings must be seamless steel. Copper..., and other equipment used with acetylene. (d) Oxygen distribution piping and pipe fittings must be seamless steel or copper. (e) When more than two cylinders are connected to a manifold, the supply...

  19. A first principles study of the acetylene-water interaction

    International Nuclear Information System (INIS)

    We present an extensive study of the stationary points on the acetylene-water (AW) ground-state potential energy surface (PES) aimed in establishing accurate energetics for the two different bonding scenarios that are considered. Those include arrangements in which water acts either as a proton acceptor from one of the acetylene hydrogen atoms or a proton donor to the triple bond. We used a hierarchy of theoretical methods to account for electron correlation [MP2 (second-order Moller-Plesset), MP4 (fourth-order Moller-Plesset), and CCSD(T) (coupled-cluster single double triple)] coupled with a series of increasing size augmented correlation consistent basis sets (aug-cc-pVnZ, n=2,3,4). We furthermore examined the effect of corrections due to basis set superposition error (BSSE). We found that those have a large effect in altering the qualitative features of the PES of the complex. They are responsible for producing a structure of higher (C2v) symmetry for the global minimum. Zero-point energy (ZPE) corrections were found to increase the stability of the C2v arrangement. For the global (water acceptor) minimum of C2v symmetry our best estimates are ΔEe=-2.87 kcal/mol (ΔE0=-2.04 kcal/mol) and a van der Waals distance of Re=2.190 Aa. The water donor arrangement lies 0.3 kcal/mol (0.5 kcal/mol including ZPE corrections) above the global minimum. The barrier for its isomerization to the global minimum is Ee=0.18 kcal/mol; however, inclusion of BSSE- and ZPE-corrections destabilize the water donor arrangement suggesting that it can readily convert to the global minimum. We therefore conclude that there exists only one minimum on the PES in accordance with previous experimental observations. To this end, vibrational averaging and to a lesser extend proper description of intermolecular interactions (BSSE) were found to have a large effect in altering the qualitative features of the ground-state PES of the acetylene-water complex. (c) 2000 American Institute of Physics

  20. Photophysics of the geminate polaron-pair state in copper phthalocyanine organic photovoltaic blends: evidence for enhanced intersystem crossing.

    Science.gov (United States)

    Snedden, Edward W; Monkman, Andrew P; Dias, Fernando B

    2013-04-01

    Geminate polaron-pair recombination directly to the triplet state of the small dye molecule copper(II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H- phthalocyanine (CuPC) and exciton trapping in CuPC domains, combine to reduce the internal quantum efficiency of free polaron formation in the bulk-heterojunction blends of CuPC doped with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor. PMID:22933249

  1. Effect of acetylene flow rate on morphology and structure of carbon nanotube thick films grown by thermal chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    CAO Zhangyi; SUN Zhuo; GUO Pingsheng; CHEN Yiwei

    2007-01-01

    Carbon nanotube (CNT) films were grown on nickel foil substrates by thermal chemical vapor deposition (CVD) with acetylene and hydrogen as the precursors. The morphology and structure of CNTs depending on the acetylene flow rate were characterized by a scanning electron microscope (SEM),a transmission electron microscope (TEM) and a Raman spectrometer,respectively.The effect of acetylene flow rate on the morphology and structure of CNT films was investigated.By increasing the acetylene flow rate from 10 to 90 sccm (standard cubic centimeter perminute),the yield and the diameter of CNTs increase.Also, the defects and amorphous phase in CNT films increase with increasing acetylene flow rate.

  2. Watching the acetylene vinylidene intramolecular reaction in real time

    CERN Document Server

    Jiang, Y H; Rudenko, A; Madjet, M E; Vendrell, O; Kurka, M; Schnorr, K; Foucar, L; Kübel, M; Herrwerth, O; Lezius, M; Kling, M F; van Tilborg, J; Belkacem, A; Ueda, K; Düsterer, S; Treusch, R; Schröter, C D; Santra, R; Ullrich, J; Moshammer, R

    2014-01-01

    It is a long-standing dream of scientists to capture the ultra-fast dynamics of molecular or chemical reactions in real time and to make a molecular movie. With free-electron lasers delivering extreme ultraviolet (XUV) light at unprecedented intensities, in combination with pump-probe schemes, it is now possible to visualize structural changes on the femtosecond time scale in photo-excited molecules. In hydrocarbons the absorption of a single photon may trigger the migration of a hydrogen atom within the molecule. Here, such a reaction was filmed in acetylene molecules (C2H2) showing a partial migration of one of the protons along the carbon backbone which is consistent with dynamics calculations on ab initio potential energy surfaces. Our approach opens attractive perspectives and potential applications for a large variety of XUV-induced ultra-fast phenomena in molecules relevant to physics, chemistry, and biology.

  3. Acetylene fuel from atmospheric CO2 on Mars

    Science.gov (United States)

    Landis, Geoffrey A.; Linne, Diane L.

    1992-01-01

    The Mars mission scenario proposed by Baker and Zubrin (1990) intended for an unmanned preliminary mission is extended to maximize the total impulse of fuel produced with a minimum mass of hydrogen from Earth. The hydrogen along with atmospheric carbon dioxide is processed into methane and oxygen by the exothermic reaction in an atmospheric processing module. Use of simple chemical reactions to produce acetylene/oxygen rocket fuel on Mars from hydrogen makes it possible to produce an amount of fuel that is nearly 100 times the mass of hydrogen brought from earth. If such a process produces the return propellant for a manned Mars mission, the required mission mass in LEO is significantly reduced over a system using all earth-derived propellants.

  4. Acetylene as Fast Food: Implications for Development of Life on Anoxic Primordial Earth and in the Outer Solar System

    Science.gov (United States)

    Oremland, Ronald S.; Voytek, Mary A.

    2008-02-01

    Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem.

  5. Acetylene as fast food: Implications for development of life on anoxic primordial earth and in the outer solar system

    Science.gov (United States)

    Oremland, R.S.; Voytek, M.A.

    2008-01-01

    Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem. ?? Mary Ann Liebert, Inc.

  6. Research on the intersystem interference between COMPASS and Galileo%COMPASS和Galileo系统间信号干扰研究

    Institute of Scientific and Technical Information of China (English)

    胡媛; 刘卫

    2012-01-01

    随着各国和地区的卫星导航系统建设.我国北斗COMPASS和欧盟Galileo系统间信号干扰已成为广泛关注的焦点。首先建立有效评价卫星导航系统间信号干扰的方法,其次分析COMPASS和Galileo系统的星座构型和信号体制参数,最后对两大系统间的民用信号间干扰进行仿真分析,结果表明COMPASS信号的引入对Galileo造成干扰,但其造成的干扰比Galileo对COMPASS的干扰小。所建立的评价方法和结果可为导航系统的信号体制设计和接收机应用提供理论参考。%With the development of satellite navigation system in many countries and regions, the intersystem interference between Chinese COMPASS and EU's Galileo has become a matter of great concern for the system providers and user communities. First, an effective evaluation method for signal interference among satellite navigation systems is established. Second, the constellation configuration and signal parameters of COMPASS and Galileo are analyzed. Finally, real simulations accounting for the interference effects between Galileo and COMPASS are carried out. All results show that COMPASS introduces intersystem interference to Galileo, but the interference effects are lower than Galileo interfered to COMPASS signals. The evaluation method and results can provide a theoretical reference for signal structure design and receiver apply.

  7. A Convenient Synthesis of Conjugated Acetylenic Ketones by Copper(l)-Catalyzed under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Alkynyl ketones are useful precursors and intermediates in synthetic organic chemistry1 and has evoked considerable interest. A number of methods for the synthesis of conjugated acetylenic ketones involve the reaction a metal acetylide with an acyl chlorides or another carboxylic acid derivative have been developed 2. Recently, the synthesis of α, β-conjugated acetylenic ketones catalyzed by Pd(Ⅱ) or by copper(Ⅰ)pd(Ⅱ) reaction of 1-alkynes and acyl chlorides have been described. The acylation of terminal alkynes by acyl chlorides in the presence of catalytic amounts copper(Ⅰ) salts leading to α, β-conjugated acetylenic ketones has also been reported. However, many of these reactions suffer from lack of high pressure (17 atm), long reaction time (30 h)and require low temperatures (-78℃). Our work involves the synthesis of conjugated acetylenic ketones via the reaction of terminal alkynes with aroyl chlorides in the presence of cuprous iodide under microwave irradiation conditions.

  8. Co-generation of acetylene and hydrogen for a carbide-based fuel system

    Energy Technology Data Exchange (ETDEWEB)

    Carreiro, Louis G.; Burke, A. Alan [Naval Undersea Warfare Center Division Newport, Code 8231, 1176 Howell Street, Newport, RI 02841 (United States); Dubois, Lily [Stonehill College, Department of Chemistry, 320 Washington Street, Easton, MA 02357 (United States)

    2010-09-15

    The co-generation of acetylene and hydrogen from the hydrolysis of calcium carbide and calcium hydride was investigated as part of a unique carbide-based fuel system intended for high-temperature fuel cells. To gain better control of this highly energetic reaction, glycerin was used to coat the reactant particles to form slurry prior to their reaction with water. This process was shown to moderate the rate of gas production, as well as to provide a means for preparing slurry that could be pumped into the reactor vessel. It was also observed that the presence of calcium hydroxide, a by-product of hydrolysis, lowered the solubility of acetylene resulting in a higher initial flow rate due to less acetylene being dissolved in solution. However, the buildup of calcium hydroxide with time inhibited the hydrolysis of both calcium carbide and calcium hydride causing the acetylene and hydrogen flow rates to decrease. (author)

  9. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene

    KAUST Repository

    Cui, X.

    2016-05-20

    The trade-off between physical adsorption capacity and selectivity of porous materials is a major barrier for efficient gas separation and purification through physisorption. We report control over pore chemistry and size in metal coordination networks with hexafluorosilicate and organic linkers for the purpose of preferential binding and orderly assembly of acetylene molecules through cooperative host-guest and/or guest-guest interactions. The specific binding sites for acetylene are validated by modeling and neutron powder diffraction studies. The energies associated with these binding interactions afford high adsorption capacity (2.1 millimoles per gram at 0.025 bar) and selectivity (39.7 to 44.8) for acetylene at ambient conditions. Their efficiency for the separation of acetylene/ethylene mixtures is demonstrated by experimental breakthrough curves (0.73 millimoles per gram from a 1/99 mixture).

  10. On the Role of Surface Modifications of Palladium Catalysts in the Selective Hydrogenation of Acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas;

    2008-01-01

    Summing Me up: DFT calculations have shown that alloying, subsurface carbon, and hydride formation, all increase the selectivity of Pd catalysts for acetylene hydrogenation by weakening the surface–adsorbate bond. A simple descriptor—the adsorption energy of a methyl group—has been used to quantify...... and compare the different effects in the adsorption of acetylene and ethylene on various transition-metal surfaces (see picture)....

  11. Effect of surface free energy of acetylene black powder on air electrode performance

    Institute of Scientific and Technical Information of China (English)

    OU Xiuqin; LIU Shuguang; LIANG Guangchuan; LI Ying; ZHI Xiaoke; HAN Bin

    2006-01-01

    The effects of acetylene black powder surface free energy on air electrode electrochemical performance and lifetime were studied. The acetylene black was immersed in 30% H2O2 at room temperature and the changes of functional groups and surface free energy were investigated by X-ray Photoelectron Spectroscopy (XPS) and powder contact angle (CA). The air electrode performance was characterized by the potential polarization curves and the lifetime was measured by constant-current discharge. It shows that, its surface free energy is the lowest when the acetylene black is immersed in H2O2 for 240 h. The polarization potential of the air electrode prepared by the pretreated acetylene black is 0.25 V(vs. Hg/HgO), 0.21 V lower than the air electrode with untreated acetylene black when the working current density is 100 mA·cm-1 . And its lifetime is over 800 h at 80 mA·cm-1 . The pretreatment of acetylene black for proper time by H2O2 is favorable for the stability of the tri-phase reaction interface of air electrode and improvement of its performance.

  12. Stability improvement of the Nieuwland catalyst in the dimerization of acetylene to monovinylacetylene

    Institute of Scientific and Technical Information of China (English)

    Jianguo Liu; Yizan Zuo; Minghan Han; Zhanwen Wang; Dezheng Wang

    2012-01-01

    In the process of dimerization of acetylene to produce monovinylacetylene (MVA),the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated.The formula of the precipitate was CuCl·2C2H2·1/5NH3,and it was presumed to be formed by the combination of NH3,C2H2 and [Cu]-acetylene π-complex,which was an intermediate in the dimerization reaction.The addition of hydrochloric acid into the catalyst can reduce the formation of precipitate,whereas excessive H+ is unfavorable to the dimerization reaction of acetylene.To balance between high acetylene conversion and low loss rate of CuCl,the optimum mass percentage of HCl in the added hydrochloric acid was determined.The result showed the optimum mass percentage of HCl decreased from 5.0% to 3.2% when the space velocity of acetylene was from 140 h-1 to 360 h-1.The result in this work also indicated the pH of the Nieuwland catalyst should be kept in the range of 5.80-5.97 during the reaction process,which was good for both catalyst life and acetylene conversion.

  13. Discovery, Development, and Commercialization of Gold Catalysts for Acetylene Hydrochlorination.

    Science.gov (United States)

    Johnston, Peter; Carthey, Nicholas; Hutchings, Graham J

    2015-11-25

    Vinyl chloride monomer (VCM) is a major chemical intermediate for the manufacture of polyvinyl chloride (PVC), which is the third most important polymer in use today. Hydrochlorination of acetylene is a major route for the production of vinyl chloride, since production of the monomer is based in regions of the world where coal is abundant. Until now, mercuric chloride supported on carbon is used as the catalyst in the commercial process, and this exhibits severe problems associated with catalyst lifetime and mercury loss. It has been known for over 30 years that gold is a superior catalyst, but it is only now that it is being commercialized. In this Perspective we discuss the use and disadvantages of the mercury catalyst and the advent of the gold catalysts for this important reaction. The nature of the active site and the possible reaction mechanism are discussed. Recent advances in the design and preparation of active gold catalysts containing ultralow levels of gold are described. In the final part, a view to the future of this chemistry will be discussed as well as the possible avenues for the commercial potential of gold catalysis. PMID:26529366

  14. VOLT-AMPERE CHARACTERISTICS OF CIS-POLY (PHENYL ACETYLENE)

    Institute of Scientific and Technical Information of China (English)

    HONG Haiping; ZHOU Shuqin; JIN Xiangfeng; QIAN Renyuan; Anita FURLANI

    1991-01-01

    The volt-ampere (I-V) characteristics of the cis-poly (phenyl acetylene) (PPA) of cis-transoidal structure has been studied in the temperature range of 253-288K. An ITO/ PPA/ Au sandwich configuration was used for the measurements. Under an applied field of less than 105V/ cm it showed ohmic behavior, while the space charge.limited current (SCLC) was observed at applied fields above 5 × 105V/ cm. In the ohmic region a conductivity of 1.37× 10-16S/ cm was obtained at room temperature with an activation energy of 0.5 eV. These data indicate that the conduction is not intrinsic one but is the result of thermal release of trapped carriers. In fact the data in the SCLC region treated according to the theory for a single Gaussian distribution of traps gave a mean trap energy of 0.48 eV with a half-width of 0.4 eV and a total density of trapping states of 5× 1016/ cm3 .

  15. Selected properties of GPS and Galileo-IOV receiver intersystem biases in multi-GNSS data processing

    International Nuclear Information System (INIS)

    Two overlapping frequencies—L1/E1 and L5/E5a—in GPS and Galileo systems support the creation of mixed double-differences in a tightly combined relative positioning model. On the other hand, a tightly combined model makes it necessary to take into account receiver intersystem bias, which is the difference in receiver hardware delays. This bias is present in both carrier-phase and pseudorange observations. Earlier research showed that using a priori knowledge of earlier-calibrated ISB to correct GNSS observations has significant impact on ambiguity resolution and, therefore, precise positioning results. In previous research concerning ISB estimation conducted by the authors, small oscillations in phase ISB time series were detected. This paper investigates this effect present in the GPS–Galileo-IOV ISB time series. In particular, ISB short-term temporal stability and its dependence on the number of Galileo satellites used in the ISB estimation was examined. In this contribution we investigate the amplitude and frequency of the detected ISB time series oscillations as well as their potential source. The presented results are based on real observational data collected on a zero baseline with the use of different sets of GNSS receivers. (paper)

  16. Ionization of large homogeneous and heterogeneous clusters generated in acetylene-Ar expansions: Cluster ion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kocisek, J.; Lengyel, J.; Farnik, M. [J. Heyrovsky Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague (Czech Republic)

    2013-03-28

    Pure acetylene and mixed Ar-acetylene clusters are formed in supersonic expansions of acetylene/argon mixtures and analysed using reflectron time-of-flight mass spectrometer with variable electron energy ionization source. Acetylene clusters composed of more than a hundred acetylene molecules are generated at the acetylene concentration of Almost-Equal-To 8%, while mixed species are produced at low concentrations ( Almost-Equal-To 0.7%). The electron energy dependence of the mass spectra revealed the ionization process mechanisms in clusters. The ionization above the threshold for acetylene molecule of 11.5 eV results in the main ionic fragment progression (C{sub 2}H{sub 2}){sub n}{sup +}. At the electron energies Greater-Than-Or-Slanted-Equal-To 21.5 eV above the CH+CH{sup +} dissociative ionization limit of acetylene the fragment ions nominally labelled as (C{sub 2}H{sub 2}){sub n}CH{sup +}, n Greater-Than-Or-Slanted-Equal-To 2, are observed. For n Less-Than-Or-Slanted-Equal-To 7 these fragments correspond to covalently bound ionic structures as suggested by the observed strong dehydrogenation [(C{sub 2}H{sub 2}){sub n}-k Multiplication-Sign H]{sup +} and [(C{sub 2}H{sub 2}){sub n}CH -k Multiplication-Sign H]{sup +}. The dehydrogenation is significantly reduced in the mixed clusters where evaporation of Ar instead of hydrogen can stabilize the nascent molecular ion. The C{sub 3}H{sub 3}{sup +} ion was previously assigned to originate from the benzene molecular ion; however, the low appearance energy of Almost-Equal-To 13.7 eV indicates that a less rigid covalently bound structure of C{sub 6}H{sub 6}{sup +} ion must also be formed upon the acetylene cluster electron ionization. The appearance energy of Ar{sub n}(C{sub 2}H{sub 2}){sup +} fragments above Almost-Equal-To 15.1 eV indicates that the argon ionization is the first step in the fragment ion production, and the appearance energy of Ar{sub n{>=}2}(C{sub 2}H{sub 2}){sub m{>=}2}{sup +} at Almost-Equal-To 13

  17. Acetylene Fermentation: Relevance to Primordial Biogeochemistry and the Search for Life in the Outer Solar System

    Science.gov (United States)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2013-12-01

    Acetylene is a highly reactive component of planet(oid)s with anoxic, methane-rich atmospheres, such as Jupiter, Saturn, Titan, and perhaps the primordial Earth. Included in this group is Enceladus, although it is not clear if the acetylene detected within its jets by Cassini was formed by photolysis of methane, from thermo-catalysis of organic matter in the orb's interior, or a fragmentation artifact of the mass spectrum of a larger hydrocarbon. Acetylene inhibits many microbial processes (e.g., methanogenesis, methane oxidation, hydrogen metabolism, denitrification) yet a number of anaerobes can use it as a carbon and energy source to support growth. The best studied is Pelobacter acetylenicus, which carries out a two-step reaction involving the enzymes acetylene hydratase and acetaldehyde dismutase. The former, a low potential W-containing enzyme, forms acetaldehyde while the latter produces ethanol and acetate. Metabolism of acetylene by mixed microbial communities (sediments and/or enrichment cultures) produces these intermediates, and when coupled with sulfate-reduction or methanogenesis respectively forms CO2 or an equal mixtures of CO2 plus CH4. It is not inconceivable that such an anaerobic, microbial food chain could exist in the waters beneath the ice cap of Enceladus, Titan, or even in the mesothermal atmospheric regions of the gas giants. Detection of the identified intermediate products of acetylene fermentation, namely acetaldehyde, ethanol, acetate and formate in the atmospheres of these planet(oid)s would constitute evidence for a microbial life signature. This evidence would be strongly reinforced if a stable carbon isotope fractionation was identified as well, whereby the products of acetylene fermentation were enriched in 12C relative to 13C (i.e., had a lighter δ13C signal) when compared to that of the starting acetylene. The most practical target to test this hypothesis would be Enceladus (if the detected acetylene is shown to be a real

  18. Acetylene fuels reductive dechlorination of TCE by Dehalococcoides/Pelobacter-containing microbial consortia

    Science.gov (United States)

    Oremland, R. S.; Mao, X.; Mahandra, C.; Baesman, S. M.; Gushgari, S.; Alvarez-Cohen, L.; Liu, T.

    2015-12-01

    Groundwater contamination by trichloroethene (TCE) poses a threat to health and leads to the generation of vinyl chloride (VC), a carcinogen. Dehalococcoides mccartyi is the only bacterium that can completely dechlorinate TCE to ethene (C2H4). Acetylene (C2H2) occurs in TCE-contaminated sites as a consequence of chemical degradation of TCE. Yet acetylene inhibits a variety of microbial processes including methanogesis and reductive dechlorination. Pelobacter acetylenicus and related species can metabolize acetylene via acetylene hydratase and acetaldehyde dismutatse thereby generating acetate and H2 as endproducts, which could serve as electron donor and carbon source for growth of D. mccartyi. We found that 1mM acetylene (aqueous) inhibits growth of D. mccartyi strain 195 on 0.3 mM TCE, but that the inhibition was removed after 12 days with the addition of an acetylene-utilizing isolate from San Francisco Bay, Pelobacter strain SFB93. TCE did not inhibit the growth of this Pelobacter at the concentrations tested (0.1-0.5 mM) and TCE was not consumed by strain SFB93. Co-cultures of strain 195 with strain SFB93 at 5% inoculation were established in 120 mL serum bottles containing 40 mL defined medium. TCE was supplied at a liquid concentration of 0.1 mM, with 0.1 mM acetylene and N2/CO2 (90:10 v/v) headspace at 34 °C. Co-cultures were subsequently transferred (5% vol/vol inoculation) to generate subcultures after 20 μmol TCE was reduced to VC and 36 μmol acetylene was depleted. Aqueous H2 ranged from 114 to 217 nM during TCE-dechlorination, and the cell yield of strain 195 was 3.7 ±0.3 × 107 cells μmol-1 Cl- released. In a D. mccartyi-containing enrichment culture (ANAS) under the same conditions as above, it was found that inhibition of dechlorination by acetylene was reversed after 19 days by adding SFB93. Thus we showed that a co-culture of Pelobacter SFB93 and D. mccartyi 195 could be maintained with C2H2 as the electron donor and carbon source while TCE

  19. Flexible band gap tuning of hexagonal boron nitride sheets interconnected by acetylenic bonds.

    Science.gov (United States)

    Zhang, Hongyu; Luo, Youhua; Feng, Xiaojuan; Zhao, Lixia; Zhang, Meng

    2015-08-21

    The energetic and electronic properties of acetylenic-bond-interconnected hexagonal boron nitride sheets (BNyne), in which the number of rows of BN hexagonal rings (denoted as BN width) between neighboring arrays of acetylenic linkages increases consecutively, have been explored using first-principles calculations. Depending on the spatial position of B/N atoms with respect to the acetylenic linkages, there are two different types of configurations. The band structure features and band gap evolutions of BNyne structures as a function of the BN width can be categorized into two families, corresponding to two distinct types of configurations. In particular, for both types of BNyne structures, the band gap variations exhibit odd-even oscillating behavior depending on the BN width, which is related to the different symmetries of acetylenic chains in the unit cell. These results suggest that the embedded linear acetylenic chains can provide more flexibility for manipulation of the atomic and electronic properties of hexagonal boron nitride. These sp-sp(2) hybrid structures might promise importantly potential applications for developing nanoscale electronic and optoelectronic devices. PMID:26194068

  20. A study on methane coupling to acetylene under the microwave plasma

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    By optimizing the microwave chemistry reactor made of the rectangular waveguide resonator,the methane conversion(the maximum 93.7%),the C2 hydrocarbon yield(the maximum 91.0%) and the acetylene yield(the maximum 88.6%) were all greatly increased under the microwave plasma.Furthermore,for the optimal reactor,the change of the methane conversion and the C2 hydrocarbon yield is little within the range of the pressures in the experiments.The C2 hydrocarbon is mainly made up of acetylene,and the selectivity for acetylene is above 90%.Energy yield and space time yield of acetylene are also high.Optical emission spectroscopy(OES) was adopted for the diagnosis of methane coupling to acetylene under microwave plasma.The excited species(CH,C2,H2,Hα) were detected in the spectra range of 300-750 nm.Based on the products and the excited species,the reaction mechanism of methane coupling under microwave plasma was investigated,using the thermodynamics and kinetics of the chemical reaction.

  1. Modeling, simulation, and optimization of a front-end system for acetylene hydrogenation reactors

    Directory of Open Access Journals (Sweden)

    Gobbo R.

    2004-01-01

    Full Text Available The modeling, simulation, and dynamic optimization of an industrial reaction system for acetylene hydrogenation are discussed in the present work. The process consists of three adiabatic fixed-bed reactors, in series, with interstage cooling. These reactors are located after the compression and the caustic scrubbing sections of an ethylene plant, characterizing a front-end system; in contrast to the tail-end system where the reactors are placed after the de-ethanizer unit. The acetylene conversion and selectivity profiles for the reactors are optimized, taking into account catalyst deactivation and process constraints. A dynamic optimal temperature profile that maximizes ethylene production and meets product specifications is obtained by controlling the feed and intercoolers temperatures. An industrial acetylene hydrogenation system is used to provide the necessary data to adjust kinetics and transport parameters and to validate the approach.

  2. Electronic properties and strain sensitivity of CVD-grown graphene with acetylene

    Science.gov (United States)

    Yang, Meng; Sasaki, Shinichirou; Ohnishi, Masato; Suzuki, Ken; Miura, Hideo

    2016-04-01

    Although many studies have shown that large-area monolayer graphene can be formed by chemical vapor deposition (CVD) using methane gas, the growth of monolayer graphene using highly reactive acetylene gas remains a big challenge. In this study, we synthesized a uniform monolayer graphene film by low-pressure CVD (LPCVD) with acetylene gas. On the base of Raman spectroscopy measurements, it was found that up to 95% of the as-grown graphene is monolayer. The electronic properties and strain sensitivity of the LPCVD-grown graphene with acetylene were also evaluated by testing the fabricated field-effect transistors (FETs) and strain sensors. The derived carrier mobility and gauge factor are 862-1150 cm2/(V·s) and 3.4, respectively, revealing the potential for high-speed FETs and strain sensor applications. We also investigated the relationship between the electronic properties and the graphene domain size.

  3. Examining the impact of acetylene on N-fixation and the active sediment microbial community

    Directory of Open Access Journals (Sweden)

    Robinson W (Wally Fulweiler

    2015-05-01

    Full Text Available Here we examined the impact of a commonly employed method used to measure nitrogen fixation, the acetylene reduction assay (ARA, on a marine sediment community. Historically, the ARA technique has been broadly employed for its ease of use, in spite of numerous known artifacts. To gauge the severity of these effects in a natural environment, we employed high-throughput sequencing to detect differences in acetylene-treated sediments versus non-treated control sediments after a seven hour incubation. Within this short time period, significant differences were seen broadly across all types of microbes identified in the sediment, implying that the changes induced by acetylene occur quickly. The results have important implications for our understanding of marine nitrogen budgets. Moreover, because the ARA technique has been widely used in terrestrial and freshwater habitats, these results may be applicable to other ecosystems.

  4. Heats of Formation of Triplet Ethylene, Ethylidene, and Acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, M.T.; Matus, M.H.; Lester Jr, W.A.; Dixon, David A.

    2007-06-28

    Heats of formation of the lowest triplet state of ethylene and the ground triplet state of ethylidene have been predicted by high level electronic structure calculations. Total atomization energies obtained from coupled-cluster CCSD(T) energies extrapolated to the complete basis set limit using correlation consistent basis sets (CBS), plus additional corrections predict the following heats of formation in kcal/mol: Delta H0f(C2H4,3A1) = 80.1 at 0 K and 78.5 at 298 K, and Delta H0f(CH3CH,3A") = 86.8 at 0 K and 85.1 at 298 K, with an error of less than +-1.0 kcal/mol. The vertical and adiabatic singlet-triplet separation energies of ethylene were calculated as Delta ES-T,vert = 104.1 and Delta ES-T,adia = 65.8 kcal/mol. These results are in excellent agreement with recent quantum Monte Carlo (DMC) values of 103.5 +- 0.3 and 66.4 +- 0.3 kcal/mol. Both sets of computational values differ from the experimental estimate of 58 +- 3 kcal/mol for the adiabatic splitting. The computed singlet-triplet gap at 0 K for acetylene is Delta ES-T,adia(C2H2) = 90.5 kcal/mol, which is in notable disagreement with the experimental value of 82.6 kcal/mol. The heat of formation of the triplet is Delta H0f(C2H2,3B2) = 145.3 kcal/mol. There is a systematic underestimation of the singlet-triplet gaps in recent photodecomposition experiments by ~;;7 to 8 kcal/mol. For vinylidene, we predict Delta H0f(H2CC,1A1) = 98.8 kcal/mol at 298 K (exptl. 100.3 +- 4.0), Delta H0f(H2CC,3B2) = 146.2 at 298 K, and an energy gap Delta ES-T-adia(H2CC) = 47.7 kcal/mol.

  5. Synthesis of Fullerene by Pyrolysis of Acetylene in Thermal HF-Plasma

    Institute of Scientific and Technical Information of China (English)

    ZHU Yanjuan; ZHANG Guofu; ZHANG Wei; LIN Tianjin; XIE Hongbo; LIU Qiuxiang; ZHANG Haiyan

    2007-01-01

    Carbon soot containing fullerene was continuously produced in volume by pyrolyzing acetylene in thermal HF-Plasma. The characteristics of the carbon soot and C60 were analyzed by thtransmission electron microscopy, UV/visible, IR and Raman spectroscopy. The results show that the main ingredients of the carbon soot with size of about 25 nm are amorphous carbon, graphite and fullerene. The fullerene yield in carbon soot is about 2.5 g·h-1. Compared with the graphite arc discharge method, the acetylene thermal plasma method is a preferential one for synthesis of fullerene.

  6. Acetylene- and Phenylacetylene-Terminated Poly(Arylene Ether Benzimidazole)s (PAEBI's)

    Science.gov (United States)

    Connell, John W.; Hergenrother, Paul M.; Smith, Joseph G., Jr.

    1994-01-01

    Polymers prepared by first synthesizing polymers terminated with hydroxy groups, then reacting them with either 4-ethynylbenzoyl chloride or 4-fluoro-4'-phenylethynylbenzophenone. Endcapped polymers thermally cured to yield materials with attractive combination of properties. Cured acetylene-and phenylacetylene-terminated PAEBI's exhibit higher glass-transition temperatures and better retention of mechanical properties at high temperatures. Cured acetylene- and phenylacetylene-terminated polymers exhibit excellent adhesion to copper foil and polyimide film. Potentially useful as adhesives, coatings, composite matrices, fibers, films, membranes, and moldings.

  7. A joint theoretical and experimental study of phenylene-acetylene molecular wires

    CERN Document Server

    Magyar, R J; Gao, Y; Wang, H L; Shreve, A P

    2004-01-01

    The excited state electronic structure of $\\pi$ conjugated phenylene-acetylene oligomers is calculated using time-dependent density functional theory (TD-DFT) approaches. The theoretical fluorescence spectra are analyzed in terms of Frank-Condon active nuclear normal modes and shown to compare well with experiment. Theoretical and experimental results for the optical absorption and emission spectra of these molecules indicate that the conjugation length can be significantly reduced by conformational rotations about the triple-bonded carbon links. This has serious implications on the electronic functionalities of polyphenylene-acetylene based molecular wires and their possible use as charge/energy conduits in nano-assemblies.

  8. Successful Commercial Testing of Novel Dry Calcium Carbide Process for Manufacture of Acetylene at Xindou Kaixing Technology Company

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The package 36 m3/h commercial test unit for manufacture of acetylene via dry CaC2 process independently developed by the Xindou Kaixing Technology Company in Chendu has been successfully demonstrated. This achievement has ap-plied for a Chinese invention patent and a patent on practi-cal new equipment. Currently the Kaixing Technology Com-pany is planning to construct a 360 m3/h dry acetylene pro-duction line at the customer site. The results of multiple feeding tests had revealed that the utilization of reaction water and gasification water was close to 100%, and the acetylene purity exceeded 98.5% with acetylene yield reach-ing over 98%. The byproduct was the powdered calcium car-bide residue with its water content lower than 8%, and its grain size less than 0.6 mm containing less than 0.04% of acetylene.

  9. Near-infrared spectra of liquid/solid acetylene under Titan relevant conditions and implications for Cassini/VIMS detections

    Science.gov (United States)

    Singh, S.; Cornet, T.; Chevrier, V. F.; Combe, J.-Ph.; McCord, T. B.; Roe, L. A.; Le Mouélic, S.; Le Menn, E.; Wasiak, F. C.

    2016-05-01

    Acetylene is thought to be abundant on Titan according to most photochemical models. While detected in the atmosphere, its likely presence at the surface still lacks physical evidence. It is thought that solid acetylene could be a major component of Titan's lakes shorelines and dry lakebed, detected as the 5 μm-bright deposits with the Cassini/VIMS instrument. Acetylene could also be present under its liquid form as dissolved solids in Titan's methane-ethane lakes, as emphasized by thermodynamics studies. This paper is devoted to the near-infrared spectroscopy study of acetylene under solid and liquid phases between 1 and 2.2 μm, synthesized in a Titan simulation chamber that is able to reproduce extreme temperature conditions. From experiments, we observed a ∼10% albedo increase between liquid acetylene at 193-188 K and solid acetylene at 93 K. Using the NIR spectroscopy technique we successfully calculated the reflectivity ratio of solid/liquid acetylene as 1.13. The second difference we observed between liquid and solid acetylene is a shift in the major absorption band detected at 1.54 μm, the shift of ∼0.01 μm occurring toward higher wavelength. In order to assess the detectability of acetylene on Titan using the Cassini/VIMS instrument, we adapted our spectra to the VIMS spectral resolution. The spectral band at 1.55 μm and a negative slope at 2.0 μm falls in the Cassini/VIMS atmospheric windows over several VIMS infrared spectels, thus Cassini/VIMS should be able to detect acetylene.

  10. 49 CFR 178.59 - Specification 8 steel cylinders with porous fillings for acetylene.

    Science.gov (United States)

    2010-10-01

    ... cylinders with porous fillings for acetylene. (a) Type and service pressure. A DOT 8 cylinder is a seamless... the cylinders must comply with the following: (1) Standard taper pipe threads are required; (2) Length may not be less than as specified for American Standard pipe threads; tapped to gauge; clean cut,...

  11. Identification of non-precious metal alloy catalysts for selective hydrogenation of acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas;

    2008-01-01

    calculations were performed that identified relations in heats of adsorption of hydrocarbon molecules and fragments on metal surfaces. This analysis not only verified the facility of known catalysts but identified nickel- zinc alloys as alternatives. Experimental studies demonstrated that these alloys...... dispersed on an oxide support were selective for acetylene hydrogenation at low pressures....

  12. Acetylenic dithiafulvene derived donor-pi-acceptor dyads: synthesis, electrochemistry and non-linear optical properties

    DEFF Research Database (Denmark)

    Nielsen, Mogens Brønsted; Petersen, Jan Conrad; Thorup, Niels;

    2005-01-01

    A selection of donor-acceptor chromophores containing the redox-active dithiafulvene unit about acetylenic and aryl scaffolds has been synthesized. The molecules were studied for their optical, redox and structural properties. Moreover, third-order non-linear optical properties were investigated ...

  13. Nine acetylenic alcohols isolated from the Okinawan marine sponge of the genus Petrosia (Strongylophora).

    NARCIS (Netherlands)

    K. Watanabe; G. Mori; K. Iguchi; M. Suzuki; R.W.M. van Soest

    2007-01-01

    Nine new acetylenic alcohols 1-9 were isolated from a marine sponge belonging to the genus Petrosia (Strongylophora). The structures were elucidated mainly based on the analysis of one-and two-dimensional NMR spectral data. To determine the position of the central double bonds in 1-8, each compound

  14. Synthesis of trifluoromethylated acetylenes via copper-catalyzed trifluoromethylation of alkynyltrifluoroborates

    KAUST Repository

    Zheng, Huidong

    2012-12-01

    A new method for the synthesis of trifluoromethylated acetylenes is developed which involves the copper-catalyzed trifluoromethylation of alkynyltrifluoroborates with an electrophilic trifluoromethylating reagent. This method offers significant advantages such as efficiency and mild and base-free reaction conditions. A plausible mechanism is proposed. © 2012 Elsevier Ltd. All rights reserved.

  15. The Electrooxidation of Tetracycline at Acetylene Black Electrode in the Presence of Sodium Dodecyl Sulfate

    Institute of Scientific and Technical Information of China (English)

    Xue Ping DANG; Cheng Guo HU; Ying Liang WEI; Sheng Shui HU

    2004-01-01

    The electrooxidation of tetracycline (TC) at acetylene black electrode has been studied in the presence of sodium dodecyl sulfate (SDS). Tetracycline (TC) exhibited very sensitive oxidation peak in this system. The peak current was proportional to TC concentration, and the detection limit was 1.2 × 10-8 mol/L. The system was used to the determination of TC in pharmaceuticals.

  16. A Safe and Easy Classroom Demonstration of the Generation of Acetylene Gas.

    Science.gov (United States)

    Cox, Marilyn Blagg; Krause, Paul

    1994-01-01

    In this demonstration of the generation and combustion of acetylene, calcium carbide and water are allowed to react in a latex examination glove. Two student volunteers perform the demonstration with instructor guidance. This safe, popular demonstration, originally intended to illustrate the alkyne family of compounds, can be used with a variety…

  17. A Convenient Synthesis of Conjugated Acetylenic Ketones by Copper(l)-Catalyzed under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    WANG; JinXian

    2001-01-01

    Alkynyl ketones are useful precursors and intermediates in synthetic organic chemistry1 and has evoked considerable interest. A number of methods for the synthesis of conjugated acetylenic ketones involve the reaction a metal acetylide with an acyl chlorides or another carboxylic acid derivative have been developed 2. Recently, the synthesis of α, β-conjugated acetylenic ketones catalyzed by Pd(Ⅱ) or by copper(Ⅰ)pd(Ⅱ) reaction of 1-alkynes and acyl chlorides have been described. The acylation of terminal alkynes by acyl chlorides in the presence of catalytic amounts copper(Ⅰ) salts leading to α, β-conjugated acetylenic ketones has also been reported. However, many of these reactions suffer from lack of high pressure (17 atm), long reaction time (30 h)and require low temperatures (-78℃). Our work involves the synthesis of conjugated acetylenic ketones via the reaction of terminal alkynes with aroyl chlorides in the presence of cuprous iodide under microwave irradiation conditions.……

  18. Facile synthesis and electrochemical performances of binder-free flexible graphene/acetylene black sandwich film

    International Nuclear Information System (INIS)

    Graphene/acetylene black sandwich film was fabricated by a simple vacuum filtration procedure using a stable complex suspension of graphene oxide (GO) and acetylene black followed by a hydroiodic acid (HI) immersion process to fully reduce the GO to graphene sheets. The self-restacking of individual graphene sheets were greatly alleviated and electric conductivity was obviously improved using the acetylene black nanoparticles as both effective spacers to expand the inter-layer interval of the individual graphene sheets during the film assembly course and highly conducting bridges to facilitate the electron/ion transfer between the upper and lower graphene sheets. The flexible graphene/acetylene black film was utilized as supercapacitor electrode without additional conductive additives, binders and current collectors, which achieved an obviously higher specific capacitance (ca. 136.6 F g−1 at 0.5 A g−1) and much better specific capacitance retention at high current densities than that of the pure graphene film electrode, indicating that such a novel sandwich film structure allows for a higher charge storage capability. More importantly, the assembled symmetric supercapacitor device displayed a satisfactory specific capacitance of 59.2 F g−1 at 0.1 A g−1, 47.6 F g−1 at 0.5 A g−1 and 42.8 F g−1 at 1 A g−1, and only negligible 4.05% capacitance degradation have been found after 1000 continuous charge-discharge cycles at 0.5 A g−1, revealing outstanding rate capability, excellent electrochemical reversibility and long-term cyclability. These results proved that such a flexible and highly conductive graphene/acetylene black film can be promising electroactive materials in the development of advanced electrochemical energy storage devices

  19. Influence of soil composition in the determination of chromium by atomic absorption spectrometry with flame air / acetylene

    International Nuclear Information System (INIS)

    The Air-acetylene Flame Atomic Absorption determination of chromium is a complex task, being strongly influenced by sample composition and instrumental conditions. The objective of this work was to study the influence of Al, Ca, Fe, K, Mg, and Na on the absorption of chromium in the air-acetylene flame, both separately and combined in solution, when acetylene flow and burner height vary. Dissolutions of the mixtures simulated the composition of four soils from the Quibu River Basin in Havana, Cuba. Chromium absorption first increased and then decreased with increment of acetylene flow for shorter burner heights (∼ 2-4 mm); while a continuous increase was observed for larger heights (> 4 mm). This behavior was the same in the presence and absence of interfering chemical element, mentioned above. On the other hand, the dependence of the magnitude of the interference with acetylene flow and burner height was complex and dependent on the interfering element, particularly at larger heights where the behavior of Al was remarkably different. The interference of the four mixtures of Al, Ca, K, Fe, Mg and Na decreased in comparison to individual interfering effects and was less dependent on acetylene flow and burner height. Finally, a significant reduction of interference on chromium determination in soil samples was achieved by an adequate selection of acetylene flow and burner height

  20. Donor-Acceptor Chromophores based on Acetylenic Scaffolds and Indenofluorenes

    DEFF Research Database (Denmark)

    Christensen, Mikkel Andreas

    -valence salt). [BILLEDE UDELADT] In the third chapter the reactivity of chloroalkynes is explored. A number of chloroalkynes is prepared and subjected to palladium-catalyzed cross coupling with a terminal alkyne. The chloroalkynes turned out to couple very well using the same conditions as for the Sonogashira...... cross-coupling. The reactivity of chloroalkynes was compared to that of Sonogashira substrates and the chloroalkynes turned out to react as fast as an aryl iodide. Some of the couplings gave reductive homo-coupling of the chloroalkyne as a byproducts. This was avoided by using a large copper...

  1. Acetylene hydratase of Pelobacter acetylenicus. Molecular and spectroscopic properties of the tungsten iron-sulfur enzyme.

    Science.gov (United States)

    Meckenstock, R U; Krieger, R; Ensign, S; Kroneck, P M; Schink, B

    1999-08-01

    Acetylene hydratase of Pelobacter acetylenicus is a tungsten iron-sulfur protein involved in the fermentation of acetylene to ethanol and acetate. Expression of the enzyme was increased 10-fold by feeding a 50-L batch culture continuously with 104 Pa acetylene at pH 6.8-7.0. Acetylene hydratase was purified to homogeneity by a three-step procedure in either the absence or presence of dioxygen. The enzyme was a monomer with a molecular mass of 73 kDa (SDS/PAGE) or 83 kDa (matrix-assisted laser-desorption ionization MS) and contained 0.5 +/- 0.1 W (inductively coupled plasma/MS) and 1.3 +/- 0.1 molybdopterin-guanine dinucleotide per mol. Selenium was absent. EPR spectra (enzyme as isolated, under air) showed a signal typical of a [3Fe-4S] cluster with gav = 2.01, at 10 K. In enzyme prepared under N2/H2, this signal was absent and reaction with dithionite led to a rhombic signal with gz = 2.048, gy = 1.939 and gx = 1.920 indicative of a low-potential ferredoxin-type [4Fe-4S] cluster. Upon oxidation with hexacyanoferrate(III), a new signal appeared with gx = 2.007, gy = 2.019 and gz = 2.048 (gav = 2.022), which disappeared after further oxidation. The signal was still visible at 150 K and was tentatively assigned to a W(V) center. The iron-sulfur center of acetylene hydratase (prepared under N2/H2) gave a midpoint redox potential of -410 +/- 20 mV in a spectrophotometric titration with dithionite. Enzyme activity depended on the redox potential of the solution, with 50% of maximum activity at -340 +/- 20 mV. The presence of a pterin-guanine dinucleotide cofactor differentiates acetylene hydratase from the aldehyde ferredoxin oxidoreductase-type enzymes which have a pterin mononucleotide cofactor. PMID:10447686

  2. Reactivity of free radical intermediates that form spontaneously during molecular chlorine action on acetylene and vinyl monomers at low temperatures

    International Nuclear Information System (INIS)

    In this study ESR, UV, VIS and IR spectroscopy, chromatography, calorimetry, and elemental analysis were employed to show the spontaneous formation of free radicals under low-temperature action of molecular chlorine on acetylene monomer p-diethynylbenzene, and vinyl monomer acrylamide. These radicals are able to initiate chain reaction of polymerization of monomers at low temperatures. This reaction results in a completely soluble polymer with a yield of 25 %, while an insoluble cross-linked polymer has been obtained during polymerization of p-diethynylbenzene initiated by other means. For example, under radiolysis by 1000 kGy the soluble fraction of obtained polymer was ∼ 1% while the overall yield was ∼ 10%. p-Diethynylbenzene polymerizes at temperatures close to chlorine melting (170 K). Polymerization of acrylamide takes place in the temperature range of 180-210 K with an yield of polymer ∼ 10%. The low-temperature chlorination of a 20%-solution of acrylamide in glycerol enables a twofold increase of the polymer yield, and a tenfold decrease of the chlorine content in it.

  3. Numerical Study on the Acetylene Concentration in the Hydrogen-Carbon System in a Hydrogen Plasma Torch

    Institute of Scientific and Technical Information of China (English)

    CHEN Longwei; SHEN Jie; SHU Xingsheng; FANG Shidong; ZHANG Lipeng; MENG Yuedong

    2009-01-01

    Effects of the hydrogen/carbon mole ratio and pyrolysis gas pressure on the acetylene concentration in the hydrogen-carbon system in a plasma torch were numerically calculated by using the chemical thermodynamic equilibrium method of Gibbs free energy. The calculated results indicate that the hydrogen concentration and the pyrolysis gas pressure play crucial roles in acetylene formation. Appropriately abundant hydrogen, with a mole ratio of hydrogen to carbon about 1 or 2, and a relatively high pyrolysis gas pressure can enhance the acetylene concentration. In the experiment, a compromised project consisting of an appropriate hydrogen flow rate and a feasible high pyrolysis gas pressure needs to be carried out to increase the acetylene concentration from coal pyrolysis in the hydrogen plasma torch.

  4. Isotope effect in normal-to-local transition of acetylene bending modes

    International Nuclear Information System (INIS)

    The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helps to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement

  5. Theoretical and Experimental Evidence of Hydrogen Migration rather than Isomerization in the Acetylene Dication

    Science.gov (United States)

    Liekhus-Schmaltz, Chelsea; Li, Zheng; Petrovic, Vladimir; Martinez, Todd; Bucksbaum, Phil; AMO75113 Collaboration

    2016-05-01

    Theoretical calculations and experimental results in the acetylene dication have long agreed that isomerization after x-ray excitation occurs in the first singlet state, where the carbon-carbon bond lives long enough for isomerization to complete. These same calculations predict that a large barrier to isomerization exists that would cause isomerization to occur in about a picosecond, while there is some evidence for ultrafast isomerization in under 100 fs. However, new ab initio calculations of the acetylene dication reveal that ultrafast isomerization after x-ray excitation is unlikely. In this talk, we present evidence that signatures of hydrogen migration observed in recent time resolved LCLS data are mostly due to hydrogen migration in an excited state which dissociates too quickly for isomerization to complete. This material is based upon work supported by the National Science Foundation under Grant No. PHY-0649578.

  6. Groundwater remediation engineering--Study on the flow distribution of air sparging using acetylene

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yan-mei; ZHANG Ying; HUANG Guo-qiang; JIANG Bin; LI Xin-gang

    2005-01-01

    Air sparging(AS) is an emerging method to remove VOCs from saturated soils and groundwater. Air sparging performance highly depends on the air distribution resulting in the aquifer. In order to study gas flow characterization, a two-dimensional experimental chamber was designed and installed. In addition, the method by using acetylene as the tracer to directly image the gas distribution results of AS process has been put forward. Experiments were performed with different injected gas flow rates. The gas flow patterns were found to depend significantly on the injected gas flow rate, and the characterization of gas flow distributions in porous media was very different from the acetylene tracing study. Lower and higher gas flow rates generally yield more irregular in shape and less effective gas distributions.

  7. Carbide sludge management in acetylene producing plants by using vacuum filtration.

    Science.gov (United States)

    Ramasamy, Palanisamy; Periathamby, Agamuthu; Ibrahim, Shaliza

    2002-12-01

    Carbide sludge (10.4-11.5 tonnes day(-1)) is generated from the reaction of calcium carbide (900 kg) and water (6,000 L) in the production of acetylene (2,400 m3), in three selected acetylene manufacturing plants. The sludge (of pH 12.2 and containing Cu, Pb, Fe, Mn, Ni and Zn ions whose concentrations exceed the Department of Environment limits for industrial wastewater) was treated by vacuum filtration as a substitute for the ponding system, which is environmentally less acceptable. A similar system by flocculation was also developed. The filtration system represents an improvement over the ponding method, as shown by a pH of 7 for the clear filtrate; the solid cake, which contains 98% of the metals, can be conveniently disposed at an integrated scheduled waste treatment centre.

  8. Epigenetic modifier-induced biosynthesis of novel acetylenic sterols from Cladosporium colocasiae.

    Science.gov (United States)

    Liu, Dong-Ze; Liang, Bo-Wen; Li, Xiao-Fei; Yu, Zhi-Yuan

    2014-09-01

    The addition of an HDAC inhibitor, suberoylanilide hydroxamic acid (SBHA), to the culture medium of Cladosporium colocasiae, dramatically altered its metabolic profiles. Analysis of the culture broth extract led to the isolation of two new acetylenic sterols (1-2). The isolated compounds were further evaluated for their cytotoxic and antibacterial activities. Compound 1 showed activity against Bacillus subtilis, affording a zone of inhibition of 12mm at 100μg/disk. However, none of them showed noticeable growth inhibitory effects.

  9. Rotation of a single acetylene molecule on Cu(001) by tunneling electrons in STM

    OpenAIRE

    Shchadilova, Yulia E.; Tikhodeev, Sergei G.; Paulsson, Magnus; Ueba, Hiromu

    2013-01-01

    We study the elementary processes behind one of the pioneering works on STM controlled reactions of single molecules [Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)]. Using the Keldysh-Green function approach for the vibrational generation rate in combination with DFT calculations to obtain realistic parameters we reproduce the experimental rotation rate of an acetylene molecule on a Cu(100) surface as a function of bias voltage and tunneling current. This combined approach allows us to ident...

  10. Dual fuel operation of used transformer oil with acetylene in a DI diesel engine

    International Nuclear Information System (INIS)

    Highlights: • Utilisation of Used transformer oil (UTO) as a fuel in a diesel engine. • UTO with acetylene in a diesel engine, on a dual fuel mode technique. • Analysis of combustion characteristics of the diesel engine. • Analysis of performance and emission characteristics of the diesel engine. - Abstract: Used transformer oil (UTO) is a waste oil obtained from power transformers and welding transformers. It possesses considerable heating value and properties similar to diesel fuel. A preliminary investigation on the utilization of the UTO in a single cylinder, four stroke small powered direct injection (DI) diesel engine revealed that at an optimum injection timing of 20°CA the engine exhibited lower nitric oxide (NO) and higher smoke emissions, compared to that of diesel operation. In order to improve the performance and reduce the smoke emission, a dual fuel operation was attempted in the present investigation. Acetylene was inducted as a primary fuel at four different flow rates viz 132 g/h, 198 g/h, 264 g/h and 330 g/h along with the air, to study the combustion, performance and emission behavior of a four-stroke, 4.4 kW diesel engine, while the UTO was injected as pilot fuel with the optimized injection timing. The experimental results were compared with diesel-acetylene dual fuel operation in the same engine. Acetylene aspiration reduced the ignition delay and maximum cylinder pressure by about 3°CA, and 25% respectively at full load in comparison with the sole UTO operation. Higher thermal efficiency and lower exhaust gas were also observed at full load. Smoke was reduced by about 13.7%, in comparison with the UTO operation at full load

  11. Phase-vanishing method with acetylene evolution and its utilization in several organic syntheses.

    Science.gov (United States)

    Matake, Ryosuke; Niwa, Yuki; Matsubara, Hiroshi

    2015-05-15

    A novel quadraphasic phase-vanishing system in which acetylene is evolved from calcium carbide and directly applied in situ to the Sonogashira coupling reaction was developed. This method, which provides a safe, convenient, and one-pot means to utilize gaseous reagents without special equipment, was also applied to a Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and a three-component aldehyde-alkyne-amine (A(3)) coupling reaction with excellent results.

  12. Melamine Modification of Spherical Activated Carbon and Its Effects on Acetylene Hydrochlorination

    Institute of Scientific and Technical Information of China (English)

    HAN Weijie; WANG Xugen; ZHU Mingyuan; ZHANG Haiyang; CHEN Kun; WANG Qinqin; LI Xiaoyan; DAI Bin

    2014-01-01

    Commercial spherical activated carbon (SAC) was modified by impregnation to enhance the catalytic properties of SAC in acetylene hydrochlorination through melamine modification. Different modification conditions for SAC with nitrogen were compared by changing the SAC-Melamine ratios. The effect of carbonization temperature on the modification was also investigated. Surface chemistry and adsorption properties of the modified and unmodified SACs were studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), elementary analysis, BET, and temperature-programmed desorption (TPD). Moreover, the catalytic properties of SAC in acetylene hydrochlorination under differently modified conditions were also investigated. Elemental analysis showed that the nitrogen content of the modified SAC was greatly improved. XPS revealed that nitrogen mainly exists in Pyrrole nitrogen and Pyridine nitrogen. TPD showed that desorption of C2H2 was changed by modification. The conversion rate of acetylene was up to 70%under the following reaction conditions:temperature, 150℃;C2H2 hourly space velocity (GHSV), 36 h-1;feed volume ratio V (HCl)/V (C2H2) = 1.15. The catalytic properties of SAC were improved significantly via melamine modification.

  13. Molecular movie for the isomerization of acetylene dication made by time resolved Coulomb imaging

    CERN Document Server

    Li, Zheng; Curchod, Basile; Liekhus-Schmaltz, Chelsea; Vendrell, Oriol; Medvedev, Nikita; Pabst, Stefan; Cryan, James; Osipov, Timur; Bucksbaum, Phil; Martinez, Todd

    2016-01-01

    Experimental evidence has pointed toward the existence of ultrafast proton migration and isomerization as a key process for acetylene and its ions, however the actual mechanism for ultrafast isomerization of the acetylene [HCCH]2+ to vinylidene [H2CC]2+ dication remains nebulous. Theoretical studies show a high potential barrier of over 2 eV [J. Chem. Phys. 123, 134320 (2005)] for the isomerization pathways on the low lying dicationic states, the corresponding isomerization should take picoseconds. However a recent experiment with femtosecond X-ray free electron laser (XFEL) [Nature Commun. 6, 8199 (2015)] suggests signature of isomerization proceeding on a sub-100 femtosecond time scale. We present here a complete theoretical study of the dynamics of acetylene dication from Auger decay induced by X-ray photoionizing the carbon K shell. We find a pathway from high lying dissociative dicationic states, which can lead to the sub-100fs isomerization with assistance of the non-Born-Oppenheimer effect. Moreover, o...

  14. High-resolution Absorption Spectra of Acetylene in 142.8-152.3 nm

    Institute of Scientific and Technical Information of China (English)

    Ya-hua Hu; Chen Zhen; Jing-hua Dai; Xiao-guo Zhou; Shi-lin Liu

    2008-01-01

    The absorption spectra of acetylene molecules was measured under jet-cooled conditions in the wavelength range of 142.8-152.3 nm, with a tunable and highly resolved vacuum ultraviolet (VUV) laser generated by two-photon resonant four wave difference frequency mixing processes. Due to the sufficient vibrational and rotational cooling effect of the molecular beam and the higher resolution VUV laser, the observed absorption spectra exhibit more distinct spectral features than the previous works measured at room temperature. The major three vibrational bands are assigned as a C-C symmetry stretching vibrational progress (v2=0-2) of the C~Ⅱu state of acetylene. The observed shoulder peak at 148.2 nm is assigned to the first overtone band of the trans-bending mode v4 of the C~Ⅱu state of acetylene. Additionally, the two components, 42 (μ1 Ⅱu) and 42(K1Ⅱu), are suggested to exhibit in the present absorption spectra, due to their Penner-Teller effect and transition selection rule. All band origins and bandwidths are obtained subsequently, and it is found that bandwidths are broadened and lifetimes decrease gradually with the excitation of vibration.

  15. Dehalogenative Homocoupling of Terminal Alkynyl Bromides on Au(111): Incorporation of Acetylenic Scaffolding into Surface Nanostructures.

    Science.gov (United States)

    Sun, Qiang; Cai, Liangliang; Ma, Honghong; Yuan, Chunxue; Xu, Wei

    2016-07-26

    On-surface C-C coupling reactions of molecular precursors with alkynyl functional groups demonstrate great potential for the controllable fabrication of low-dimensional carbon nanostructures/nanomaterials, such as carbyne, graphyne, and graphdiyne, which demand the incorporation of highly active sp-hybridized carbons. Recently, through a dehydrogenative homocoupling reaction of alkynes, the possibility was presented to fabricate surface nanostructures involving acetylenic linkages, while problems lie in the fact that different byproducts are inevitably formed when triggering the reactions at elevated temperatures. In this work, by delicately designing the molecular precursors with terminal alkynyl bromide, we introduce the dehalogenative homocoupling reactions on the surface. As a result, we successfully achieve the formation of dimer structures, one-dimensional molecular wires and two-dimensional molecular networks with acetylenic scaffoldings on an inert Au(111) surface, where the unexpected C-Au-C organometallic intermediates are also observed. This study further supplements the database of on-surface dehalogenative C-C coupling reactions, and more importantly, it provides us an alternative efficient way for incorporating the acetylenic scaffolding into low-dimensional surface nanostructures. PMID:27326451

  16. Transition probabilities for the 3s2 3p(2P0)-3s3p2(4P) intersystem lines of Si II

    Science.gov (United States)

    Calamai, Anthony G.; Smith, Peter L.; Bergeson, S. D.

    1993-01-01

    Intensity ratios of lines of the spin-changing 'intersystem' multiplet of S II (4P yields 2P0) at 234 nm have been used to determine electron densities and temperatures in a variety of astrophysical environments. However, the accuracy of these diagnostic calculations have been limited by uncertainties associated with the available atomic data. We report the first laboratory measurement, using an ion-trapping technique, of the radiative lifetimes of the three metastable levels of the 3s3p2 4P term of Si II. Our results are 104 +/- 16, 406 +/- 33, and 811 +/- 77 micro-s for lifetimes of the J = 1/2, 5/2, and 3/2 levels, respectively. A-values were derived from our lifetimes by use of measured branching fractions. Our A-values, which differ from calculated values by 30 percent or more, should give better agreement between modeled and observed Si II line ratios.

  17. Acetylene from the co-pyrolysis of biomass and waste tires or coal in the H{sub 2}/Ar plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bao, W.; Cao, Q.; Lv, Y.; Chang, L. [Taiyuan University of Technology, Taiyuan (China)

    2008-07-01

    Acetylene from carbon-containing materials via plasma pyrolysis is not only simple but also environmentally friendly. In this article, the acetylene produced from co-pyrolyzing biomass with waste tire or coal under the conditions of H{sub 2}/Ar DC arc plasma jet was investigated. The experimental results showed that the co-pyrolysis of mixture with biomass and waste tire or coal can improve largely the acetylene relative volume fraction (RVF) in gaseous products and the corresponding yield of acetylene. The change trends for the acetylene yield of plasma pyrolysis from mixture with raw sample properties were the same as relevant RVF. But the yield change trend with feeding rate is different from its RVF. The effects of the feeding rate of raw materials and the electric current of plasmatron on acetylene formation are also discussed.

  18. Evidence for alkali metal induced intermolecular acetylenic hydrogen atom transfer between hydrogen-bonded alkyne complexes in solid argon

    International Nuclear Information System (INIS)

    Condensation of acetylene, propyne, and 2-butyne/acetylene mixtures with heavy alkali metal atoms (Na, K, Cs) in an argon matrix at 15 K has led to the appearance of infrared absorptions due to ethylene, propylene, and trans-2-butene, respectively. These results stand in sharp contrast with the products obtained with lithium. Isotopic studies have shown that ethylene formation involved three different acetylene molecules and evidenced a difference in the product yield with hydrogen vs. deuterium as well as a preference for trans- vs. cis-C2H2D2 formation, which is discussed and rationalized by differences in the zero point energies for the different mixed deuterium isotopes of the intermediate vinyl radical. This trend is amplified by methyl substitution. Spectroscopic evidence was found in these experiments for cesium acetylide (Cs+C2H-) and a cesium-acetylene π complex, which are involved in the intermolecular acetylenic hydrogen atom transfer process. 26 references, 3 figures, 2 tables

  19. The 2Πg shape resonance of acetylene anion: an investigation with the RAC method

    Science.gov (United States)

    Čurík, Roman; Paidarová, Ivana; Horáček, Jiří

    2016-07-01

    Recently developed method of regularized analytic continuation (RAC) is applied to determination of the 2Πg resonance of acetylene anion. The method is based on continuation of the electron affinities calculated for the anion in presence of an external perturbation field. Its independence on the correlation treatment of the many-electron system allows application of accurate coupled-clusters methods for electronic structure calculations utilized in determination of the resonance position and width. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  20. Photodissociation of acetylene: Determination of D sup 0 sub 0 (HCC--H) by photofragment imaging

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, D.P.; Buntine, M.A.; Chandler, D.W. (Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551 (USA))

    1990-11-01

    Acetylene cooled in a He supersonic expansion is photodissociated by excitation in the 201--216 nm region of the {ital {tilde A}} {sup 1}{ital A}{sub {ital u}} {minus}{ital {tilde X}} {sup 1}{Sigma}{sup +}{sub {ital g}} transition. Subsequent ionization of the H-atom fragments by 2+1 (243 nm) REMPI, and mass-selected ion imaging allows analysis of the velocity distribution of H-atoms from the HCCH {sup {ital h}{nu}}{sub {r arrow}} C{sub 2}H+{ital H} process. Measurement of the maximum velocity for H atoms from this channel produced by photodissociation of acetylene through the {ital {tilde A}} {sup 1}{ital A}{sub {ital u}} {minus}{ital {tilde X}} {sup 1}{Sigma}{sup +}{sub {ital g}} {ital V}{sup 7}{sub 0}{ital K}{sup 1}{sub 0}, 1{sup 1}{sub 0}{ital V}{sup 4}{sub 0}{ital K}{sup 1}{sub 0}, 2{sup 1}{sub 0}{ital V}{sup 5}{sub 0}{ital K}{sup 1}{sub 0} and {ital V}{sup 5}{sub 0}{ital K}{sup 1}{sub 0} vibronic transitions gives a value for {ital D}{sup 0}{sub 0} (HCC--H) of 131{plus minus}1 kcal/mol. Other channels producing hydrogen atoms (including HC{sub 2} {sup {ital h}{nu}}{sub {r arrow}} {ital C}{sub 2}+{ital H} and HCCH{sup {ital h}{nu}}{sub {r arrow}} HCCH{sup +} {sup {ital h}{nu}}{sub {r arrow}} C{sub 2}H{sup +}+{ital H}) are detected at all photon fluxes used. These multiphoton channels produce hydrogen atoms with higher translational energy and therefore obscure measurement of the maximum velocity of H atoms produced by single-photon dissociation of acetylene. Reduction of photon flux by more than two orders of magnitude to {similar to}5{times}10{sup 6} J/cm{sup 2} gives a background, multiphoton, H-atom intensity of {le}7% of the peak primary dissociation intensity. Because this multiphoton background limits the detectability of fast H atoms from single-photon dissociation of acetylene, the dissociation energy reported here is an upper limit.

  1. Mechanisms of π-bond oxidation by cytochrome p-450: acetylenes as probes

    International Nuclear Information System (INIS)

    Phenylacetylene and biphenylacetylene are oxidized by microsomal and purified P-450 to the corresponding arylacetic acids. During this transformation, the acetylenic hydrogen undergoes a 1,2 shift which causes a kinetic isotope effect of 1.8 on the overall enzymatic rate. The same products and kinetic isotope effects are observed when the arylacetylenes are oxidized by m-chloroperbenzoic acid. Suicide inactivation of P-450 by the arylacetylenes, which occurs simultaneously with metabolite formation, is insensitive to isotopic substitution so the partition ratio changes from 26 for phenylacetylene of 14 for [1-2H] phenylacetylene

  2. Effect of Varying Inert Gas and Acetylene Concentration on the Synthesis of Carbon Nanotubes.

    Science.gov (United States)

    Afrin, Rahat; Abbas, Syed Mustansar; Shah, Nazar Abbas; Mustafa, Muhammad Farooq; Ali, Zulfiqar; Ahmad, Nisar

    2016-03-01

    The multiwalled carbon nanotubes (MWCNTs) with small diameter and high purity were achieved by chemical vapor deposition technique using silicon substrate. The introduction of specific concentration of inert gas with hydrocarbon played a key role in controlling morphology and diameter of MWCNTs. Nickel mixed ferrite nanoparticles were used as a catalyst for the growth of MWCNTs. Growth parameters like concentration of hydrocarbon source and inert gas flow, composition of catalyst particles and growth temperature were studied. In this work smaller diameter and twisted MWCNTs were formed by dilution of acetylene with argon gas. Electrical properties suggest a semimetallic behavior of synthesized MWCNTs.

  3. Nitrogen/argon diluted acetylene and ethylene blue flames under infrared CO2 laser irradiation

    OpenAIRE

    Pikhitsa, Peter V.; Daegyu Kim; Mansoo Choi

    2011-01-01

    We investigated changes in emission spectra from nitrogen/argon diluted laminar diffusion acetylene and ethylene blue flames irradiated by a powerful cw infrared CO2 laser. The changes in the radical emission bands can be interpreted as an indication of laser-induced decomposition of ethylene (for laser absorbing C2H4 fuel) and of laser-absorbing intermediates (for non-absorbing C2H2 fuel). The results indicate that released active hydrogen plays an important role in addition/abstraction reac...

  4. Ab-initio simulation of the ionization and fragmentation of acetylene by strong femtosecond laser pulses

    International Nuclear Information System (INIS)

    The electron and nuclear dynamics of acetylene when interacting with strong short laser pulses has been simulated in the framework of real-space Time Dependent Density Functional Theory (TDDFT) and molecular dynamics. The stretching and dissociation of individual bonds are reported, and are shown to depend on the laser field intensity and orientation relative to the laser polarization. The ionization dynamics, including ionization from individual Kohn-Sham orbitals, is also reported. The orbital ionization dynamics are shown to vary with an increase in the intensity of the laser field

  5. Nitrogen/argon diluted acetylene and ethylene blue flames under infrared CO2 laser irradiation

    Directory of Open Access Journals (Sweden)

    Peter V. Pikhitsa

    2011-09-01

    Full Text Available We investigated changes in emission spectra from nitrogen/argon diluted laminar diffusion acetylene and ethylene blue flames irradiated by a powerful cw infrared CO2 laser. The changes in the radical emission bands can be interpreted as an indication of laser-induced decomposition of ethylene (for laser absorbing C2H4 fuel and of laser-absorbing intermediates (for non-absorbing C2H2 fuel. The results indicate that released active hydrogen plays an important role in addition/abstraction reactions without any participation of oxygen.

  6. Synthesis of (iso)quinoline, (iso)coumarin and (iso)chromene derivatives from acetylene compounds

    Science.gov (United States)

    Ryabukhin, D. S.; Vasilyev, A. V.

    2016-06-01

    Published data on the methods of synthesis of quinoline, isoquinoline, coumarin, isocoumarin, chromene and isochromene derivatives from acetylene compounds are summarized. The reactions catalyzed by metal complexes (Pd, Pt, Ru, Rh, Au, Ag, Ni, Cu, etc.) and transformations induced by various electrophilic reagents (Brynsted and Lewis acids) are considered. Moieties of the mentioned heterocyclic systems are present in many biologically active natural products and pharmaceutical agents. Besides, derivatives of these heterocycles are used in the manufacture of catalysts, dyes, perfumery and cosmetic products, corrosion inhibitors and so on. The bibliography includes 211 references.

  7. Frequency stabilization in FBG external cavity semiconductor laser based on acetylene absorption method

    Institute of Scientific and Technical Information of China (English)

    Li Zhi-quan; Su Feng-yan; Kang Li-li

    2008-01-01

    A frequency-stabilized 1.53 μm FBG external-cavity semiconductor laser by using acetylene absorption is presented and its basic principles are introduced. Graded refractive index fiber and pigtailed fiber are used in the absorption air chamber to enhance the coupling stability. The impact of the background power is eliminated by using the third-harmonic modelocking technique. A lock-in amplifier is utilized to ensure that the output laser wavelength is locked at the C2H2 absorption line of 1530.37 nm. The frequency stability reaches 10-8 within 24 h.

  8. Denitrification in Low pH Spodosols and Peats Determined with the Acetylene Inhibition Method

    OpenAIRE

    1980-01-01

    Potential denitrification rates were determined for predominantly acid (pH ≥ 3.6) horizons of forestal, miry, and agricultural soils from 22 locations in southern Finland. The acetylene inhibition method was used with nitrate-amended water-logged soils incubated in an N2 atmosphere containing 2.5 or 5% C2H2. Complete inhibition of the reduction of N2O to N2 was observed in 99.3% of the samples. The denitrification rates varied from 0.12 to 53.8 μg of N·cm-3·day-1. Correlation between denitrif...

  9. Cycloisomerization of acetylenic oximes and hydrazones under gold catalysis: Synthesis and cytotoxic evaluation of isoxazoles and pyrazoles

    Indian Academy of Sciences (India)

    J C Jeyaveeran; Chandrasekar Praveen; Y Arun; A A M Prince; P T Perumal

    2016-01-01

    The synthesis of substituted isoxazoles and pyrazoles through a general cycloisomerization methodology has been reported. The capability of gold(III) chloride to promote cycloisomerization of both , -acetylenic oximes and , -acetylenic hydrazones is the centrepiece of the strategy. A range of acetylenic precursors were investigated to afford 28 examples of the products with good to excellent chemical yields. Selected compounds were screened for their cytotoxic potential towards COLO320 cancer cell lines. The IC50 values of the tested compounds were in the micromolar range, with the best compound, 5-(6-Methoxy-naphthalen-2-yl)-3-phenyl-isoxazole (3h) displaying an IC50 of 38.9 M. For this compound, the crystal structure in complex with Aurora-A kinase was obtained which revealed details of its binding mode within the active site with a free energy of binding -9.54 kcal/mol.

  10. Characterization of magnetically confined low-pressure plasmas produced by an electromagnetic field in argon-acetylene mixtures

    Science.gov (United States)

    Makdessi, G. Al; Margot, J.; Clergereaux, R.

    2016-10-01

    Dust particles formation was investigated in magnetically confined low-pressure plasma produced in argon-acetylene mixtures. The plasma characteristics were measured in order to identify the species involved in the dust particles formation. Their dependence on the operating conditions including magnetic field intensity, acetylene fraction in the gas mixture and operating pressure was examined. In contrast with noble gases, in the presence of acetylene, the electron temperature increases with the magnetic field intensity, indicating additional charged particles losses in the plasma. Indeed, in these conditions, larger hydrocarbon ions are produced leading to the formation of dust particles in the plasma volume. The observed dependence of positive ion mass distribution and density and relative negative ion density on the operating parameters suggests that the dust particles are formed through different pathways, where negative and positive ions are both involved in the nucleation.

  11. 2-methyl-3-butyn-2-ol as an acetylene precursor in the Mannich reaction. A new synthesis of suicide inactivators of monoamine oxidase

    International Nuclear Information System (INIS)

    A two-step reaction process is reported for the synthesis of 11C, 13C, or 14C-labelled propargylamines in moderate yields. The propargylamines were prepared by a modified Mannich scheme without the use of acetylene. The reaction scheme involved the use of 2-methyl-3-butyn-2-ol followed by KOH-catalyzed elimination of acetone from the acetylenic carbinols

  12. A CATALYST, A PROCESS FOR SELECTIVE HYDROGENATION OF ACETYLENE TO ETHYLENE AND A METHOD FOR THE MANUFACTURE OF THE CATALYST

    DEFF Research Database (Denmark)

    2009-01-01

    A catalyst comprising a mixture of metal A selected from the group of Fe, Co and Ni and metal B selected from the group of Zn and Ga, and a support material, wherein the two metals are present in an intermetallic composition; A method for the manufacture of the catalyst; and the use of above...... mentioned catalyst for the selective hydrogenation of acetylene to ethylene in a gas mixture comprising acetylenic impurities and hydrogen and one or more of, ethylene and carbon monoxide. The catalyst has a high selectivity and is based on easily available metal compounds....

  13. Selective Hydrogenation of Acetylene over Pd, Au, and PdAu Supported Nanoparticles

    Science.gov (United States)

    Walker, Michael P.

    The removal of trace amounts of acetylene in ethylene streams is a high-volume industrial process that must possess high selectivity of alkyne hydrogenation over hydrogenation of alkenes. Current technology uses metallic nanoparticles, typically palladium or platinum, for acetylene removal. However, problems arise due to the deactivation of the catalysts at high temperatures as well as low selectivities at high conversions. Pore expanded MCM-41 is synthesized via a two-step strategy in which MCM-41 was prepared via cetyltrimethylammonium bromide (CTMABr) followed by the hydrothermal treatment with N,N-dimethyldecylamine (DMDA). This material was washed with ethanol to remove DMDA, or calcined to remove both surfactants. PE-MCM-41 based materials were impregnated with palladium, gold, and palladium-gold nanoparticles. The removal of DMDA had an effect on both the conversion and selectivity, in which they were found to drop significantly. However, by using the bimetallic PdAu catalysts, higher selectivity could be achieved due to increased electron density.

  14. Experimental and theoretical studies of the reaction between cationic vanadium oxide clusters and acetylene

    Institute of Scientific and Technical Information of China (English)

    YIN Shi; MA YanPing; DU Lin; HE ShengGui; GE MaoFa

    2008-01-01

    The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters (VmO+n) toward acetylene (C2H2) molecules under gas phase (P, ~ 1.14 kPa), under near room temperature (T, ~ 350 K) conditions. Association products, VmOnC2H+2 (m,n = 2,4; 2,6; 3,7-8; 4,9-11; 5,12-13;6,13-16, and 7,17), are observed. The oxidation of C2H2 by (V2O5)+n, (n = 1-3) is experimentally identified.The reactivity of (V2O5)+n decreases as n increases. Density functional theory (DFT) calculations were carried out to interpret the reaction mechanisms. The DFT results indicate that a terminal oxygen atom from V2O+5 can transfer overall barrierlessly to C2H2 at room temperature, which is in agreement with the experimental observation. Other experimental results such as the observation of V2O6C2H+2 and nonobservation of V2O7,8C2H+2 in the experiments are also well interpreted based on the DFT calculations.The reactivity of vanadium oxide clusters toward acetylene and other hydrocarbons may be considered in identifying molecular level mechanisms for related heterogeneous catalysis.

  15. π Type Lithium Bond Interaction between Ethylene,Acetylene,or Benzene and Amido-lithium

    Institute of Scientific and Technical Information of China (English)

    YUAN,Kun; LIU,Yanzhi; L(U),Lingling; ZHU,Yuancheng; ZHANG,Ji; ZHANG,dunyan

    2009-01-01

    The optimization geometries and interaction energy corrected by basis set super-position error (BSSE) of the lithium bond complexes between ethylene,acetylene,or benzene and amido-lithium have been calculated at the B3L YP/6-311++G** and MP2/6-311 ++-G** levels.And only one configuration was obtained for each lithium bond system.All the equilibrium geometries were confirmed to be stable state by analytical frequency computations.The calculations showed that all the N(2)-Li(4) bond lengths increased obviously and the red shift of N(2)-Li(4) stretching frequency occurred after complexes formed.The calculated binding energies with BSSE and zero-point vibrational energy corrections of complexes Ⅰ,Ⅱ and Ⅲ are -26.04,-24.86 and -30.02 kJ·mol-1 via an MP2 method,respectively.Natural bond orbital (NBO) theory analysis revealed that the three complexes were all formed with π type lithium bond interaction between ethylene,acetylene,or benzene and amido-lithium.

  16. Designing zeolite catalysts for size- and shape-selective reactions: Selective hydrogenation of acetylene in the presence of butadiene and ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Corbin, D.R.; Abrams, L.; Bonifaz, C. (E.I. du Pont de Nemours Company, Wilmington, DE (USA))

    1989-02-01

    In the production of ethylene from the steam cracking of natural gas, small amounts of acetylene and butadiene are produced. Downstream, acetylene can present a hazard in a cryogenic separation process while nonselective hydrogenation removes acetylene as well as valuable ethylene and butadiene. With the aid of adsorption measurements, a selective hydrogenation catalyst has been designed. Small-pore zeolites, which serve as catalytic supports and provide reactant selective control, were ion-exchanged with Ni{sup 2+} and subsequently reduced. Compared to a commercial catalyst in which 60% of butadiene and all of the acetylene are hydrogenated, these new catalysts totally hydrogenate acetylene with only 10-20% hydrogenation of the butadiene and almost no hydrogenation of ethylene. To achieve selective hydrogenation, poisoning of the metal sites on the external zeolite surface is essential in order to obtain a product spectrum dominated by catalytic sites within the zeolite framework.

  17. COMPUTER SYSTEM AND MODELLING OF THREATS TO ENERGY SECURITY OF MOLDOVA IN CASE OF INTERSYSTEM COMMUNICATION DISCONNECTION

    Directory of Open Access Journals (Sweden)

    Bicova E.V.

    2010-12-01

    Full Text Available In the paper modeling of a group of scenarios of threats to energetic security of Moldovan energy system, which occur in case of disconnecting (or limitation of cross-flows of electricity of 330 kV transmission line Balti-Dniester HPS. It was used for analysis a software application for energy security monitoring. The application has been developed in IE ASM.

  18. PPP-RTK and inter-system biases: the ISB look-up table as a means to support multi-system PPP-RTK

    Science.gov (United States)

    Khodabandeh, A.; Teunissen, P. J. G.

    2016-09-01

    PPP-RTK has the potential of benefiting enormously from the integration of multiple GNSS/RNSS systems. However, since unaccounted inter-system biases (ISBs) have a direct impact on the integer ambiguity resolution performance, the PPP-RTK network and user models need to be flexible enough to accommodate the occurrence of system-specific receiver biases. In this contribution we present such undifferenced, multi-system PPP-RTK full-rank models for both network and users. By an application of {S}-system theory, the multi-system estimable parameters are presented, thereby identifying how each of the three PPP-RTK components are affected by the presence of the system-specific biases. As a result different scenarios are described of how these biases can be taken into account. To have users benefit the most, we propose the construction of an ISB look-up table. It allows users to search the table for a network receiver of their own type and select the corresponding ISBs, thus effectively realizing their own ISB-corrected user model. By applying such corrections, the user model is strengthened and the number of integer-estimable user ambiguities is maximized.

  19. Vibration-rotation pattern in acetylene. II. Introduction of Coriolis coupling in the global model and analysis of emission spectra of hot acetylene around 3 microm.

    Science.gov (United States)

    Amyay, Badr; Robert, Séverine; Herman, Michel; Fayt, André; Raghavendra, Balakrishna; Moudens, Audrey; Thiévin, Jonathan; Rowe, Bertrand; Georges, Robert

    2009-09-21

    A high temperature source has been developed and coupled to a high resolution Fourier transform spectrometer to record emission spectra of acetylene around 3 mum up to 1455 K under Doppler limited resolution (0.015 cm(-1)). The nu(3)-ground state (GS) and nu(2)+nu(4)+nu(5) (Sigma(u) (+) and Delta(u))-GS bands and 76 related hot bands, counting e and f parities separately, are assigned using semiautomatic methods based on a global model to reproduce all related vibration-rotation states. Significantly higher J-values than previously reported are observed for 40 known substates while 37 new e or f vibrational substates, up to about 6000 cm(-1), are identified and characterized by vibration-rotation parameters. The 3 811 new or improved data resulting from the analysis are merged into the database presented by Robert et al. [Mol. Phys. 106, 2581 (2008)], now including 15 562 lines accessing vibrational states up to 8600 cm(-1). A global model, updated as compared to the one in the previous paper, allows all lines in the database to be simultaneously fitted, successfully. The updates are discussed taking into account, in particular, the systematic inclusion of Coriolis interaction.

  20. Rhodium(III)-Catalyzed C-H Activation/Annulation with Vinyl Esters as an Acetylene Equivalent

    OpenAIRE

    Webb, NJ; Marsden, SP; Raw, SA

    2014-01-01

    The behavior of electron-rich alkenes in rhodium-catalyzed C–H activation/annulation reactions is investigated. Vinyl acetate emerges as a convenient acetylene equivalent, facilitating the synthesis of sixteen 3,4-unsubstituted isoquinolones, as well as select heteroaryl-fused pyridones. The complementary regiochemical preferences of enol ethers versus enol esters/enamides is discussed

  1. Carbon material formation on SBA-15 and Ni-SBA-15 and residue constituents during acetylene decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Hung-Lung, E-mail: hlchiang@mail.cmu.edu.tw [Department of Risk Management, China Medical University, Taichung 40402, Taiwan (China); Wu, Trong-Neng [Department of Public Health, China Medical University, Taichung 40402, Taiwan (China); Ho, Yung-Shou [Department of Applied Chemistry and Materials Science, Fooyin University, Kaohsiung 831, Taiwan (China); Zeng, Li-Xuan [Department of Risk Management, China Medical University, Taichung 40402, Taiwan (China)

    2014-07-15

    Highlights: • Acetylene was decomposed on SBA-15 and Ni-SBA-15 at 650–850 °C. • Carbon spheres and filaments were formed after acetylene decomposition. • PAHs were determined in tar and residues. • Exhaust constituents include CO{sub 2}, H{sub 2}, NO{sub x} and hydrocarbon species. - Abstract: Carbon materials including carbon spheres and nanotubes were formed from acetylene decomposition on hydrogen-reduced SBA-15 and Ni-SBA-15 at 650–850 °C. The physicochemical characteristics of SBA-15, Ni-SBA-15 and carbon materials were analyzed by field emission scanning electronic microscopy (FE-SEM), Raman spectrometry, and energy dispersive spectrometry (EDS). In addition, the contents of polyaromatic hydrocarbons (PAHs) in the tar and residue and volatile organic compounds (VOCs) in the exhaust were determined during acetylene decomposition on SBA-15 and Ni-SBA-15. Spherical carbon materials were observed on SBA-15 during acetylene decomposition at 750 and 850 °C. Carbon filaments and ball spheres were formed on Ni-SBA-15 at 650–850 °C. Raman spectroscopy revealed peaks at 1290 (D-band, disorder mode, amorphous carbon) and 1590 (G-band, graphite sp{sup 2} structure) cm{sup −1}. Naphthalene (2 rings), pyrene (4 rings), phenanthrene (3 rings), and fluoranthene (4 rings) were major PAHs in tar and residues. Exhaust constituents of hydrocarbon (as propane), H{sub 2}, and C{sub 2}H{sub 2} were 3.9–2.6/2.7–1.5, 1.4–2.8/2.6–4.3, 4.2–2.4/3.2–1.7% when acetylene was decomposed on SBA-15/Ni-SBA-15, respectively, corresponding to temperatures ranging from 650 to 850 °C. The concentrations of 52 VOCs ranged from 9359 to 5658 and 2488 to 1104 ppm for SBA-15 and Ni-SBA-15 respectively, at acetylene decomposition temperatures from 650 to 850 °C, and the aromatics contributed more than 87% fraction of VOC concentrations.

  2. Analysis for Mar Vel Black and acetylene soot low reflectivity surfaces for star tracker sunshade applications

    Science.gov (United States)

    Yung, E.

    1974-01-01

    Mar Vel Black is a revolutionary new extremely low reflectivity anodized coating developed by Martin Marietta of Denver. It is of great interest in optics in general, and in star trackers specifically because it can reduce extraneous light reflections. A sample of Mar Vel Black was evaluated. Mar Vel Black looks much like a super black surface with many small peaks and very steep sides so that any light incident upon the surface will tend to reflect many times before exiting that surface. Even a high reflectivity surface would thus appear to have a very low reflectivity under such conditions. Conversely, acetylene soot does not have the magnified surface appearance of a super black surface. Its performance is, however, predictable from the surface structure, considering the known configuration of virtually pure carbon.

  3. Analysis of Effluent Gases During the CCVD Growth of Multi Wall Carbon Nanotubes from Acetylene

    Science.gov (United States)

    Schmitt, T. C.; Biris, A. S.; Miller, D. W.; Biris, A. R.; Lupu, D.; Trigwell, S.; Rahman, Z. U.

    2005-01-01

    Catalytic chemical vapor deposition was used to grow multi-walled carbon nanotubes on a Fe:Co:CaCO3 catalyst from acetylene. The influent and effluent gases were analyzed by gas chromatography and mass spectrometry at different time intervals during the nanotubes growth process in order to better understand and optimize the overall reaction. A large number of byproducts were identified and it was found that the number and the level for some of the carbon byproducts significantly increased over time. The CaCO3 catalytic support thermally decomposed into CaO and CO2 resulting in a mixture of two catalysts for growing the nanotubes, which were found to have outer diameters belonging to two main groups 8 to 35 nm and 40 to 60 nm, respectively.

  4. Shock-tube pyrolysis of acetylene - Sensitivity analysis of the reaction mechanism for soot formation

    Science.gov (United States)

    Frenklach, M.; Clary, D. W.; Gardiner, W. C., Jr.; Stein, S. E.

    1986-01-01

    The impact of thermodynamic parameters on the sensitivity of model predictions of soot formation by shock-tube pyrolysis of acetylene were assessed analytically. The pyrolysis process was treated as having three components: initiation, the initial pyrolysis stages; cyclization, formation of larger molecules and radicals and small aromatic molecules; and polymerization, further growth of aromatic rings. Rate equations are reviewed for each component. Thermodynamic effects were assessed by varying the C2H-H and C2H3-H bond energies and the Ct-(Ct) group additivity value. Any change in the C2H-H bond energy had a significant impact on the temperature and the maximum amount of the soot yield. The findings underscore the necessity of using accurate thermodynamic data for modeling high-temperature chemical kinetics.

  5. Synthesis, structure and cytotoxic activity of acetylenic derivatives of betulonic and betulinic acids

    Science.gov (United States)

    Bębenek, Ewa; Chrobak, Elwira; Wietrzyk, Joanna; Kadela, Monika; Chrobak, Artur; Kusz, Joachim; Książek, Maria; Jastrzębska, Maria; Boryczka, Stanisław

    2016-02-01

    A series of acetylenic derivatives of betulonic and betulinic acids has been synthesized and characterized by 1H and 13C NMR, IR and MS spectroscopy. The structure of propargyl betulonate 4 and propargyl betulinate-DMF solvate 8A was solved by X-ray diffraction. Thermal properties were examined using a DSC technique. The resulting alkynyl derivatives, as well as betulin 1 and betulinic acid 3, were evaluated in vitro for their cytotoxic activity against human T47D breast cancer, CCRF/CEM leukemia, SW707 colorectal, murine P388 leukemia and BALB3T3 normal fibroblasts cell lines. Several of the obtained compounds have a favorable cytotoxic profile than betulin 1. Propargyl betulinate 8 was the most active derivative, being up to 3-fold more potent than betulin 1 against the human leukemia (CCRF/CEM) cell line, with an IC50 value of 3.9 μg/mL.

  6. A New Acetylenic Compound and Other Bioactive Metabolites from a Shark Gill-derived Penicillium Strain

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2016-09-01

    Full Text Available Nine chiral compounds (1−9 were isolated from the static fermentation culture of a shark gill-derived fungus Penicillium polonicum AP2T1. These compounds include a new acetylenic aromatic ether (1 , (--WA , four alkaloids ( a urantiomide C ( 2 , fructigenine A (3, cyclopenin (4 and cyclopenol (5 and four oxygenated compounds ((R-penipratynolene (6, (3S,4S-3,4-dihydro-3,4,8-trihydroxyl-naphthalenone (7, verrucosidin (8 and norverrucosidin (9. Their structures were elucidated by MS, NMR , optical rotation and circular dichroism (CD . In antimicrobial tests , compounds 1–4, 6 and 8–9 showed weak antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and/or Escherichia coli.Compounds 3, 8 and 9 also exhibited moderate toxicity against Artemia salina larva , and showed cytotoxicity against human colon cancer cell line HCT116.

  7. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    CERN Document Server

    Karhu, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L

    2016-01-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, $\

  8. A novel metal-organic framework for high storage and separation of acetylene at room temperature

    Science.gov (United States)

    Duan, Xing; Wang, Huizhen; Ji, Zhenguo; Cui, Yuanjing; Yang, Yu; Qian, Guodong

    2016-09-01

    A novel 3D microporous metal-organic framework with NbO topology, [Cu2(L)(H2O)2]•(DMF)6·(H2O)2 (ZJU-10, ZJU = Zhejiang University; H4L =2‧-hydroxy-[1,1‧:4‧,1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid; DMF =N,N-dimethylformamide), has been synthesized and structurally characterized. With suitable pore sizes and open Cu2+ sites, ZJU-10a exhibits high BET surface area of 2392 m2/g, as well as moderately high C2H2 volumetric uptake capacity of 132 cm3/cm3. Meanwhile, ZJU-10a is a promising porous material for separation of acetylene from methane and carbon dioxide gas mixtures at room temperature.

  9. Dubinin-Astakhov model for acetylene adsorption on metal-organic frameworks

    Science.gov (United States)

    Cheng, Peifu; Hu, Yun Hang

    2016-07-01

    Acetylene (C2H2) is explosive at a pressure above 29 psi, causing a safety issue for its storage and applications. C2H2 adsorption on metal-organic frameworks (MOFs) has been explored to solve the issue. However, a suitable isotherm equation for C2H2 adsorption on various MOFs has not been found. In this paper, it was demonstrated that Dubinin-Astakhov equation can be exploited as a general isotherm model to depict C2H2 adsorption on MOF-5, ZIF-8, HKUST-1, and MIL-53. In contrast, commonly used Langmuir and BET models exhibited their inapplicability for C2H2 adsorption on those MOFs.

  10. Computational simulations of hydrogen circular migration in protonated acetylene induced by circularly polarized light.

    Science.gov (United States)

    Shi, Xuetao; Li, Wen; Schlegel, H Bernhard

    2016-08-28

    The hydrogens in protonated acetylene are very mobile and can easily migrate around the C2 core by moving between classical and non-classical structures of the cation. The lowest energy structure is the T-shaped, non-classical cation with a hydrogen bridging the two carbons. Conversion to the classical H2CCH(+) ion requires only 4 kcal/mol. The effect of circularly polarized light on the migration of hydrogens in oriented C2H3 (+) has been simulated by Born-Oppenheimer molecular dynamics. Classical trajectory calculations were carried out with the M062X/6-311+G(3df,2pd) level of theory using linearly and circularly polarized 32 cycle 7 μm cosine squared pulses with peak intensity of 5.6 × 10(13) W/cm(2) and 3.15 × 10(13) W/cm(2), respectively. These linearly and circularly polarized pulses transfer similar amounts of energy and total angular momentum to C2H3 (+). The average angular momentum vectors of the three hydrogens show opposite directions of rotation for right and left circularly polarized light, but no directional preference for linearly polarized light. This difference results in an appreciable amount of angular displacement of the three hydrogens relative to the C2 core for circularly polarized light, but only an insignificant amount for linearly polarized light. Over the course of the simulation with circularly polarized light, this corresponds to a propeller-like motion of the three hydrogens around the C2 core of protonated acetylene. PMID:27586924

  11. Computational simulations of hydrogen circular migration in protonated acetylene induced by circularly polarized light

    Science.gov (United States)

    Shi, Xuetao; Li, Wen; Schlegel, H. Bernhard

    2016-08-01

    The hydrogens in protonated acetylene are very mobile and can easily migrate around the C2 core by moving between classical and non-classical structures of the cation. The lowest energy structure is the T-shaped, non-classical cation with a hydrogen bridging the two carbons. Conversion to the classical H2CCH+ ion requires only 4 kcal/mol. The effect of circularly polarized light on the migration of hydrogens in oriented C2H3+ has been simulated by Born-Oppenheimer molecular dynamics. Classical trajectory calculations were carried out with the M062X/6-311+G(3df,2pd) level of theory using linearly and circularly polarized 32 cycle 7 μm cosine squared pulses with peak intensity of 5.6 × 1013 W/cm2 and 3.15 × 1013 W/cm2, respectively. These linearly and circularly polarized pulses transfer similar amounts of energy and total angular momentum to C2H3+. The average angular momentum vectors of the three hydrogens show opposite directions of rotation for right and left circularly polarized light, but no directional preference for linearly polarized light. This difference results in an appreciable amount of angular displacement of the three hydrogens relative to the C2 core for circularly polarized light, but only an insignificant amount for linearly polarized light. Over the course of the simulation with circularly polarized light, this corresponds to a propeller-like motion of the three hydrogens around the C2 core of protonated acetylene.

  12. Acetylene C2H 2 retrievals from MIPAS data and regions of enhanced upper tropospheric concentrations in August 2003

    Directory of Open Access Journals (Sweden)

    V. P. Kanawade

    2011-10-01

    Full Text Available Acetylene (C2H2 volume mixing ratios (VMRs have been successfully retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS Level 1B radiances during August 2003, providing the first global map of such data and ratios to CO in the literature. The data presented here contain most information between 300 hPa and 100 hPa with systematic errors less than 10% at the upper levels. Random errors per point are less than 15% at lower levels and are closer to 30% at 100 hPa. Global distributions of the C2H2 and C2H2/CO ratio confirm significant features associated with both the Asian monsoon anticyclone and biomass burning for this important hydrocarbon in a characteristic summer month (August 2003, showing tight correlations regionally, particularly at lower to medium values, but globally emphasising the differences between sources and lifetimes of CO and C2H2. The correlations are seen to be particularly disturbed in the regions of highest C2H2 concentrations, indicating variability in the surface emissions or fast processing. A strong isolation of C2H2 within the Asian monsoon anticyclone is observed, evidencing convective transport into the upper troposphere, horizontal advection within the anticyclone at 200 hPa, distinct gradients at the westward edge of the vortex and formation of a secondary dynamical feature from the eastward extension of the anticyclone outflow over the Asian Pacific. Ratios of C2H2/CO are consistent with the evidence from the cross-sections that the C2H2 is uplifted rapidly in convection. Observations are presented of enhanced C2H2 associated with the injection from biomass burning into the upper troposphere and the outflow from Africa at 200 hPa into both the Atlantic and Indian Oceans. In the biomass burning regions, C2H2 and CO are well correlated, but the uplift is less marked and peaks at lower altitudes compared to the strong effects observed in the Asian monsoon anticyclone. Ratios of C2H2/CO

  13. SYNTHESIS OF THE COPOLYMERS OF p-DIETHYNYLBENZENE WITH OTHER ACETYLENIC DERIVATIVES INITIATED BY (Ph3P)2 PdCl2

    Institute of Scientific and Technical Information of China (English)

    LI Yinkui; Chen Zhaohui

    1993-01-01

    The copolymerization of p- diethynylbenzene (PDEB) with phenylacetylene ( PhA ), 4, 4 '-diethynylbiphenyl ( DEBP )or m-diethynylbenzene (MDEB) are studied by varying mole ratios of monomers. When the mole ratios of PDEB/PhA are less or equal to 1/5, the copolymers are soluble and fusible, but the other copolymers are insoluble and infusible. The results show that the good solvent of cross-linked copolymers is benzene and their solubility parameter is 9.15 cal0.5.cm- 1.5. And their swellability (θp), Huggins parameter (χ), density (d245) and the average molecular weights between crosslinks (-Mc) are measured. It is found that θp and -Mc of copolymers are greater but d25 4is less than that of respective homopolymers. IR spectra show that the copolymers have transoid configuration and small number of unreacted ethynyl groups exist in the copolymers. The mechanism about the polymerization or acetylenic derivatives initiated by (Ph3P)2PdCl2 is dis cussed.

  14. A model for the ethylene and acetylene adsorption on the surface of Cun(n = 10-15) nanoclusters: A theoretical study

    Science.gov (United States)

    Farmanzadeh, Davood; Abdollahi, Tahereh

    2016-11-01

    In this work, we report the results of density functional theory calculations of ethylene and acetylene adsorption on the most stable Cun (n = 10-15) nanoclusters, in two π and di- σ adsorption modes. Both the hydrocarbons molecularly adsorbed on the surface. Our results show that the quality of interaction of ethylene and acetylene with odd copper nanoclusters (n = 11, 13, 15) is different from what is found on even copper nanoclusters (n = 10, 12, 14). One of the interesting features of this adsorption is that acetylene never orient toward di-σ mode for Cusbnd Cu bond in odd copper nanoclusters. Also, for di- σ-CunC2H4, no stable structure is identified. The highest interaction and deformation energies are seen for the adsorption of acetylene and ethylene on Cu11 in π-mode.

  15. Slow intramolecular vibrational redistribution: the latest results for trifluoropropyne, a comparison with the other terminal acetylenes and the mechanism*

    Science.gov (United States)

    Malinovsky, A. L.; Makarov, A. A.; Ryabov, E. A.

    2012-05-01

    We studied the dynamics of intramolecular vibrational redistribution (IVR) from the initially excited mode ν1≈3330 cm-1 (acetylene-type H-C bond) in H{-}C\\equivC{-}CF_3 molecules in the gaseous phase by means of time-resolved anti-Stokes spontaneous Raman scattering. The time constant of this process was estimated as 2.3 ns—this is the slowest IVR time reported so far for the room-temperature gases. We have compared this result with earlier results on the other terminal acetylene molecules, and give an explanation of this low IVR rate. Our suggestion for it follows from an assumption that the most probable doorway state leading to IVR from \

  16. 甲烷部分氧化制乙炔过程研究%A Study of Acetylene Production by Methane Flaming in a Partial Oxidation Reactor

    Institute of Scientific and Technical Information of China (English)

    刘业飞; 王铁峰; 李庆勋; 王德峥

    2011-01-01

    The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry. The partial oxidation reactor is the key to high acetylene yields. This work is an experimental and numerical study on the use of a methane flame to produce acetylene. A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames. The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures, and these were compared to numerical results from Computational Fluid Dynamics (CFD) simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function (RANS-PDF) approach coupled with detailed chemical mechanisms. The Leeds 1.5, GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms. The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied. The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane. Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6. Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time. So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.

  17. Quantum Chemical Evaluation of the Astrochemical Significance of Reactions between S Atom and Acetylene or Ethylene

    Science.gov (United States)

    Woon, David E.

    2007-01-01

    Addition-elimination reactions of S atom in its P-3 ground state with acetylene (C2H2) and ethylene (C2H4) were characterized with both molecular orbital and density functional theory calculations employing correlation consistent basis sets in order to assess the likelihood either reaction might play a general role in astrochemistry or a specific role in the formation of S2 (X (sup 3 SIGMA (sub g) (sup -)) via a mechanism proposed by Saxena and Misra (Mon. Not. R. Astron. Soc. 1995, 272, 89). The acetylene and ethylene reactions proceed through C2H2S ((sup 3)A")) and C2H4S ((sup 3)A")) intermediates, respectively, to yield HCCS ((sup 2)II)) and C2H3S ((sup 2)A')). Substantial barriers were found in the exit channels for every combination of method and basis set considered in this work, which effectively precludes hydrogen elimination pathways for both S + C2H2 and S + C2H4 in the ultracold interstellar medium where only very modest barriers can be surmounted and processes without barriers tend to predominate. However, if one or both intermediates is formed and stabilized efficiently under cometary or dense interstellar cloud conditions, they could serve as temporary reservoirs for S atom and participate in reactions such as S + C2H2S (right arrow) S2 = C2H2 or S + C2H4S (right arrow) S2 + C2H4. For formation and stabilization to be efficient, the reaction must possess a barrier height small enough to be surmountable at low temperatures yet large enough to prevent redissociation to reactants. Barrier heights computed with B3LYP and large basis sets are very low, but more rigorous QCISD(T) and RCCSD(T) results indicate that the barrier heights are closer to 3-4 kcal/mol. The calculations therefore indicate that S + C2H2 or S + C2H4 could contribute to the formation of S2 in comets and may serve as a means to gauge coma temperature. The energetics of the ethylene reaction are more favorable.

  18. Frequency Comb-Referenced Spectroscopy in the ν1 + ν3 Region of Acetylene

    Science.gov (United States)

    Cich, Matthew J.; Forthomme, Damien; Hall, Gregory E.; Mcraven, Christopher P.; Sears, Trevor J.; Twagirayezu, Sylvestre

    2014-06-01

    class="MsoNormal">By using saturation dip absorption spectroscopy with an extended cavity diode laser locked to a frequency comb, we have measured the rest frequencies of transitions in the ν4 = 1 and ν5 = 1 hot bands in the ν1 + ν3 combination band of acetylene. The measured line frequencies are accurate to approximately 20 kHz i.e. approximately one part in 1011. Positions of the hot-band lines quoted in the HITRAN database, which are derived from the analysis of high-resolution FTIR spectra, are of the order of 10's of MHz in error. These measurements were undertaken because pressure broadened lineshape measurements of rotational lines in the combination band indicated that weak underlying hot band features were not correctly accounted for on the basis of their previously reported positions. As a result, measured line profiles in the band could not be accurately fit leading to errors of up to 1% in acetylene concentrations derived from the measurements. In addition, the pressure broadened P(11) line in the ν1 + ν3 combination band has been studied as a function of varying concentration of the absorber in nitrogen. Mixture concentrations of 1, 5 and 10% at 296 K and pressures between a few Torr and one atmosphere were made and the measurements analyzed using two different speeddependent broadening models. These experiments are designed to test the additivity of contributions to pressure broadening and shift in speed-dependent line-shape modeling, i.e. whether the lineshape parameters follow partial pressure weighting in the binary mixtures. P(11) is relatively isolated with respect to underlying hot band transitions and neighboring transitions of the same band, but it was found that the accurate positions of underlying hot-band transitions were crucial to the successful modeling of the observed line shapes, even though these lines are typically 100-1000 times weaker than P(11) itself and are many Doppler line widths removed from the line center

  19. Growth of bridging carbon nanofibers in cracks formed by heat-treating iron oxide thin sheets in acetylene gas

    OpenAIRE

    Takeshi Hikata; Soichiro Okubo; Yugo Higashi; Teruaki Matsuba; Risa Utsunomiya; Sadahiro Tsurekawa; Katsuhisa Murakami; Jun-ichi Fujita

    2013-01-01

    We produced novel carbon nanofibers (CNFs) by oxidizing high-purity iron foil and then carburizing it in acetylene gas flow. This formed cracks in the heat-treated iron foil with CNFs bridging the two walls of each crack. The CNFs were drawn out from the walls as the crack opened during heat treatment. This will be a new method to grow and arrange carbon nanotubes and nanosheets without using metal nanoparticles or template substrates.

  20. Growth of bridging carbon nanofibers in cracks formed by heat-treating iron oxide thin sheets in acetylene gas

    Directory of Open Access Journals (Sweden)

    Takeshi Hikata

    2013-04-01

    Full Text Available We produced novel carbon nanofibers (CNFs by oxidizing high-purity iron foil and then carburizing it in acetylene gas flow. This formed cracks in the heat-treated iron foil with CNFs bridging the two walls of each crack. The CNFs were drawn out from the walls as the crack opened during heat treatment. This will be a new method to grow and arrange carbon nanotubes and nanosheets without using metal nanoparticles or template substrates.

  1. Importance of surface carbide formation on the activity and selectivity of Pd surfaces in the selective hydrogenation of acetylene

    Science.gov (United States)

    Yang, Bo; Burch, Robbie; Hardacre, Christopher; Hu, P.; Hughes, Philip

    2016-04-01

    A recent experimental investigation (Kim et al. J. Catal. 306 (2013) 146-154) on the selective hydrogenation of acetylene over Pd nanoparticles with different shapes concluded that Pd(100) showed higher activity and selectivity than Pd(111) for acetylene hydrogenation. However, our recent density functional calculations (Yang et al. J. Catal. 305 (2013) 264-276) observed that the clean Pd(111) surface should result in higher activity and ethylene selectivity compared with the clean Pd(100) surface for acetylene hydrogenation. In the current work, using density functional theory calculations, we find that Pd(100) in the carbide form gives rise to higher activity and selectivity than Pd(111) carbide. These results indicate that the catalyst surface is most likely in the carbide form under the experimental reaction conditions. Furthermore, the adsorption energies of hydrogen atoms as a function of the hydrogen coverage at the surface and subsurface sites over Pd(100) are compared with those over Pd(111), and it is found that the adsorption of hydrogen atoms is always less favoured on Pd(100) over the whole coverage range. This suggests that the Pd(100) hydride surface will be less stable than the Pd(111) hydride surface, which is also in accordance with the experimental results reported.

  2. Molecular Heterogeneous Catalysis: a Single-Site Zeolite-Supported Rhodium Complex for Acetylene Cyclotrimerization

    International Nuclear Information System (INIS)

    By anchoring metal complexes to supports, researchers have attempted to combine the high activity and selectivity of molecular homogeneous catalysis with the ease of separation and lack of corrosion of heterogeneous catalysis. However, the intrinsic nonuniformity of supports has limited attempts to make supported catalysts truly uniform. We report the synthesis and performance of such a catalyst, made from (Rh(C2H4)2(CH3COCHCOCH3)) and a crystalline support, dealuminated Y zeolite, giving {Rh(C2H4)2} groups anchored by bonds to two zeolite oxygen ions, with the structure determined by extended X-ray absorption fine structure (EXAFS) spectroscopy and the uniformity of the supported complex demonstrated by 13C NMR spectroscopy. When the ethylene ligands are replaced by acetylene, catalytic cyclotrimerization to benzene ensues. Characterizing the working catalyst, we observed evidence of intermediates in the catalytic cycle by NMR spectroscopy. Calculations at the level of density functional theory confirmed the structure of the as-synthesized supported metal complex determined by EXAFS spectroscopy. With this structure as an anchor, we used the computational results to elucidate the catalytic cycle (including transition states), finding results in agreement with the NMR spectra.

  3. Nitrogen fixation (acetylene reduction) by annual winter legumes on a coal surface mine

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielson, F.C.

    1982-01-01

    The winter annuals, crimson clover, rose clover, subterranean clover and hairy vetch, were evaluated for their ability to fix nitrogen on coal surface mine substrates by measuring their ability to reduce acetylene to ethylene. The effects of fertilizer, Abruzzi ryegrass, Kentucky 31 fescue grass and a phytotoxic plant Chenopodium album on nitrogen fixation was also assessed. Crimson clover was recommended as the best legume to use on topsoil and shale in the South. Hairy vetch gave good results on shale and subterranean clover did well on topsoil. The use of these species for revegetation is discussed. Overall, no correlation between substrate pH and ethylene levels was found and effects of substrate depended upon the legume species. Super phosphate fertilizer supported less nitrogen fixation than 13-13-13. Abruzzi ryegrass in some unknown way inhibited plant density and nitrogen fixation by legumes but not by free living substrate micro-organisms. Shale from under dead Chenopodium plants in both field and greenhouse experiments did not inhibit nitrogen fixation. 11 references, 7 tables.

  4. Nitrogen fixation (Acetylene Reduction) by annual winter legumes on a coal surface mine

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielson, F.C.

    1982-01-01

    The winter annuals, crimson clover, rose clover, subterranean clover and hairy vetch, were evaluated for nitrogen fixing capacity on coal surface mine substrates by measuring their ability to reduce acetylene to ethylene. The effects of fertilizer, Abruzzi rye, Kentucky 31 fescue grass and a phytotoxic plant Chenopodium album on nitrogen fixation were also assessed. Crimson clover was recommended as the best legume to use on topsoil and shale in the south. Hairy vetch gave good results on shale and subterranean clover did well on topsoil. The use of these species for revegetation is discussed. Overall, no correlation between substrate pH and ethylene levels was found and effects of substrate depended upon the legume species. Super phosphate fertilizer supported less nitrogen fixation than 13-13-13. Abruzzi rye in some unknown way inhibited plant density and nitrogen fixation by legumes but not by free living substrate micro-organisms. Shale from under dead Chenopodium plants in both field and greehouse experiments did not inhibit nitrogen fixation. 7 tables.

  5. Theoretical investigation of alignment-dependent intense-field fragmentation of acetylene

    Science.gov (United States)

    Doblhoff-Dier, Katharina; Kitzler, Markus; Gräfe, Stefanie

    2016-07-01

    We analyze the alignment-dependent dissociative and nondissociative ionization of acetylene, C2H2 . Numerical models describing the yield of the singly and doubly charged ions (C2H2+,C2H22 +) and several fragmentation and isomerization channels (C2H++H+ ,CH++CH+ ,CH2++C+ ) as a function of the relative alignment angle between the laser polarization axis and the molecular axis are presented. We apply and compare two different approaches. The first is based on time-dependent density functional theory. The second is a quasi-single-particle approach using the Dyson orbitals. We find good agreement between the results of both methods. A comparison of our theoretical predictions with experimental data allows us to show that the alignment-dependent yield of most reaction channels is described to high accuracy assuming sequential ionization. However, for some of the fragmentation channels, namely, CH++CH+ and C2H++H+ , we find non-negligible influence of recollisional ionization.

  6. Inlet effect on the coal pyrolysis to acetylene in a hydrogen plasma downer reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Y.; Chen, J.Q.; Ding, Y.L.; Jin, Y. [Tsinghua Univ., Beijing (China). Dept. of Chemical Engineering, Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology; Xiong, X.Y. [Xinjiang Tianye Corp., Shihezi (China)

    2008-06-15

    In this study a gas-solid downer reactor was used to characterize high temperature reactions of coal pyrolysis. The aim of the study was to examine the influence of the coal injection design on reactor performance in a 2 MW plasma reactor. Computational fluid dynamics (CFD) simulations were used to model complex reacting flows in the coal pyrolysis process in order to examine the effects of nozzle design on the initial distribution of the coal particles. A 2-fluid model was used to calculate solids viscosity and pressure from the kinetic theory of granular flow as well as to solve partial differential equations for granular temperatures. Results of the simulations showed that gas flow and particle jets through the nozzles played a significant role in the distribution of the coal particles. Coal dispersion at the inlet was dependent on flow conditions. Flat-shaped nozzles provided flexible control on gas-particle contacts during the initial stages. When the layout of the nozzles was tuned, solids flow formed either swirling or non-swirling actions in the reactor. It was concluded that the volume fraction of the acetylene in the product gas was increased by more than 20 per cent when the nozzles were optimally arranged. 9 refs., 1 tab., 8 figs.

  7. Diffusion air effects on the soot axial distribution concentration in a premixed acetylene/air flame

    Energy Technology Data Exchange (ETDEWEB)

    Fassani, Fabio Luis; Santos, Alex Alisson Bandeira; Goldstein Junior, Leonardo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia Termica e de Fluidos]. E-mails: fassani@fem.unicamp.br; absantos@fem.unicamp.br; leonardo@fem.unicamp.br; Ferrari, Carlos Alberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica. Dept. de Eletronica Quantica]. E-mail: ferrari@ifi.unicamp.br

    2000-07-01

    Soot particles are produced during the high temperature pyrolysis or combustion of hydrocarbons. The emission of soot from a combustor, or from a flame, is determined by the competition between soot formation and its oxidation. Several factors affect these processes, including the type of fuel, the air-to-fuel ratio, flame temperature, pressure, and flow pattern. In this paper, the influence of the induced air diffusion on the soot axial distribution concentration in a premixed acetylene/air flame was studied. The flame was generated in a vertical axis burner in which the fuel - oxidant mixture flow was surrounded by a nitrogen discharge coming from the annular region between the burner tube and an external concentric tube. The nitrogen flow provided a shield that protected the flame from the diffusion of external air, enabling its control. The burner was mounted on a step-motor driven, vertical translation table. The use of several air-to-fuel ratios made possible to establish the sooting characteristics of this flame, by measuring soot concentration along the flame height with a non-intrusive laser light absorption technique. (author)

  8. Spitzer observations of acetylene bands in carbon-rich AGB stars in the Large Magellanic Cloud

    CERN Document Server

    Matsuura, M; Sloan, G C; Zijlstra, A A; Van Loon, J T; Groenewegen, M A T; Blommaert, J A D L; Cioni, M R L; Feast, M W; Habing, H J; Hony, S; Lagadec, E; Loup, C; Menzies, J W; Waters, L B F M; Whitelock, P A

    2006-01-01

    We investigate the molecular bands in carbon-rich AGB stars in the Large Magellanic Cloud (LMC), using the InfraRed Spectrograph (IRS) on board the Spitzer Space Telescope (SST) over the 5--38 micron range. All 26 low-resolution spectra show acetylene (C2H2) bands at 7 and 14 micron. The hydrogen cyanide (HCN) bands at these wavelengths are very weak or absent. This is consistent with low nitrogen abundances in the LMC. The observed 14 micron C2H2 band is reasonably reproduced by an excitation temperature of 500 K. There is no clear dilution of the 14 micron band by circumstellar dust emission. This 14 micron band originates from molecular gas in the circumstellar envelope in these high mass-loss rate stars, in agreement with previous findings for Galactic stars. The C2H2,column density, derived from the 13.7 micron band, shows a gas mass-loss rate in the range 3x10^-6 to 5x10^{-5} Msun yr-1. This is comparable with the total mass-loss rate of these stars estimated from the spectral energy distribution. Addit...

  9. DFT study of selective hydrogenation of acetylene to ethylene on Pd doping Ag nanoclusters

    Science.gov (United States)

    Liu, D.

    2016-11-01

    Recently, it has been reported that the reaction selectivity of catalytic hydrogenation of acetylene to ethylene can be significantly enhanced via the approach of Pd mono-atomic catalysis [Pei et al. ACS Catal. 5 (2015) 3717-3725]. To explain the catalytic mechanism of this binary alloy catalyst, C2H2 hydrogenation reactions on Pd doping Ag nanoclusters are studied using density functional theory simulations. The simulation results indicate that H2 and C2H2 can simultaneously bind with a single Pd doping atom no matter it is on vertex and edge sites of Ag clusters. The following H2 dissociation and C2H2 hydrogenation are not difficult since the corresponding reaction barrier values are no more than 0.58 eV. The generated C2H4 molecule can not be further hydrogenated since it locates on the top of Pd doping atom, which is the only adsorption site for H2. On two Pd doping atoms at contiguous sites of Ag clusters, C2H4 hydrogenation reactions can be carried out since there are enough sites for co-adsorption of H2 and C2H4.

  10. Picosecond phase conjugation in two-photon absorption in poly-di-acetylenes

    International Nuclear Information System (INIS)

    Poly-di-acetylenes exhibit a large two-photon absorption at 1064 nm wavelength. Its different effects on phase-conjugate nonlinearity are described in the framework of picosecond experiments. In solutions, gels, and films (optically thin media), third-order susceptibility appears as an increasing intensity dependent function. Phase measurements by nonlinear interferometry with the substrate or with the solvent are compared with predictions of a resonantly driven three level system. Phase-conjugate response exhibits a multi-exponential decay. Polarization symmetries analysis shows a one-dimensional effect. Study under strong static electric field action reveals that we face charged species bound to photoconductive polymer chains. In PTS single crystals (optically thick media), response saturates and cancels at high light intensity. This is well accounted for by propagation equations solved in large two-photon absorption conditions. The effect is exploited in a phase conjugation experiment under external optical pump excitation. We thus demonstrate that enhanced nonlinearity is a two-photon absorption relayed and amplified by mid-gap absorbing species which have been created by this two-photon absorption. We formally face a four-photon absorption described by a positive imaginary seventh-order non-linearity. (author)

  11. Chromophores from photolyzed ammonia reacting with acetylene: Application to Jupiter's Great Red Spot

    Science.gov (United States)

    Carlson, R. W.; Baines, K. H.; Anderson, M. S.; Filacchione, G.; Simon, A. A.

    2016-08-01

    The high altitude of Jupiter's Great Red Spot (GRS) may enhance the upward flux of gaseous ammonia (NH3) into the high troposphere, where NH3 molecules can be photodissociated and initiate a chain of chemical reactions with downwelling acetylene molecules (C2H2). These reactions, experimentally studied earlier by (Ferris and Ishikawa [1987] Nature 326, 777-778) and (Ferris and Ishikawa [1988] J. Amer. Chem. Soc. 110, 4306-4312), produce chromophores that absorb in the visible and ultraviolet regions. In this work we photolyzed mixtures of NH3 and C2H2 using ultraviolet radiation with a wavelength of 214 nm and measured the spectral transmission of the deposited films in the visible region (400-740 nm). From these transmission data we estimated the imaginary indices of refraction. Assuming that ammonia grains at the top of the GRS clouds are coated with this material, we performed layered sphere and radiative transfer calculations to predict GRS reflection spectra. Comparison of those results with observed and previously unreported Cassini visible spectra and with true-color images of the GRS show that the unknown GRS chromophore is spectrally consistent with the coupled NH3-C2H2 photochemical products produced in our laboratory experiments. Using high-resolution mass spectrometry and infrared spectroscopy we infer that the chromophore-containing residue is composed of aliphatic azine, azo, and diazo compounds.

  12. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

    CERN Document Server

    Courtney, Michael

    2011-01-01

    Instrumentation is needed to produce realistic blast waves in a laboratory setting. This paper describes the development and characterization of oxy-acetylene driven, laboratory scale shock tubes for use in studying blast injury, candidate armor materials, and material properties at blast loading rates. The pressure-time profiles show a true shock front and exponential decay characteristic of blast waves and have relevant durations. The modular design includes shock tube diameters of 27 mm and 41 mm, and a selection of peak pressures from 204 kPa to 920 kPa can be produced by selection of the driver section diameter and placement of the test sample. Characterization studies of several driver/driven section combinations showed consistent results, with peak pressures having 0.8 - 6.9 percent uncertainty in the mean. This shock tube design provides a more realistic blast profile than current air-driven shock tubes. In addition, operation does not require specialized personnel or facilities like most blast-driven...

  13. Chromophores from photolyzed ammonia reacting with acetylene: Application to Jupiters Great Red Spot

    Science.gov (United States)

    Carlson, Robert W.; Baines, Kevin H.; Anderson, M. S.; Filacchione, G.; Simon, A. A.

    2016-01-01

    The high altitude of Jupiter's Great Red Spot (GRS) may enhance the upward flux of gaseous ammonia (NH3 ) into the high troposphere, where NH3 molecules can be photodissociated and initiate a chain of chemical reactions with downwelling acetylene molecules (C2H2 ). These reactions, experimentally studied earlier by (Ferris and Ishikawa [1987] Nature 326, 777-778) and (Ferris and Ishikawa [1988] J. Amer. Chem. Soc. 110, 4306-4312), produce chromophores that absorb in the visible and ultraviolet regions. In this work we photolyzed mixtures of NH3 and C2H2 using ultraviolet radiation with a wavelength of 214 nm and measured the spectral transmission of the deposited films in the visible region (400-740 nm). From these transmission data we estimated the imaginary indices of refraction. Assuming that ammonia grains at the top of the GRS clouds are coated with this material, we performed layered sphere and radiative transfer calculations to predict GRS reflection spectra. Comparison of those results with observed and previously unreported Cassini visible spectra and with true-color images of the GRS show that the unknown GRS chromophore is spectrally consistent with the coupled NH3-C2H2 photochemical products produced in our laboratory experiments. Using high-resolution mass spectrometry and infrared spectroscopy we infer that the chromophore-containing residue is composed of aliphatic azine, azo, and diazo compounds.

  14. Zwitterionic Surfactant Modified Acetylene Black Paste Electrode for Highly Facile and Sensitive Determination of Tetrabromobisphenol A

    Directory of Open Access Journals (Sweden)

    Xiaoyun Wei

    2016-09-01

    Full Text Available A electrochemical sensor for the highly sensitive detection of tetrabromobisphenol A (TBBPA was fabricated based on acetylene black paste electrode (ABPE modified with 3-(N,N-Dimethylpalmitylammonio propanesulfonate (SB3-16 in this study. The peak current of TBBPA was significantly enhanced at SB3-16/ABPE compared with unmodified electrodes. To further improve the electrochemical performance of the modified electrode, corresponding experimental parameters such as the length of hydrophobic chains of zwitterionic surfactant, the concentration of SB3-16, pH value, and accumulation time were examined. The peak currents of TBBPA were found to be linearly correlated with its concentrations in the range of 1 nM to 1 µM, with a detection limit of 0.4 nM. Besides, a possible mechanism was also discussed, and the hydrophobic interaction between TBBPA and the surfactants was suggested to take a leading role in enhancing the responses. Finally, this sensor was successfully employed to detect TBBPA in water samples.

  15. Global modeling of vibration-rotation spectra of the acetylene molecule

    Science.gov (United States)

    Lyulin, O. M.; Perevalov, V. I.

    2016-07-01

    The global modeling of both line positions and intensities of the acetylene molecule in the 50-9900 cm-1 region has been performed using the effective operators approach. The parameters of the polyad model of effective Hamiltonian have been fitted to the line positions collected from the literature. The used polyad model of effective Hamiltonian takes into account the centrifugal distortion, rotational and vibrational ℓ-doubling terms and both anharmonic and Coriolis resonance interaction operators arising due to the approximate relations between the harmonic frequencies: ω1≈ω3≈5ω4≈5ω5 and ω2≈3ω4≈3ω5. The dimensionless weighted standard deviation of the fit is 2.8. The fitted set of 237 effective Hamiltonian parameters allowed reproducing 24,991 measured line positions of 494 bands with a root mean squares deviation 0.0037 cm-1. The eigenfunctions of the effective Hamiltonian corresponding to the fitted set of parameters were used to fit the observed line intensities collected from the literature for 15 series of transitions: ΔP = 0-13,15, where P=5V1+5V3 +3V2+V4+V5 is the polyad number (Vi are the principal vibrational quantum numbers). The fitted sets of the effective dipole moment parameters reproduce the observed line intensities within their experimental uncertainties 2-20%.

  16. Analysis of the influence of various effects on frequency shifts of the acetylene saturated absorption lines

    Institute of Scientific and Technical Information of China (English)

    Dong Lei; Zhang Lei; Dou Hai-Peng; Yin Wang-Bao; Jia Suo-Tang

    2008-01-01

    Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature,gas pressure and laser power have been investigated in detail.The second-order Doppler effect,the recoil effect,the Zeeman effect,the pressure shift and the power shift are taken into consideration.The magnitudes of those shifts caused by various effects are evaluated.In order to reproduce the stability of 5.7 x 10-14 obtained by Edwards,all necessary conditions are given.The results show that when there is a larger external magnetic field,the Zeeman shift could not be neglected,so that the shield should be employed.And the design of a long cavity is advantageous to reduce the influence of the second-order Doppler effect.The results also show that at least ±2.5°C temperature control for cavity can effectively prevent several effects and improve the frequency stability.

  17. Antitrypanosomal Acetylene Fatty Acid Derivatives from the Seeds of Porcelia macrocarpa (Annonaceae).

    Science.gov (United States)

    de Á Santos, Luciana; Cavalheiro, Alberto J; Tempone, Andre G; Correa, Daniela S; Alexandre, Tatiana R; Quintiliano, Natalia F; Rodrigues-Oliveira, André F; Oliveira-Silva, Diogo; Martins, Roberto Carlos C; Lago, João Henrique G

    2015-05-07

    Chagas' disease is caused by a parasitic protozoan and affects the poorest population in the world, causing high mortality and morbidity. As a result of the toxicity and long duration of current treatments, the discovery of novel and more efficacious drugs is crucial. In this work, the hexane extract from seeds of Porcelia macrocarpa R.E. Fries (Annonaceae) displayed in vitro antitrypanosomal activity against trypomastigote forms of T. cruzi by the colorimetric MTT assay (IC50 of 65.44 μg/mL). Using chromatographic fractionation over SiO2, this extract afforded a fraction composed by one active compound (IC50 of 10.70 µg/mL), which was chemically characterized as 12,14-octadecadiynoic acid (macrocarpic acid). Additionally, two new inactive acetylene compounds (α,α'-dimacro-carpoyl-β-oleylglycerol and α-macrocarpoyl-α'-oleylglycerol) were also isolated from the hexane extract. The complete characterization of the isolated compounds was performed by analysis of NMR and MS data as well as preparation of derivatives.

  18. Antitrypanosomal Acetylene Fatty Acid Derivatives from the Seeds of Porcelia macrocarpa (Annonaceae

    Directory of Open Access Journals (Sweden)

    Luciana de Á. Santos

    2015-05-01

    Full Text Available Chagas’ disease is caused by a parasitic protozoan and affects the poorest population in the world, causing high mortality and morbidity. As a result of the toxicity and long duration of current treatments, the discovery of novel and more efficacious drugs is crucial. In this work, the hexane extract from seeds of Porcelia macrocarpa R.E. Fries (Annonaceae displayed in vitro antitrypanosomal activity against trypomastigote forms of T. cruzi by the colorimetric MTT assay (IC50 of 65.44 μg/mL. Using chromatographic fractionation over SiO2, this extract afforded a fraction composed by one active compound (IC50 of 10.70 µg/mL, which was chemically characterized as 12,14-octadecadiynoic acid (macrocarpic acid. Additionally, two new inactive acetylene compounds (α,α'-dimacro-carpoyl-β-oleylglycerol and α-macrocarpoyl-α'-oleylglycerol were also isolated from the hexane extract. The complete characterization of the isolated compounds was performed by analysis of NMR and MS data as well as preparation of derivatives.

  19. SMFs-supported Pd nanocatalysts in selective acetylene hydrogenation:Pore structure-dependent deactivation mechanism

    Institute of Scientific and Technical Information of China (English)

    Elaheh; Esmaeili; Ali; Morad; Rashidi; Yadollah; Mortazavi; Abbas; Ali; Khodadadi; Mehdi; Rashidzadeh

    2013-01-01

    In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.

  20. Conformations of propargyl alcohol and its interaction with acetylene: A matrix isolation infrared and DFT computations

    Science.gov (United States)

    Sundararajan, K.; Gopi, R.; Ramanathan, N.

    2016-10-01

    Conformations of propargyl alcohol (PA) were studied using matrix isolation infrared spectroscopy. DFT computations using 6-311++G(d,p) basis set on the PA molecule identified two minima; gauche (g-PA) and trans (t-PA). Comparison of infrared spectra of PA trapped in Ar, N2 and Xe matrices with computations showed the evidence of the ground state g-PA conformer. Four minima were optimized on the potential energy surface for the hydrogen-bonded interaction of g-PA and acetylene (C2H2), corresponding to complex A (Csbnd H⋯O), complex B (Osbnd H⋯π) and complex C and D (Csbnd H⋯π). The structure, energies and the vibrational wavenumbers were computed for these complexes at B3LYP/6-311++G (d,p) level of theory. The infrared spectra of the hydrogen-bonded complexes between C2H2 and g-PA were studied in Ar matrix. The infrared spectra recorded under matrix isolation conditions revealed the formation of two types of complexes A (Csbnd H⋯O) and B (Osbnd H⋯π). Formation of these complexes was evidenced from the shifts in the vibrational wavenumber of the modes involving the C2H2 and PA submolecules.

  1. Using Acetylene for Selective Catalytic Reduction of NO in Excess Oxygen

    Institute of Scientific and Technical Information of China (English)

    YU Shan-Shan; WANG Xin-Ping; WANG Chong; XU Yan

    2006-01-01

    Acetylene as a reducing agent for selective catalytic reduction of NO (C2H2-SCR) was investigated over a series of metal exchanged HY catalysts, in the reaction system of 0.16% NO, 0.08% C2H2, and 9.95% O2 (volume percent)in He. 75% of NO conversion to N2 with hydrocarbon efficiency about 1.5 was achieved over a Ce-HY catalyst around 300 ℃. The NO removal level was comparable with that of selective catalytic reduction of NOx by C3H6reported in literatures, although only one third of the reducing agent in carbon moles was used in the C2H2-SCR of NO. The protons in zeolite were crucial to the C2H2-SCR of NO, and the performance of HY in the reaction was significantly promoted by cerium incorporation into the zeolite. NO2 was proposed to be the intermediate of NO reduction to N2, and the oxidation of NO to NO2 was rate-determining step of the C2H2-SCR of NO over Ce-HY.The suggestion was well supported by the results of the NO oxidation with O2, and the C2H2 consumption under the conditions in the presence or absence of NO.

  2. Zwitterionic Surfactant Modified Acetylene Black Paste Electrode for Highly Facile and Sensitive Determination of Tetrabromobisphenol A

    Science.gov (United States)

    Wei, Xiaoyun; Zhao, Qiang; Wu, Weixiang; Zhou, Tong; Jiang, Shunli; Tong, Yeqing; Lu, Qing

    2016-01-01

    A electrochemical sensor for the highly sensitive detection of tetrabromobisphenol A (TBBPA) was fabricated based on acetylene black paste electrode (ABPE) modified with 3-(N,N-Dimethylpalmitylammonio) propanesulfonate (SB3-16) in this study. The peak current of TBBPA was significantly enhanced at SB3-16/ABPE compared with unmodified electrodes. To further improve the electrochemical performance of the modified electrode, corresponding experimental parameters such as the length of hydrophobic chains of zwitterionic surfactant, the concentration of SB3-16, pH value, and accumulation time were examined. The peak currents of TBBPA were found to be linearly correlated with its concentrations in the range of 1 nM to 1 µM, with a detection limit of 0.4 nM. Besides, a possible mechanism was also discussed, and the hydrophobic interaction between TBBPA and the surfactants was suggested to take a leading role in enhancing the responses. Finally, this sensor was successfully employed to detect TBBPA in water samples. PMID:27657078

  3. In situ acetylene reduction activity of Scytonema julianum in Vapor cave (Spain

    Directory of Open Access Journals (Sweden)

    Asencio Antonia Dolores

    2011-01-01

    Full Text Available Nitrogen fixation was measured in situ for the first time by acetylene reduction for a greyish mat composed of Scytonema julianum in cave- like environments. Mat-specific rates (129.9-215.7 nmol C2 H4 m-2 s-1 for daytime fixation and 65.1-120.6 nmol C2 H4 m-2 s-1 for nighttime fixation recorded in the Vapor cave differed considerably due to the energy reserves stored during photosynthesis being exhausted and used in the dark phase. The most influential environmental parameter for nitrogen fixation in the Vapor cave is temperature in the daytime and nighttime fixations. Nitrogen fixation by cyanobacteria may contribute considerably to the overall nitrogen cycle in harsh environments such as caves. Nitrogenase activity in Scytonema julianum was roughly 30 times higher than that of Scytonema mirabile, which also grew in cave environments, which is due to the characteristics of each site. The entrance of Vapour cave (Spain faces SE, measures 0.75 x 0.6 m and opens to shafts of a total depth of 80 m. Its dimensions and environmental conditions (relative humidity up to 100%; maximum temperature, 43oC imply that it is isolated from external influences, and that the microclimate differs substantially from that experienced externally. Nitrogen fixation, photon flux density, relative humidity and temperature in the Vapor cave were taken hourly over a 24-hour period in winter.

  4. Surface characterization of the interfaces from plasma-polymerized acetylene films deposited onto cold-rolled steel for rubber-to-metal bonding

    Science.gov (United States)

    Rosales Lombardi, Pablo I.

    The molecular structure of the interface between plasma-polymerized acetylene films and steel was determined using in-situ reflection-absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS). Plasma-polymerized acetylene films were deposited onto polished steel substrates in microwave (MW) and radio frequency (RF)-powered reactors. The films deposited in RF-powered reactors were characterized in-situ using XPS and FTIR spectrometers that were interfaced directly to the reactors. RAIR showed that the plasma polymerized films contained large numbers of methyl and methylene groups but only a small number of monosubstituted acetylene groups, indicating that there was substantial rearrangement of the monomer molecules during plasma polymerization. The rearrangement of the monomer molecules during plasma was also determined by optical emission spectroscopy (OES), where CH and C2 species predominated in the optical emission spectra. Bands were observed near 1020 and 885 cm-1 in the RAIR spectra that were attributed to skeletal stretching vibrations in C-C-O-Fe groups, indicating that the plasma-polymerized films interacted with the substrate through formation of alkoxide bonds. Another band was observed near 1565 cm-1 and attributed to carboxylate groups in the interface between films and the oxidized surface of the substrate. Results from XPS also confirmed the formation of alkoxide and carboxylate groups in the interface during plasma polymerization of acetylene. Results from XPS showed that the surface of steel substrates consisted mostly of a mixture of Fe2O3 and FeOOH and that iron was mostly present in the Fe(III) oxidation state. However, during plasma-polymerization of acetylene, there was a tendency for the concentration of Fe(II) to increase, due to the reducing nature of argon/acetylene plasmas. Natural rubber reacted with plasma-polymerized acetylene primers through unsaturated functional groups present in the film. The RAIR and XPS

  5. Intramolecular competition between n-pair and π-pair hydrogen bonding: Microwave spectrum and internal dynamics of the pyridine–acetylene hydrogen-bonded complex

    International Nuclear Information System (INIS)

    a-type rotational spectra of the hydrogen-bonded complex formed from pyridine and acetylene are reported. Rotational and 14N hyperfine constants indicate that the complex is planar with an acetylenic hydrogen directed toward the nitrogen. However, unlike the complexes of pyridine with HCl and HBr, the acetylene moiety in HCCH—NC5H5 does not lie along the symmetry axis of the nitrogen lone pair, but rather, forms an average angle of 46° with the C2 axis of the pyridine. The a-type spectra of HCCH—NC5H5 and DCCD—NC5H5 are doubled, suggesting the existence of a low lying pair of tunneling states. This doubling persists in the spectra of HCCD—NC5H5, DCCH—NC5H5, indicating that the underlying motion does not involve interchange of the two hydrogens of the acetylene. Single 13C substitution in either the ortho- or meta-position of the pyridine eliminates the doubling and gives rise to separate sets of spectra that are well predicted by a bent geometry with the 13C on either the same side (“inner”) or the opposite side (“outer”) as the acetylene. High level ab initio calculations are presented which indicate a binding energy of 1.2 kcal/mol and a potential energy barrier of 44 cm−1 in the C2v configuration. Taken together, these results reveal a complex with a bent hydrogen bond and large amplitude rocking of the acetylene moiety. It is likely that the bent equilibrium structure arises from a competition between a weak hydrogen bond to the nitrogen (an n-pair hydrogen bond) and a secondary interaction between the ortho-hydrogens of the pyridine and the π electron density of the acetylene

  6. Intersystem Communications between Virtualized Agents

    Directory of Open Access Journals (Sweden)

    Ovidiu Gherman

    2015-12-01

    Full Text Available This paper presents an analysis of the main problems associated with data and command communications in virtualized environments. This aspect is very important in determining the performance and functionality of such systems. In this regard, an effective data communication brings obvious advantages for volume data transfer (images, backups, checkpointing information. If we are to refer to resource administration overhead, we can notice that direct connectivity - although important - is not the only factor which defines the performance of data transfers; resource administration, resource loading and load balancing are also extremely important. Furthermore, a command structure is very important to expand the capabilities of underlying software (platform. Even if a platform supports various functions, the system should have the capability to discover, asses, command, deploy and monitor various dynamic virtualized resources in order to correctly (and efficiently use those resources, either via predefined protocols or via a set of mission-defined parameters that are transferred and intelligently parsed and processed.

  7. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects.

    Science.gov (United States)

    Courtney, Amy C; Andrusiv, Lubov P; Courtney, Michael W

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile. PMID:22559580

  8. Concentration Dependence of Line Shapes in the ν_1 + ν_3 Band of Acetylene

    Science.gov (United States)

    Cich, Matthew; Forthomme, Damien; Hall, Gregory; McRaven, C.; Sears, Trevor

    2014-06-01

    Using an extended cavity diode laser locked to a frequency comb, the line shape of the P(11) line in the ν_1 + ν_3 combination band of acetylene has been studied as a function of varying concentration of the absorber in nitrogen. Mixture concentrations of 1, 5 and 10% at 296 K and pressures between a few Torr and one atmosphere were made and the measurements analyzed using two different speed-dependent broadening models. These experiments are designed to test the additivity of contributions to pressure broadening and shift in speed-dependent line shape modeling, i.e. whether the lineshape parameters follow partial pressure weighting in the binary mixtures. P(11) is relatively isolated with respect to underlying hot band transitions and neighboring transitions of the same band, but it was found that the accurate positions of underlying hot band transitions were crucial to the successful modeling of the observed line shapes, even though these lines are typically 100-1000 times weaker than P(11) itself and are many Doppler line widths removed from the line center. Positions of the hot band lines quoted in the HITRAN database, which are derived from the analysis of high resolution FTIR spectra, are of the order of 10's of MHz in error. In parallel work, we have measured the positions of many of these lines by saturation dip spectroscopy. Progress in the analysis of the data and the new saturation dip line center measurements will be reported. [1] C. P. McRaven, et al. Paper RI05, 68th International Symposium on Molecular Spectroscopy, 2013 Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

  9. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    Science.gov (United States)

    Karhu, J.; Nauta, J.; Vainio, M.; Metsälä, M.; Hoekstra, S.; Halonen, L.

    2016-06-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν 1 + ν 2 + ν 3 + ν4 1 + ν5 - 1 in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm-1, the rotational parameter B was 1.162 222(37) cm-1, and the quartic centrifugal distortion parameter D was 3.998(62) × 10-6 cm-1, where the numbers in the parenthesis are one-standard errors in the least significant digits.

  10. Measurement of cardiac output during exercise by open-circuit acetylene uptake.

    Science.gov (United States)

    Barker, R C; Hopkins, S R; Kellogg, N; Olfert, I M; Brutsaert, T D; Gavin, T P; Entin, P L; Rice, A J; Wagner, P D

    1999-10-01

    Noninvasive measurement of cardiac output (QT) is problematic during heavy exercise. We report a new approach that avoids unpleasant rebreathing and resultant changes in alveolar PO(2) or PCO(2) by measuring short-term acetylene (C(2)H(2)) uptake by an open-circuit technique, with application of mass balance for the calculation of QT. The method assumes that alveolar and arterial C(2)H(2) pressures are the same, and we account for C(2)H(2) recirculation by extrapolating end-tidal C(2)H(2) back to breath 1 of the maneuver. We correct for incomplete gas mixing by using He in the inspired mixture. The maneuver involves switching the subject to air containing trace amounts of C(2)H(2) and He; ventilation and pressures of He, C(2)H(2), and CO(2) are measured continuously (the latter by mass spectrometer) for 20-25 breaths. Data from three subjects for whom multiple Fick O(2) measurements of QT were available showed that measurement of QT by the Fick method and by the C(2)H(2) technique was statistically similar from rest to 90% of maximal O(2) consumption (VO(2 max)). Data from 12 active women and 12 elite male athletes at rest and 90% of VO(2 max) fell on a single linear relationship, with O(2) consumption (VO(2)) predicting QT values of 9.13, 15.9, 22.6, and 29.4 l/min at VO(2) of 1, 2, 3, and 4 l/min. Mixed venous PO(2) predicted from C(2)H(2)-determined QT, measured VO(2), and arterial O(2) concentration was approximately 20-25 Torr at 90% of VO(2 max) during air breathing and 10-15 Torr during 13% O(2) breathing. This modification of previous gas uptake methods, to avoid rebreathing, produces reasonable data from rest to heavy exercise in normal subjects. PMID:10517785

  11. Infrared analysis of soot produced from an acetylene-rich flame

    Science.gov (United States)

    Pino, Thomas; Dartois, Emmanuel; Cao, Anh Tuan; D'Hendecourt, Louis; Bréchignac, Philippe

    The ubiquitous unidentified infrared emission bands (UIBs), now referred to as aromatic infrared bands (AIBs), observed from a variety of regions of interstellar space have been recognized to involve carbonaceous material with an aromatic character. It is now widely accepted that these interstellar "nanograins" should have sizes intermediate between those of the PAHs easily accessible to laboratory studies and of the "standard" interstellar grains (ca 0.05μm or 50 nm). The nanometer size is related to their capability of being transiently heated upon absorption of UV starlight photons. We will present the preliminary results obtained with a new experimental set-up, devoted to the formation of carbonaceous nanoparticles and the characterization of their spectral properties in absorption and in emission, in the solid phase and in the gas phase, isolated in a van der Waals matrix or free-flying. The production of the species uses laboratory techniques and conditioning under specific interstellar processes such as coupling a chemical reactor to stellar-like UV irradiation. We have used in particular an acetylene-rich, premixed and flat, low-pressure flame as a reactor. When operated under low-pressure conditions, the spatial development of the flame allows us to sample its content at various stages of the particles growth. The analysis can be made by transmission spectroscopy of thin film deposits under infrared microscope or in rare gas matrices under FTIR spectroscopy, and by Time-Of-Flight mass spectrometry. The preliminary results reveal a strong evolution from aromatic materials containing aliphatic substituents to large polymer-like soot particules. The spectrum in Figure 1 is that of a deposition taken from a sooting flame at a C/O=2, burning at a pressure of 26.5mb, and sampled at 12mm from the flat burner. A tentative assignment is given.

  12. Selective hydrogenation of acetylene on SiO2 supported Ni-In bimetallic catalysts: Promotional effect of In

    Science.gov (United States)

    Chen, Yanjun; Chen, Jixiang

    2016-11-01

    Ni/SiO2 and the bimetallic NixIn/SiO2 catalysts with different Ni/In ratios were tested for the selective hydrogenation of acetylene, and their physicochemical properties before and after the reaction were characterized by means of N2-sorption, H2-TPR, XRD, TEM, XPS, H2 chemisorption, C2H4-TPD, NH3-TPD, FT-IR of adsorbed pyridine, and TG/DTA and Raman. A promotional effect of In on the performance of Ni/SiO2 was found, and NixIn/SiO2 with a suitable Ni/In ratio gave much higher acetylene conversion, ethylene selectivity and catalyst stability than Ni/SiO2. This is ascribed to the geometrical isolation of the reactive Ni atoms with the inert In ones and the charge transfer from the In atoms to Ni ones, both of which are favorable for reducing the adsorption strength of ethylene and restraining the Csbnd C hydrogenolysis and the polymerizations of acetylene and the intermediate compounds. On the whole, Ni6In/SiO2 and Ni10In/SiO2 had better performance. Nevertheless, with increasing the In content, the selectivity to the C4+ hydrocarbons tended to increase due to the enhanced catalyst acidity because of the charge transfer from the In atoms to Ni ones. As the Lewis acid ones, the In sites could promote the polymerization. The catalyst deactivation was also analyzed. We propose that the Ni/SiO2 deactivation is mainly attributed to the phase change from metallic Ni to nickel carbide. The introduction of In inhibited the formation of nickel carbide. However, as the In content increased, the carbonaceous deposit became the main reason for the NixIn/SiO2 deactivation due to the enhanced catalyst acidity.

  13. Acetylene hydratase: a non-redox enzyme with tungsten and iron-sulfur centers at the active site.

    Science.gov (United States)

    Kroneck, Peter M H

    2016-03-01

    In living systems, tungsten is exclusively found in microbial enzymes coordinated by the pyranopterin cofactor, with additional metal coordination provided by oxygen and/or sulfur, and/or selenium atoms in diverse arrangements. Prominent examples are formate dehydrogenase, formylmethanofuran dehydrogenase, and aldehyde oxidoreductase all of which catalyze redox reactions. The bacterial enzyme acetylene hydratase (AH) stands out of its class as it catalyzes the conversion of acetylene to acetaldehyde, clearly a non-redox reaction and a reaction distinct from the reduction of acetylene to ethylene by nitrogenase. AH harbors two pyranopterins bound to W, and a [4Fe-4S] cluster. W is coordinated by four dithiolene sulfur atoms, one cysteine sulfur, and one oxygen ligand. AH activity requires a strong reductant suggesting W(IV) as the active oxidation state. Two different types of reaction pathways have been proposed. The 1.26 Å structure reveals a water molecule coordinated to W which could gain a partially positive net charge by the adjacent protonated Asp-13, enabling a direct attack of C2H2. To access the W-Asp site, a substrate channel was evolved distant from where it is found in other members of the DMSOR family. Computational studies of this second shell mechanism led to unrealistically high energy barriers, and alternative pathways were proposed where C2H2 binds directly to W. The architecture of the catalytic cavity, the specificity for C2H2 and the results from site-directed mutagenesis do not support this first shell mechanism. More investigations including structural information on the binding of C2H2 are needed to present a conclusive answer. PMID:26790879

  14. Morphology of carbon nanotubes prepared via chemical vapour deposition technique using acetylene: A small angle neutron scattering investigation

    Indian Academy of Sciences (India)

    D Sen; K Dasgupta; J Bahadur; S Mazumder; D Sathiyamoorthy

    2008-11-01

    Small angle neutron scattering (SANS) has been utilized to study the morphology of the multi-walled carbon nanotubes prepared by chemical vapour deposition of acetylene. The effects of various synthesis parameters like temperature, catalyst concentration and catalyst support on the size distribution of the nanotubes are investigated. Distribution of nanotube radii in two length scales has been observed. The number density of the smaller diameter tubes was found more in number compared to the bigger one for all the cases studied. No prominent scaling of the structure factor was observed for the different synthesis conditions.

  15. Measurement of ethylene and methane production in a temperate forest soil using inhibition of acetylene and carbon monoxide

    Institute of Scientific and Technical Information of China (English)

    XU XingKai; INUBUSHI Kazuyuki

    2008-01-01

    We studied in the laboratory the effects of acetylene (C2H2) concentrations on the accumulation and consumption of ethylene and methane in a temperate pine forest soil, and in situ ethylene and methane production and flush effects of nitrogen sources on both productions in the pine forest stand (Pinus sylvestris L.). The addition of C2H2 at concentrations more than 50 Pa C2H2 in the headspace caused a more than 95% reduction in rates of ethylene and methane consumption in forest soil compared to those with no C2H2. Furthermore, addition of acetylene within a range of 50 to 10, 000 Pa C2H2 induced a similar rate of methane accumulation in forest soil. Hence, it can be concluded that presence of more than 50 Pa C2H2 in the headspace is an effective method to measure methane production in forest soil. The addition of C2H2 at concentrations more than 50 Pa C2H2 induced an increasing concentration of ethylene in the headspace (P≤0.05), indicating the reduction of acetylene to ethylene in forest soil. Using inhibition of 0.5 kPa C2H2 in combination with 5 kPa carbon monoxide that inhibits the reduction of acetylene in a short term, it was observed that there was a larger in situ methane production rate (218±26 μg C m-2 h-1 (μg C per square meter per hour, the same below)) than in situethylene produc-tion rate (92 ± 6 μg C m-2 h-1) in the pine forest soil. The addition of nitrogen sources such as urea, urea plus a nitrification inhibitor dicyandiamide, and potassium nitrate, could induce a 5-fold greater in-crease in rates of in situ ethylene and methane production compared to those in the control, particu-larly in the latter (P≤0.05). The results can promote in situ measurement of ethylene and methane production in forest soils at different sites.

  16. Designing supported palladium-on-gold bimetallic nano-catalysts for controlled hydrogenation of acetylene in large excess of ethylene

    Science.gov (United States)

    Malla, Pavani

    Ethylene is used as a starting point for many chemical intermediates in the petrochemical industry. It is predominantly produced through steam cracking of higher hydrocarbons (ethane, propane, butane, naphtha, and gas oil). During the cracking process, a small amount of acetylene is produced as a side product. However, acetylene must be removed since it acts as a poison for ethylene polymerization catalysts at even ppm concentrations (>5 ppm). Thus, the selective hydrogenation of acetylene to ethylene is an important process for the purification of ethylene. Conventional, low weight loading Pd catalysts are used for this selective reaction in high concentration ethylene streams. Gold was initially considered to be catalytically inactive for a long time. This changed when gold was seen in the context of the nanometric scale, which has indeed shown it to have excellent catalytic activity as a homogeneous or a heterogeneous catalyst. Gold is proved to have high selectivity to ethylene but poor at conversion. Bimetallic Au and Pd catalysts have exhibited superior activity as compared to Pd particles in semi-hydrogenation. Hydrogenation of acetylene was tested using this bimetallic combination. The Pd-on-Au bimetallic catalyst structure provides a new synthesis approach in improving the catalytic properties of monometallic Pd materials. TiO 2 as a support material and 0.05%Pd loading on 1%Au on titania support and used different treatment methods like washing plasma and reduction between the two metal loadings and was observed under 2:1 ratio. In my study there were two set of catalysts which were prepared by a modified incipient wetness impregnation technique. Out of all the reaction condition the catalyst which was reduced after impregnating gold and then impregnating palladium which was further treated in non-thermal hydrogen plasma and then pretreated in hydrogen till 250°C for 1 hour produced the best activity of 76% yield at 225°C. Stability tests were conducted

  17. Nuclear magnetic resonance study of the structure of simple molecules adsorbed on metal surfaces: acetylene on platinum

    International Nuclear Information System (INIS)

    We have used NMR to determine the structure of acetylene (HC - CH) adsorbed at room temperature on small platinum particles by studying the 13C-13C, 13C-1H, and 1H-1H dipolar interactions among the nuclei in the adsorbed molecules. We find a model of 77% CCH2 and 23% HCCH to be the only one consistent with all of our data. The C-C bond length of the majority species, CCH2, is determined as 1.44 +- 0.02 A, midway between a single and double bond, suggesting that both carbon atoms bond to the surface. 36 references, 29 figures, 1 table

  18. El cieno de acetileno como tratamiento de la tricofitosis de los terneros-(Acetylene mud as tricophytosis treatment in calves.

    Directory of Open Access Journals (Sweden)

    Hernández Barreto, Miguel A

    2011-04-01

    Full Text Available ResumenLa tricofitosis es una enfermedad micótica que afecta a numerosas especies animales, incluyendo al hombre. Los tratamientos utilizados para combatir esta entidad son numerosos e incluyen antimicóticos, vacunas y desinfectantes.SummaryTricophytosis is a mycotic disease that affects numerous animal species, including man. The treatments used to combat this entity are numerous and include antimycotics, vaccines and disinfectants. In our work we use acetylene mud paste made from waste carbide (industrial residual as topical treatment in dermatomycoses lesions in calves (group I, study, comparing the results with cooper sulfate dissolution 22% (group II, control.

  19. Upconversion enhanced degenerate four-wave mixing in the mid-infrared for sensitive detection of acetylene in gas flows

    DEFF Research Database (Denmark)

    Høgstedt, Lasse; Dam, Jeppe Seidelin; Sahlberg, Anna-Lena;

    2014-01-01

    We present a new background free method for in situ gas detection that combines degenerate four-wave mixing with an infra-red light detector based on parametric frequency upconversion of infra-red light. The system is demonstrated at mid infrared wavelengths for low concentration measurements...... of acetylene diluted in a N2 gas flow at ambient conditions. It is demonstrated that the system is able to cover more than 100 nm in scanning range and detect concentrations as low as 3 ppm based on the R9e line. A major issue in small signal measurements is scattered light and it is showed how a spatial...

  20. Temperature dependence of corrosion inhibition of steels used in oil well stimulation using acetylenic compound and halide ion salt mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Menezes, M.A.M. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica], E-mail: marcom@eq.ufrj.br; Valle, M.L.M. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica. Dept. de Processos Organicos; Dweck, J. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica. Dept. de Processos Inorganicos; Queiroz Neto, J.C. [Petroleo Brasileiro S.A. (CENPES / PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2007-07-15

    Halogenated salt (HS)-acetylenic compound (AC) mixtures were tested as corrosion inhibitors of 13Cr and 22Cr stainless steel and N80 and P110 carbon steel when exposed to 15 wt.% HCl solutions, at 50 deg C, 80 deg C and 100 deg C. The best corrosion inhibition efficiency is obtained when the concentration of both AC and HS is 1.5 wt. %, which indicates the use of all tested steels in oil well stimulation operated at 50 deg C and the use of 13Cr, N80 and P110 steels in oil well processing temperatures up to 100 deg C. (author)

  1. The electronic structure and second-order nonlinear optical properties of donor-acceptor acetylenes - A detailed investigation of structure-property relationships

    Science.gov (United States)

    Stiegman, A. E.; Graham, Eva; Khundkar, Lutfur R.; Perry, Joseph W.; Cheng, L.-T.; Perry, Kelly J.

    1991-01-01

    A series of donor-acceptor acetylene compounds was synthesized in which systematic changes in both the conjugation length and the donor-acceptor strength were made. The effect of these structural changes on the spectroscopic and electronic properties of the molecules and, ultimately, on the measured second-order molecular hyperpolarizabilities (beta) was investigated. It was found that increases in the donor-acceptor strength resulted in increases in the magnitude of beta. For this class of molecules, the increase is dominated by the energy of the intramolecular charge-transfer transition, while factors such as the ground to excited-state dipole moment change and the transition-moment integral are much less important. Increasing the conjugation length from one to two acetylene linkers did not result in an increase in the value of beta; however, beta increased sharply in going from two acetylenes to three. This increase is attributed to the superposition of several nearly isoenergetic excited states.

  2. HYDROESTERIFICATION OF ACETYLENE WITH METHYL FORMATE TO METHYL ACRYLATE OVER A NiO/Al203 CATALYST: EFFECTS OF NiO LOADING AND CALCINATION TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    Huang Xinhan; Yang Xiangui; Zhang Jiaqi; Liu Zhaotie

    2001-01-01

    Hydroesterification of acetylene with methyl formate (MF) was studied over a series of nickel-supported catalysts with NiO loading varing from 0.8 wt% to 18.7 wt% and calcination temperature ranging from 623 K to 873 K. The catalyst was studied by TPR, XPS, XRD and BET. The interactions between impregnated Ni2+ and alumina during catalyst preparation produced different kinds of nickel species such as NiO crystallites and NiAl2O4-like species, and their distributions varied with NiO loading and calcination temperature, which leads to different activities of catalyst in hydroesterification of acetylene with methyl formate. Experimental results indicated that 10wt% NiO/Al2O3 calcined at 773 K is suitable for the hydroesterification of acetylene with methyl formate.

  3. Cross-coupling of propargylated arabinogalactan with 2-bromothiophene.

    Science.gov (United States)

    Parshina, Lidiya N; Grishchenko, Lyudmila A; Larina, Lyudmila I; Novikova, Lyubov N; Trofimov, Boris A

    2016-10-01

    Novel pharmacologically prospective derivatives of arabinogalactan (a polysaccharide from larch wood) containing acetylenic and thiophene moieties have been obtained in up to 90% yield by cross-coupling of propargylic ethers of arabinogalactan with 2-bromothiophene. The reaction proceeds in the presence of the catalytic system Pd(Ph3P)4/CuBr/LiBr and piperidine in DMSO at 80-85°С. An advantageous feature of the synthesis is that it requires 5-25 times lesser catalytic loading than in common Sonogashira protocols thus making the reaction particularly beneficial to synthesize pharmaceutically-oriented polysaccharides. PMID:27312616

  4. Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane

    Science.gov (United States)

    Blass, William E.; Daunt, Stephen J.; Peters, Antoni V.; Weber, Mark C.

    1990-01-01

    Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned.

  5. Effects of acetylene flow rate and processing temperature on graphene films grown by thermal chemical vapor deposition

    International Nuclear Information System (INIS)

    We used thermal chemical vapor deposition (CVD) to synthesize few-layer graphene (FLG) films at a low temperature (600 °C). The FLG films were synthesized on Ni foils using a gaseous mixture of various ratios of H2 to acetylene (C2H2). We investigated that the effects of C2H2 flow on the structural properties of graphene. The quality of low-temperature CVD FLG films was investigated by Raman spectroscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. The results of Raman spectroscopy revealed that C2H2 flux clearly influences the features of FLG films. To enhance the quality of FLG films grown by low-temperature CVD, the films were grown under various gas flow ratios. The results demonstrated that the common thermal CVD method that uses C2H2 as a supplemental carbon source constitutes a low-cost and easy way to synthesize graphene films at low temperature for graphene-based applications. - Highlights: • We synthesized the graphene on nickel foil by thermal CVD method. • The graphene was successfully synthesized at a low temperature of 600 °C. • The acetylene flows were controlled to enhance the quality of graphene

  6. The Effect of Surface Finish on Low-Temperature Acetylene-Based Carburization of 316L Austenitic Stainless Steel

    Science.gov (United States)

    Ge, Yindong; Ernst, Frank; Kahn, Harold; Heuer, Arthur H.

    2014-12-01

    We observed a strong influence of surface finish on the efficacy of low-temperature acetylene-based carburization of AISI 316L austenitic stainless steel. Steel coupons were prepared with different surface finishes prior to carburization, from P400 SiC grit paper to 1- µm-diameter-diamond-paste. The samples with the finer surface finish developed a thicker "case" (a carbon-rich hardened surface layer) and a larger surface carbon concentration. Transmission electron microscopy revealed that the differences arose mainly from the nature of the deformation-induced disturbed layer on the steel surface. A thick (>400 nm) disturbed layer consisting of nano-crystalline grains (≈10 nm diameter) inhibits acetylene-based carburization. The experimental observations can be explained by assuming that during machining or coarse polishing, the surface oxide layer is broken up and becomes incorporated into the deformation-induced disturbed layer. The incorporated oxide-rich films retard or completely prevent the ingress of carbon into the stainless steel.

  7. The role of tin-promoted Pd/MWNTs via the management of carbonaceous species in selective hydrogenation of high concentration acetylene

    Science.gov (United States)

    Esmaeili, Elaheh; Mortazavi, Yadollah; Khodadadi, Abbas Ali; Rashidi, Ali Morad; Rashidzadeh, Mehdi

    2012-12-01

    In the present study, Pd/MWNTs are synthesized using polyol process and modified by tin as a promoter for selective hydrogenation of high concentrated acetylene feedstock. Polyol method results in highly dispersed nanoparticles with a depletion of particle size for tin-promoted Pd catalysts as characterized by TEM. Tin promoter plays a considerable role in hydrogenation of pure acetylene stream. This is attributed to formation of Pd2Sn structural phase, confirmed by XRD and TPR techniques, composed mainly of intermetallic species. Catalytic behavior of tin-promoted Pd catalysts is affected by geometric and electronic factors which are more pronounced in the case of Sn/Pd = 0.25. A discontinuity in Arrhenius plots for the Sn-promoted catalysts is appeared, which seems to be due to a kinetic factor as a result of change in acetylene coverage on Pd metallic ensembles at low and high temperature ranges. Higher selectivity of the catalysts to ethylene is attributed to the presence of more isolated adsorption sites on the catalyst surface originated from both intermetallic compounds confirmed by XPS and the ones formed via the carbonaceous species upon the acetylene hydrogenation reaction.

  8. Intramolecular competition between n-pair and π-pair hydrogen bonding: Microwave spectrum and internal dynamics of the pyridine–acetylene hydrogen-bonded complex

    Energy Technology Data Exchange (ETDEWEB)

    Mackenzie, Rebecca B.; Dewberry, Christopher T.; Leopold, Kenneth R., E-mail: A.C.Legon@bristol.ac.uk, E-mail: david.tew@bristol.ac.uk, E-mail: kleopold@umn.edu [Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, Minnesota 55455 (United States); Coulston, Emma; Cole, George C. [Department of Chemistry, University of Exeter, Stocker Road, Exeter EX4 4QD (United Kingdom); Legon, Anthony C., E-mail: A.C.Legon@bristol.ac.uk, E-mail: david.tew@bristol.ac.uk, E-mail: kleopold@umn.edu; Tew, David P., E-mail: A.C.Legon@bristol.ac.uk, E-mail: david.tew@bristol.ac.uk, E-mail: kleopold@umn.edu [Department of Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS (United Kingdom)

    2015-09-14

    a-type rotational spectra of the hydrogen-bonded complex formed from pyridine and acetylene are reported. Rotational and {sup 14}N hyperfine constants indicate that the complex is planar with an acetylenic hydrogen directed toward the nitrogen. However, unlike the complexes of pyridine with HCl and HBr, the acetylene moiety in HCCH—NC{sub 5}H{sub 5} does not lie along the symmetry axis of the nitrogen lone pair, but rather, forms an average angle of 46° with the C{sub 2} axis of the pyridine. The a-type spectra of HCCH—NC{sub 5}H{sub 5} and DCCD—NC{sub 5}H{sub 5} are doubled, suggesting the existence of a low lying pair of tunneling states. This doubling persists in the spectra of HCCD—NC{sub 5}H{sub 5}, DCCH—NC{sub 5}H{sub 5}, indicating that the underlying motion does not involve interchange of the two hydrogens of the acetylene. Single {sup 13}C substitution in either the ortho- or meta-position of the pyridine eliminates the doubling and gives rise to separate sets of spectra that are well predicted by a bent geometry with the {sup 13}C on either the same side (“inner”) or the opposite side (“outer”) as the acetylene. High level ab initio calculations are presented which indicate a binding energy of 1.2 kcal/mol and a potential energy barrier of 44 cm{sup −1} in the C{sub 2v} configuration. Taken together, these results reveal a complex with a bent hydrogen bond and large amplitude rocking of the acetylene moiety. It is likely that the bent equilibrium structure arises from a competition between a weak hydrogen bond to the nitrogen (an n-pair hydrogen bond) and a secondary interaction between the ortho-hydrogens of the pyridine and the π electron density of the acetylene.

  9. Wavelength modulation spectroscopy at 1530.32 nm for measurements of acetylene based on Fabry-Perot tunable filter

    Science.gov (United States)

    Yun-Long, Li; Bing-Chu, Yang; Xue-Mei, Xu

    2016-02-01

    Sensitive detection of acetylene (C2H2) is performed by absorption spectroscopy and wavelength modulation spectroscopy (WMS) based on Fiber Fabry-Perot tunable filter (FFP-TF) at 1530.32 nm. After being calibrated by Fiber Bragg Grating (FBG), FFP-TF is frequency-multiplexed and modulated at 20 Hz and 2.5 kHz respectively to achieve wavelength modulation. The linearity with 0.9907 fitting coefficient is obtained by measuring different concentrations in a 100 ppmv-400 ppmv range. Furthermore, the stability of the system is analyzed by detecting 50 ppmv and 100 ppmv standard gases for 2 h under room temperature and ambient pressure conditions respectively. The precision of 11 ppmv is achieved by calculating the standard deviation. Therefore, the measuring system of C2H2 detection can be applied in practical applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61172047 and 61071025).

  10. The Breathing Orbital Valence Bond Method in Diffusion Monte Carlo: C-H Bond Dissociation ofAcetylene

    Energy Technology Data Exchange (ETDEWEB)

    Domin, D.; Braida, Benoit; Lester Jr., William A.

    2008-05-30

    This study explores the use of breathing orbital valence bond (BOVB) trial wave functions for diffusion Monte Carlo (DMC). The approach is applied to the computation of the carbon-hydrogen (C-H) bond dissociation energy (BDE) of acetylene. DMC with BOVB trial wave functions yields a C-H BDE of 132.4 {+-} 0.9 kcal/mol, which is in excellent accord with the recommended experimental value of 132.8 {+-} 0.7 kcal/mol. These values are to be compared with DMC results obtained with single determinant trial wave functions, using Hartree-Fock orbitals (137.5 {+-} 0.5 kcal/mol) and local spin density (LDA) Kohn-Sham orbitals (135.6 {+-} 0.5 kcal/mol).

  11. Denitrification rate determined by nitrate disapperance is higher than determined by nitrous oxide production with acetylene blockage

    DEFF Research Database (Denmark)

    Yu, Kewei; Struwe, Sten; Kjøller, Annelise;

    2008-01-01

    A mixed beech and spruce forest soil was incubated under potential denitrification assay (PDA) condition with 10% acetylene (C2H2) in the headspace of soil slurry bottles. Nitrous oxide (N2O) concentration in the headspace, as well as nitrate, nitrite and ammonium concentrations in the soil...... different treatments. Commonly applied PDA measurement likely underestimates the nitrate removal capacity of a system. Incubation time and organic matter/nitrate ratio are the most critical factors to consider using C2H2 inhibition technique to quantify denitrification. By comparing the treatments with and...... slurries were monitored during the incubation. Results show that nitrate disappearance rate was higher than N2O production rate with C2H2 blockage during the incubation. Sum of nitrate, nitrite, and N2O with C2H2 blockage could not recover the original soil nitrate content, showing an N imbalance in such a...

  12. Mid-Infrared Pumped Laser-Induced Thermal Grating Spectroscopy for Detection of Acetylene in the Visible Spectral Range.

    Science.gov (United States)

    Sahlberg, Anna-Lena; Kiefer, Johannes; Aldén, Marcus; Li, Zhongshan

    2016-06-01

    We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 µm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm(-1), which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N2, air, CO2 and Ar with small admixtures of C2H2 A detection limit of less than 300 ppm was found for a point measurement of C2H2 diluted in N2 As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C2H2 and CO2 compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range. PMID:27091904

  13. Fabrication and Characterization of Nanocarbon-Based Nanofluids by Using an Oxygen-Acetylene Flame Synthesis System

    Science.gov (United States)

    Teng, Tun-Ping; Wang, Wei-Ping; Hsu, Yu-Chun

    2016-06-01

    In this study, an oxygen-acetylene flame synthesis system was developed to fabricate nanocarbon-based nanofluids (NCBNFs) through a one-step synthesis method. Measured in liters per minute (LPM), the flame's fuel flows combined oxygen and acetylene at four ratios: 1.5/2.5 (P1), 1.0/2.5 (P2), 0.5/2.5 (P3), and 0/2.5 (P4). The flow rate of cooling water (base fluid) was fixed at 1.2 LPM to produce different nanocarbon-based materials (NCBMs) and various concentrations of NCBNFs. Tests and analyses were conducted for determining the morphology of NCBMs, NCBM material, optical characteristics, the production rate, suspension performance, average particle size, zeta potential, and other relevant basic characteristics of NCBNFs to understand the characteristics and materials of NCBNFs produced through different process parameters (P1-P4). The results revealed that the NCBMs mainly had flaky and spherical morphologies and the diameters of the spherical NCBMs measured approximately 20-30 nm. X-ray diffraction and Raman spectroscopy revealed that the NCBMs contained graphene oxide (GO) and amorphous carbon (AC) when the oxygen flow rate was lower than 1.0 LPM. In addition, the NCBMs contained reduced GO, crystalline graphite (graphite-2H), and AC when the oxygen flow rate was higher than 1.0 LPM. The process parameters of P1, P2, P3, and P4 resulted in NCBMs produced at concentrations of 0.010, 0.013, 0.040, and 0.023 wt%, respectively, in NCBNFs. All the NCBNFs exhibited non-Newtonian and shear-thinning rheological properties. The P4 ratio showed the highest enhancement rate of thermal conductivity for NCBNFs, at a rate 4.85 % higher than that of water.

  14. Fabrication and Characterization of Nanocarbon-Based Nanofluids by Using an Oxygen-Acetylene Flame Synthesis System.

    Science.gov (United States)

    Teng, Tun-Ping; Wang, Wei-Ping; Hsu, Yu-Chun

    2016-12-01

    In this study, an oxygen-acetylene flame synthesis system was developed to fabricate nanocarbon-based nanofluids (NCBNFs) through a one-step synthesis method. Measured in liters per minute (LPM), the flame's fuel flows combined oxygen and acetylene at four ratios: 1.5/2.5 (P1), 1.0/2.5 (P2), 0.5/2.5 (P3), and 0/2.5 (P4). The flow rate of cooling water (base fluid) was fixed at 1.2 LPM to produce different nanocarbon-based materials (NCBMs) and various concentrations of NCBNFs. Tests and analyses were conducted for determining the morphology of NCBMs, NCBM material, optical characteristics, the production rate, suspension performance, average particle size, zeta potential, and other relevant basic characteristics of NCBNFs to understand the characteristics and materials of NCBNFs produced through different process parameters (P1-P4). The results revealed that the NCBMs mainly had flaky and spherical morphologies and the diameters of the spherical NCBMs measured approximately 20-30 nm. X-ray diffraction and Raman spectroscopy revealed that the NCBMs contained graphene oxide (GO) and amorphous carbon (AC) when the oxygen flow rate was lower than 1.0 LPM. In addition, the NCBMs contained reduced GO, crystalline graphite (graphite-2H), and AC when the oxygen flow rate was higher than 1.0 LPM. The process parameters of P1, P2, P3, and P4 resulted in NCBMs produced at concentrations of 0.010, 0.013, 0.040, and 0.023 wt%, respectively, in NCBNFs. All the NCBNFs exhibited non-Newtonian and shear-thinning rheological properties. The P4 ratio showed the highest enhancement rate of thermal conductivity for NCBNFs, at a rate 4.85 % higher than that of water. PMID:27295256

  15. Impact Analysis of GNSS Signal Imperfections on Intersystem and Intrasystem Interference%发射信号不完善性对卫星导航系统内及系统间干扰的影响分析

    Institute of Scientific and Technical Information of China (English)

    张铮文; 寇艳红; 刘建胜

    2011-01-01

    Three types of satellite signal imperfection-incompletely suppressed carrier, intermodulation distortion and spurious emissions-and their interference on GNSS signal receiving are studied in this paper.The interference effects are quantitatively analyzed based on signal modeling and analytical computation of the spectral separation coefficient (SSC),the code tracking SSC (CT-SSC) and the effective carrier to noise ratio.Using the signals in GPS L1 and Galileo E1 band, the effects of the noise, the signal processing loss, the external interference, GNSS intrasystem interference and intersystem interference in the presence of different combination of the three types of signal imperfection are calculated.The results show that when the total signal imperfection interference reaches a certain power level, it will have more impacts on signal acquisition, carrier tracking and dada demodulation than intersystem interference.This analysis provides a reference for the specification of the satellite signal quality.%研究了3种典型的卫星发射信号不完善性--载波泄漏、互调失真和杂散辐射对于卫星导航信号的接收所带来的干扰,通过信号建模以及谱分离系数、码跟踪谱灵敏度系数和等效载噪比的解析计算对干扰效果进行量化分析;针对GPS和Galileo系统L1/E1频段的信号进行了多层次的仿真计算,给出了综合考虑噪声、信号损耗、外源干扰,GNSS系统内和系统间干扰,以及3种信号不完善性单独作用、两两组合和综合作用下的结果,其中对于GPS L1 C/A短码考虑了电文调制对线谱的影响.结果表明,当总的不完善干扰功率水平达到一定程度后,其对接收机信号捕获跟踪和解调的影响大于系统间干扰,不能忽略.

  16. A Novel Multi-Point Fiber Optics Acetylene Sensing System Based on Dense Wavelength Division Multiplexers%基于波分复用的多点光纤乙炔传感系统

    Institute of Scientific and Technical Information of China (English)

    余贶琭; 吴重庆; 郭旋; 王智; 石梅荣; 武文彬

    2011-01-01

    The Beer-Lambert law, taking into account the pressure broadening of the absorption lines function is analyzed, then it is used for multi-point acetylene gas detection. A fiber optical multi-point acetylene sensing system using dense wavelength division multiplexers, which takes advantage of different absorption lines to tag different probes in the system, is put forward. This system is easy to build and operate, while it does not need to modulate the light source. In addition, the system has a much smaller system loss and cross talks as the consequences of employing the dense wavelength division multiplexers. Theoretical results show that the maximum sensor number of the system is eighteen with a 0.5 % sensitivity using the absorption lines from 1510 to 1540 nm. A three-point sensing system is experimentally demonstrated and the errors of the measured results are within 1.8 %.%理论分析了考虑吸收线型函数展宽时的Beer-Lambert定律,作了进一步推导并应用于多点乙炔气体监测.提出一种采用波分复用器、利用吸收峰区分不同传感点的多点光纤乙炔传感系统,系统简单易操作,无需对光源进行调制,且系统损耗与串扰小.理论分析表明当目标检测灵敏度为0.5%时,在1510~1540 nm范围内该系统最大可监测18个传感点.搭建了一个3个监测点的乙炔传感系统并验证了上述理论的可行性,各传感点的测量误差均小于1.8%.

  17. Recent Line-Shape and Doppler Thermometry Studies Involving Transitions in the ν1 +ν3 Band of Acetylene

    Science.gov (United States)

    Hashemi, Robab; Rozario, Hoimonti; Povey, Chad; Garber, Jolene; Derksen, Mark; Predoi-Cross, Adriana

    2014-06-01

    The line positions for transitions in the ν1 +ν3 band are often used as a frequency standard by the telecom industry and also needed for planetary atmospheric studies. Four relevant studies have been recently carried out in our group and will be discussed briefly below. (1) N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the ν1 +ν3 band of acetylene at seven temperatures in the range 213333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. This study has been published in Molecular Physics, 110 Issue 21/22 (2012) 2645-2663. (2) Six nitrogen perturbed transitions of acetylene within the ν1 +ν3 absorption band have been recorded using a 3-channel diode laser spectrometer. We have examined C2H2 spectra using a hard collision (Rautian) profile over a range of five temperatures (213 K-333 K). From these fits we have obtained the N2-broadening and narrowing coefficients of C2H2 and examined their temperature dependence. The experimentally measured narrowing coefficients have been used to estimate the nitrogen diffusion coefficients. The broadening coefficients and corresponding temperature dependence exponents have also been compared to that of calculations completed using a classical impact approach on an ab initio potential energy surface. We have observed a good agreement between our theoretical and experimental results. This study was published in Canadian Journal of Physics 91(11) 896-905 (2013). (3) An extension of the previous study was to analyze the room temperature for the same six transitions using the Voigt, Rautian, Galatry, RautianGalatry and Correlated Rautian profiles. For the entire pressure range, we have tested the applicability of these line-shape models. Except for Voigt profile, Dicke narrowing effect has been considered in all mentioned line-shape models. The experimental

  18. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination.

    Science.gov (United States)

    Dai, Bin; Wang, Qinqin; Yu, Feng; Zhu, Mingyuan

    2015-01-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au(3+) reduction to metallic Au(0) is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction time. The results indicated that metallic Au(0) exhibits considerable catalytic activity and that Au nano-particle aggregation may be another reason for the AuCl3/AC catalytic activity in acetylene hydrochlorination. PMID:25994222

  19. Measurements of linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene in the ν4+ν5 combination band using a cw quantum cascade laser

    KAUST Repository

    Sajid, Muhammad Bilal

    2014-11-01

    Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296K in the P branch of the ν4+ν5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296-683K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253-1310cm-1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ν4+ν5 combination band and other vibrational bands of acetylene. © 2014 Elsevier Ltd.

  20. Xe-bearing hydrocarbon ions: Observation of Xe.acetylene+rad and Xe.benzene+rad radical cations and calculations of their ground state structures

    Science.gov (United States)

    Cui, Zhong-hua; Attah, Isaac K.; Platt, Sean P.; Aziz, Saadullah G.; Kertesz, Miklos; El-Shall, M. S.

    2016-04-01

    This work reports evidence for novel types of Xe-bearing hydrocarbon radical cations. The Xe.acetylene+rad radical cation adduct is observed at nearly room temperature using the mass-selected drift cell technique. The irreversible addition of the Xe atom and the lack of back dissociation to HCCH+rad + Xe is consistent with the calculated binding energy of 0.85 eV to be contrasted with the metastable nature of the neutral Xe.acetylene adduct. The observed Xe.benzene+rad radical cation appears to be a weakly bound complex stabilized mainly by ion-induced dipole interaction consistent with a calculated binding energy in the range of 0.14-0.17 eV.

  1. Observation of Coriolis Coupling between nu(2) + 4nu(4) and 7nu(4) in Acetylene &Xtilde;(1)Sigma(+)(g) by Stimulated Emission Pumping Spectroscopy.

    Science.gov (United States)

    Moss; Duan; Jacobson; O'Brien; Field

    2000-02-01

    Stimulated emission pumping (SEP) spectroscopy has been used to examine a low energy region (E(vib) approximately 4400 cm(-1)) of &Xtilde;(1)Sigma(+)(g) acetylene at higher resolution than was possible in previous dispersed fluorescence studies. The expected bright state, nu(2) + 4nu(4), is observed to be coupled to the nearly degenerate 7nu(4) state by a Coriolis mechanism. A least-squares analysis yields values for zero-order vibrational energies, rotational constants, and a Coriolis-coupling coefficient that are all consistent with expectations. Calculated relative intensities of SEP transitions, accounting for interference due to axis-switching effects, are also consistent with observations. Implications of the observed Coriolis resonance with regard to global acetylene vibrational dynamics are also discussed. Copyright 2000 Academic Press.

  2. Dynamic study of carbon nanotube growth and catalyst morphology evolution during acetylene decomposition on Co/SBA-15 in an environmental TEM

    DEFF Research Database (Denmark)

    s Aires, F. J. Cadete Santo; Epicier, T.; Wagner, Jakob Birkedal;

    2012-01-01

    In situ studies of micro- and nano-objects in their characteristic environment have been performed ever since the early days of electron microscopy [1]. Over several decades the in situ observation of the synthesis of filamentous carbon (nanotubes/nanofilaments) during hydrocarbon decomposition has...... been one of the most popular topics [2] for investigation in the environmental transmission electron microscope (ETEM). In this work we study the growth of carbon nanotubes (CNTs) by the decomposition of acetylene on Co nanoparticles inserted into mesoporous silicas (SBA-15) using both conventional...... post mortem TEM measurements and real-time in situ ETEM observations. In situ observation of the formation of the carbon nanotubes was performed in an FEI Titan 80-300 ETEM equipped with an objective lens spherical aberration corrector [3]. Prior to acetylene decomposition, the catalyst nanoparticles...

  3. Effects of acido-basic support properties on the catalytic hydrogenation of acetylene on gold nano-particles

    Science.gov (United States)

    Manda, Abdullah Ahmed

    Metallic gold nanoparticles supported on gamma-Al2O 3 and magnesia-alumina mixed oxide, with different magnesia content have been prepared by sol-gel method and characterized by different techniques (inductive coupled plasma-mass spectroscopy (ICP-MS), XRD, BET surface area analysis, transmission electron microscopy (TEM), CO2 and NH 3 temperature programmed desorption (TPD), H2 temperature programmed reduction (TPR) and FTIR of adsorbed CO2). Such systems were found to produce catalysts with controllable acidity, varying from catalyst possessing large density of acidic and low density of basic sites, others with acidic and basic sites of equal strength and density, and others with large basic and low acid sites densities, respectively. The catalytic assessment of the generated acidity was carried out using 2-propanol decomposition as a test reaction. The results obtained indicate that the presence of magnesia and reduced gold nanopartilces has imparted the catalysts, 1%Au/4%Mg-Al 2O3 and 1%Au/8%Mg-Al2O3, with significant base-catalytic properties. Acetylene hydrogenation and formation of coke deposits were investigated on a gold catalyst supported on gamma-Al2O3 and gold supported on alumina-magnisia mixed oxide with different gold content; 1%Au/gamma-Al 2O3, 1%Au/15%Mg-Al2O3, 2%Au/15%Mg-Al 2O3 and 4%Au/15%Mg-Al2O3. The effect of the H2/C2H2 ratio was studied over a range of values. The catalytic activity and selectivity towards ethylene and other products were investigated at different reaction temperatures. Acetylene hydrogenation was investigated in the presence and absence of ethylene in stream. It is investigated that the adsorption of the triple bond is preferred over the double bond and during selective catalytic (SCR) of C2H2 the two hydrocarbons do not compete for the same adsorption sites. The deactivation of catalysts was studied by temperature programmed oxidation (TPO). Higher content of coke over 1%Au/Al2O3 catalyst was investigated in contrast to

  4. Effects of acetylene at low concentrations on nitrification, mineralization and microbial biomass nitrogen concentrations in forest soils

    Institute of Scientific and Technical Information of China (English)

    ZHANG TengYu; XU XingKai; LUO XianBao; HAN Lin; WANG YingHong; PAN GenXing

    2009-01-01

    Temperate forest surface soils at the varying distances from main trunks (e.g., Pinus koraiensis and Quercus mongolica) were used to study the effects of acetylene (C2H2) at low concentrations on nitri-fication, mineralization and microbial biomass N concentrations of the soils, and to assess the contri-bution of heterotrophic nitrification to nitrous oxide (N2O) emissions from soils. The use of acetylene at partial pressures within a range from 10 to 100 Pa C2H2 in headspace gas gave a significant decrease in N2O emission at soil moisture of c. 45% water-filled porosity space, and the decrease was almost the same in each soil after exposure of C2H2 at low concentrations. Heterotrophic nitrification could ac-count for 21%-48% of total N2O emission from each soil; the contribution would increase with in-creasing distances from the Pinus koraiensis trunks rather than from the Quercus mongolica trunks.Under the experimental conditions, the use of C2H2 at low concentrations showed no significant influ-ence on soil microbial biomass N, net N mineralization and microbial respiration. However, 100 Pa C2H2in headspace gas could reduce carbon dioxide (CO2) emissions from soils. According to the rapid consumption of 10 Pa C2H2 by forest soils and convenience for laboratory incubations, 50 Pa C2H2 in headspace gas can be used to study the origin of N2O emissions from forest soils under aerobic con-ditions and the key associated driving mechanisms. The N2O and CO2 emissions from the soils at the same distances from the Quercus mongolica trunks were larger than those from the Pinus koraiensis trunks, and both emissions decreased as the distances from trunks increased. The stepwise regression analysis showed that 95% of the variability in soil CO2 emissions could be accounted for by the con-centrations of soil total C and water soluble organic C and soil pH, and that 72% of the variability in soil N2O emissions could be accounted for by the concentrations of soil total N

  5. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination

    OpenAIRE

    Bin Dai; Qinqin Wang; Feng Yu; Mingyuan Zhu

    2015-01-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au3+ reduction to metallic Au0 is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction...

  6. Synthesis of phenyl(1-/sup 14/C)acetylene and 1,4-diphenyl (1,4-/sup 14/C/sub 2/)butadiyne

    Energy Technology Data Exchange (ETDEWEB)

    Dhawan, S.N.; Kagan, J. (Illinois Univ., Chicago (USA). Dept. of Chemistry)

    1982-03-01

    Phenyl(1-/sup 14/C)acetylene (0.012mCi/mmole) was synthesized in 12.5% yield from (1-/sup 14/C)acetic acid through (1-/sup 14/C)acetophenone, its semicarbazone, and 4-phenyl-(4-/sup 14/C)1,2,3-selenadiazole obtained by selenium dioxide oxidation. Oxidative coupling gave 1,4-diphenyl(1,4-/sup 14/C/sub 2/)butadiyne in 80% yield.

  7. Three-step laser induced ionization of Ir and Hg atoms in an air-acetylene flame and a gas cell

    International Nuclear Information System (INIS)

    The feasibility and the application of three-step excitation and ionization schemes with excimer-pumped, pulsed dye lasers have been studied in the case of Iridium atoms in an air acetylene flame and of Mercury atoms in a gas cell. The detection limits obtained were 0.2 ng/ml in the case of Ir and 107 atoms per cubic centimeter of air

  8. Acetylene inhibition of N2O reduction in laboratory soil and groundwater denitrification assays: evaluation by 15N tracer and 15N site preference of N2O

    OpenAIRE

    Weymann, Daniel; Well, Reinhard; Lewicka-Szczebak, Dominika; Rohe, Lena

    2013-01-01

    Acetylene inhibition of N2O reduction in laboratory soil and groundwaterdenitrification assays: evaluation by 15N tracer and 15N site preference ofN2ODaniel Weymann (1), Reinhard Well (2), Dominika Lewicka-Szczebak (2,3), and Rohe Lena (2)(1) Forschungszentrum Juelich, Agrosphere Institute (IBG-3), Juelich, Germany (), (2)Thünen-Institute of Climate-Smart Agriculture, Braunschweig, Germany, (3) University of Wroclaw, PolandThe measurement of denitrification in soils and...

  9. Shock tube/laser absorption measurements of methane, acetylene and ethylene during the pyrolysis of n-pentane and iso-pentane

    KAUST Repository

    Sajid, Muhammad Bilal

    2015-11-09

    Pentane isomers are important constituents of distillate gasoline, compressed natural gas and liquefied petroleum gas. Pentane chemistry is integral component of the chemical kinetic mechanisms of larger hydrocarbons. Existing kinetic mechanisms differ in their predictions of the oxidative and pyrolysis behavior of pentane isomers. This work provides new species time-history data to validate and improve pentane chemistry models. Methane, acetylene and ethylene are measured during the high-temperature pyrolysis of n-pentane and iso-pentane. Experiments are performed behind reflected shock waves over 1400–2100 K and pressures near 1 atm. Methane and acetylene are measured using a quantum cascade laser operating near 8 µm, whereas ethylene is measured with a CO2 gas laser operating near 10.6 µm. A two-color technique is used to eliminate broadband interference caused by large hydrocarbons. Measurements are compared with predictions of existing chemical kinetic mechanisms which underpredict the formation of methane and acetylene but overpredict ethylene formation.

  10. Exergy Analysis and Retrofitting of Natural Gas-based Acetylene Process%天然气基乙炔工艺(火用)分析与改进

    Institute of Scientific and Technical Information of China (English)

    王志方; 郑丹星

    2008-01-01

    This article presents an acetylene production process by partial oxidation/combustion of natural gas.The thermodynamic performance and exergy analysis in the process are investigated using the tlow-sheetmg pro-gram Aspen Plus.The results indicate that the most important destruction of exergy is found to occur in the reactor and water quenching scrubber,amounting to 8.23%and 10.39%.respectively,of the entire system.Based on the results of thermodynamic and exergy analysis,the acetylene reactor has been retrofitted.The improvement ratios of molar O2 to CH4 and molar CO to CH4 are 0.65 and 0.20,respectively.An improvement of the acetylene production system is proposed.Adopting the improvement operation conditions and using oil to realize the reaction heat re- covery,the feedstock of natural gas is reduced by 9.88%and the exergy loss in the retrofitting process is decreased by 19.71%comparedtotheoriginalprocess.

  11. Azidopropylvinylsulfonamide as a New Bifunctional Click Reagent for Bioorthogonal Conjugations: Application for DNA-Protein Cross-Linking.

    Science.gov (United States)

    Dadová, Jitka; Vrábel, Milan; Adámik, Matej; Brázdová, Marie; Pohl, Radek; Fojta, Miroslav; Hocek, Michal

    2015-11-01

    N-(3-Azidopropyl)vinylsulfonamide was developed as a new bifunctional bioconjugation reagent suitable for the cross-linking of biomolecules through copper(I)-catalyzed azide-alkyne cycloaddition and thiol Michael addition reactions under biorthogonal conditions. The reagent is easily clicked to an acetylene-containing DNA or protein and then reacts with cysteine-containing peptides or proteins to form covalent cross-links. Several examples of bioconjugations of ethynyl- or octadiynyl-modified DNA with peptides, p53 protein, or alkyne-modified human carbonic anhydrase with peptides are given.

  12. Optimization of Acetylene Black Conductive Additive andPolyvinylidene Difluoride Composition for High Power RechargeableLithium-Ion Cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, G.; Zheng, H.; Battaglia, V.S.; Simens, A.S.; Minor, A.M.; Song, X.

    2007-07-01

    Fundamental electrochemical methods were applied to study the effect of the acetylene black (AB) and the polyvinylidene difluoride (PVDF) polymer binder on the performance of high-power designed rechargeable lithium ion cells. A systematic study of the AB/PVDF long-range electronic conductivity at different weight ratios is performed using four-probe direct current tests and the results reported. There is a wide range of AB/PVDF ratios that satisfy the long-range electronic conductivity requirement of the lithium-ion cathode electrode; however, a significant cell power performance improvement is observed at small AB/PVDF composition ratios that are far from the long-range conductivity optimum of 1 to 1.25. Electrochemical impedance spectroscopy (EIS) tests indicate that the interfacial impedance decreases significantly with increase in binder content. The hybrid power pulse characterization results agree with the EIS tests and also show improvement for cells with a high PVDF content. The AB to PVDF composition plays a significant role in the interfacial resistance. We believe the higher binder contents lead to a more cohesive conductive carbon particle network that results in better overall all local electronic conductivity on the active material surface and hence reduced charge transfer impedance.

  13. Acetylene - Argon Plasmas Measured at a Biased Substrate Electrode for Diamond-Like Carbon Deposition. Part 2: Ion Energy Distributions

    CERN Document Server

    Baby, A; Lemoine, P; Maguire, P D

    2008-01-01

    Ion energy distributions have been determined at the rf-bias electrode in an inductively-coupled acetylene-argon plasma for various substrate bias voltages and frequencies under conditions suitable for film deposition. These are compared with those obtained at the grounded wall of a capacitively coupled plasma. In the former, for pressures up to 25 mTorr, the IEDs exhibit bimodal structures with peak separation values that follow the expected dependence on voltage and frequency. At higher pressures, 120 mTorr, the bimodal structure is replaced by a single peak. For all conditions, the dominant ion is Ar+ or ArH+ despite a set C2H2:Ar flow ratio of 2:1, and this can be attributed to the high electron dissociation of the parent molecule. Diamond-like carbon films indicate a peak hardness at an ion energy of around 90 eV and a very sharp fall in hardness is noted beyond this value. This is similar to the observed bombardment energy relationship for sp3 bond formation in hydrogen-free tetragonal amorphous carbon ...

  14. Direct Observation of Cascade of Photoinduced Ultrafast Intramolecular Charge Transfer Dynamics in Diphenyl Acetylene Derivatives: Via Solvation and Intramolecular Relaxation.

    Science.gov (United States)

    Karunakaran, Venugopal; Das, Suresh

    2016-07-21

    Interaction of light with electron donor-acceptor π-conjugated systems leading to intramolecular charge transfer (ICT) plays an essential role in transformation of light energy. Here the cascade of photoinduced ICT processes is directly observed by investigating the excited state relaxation dynamics of cyano and mono/di methoxy substituted diphenyl acetylene derivatives using femtosecond pump-probe spectroscopy and nanosecond laser flash photolysis. The femtosecond transient absorption spectra of the chromophores upon ultrafast excitation reveal the dynamics of intermediates involved in transition from initially populated Frank-Condon state to local excited state (LE). It also provides the dynamic details of the transition from the LE to the charge transfer state yielding the formation of the radical ions. Finally, the charge transfer state decays to the triplet state by geminate charge recombination. The latter dynamics are observed in the nanosecond transient absorption spectra. It is found that excited state relaxation pathways are controlled by different stages of solvation and intramolecular relaxation depending on the solvent polarity. The twisted ICT state is more stabilized (978 ps) in acetonitrile than cyclohexane where major components of transient absorption originate from the S1 state. PMID:27347705

  15. Superior mercury-free catalysts for acetylene hydrochlorination to VCM. Achieving high productivities and long catalyst life-time

    Energy Technology Data Exchange (ETDEWEB)

    Liebens, A.T.; Piccinini, M. [Solvay S.A., Bruxelles (Belgium)

    2013-11-01

    New mercury-free catalytic systems based on the use of ionic liquids (IL) and noble metals (e.g. Pd, Au) have been evaluated for the hydrochlorination reaction of acetylene to produce Vinyl Chloride Monomer (VCM). Two different approaches have been investigated: gas-liquid homogeneous catalytic systems in the presence of molten IL/Metal and heterogeneous gas-solid ones using solid materials. For the latter case, very positive results have been obtained using SILP-type catalysts (SILP: Supported Ionic Liquid Phase) where IL/Metal were deposited onto a solid mesoporous support. Remarkably, both systems display very high Space Time Yield (STY) and breakthrough life-time stability. No deactivation is observed even after 500 h on stream indicating the strong advantages of these new materials compared to most investigated Au/C supported systems. The development of heterogeneous catalysts was preferred as the scale-up of gas-liquid technology implies important CAPEX investments to convert current plants from gas-solid to gas-liquid equipment. (orig.)

  16. Synthesis of Highly Stable Silver-Loaded Vertical ZnO Nanowires Array and its Acetylene Sensing Properties

    Science.gov (United States)

    Uddin, Abu Sadat Mohammad Iftekhar; Chung, Gwiy-Sang

    2016-09-01

    A silver-loaded one-dimensional (1D) vertical ZnO nanowires (NWs) array synthesized by a facile seed mediated hydrothermal-RF magnetron sputtering method has been investigated for the fabrication of a highly stable and reproducible acetylene (C2H2) gas sensor. Successful immobilization of silver nanoparticles (NPs) as a sensitizer on the ZnO NWs array significantly enhanced the C2H2 sensing properties and showed a stable sensing performance. The grown structure exhibited high response magnitude (30.8 at 1000ppm), short response time (43s) and excellent selectivity at 220∘C. The enhanced performance can probably be accounted for the effect of combining the highly orientated ZnO NWs and catalytically active silver-based network. The superior sensing features toward C2H2 along with broad detection range (1-1000ppm), outstanding stability and excellent reproducibility indicate that the sensor is a promising candidate for practical applications.

  17. Rotationally Resolved Vacuum Ultraviolet Resonance-Enhanced Multiphoton Ionization (VUV REMPI) of Acetylene via the G̃ Rydberg State.

    Science.gov (United States)

    Schmidt-May, Alice F; Grütter, Monika; Neugebohren, Jannis; Kitsopoulos, T N; Wodtke, Alec M; Harding, Dan J

    2016-07-14

    We present a 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme for acetylene via the linear G̃ 4sσ (1)Πu Rydberg state, offering partial rotational resolution and the possibility to detect excitation in both the cis- and trans-bending modes. The resonant transition to the G̃ state is driven by a vacuum ultraviolet (VUV) photon, generated by resonant four-wave mixing (FWM) in krypton. Ionization from the short-lived G̃ state then occurs quickly, driven by the high intensity of the residual light from the FWM process. We have observed nine bands in the region between 79 200 cm(-1) and 80 500 cm(-1) in C2H2 and C2D2. We compare our results with published spectra in this region and suggest alternative assignments for some of the Renner-Teller split bands. Similar REMPI schemes should be applicable to other small molecules with picosecond lifetime Rydberg states. PMID:27073931

  18. The acetylene inhibition technique to determine total denitrification (N2 + N2O losses from soil samples: potentials and limitations

    Directory of Open Access Journals (Sweden)

    A. Neftel

    2012-03-01

    Full Text Available The loss of N2 from intensively managed agro-ecosystems is an important part of the N budget. The monitoring of N2 emissions at the field scale is impossible due to the high atmospheric background of 78%, which precludes the measurement of fluxes. The acetylene (C2H2 inhibition technique is a rather simple, albeit imperfect, method to determine N2 losses from entire soil cores. Despites serious limitations it is one among very few methodological options to estimate total denitrification at high temporal resolution and on small spatial scale, with limited workload and costs involved. A laboratory system with two different detection systems (photoacoustic IR spectroscopy and gas chromatography is presented, which allowed parallel measurements of up to 7 intact soil cores in air-tight glass tubes in a temperature controlled cabinet (adjusted to field conditions with an automated C2H2 injection. A survey of total denitrification losses (N2 + N2O over 1.5 yr in soil from an intensively managed, cut grassland system in central Switzerland showed a lower bound loss in the range of 6 to 25 kg N ha−1 yr−1 (3–13% of added N, roughly 3.4 times higher than the N2O loss. However, several drawbacks of the C2H2 inhibition technique preclude a more precise determination of the total denitrification loss.

  19. Measurements of hydrogen cyanide (HCN and acetylene (C2H2 from the Infrared Atmospheric Sounding Interferometer (IASI

    Directory of Open Access Journals (Sweden)

    V. Duflot

    2013-04-01

    Full Text Available Hydrogen cyanide (HCN and acetylene (C2H2 are ubiquitous atmospheric trace gases with medium lifetime, which are frequently used as indicators of combustion sources and as tracers for atmospheric transport and chemistry. Because of their weak infrared absorption, overlapped by the CO2 Q branch near 720 cm−1, nadir sounders have up to now failed to measure these gases routinely. Taking into account CO2 line mixing, we provide for the first time extensive measurements of HCN and C2H2 total columns at Reunion Island (21° S, 55° E and Jungfraujoch (46° N, 8° E in 2009–2010 using observations from the Infrared Atmospheric Sounding Interferometer (IASI. A first order comparison with local ground-based Fourier transform infraRed (FTIR measurements has been carried out allowing tests of seasonal consistency which is reasonably captured, except for HCN at Jungfraujoch. The IASI data shows a greater tendency to high C2H2 values. We also examine a nonspecific biomass burning plume over austral Africa and show that the emission ratios with respect to CO agree with previously reported values.

  20. Measurements of hydrogen cyanide (HCN and acetylene (C2H2 from the Infrared Atmospheric Sounding Interferometer (IASI

    Directory of Open Access Journals (Sweden)

    C. Clerbaux

    2012-10-01

    Full Text Available Hydrogen cyanide (HCN and acetylene (C2H2 are ubiquitous atmospheric trace gases with medium lifetime, which are frequently used as indicators of combustion sources and as tracers for atmospheric transport and chemistry. Because of their weak infrared absorption, overlapped by the CO2 Q-branch near 720 cm−1, nadir sounders have up to now failed to measure these gases routinely. Taking into account CO2 line mixing we provide for the first time extensive measurements of HCN and C2H2 total columns at Reunion Island (21° S; 55° E and Jungfraujoch (46° N; 8° E in 2009–2010 using observations from the Infrared Atmospheric Sounding Interferometer (IASI. These are compared with local ground-based Fourier Transform InfraRed (FTIR measurements and we demonstrate that the seasonality is well captured, except for HCN at Jungfraujoch. We also examine a nonspecific biomass burning plume over austral Africa and show that the emission ratios with respect to CO agree with previously reported values.

  1. NIR bacteriochlorin chromophores accessed by Heck and Sonogashira cross-coupling reactions on a tetrabromobacteriochlorin derivative.

    Science.gov (United States)

    de Assis, Francisco F; Ferreira, Marco A B; Brocksom, Timothy J; de Oliveira, Kleber T

    2016-01-28

    The synthesis of a new tetrabromobacteriochlorin BCBr4 is reported having the 3,4-dibromo-1H-pyrrole-2-carbaldehyde (10) as the major precursor. The BCBr4 was successfully employed in Pd cross-coupling reactions with methyl acrylate, phenyl acetylene and 4-ethynylanisole. In all three cases, the desired tetra-coupled products were obtained in good to excellent yields, and present a significant red shift in the UV-Vis bands above 800 nm. DFT and TD-DFT theoretical analyses of the NIR bacteriochlorin chromophores were performed in order to evaluate the effect of β substitution on their electronic structures. PMID:26676846

  2. Synthesis, characterization, and stability of Fe-MCM-41 for production of carbon nanotubes by acetylene pyrolysis.

    Science.gov (United States)

    Amama, Placidus B; Lim, Sangyun; Ciuparu, Dragos; Yang, Yanhui; Pfefferle, Lisa; Haller, Gary L

    2005-02-24

    Fe-substituted MCM-41 molecular sieves with ca. 1, 2, and 3 wt % Fe were synthesized hydrothermally using different sources of colloidal silica (HiSil and Cab-O-Sil) and characterized by ICP, XRD, N2 physisorption, UV-vis, EPR, TPR, and X-ray absorption. Catalysts synthesized from Cab-O-Sil showed higher structural order and stability than those from HiSil. The local environment of Fe in the mesoporous material as studied by UV-vis reveals the dominance of framework Fe in all the as-synthesized Fe-MCM-41 samples. Dislodgement of some Fe species to extraframework location occurs upon calcination, and this effect is more severe for Fe-MCM-41 (2 wt %) and Fe-MCM-41 (3 wt %), as confirmed by EPR and X-ray absorption. These materials have been used as catalytic templates for the production of carbon nanotubes (CNTs) by acetylene pyrolysis at atmospheric pressure. A relationship between the Fe loading in MCM-41 and the carbon species produced during this reaction has been established. Using our optimized conditions for this system, Fe-MCM-41 with ca. 2 wt % Fe showed the best results with particularly high selectivity for single-wall carbon nanotube (SWNT) production. This catalyst was selective for carbon nanotubes with a low amount of amorphous carbon for a narrow range of temperatures from 1073 to 1123 K. To account for the different selectivity of these catalysts for CNTs production, the local environment and chemical state of Fe in the used catalyst was further probed by X-band EPR. PMID:16851270

  3. Characterization of nitrogen-fixing bacteria from a temperate saltmarsh lagoon, including isolates that produce ethane from acetylene.

    Science.gov (United States)

    Tibbles, B J; Rawlings, D E

    1994-01-01

    Nitrogen-fixing bacteria were isolated from sediments and water of a saltmarsh lagoon on the west coast of South Africa, and characterized according to factors that regulate nitrogen fixation in the marine environment. The majority of isolates were assigned to the Photobacterium or Vibrio genera on the basis of physiological and biochemical characteristics. One isolate was further assigned to the species Vibrio diazotrophicus. Carbohydrate utilization by each diazotrophic isolate was examined. Abilities of the isolates to utilize a range of mono-, di-, and polysaccharides largely reflected the predicted availability of organic carbon and energy in the lagoon, except that chitin was not utilized. Biochemical tests on the utilization of combined nitrogen showed that one isolate could utilize nitrate, and that this strain was susceptible to full repression of nitrogenase activity by 10mM nitrate. Urease activity was not detected in any of the isolates. In the absence of molybdenum two of the isolates, a Photobacterium spp. and V. diazotrophicus, reduced acetylene to ethylene and ethane, a property frequently associated with the activity of alternative nitrogenases. Addition of 25µM molybdenum inhibited ethane production by V. diazotrophicus, but stimulated ethylene and ethane production by the Photobacterium isolate. Addition of 28µM vanadium did not appear to regulate ethane production by either strain. Assays of nitrogenase activity in sediments from which some isolates were obtained indicated that molybdenum was not limiting nitrogenase activity at naturally-occurring concentrations. Southern hybridizations of the chromosomes of these strains with the anfH and vnfH genes of Azotobacter vinelandii and the nifH gene of Klebsiella pneumoniae indicated the presence of only one nitrogenase in these isolates.

  4. A DFT study on the mechanisms for the cycloaddition reactions between 1-aza-2-azoniaallene cations and acetylenes.

    Science.gov (United States)

    Wang, Jing-mei; Li, Zhi-ming; Wang, Quan-rui; Tao, Feng-gang

    2013-01-01

    The mechanisms of cycloaddition reactions between 1-aza-2-azoniaallene cations 1 and acetylenes 2 have been investigated using the global electrophilicity and nucleophilicity of the corresponding reactants as global reactivity indexes defined within the conceptual density functional theory. The reactivity and regioselectivity of these reactions were predicted by analysis of the energies, geometries, and electronic nature of the transition state structures. The theoretical results revealed that the reaction features a tandem process: an ionic 1,3-dipolar cycloaddition to produce the cycloadducts 3 H-pyrazolium salts 3 followed by a [1,2]-shift affording the thermodynamically more stable adducts 4 or 5. The mechanism of the cycloaddition reactions can be described as an asynchronous concerted pathway with reverse electron demand. The model reaction has also been investigated at the QCISD/6-31++G(d,p) and CCSD(T)/6-31++G(d,p)//B3LYP/6-31++G(d,p) levels as well as by the DFT. The polarizable continuum model, at the B3LYP/6-31++G(d,p) level of theory, was used to study solvent effects on all the studied reactions. In solvent dichloromethane, all the initial cycloadducts 3 were obtained via direct ionic process as the result of the solvent effect. The consecutive [1,2]-shift reaction, in which intermediates 3 are rearranged to the five-membered heterocycles 4/5, is proved to be a kinetically controlled reaction, and the regioselectivity can be modulated by varying the migrant. The LOL function and RDG function based on localized electron analysis were used to analysis the covalent bond and noncovalent interactions in order to unravel the mechanism of the title reactions. PMID:22810049

  5. Stable Carbon Isotope Fractionation during Bacterial Acetylene Fermentation: Potential for Life Detection in Hydrocarbon-Rich Volatiles of Icy Planet(oid)s

    OpenAIRE

    Miller, Laurence G.; Baesman, Shaun M.; Oremland, Ronald S.

    2015-01-01

    Abstract We report the first study of stable carbon isotope fractionation during microbial fermentation of acetylene (C2H2) in sediments, sediment enrichments, and bacterial cultures. Kinetic isotope effects (KIEs) averaged 3.7 ± 0.5‰ for slurries prepared with sediment collected at an intertidal mudflat in San Francisco Bay and 2.7 ± 0.2‰ for a pure culture of Pelobacter sp. isolated from these sediments. A similar KIE of 1.8 ± 0.7‰ was obtained for methanogenic enrichments derived from sedi...

  6. Solution processed organic light-emitting diodes using the plasma cross-linking technology

    Science.gov (United States)

    He, Kongduo; Liu, Yang; Gong, Junyi; Zeng, Pan; Kong, Xun; Yang, Xilu; Yang, Cheng; Yu, Yan; Liang, Rongqing; Ou, Qiongrong

    2016-09-01

    Solution processed multilayer organic light-emitting diodes (OLEDs) present challenges, especially regarding dissolution of the first layer during deposition of a second layer. In this work, we first demonstrated a plasma cross-linking technology to produce a solution processed OLED. The surfaces of organic films can be cross-linked after mixed acetylene and Ar plasma treatment for several tens of seconds and resist corrosion of organic solvent. The film thickness and surface morphology of emissive layers (EMLs) with plasma treatment and subsequently spin-rinsed with chlorobenzene are nearly unchanged. The solution processed triple-layer OLED is successfully fabricated and the current efficiency increases 50% than that of the double-layer OLED. Fluorescent characteristics of EMLs are also observed to investigate factors influencing the efficiency of the triple-layer OLED. Plasma cross-linking technology may open up a new pathway towards fabrication of all-solution processed multilayer OLEDs and other soft electronic devices.

  7. Crossing Filaments

    CERN Document Server

    Filippov, Boris

    2011-01-01

    Solar filaments show the position of large scale polarity inversion lines and are used for the reconstruction of large-scale solar magnetic field structure on the basis of H{\\alpha} synoptic charts for the periods when magnetographic measurements were not available. Sometimes crossing filaments are seen in H{\\alpha} filtergrams. We analyze daily H{\\alpha} filtergrams from the archive of Big Bear Solar Observatory for the period of 1999-2003 to find crossing and interacting filaments. A number of examples are presented and filament patterns are compared with photospheric magnetic field distributions. We have found that all crossing filaments reveal quadrupolar magnetic configurations of the photospheric field and presume the presence of null points in the corona.

  8. X-H···π and X-H···N hydrogen bonds - Acetylene and hydrogen cyanide as proton acceptors

    International Nuclear Information System (INIS)

    The hydrogen-bonded systems were considered where acetylene or hydrogen cyanide acts as a proton acceptor and different proton donating molecules are taken into account. The B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) calculations were performed for the systems considered; for HCN···HF and C2H2···HF complexes various levels of approximation were applied up to CCSD(T)/6-311++G(3df,3pd)//CCSD/6-311++G(3df,3pd). The Quantum Theory of 'Atoms in Molecules' (QTAIM) was also applied. It was found that π-electrons of acetylene might act as the proton accepting centers and the found complex conformations are T-shaped ones. For hydrogen cyanide molecule the nitrogen atom acts as the proton acceptor center but not π-electrons. The characteristics of the bond critical points were also considered for the analyzed interactions and numerous correlations were found between geometrical, energetic and QTAIM parameters. The decomposition of the interaction energy for the systems analyzed was also applied.

  9. Reuse of waste sodium hypochlorite solution from the purification of acetylene%乙炔清净次氯酸钠废水的回用

    Institute of Scientific and Technical Information of China (English)

    唐红建; 秦明月

    2013-01-01

    Technologies for the treatment of waste sodium hypochlorite solution from acetylene purification process were introduced .Through adopting such methods as vacuum extraction ,oxida-tion ,flocculation ,precipitation ,and filtration ,acetylene dissolved in the waste sodium hypochlo-rite solution was recovered ;the contained impurities ,such as chlorides ,silicon ,phosphorus ,and magnesium ,were removed ;thus ,the hidden danger existed in the preparation of sodium hypochlo-rite solution was reduced as well as the influences on the production and quality of cement .%介绍了乙炔清净工序产生的次氯酸钠废水的处理技术,通过采用真空萃取、氧化、絮凝、沉淀、过滤等方法,回收了次氯酸钠废水中溶解的乙炔,去除了其中的氯化物、硅、硫、磷、镁等杂质,减少了次氯酸钠配制的安全隐患和对电石渣水泥生产及质量的影响。

  10. Full dimensional Franck-Condon factors for the acetylene A~ 1Au—X~1Σ+g  transition. I. Method for calculating polyatomic linear—bent vibrational intensity factors and evaluation of calculated intensities for the gerade vibrational modes in acetylene

    International Nuclear Information System (INIS)

    Franck-Condon vibrational overlap integrals for the A~1Au—X~1Σ+g transition in acetylene have been calculated in full dimension in the harmonic normal mode basis. The calculation uses the method of generating functions first developed for polyatomic Franck-Condon factors by Sharp and Rosenstock [J. Chem. Phys. 41(11), 3453–3463 (1964)], and previously applied to acetylene by Watson [J. Mol. Spectrosc. 207(2), 276–284 (2001)] in a reduced-dimension calculation. Because the transition involves a large change in the equilibrium geometry of the electronic states, two different types of corrections to the coordinate transformation are considered to first order: corrections for axis-switching between the Cartesian molecular frames and corrections for the curvilinear nature of the normal modes at large amplitude. The angular factor in the wave function for the out-of-plane component of the trans bending mode, ν4″, is treated as a rotation, which results in an Eckart constraint on the polar coordinates of the bending modes. To simplify the calculation, the other degenerate bending mode, ν5″, is integrated in the Cartesian basis and later transformed to the constrained polar coordinate basis, restoring the conventional v and l quantum numbers. An updated A~-state harmonic force field obtained recently in the R. W. Field research group is evaluated. The results for transitions involving the gerade vibrational modes are in qualitative agreement with experiment. Calculated results for transitions involving ungerade modes are presented in Paper II of this series [G. B. Park, J. H. Baraban, and R. W. Field, “Full dimensional Franck–Condon factors for the acetylene A~1Au—X~1Σ+g transition. II. Vibrational overlap factors for levels involving excitation in ungerade modes,” J. Chem. Phys. 141, 134305 (2014)

  11. Comparative study of the monomer grafting: ethylene, acetylene, 1,3-butadiene and estyrene in the matrix of recycled polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    In this study it is used the recycled polytetrafluoroethylene (PTFE), that with the gamma radiation under inert atmosphere or in presence of air, it is obtained free radicals and a posterior the monomer grafting (ethylene, acetylene, styrene or 1.3 butadiene), obtaining the copolymer polytetrafluoroethylene-g-monomer. It is studied the obtention of the polymer by two methods: by direct way, via grafting, where the polymer is irradiated in presence of monomer, and via grafting when the polymer is irradiated in absence of monomer and under inert or air. The characterization of the copolymer was performed by the techniques of infrared region absorption spectroscopy with Fourier transformation (FTIR), thermogravimetric (TGA) and derivative thermogravimetry (DTG), and percentage of mass grafting (DOG)

  12. Electrochemical behavior and voltammetric determination of vanillin based on an acetylene black paste electrode modified with graphene-polyvinylpyrrolidone composite film.

    Science.gov (United States)

    Deng, Peihong; Xu, Zhifeng; Zeng, Rongying; Ding, Chunxia

    2015-08-01

    The graphene-polyvinylpyrrolidone composite film modified acetylene black paste electrode (GR-PVP/ABPE) was fabricated and used to determine vanillin. In 0.1M H3PO4 solution, the oxidation peak current of vanillin increased significantly at GR-PVP/ABPE compared with bare ABPE, PVP/ABPE and GR/ABPE. The oxidation mechanism was discussed. The experimental conditions that exert influence on the voltammetric determination of vanillin, such as supporting electrolytes, pH values, accumulation potential and accumulation time, were optimized. Besides, the interference, repeatability, reproducibility and stability measurements were also evaluated. Under the optimal experimental conditions, the oxidation peak current was proportional to vanillin concentration in the range of 0.02-2.0 μM, 2.0-40 μM and 40-100 μM. The detection limit was 10nM. This sensor was used successfully for vanillin determination in various food samples.

  13. Acetylene weak bands at 2.5 $\\mu$m from intracavity Cr2+:ZnSe laser absorption observed with time-resolved Fourier transform spectroscopy

    CERN Document Server

    Girard, V; Sorokin, E; Sorokina, I T; Guelachvili, G; Picqué, N; Farrenq, Robert; Sorokin, Evgeni; Sorokina, Irina T.; Guelachvili, Guy; Picqu\\'{e}, Nathalie

    2006-01-01

    The spectral dynamics of a mid-infrared multimode Cr^2+:ZnSe laser located in a vacuum sealed chamber containing acetylene at low pressure is analyzed by a stepping-mode high-resolution time-resolved Fourier transform interferometer. Doppler-limited absorption spectra of C_2H_2 in natural isotopic abundance are recorded around 4000 cm^-1 with kilometric absorption path lengths and sensitivities better than 3 10^-8 cm-1. Two cold bands are newly identified and assigned to the n_1+n_4^1 and n_3+n_5^1 transitions of ^12C^13CH_2. The n_1+n_5^1 band of ^12C_2HD and fourteen ^12C_2H_2 bands are observed, among which for the first time n_2+2n_4^2+n_5^-1.

  14. In situ spectroscopic characterization of Ni1-xZnx/ZnO catalysts and their selectivity for acetylene semihydrogenation in excess ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Spanjers, Charles S.; Sim, Richard S.; Sturgis, Nicholas P.; Kabius, Bernd; Rioux, Robert M. (Penn State)

    2015-10-30

    The structures of ZnO-supported Ni catalysts were explored with in situ X-ray absorption spectroscopy, temperature-programmed reduction, X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy, and electron energy loss spectroscopy. Calcination of nickel nitrate on a nanoparticulate ZnO support at 450 °C results in the formation of Zn-doped NiO (ca. N₀̣̣₈₅ Zn₀̣̣₁₅O) nanoparticles with the rock salt crystal structure. Subsequent in situ reduction monitored by X-ray absorption near-edge structure (XANES) at the Ni K edge reveals a direct transformation of the Zn-doped NiO nanoparticles to a face-centered cubic alloy, Ni1-xZnx, at ~400 °C with x increasing with increasing temperature. Both in situ XANES and ex situ HRTEM provide evidence for intermetallic β₁-NiZn formation at ~550 °C. In comparison to a Ni/SiO₂ catalyst, Ni/ZnO necessitates a higher temperature for the reduction of NiII to Ni⁰, which highlights the strong interaction between Ni and the ZnO support. The catalytic activity for acetylene removal from an ethylene feed stream is decreased by a factor of 20 on Ni/ZnO in comparison to Ni/SiO₂. The decrease in catalytic activity of Ni/ZnO is accompanied by a reduced absolute selectivity to ethylene. H–D exchange measurements demonstrate a reduced ability of Ni/ZnO to dissociate hydrogen in comparison to Ni/SiO₂.These results of the catalytic experiments suggest that the catalytic properties are controlled, in part, by the zinc oxide support and stress the importance of reporting absolute ethylene selectivity for the catalytic semihydrogenation of acetylene in excess ethylene.

  15. Disciplinary Crossings.

    Science.gov (United States)

    Singh, Ilina

    2016-09-01

    Eighteen months ago, I left a permanent professorship in a generously interdisciplinary department of sociology and took an impermanent, lower-paying job at a university where I had to apply to something called the "Committee on Distinction" to retain the title of "Professor." Some people say, "That's what happens when Oxford calls." But it wasn't just that. It was the opportunity to engage in a groundbreaking experiment: to embed and integrate ethics within the Oxford Department of Psychiatry and Neuroscience. It's a dream job, for which I was willing to cross the disciplinary line into the medical sciences. In the United Kingdom, many bioethicists still work in departments outside science and medicine; similarly, those of us who work on neuroethics and psychiatric ethics tend to inhabit departments of philosophy, law, or sociology. I can report already that interdisciplinarity from this side feels and looks different. PMID:27649834

  16. Crossing Borders

    Directory of Open Access Journals (Sweden)

    Erik D. Barton, MD, MS, MBA

    2016-01-01

    Full Text Available As emergency physicians, we are privileged to be in a field that crosses more boundaries than any other medical specialty. It is a calling. Our skills are portable and transferable across cultural and geographic disparities. For these reasons, many of us are drawn to sharing our knowledge and training across the globe – towards treating patients in underserved and austere environments abroad. The rapid growth of international and global health educational initiatives across our U.S. residency training programs is a direct result of those undeniable forces. Additionally, inclusion of such rotations becomes a powerful resident recruitment tool as more and more of our trainees are looking for these opportunities during their formative years.

  17. Palladium-catalyzed double cross-coupling of E-vinylic dibromides with PhZnCl and the synthesis of tamoxifen

    Energy Technology Data Exchange (ETDEWEB)

    Pilli, Ronaldo A.; Robello, Luis Gustavo [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica]. E-mail: pilli@iqm.unicamp.br

    2004-12-01

    (E)-1,2-vinylic dibromides 11a-f were stereoselectively prepared via bromination of acetylenic compounds with pyridinium tribromide in MeOH/CCl{sub 4} at low temperature and double cross-coupled with PhZnCl under Pd(0) catalysis (Negishi protocol) to afford tri- and tetrasubstituted olefins 14a-e. Tamoxifen, a selective estrogen receptor modulator clinically prescribed in breast cancer therapy, was prepared in 7 steps and 30% overall yield from 4-iodophenol (3) as a 2.3:1 mixture of (Z)- and (E)-isomers. (author)

  18. Electron swarm parameters in pure C2H2 and in C2H2-Ar mixtures and electron collision cross sections for the C2H2 molecule

    Science.gov (United States)

    Nakamura, Yoshiharu

    2010-09-01

    Electron swarm parameters (the drift velocity and the longitudinal diffusion coefficient) were measured in pure C2H2 and also in C2H2-Ar mixtures containing 0.517% and 5.06% acetylene over wide E/N ranges. These swarm parameters were analysed using a Boltzmann equation analysis and a set of electron collision cross sections for the C2H2 molecule was derived so that it was consistent with the present swarm data and published ionization coefficient. The present result suggested the presence of a Ramsauer-Townsend minimum in the elastic momentum transfer cross section at 0.08 eV and prominent threshold and resonance peaks in the ν4/ν5 vibrational excitation cross section. The present cross section set was also confirmed to be consistent with the published experimental total cross section of C2H2.

  19. Effect of Solvent and Acid-Base on Palladium(ll)-catalyzed Dicarbonylation of Terminal Acetylenes: a General, Efficient andStereoselective Synthesis of Maleic Diesters and Maleic Anhydrides

    Institute of Scientific and Technical Information of China (English)

    JIANG, Huan-Feng; LI, JiN-Heng; CHEN, Ming-Cai

    2001-01-01

    The productions of maleic diesters and maleic anhydrises depend on the effect of solvint and acid-bade of solvent and acid-base in palladium-catalyzed dicarbonylation of terminal acetylenes. For primaryand secondary alcohol in benzene.only maleic diesters wereobtained stereospecifically from the sicabonylation ofacetylenes in the presence of PdCl2,and NaHCO3.For tERTIARy alcohols,maleic anhydrides were synthesized selectively.

  20. Extraordinary Separation of Acetylene-Containing Mixtures with Microporous Metal-Organic Frameworks with Open O Donor Sites and Tunable Robustness through Control of the Helical Chain Secondary Building Units.

    Science.gov (United States)

    Yao, Zizhu; Zhang, Zhangjing; Liu, Lizhen; Li, Ziyin; Zhou, Wei; Zhao, Yunfeng; Han, Yu; Chen, Banglin; Krishna, Rajamani; Xiang, Shengchang

    2016-04-11

    Acetylene separation is a very important but challenging industrial separation task. Here, through the solvothermal reaction of CuI and 5-triazole isophthalic acid in different solvents, two metal-organic frameworks (MOFs, FJU-21 and FJU-22) with open O donor sites and controllable robustness have been obtained for acetylene separation. They contain the same paddle-wheel {Cu2(COO2)4} nodes and metal-ligand connection modes, but with different helical chains as secondary building units (SBUs), leading to different structural robustness for the MOFs. FJU-21 and FJU-22 are the first examples in which the MOFs' robustness is controlled by adjusting the helical chain SBUs. Good robustness gives the activated FJU-22 a, which has higher surface area and gas uptakes than the flexible FJU-21 a. Importantly, FJU-22 a shows extraordinary separation of acetylene mixtures under ambient conditions. The separation capacity of FJU-22 a for 50:50 C2H2/CO2 mixtures is about twice that of the high-capacity HOF-3, and its actual separation selectivity for C2H2/C2H4 mixtures containing 1% acetylene is the highest among reported porous materials. Based on first-principles calculations, the extraordinary separation performance of C2H2 for FJU-22 a was attributed to hydrogen-bonding interactions between the C2H2 molecules with the open O donors on the wall, which provide better recognition ability for C2H2 than other functional sites, including open metal sites and amino groups.

  1. Extraordinary Separation of Acetylene-Containing Mixtures with Microporous Metal-Organic Frameworks with Open O Donor Sites and Tunable Robustness through Control of the Helical Chain Secondary Building Units

    KAUST Repository

    Yao, Zizhu

    2016-03-02

    Acetylene separation is a very important but challenging industrial separation task. Here, through the solvothermal reaction of CuI and 5-triazole isophthalic acid in different solvents, two metal-organic frameworks (MOFs, FJU-21 and FJU-22) with open O donor sites and controllable robustness have been obtained for acetylene separation. They contain the same paddle-wheel {Cu2(COO2)4} nodes and metal-ligand connection modes, but with different helical chains as secondary building units (SBUs), leading to different structural robustness for the MOFs. FJU-21 and FJU-22 are the first examples in which the MOFs\\' robustness is controlled by adjusting the helical chain SBUs. Good robustness gives the activated FJU-22 a, which has higher surface area and gas uptakes than the flexible FJU-21 a. Importantly, FJU-22 a shows extraordinary separation of acetylene mixtures under ambient conditions. The separation capacity of FJU-22 a for 50:50 C2H2/CO2 mixtures is about twice that of the high-capacity HOF-3, and its actual separation selectivity for C2H2/C2H4 mixtures containing 1 % acetylene is the highest among reported porous materials. Based on first-principles calculations, the extraordinary separation performance of C2H2 for FJU-22 a was attributed to hydrogen-bonding interactions between the C2H2 molecules with the open O donors on the wall, which provide better recognition ability for C2H2 than other functional sites, including open metal sites and amino groups. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Border Crossing/Entry Data - Boarder Crossing

    Data.gov (United States)

    Department of Transportation — Border Crossing/Entry Data provides summary statistics for incoming crossings at the U.S.-Canadian and the U.S.-Mexican border at the port level. Data are available...

  3. Differences of cardiac output measurements by open-circuit acetylene uptake in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a cohort study

    Directory of Open Access Journals (Sweden)

    Schwaiblmair Martin

    2012-03-01

    Full Text Available Abstract Background As differences in gas exchange between pulmonary arterial hypertension (PAH and chronic thromboembolic pulmonary hypertension (CTEPH have been demonstrated, we asked if cardiac output measurements determined by acetylene (C2H2 uptake significantly differed in these diseases when compared to the thermodilution technique. Method Single-breath open-circuit C2H2 uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients. Results In PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min. In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min. Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p 2 gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p Conclusion Cardiac output evaluation by the C2H2 technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH.

  4. Acetylene Black Induced Heterogeneous Growth of Macroporous CoV2O6 Nanosheet for High-Rate Pseudocapacitive Lithium-Ion Battery Anode.

    Science.gov (United States)

    Zhang, Lei; Zhao, Kangning; Luo, Yanzhu; Dong, Yifan; Xu, Wangwang; Yan, Mengyu; Ren, Wenhao; Zhou, Liang; Qu, Longbing; Mai, Liqiang

    2016-03-23

    Metal vanadates suffer from fast capacity fading in lithium-ion batteries especially at a high rate. Pseudocapacitance, which is associated with surface or near-surface redox reactions, can provide fast charge/discharge capacity free from diffusion-controlled intercalation processes and is able to address the above issue. In this work, we report the synthesis of macroporous CoV2O6 nanosheets through a facile one-pot method via acetylene black induced heterogeneous growth. When applied as lithium-ion battery anode, the macroporous CoV2O6 nanosheets show typical features of pseudocapacitive behavior: (1) currents that are mostly linearly dependent on sweep rate and (2) redox peaks whose potentials do not shift significantly with sweep rate. The macroporous CoV2O6 nanosheets display a high reversible capacity of 702 mAh g(-1) at 200 mA g(-1), excellent cyclability with a capacity retention of 89% (against the second cycle) after 500 cycles at 500 mA g(-1), and high rate capability of 453 mAh g(-1) at 5000 mA g(-1). We believe that the introduction of pseudocapacitive properties in lithium battery is a promising direction for developing electrode materials with high-rate capability.

  5. Triel Bonds, π-Hole-π-Electrons Interactions in Complexes of Boron and Aluminium Trihalides and Trihydrides with Acetylene and Ethylene.

    Science.gov (United States)

    Grabowski, Sławomir J

    2015-06-19

    MP2/aug-cc-pVTZ calculations were performed on complexes of aluminium and boron trihydrides and trihalides with acetylene and ethylene. These complexes are linked through triel bonds where the triel center (B or Al) is characterized by the Lewis acid properties through its π-hole region while π-electrons of C2H2 or C2H4 molecule play the role of the Lewis base. Some of these interactions possess characteristics of covalent bonds, i.e., the Al-π-electrons links as well as the interaction in the BH3-C2H2 complex. The triel-π-electrons interactions are classified sometimes as the 3c-2e bonds. In the case of boron trihydrides, these interactions are often the preliminary stages of the hydroboration reaction. The Quantum Theory of "Atoms in Molecules" as well as the Natural Bond Orbitals approach are applied here to characterize the π-hole-π-electrons interactions.

  6. A near-infrared acetylene detection system based on a 1.534 μm tunable diode laser and a miniature gas chamber

    Science.gov (United States)

    He, Qixin; Zheng, Chuantao; Liu, Huifang; Li, Bin; Wang, Yiding; Tittel, Frank K.

    2016-03-01

    A near-infrared (NIR) dual-channel differential acetylene (C2H2) detection system was experimentally demonstrated based on tunable diode laser absorption spectroscopy (TDLAS) technique and wavelength modulation spectroscopy (WMS) technique. A distributed feedback (DFB) laser modulated by a self-developed driver around 1.534 μm is used as light source. A miniature gas chamber with 15 cm path length is adopted as absorption pool, and an orthogonal lock-in amplifier is developed to extract the second harmonic (2f) signal. Sufficient standard C2H2 samples with different concentrations were prepared, and detailed measurements were carried out to study the detection performance. A good linear relationship is observed between the amplitude of the 2f signal and C2H2 concentration within the range of 200-10,000 ppm, and the relative measurement error is less than 5% within the whole range. A long-term monitoring lasting for 20 h on a 1000 ppm C2H2 sample was carried out, and the maximum concentration fluctuation is less than 2%. Due to the capability of using long-distance and low-loss optical fiber, the gas-cell can be placed in the filed for remote monitoring, which enables the system to have good prospects in industrial field.

  7. Stable carbon isotope fractionation during bacterial acetylene fermentation: Potential for life detection in hydrocarbon-rich volatiles of icy planet(oid)s

    Science.gov (United States)

    Miller, Laurence; Baesman, Shaun; Oremland, Ron

    2015-01-01

    We report the first study of stable carbon isotope fractionation during microbial fermentation of acetylene (C2H2) in sediments, sediment enrichments, and bacterial cultures. Kinetic isotope effects (KIEs) averaged 3.7 ± 0.5‰ for slurries prepared with sediment collected at an intertidal mudflat in San Francisco Bay and 2.7 ± 0.2‰ for a pure culture of Pelobacter sp. isolated from these sediments. A similar KIE of 1.8 ± 0.7‰ was obtained for methanogenic enrichments derived from sediment collected at freshwater Searsville Lake, California. However, C2H2 uptake by a highly enriched mixed culture (strain SV7) obtained from Searsville Lake sediments resulted in a larger KIE of 9.0 ± 0.7‰. These are modest KIEs when compared with fractionation observed during oxidation of C1 compounds such as methane and methyl halides but are comparable to results obtained with other C2compounds. These observations may be useful in distinguishing biologically active processes operating at distant locales in the Solar System where C2H2 is present. These locales include the surface of Saturn's largest moon Titan and the vaporous water- and hydrocarbon-rich jets emanating from Enceladus.

  8. Electrochemical characterization of the LiCoO{sub 2}/acetylene carbon ratios for porous electrodes in alkaline lithium aqueous solutions by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, H., E-mail: castanedah@battelle.or [Battelle Memorial Institute, 505 King Avenue, Columbus OH, 43201 (United States); Tan, B.; Saunders, J. [Battelle Memorial Institute, 505 King Avenue, Columbus OH, 43201 (United States)

    2010-05-01

    LiCoO{sub 2} electrodes were fabricated with different acetylene carbon (AC) additions and fixed binder content. Subsequent electrochemical testing showed different processes at the interface that are related to pore distribution and electrode composition. Electrochemical impedance spectroscopy characterized the mechanisms close to open circuit conditions. The active state, combined with diffusion mechanisms within the cylindrical pores, contributed to the functionality of the particles according to the LiCoO{sub 2}/AC content, and surface characteristics of the electrode influenced the impedance distribution. The de Levie theory for porous electrode was used to describe the influence of the LiCoO{sub 2}/AC ratios in the impedance distribution when exposed to alkaline aqueous electrolytes (LiOH + Li{sub 2}SO{sub 4}). The pore model helped relate physical properties of the composite material, such as pore count, pore length, and double layer capacitance, with the mechanisms present at the interface. The theoretical model was validated with experimental data and the fitting process resulted in good agreement.

  9. Process analysis of effluent hydrocarbon recycling for coal pyrolysis to acetylene in thermal plasma%热等离子体煤制乙炔裂解气烃类循环过程分析

    Institute of Scientific and Technical Information of China (English)

    程炎; 颜彬航; 李天阳; 程易

    2015-01-01

    针对等离子体煤裂解制乙炔过程,提出了将过程裂解气中副产的烃类分离,循环输入等离子体反应器的新型工艺流程。基于新疆天业2 MW示范平台装置的典型运行参数,采用热力学分析手段,理论上分析了该工艺流程对于体系乙炔产量、单位质量乙炔煤耗和裂解电耗等的影响。结果表明,裂解气烃类循环可以有效提高裂解气中乙炔浓度和产率,同时减少煤粉输送气等流程气体的使用。典型操作条件下,采用裂解气烃类循环工艺可以增加35.6%的乙炔收率和13.4%的氢气收率,降低30%的单位乙炔煤耗和裂解电耗,是高效可行的优化方案。%Coal pyrolysis via thermal plasma provides an alternative path to realize the effective conversion from coal to acetylene. Recycling the hydrocarbons in the effluent gas to the plasma pyrolysis process is proposed in this work to improve the reactor performance. Thermodynamic analysis is made as the reference on the basis of the pilot-plant results of Xinjiang Tianye 2 MW plasma pyrolysis device. The comparison results show that the recycling of effluent hydrocarbons (except acetylene) can raise the volume fraction and mass flow rate of acetylene in the product gas. The hydrocarbons in cracked gas is ample to be used as the conveying and accelerating gas for coal and the protecting gas for plasma torch, which can reduce the input amount of working gas and optimize the whole gas flow of the process. Different optimization cases are discussed to compare the products (i.e., acetylene and hydrogen) output and the gas input of the thermal plasma pyrolysis system. The optimized results show that the recycling process is feasible and effective, with reduced coal consumption (30%) and pyrolysis energy consumption (30%) as well as increased acetylene yield (35.6%).

  10. Acetylene inhibition of N2O reduction in laboratory soil and groundwater denitrification assays: evaluation by 15N tracer and 15N site preference of N2O

    Science.gov (United States)

    Weymann, Daniel; Well, Reinhard; Lewicka-Szczebak, Dominika; Lena, Rohe

    2013-04-01

    The measurement of denitrification in soils and aquifers is still challenging and often enough associated with considerable experimental effort and high costs. Against this background, the acetylene inhibition technique (AIT) applied in laboratory soil and groundwater denitrification assays is by far the most effective approach. However, this method has been largely criticized, as it is susceptible to underestimate denitrification rates and adds an additional carbon source to the substrates to be investigated. Here we provide evidence that the AIT is not necessarily an inappropriate approach to measure denitrification, that its reliability depends on the drivers governing the process, and that the 15N site preference of N2O (SP) may serve as a tool to assess this reliability. Two laboratory batch experiments were conducted, where sandy aquifer material and a peat soil were incubated as slurries. We established (i) a standard anaerobic treatment by adding KNO3 (10 mg N L-1), (ii) an oxygen treatment by adding KNO3 and O2 (5 mg L-1), and (iii) a glucose treatment by adding KNO3 supplemented with glucose (200 mg C L-1). Both experiments were run under 10 % (v/v) acetylene atmosphere and as 15N tracer treatments using labeled K15NO3 (60 atom % 15N). In the case of the standard anaerobic treatments, we found a very good agreement of denitrification potential obtained by the AIT and 15N tracer methods. SP of N2O of the AIT samples from this treatment ranged between -4.8 and 2.6 ‰ which is indicative for N2O production during bacterial denitrification but not for N2O reduction to N2. In contrast, we observed substantial underestimation of denitrification by AIT for the glucose treatments compared to the 15N method, i.e. denitrification was underestimated by 36 % (sandy aquifer material) and 47 % (peat soil). SP of N2O of the AIT samples from this treatment ranged between 4.5 and 9.6 ‰, which suggests occurrence of bacterial N2O reduction. In the case of the oxygen

  11. Secondary Organic Aerosol Formation from Acetylene (C2H2: seed effect on SOA yields due to organic photochemistry in the aerosol aqueous phase

    Directory of Open Access Journals (Sweden)

    P. J. Ziemann

    2009-03-01

    Full Text Available The lightest Non Methane HydroCarbon (NMHC, i.e., acetylene (C2H2 is found to form secondary organic aerosol (SOA. Contrary to current belief, the number of carbon atoms, n, for a NMHC to act as SOA precursor is lowered to n=2 here. The OH-radical initiated oxidation of C2H2 forms glyoxal (CHOCHO as the highest yield product, and >99% of the SOA from C2H2 is attributed to CHOCHO. SOA formation from C2H2 and CHOCHO was studied in a photochemical and a dark simulation chamber. Further, the experimental conditions were varied with respect to the chemical composition of the seed aerosols, mild acidification with sulphuric acid (SA, 3

  12. Vibration-rotation alchemy in acetylene (12C2H2), ? at low vibrational excitation: from high resolution spectroscopy to fast intramolecular dynamics

    Science.gov (United States)

    Perry, David S.; Miller, Anthony; Amyay, Badr; Fayt, André; Herman, Michel

    2010-04-01

    The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene (12C2H2), ? with up to 8600 cm-1 of vibrational energy. This comparison is based on the extensive and reliable knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision [B. Amyay, S. Robert, M. Herman, A. Fayt, B. Raghavendra, A. Moudens, J. Thiévin, B. Rowe, and R. Georges, J. Chem. Phys. 131, 114301 (2009)]. Simulated intensity borrowing features in high resolution absorption spectra and predicted survival probabilities in intramolecular vibrational redistribution (IVR) are first investigated for the v 4 + v 5 and v 3 bright states, for J = 2, 30 and 100. The dependence of the results on the rotational quantum number and on the choice of vibrational bright state reflects the interplay of three kinds of off-diagonal resonances: anharmonic, rotational l-type, and Coriolis. The dynamical quantities used to characterize the calculated time-dependent dynamics are the dilution factor φ d, the IVR lifetime τ IVR , and the recurrence time τ rec. For the two bright states v 3 + 2v 4 and 7v 4, the collisionless dynamics for thermally averaged rotational distributions at T = 27, 270 and 500 K were calculated from the available spectroscopic data. For the 7v 4 bright state, an apparent irreversible decay of is found. In all cases, the model Hamiltonian allows a detailed calculation of the energy flow among all of the coupled zeroth-order vibration-rotation states.

  13. Non-covalent C-Cl…π interaction in acetylene-carbon tetrachloride adducts: Matrix isolation infrared and ab initio computational studies

    Science.gov (United States)

    Ramanathan, N.; Sundararajan, K.; Vidya, K.; Jemmis, Eluvathingal D.

    2016-03-01

    Non-covalent halogen-bonding interactions between π cloud of acetylene (C2H2) and chlorine atom of carbon tetrachloride (CCl4) have been investigated using matrix isolation infrared spectroscopy and quantum chemical computations. The structure and the energies of the 1:1 C2H2-CCl4 adducts were computed at the B3LYP, MP2 and M05-2X levels of theory using 6-311 ++G(d,p) basis set. The computations indicated two minima for the 1:1 C2H2-CCl4 adducts; with the C-Cl…π adduct being the global minimum, where π cloud of C2H2 is the electron donor. The second minimum corresponded to a C-H…Cl adduct, in which C2H2 is the proton donor. The interaction energies for the adducts A and B were found to be nearly identical. Experimentally, both C-Cl…π and C-H…Cl adducts were generated in Ar and N2 matrixes and characterized using infrared spectroscopy. This is the first report on halogen bonded adduct, stabilized through C-Cl…π interaction being identified at low temperatures using matrix isolation infrared spectroscopy. Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) analyses were performed to support the experimental results. The structures of 2:1 ((C2H2)2-CCl4) and 1:2 (C2H2-(CCl4)2) multimers and their identification in the low temperature matrixes were also discussed.

  14. Characteristics of Carbon Material Formation on SBA-15 and Ni-SBA-15 Templates by Acetylene Decomposition and Their Bioactivity Effects

    Directory of Open Access Journals (Sweden)

    Hsiu-Mei Chiang

    2016-05-01

    Full Text Available Carbon spheres and tubes were formed from acetylene decomposition on SBA-15 and Ni-SBA-15 at 650–850 °C. At 650 °C, the decomposed carbons covered the surface of the support, and no carbon spheres and filament materials were formed. Carbon sphere formation occurred at 750 °C–850 °C; with diameters ranging from 0.8 μm–1.1 μm. For Ni-SBA-15, the diameters of the spheres and filaments were 0.8 μm and 62 nm, respectively, at 650 °C. At 750 °C, the diameter of the ball carbon materials ranged from 0.7 μm–0.8 μm, the diameter of the carbon tubes formed was 120–130 nm, and their pore diameter was 8.0 nm–11 nm. At 850 °C, the diameters of ball carbon materials and carbon tubes were similar to those of the materials at the formation temperature, 750 °C. Si, O and C were the main constituents of SBA-15; Ni-SBA-15 and carbon material formation supports. High-ring PAHs (such as BaP (five rings; IND (six rings; DBA (five rings and B[ghi]P (six rings exist in carbon materials. SBA-15 revealed insignificant cytotoxicity, but Ni-SBA-15 inhibited the proliferation of human lung cancer cells (A549. Less inhibition on cell viability and reactive oxidative species (ROS generation on A549 were determined for carbon material formation on the Ni-SBA-15 compared to the Ni-SBA-15.

  15. Mid-IR Absorption Cross-Section Measurements of Hydrocarbons

    KAUST Repository

    Alrefae, Majed Abdullah

    2013-05-01

    Laser diagnostics are fast-response, non-intrusive and species-specific tools perfectly applicable for studying combustion processes. Quantitative measurements of species concentration and temperature require spectroscopic data to be well-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform Infrared (FTIR) spectrometer, tunable Difference Frequency Generation laser and fixed wavelength helium-neon laser. The studied species are methane, methanol, acetylene, ethylene, ethane, ethanol, propylene, propane, 1-butene, n-butane, n-pentane, n-hexane, and n-heptane. The Fourier Transform Infrared (FTIR) spectrometer is used for the measurements of the absorption cross-sections and the integrated band intensities of the 13 hydrocarbons. The spectral region of the spectra is 2800 – 3400 cm-1 (2.9 – 3.6 μm) and the temperature range is 673 – 1100 K. These valuable data provide huge opportunities to select interference-free wavelengths for measuring time-histories of a specific species in a shock tube or other combustion systems. Such measurements can allow developing/improving chemical kinetics mechanisms by experimentally determining reaction rates. The Difference Frequency Generation (DFG) laser is a narrow line-width, tunable laser in the 3.35 – 3.53 μm wavelength region which contains strong absorption features for most hydrocarbons due to the fundamental C-H vibrating stretch. The absorption cross-sections of propylene are measured at seven different wavelengths using the DFG laser. The temperature range is 296 – 460 K which is reached using a Reflex Cell. The DFG laser is very attractive for kinetic studies in the shock tube because of its fast time response and the potential possibility of making species-specific measurements. The Fixed wavelength

  16. Gaseous nitrogen losses from field plots grown with pea (Pisum sativum L.) or spring barley (Hordeum vulgare L.) estimated by 15N mass balance and acetylene inhibition techniques

    DEFF Research Database (Denmark)

    Bertelsen, F.; Jensen, E.S.

    1992-01-01

    by the acetylene-inhibition technique were negligible. A substantial amount of fertilizer N was unaccounted for by the N-15 mass balance, especially in the pea plots. The loss took place during the period of grain-filling in which no leaching occurred, and was accompanied by a decrease in N-15 content...... of the plants. Volatilization of ammonia from the aerial parts of the plants is a possible explanation of the observed loss. An estimation of denitrification relying only on the N-15 mass balance would have resulted in an overestimation of denitrification....

  17. Novel mode of 2-fold interpenetration observed in a primitive cubic network of formula [Ni(1,2-bis(4-pyridyl)acetylene)2(Cr2O7)]n.

    Science.gov (United States)

    Scott, Hayley S; Bajpai, Alankriti; Chen, Kai-Jie; Pham, Tony; Space, Brian; Perry, John J; Zaworotko, Michael J

    2015-10-14

    A primitive cubic (pcu) network of formula [Ni(1,2-bis(4-pyridyl)acetylene)2(Cr2O7)]n, , has been synthesised and found to exhibit a novel type of inclined 2-fold interpenetration and an isosteric heat of adsorption (Q(st)) of 30.5 kJ mol(-1) towards CO2 at zero loading. Q(st) is relatively high in the broad context but less than that observed in related hybrid ultramicroporous materials, a feature that can be understood after studying pore structure and molecular simulations of CO2 adsorption. PMID:26307270

  18. FEMA DFIRM Cross Sections

    Data.gov (United States)

    Minnesota Department of Natural Resources — FEMA Cross Sections are required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally...

  19. American Red Cross

    Science.gov (United States)

    ... to Help Sand Fire Evacuees » 90% of the Red Cross Workforce are Volunteers Learn More. Search for ... Volunteer» Digital Advocates» SEARCH FOR OPENINGS Shop the Red Cross Store Be Prepared and Ready to Respond ...

  20. Smart pedestrian crossings

    OpenAIRE

    Štrumbelj, Martin

    2016-01-01

    Dissertation presents smart pedestrian crossings which could be installed in road infrastructure in the future. Because of too frequent road accidents in the areas of road crossings and heightened regulations on harmful emissions and annual increasing of traffic, smart pedestrian crossings are appropriate solution, which is used by many of countries throughout the world. The fact that in Slovenia the preposition for the technical specifications of crossings is still in preparation is responsi...

  1. Electron and Positron Scattering with a Few Alkyne Molecules - Theoretical Cross sections

    Science.gov (United States)

    Patel, U. R.; Joshipura, K. N.; Kothari, H. N.

    2016-05-01

    Electron molecule scattering processes play an important role in the understanding of the electron driven physiochemical phenomena in diverse environments such as biological media, planetary atmospheres, interstellar clouds and plasmas. In modeling and simulating effects induced by electrons traversing through matter, the relevant cross section data are required as an input. An alternative probe, positron has also been used for the similar study of atoms, molecules and matter in bulk. Interaction of positrons with atoms and molecules differs from electron interactions due to opposite sign of charge and absence of exchange potential. In the present paper, our aim is to apply an identical theoretical method1,2 to electrons as well as positrons interacting with alkyne molecules like acetylene (HC ≡ CH), 1- Butyne (HC ≡ C- CH2 CH3) and Propyne (HC ≡ C- CH3) . We have carried out calculations of total scattering cross sections by starting with complex potential approach followed by the solution of the Schrodinger equation using numerical method. Ionization cross sections are deduced as in1,2. Comparisons have been made with available theoretical and experimental results for both electron (e-) and positron (e+) . The study will be extended to alkanes and alkenes.

  2. Pharmacokinetics and pharmacodynamics of orally administered acetylenic tricyclic bis(cyanoenone), a highly potent Nrf2 activator with a reversible covalent mode of action

    Energy Technology Data Exchange (ETDEWEB)

    Kostov, Rumen V.; Knatko, Elena V.; McLaughlin, Lesley A.; Henderson, Colin J. [Jacqui Wood Cancer Centre, Division of Cancer Research, Medical Research Institute, University of Dundee, Dundee, DD1 9SY, Scotland (United Kingdom); Zheng, Suqing [Department of Chemistry and Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY, 11794 (United States); Huang, Jeffrey T.-J. [Jacqui Wood Cancer Centre, Division of Cancer Research, Medical Research Institute, University of Dundee, Dundee, DD1 9SY, Scotland (United Kingdom); Honda, Tadashi [Department of Chemistry and Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY, 11794 (United States); Dinkova-Kostova, Albena T., E-mail: a.dinkovakostova@dundee.ac.uk [Jacqui Wood Cancer Centre, Division of Cancer Research, Medical Research Institute, University of Dundee, Dundee, DD1 9SY, Scotland (United Kingdom); Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205 (United States); Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205 (United States)

    2015-09-25

    The acetylenic tricyclic bis(cyanoenone) TBE-31 is a highly potent cysteine targeting compound with a reversible covalent mode of action; its best-characterized target being Kelch-like ECH-associated protein-1 (Keap1), the cellular sensor for oxidants and electrophiles. TBE-31 reacts with cysteines of Keap1, impairing its ability to target nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) for degradation. Consequently, Nrf2 accumulates and orchestrates cytoprotective gene expression. In this study we investigated the pharmacokinetic and pharmacodynamic properties of TBE-31 in C57BL/6 mice. After a single oral dose of 10 μmol/kg (∼200 nmol/animal), the concentration of TBE-31 in blood exhibited two peaks, at 22.3 nM and at 15.5 nM, 40 min and 4 h after dosing, respectively, as determined by a quantitative stable isotope dilution LC-MS/MS method. The AUC{sub 0–24h} was 195.5 h/nmol/l, the terminal elimination half-life was 10.2 h, and the k{sub el} was 0.068 h{sup −1}. To assess the pharmacodynamics of Nrf2 activation by TBE-31, we determined the enzyme activity of its prototypic target, NAD(P)H:quinone oxidoreductase 1 (NQO1) and found it elevated by 2.4- and 1.5-fold in liver and heart, respectively. Continuous feeding for 18 days with diet delivering the same daily doses of TBE-31 under conditions of concurrent treatment with the immunosuppressive agent azathioprine had a similar effect on Nrf2 activation without any indications of toxicity. Together with previous reports showing the cytoprotective effects of TBE-31 in animal models of carcinogenesis, our results demonstrate the high potency, efficacy and suitability for chronic administration of cysteine targeting reversible covalent drugs. - Highlights: • TBE-31 is a cysteine targeting compound with a reversible covalent mode of action. • After a single oral dose, the blood concentration of TBE-31 exhibits two peaks. • Oral TBE-31 is a potent activator of Nrf2-dependent enzymes in

  3. Pharmacokinetics and pharmacodynamics of orally administered acetylenic tricyclic bis(cyanoenone), a highly potent Nrf2 activator with a reversible covalent mode of action

    International Nuclear Information System (INIS)

    The acetylenic tricyclic bis(cyanoenone) TBE-31 is a highly potent cysteine targeting compound with a reversible covalent mode of action; its best-characterized target being Kelch-like ECH-associated protein-1 (Keap1), the cellular sensor for oxidants and electrophiles. TBE-31 reacts with cysteines of Keap1, impairing its ability to target nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) for degradation. Consequently, Nrf2 accumulates and orchestrates cytoprotective gene expression. In this study we investigated the pharmacokinetic and pharmacodynamic properties of TBE-31 in C57BL/6 mice. After a single oral dose of 10 μmol/kg (∼200 nmol/animal), the concentration of TBE-31 in blood exhibited two peaks, at 22.3 nM and at 15.5 nM, 40 min and 4 h after dosing, respectively, as determined by a quantitative stable isotope dilution LC-MS/MS method. The AUC0–24h was 195.5 h/nmol/l, the terminal elimination half-life was 10.2 h, and the kel was 0.068 h−1. To assess the pharmacodynamics of Nrf2 activation by TBE-31, we determined the enzyme activity of its prototypic target, NAD(P)H:quinone oxidoreductase 1 (NQO1) and found it elevated by 2.4- and 1.5-fold in liver and heart, respectively. Continuous feeding for 18 days with diet delivering the same daily doses of TBE-31 under conditions of concurrent treatment with the immunosuppressive agent azathioprine had a similar effect on Nrf2 activation without any indications of toxicity. Together with previous reports showing the cytoprotective effects of TBE-31 in animal models of carcinogenesis, our results demonstrate the high potency, efficacy and suitability for chronic administration of cysteine targeting reversible covalent drugs. - Highlights: • TBE-31 is a cysteine targeting compound with a reversible covalent mode of action. • After a single oral dose, the blood concentration of TBE-31 exhibits two peaks. • Oral TBE-31 is a potent activator of Nrf2-dependent enzymes in multiple organs.

  4. Essays on cross listings

    OpenAIRE

    Λουκά, Χριστόδουλος; Louca, Christodoulou

    2006-01-01

    This PhD dissertation consists of three essays on cross listings: a. The Operating Performance of Exchange-Listed American Depositary Receipts. b. Cross Listing, Bonding and Corporate Governance. c. Cross Listing on U.S. Stock Exchanges and the Earnings Management Hypothesis. The questions analyzed in this dissertation arise because of possible frictions in the transition of information from corporations to markets. To overcome informational frictions a company might choose to lis...

  5. Cross resonant optical antenna.

    Science.gov (United States)

    Biagioni, P; Huang, J S; Duò, L; Finazzi, M; Hecht, B

    2009-06-26

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  6. Surrogate model of acetylene hydrogenation reactor based on bootstrap GEI algorithm%基于bootstrap GEI算法的碳二加氢反应器代理模型

    Institute of Scientific and Technical Information of China (English)

    段星辰; 杜文莉

    2015-01-01

    Acetylene hydrogenation reactor is an important device of the ethylene plant, and its working condition directly affects the purity and yield of ethylene products, so it is of great significance to improve the modeling and optimization efficiency of the reaction process for acetylene hydrogenation. However, directly optimizing high precision CFD models are often low efficiency because of the large calculation. This paper from the model accuracy of prediction variance and improvement of the effectiveness of global search, proposes a bootstrap GEI algorithm based on Kriging surrogate model. Through simulation contrast of test functions, compared with bootstrap EI algorithm, this algorithm can find the optimal sample points of global search and reduce the number of sample points, so as to improve the efficiency of the model updating and optimization. And this algorithm is effectively validated in the surrogate model of acetylene hydrogenation reactor.%碳二加氢反应器是乙烯工厂的一个重要装置,其运行状况直接影响着乙烯产品的纯度和产量,因此,提高碳二加氢反应过程的建模和优化效率对于工业实际具有重要意义.但是,直接对碳二加氢反应器的CFD高精度分析模型进行优化,计算量大,优化效率非常低.本文从模型预测方差准确性和提高全局搜索的有效性出发,基于Kriging代理模型,提出了一种求取无偏预测方差的广义期望提高算法——bootstrap GEI算法,通过测试函数的仿真对比,与bootstrap EI算法相比,该算法能够从全局角度搜索最优样本点,减少样本点的个数,从而提高模型更新和优化效率.该算法在实际工业碳二加氢等温反应器的代理模型中也得到了有效验证.

  7. Clinical Research of Desogestrel Acetylene Estrone Be Used for Artificial Abortion Postoperative%去氧孕烯炔雌醇片用于人工流产术后的临床研究

    Institute of Scientific and Technical Information of China (English)

    尹佳苓; 宋文侠

    2016-01-01

    目的:探究人工流产术后即刻为患者口服去氧孕烯炔雌醇片(妈富隆)的临床效果。方法择取2013年10月~2015年12月我院产科人工流产手术患者220例作为研究对象,将患者随机分成研究组和对照组,每组各110例。研究组患者在人工流产术后立即口服妈富隆,抗生素,以及益母草颗粒,对照组患者术后仅服用抗生素和益母草颗粒,比较两组患者的临床疗效。结果研究组患者在阴道流血量、阴道流血持续时间、月经周期恢复情况、并发症发生率、避孕效果,以及术后并发症等临床指标均优于对照组。结论为行人工流产手术患者术后立即服用短效避孕药妈富隆,能够取得较好临床效果。%Objective To study the clinical effect of explore artificial abortion for patients with oral immediately after desogestrel acetylene estrone(ma fulong). MethodsFrom October 2013 to December 2015 in our hospital obstetrics abortion 220 patients as the research object,the patients were randomly divided into study group and control group,110 cases in each group. The study of oral antibiotics immediately after artificial abortion group with desogestrel acetylene estrone,and motherwort granule,control group patients only taking antibiotics and motherwort granule,clinical curative effect of two groups were compared.Results The patients in the study group the amount of vaginal bleeding,vaginal bleeding duration,menstrual cycle recovery,complication rate,contraceptive effect,and postoperative complications and other clinical indicators are better than the control group. Conclusion For patients with artificial abortion operation immediately after taking short acting contraceptives to desogestrel acetylene estrone. Enough to achieve good clinical results.

  8. Ploidy Variation in Hybrids from Interploid 3x X 2x Crosses in Musa

    Directory of Open Access Journals (Sweden)

    Osuji, JO.

    1997-01-01

    Full Text Available Hybrids were obtained after in vitro germination of embryos from interploid crosses between triploid 'French' plantain cultivars (Musa spp. AAB group 'Ntanga 2' and 'Bobby Tannap' with diploid banana (Ivlusa acuminata subsp. burmannicoidesj 'Calcutta 4'. Cross-pollinated bunches were harvested at full maturity and ripened with acetylene in a room for 4 days. Seeds were extracted from peeled ripe fruits by squashing. Embryos from the seeds were excised aseptically after 2 days and germinated in vitro. Seedlings were subsequently planted in early evaluation trials after acclimatising in the greenhouse. Chromosome counts were carried out on root tips of mature and maiden suckers to determine ploidy levels using a modified squashing technique. Counts showed that two of the hybrids were aneuploids (trisomies with somatic chromosome number of 2n = 2x + 1 = 23, one hybrid was diploid while the other two were tetraploids. Tetraploids are the most promising hybrids for the genetic improvement of plantains. Diploids are valuable material for further improvement of the plantain genome at this ploidy level. Trisomies provide means for further characterisation of the Musa genome and physical gene mapping in plantain and banana.

  9. Facile, soot free approach toward synthesis of carbon nanoropes via chemical vapor deposition of acetylene in the presence of MnFe2O4 coated on stainless steel

    Science.gov (United States)

    Dhand, Vivek; Bharadwaj, S.; Amareshwari, K.; Himabindu, V.; Rhee, Kyong Yop; Park, Soo-Jin; Hui, David

    2015-12-01

    High density, soot free, novel and a facile approach toward synthesis of carbon nanoropes (CNRs) were successfully carried out in a chemical vapor deposition (CVD) process. Manganese ferrite (MnFe2O4) coated on stainless steel foil (SS 316 grade) was used as a catalyst to initiate the growth of CNR. The coated catalyst was introduced into the CVD and the chamber temperature was set at 700 °C later followed with the release of acetylene (50 sccm) and nitrogen (500 sccm) gas, respectively. Total reaction continued until 30 min. No purification or oxidation process of the soot was involved. Analysis reveals the presence of intermingled CNRs with semi crystalline nature of the sample. The elemental analysis confirms the presence of manganese and iron whereas Raman spectrum shows the characteristic narrow G and D bands. The sample displays a super-paramagnetic behavior and is thermally stable up to 500-550 °C presenting a strong exothermic reaction.

  10. 乙炔法聚氯乙烯生产减少汞排放的“最佳环境实践”%Mercury Emission Control in Acetylene-route PVC Production

    Institute of Scientific and Technical Information of China (English)

    于建国

    2011-01-01

    “最佳环境实践”是国际上普遍推行的旨在减少和控制目标领域和场所环境污染与健康危害的综合管理手段。文中论述了我国乙炔法聚氯乙烯生产中汞使用和排放的“最佳环境实践”,并提出了建议。%World mercury annual consumption is 1,6 kt. China annual mercury consumption in acetylene-route PVC production is 67 ton. Mercury pollution in China is considered to be one of the focal points worldwide. The negotiation committee has been established amon

  11. 气相色谱法测定液氧中乙炔含量的试验研究%Experimental Study on the Measurement of the Content of Acetylene in Liquid Oxygen with Gas Chromatographic Method

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    The space division workshop of oxygen generation plant in a company adopts gas chromatographic method to determine the content of acetylene in liquid oxygen instead of the original visual colorimetric method, and through the comparison of the experimental data, the accuracy of gas chromatographic method analysis is raised substantially, which guarantees safety in production.%  某公司制氧厂空分车间原来采用目视比色法测定液氧中乙炔的含量,存在工艺复杂,消耗试剂多,误差大等缺点。采用气相色谱法代替原来的目视比色法,经试验数据对比,气相色谱法分析准确度大幅度提高,有效的保障了安全生产。

  12. Role of the reaction intermediates in determining PHIP (parahydrogen induced polarization) effect in the hydrogenation of acetylene dicarboxylic acid with the complex [Rh (dppb)]{sup +} (dppb: 1,4-bis(diphenylphosphino)butane)

    Energy Technology Data Exchange (ETDEWEB)

    Reineri, F.; Aime, S. [Department of Molecular Biotechnologies and Health Sciences, University of Torino, Via Nizza 52, 10123 Torino (Italy); Gobetto, R.; Nervi, C. [Department of Chemistry, University of Torino, via P. Giuria 7, 10125 Torino (Italy)

    2014-03-07

    This study deals with the parahydrogenation of the symmetric substrate acetylene dicarboxylic acid catalyzed by a Rh(I) complex bearing the chelating diphosphine dppb (1,4-bis(diphenylphosphino)butane). The two magnetically equivalent protons of the product yield a hyperpolarized emission signal in the {sup 1}H-NMR spectrum. Their polarization intensity varies upon changing the reaction solvent from methanol to acetone. A detailed analysis of the hydrogenation pathway is carried out by means of density functional theory calculations to assess the structure of hydrogenation intermediates and their stability in the two solvents. The observed polarization effects have been accounted on the basis of the obtained structures. Insights into the lifetime of a short-lived reaction intermediate are also obtained.

  13. Cross Shear Roll Bonding

    DEFF Research Database (Denmark)

    Bay, Niels; Bjerregaard, Henrik; Petersen, Søren. B;

    1994-01-01

    The present paper describes an investigation of roll bonding an AlZn alloy to mild steel. Application of cross shear roll bonding, where the two equal sized rolls run with different peripheral speed, is shown to give better bond strength than conventional roll bonding. Improvements of up to 20......-23% in bond strength are found and full bond strength is obtained at a reduction of 50% whereas 65% is required in case of conventional roll bonding. Pseudo cross shear roll bonding, where the cross shear effect is obtained by running two equal sized rolls with different speed, gives the same results....

  14. Peut-on envisager le remplacement de l'éthylène par l'acétylène à moyen terme ? Can the Substitution of Ethylene by Acetylene Be Imagined in the Medium Term?

    Directory of Open Access Journals (Sweden)

    Lefebvre G.

    2006-11-01

    Full Text Available L'accroissement considérable depuis 1973 du coût des énergies fossiles, notamment du pétrole, a fortement contribué au renchérissement du prix de l'éthylène alors que parallèlement l'acétylène fabriqué au départ de carbure de calcium ou par arc électrique pouvait espérer bénéficier d'un coût relatif plus faible de l'énergie électrique d'origine nucléaire. II ressort de la présente étude que malgré les hypothèses favorables suivantes : - taux de croissance moyen du prix du pétrole à monnaie constante 1982 de 7 % par an, - augmentation de celui du charbon limitée à 3 % par an, - énergie électrique disponible en permanence à 5 et 10 c/kWh, - capacité unitaire de production d'acétylène de l'ordre de 300 000 t/an comparable à celle de l'éthylène, il apparaît impossible que l'acétylène puisse concurrencer l'éthylène avant l'an 2000. Seul le chlorure de vinyle pourrait être fabriqué à partir d'acétylène favorisé par un important facteur d'échelle, à condition que l'électricité puisse être alimentée en permanence à 0,10 F le kWh. Cette constatation ne tient pas compte de la remise en cause des procédés pétrochimiques actuels d'obtention des intermédiaires de seconde génération dont la fabrication à partir d'acétylène nécessiterait la création d'installations de conception entièrement différente. Alors qu'en 1975 les procédés à l'arc électrique de production d'acétylène à partir de naphta apparaissaient plus économiques que la voie carbure de calcium, on constate actuellement une situation inverse, consécutive aux augmentations de prix du pétrole qui ont suivi. The considerable increase in the cost of fossil energy sources since 1973, and especially that of oil, has greatly helped drive up the price of ethylene, whereas at the same time acetylene manufactured initially from calcium carbide or by electric arc could have hoped to profit from the relative low price of electric

  15. Cross-Country Skiing.

    Science.gov (United States)

    Arnold, Guy E.

    1980-01-01

    The cross-country ski program offered at Clarkson College in New York is described, including a brief outline of the course, necessary equipment, and suggestions for developing a similar course at other campuses. (JMF)

  16. Floodplain Cross Section Lines

    Data.gov (United States)

    Department of Homeland Security — This table is required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally any FIRM...

  17. HARP MHI- Cross Seamount

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PIFSC and Scripps Institution of Oceanography (SIO) conducted passive acoustic monitoring for cetaceans at Cross Seamount in 2005 and 2006 using a High-Frequency...

  18. Triple crossing numbers of graphs

    OpenAIRE

    Tanaka, Hiroyuki; Teragaito, Masakazu

    2010-01-01

    We introduce the triple crossing number, a variation of crossing number, of a graph, which is the minimal number of crossing points in all drawings with only triple crossings of the graph. It is defined to be zero for a planar graph, and to be infinite unless a graph admits a drawing with only triple crossings. In this paper, we determine the triple crossing numbers for all complete multipartite graphs including all complete graphs.

  19. Cross cultural training

    Institute of Scientific and Technical Information of China (English)

    王容

    2014-01-01

    Under the background of economic globalization, the globalization of human resources management determines the success of enterprise success or failure, in a sense, human resource is the first resource of the enterprise. Cross-cultural training is the core problems in global human resource management, it can let employees quickly familiar with the company's business and job content, understand the enterprise culture and core idea, to play a huge role in promoting enterprise development. Therefore, strengthen enterprise staff training, improve the comprehensive quality of enterprise personnel has become the urgent problems now in the process of enterprise development. Articles in samsung electronics of South Korea, for example, introduces the samsung especial y cross-cultural training content, training method and training effect. And analysis of cross-cultural training impact in the global business team and establish business relationship.

  20. Cross-Country Trek

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    On August 8, 1998, Wu Qi and Yu Yan arrived at Beijing, the destination of a journey that had taken them more than three years. In travelling across 28 provinces, autonomous regions and municipalities, by foot, bus and train, these two young women from Guangzhou had covered a distance of 120,000 kJlometers, the first continuous cross-country journey accomplished by women. On the eve of International Women’s Day (March 8th) of 1995, Wu Qi and Yu Yan quit their jobs and started out on their cross-country

  1. Pullback and pushout crossed polymodules

    Indian Academy of Sciences (India)

    Murat Alp; Bijan Davvaz

    2015-02-01

    In this paper, we introduce the concept of pullback and pushout crossed polymodules and we describe the construction of pullback and pushout crossed polymodules. In particular, by using the notion of fundamental relation, we obtain a crossed module from a pullback crossed polymodule.

  2. Cross-Cultural Leadership

    Directory of Open Access Journals (Sweden)

    Inga Minelgaite Snaebjornsson

    2015-05-01

    Full Text Available Ongoing low participation of women in global leadership calls for more research in this field. In this article, we set out to include gendered expectations toward leader behavior as part of cross-cultural leadership theory. Building on an existing body of research, we focus on propositions about the effects of gendered expectations on the leader, from the followers’ standpoint. The consideration of gendered effects from the follower standpoint is an under-researched area in leadership literature, and it is even more rarely to be found in empirical data. In every culture, there are certain expectations toward leaders of the two genders that influence their behavior. In this article, we will attempt to answer the following question: How does perceived leader behavior and gendered behavior relate to national culture and actual leader behavior? We present a conceptual model that seeks to incorporate gendered expectations into cross-cultural leadership as an answer. Moreover, we provide a conceptual guideline toward operationalization of the model. The model includes the potential of dissonance between male expectations as a dominating leadership role and female leadership. This might serve as an explanation as to why in some cases women are not seen as successful as men when they adopt a masculine leadership style. The article seeks to advance cross-cultural leadership theory by focusing on expected gendered leadership behavior. Our ideas and model could eventually contribute to the advancement of leadership theory, as well as contributing to gender studies, cross-cultural leadership, and business communication.

  3. Cross-Cultural Psychology.

    Science.gov (United States)

    Triandis, Harry C.; Brislin, Richard W.

    Cross-Cultural psychology refers to the collective efforts of researchers who work among people who live in different societies, with different languages and different forms of government. There are a number of benefits to the study of human behavior which can be accrued by carrying out research in various cultures, largely concerned with better…

  4. Cross Disciplinary Biometric Systems

    CERN Document Server

    Liu, Chengjun

    2012-01-01

    Cross disciplinary biometric systems help boost the performance of the conventional systems. Not only is the recognition accuracy significantly improved, but also the robustness of the systems is greatly enhanced in the challenging environments, such as varying illumination conditions. By leveraging the cross disciplinary technologies, face recognition systems, fingerprint recognition systems, iris recognition systems, as well as image search systems all benefit in terms of recognition performance.  Take face recognition for an example, which is not only the most natural way human beings recognize the identity of each other, but also the least privacy-intrusive means because people show their face publicly every day. Face recognition systems display superb performance when they capitalize on the innovative ideas across color science, mathematics, and computer science (e.g., pattern recognition, machine learning, and image processing). The novel ideas lead to the development of new color models and effective ...

  5. Cross-commodity hedges

    International Nuclear Information System (INIS)

    Energy risk management is the principal topic of this paper. Four major subjects are examined: cross-commodity trading objectives (reduce the risk of an underlying exposure in another commodity); portfolio risk reduction (an Alberta power distributor exposed to high pool prices could protect against high pool prices through a fixed price purchase of Alberta natural gas); tailoring pricing to customer needs (sell power to the gas producer indexed to the price of gas); and (4) reducing insurance costs (rather than purchasing downside protection (puts) individually against oil and gas prices, a producer could purchase a basket option). Since the key issue in cross-commodity transactions is the estimation of correlation, it is important to be prepared to alter correlation assumptions. 1 tab., 2 figs

  6. Cross-cultural advertising

    OpenAIRE

    Пурчельянова, Н. Ю.

    2011-01-01

    The essence of successful advertising is to convince people that a product is meant for them. By purchasing it, they will receive some benefit (lifestyle, status, convenience, etc.). However, when an advertising campaign is taken abroad different values as to what enhances status or gives convenience exist. These differences make the original advertising campaign defunct. It is therefore critical to any cross cultural advertising campaign that an understanding of a particular culture is acqui...

  7. Cross-cultural Leadership

    OpenAIRE

    Oana Simona Hudea

    2014-01-01

    The present paper is meant to outline the positive effects that diversity may have on any organisation, subject to the condition that the said diversity be appropriately managed. As the leader is a person who, by power of example, makes other people adopting a similar attitude, the actions of the same oriented towards the fructification of the advantages of a cross-cultural environment, which are depicted in this study, are not only directly, but also indirectly, by synergy, impacting, in a p...

  8. Partial and unified crossed products are weak crossed products

    CERN Document Server

    Vilaboa, J M Fernández; Raposo, A B Rodríguez

    2011-01-01

    In [J.M. Fern\\'andez Vilaboa, R. Gonz\\'alez Rodr\\'iguez and A.B. Rodr\\'iguez Raposo: Preunits and weak crossed products. J. of Pure Appl. Algebra 213, 2244-2261 (2009)] the notion of a weak crossed product of an algebra by an object, both living in a monoidal category was presented. Unified crossed products defined in [A. Agore, G. Militaru: Extending structures II: The quantum version. arXiv:1011.2174v3 (2011)] and partial crossed products defined in [M. Muniz S. Alves, E. Batista, M. Dokuchaev, A. Paques: Twisted partial actions of Hopf algebras. preprint (2011)] are crossed product structures defined for a Hopf algebra and another object. In this paper we prove that unified crossed products and partial crossed products are particular instances of weak crossed products.

  9. The role of isovalency in the reactions of the cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H) radicals with unsaturated hydrocarbons acetylene (C2H2) and ethylene (C2H4).

    Science.gov (United States)

    Parker, D S N; Mebel, A M; Kaiser, R I

    2014-04-21

    The classification of chemical reactions based on shared characteristics is at the heart of the chemical sciences, and is well exemplified by Langmuir's concept of isovalency, in which 'two molecular entities with the same number of valence electrons have similar chemistries'. Within this account we further investigate the ramifications of the isovalency of four radicals with the same X(2)Σ(+) electronic structure - cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H), and their reactions with simple prototype hydrocarbons acetylene (C2H2) and ethylene (C2H4). The fact that these four reactants own the same X(2)Σ(+) electronic ground state should dictate the outcome of their reactions with prototypical hydrocarbons holding a carbon-carbon triple and double bond. However, we find that other factors come into play, namely, atomic radii, bonding orbital overlaps, and preferential location of the radical site. These doublet radical reactions with simple hydrocarbons play significant roles in extreme environments such as the interstellar medium and planetary atmospheres (CN, SiN and C2H), and combustion flames (C2H, BO). PMID:24418936

  10. Diffractive and rising cross sections

    International Nuclear Information System (INIS)

    The energy dependence of the diffractive component of the proton-proton cross section is discussed and its contribution to the rise of the total cross section at high energies is examined. 17 refs., 9 figs

  11. On partitions avoiding right crossings

    OpenAIRE

    Yan, Sherry H. F.; Xu, Yuexiao

    2011-01-01

    Recently, Chen et al. derived the generating function for partitions avoiding right nestings and posed the problem of finding the generating function for partitions avoiding right crossings. In this paper, we derive the generating function for partitions avoiding right crossings via an intermediate structure of partial matchings avoiding 2-right crossings and right nestings. We show that there is a bijection between partial matchings avoiding 2-right crossing and right nestings and partitions...

  12. Safe lighting of pedestrian crossings

    OpenAIRE

    Bláha, Zdeněk; Sokanský, Karel; Novák, Tomáš

    2015-01-01

    This paper solves the lighting of pedestrian crossings. This type of lighting helps to improve the safety of pedestrians in this conflict area (means a pedestrian crossing). The research was drawn on the basis of measurements of 87 pedestrian crossings in district Ostrava because the regularities can be better understood. Pedestrian crossings were evaluated on the basis of luminance ratio and statistical data of accident rate. This paper also solves the reflectance of clothes which is also im...

  13. German cross-cultural psychology

    OpenAIRE

    Trommsdorff, Gisela

    1986-01-01

    The present study deals with German-language cross-cultural research in different fields of psychology which attempts to achieve one Or more goals of cross-cultural psychology. First, methodological problems are discussed, followed by a selective presentation of cross-cultural research in personality, clinical, ethological, developmental, and social psychology. The theoretical and methodological advancement of these studies is investigated with respect to four approaches - universals in cross...

  14. [Fast neutron cross section measurements

    International Nuclear Information System (INIS)

    This paper discusses the following topics: 14 MeV pulsed neutron facility; detection and measurement system; 238U capture cross sections at 23 and 964 keV using photon neutron sources; capture cross sections of Au-197 at 23 and 964 keV; and yttrium nuclear cross section measurement

  15. 'Crossing a Bare Common'

    DEFF Research Database (Denmark)

    Balle, Søren Hattesen

    2006-01-01

    and thinking about the sublime. To put it very simply, this means to present a version of the sublime in which transcendence is transposed ‘into a naturalistic key’ – to use Thomas Weiskel’s apt phrase. Admittedly, this is hardly a new, nor a very original way of situating Emerson’s sublime. Here I follow...... rhetoric of crossing – notably through the figures of hyperbole, chiasmus and metalepsis – represents a kind of double talk, where its assertions of sublimity are made ironically so as to suggest their potentially self-cancelling nature. In this context I shall investigate some of the paratextual...

  16. Cross-cultural Leadership

    Directory of Open Access Journals (Sweden)

    Oana Simona Hudea

    2014-05-01

    Full Text Available The present paper is meant to outline the positive effects that diversity may have on any organisation, subject to the condition that the said diversity be appropriately managed. As the leader is a person who, by power of example, makes other people adopting a similar attitude, the actions of the same oriented towards the fructification of the advantages of a cross-cultural environment, which are depicted in this study, are not only directly, but also indirectly, by synergy, impacting, in a positive way, on the organisation.Innovation, performance, competitive advantage and reputation are just some of the outcomes of finding unity in diversity.

  17. Cosmetic crossings and Seifert matrices

    CERN Document Server

    Balm, Cheryl; Kalfagianni, Efstratia; Powell, Mark

    2011-01-01

    We study cosmetic crossings in knots of genus one and obtain obstructions to such crossings in terms of knot invariants determined by Seifert matrices. In particular, we prove that for genus one knots the Alexander polynomial and the homology of the double cover branching over the knot provide obstructions to cosmetic crossings. As an application we prove the nugatory crossing conjecture for twisted Whitehead doubles of non-cable knots. We also verify the conjecture for several families of pretzel knots and all genus one knots with up to 12 crossings.

  18. Cross border relationships

    DEFF Research Database (Denmark)

    Singla, Rashmi; Sriram, Sujata

    2010-01-01

    in which they were born. These movements also imply human relationships across the borders in different contexts with various cultural, psychological consequences. Relationships of members of migrant groups with each other, and also with the host community have important implications on the health and well......-being of not just the migrant population, but also the host communities. These relationships represent the microcosm of societal and cultural integration and cohesion at the broader levels. Studies of how and how well migrants, especially youth handle migration indicate transformations in paradigms as both...... acculturative stress and developmental possibilities are realities experienced in the search of new worlds and new opportunities. The symposia will include such changes from Denmark, India, UK and the USA, covering theoretical, methodological issues including the ethical aspects. Themes involved in crossing...

  19. Group cross sections calculations

    International Nuclear Information System (INIS)

    Just a few methods have been developped to compute multigroup cross-sections from ENDF data. We have developped an original method in order to get accuracy and to reduce the number of discretization points in the same time; this is why we have tried to use polynomial integration. In this paper, we describe this method: in the first part, we recall some physical hypothesis generally used to solve the linear Boltzmann equation: that is the frame in which the numerical method has been developped. Polynomial methods are really powerfull only if discretization points are suitably chosen. This choice is explained in the next part of this paper. In conclusion, some numerical results are given to illustrate our method

  20. 'Crossing a Bare Common'

    DEFF Research Database (Denmark)

    Balle, Søren Hattesen

    2006-01-01

    and thinking about the sublime. To put it very simply, this means to present a version of the sublime in which transcendence is transposed ‘into a naturalistic key’ – to use Thomas Weiskel’s apt phrase. Admittedly, this is hardly a new, nor a very original way of situating Emerson’s sublime. Here I follow...... on the rhetorical level to accomplish the kind of crossing into transcendence that describes the sublime experience on the thematic level of Emerson’s texts. The second main claim of my paper, however, is to propose that Emerson does not use these tropes in an unreserved apotheosis of the sublime. Though...... and intertextual framing devices used by Emerson in order to question the authority of his own discourse. Among those of most importance will be included ones such as warped allusions to classic sublime texts, the choice of the essay genre in preference to the poetic genre, the use of epigraphs, the use...

  1. Neutrino Cross section Future

    CERN Document Server

    Gollapinni, Sowjanya

    2016-01-01

    The study of neutrino-nucleus interactions has recently received renewed attention due to their importance in interpreting the neutrino oscillation data. Over the past few years, there has been continuous disagreement between neutrino cross section data and predictions due to lack of accurate nuclear models suitable for modern experiments which use heavier nuclear targets. Also, the current short and long-baseline neutrino oscillation experiments focus in the few GeV region where several distinct neutrino processes come into play resulting in complex nuclear effects. Despite recent efforts, more experimental input is needed to improve nuclear models and reduce neutrino interaction systematics which are currently dominating oscillation searches together with neutrino flux uncertainties. A number of new detector concepts with diverse neutrino beams and nuclear targets are currently being developed to provide necessary inputs required for next generation oscillation experiments. This paper summarizes these effor...

  2. Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases

    Science.gov (United States)

    Sosnovsky, Denis V.; Jeschke, Gunnar; Matysik, Jörg; Vieth, Hans-Martin; Ivanov, Konstantin L.

    2016-04-01

    Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign

  3. Darling-Dennison resonance and Coriolis coupling in the bending overtones of the A 1A(u) state of acetylene, C2H2.

    Science.gov (United States)

    Merer, Anthony J; Yamakita, Nami; Tsuchiya, Soji; Steeves, Adam H; Bechtel, Hans A; Field, Robert W

    2008-08-01

    Rotational analyses have been carried out for the overtones of the nu(4) (torsion) and nu(6) (in-plane cis-bend) vibrations of the A (1)A(u) state of C(2)H(2). The v(4)+v(6)=2 vibrational polyad was observed in high-sensitivity one-photon laser-induced fluorescence spectra and the v(4)+v(6)=3 polyad was observed in IR-UV double resonance spectra via the ground state nu(3) (Sigma(+) (u)) and nu(3)+nu(4) (Pi(u)) vibrational levels. The structures of these polyads are dominated by the effects of vibrational angular momentum: Vibrational levels of different symmetry interact via strong a-and b-axis Coriolis coupling, while levels of the same symmetry interact via Darling-Dennison resonance, where the interaction parameter has the exceptionally large value K(4466)=-51.68 cm(-1). The K-structures of the polyads bear almost no resemblance to the normal asymmetric top patterns, and many local avoided crossings occur between close-lying levels with nominal K-values differing by one or more units. Least squares analysis shows that the coupling parameters change only slightly with vibrational excitation, which has allowed successful predictions of the structures of the higher polyads: A number of weak bands from the v(4)+v(6)=4 and 5 polyads have been identified unambiguously. The state discovered by Scherer et al. [J. Chem. Phys. 85, 6315 (1986)], which appears to interact with the K=1 levels of the 3(3) vibrational state at low J, is identified as the second highest of the five K=1 members of the v(4)+v(6)=4 polyad. After allowing for the Darling-Dennison resonance, the zero-order bending structure can be represented by omega(4)=764.71, omega(6)=772.50, x(44)=0.19, x(66)=-4.23, and x(46)=11.39 cm(-1). The parameters x(46) and K(4466) are both sums of contributions from the vibrational angular momentum and from the anharmonic force field. For x(46) these contributions are 14.12 and -2.73 cm(-1), respectively, while the corresponding values for K(4466) are -28.24 and -23

  4. Application of the 15N gas-flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Science.gov (United States)

    Sgouridis, Fotis; Stott, Andrew; Ullah, Sami

    2016-03-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilized agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in-house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps and a copper-based reduction furnace, and allows the analysis of small gas injection volumes (4 µL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Preconcentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N gas-flux method was adapted for application in natural and semi-natural land use types (peatlands, forests, and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. The minimum detectable flux rates were 4 µg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. Total denitrification rates measured by the acetylene inhibition technique in the same land use types correlated (r = 0.58) with the denitrification rates measured under the 15N gas-flux method, but were underestimated by a factor of 4, and this was partially attributed to the incomplete inhibition of N2O reduction to N2, under a relatively high soil moisture content, and/or the catalytic NO decomposition in the presence of acetylene. Even though relatively robust for in situ denitrification measurements, methodological

  5. Cross-tools and cross-media effects

    NARCIS (Netherlands)

    H. Voorveld

    2013-01-01

    Effects of persuasive messages depend on the content of the message itself and on the media or tools that deliver the persuasive messages. Nowadays almost all campaigns make use of multiple media or multiple promotional tools. Therefore, it is important to study so-called cross-media (or cross-tools

  6. The total charm cross section

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R

    2007-09-14

    We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that the uncertainty on the total charm cross section is difficult to quantify.

  7. Cross-Country Skiing Today.

    Science.gov (United States)

    Caldwell, John

    This book presents changes in cross country skiing which have taken place in the last several years and is directed toward both beginning and seasoned tour skiers. Discussed are the following topics: (1) the cross-country revolution (new fiberglass skis); (2) equipment (how to choose from the new waxless touring skis); (3) care of equipment; (4)…

  8. The safety of pedestrian crossing

    NARCIS (Netherlands)

    Goede, M. de; Groenewoud, C.; Horst, A.R.A. van der

    2010-01-01

    More than half of all severe traffic accidents in which pedestrians or cyclists are involved, occur during road crossing. In this chapter insights, based on previous studies and literature, concerning requirements for safe and comfortable crossing facilities are discussed. In order to develop notion

  9. XCOM: Photon Cross Sections Database

    Science.gov (United States)

    SRD 8 XCOM: Photon Cross Sections Database (Web, free access)   A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z energies from 1 keV to 100 GeV.

  10. On crossed product of algebras

    OpenAIRE

    Borowiec, A.; Marcinek, W.

    2000-01-01

    The concept of a crossed tensor product of algebras is studied from a few points of views. Some related constructions are considered. Crossed enveloping algebras and their representations are discussed. Applications to the noncommutative geometry and particle systems with generalized statistics are indicated.

  11. Internet and Cross Media Productions

    DEFF Research Database (Denmark)

    Petersen, Anja Bechmann

    2006-01-01

    , the Internet continues to play a minor role when compared to older media. The content of the cross media concepts and organizations' history are crucial elements in deciding the priority and use of platforms. Methodologically, the article approaches cross media and the roles of the Internet on a micro......Convergence is one of the hot topics in Internet studies. Recently, however, media organizations have turned their focus to cross media communication. Media organizations are interested in optimizing communication across platforms such as TV, radio, websites, mobile telephones and newspapers....... The aim of this article is to examine the roles of the Internet when emphasis is put on cross media rather than convergence. This article proposes not one unidirectional convergent tendency but manifold roles of the Internet in cross media communication. Inside the media organizations, however...

  12. Cross helicity and related dynamo

    CERN Document Server

    Yokoi, Nobumitsu

    2013-01-01

    The turbulent cross helicity is directly related to the coupling coefficients for the mean vorticity in the electromotive force and for the mean magnetic-field strain in the Reynolds stress tensor. This suggests that the cross-helicity effects are important in the cases where global inhomogeneous flow and magnetic-field structures are present. Since such large-scale structures are ubiquitous in geo/astrophysical phenomena, the cross-helicity effect is expected to play an important role in geo/astrophysical flows. In the presence of turbulent cross helicity, the mean vortical motion contributes to the turbulent electromotive force. Magnetic-field generation due to this effect is called the cross-helicity dynamo. Several features of the cross-helicity dynamo are introduced. Unlike the case in the helicity or $\\alpha$ effect, where ${\\bf{J}}$ is aligned with ${\\bf{B}}$ in the turbulent electromotive force, we in general have a finite mean-field Lorentz force ${\\bf{J}} \\times {\\bf{B}}$ in the cross-helicity dynam...

  13. Synthesis of nano-carbon materials by decomposing acetylene using iron supported on sodium chloride as catalyst%NaCl担载Fe催化裂解乙炔制备纳米碳材料

    Institute of Scientific and Technical Information of China (English)

    王存景; 王艳博; 陈改荣

    2011-01-01

    Nano-carbon materials were synthesized by the catalytic decomposition of acetylene at 400 ℃ and 420℃ in a chemical vapor deposition process using iron supported on sodium chloride as catalyst Hie catalyst was examined by X-ray diffraction,scanning electron microscopy and energy dispersive spectroscopy. The results show that the active composition iron was dispersed into nanoparticles with diameters in the range 10-40 nm on the surface of NaCl support successfully. The products were examined by scanning electron microscopy and high resolution transmission electron microscopy. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained when the reaction temperature was 400℃ and there were no carbon nanotubes in the product These onion-like fullerenes are composed of concentric graphene layers with an interlayer distance of 0. 348 nm between the layers. When the reaction temperature was 420℃ , carbon nanotubes with a structure of rope were obtained and the graphitization degree of these carbon nanotubes was not high due to the low reaction temperature.%以水溶性NaCl担载Fe作催化剂,于400℃和420C下化学气相沉积法催化裂解乙炔进行了反应.通过X射线衍射仪、扫描电子显微镜和能谱分析仪对催化剂进行了表征,表征结果显示:活性组分Fe被分散成了粒径在10~40nm之间的纳米颗粒;通过扫描电子显微镜和高分辨透射电镜对产物进行了表征,表征结果显示:当裂解温度为400℃时,主要产物为直径在20~50 nm之间,基本具有清晰同心石墨壳层结构的内包铁NOLFs,同心石墨壳层的层间距约为0.348nm,产物中没有碳纳米管出现;当裂解温度为420℃时,主要产物为直径在10 ~40 nm之间结构呈绳结状的碳纳米管,其石墨壳层不是十分规整,石墨化程度较低.

  14. Adverse selection without single crossing

    DEFF Research Database (Denmark)

    Schottmüller, Christoph

    2015-01-01

    The single-crossing assumption simplifies the analysis of screening models as local incentive compatibility becomes sufficient for global incentive compatibility. If single crossing is violated, global incentive compatibility constraints have to be taken into account. This paper studies monotone...... solutions in a screening model that allows a one-time violation of single crossing. The results show that local and non-local incentive constraints distort the solution in opposite directions. Therefore, the optimal decision might involve distortions above as well as below the first-best decision...

  15. Opas CrossFit -harjoitteluun

    OpenAIRE

    Knaapi, Matti

    2014-01-01

    CrossFit on laji, joka pyrkii edistämään terveyttä ja kuntoa. CrossFit saleja löytyy mailmalta yli 10 000 kappaletta. CrossFit -harjoittelussa pyritään parantamaan ihmisen kuntoa mahdollisimman laajalla skaalalla kehittämällä mm. voimaa, kestävyyttä, tarkkuutta, tasapainoa ja eri aineenvaihduntareittejä samanaikaisesti. Terveyden ja kunnon kehittämiseen kuuluu kuntoilun lisäksi myös muita osa-alueita. Ruokavalio ja kehonhuolto ovat tärkeitä osa-alueita hyvän kunnon saavuttamiseksi. Ruokav...

  16. Crossing borders via mental bridges

    DEFF Research Database (Denmark)

    Keil, Dirk

    influence coopera- tion, coordination and collaboration in administrative cross-border networks. In this connection the project asks after the perception of regional integration seen from the different national backgrounds. The research concentrates on the group of decision makers within the field of public......The project studies cross-border regional integration in Europe drawing on the example of the emerging Danish-German Femern Belt Region. It focuses on cross-border networking within public administration as part of regional integra- tion. My central question is how national-cultural differences...

  17. Cross-National Yardstick Comparisons

    DEFF Research Database (Denmark)

    Hansen, Kasper Møller; Olsen, Asmus Leth; Bech, Michael

    2015-01-01

    performance comparisons—even when accounting for classic national sociotropic and egotropic items. Specifically, voters respond strongly to how the prospective wealth of Denmark evolves relative to the neighboring Sweden. Interestingly, voters are more negative in their response to cross-national losses......Comparing performance between countries is both a theoretically and intuitively useful yardstick for voters. Cross-national comparisons provide voters with heuristics that are less cognitively demanding, less ambiguous, and less uncertain than solely national, absolute performance measurements. We...... test this proposition using a unique, choice experiment embedded in the 2011 Danish National Election Study. This design allows to contrast cross-national comparisons with more traditional national sociotropic and egotropic concerns. The findings suggest that voters are strongly influenced by cross-national...

  18. Canada and Mexico Border Crossings

    Data.gov (United States)

    Department of Homeland Security — Border Crossing Ports are points of entry for land modes along the U.S. - Canadian and U.S.- Mexcian borders. The ports of entry are located in 15 states along the...

  19. Major Breakthrough in Pipeline Crossing

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    @@ Based on 10 years of concentrated study, the scientific and technical personnel of No. 2 oil field Construction Company of Liaohe Oil Field succeeded its river-crossing technique for curvilinear push pipe on March 10,1997.

  20. The definition of cross polarization

    DEFF Research Database (Denmark)

    Ludwig, Arthur

    1973-01-01

    There are at least three different definitions of cross polarization used in the literature. The alternative definitions are discussed with respect to several applications, and the definition which corresponds to one standard measurement practice is proposed as the best choice....

  1. Cross-correlation laser scattering.

    OpenAIRE

    Kam, Z; Rigler, R

    1982-01-01

    Cross-correlation between two detectors was applied to analyze laser light-scattering fluctuations. Laser scattering from random concentration fluctuations is spatially coherent over small angular areas that are inversely proportional in size to the dimension of the scattering volume. By cross-correlating scattering intensity fluctuations in different angles, the correlation due to relaxation of concentration fluctuations is practically eliminated, and correlations reflecting changes in the s...

  2. The total charm cross section

    OpenAIRE

    R. Vogt

    2007-01-01

    We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that due to the small charm quark mass, which amplifies the effect of the other parameters in the calculation, the uncertainty on the total charm cross section is difficult to quantify.

  3. Entropy, Duality and Cross Diffusion

    OpenAIRE

    Desvillettes, Laurent; Lepoutre, Thomas; Moussa, Ayman

    2013-01-01

    This paper is devoted to the use of the entropy and duality methods for the existence theory of reaction-cross diffusion systems consisting of two equations, in any dimension of space. Those systems appear in population dynamics when the diffusion rates of individuals of two species depend on the concentration of individuals of the same species (self-diffusion), or of the other species (cross diffusion).

  4. Syntheses and studies of acetylenic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Yiwei, Ding

    1994-03-03

    Based on new diiodo aryl compounds a series of novel soluble polymers, poly(2,5-dialkoxy-1,4-phenyleneethynylene)s (PPE polymers) were synthesized using palladium-catalysis. The molecular weights (MW) range from 8,000 to 40,000. Properties such as absorption, fluorescence, and conductivity were studied. A PPE polymer with butoxy side chain exhibits a weak electrical conductivity ({sigma} = 10{sup {minus}3} S/cm) after doping with AsF{sub 5}. Absorption spectra in THF solution at room temperature (RT) show a maximum at 440 nm. However, absorption spectra of PPE polymers in the film state at (RT) show a maximum at 480 nm. PPE polymer-based light emitting diode (LED) devices have been prepared; greenish light from these LED devices can be observed. Poly(ethynylene-p-arylene-ethynylene-silylene)s were synthesized through the same palladium-catalyzed polymerization; MWs are between 6,000 and 82,000. Absorption and fluorescence were studied. Some of these polymers exhibit thermotropic liquid crystalline properties. In addition, nonlinear optical properties were briefly examined. Poly(silylene-ethynylene) homopolymers as well as alternating copolymers were synthesized through a novel palladium-catalyzed polymerization; MWs range from 56 {times} 10{sup 3} to 5.3 {times} 10{sup 3}. Thermal stability of these was also investigated; char yields range from 56 to 83%. One of these polymers exhibits thermotropic liquid crystalline properties.

  5. Cross-cultural communication and global economy

    OpenAIRE

    Krutskikh A. V.

    2011-01-01

    The article gives a review of the basic issues related to cross-cultural communication. The author focuses on the origin of cross-cultural diversity and analyses modern approaches to building cross-cultural competence.

  6. Triple Crossing Numb ers of Graphs

    Institute of Scientific and Technical Information of China (English)

    Tanaka Hiroyuki; Teragaito Masakazu

    2016-01-01

    We introduce the triple crossing number, a variation of the crossing number, of a graph, which is the minimal number of crossing points in all drawings of the graph with only triple crossings. It is defined to be zero for planar graphs, and to be infinite for non-planar graphs which do not admit a drawing with only triple crossings. In this paper, we determine the triple crossing numbers for all complete multipartite graphs which include all complete graphs.

  7. Cross-cultural organizational behavior.

    Science.gov (United States)

    Gelfand, Michele J; Erez, Miriam; Aycan, Zeynep

    2007-01-01

    This article reviews research on cross-cultural organizational behavior (OB). After a brief review of the history of cross-cultural OB, we review research on work motivation, or the factors that energize, direct, and sustain effort across cultures. We next consider the relationship between the individual and the organization, and review research on culture and organizational commitment, psychological contracts, justice, citizenship behavior, and person-environment fit. Thereafter, we consider how individuals manage their interdependence in organizations, and review research on culture and negotiation and disputing, teams, and leadership, followed by research on managing across borders and expatriation. The review shows that developmentally, cross-cultural research in OB is coming of age. Yet we also highlight critical challenges for future research, including moving beyond values to explain cultural differences, attending to levels of analysis issues, incorporating social and organizational context factors into cross-cultural research, taking indigenous perspectives seriously, and moving beyond intracultural comparisons to understand the dynamics of cross-cultural interfaces. PMID:17044797

  8. CHALLENGES IN CROSS CULTURAL ADVERTISING

    Directory of Open Access Journals (Sweden)

    Yuni Retnowati

    2015-10-01

    Full Text Available At first, marketing practitioners and academics consider standardized approaches to marketing and advertising strategies in globalization, and then some studies proved that the standardization of advertising across culture is not valid. Therefore, cross cultural advertising takes local culture into account when conveying messages in advertisements. Cross cultural understanding is very important in order to produce successful localized advertising that would reflect the cultural values and norms of intended audience. Challenge in cross cultural advertising is the problem of communicating to people of diverse cultural background. Cross cultural solutions are applied in areas such as language, communication style, images and cultural values. Cross cultural advertising is simply about using common sense and analyzing how the different elements of an advertising campaign are impacted by culture and modifying them to best speak to the target audience. Other challenges are determining between standardization and adaptation of cultural values content of advertising when facing different people from diverse cultures. In academic side, the challenge is preparing students to design advertisements that communicate effectively to diverse cultures.

  9. Regenerator cross arm seal assembly

    Science.gov (United States)

    Jackman, Anthony V.

    1988-01-01

    A seal assembly for disposition between a cross arm on a gas turbine engine block and a regenerator disc, the seal assembly including a platform coextensive with the cross arm, a seal and wear layer sealingly and slidingly engaging the regenerator disc, a porous and compliant support layer between the platform and the seal and wear layer porous enough to permit flow of cooling air therethrough and compliant to accommodate relative thermal growth and distortion, a dike between the seal and wear layer and the platform for preventing cross flow through the support layer between engine exhaust and pressurized air passages, and air diversion passages for directing unregenerated pressurized air through the support layer to cool the seal and wear layer and then back into the flow of regenerated pressurized air.

  10. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Science.gov (United States)

    Sgouridis, F.; Ullah, S.; Stott, A.

    2015-08-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Pre-concentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. For our chamber design (volume / surface = 8:1) and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. The N2 flux ranged between 2.4 and 416.6 μg N m-2 h-1, and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N2O flux was on average 20 to 200 times lower than the N2 flux, while the denitrification product ratio (N2O/N2 + N2O) was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique under the same field conditions

  11. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Directory of Open Access Journals (Sweden)

    F. Sgouridis

    2015-08-01

    Full Text Available Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS. The N2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Pre-concentrator (Isoprime Ltd coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume. Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm was better than 0.5 %. The 15N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands by lowering the 15N tracer application rate to 0.04–0.5 kg 15N ha−1. For our chamber design (volume / surface = 8:1 and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m−2 h−1 and 0.2 ng N m−2 h−1 for the N2 and N2O fluxes respectively. The N2 flux ranged between 2.4 and 416.6 μg N m−2 h−1, and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N2O flux was on average 20 to 200 times lower than the N2 flux, while the denitrification product ratio (N2O/N2 + N2O was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique

  12. 39 CFR 259.2 - Red Cross.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Red Cross. 259.2 Section 259.2 Postal Service....2 Red Cross. (a) General. The Postal Service and the Red Cross cooperate to maintain communication... those caused by enemy action. (b) Role of Postal Service. The Postal Service and the Red Cross...

  13. Teaching Cross-Country Skiing.

    Science.gov (United States)

    Nelson, Jonathan E.

    1984-01-01

    Cross-country skiing instruction can be done both inside and outside the gymnasium. This article provides activities to be performed inside to prepare students for skiing. Outside organization techniques and drills are suggested. A list of common errors is given. (DF)

  14. Assessing Cross-Media Impacts

    Science.gov (United States)

    Reiquam, Howard; And Others

    1975-01-01

    Using 1000 MW coal-fired central power stations as an example, the impacts upon other media (land, air, water) are analyzed when controls are imposed on one medium. The development of a methodology for assessing the cross-media impact of specific control technologies or strategies is illustrated. (Author/BT)

  15. Redressing Cross-Dressed Shakespeare

    Science.gov (United States)

    Martin, Thomas L.; Pesta, Duke

    2003-01-01

    Gender critics obsess over the boy actors who played female roles on the Elizabethan stage. But, in their far-fetched interpretation of Shakespearean drama as a spectacle of cross dressing, these new historicists lose sight of a fundamental principle of theater. Thomas Martin and Duke Pesta argue that with their prurient chatter of "the…

  16. A Crossing Method for Quinoa

    Directory of Open Access Journals (Sweden)

    Adam Peterson

    2015-03-01

    Full Text Available As sustainable production of quinoa (Chenopodium quinoa Willd. increases and its geographic range of cultivation expands, quinoa breeding will allow use of the crop’s wide genetic diversity for cultivar improvement and for adaptation to new agroecosystems and climactic regimes. Such breeding work will require a reliable technique for crossing quinoa plants using hand emasculation. The technique described herein focuses on the isolation of small flower clusters produced low on the plant, emasculation of male flowers, and subsequent pairing of the emasculated female parent with a male parent undergoing anthesis. Various traits, such as plant color, seed color, and axil pigmentation can be used to confirm the successful production of F1 plants. The manual hybridization technology provides a significant advantage over pairing plants and relying on chance cross-pollination, and has been successfully used to generate crosses between quinoa cultivars, as well as interspecific crosses between quinoa and Chenopodium berlandieri. This technology will help pave the way for the introduction and sustainable expansion of quinoa on a global scale across a wide range of target environments and diverse farming systems.

  17. Cross-Cultural HRD. Symposium.

    Science.gov (United States)

    2002

    The first of three papers from this symposium on cross-cultural human resource development (HRD), "Determinants of Supply of Technical Training Opportunities for Human Capital Development in Kenya" (Moses Waithanji Ngware, Fredrick Muyia Nafukho) reports findings from interviews of technical training institute department heads in Kenya who…

  18. Terahertz radar cross section measurements

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Heiselberg, Henning; Jepsen, Peter Uhd

    2010-01-01

    We perform angle- and frequency-resolved radar cross section (RCS) measurements on objects at terahertz frequencies. Our RCS measurements are performed on a scale model aircraft of size 5-10 cm in polar and azimuthal configurations, and correspond closely to RCS measurements with conventional radar...

  19. Revolutionizing Cross-sectional Imaging

    CERN Document Server

    Fan, Yifang; Luo, Liangping; Lin, Wentao; Li, Zhiyu; Zhong, Xin; Shi, Changzheng; Newman, Tony; Zhou, Yi; Lv, Changsheng; Fan, Yuzhou

    2014-01-01

    Cross-sectional imaging is so important that, six Nobel Prizes have been awarded to the field of nuclear magnetic resonance alone because it revolutionized clinical diagnosis. The BigBrain project supported by up to 1 billion euro each over a time period of 10 years predicts to "revolutionize our ability to understand internal brain organization" (Evan 2013). If we claim that cross-sectional imaging diagnosis is only semi-quantitative, some may believe because no doctor would ever tell their patient that we can observe the changes of this cross-sectional image next time. If we claim that BigBrain will make no difference in clinical medicine, then few would believe because no doctor would ever tell their patient to scan this part of the image and compare it with that from the BigBrain. If we claim that the BigBrain Project and the Human Brain Project have defects in their key method, one might believe it. But this is true. The key lies in the reconstruction of any cross-sectional image along any axis. Using Ga...

  20. Improved Zero-Crossing Detector

    Science.gov (United States)

    Dick, G. John; Kuhnle, Paul F.

    1992-01-01

    Improved zero-crossing-detector circuit designed for precisely measuring difference between frequencies of two frequency-standard signal sources. Contains low-bandwidth first-stage amplifier and three limiting amplifiers, each "squares" signal bit more. Crosstalk eliminated and jitter reduced to about 10 to the negative 7th power microseconds.

  1. Cross-border innovation cooperation

    DEFF Research Database (Denmark)

    Hjaltadóttir, Rannveig Edda; Makkonen, Teemu; Sørensen, Nils Karl

    2014-01-01

    Finding a suitable partner is paramount for the success of innovation cooperation. Thus, this paper sets out to analyse the determinants of cross-border innovation cooperation in Denmark focusing on partner selection. The aim of the article is to investigate determinants of partner selection taki...

  2. Explorations in bilingual word recognition : cross-modal, cross-sectional, and cross-language effects

    NARCIS (Netherlands)

    Schulpen, B.J.H.

    2003-01-01

    This dissertation explored different aspects of bilingual word recognition. First, bilingual auditory word recognition was examined using interlingual homophones in a cross-modal priming task. Bilinguals were found to activate word candidates in both languages, but were also sensitive to sublexical

  3. Collagen cross linking: Current perspectives

    Directory of Open Access Journals (Sweden)

    Srinivas K Rao

    2013-01-01

    Full Text Available Keratoconus is a common ectatic disorder occurring in more than 1 in 1,000 individuals. The condition typically starts in adolescence and early adulthood. It is a disease with an uncertain cause and its progression is unpredictable, but in extreme cases, vision deteriorates and can require corneal transplant surgery. Corneal collagen cross-linking (CCL with riboflavin (C3R is a recent treatment option that can enhance the rigidity of the cornea and prevent disease progression. Since its inception, the procedure has evolved with newer instrumentation, surgical techniques, and is also now performed for expanded indications other than keratoconus. With increasing experience, newer guidelines regarding optimization of patient selection, the spectrum of complications and their management, and combination procedures are being described. This article in conjunction with the others in this issue, will try and explore the uses of collagen cross-linking (CXL in its current form.

  4. CULTURE CROSSING IN THE SCHOOL

    Directory of Open Access Journals (Sweden)

    María Padrós

    2009-11-01

    Full Text Available The educational centres are a multicultural reality that comprises the coexistenceof different cultural minorities, languages, religions, lifestyles and social codes.The critical pedagogy presents ways of living and learning in this culture crossing overcomingboth the ethnocentric model of racism (assimilation to the culture understood as“superior” as well as the relativist model (with emphasis on the difference and denyingequality, aiming for the idea of equality of differences. In the article are presented waysof crossing cultures and historical backgrounds from a critical, supportive and transformationalapproach among languages, religions and believes. It is stated that the consensusis possible in the framework of the plurality of identities and cultural patterns, andthat egalitarian dialog between cultures in the school promotes not only individualtransformations but also changes in the social relationships.

  5. Metonymy and Cross Section Demand

    OpenAIRE

    Evstigneev, Igor V.; Hildenbrand, Werner; Jerison, Michael

    1996-01-01

    Cross section consumer expenditure data are frequently used to make conclusions about consumer demand behavior. Such conclusions, however, can only be justified under certain assumptions, which are often left unstated in the empirical demand literature. An assumption of this type, the metonymy hypothesis, was stated rigorously and then exploited by Hardle, Hildenbrand and Jerison when analyzing the monotonicity property of aggregate demand functions. The purpose of the present paper is to exa...

  6. Wind Turbine Radar Cross Section

    OpenAIRE

    David Jenn; Cuong Ton

    2012-01-01

    The radar cross section (RCS) of a wind turbine is a figure of merit for assessing its effect on the performance of electronic systems. In this paper, the fundamental equations for estimating the wind turbine clutter signal in radar and communication systems are presented. Methods of RCS prediction are summarized, citing their advantages and disadvantages. Bistatic and monostatic RCS patterns for two wind turbine configurations, a horizontal axis three-blade design and a vertical axi...

  7. New Approach to Resonance Crossing

    OpenAIRE

    Franchetti, G.; Zimmermann, F.

    2012-01-01

    Time varying nonlinear oscillatory systems produce phenomena of resonance crossing and trapping of particles in resonance islands. Traditionally such processes have been analyzed in terms of adiabatic conditions. Considering, as an example, a simplified 1-dimensional (1-D) model describing the “electron cloud pinch” during a bunch passage in a particle accelerator, here we present an approach to resonance trapping which does not require any adiabatic condition. Instead we introduce the concep...

  8. A Crossing Method for Quinoa

    OpenAIRE

    Adam Peterson; Sven-Erik Jacobsen; Alejandro Bonifacio; Kevin Murphy

    2015-01-01

    As sustainable production of quinoa ( Chenopodium quinoa Willd.) increases and its geographic range of cultivation expands, quinoa breeding will allow use of the crop’s wide genetic diversity for cultivar improvement and for adaptation to new agroecosystems and climactic regimes. Such breeding work will require a reliable technique for crossing quinoa plants using hand emasculation. The technique described herein focuses on the isolation of small flower clusters produced low on the plant, e...

  9. CULTURE CROSSING IN THE SCHOOL

    OpenAIRE

    María Padrós; Itxaso Tellado

    2009-01-01

    The educational centres are a multicultural reality that comprises the coexistenceof different cultural minorities, languages, religions, lifestyles and social codes.The critical pedagogy presents ways of living and learning in this culture crossing overcomingboth the ethnocentric model of racism (assimilation to the culture understood as“superior”) as well as the relativist model (with emphasis on the difference and denyingequality), aiming for the idea of equality of differences. In the art...

  10. Cross-sectional Tobin's Q

    OpenAIRE

    Frederico Belo; Chen Xue; Lu Zhang

    2010-01-01

    The neoclassical investment model matches cross-sectional asset prices both in first differences and in levels. With ten book-to-market deciles as the testing portfolios, the investment model largely matches the Tobin's Q spread and the average return spread across the extreme deciles. The parameter estimates imply low adjustment costs around 1.7% of sales. The model's fit results from three aspects of our econometric strategy: (i) We test the model at the portfolio level to alleviate the imp...

  11. Cross-Cultural Knowledge Management

    CERN Document Server

    Giudice, Manlio Del; Peruta, Maria Rosaria Della

    2012-01-01

    Cross-cultural knowledge management, an elusive yet consequential phenomenon, is becoming an increasingly essential factor in organizational practice and policy in the era of globalization. In order to overcome culturally shaped blind spots in conducting research in different settings, this volume highlights how the structuring of roles, interests, and power among different organizational elements, such as teams, departments, and management hierarchies (each comprised of members from different intellectual and professional backgrounds), generates various paradoxes and tensions that bring into

  12. Electron-Impact Ionization Cross Section Database

    Science.gov (United States)

    SRD 107 Electron-Impact Ionization Cross Section Database (Web, free access)   This is a database primarily of total ionization cross sections of molecules by electron impact. The database also includes cross sections for a small number of atoms and energy distributions of ejected electrons for H, He, and H2. The cross sections were calculated using the Binary-Encounter-Bethe (BEB) model, which combines the Mott cross section with the high-incident energy behavior of the Bethe cross section. Selected experimental data are included.

  13. Crossing Intentions in Participatory Innovation

    DEFF Research Database (Denmark)

    Buur, Jacob; Larsen, Henry

    2010-01-01

    In this paper we explore the role of 'crossing intentions' among participants involved in innovation processes with users. We use improvised theatre to investigate what happens in industrial (and other) organizations that embark on participatory activities, and to explore the barriers that hinder...... the surface are experienced as risky to participate in. We examine four examples of such meetings with the intent to disclose conceptual themes that show high potential for developing participatory innovation.......In this paper we explore the role of 'crossing intentions' among participants involved in innovation processes with users. We use improvised theatre to investigate what happens in industrial (and other) organizations that embark on participatory activities, and to explore the barriers that hinder...... such activities. We propose that people who meet each other with different and conflicting intentions relevant to the theme together can create new insight (understood as movement of thought and action) that may become a driver of innovation. However, such meetings in which crossing intentions come to...

  14. Cross-border reprogenetic services.

    Science.gov (United States)

    Couture, V; Drouin, R; Tan, S-L; Moutquin, J-M; Bouffard, C

    2015-01-01

    The purpose of this review is to synthesize the current knowledge on the international movement of patients and biopsied embryo cells for pre-implantation genetic diagnosis and its different applications. Thus far, few attempts have been made to identify the specific nature of this phenomenon called 'cross-border reprogenetic services'. There is scattered evidence, both empirical and speculative, suggesting that these services raise major issues in terms of service provision, risks for patients and the children-to-come, the legal liabilities of physicians, as well as social justice. To compile this evidence, this review uses the narrative overview protocol combined with thematic analysis. Five major themes have emerged from the literature at the conjunction of cross-border treatments and reprogenetics: 'scope', 'scale', 'motivations', 'concerns', and 'governance'. Similar themes have already been observed in the case of other medical tourism activities, but this review highlights their singularity with reprogenetic services. It emphasizes the diagnostic and autologous feature of reprogenetics, the constant risk of misdiagnosis, the restriction on certain tests for medically controversial conditions, and the uncertain accessibility of genetic counseling in cross-border settings. PMID:24798608

  15. Microscopic cross sections: An utopia?

    Energy Technology Data Exchange (ETDEWEB)

    Hilaire, S. [CEA Bruyeres-le-Chatel, DIF 91 (France); Koning, A.J. [Nuclear Research and Consultancy Group, PO Box 25, 1755 ZG Petten (Netherlands); Goriely, S. [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles, Campus de la Plaine, CP 226, 1050 Brussels (Belgium)

    2010-07-01

    The increasing need for cross sections far from the valley of stability poses a challenge for nuclear reaction models. So far, predictions of cross sections have relied on more or less phenomenological approaches, depending on parameters adjusted to available experimental data or deduced from systematical relations. While such predictions are expected to be reliable for nuclei not too far from the experimentally known regions, it is clearly preferable to use more fundamental approaches, based on sound physical bases, when dealing with very exotic nuclei. Thanks to the high computer power available today, all major ingredients required to model a nuclear reaction can now be (and have been) microscopically (or semi-microscopically) determined starting from the information provided by a nucleon-nucleon effective interaction. We have implemented all these microscopic ingredients in the TALYS nuclear reaction code, and we are now almost able to perform fully microscopic cross section calculations. The quality of these ingredients and the impact of using them instead of the usually adopted phenomenological parameters will be discussed. (authors)

  16. Cross-border reprogenetic services.

    Science.gov (United States)

    Couture, V; Drouin, R; Tan, S-L; Moutquin, J-M; Bouffard, C

    2015-01-01

    The purpose of this review is to synthesize the current knowledge on the international movement of patients and biopsied embryo cells for pre-implantation genetic diagnosis and its different applications. Thus far, few attempts have been made to identify the specific nature of this phenomenon called 'cross-border reprogenetic services'. There is scattered evidence, both empirical and speculative, suggesting that these services raise major issues in terms of service provision, risks for patients and the children-to-come, the legal liabilities of physicians, as well as social justice. To compile this evidence, this review uses the narrative overview protocol combined with thematic analysis. Five major themes have emerged from the literature at the conjunction of cross-border treatments and reprogenetics: 'scope', 'scale', 'motivations', 'concerns', and 'governance'. Similar themes have already been observed in the case of other medical tourism activities, but this review highlights their singularity with reprogenetic services. It emphasizes the diagnostic and autologous feature of reprogenetics, the constant risk of misdiagnosis, the restriction on certain tests for medically controversial conditions, and the uncertain accessibility of genetic counseling in cross-border settings.

  17. CBP Customs Rulings Online Search System (CROSS)

    Data.gov (United States)

    Department of Homeland Security — CROSS is a searchable database of CBP rulings that can be retrieved based on simple or complex search characteristics using keywords and Boolean operators. CROSS...

  18. Quadratic and 2-Crossed Modules of Algebras

    Institute of Scientific and Technical Information of China (English)

    Z. Arvasi; E. Ulualan

    2007-01-01

    In this work, we define the quadratic modules for commutative algebras and give relations among 2-crossed modules, crossed squares, quadratic modules and simplicial commutative algebras with Moore complex of length 2.

  19. Discourse Issues in Cross-Cultural Pragmatics.

    Science.gov (United States)

    Boxer, Diana

    2002-01-01

    Focuses on recent research in cross-cultural pragmatics as distinct from interlanguage pragmatics. The essential difference between the two lies in the perspective from which each views cross-cultural communication. (Author/VWL)

  20. Generalized Cross-Gramian for Linear Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza

    2012-01-01

    The cross-gramian is a well-known matrix with embedded controllability and observability information. The cross-gramian is related to the Hankel operator and the Hankel singular values of a linear square system and it has several interesting properties. These properties make the cross...... square symmetric systems, the ordinary cross-gramian does not exist. To cope with this problem, a new generalized cross-gramian is introduced in this paper. In contrast to the ordinary cross-gramian, the generalized cross-gramian can be easily obtained for general linear systems and therefore can be used......-gramian popular in several applications including model reduction, control configuration selection and sensitivity analysis. The ordinary cross-gramian which has been defined in the literature is the solution of a Sylvester equation. This Sylvester equation is not always solvable and therefore for some linear...

  1. Navigation in Cross-cultural business relationships

    DEFF Research Database (Denmark)

    Andersen, Poul Houman

    2001-01-01

    Cross-cultural business navigation concerns the process of handling the complexity of several interacting cultural spheres of influence......Cross-cultural business navigation concerns the process of handling the complexity of several interacting cultural spheres of influence...

  2. Crossing Hazard Functions in Common Survival Models.

    Science.gov (United States)

    Zhang, Jiajia; Peng, Yingwei

    2009-10-15

    Crossing hazard functions have extensive applications in modeling survival data. However, existing studies in the literature mainly focus on comparing crossed hazard functions and estimating the time at which the hazard functions cross, and there is little theoretical work on conditions under which hazard functions from a model will have a crossing. In this paper, we investigate crossing status of hazard functions from the proportional hazards (PH) model, the accelerated hazard (AH) model, and the accelerated failure time (AFT) model. We provide and prove conditions under which the hazard functions from the AH and the AFT models have no crossings or a single crossing. A few examples are also provided to demonstrate how the conditions can be used to determine crossing status of hazard functions from the three models.

  3. Web Based Cross Language Plagiarism Detection

    OpenAIRE

    Kent, Chow Kok; Salim, Naomie

    2009-01-01

    As the Internet help us cross language and cultural border by providing different types of translation tools, cross language plagiarism, also known as translation plagiarism are bound to arise. Especially among the academic works, such issue will definitely affect the student's works including the quality of their assignments and paper works. In this paper, we propose a new approach in detecting cross language plagiarism. Our web based cross language plagiarism detection system is specially t...

  4. Electrospinning formaldehyde cross-linked zein solutions

    Science.gov (United States)

    In order to develop zein fibers with improved physical properties and solvent resistance, formaldehyde was used as the cross-linking reagent before spinning. The cross-linking reaction was carried out in either acetic acid or ethanolic-HCl where the amount of cross-linking reagent was between 1 and...

  5. A Cross-Cultural Training Manual.

    Science.gov (United States)

    Silc, Kathleen Flannery, Ed.; And Others

    Designed to accompany a Cross-Cultural Training Workshop for supervisors of limited-English-proficient (LEP) employees, this "train the trainer" manual can be used as a resource for individuals who have some experience as cross-cultural trainers or as an orientation for novices in the area of cross-cultural communication. The workshop is intended…

  6. Cross-border merger and domestic welfare

    OpenAIRE

    Arijit Mukherjee

    2006-01-01

    We consider the welfare effect of cross-border merger in presence of international R&D competition. Cross-border merger increases domestic welfare if the bargaining power of the foreign firm and the slope of the marginal cost of R&D are sufficiently low. Otherwise, domestic welfare is lower under cross-border merger.

  7. Cross-language information retrieval

    CERN Document Server

    Nie, Jian-Yun

    2010-01-01

    Search for information is no longer exclusively limited within the native language of the user, but is more and more extended to other languages. This gives rise to the problem of cross-language information retrieval (CLIR), whose goal is to find relevant information written in a different language to a query. In addition to the problems of monolingual information retrieval (IR), translation is the key problem in CLIR: one should translate either the query or the documents from a language to another. However, this translation problem is not identical to full-text machine translation (MT): the

  8. Wind Turbine Radar Cross Section

    Directory of Open Access Journals (Sweden)

    David Jenn

    2012-01-01

    Full Text Available The radar cross section (RCS of a wind turbine is a figure of merit for assessing its effect on the performance of electronic systems. In this paper, the fundamental equations for estimating the wind turbine clutter signal in radar and communication systems are presented. Methods of RCS prediction are summarized, citing their advantages and disadvantages. Bistatic and monostatic RCS patterns for two wind turbine configurations, a horizontal axis three-blade design and a vertical axis helical design, are shown. The unique electromagnetic scattering features, the effect of materials, and methods of mitigating wind turbine clutter are also discussed.

  9. Level crossing for hot sphalerons

    CERN Document Server

    Ambjørn, Jan; Hands, S; Koutsoumbas, G; Thorleifsson, G

    1994-01-01

    We study the spectrum of the Dirac Hamiltonian in the presence of high temperature sphaleron-like fluctuations of the electroweak gauge and Higgs fields, relevant for the conditions prevailing in the early universe. The fluctuations are created by numerical lattice simulations. It is shown that a change in Chern-Simons number by one unit is accompanied by eigenvalues crossing zero and a change of sign of the generalized chirality $\\tGf= (-1)^{2T+1} \\gf$ which labels these modes. This provides further evidence that the sphaleron-like configurations observed in lattice simulations may be viewed as representing continuum configurations.

  10. Large amplitude motion of the acetylene molecule within acetylene-neon complexes hosted in helium droplets.

    Science.gov (United States)

    Briant, M; Mengesha, E; de Pujo, P; Gaveau, M-A; Soep, B; Mestdagh, J-M; Poisson, L

    2016-06-28

    Superfluid helium droplets provide an ideal environment for spectroscopic studies with rotational resolution. Nevertheless, the molecular rotation is hindered because the embedded molecules are surrounded by a non-superfluid component. The present work explores the dynamical role of this component in the hindered rotation of C2H2 within the C2H2-Ne complex. A HENDI experiment was built and near-infrared spectroscopy of C2H2-Ne and C2H2 was performed in the spectral region overlapping the ν3/ν2 + ν4 + ν5 Fermi-type resonance of C2H2. The comparison between measured and simulated spectra helped to address the above issue. PMID:27263427

  11. The CrossGrid project

    Science.gov (United States)

    Kunze, M.; CrossGrid Collaboration

    2003-04-01

    There are many large-scale problems that require new approaches to computing, such as earth observation, environmental management, biomedicine, industrial and scientific modeling. The CrossGrid project addresses realistic problems in medicine, environmental protection, flood prediction, and physics analysis and is oriented towards specific end-users: Medical doctors, who could obtain new tools to help them to obtain correct diagnoses and to guide them during operations; industries, that could be advised on the best timing for some critical operations involving risk of pollution; flood crisis teams, that could predict the risk of a flood on the basis of historical records and actual hydrological and meteorological data; physicists, who could optimize the analysis of massive volumes of data distributed across countries and continents. Corresponding applications will be based on Grid technology and could be complex and difficult to use: the CrossGrid project aims at developing several tools that will make the Grid more friendly for average users. Portals for specific applications will be designed, that should allow for easy connection to the Grid, create a customized work environment, and provide users with all necessary information to get their job done.

  12. Cross delay line sensor characterization

    Energy Technology Data Exchange (ETDEWEB)

    Owens, Israel J [Los Alamos National Laboratory; Remelius, Dennis K [Los Alamos National Laboratory; Tiee, Joe J [Los Alamos National Laboratory; Buck, Steven E [Los Alamos National Laboratory; Whittemore, Stephen R [Los Alamos National Laboratory; Thompson, David C [Los Alamos National Laboratory; Shirey, Robert [Los Alamos National Laboratory

    2010-01-01

    There exists a wealth of information in the scientific literature on the physical properties and device characterization procedures for complementary metal oxide semiconductor (CMOS), charge coupled device (CCD) and avalanche photodiode (APD) format detectors. Numerous papers and books have also treated photocathode operation in the context of photomultiplier tube (PMT) operation for either non imaging applications or limited night vision capability. However, much less information has been reported in the literature about the characterization procedures and properties of photocathode detectors with novel cross delay line (XDL) anode structures. These allow one to detect single photons and create images by recording space and time coordinate (X, Y & T) information. In this paper, we report on the physical characteristics and performance of a cross delay line anode sensor with an enhanced near infrared wavelength response photocathode and high dynamic range micro channel plate (MCP) gain (> 10{sup 6}) multiplier stage. Measurement procedures and results including the device dark event rate (DER), pulse height distribution, quantum and electronic device efficiency (QE & DQE) and spatial resolution per effective pixel region in a 25 mm sensor array are presented. The overall knowledge and information obtained from XDL sensor characterization allow us to optimize device performance and assess capability. These device performance properties and capabilities make XDL detectors ideal for remote sensing field applications that require single photon detection, imaging, sub nano-second timing response, high spatial resolution (10's of microns) and large effective image format.

  13. Geosynchronous magnetopause crossings: upstream conditions

    CERN Document Server

    Suvorova, A; Chao, J -K; Thomsen, M; Yang, Y -H

    2011-01-01

    The experimental data on GOES magnetic measurements and plasma measurements on LANL geosynchronous satellites is used for selection of 169 case events containing 638 geosynchronous magnetopause crossings (GMCs) in 1995 to 2001. We study the necessary conditions for the geosynchronous magnetopause crossings using scatter plot of the GMCs in the coordinate space of Psw versus Bz. In such representation the upstream solar wind conditions demonstrate sharp envelope boundary under which no GMCs are occurred. The boundary has two strait horizontal branches where Bz does not influence on the magnetopause location. The first branch is located in the range of Psw=21 nPa for large positive Bz and is associated with an asymptotic regime of the pressure balance. The second branch asymptotically approaches to the range of Psw=4.8 nPa under very strong negative Bz and it is associated with a regime of the Bz influence saturation. We suggest that the saturation is caused by relatively high contribution of the magnetosphere ...

  14. Dentists and cross-infection.

    Science.gov (United States)

    Naidoo, S

    1997-03-01

    A structured questionnaire was administered to a random sample of general dental practitioners in Natal, South Africa in 1994, to ascertain the precautions they use against cross-infection and to gauge the attitudes and behaviour towards the treatment of HIV-infected individuals. An interview was conducted covering 5 broad topics: demographic details, personal barrier protection, instrument sterilization and disinfection, sharps disposal and incidence of needlestick injuries and the extent of the knowledge, attitude and behaviour of the practitioners toward the treatment of HIV-infected individuals. The key findings were: routine glove wearing, for all patients, was practised by 87 per cent. The most common heat sterilization method was by autoclave (68 per cent), although a dry heat sterilizer and water boiler were used by 22 per cent of the respondents. Of the 18 respondents reporting a needlestick injury in the past 6 months only one sought after-care. 42 per cent of the respondents would continue to treat carriers of HIV in their practices. This survey shows that a significant number of dentists are using unacceptable cross-infection control procedures. Educational efforts should be made to improve their knowledge and to alleviate anxiety of health workers to treat HIV-infected patients. PMID:9461908

  15. CrossFlow: Cross-Organizational Workflow Management in Dynamic Virtual Enterprises

    NARCIS (Netherlands)

    Grefen, Paul; Aberer, Karl; Hoffner, Yigal; Ludwig, Heiko

    2000-01-01

    In this report, we present the approach to cross-organizational workflow management of the CrossFlow project. CrossFlow is a European research project aiming at the support of cross-organizational workflows in dynamic virtual enterprises. The cooperation in these virtual enterprises is based on dyna

  16. CrossFlow: Cross-Organizational Workflow Management in Dynamic Virtual Enterprises

    NARCIS (Netherlands)

    Grefen, Paul; Aberer, Karl; Hoffner, Yigal; Ludwig, Heiko

    2000-01-01

    This paper gives a detailed overview of the approach to cross-organizational workflow management developed in the CrossFlow project. CrossFlow is a European research project aiming at the support of cross-organizational workflows in dynamic virtual enterprises. The cooperation in these virtual enter

  17. CrossFlow: Cross-Organizational Workflow Management for Service Outsourcing in Dynamic Virtual Enterprises

    NARCIS (Netherlands)

    Grefen, Paul; Aberer, Karl; Ludwig, Heiko; Hoffner, Yigal

    2001-01-01

    In this report, we present the approach to cross-organizational workflow management of the CrossFlow project. CrossFlow is a European research project aiming at the support of cross-organizational workflows in dynamic virtual enterprises. The cooperation in these virtual enterprises is based on dyna

  18. CrossWork: Software-assisted identification of cross-linked peptides

    DEFF Research Database (Denmark)

    Rasmussen, Morten; Refsgaard, Jan; Peng, Li;

    2011-01-01

    Work searches batches of tandem mass-spectrometric data, and identifies cross-linked and non-cross-linked peptides using a standard PC. We tested CrossWork by searching mass-spectrometric datasets of cross-linked complement factor C3 against small (1 protein) and large (1000 proteins) search spaces, and show...

  19. Deionization shocks in cross flows

    Science.gov (United States)

    Mani, Ali

    2011-11-01

    Recent experimental and theoretical studies have shown that surface conduction in supported electrolytes, such as in micro/nanochannels or porous media, can lead to nonlinear modes of transport and formation of sharp concentration fronts analogous to shock waves in gas dynamics. Propagation of these shocks leaves behind a region of ultra pure fluid, acting to deionize the bulk solution. In this work we present the analysis of salt transport in a porous medium next to a membrane with an electric field applied normal to the interface and cross flow in tangential direction. We show that two distinct boundary layers grow near the membrane: an inner (shocked) region with almost deionized solution dominated by surface conduction, and an outer layer with diffuse dynamics. Under certain conditions both regions collapse into a similarity solution with the same scaling. We will discuss advantages of such systems for desalination and water purification. Research performed in collaboration with Martin Bazant (MIT).

  20. H2S 为毒物对乙炔氢氯化反应中 AuCl3/AC 催化剂催化活性的影响%Poisoning effect of H2S on catalytic performance of AuCl3/AC in acetylene hydrochlorination

    Institute of Scientific and Technical Information of China (English)

    代斌; 张春丽; 康丽华; 朱明远

    2015-01-01

    A study about poisoning effect of hydrogen sulfide (H2S) on the catalytic performance of AuCl3/AC during acetylene hydrochlorination deactivation is described and discussed. 1% AuCl3/AC catalyst is prepared by an incipient wetness impregnation technique. The activity tests demonstrate that H2S poisoning results in the rapid and irreversible deactivation of AuCl3/AC catalyst in acetylene hydrochlorination. Temperature-programmed reduction (TPR) and X-ray photoelectron spectra (XPS) show that H2S addition can effectively accelerate active Au3+ reduction to metallic Au0. The formation of metal sulfide may also be another reason for catalyst deactivation in the presence of H2S, which is supported by transmission electron microscopy (TEM) and energy dispersion X-ray spectrometer (EDX) techniques. In other words, with the increase of H2S added to the feed gases, the content of Au3+ is greatly reduced to metallic Au0. Moreover, the active sites are covered with Au-S compound. Both of them could reduce the effective active component, leading to the deactivation of the AuCl3/AC catalyst.%采用等体积浸渍法制备了 1% AuCl3/AC 催化剂,探究了硫化氢(H2S)为毒物对乙炔氢氯化反应中催化剂催化活性的影响及失活机理.催化活性测试结果表明,以 H2S 为毒物可导致乙炔氢氯化反应中的 AuCl3/AC 催化剂的失活,且是一个不可逆过程;程序升温还原(TPR)和 X 射线光电子能谱(XPS)分析结果表明,H2S 的加入可有效地加快 Au3+还原为 Au0;透射电镜能谱(TEM-EDX)观测分析形成的 Au-S 化合物也可导致催化剂失活,即随着 H2S 量的增大,更多的 Au3+被还原为 Au0,且形成的 Au-S 化合物覆盖在活性位点,使有效的活性组分降低进而导致 AuCl3/AC 催化剂失活.

  1. The link between border crossing and obesity.

    Science.gov (United States)

    Molina, Marisa A; Ayala, Guadalupe X; Baquero, Barbara; Madanat, Hala; Garcini, Luz

    2015-04-01

    Research examining border crossing and health has focused on substance abuse, healthcare utilization and air pollution. Living in border communities allows for frequent crossing and exposure to different sociocultural and structural environments. Given high rates of obesity among Latinos and the large percentage living in border communities, it is important to consider the relationship between border crossing and obesity. This study explored the relationship between frequency of border crossing, obesigenic behaviors, measured obesity, and chronic disease. Multistage sampling methods were used to recruit 397 Latino adults living in border communities in South San Diego County. Selected participants completed a face-to-face interview and height and weight measurements. More frequent border crossing was associated with more fast food consumption and a greater reported diagnosis of high cholesterol. Understanding the extent to which border crossing is associated with obesigenic behaviors and chronic disease is important for developing relevant interventions along the border. PMID:24442511

  2. Dynamical systems associated with crossed products

    CERN Document Server

    Svensson, Christian; de Jeu, Marcel

    2007-01-01

    In this paper, we consider both algebraic crossed products of commutative complex algebras A with the integers under an automorphism of A, and Banach algebra crossed products of commutative C^*-algebras A with the integers under an automorphism of A. We investigate, in particular, connections between algebraic properties of these crossed products and topological properties of naturally associated dynamical systems. For example, we draw conclusions about the ideal structure of the crossed product by investigating the dynamics of such a system. To begin with, we recall results in this direction in the context of an algebraic crossed product and give simplified proofs of generalizations of some of these results. We also investigate new questions, for example about ideal intersection properties of algebras properly between the coefficient algebra A and its commutant A'. Furthermore, we introduce a Banach algebra crossed product and study the relation between the structure of this algebra and the topological dynam...

  3. Background-cross-section-dependent subgroup parameters

    International Nuclear Information System (INIS)

    A new set of subgroup parameters was derived that can reproduce the self-shielded cross section against a wide range of background cross sections. The subgroup parameters are expressed with a rational equation which numerator and denominator are expressed as the expansion series of background cross section, so that the background cross section dependence is exactly taken into account in the parameters. The advantage of the new subgroup parameters is that they can reproduce the self-shielded effect not only by group basis but also by subgroup basis. Then an adaptive method is also proposed which uses fitting procedure to evaluate the background-cross-section-dependence of the parameters. One of the simple fitting formula was able to reproduce the self-shielded subgroup cross section by less than 1% error from the precise evaluation. (author)

  4. Measurements of neutron capture cross sections

    International Nuclear Information System (INIS)

    A review of measurement techniques for the neutron capture cross sections is presented. Sell transmission method, activation method, and prompt gamma-ray detection method are described using examples of capture cross section measurements. The capture cross section of 238U measured by three different prompt gamma-ray detection methods (large liquid scintillator, Moxon-Rae detector, and pulse height weighting method) are compared and their discrepancies are resolved. A method how to derive the covariance is described. (author)

  5. Crossing Statistics of Anisotropic Stochastic Surface

    CERN Document Server

    Nezhadhaghighi, M Ghasemi; Yasseri, T; Allaei, S M Vaez

    2015-01-01

    We use crossing statistics and its generalization to determine the anisotropic direction imposed on a stochastic fields in $(2+1)$Dimension. This approach enables us to examine not only the rotational invariance of morphology but also we can determine the Gaussianity of underlying stochastic field in various dimensions. Theoretical prediction of up-crossing statistics (crossing with positive slope at a given threshold $\\alpha$ of height fluctuation), $\

  6. Cross Sections for Electron Collisions with Methane

    Energy Technology Data Exchange (ETDEWEB)

    Song, Mi-Young, E-mail: mysong@nfri.re.kr; Yoon, Jung-Sik [Plasma Technology Research Center, National Fusion Research Institute, 814-2 Osikdo-dong, Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Cho, Hyuck [Department of Physics, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Itikawa, Yukikazu [Institute of Space and Astronautical Science, Sagamihara 252-5210 (Japan); Karwasz, Grzegorz P. [Faculty of Physics, Astronomy and Applied Informatics, University Nicolaus Copernicus, Grudziadzka 5, 87100 Toruń (Poland); Kokoouline, Viatcheslav [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Nakamura, Yoshiharu [6-1-5-201 Miyazaki, Miyamae, Kawasaki 216-0033 (Japan); Tennyson, Jonathan [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-06-15

    Cross section data are compiled from the literature for electron collisions with methane (CH{sub 4}) molecules. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2014.

  7. Cosmetic crossings of genus one knots

    CERN Document Server

    Balm, Cheryl

    2011-01-01

    We show that for genus one knots the Alexander polynomial and the homology of the double cover branching over the knot provide obstructions to cosmetic crossings. As an application we prove the nugatory crossing conjecture for the negatively twisted, positive Whitehead doubles of all knots. We also verify the conjecture for several families of pretzel knots and all genus one knots with up to 10 crossings.

  8. Piano Crossing - Generating music using computer vision

    OpenAIRE

    Lipanje, Matevž

    2010-01-01

    Piano Crossing is an interactive art installation which transforms the zebra crossing into a working piano keyboard where pedestrians generate music by walking across it. Installation consists of the zeboard - zebra crossing turned keyboard - by adding black stripes to the existing white ones, serving as keys, a digital camera overlooking the zeboard and of a laptop computer with speakers. The computer runs a specially designed software, which recognizes pedestrian's contacts with the keys by...

  9. Cross-platform mobile game development

    OpenAIRE

    Pirttiaho, Joonas

    2014-01-01

    The main purpose of this thesis was to find and learn about a framework for cross-platform mobile game development for modern mobile operating systems. The target mobile platforms were Google's Android and Apple's iOS. The thesis was started by finding out different types of solutions for cross-platform application and game development for mobile devices. Different types of solutions should be briefly described and the found solution for cross-platform development should be more extensive...

  10. Teaching NHCE with Cross-Cultural Simulations

    Institute of Scientific and Technical Information of China (English)

    杨非

    2008-01-01

    Cross-cultural communication competence is very important for the students who study English as a second language. In order to teach effectively.the teachers may try to teach with cross-cultural simulations.The au- thor Of the article uses 5 simulations in the course of New Horizon College English.Although the sample size in this research is small,the author shows the ideas that cross-cultural awareness is related to communication competence and teaching with cross-cultural simulations helps understanding.

  11. Ion and electron impact ionization cross sections

    International Nuclear Information System (INIS)

    Several current projects are described in which cross sections of interest to radiation physics are being measured. These include total and multiple ionization cross sections for protons on several gases covering a wide energy range, the measurement of cross sections differential in the angle and energy of ejected electrons for several gases including water vapor, and a review of proton ionization data. The work on water vapor has also been extended to electron and neutral hydrogen impact. A brief discussion is also given of some systematics of ionization cross sections. 13 references

  12. Damage cross section library (DAMSIG77)

    International Nuclear Information System (INIS)

    The damage cross sections of various materials are converted to a data format, which can be used as library for the program SAND-II. The materials available in this library are graphite, stainless steel, aluminium, silicium, chromium, iron, nickel, copper, zirconium, molybdenum, tungsten, vanadium and niobium. A number of these materials have more than one cross section set, originating from different evaluations. Cross sections for some activation reactions, commonly used to determine thermal and fast neutron fluences have been included too. Moreover, also some artificial cross sections are introduced in this library which can be used to derive values for some physical quantities which may characterize neutron spectra

  13. [Fast neutron cross section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Knoll, G.F.

    1992-10-26

    From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are clean'' and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its data production'' phase.

  14. Cross-training policies and team performance

    NARCIS (Netherlands)

    Slomp, J.; Molleman, E.

    2002-01-01

    Labour flexibility is an important issue in the design and development of teams. By means of an analytical study this paper investigates the impact of cross-training on team performance. Four cross-training policies are distinguished and compared according to their effects on important performance m

  15. The Cross-Referenced Patent Cooperation Treaty

    NARCIS (Netherlands)

    Mulder, C.A.M.

    2015-01-01

    'The Cross-Referenced Patent Cooperation Treaty' is a book covering the 'Patent Cooperation Treaty (PCT)' and the 'Regulations under the PCT'. The large number of references in the articles and rules makes the PCT difficult to read. The idea behind this book is to add cross-references to the article

  16. The Cross-Referenced Patent Cooperation Treaty

    NARCIS (Netherlands)

    Mulder, C.A.M.

    2012-01-01

    'The Cross-Referenced Patent Cooperation Treaty' is a book covering the 'Patent Cooperation Treaty (PCT)' and the 'Regulations under the PCT'. The large number of references in the articles and rules makes the PCT difficult to read. The idea behind this book is to add cross-references to the article

  17. The cross-Referenced Patent Cooperation Treaty

    NARCIS (Netherlands)

    Mulder, C.A.M.

    2014-01-01

    'The Cross-Referenced Patent Cooperation Treaty' is a book covering the 'Patent Cooperation Treaty (PCT)' and the 'Regulations under the PCT'. The large number of references in the articles and rules makes the PCT difficult to read. The idea behind this book is to add cross-references to the article

  18. The Cross-Referenced Patent Cooperation Treaty

    NARCIS (Netherlands)

    Mulder, C.A.M.

    2013-01-01

    'The Cross-Referenced Patent Cooperation Treaty' is a book covering the 'Patent Cooperation Treaty (PCT)' and the 'Regulations under the PCT'. The large number of references in the articles and rules makes the PCT difficult to read. The idea behind this book is to add cross-references to the article

  19. The Cross-Referenced Patent Cooperation Treaty

    NARCIS (Netherlands)

    Mulder, C.A.M.

    2009-01-01

    'The Cross-Referenced Patent Cooperation Treaty' is a book covering the 'Patent Cooperation Treaty (PCT)' and the 'Regulations under the PCT'. The large number of references in the articles and rules makes the PCT difficult to read. The idea behind this book is to add cross-references to the article

  20. Linear Unlearning for Cross-Validation

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Larsen, Jan

    1996-01-01

    The leave-one-out cross-validation scheme for generalization assessment of neural network models is computationally expensive due to replicated training sessions. In this paper we suggest linear unlearning of examples as an approach to approximative cross-validation. Further, we discuss the...... time series prediction benchmark demonstrate the potential of the linear unlearning technique...

  1. Nucleon-XcJ Dissociation Cross Sections

    Institute of Scientific and Technical Information of China (English)

    冯又层; 许晓明; 周代翠

    2002-01-01

    Nucleon-XcJ dissociation cross sections are calculated in a constituent interexchange model in which quark-quark potential is derived from the Buchmüller-Tye quark-anti-quark potential. These new cross sections for dominant reaction channels depend on the centre-of-mass energy of the nucleon and the charmonium.

  2. Commutativity and ideals in category crossed products

    DEFF Research Database (Denmark)

    Öinert, Per Johan; Lundström, Patrik

    2010-01-01

    In order to simultaneously generalize matrix rings and group graded crossed products, we introduce category crossed products. For such algebras we describe the centre and the commutant of the coefficient ring. We also investigate the connection between on the one hand maximal commutativity of the...

  3. Cross-cultural difference in OSH

    NARCIS (Netherlands)

    Starren, A.; Drupsteen, L.

    2014-01-01

    In this article we describe cross-cultural aspects in the context of safety management. When working abroad, cross-cultural differences ask for other competencies to enhance safe behaviour than at home due to cultural and language differences. In this wiki some guidance is given on aspects of cultur

  4. Water Treatment Technology - Cross-Connections.

    Science.gov (United States)

    Ross-Harrington, Melinda; Kincaid, G. David

    One of twelve water treatment technology units, this student manual on cross connections provides instructional materials for two competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on cross connections terminology and control devices. For each…

  5. Chemical cross-linking of Chlamydia trachomatis

    DEFF Research Database (Denmark)

    Birkelund, Svend; Lundemose, AG; Christiansen, Gunna

    1988-01-01

    Purified elementary bodies (EBs) of Chlamydia trachomatis serovar L2 were analyzed by chemical cross-linking with disuccinimidyl selenodipropionate. The effect of the cross-linking was analyzed by immunoblotting sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated components which...

  6. Curriculum Integration and Cross-Cultural Psychology.

    Science.gov (United States)

    Goldstein, Susan B.

    While many undergraduate disciplines are revising curricula to address issues of diversity more effectively, it is commonly assumed that courses in cross-cultural psychology are less in need of revision due to their inherent multi-cultural focus. The field of cross-cultural psychology, however, is not immune to Eurocentric and androcentric biases.…

  7. Study of Politeness in Cross Cultural Communication

    Institute of Scientific and Technical Information of China (English)

    桂仁娜; 姜艳

    2012-01-01

      Politeness is a universal linguistic phenomenon but also relative by nature and subject to culture. The politeness in pragmatic study and its cultural specificity in cross cultural communication are explained. Some tactics in cross communication are also suggested.

  8. Border Crossing Monitoring along the Northern Corridor

    OpenAIRE

    Fitzmaurice, Mike; Hartmann, Olivier

    2013-01-01

    Border-crossing times in East Africa have been identified as a major constraint for smooth trade flows, both for regional trade and for international transit. Delays at borders disrupt efficient trade logistics, impacting on the transport costs and prices, and ultimately on trade competitiveness. In order to improve the efficiency of border crossings in East Africa, the East Africa Communi...

  9. 47 CFR 15.605 - Cross reference.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Cross reference. 15.605 Section 15.605 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Access Broadband Over Power Line (Access BPL) § 15.605 Cross reference. (a) The provisions of subparts A and B of this part apply to...

  10. Cross-cultural Knowledge Management

    Directory of Open Access Journals (Sweden)

    Dorel Mihai PARASCHIV

    2009-01-01

    Full Text Available The success of international companies in providing high quality products and outstanding services is subject, on the one hand, to the increasing dynamic of the economic environment and on the other hand to the adoption of worldwide quality standards and procedures. As market place is becoming more and more global, products and services offered worldwide by international companies must face the multi-cultural environment challenges. These challenges manifest themselves not only at customer relationship level but also deep inside companies, at employee level. Important support in facing all these challenges has been provided at cognitive level by management system models and at technological level by information cutting edge technologies Business Intelligence & Knowledge Management Business Intelligence is already delivering its promised outcomes at internal business environment and, with the explosive deployment of public data bases, expand its analytical power at national, regional and international level. Quantitative measures of economic environment, wherever available, may be captured and integrated in companies’ routine analysis. As for qualitative data, some effort is still to be done in order to integrate measures of social, political, legal, natural and technological environment in companies’ strategic analysis. An increased difficulty is found in treating cultural differences, common knowledge making the most hidden part of any foreign environment. Managing cultural knowledge is crucial to success in cultivating and maintaining long-term business relationships in multicultural environments. Knowledge Management provides the long needed technological support for cross-cultural management in the tedious task of improving knowledge sharing in multi-national companies and using knowledge effectively in international joint ventures. The paper is approaching the conceptual frameworks of knowledge management and proposes an unified model

  11. Crossing point temperature of coal

    Institute of Scientific and Technical Information of China (English)

    Qi Xuyao; Deming Wang; James A. Milke; Xiaoxing Zhong

    2011-01-01

    A further understanding of the self-heating of coal was obtained by investigating the crossing point temperature (CPT) of different ranks of coal. The tests were carried out using a self-designed experimental system for coal self-heating. 50 g (±0.01 g) of coal particles ranging from 0.18 mm to 0.38 mm in size were put into a pure copper reaction vessel attached to the center of a temperature programmed enclosure. The temperature program increased the temperature at a rate of 0.8 ℃/min. Dry air was permitted to flow into the coal reaction vessel at different rates. The surrounding temperature and the coal temperature were monitored by a temperature logger. The results indicate that CPT is affected by coal rank, moisture, sulfur,and the experimental conditions. Higher ranked coals show higher CPT values. A high moisture content causes a delay phenomenon during the self-heating of the coal. Drying at 40 ℃ decreases the effects of moisture. The reactivity of sulfur components in the coal is low under dry and low-temperature conditions.These components form a film that covers the coal surface and slightly inhibits the self-heating of the coal.The flow rate of dry air, and the heating rate of the surroundings, also affect the self-heating of the coal. The most appropriate experimental conditions for coal samples of a given weight and particle size were determined through contrastive analysis. Based on this analysis we propose that CPTs be determined under the same, or nearly the same conditions, for evaluation of the spontaneous combustion of coal.

  12. Recommended evaluation procedure for photonuclear cross section

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Ouk; Chang, Jonghwa; Fukahori, Tokio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    In order to generate photonuclear cross section library for the necessary applications, data evaluation is combined with theoretical evaluation, since photonuclear cross sections measured cannot provide all necessary data. This report recommends a procedure consisting of four steps: (1) analysis of experimental data, (2) data evaluation, (3) theoretical evaluation and, if necessary, (4) modification of results. In the stage of analysis, data obtained by different measurements are reprocessed through the analysis of their discrepancies to a representative data set. In the data evaluation, photonuclear absorption cross sections are evaluated via giant dipole resonance and quasi-deutron mechanism. With photoabsorption cross sections from the data evaluation, theoretical evaluation is applied to determine various decay channel cross sections and emission spectra using equilibrium and preequilibrium mechanism. After this, the calculated results are compared with measured data, and in some cases the results are modified to better describe measurements. (author)

  13. Robust optimisation of railway crossing geometry

    Science.gov (United States)

    Wan, Chang; Markine, Valeri; Dollevoet, Rolf

    2016-05-01

    This paper presents a methodology for improving the crossing (frog) geometry through the robust optimisation approach, wherein the variability of the design parameters within a prescribed tolerance is included in the optimisation problem. Here, the crossing geometry is defined by parameterising the B-spline represented cross-sectional shape and the longitudinal height profile of the nose rail. The dynamic performance of the crossing is evaluated considering the variation of wheel profiles and track alignment. A multipoint approximation method (MAM) is applied in solving the optimisation problem of minimising the contact pressure during the wheel-rail contact and constraining the location of wheel transition at the crossing. To clarify the difference between the robust optimisation and the normal deterministic optimisation approaches, the optimisation problems are solved in both approaches. The results show that the deterministic optimum fails under slight change of the design variables; the robust optimum, however, has improved and robust performance.

  14. Probing the dynamics of polyatomic multichannel elementary reactions by crossed molecular beam experiments with soft electron-ionization mass spectrometric detection.

    Science.gov (United States)

    Casavecchia, Piergiorgio; Leonori, Francesca; Balucani, Nadia; Petrucci, Raffaele; Capozza, Giovanni; Segoloni, Enrico

    2009-01-01

    In this Perspective we highlight developments in the field of chemical reaction dynamics. Focus is on the advances recently made in the investigation of the dynamics of elementary multichannel radical-molecule and radical-radical reactions, as they have become possible using an improved crossed molecular beam scattering apparatus with universal electron-ionization mass spectrometric detection and time-of-flight analysis. These improvements consist in the implementation of (a) soft ionization detection by tunable low-energy electrons which has permitted us to reduce interfering signals originating from dissociative ionization processes, usually representing a major complication, (b) different beam crossing-angle set-ups which have permitted us to extend the range of collision energies over which a reaction can be studied, from very low (a few kJ mol(-1), as of interest in astrochemistry or planetary atmospheric chemistry) to quite high energies (several tens of kJ mol(-1), as of interest in high temperature combustion systems), and (c) continuous supersonic sources for producing a wide variety of atomic and molecular radical reactant beams. Exploiting these new features it has become possible to tackle the dynamics of a variety of polyatomic multichannel reactions, such as those occurring in many environments ranging from combustion and plasmas to terrestrial/planetary atmospheres and interstellar clouds. By measuring product angular and velocity distributions, after having suppressed or mitigated, when needed, the problem of dissociative ionization of interfering species (reactants, products, background gases) by soft ionization detection, essentially all primary reaction products can be identified, the dynamics of each reaction channel characterized, and the branching ratios determined as a function of collision energy. In general this information, besides being of fundamental relevance, is required for a predictive description of the chemistry of these

  15. Cross polarization caused by perturbed circular cross sections of waveguides and horn antennas

    Science.gov (United States)

    Lier, Erik

    1987-03-01

    The cross polarization caused by a perturbed cross section of the conical hybrid-mode horn is analyzed. The perturbed cross section is assumed to be slightly elliptical. The theory of Lier and Bergh (1986) for cross polarization in a smooth-walled waveguide supporting the TE11-mode is referred and applied to the HE11 mode as well. Simple analytical formulas which are sufficiently accurate for small ellipticites of the cross-section ellipse are presented. These show that the tolerances on the waveguide diameter are extremely strong, typically on the order of 0.02-0.04 mm in the horn throat for typical horn geometries at 12 GHz.

  16. Piano Crossing – Walking on a Keyboard

    Directory of Open Access Journals (Sweden)

    Bojan Kverh

    2010-11-01

    Full Text Available Piano Crossing is an interactive art installation which turns a pedestrian crossing marked with white stripes into a piano keyboard so that pedestrians can generate music by walking over it. Matching tones are created when a pedestrian steps on a particular stripe or key. A digital camera is directed at the crossing from above. A special computer vision application was developed, which maps the stripes of the pedestrian crossing to piano keys and detects by means of an image over which key the center of gravity of each pedestrian is placed at any given moment. Black stripes represent the black piano keys. The application consists of two parts: (1 initialization, where the model of the abstract piano keyboard is mapped to the image of the pedestrian crossing, and (2 the detection of pedestrians at the crossing, so that musical tones can be generated according to their locations. The art installation Piano crossing was presented to the public for the first time during the 51st Jazz Festival in Ljubljana in July 2010.

  17. Cross-spectrally pure light, cross-spectrally pure fields and statistical similarity in electromagnetic fields

    Science.gov (United States)

    Chen, Jingjing; Lu, RongSheng; Chen, Feinan; Li, Jia

    2014-08-01

    This paper describes the concept of cross-spectrally pure light, implications of statistical similarity of an optical field on its cross-spectral purity and cross-spectrally pure fields. First, the concept of cross-spectral purity of light is analysed in the space-frequency domain by taking into account the vectorial nature of the radiation, and the conditions and reduction formula are obtained. Then, by utilizing statistical similarity, the relationship between cross-spectral purity and spatial coherence is explored in the electromagnetic field. Last, the conditions for cross-spectrally pure fields are discussed, the polychromatic plane wave and the far field produced by a planar, secondary, stochastic electromagnetic source are studied as examples, and moreover, the relationship between cross-spectral purity and spatial coherence, which we have drawn, is verified during the study.

  18. Vehicle routing with cross-docking

    DEFF Research Database (Denmark)

    Wen, Min; Larsen, Jesper; Clausen, Jens;

    2009-01-01

    a set of homogeneous vehicles are used to transport orders from the suppliers to the corresponding customers via a cross-dock. The orders can be consolidated at the cross-dock but cannot be stored for very long because the cross-dock does not have long-term inventory-holding capabilities. The objective...... of the VRPCD is to minimize the total travel time while respecting time window constraints at the nodes and a time horizon for the whole transportation operation. In this paper, a mixed integer programming formulation for the VRPCD is proposed. A tabu search heuristic is embedded within an adaptive memory...... values) within very short computational time....

  19. METROBORDER. Cross-border Polycentric Metropolitan Regions

    DEFF Research Database (Denmark)

    Walther, Olivier

    -border polycentric metropolitan region. However, cross-border areas appear to be systematically underestimated in their development opportunities so that awareness about specific advantages needs to be improved. This is why this project addresses cross-border metropolitan regions in Europe in relation to the policy......Metropolitan regions are generally seen as drivers for territorial development in the national context, as well as drivers for economic, social and cultural development on a European and global scale. Many border regions dispose of specific potentials but also specific barriers for a cross...

  20. Degenerated codimension 1 crossings and resolvent estimates

    CERN Document Server

    Duyckaerts, Thomas; Jecko, Thierry

    2008-01-01

    In this article, we analyze the propagation of Wigner measures of a family of solutions to a system of semi-classical pseudodifferential equations presenting eigenvalues crossings on hypersurfaces. We prove the propagation along classical trajectories under a geometric condition which is satisfied for example as soon as the Hamiltonian vector fields are transverse or tangent at finite order to the crossing set. We derive resolvent estimates for semi-classical Schr\\"odinger operator with matrix-valued potential under a geometric condition of the same type on the crossing set and we analyze examples of degenerate situations where one can prove transfers between the modes.

  1. Inclined-cross Microstructure of Conch Shell

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The microstructures of conch shell were observed with scanning electronic microscope (SEM),and a kind of inclined-cross microstructure of aragonite sheets was found. The maximal pull-out force of the inclined-cross microstructure was analyzed based on its representative model and compared with that of a conventional0°-structure. The experimental result indicates that the maximal pull-out force of the inclined-cross microstructure is markedly larger than that of the 0 °-structure.

  2. Cross-border regional innovation systems

    DEFF Research Database (Denmark)

    Makkonen, Teemu; Rohde, Stephan

    2016-01-01

    The concept of cross-border regional innovation systems (CBRIS) surfaced in the literature on economic geography through discourses that highlighted the need of broadening innovation systems to cross-border contexts. Since these early discussions, the theoretical backgrounds of CBRIS have been...... elaborated through notions of geographical scale, proximity and related variety in a range of conceptual papers proposing CBRIS as a comprehensive framework for analysing regional cross-border integration. However, the empirical literature on CBRIS has failed to keep up with the advances in conceptualisation...

  3. Irrational Rotation Algebra as a Crossed Product

    Directory of Open Access Journals (Sweden)

    S. Haghkhah

    2006-03-01

    Full Text Available In this paper we will consider the crossed product C(T ×α Z, where T is the unit circle, α(n = αn is a rotation through the angle −2πnθ for n ∈ Z, and θ is a fixed irrational number. We will apply some results about patial actions to represent this crossed product as a C ∗ -subalgebra of B(L 2 (T. Also, by a different method form the proof of Davidson, we show that this crossed product is isomorphic to the irrational rotation algebra.

  4. Parents' Attitudes and Expectations about Children's Cross-Gender Behavior.

    Science.gov (United States)

    Sandnabba, N. Kenneth; Ahlberg, Christian

    1999-01-01

    Assessed parents' attitudes toward cross-gender behavior of boys and girls. Responses of 224 white Finnish parents of 5-year olds reveal that cross-gender boys are regarded more negatively than cross-gender girls. Men perceived more societal acceptance of cross-gender boys than did women. It is thought that cross-gender boys were more likely to…

  5. An application of the explicit method for analysing intersystem dependencies in the evaluation of event trees

    International Nuclear Information System (INIS)

    A computacional application of the explicit method for analyzing event trees in the context of probabilistic risk assessments is discussed. A detailed analysis of the explicit method is presented, including the train level analysis (TLA) of safety systems and the impact vector method. It is shown that the penalty for not adopting TLA is that in some cases non-conservative results may be reached. The impact vector method can significantly reduce the number of sequences to be considered, and its use has inspired the definition of a dependency matrix, which enables the proper running of a computer code especially developed for analysing event trees. The code has been extensively used in the Angra 1 PRA currently underway. In its present version it gives as output the dominant sequences for each given initiator, properly classiying them in core-degradation classes as specified by the user. (Author)

  6. Corporate Social Responsibility in the Dynamic Information Age of Inter-Systems Connectivity

    OpenAIRE

    Arvind Ashta

    2009-01-01

    The Information Age, with its new technologies, is accompanied by an accelerating shift in work relations, of which this article focuses on connectivity, interdependence and dynamism. Along with this change in relations, new ethical cultures and responsibilities are evolving at different levels: individual, corporate, governmental, NGO, and global. This article zooms in on theoretical developments related to Corporate Social Responsibility to see how they have evolved to adapt to the new mode...

  7. Transition probability of the Si III 189.2-nm intersystem line

    Science.gov (United States)

    Kwong, H. S.; Johnson, B. C.; Smith, P. L.; Parkinson, W. H.

    1983-01-01

    Measurement of the lifetime of the metastable 3s3p(3)P(0)1 level of Si(2+) (Si III), which decays by photon emission at 189.2 nm to the 3s2(1)S0 state, is reported. The data were taken from spontaneous emission from metastable Si III stored in an RF ion trap. The Si III ions were produced through electron bombardment of SiH4 and SiF4 at pressures of 1/100,000,000-1/10,000,000 Torr. A photomultiplier was employed to count the photon emissions from the transitions. A total of 11 decay curves were generated for analysis, with Poisson statistics used to set the uncertainties at within 8 pct. Significant systematic effects were controlled, and the lifetime was found to be within 3.6 microsec of 59.9 microsec. The method used is concluded valid for determining the lifetimes of metastable levels of low-Z ions with low charge, and thereby the transition probabilities.

  8. Obstacle crossing in lower limb amputees

    NARCIS (Netherlands)

    Vrieling, A.H.; van Keeken, H.G.; Schoppen, Tanneke; Otten, Egbert; Halbertsma, J.P.; Hof, A.L.; Postema, K.

    2007-01-01

    Objective: To study limitations in function and adjustment strategies in lower limb amputees during obstacle crossing. Design: Observational cohort study. Subjects: Transfemoral and transtibial amputees and able-bodied control subjects. Methods: In a motion analysis laboratory unimpeded and obstacle

  9. Seeds of Cross-Media Production

    DEFF Research Database (Denmark)

    Bødker, Susanne; Petersen, Anja Bechmann

    2007-01-01

    We present an empirical study of an organization that has recently moved from traditional newspaper production towards cross-media production involving the integrated digital production of newspaper, television, radio and web-news. The paper focuses on the daily production rhythms of the media...... separately and of cross-media production. Since cross-media production is in the making, we study the instruments currently used for planning and coordination, and analyze them as seeds that will eventually make cross-media production happen. Time and timing are important in news production in general......, and our analyses focus on the rhythm of the daily planning, coordination and production processes. Specifically, we analyze the temporal coordination of the activities in and around the Superdesk – the current center of coordination of the news organization, and of the persons who work specifically...

  10. Environmental Aesthetics. Crossing Divides and Breaking Ground

    NARCIS (Netherlands)

    Drenthen, M.; Keulartz, J.

    2014-01-01

    Environmental aesthetics crosses several commonly recognized divides: between analytic and continental philosophy, Eastern and Western traditions, universalizing and historicizing approaches, and theoretical and practical concerns. This volume sets out to show how these,perspectives can be brought i

  11. Differential cross sections of positron hydrogen collisions

    Institute of Scientific and Technical Information of China (English)

    于荣梅; 濮春英; 黄晓玉; 殷复荣; 刘旭焱; 焦利光; 周雅君

    2016-01-01

    We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical (CCO) method for incident energies below the H ionization threshold. The target continuum and the positronium (Ps) formation channels are included in the coupled-channels calculations via a complex equivalent-local optical potential. The critical points, which show minima in the differential cross sections, as a function of the scattering angle and the incident energy are investigated. The resonances in the angular differential cross sections are reported for the first time in this energy range. The effects of the target continuum and the Ps formation channels on the different cross sections are discussed.

  12. Web Based Cross Language Plagiarism Detection

    CERN Document Server

    Kent, Chow Kok

    2009-01-01

    As the Internet help us cross language and cultural border by providing different types of translation tools, cross language plagiarism, also known as translation plagiarism are bound to arise. Especially among the academic works, such issue will definitely affect the student's works including the quality of their assignments and paper works. In this paper, we propose a new approach in detecting cross language plagiarism. Our web based cross language plagiarism detection system is specially tuned to detect translation plagiarism by implementing different techniques and tools to assist the detection process. Google Translate API is used as our translation tool and Google Search API, which is used in our information retrieval process. Our system is also integrated with the fingerprint matching technique, which is a widely used plagiarism detection technique. In general, our proposed system is started by translating the input documents from Malay to English, followed by removal of stop words and stemming words, ...

  13. A nuclear cross section data handbook

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, H.O.M.

    1989-12-01

    Isotopic information, reaction data, data availability, heating numbers, and evaluation information are given for 129 neutron cross-section evaluations, which are the source of the default cross sections for the Monte Carlo code MCNP. Additionally, pie diagrams for each nuclide displaying the percent contribution of a given reaction to the total cross section are given at 14 MeV, 1 MeV, and thermal energy. Other information about the evaluations and their availability in continuous-energy, discrete-reaction, and multigroup forms is provided. The evaluations come from ENDF/B-V, ENDL85, and the Los Alamos Applied Nuclear Science Group T-2. Graphs of all neutron and photon production cross-section reactions for these nuclides have been categorized and plotted. 21 refs., 5 tabs.

  14. CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    S. Goodin

    1999-07-08

    The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches.

  15. Systematics of (n,2n) Cross Sections

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The experimental data of (n, 2n) cross sections were collected and evaluated as complete as possible. There are 640 sets of experimental data for 130 nuclei. The data were fitted to the expressions that describe the

  16. Refined Multifractal Cross-Correlation Analysis

    CERN Document Server

    Oświȩcimka, Paweł; Forczek, Marcin; Jadach, Stanisław; Kwapień, Jarosław

    2013-01-01

    We propose a modified algorithm - Multifractal Cross-Correlation Analysis (MFCCA) - that is able to consistently identify and quantify multifractal cross-correlations between two time series. Our motivation for introducing this algorithm is that the already existing methods like MF-DXA have serious limitations for most of the signals describing complex natural processes. The principal component of the related improvement is proper incorporation of the sign of fluctuations. We present a broad analysis of the model fractal stochastic processes as well as of the real-world signals and show that MFCCA is a robust tool and allows a reliable quantification of the cross-correlative structure of analyzed processes. We, in particular, analyze a relation between the generalized Hurst exponent and the MFCCA parameter $\\lambda_q$. This relation provides information about the character of potential multifractality in cross-correlations of the processes under study and thus enables selective insight into their dynamics. Us...

  17. Cross- cultural Communication in Business English

    Institute of Scientific and Technical Information of China (English)

    罗雪

    2014-01-01

    The factors in cross - cultural communication affects business activities should be paid attention through the process of learning Business English. The successful communication can be realized through the identity with inter- culture.

  18. Cross-Disciplinary Collaboration and Learning

    Directory of Open Access Journals (Sweden)

    Deana D. Pennington

    2008-12-01

    Full Text Available Complex environmental problem solving depends on cross-disciplinary collaboration among scientists. Collaborative research must be preceded by an exploratory phase of collective thinking that creates shared conceptual frameworks. Collective thinking, in a cross-disciplinary setting, depends on the facility with which collaborators are able to learn and understand each others' perspectives. This paper applies three perspectives on learning to the problem of enabling cross-disciplinary collaboration: Maslow's hierarchy of needs, constructivism, and organizational learning. Application of learning frameworks to collaboration provides insights regarding receptive environments for collaboration, and processes that facilitate cross-disciplinary interactions. These environments and interactions need time to develop and require a long phase of idea generation preceding any focused research effort. The findings highlight that collaboration is itself a complex system of people, scientific theory, and tools that must be intentionally managed. Effective management of the system requires leaders who are facilitators and are capable of orchestrating effective environments and interactions.

  19. Average Cross Section Evaluation - Room for Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Frohner, G.H. [Forschungszentrum Karlsruhe Institut fur Kern- und Energietechnik, Karlsruhe (Germany)

    2006-07-01

    Full text of publication follows: Techniques for evaluation of average nuclear cross sections are well established. Nevertheless there seems room for improvement. Heuristic expressions for average partial cross sections of the Hauser-Feshbach type with width fluctuation corrections could be replaced by the correct GOE triple integral. Transmission coefficients derived from macroscopic models (optical, single and double hump fission barrier, etc) lead to better descriptions of cross section behaviour over wide energy ranges. At higher energies (n,{gamma}n') reactions compete with radiative capture (Moldauer effect). In all cross section modeling one must distinguish properly between average S- and R-matrix parameters. The exact relationship between them is given, as well as the connection to Endf format rules. Fitting codes (e.g. FITACS) should be able to digest observed data directly, instead of only reduced data corrected already for self shielding and multiple scattering (e.g. with SESH). (author)

  20. Conflict in cross-functional teams

    OpenAIRE

    Vieira, Nuno Fradique

    2006-01-01

    The present study is a qualitative analysis of the tensions that occur in cross-functional teams (CFTs) and the way in which they can affect the teams' accomplishments. The research is focused on a single case, COHTTEC 2005, a program aimed at transforming new technologies into businesses that took place in Lisbon, Portugal, starting March 2005. In this program, participants were organized in cross-functional teams that included researchers and management students. Semi-structured intervie...

  1. Normal Crossings Degenerations of Symplectic Manifolds

    CERN Document Server

    Tehrani, Mohammad Farajzadeh

    2016-01-01

    We use local Hamiltonian torus actions to degenerate a symplectic manifold to a normal crossings symplectic variety in a smooth one-parameter family. This construction, motivated in part by the Gross-Siebert and B. Parker's programs, contains a multifold version of the usual (two-fold) symplectic cut construction and in particular splits a symplectic manifold into several symplectic manifolds containing normal crossings symplectic divisors with shared irreducible components in one step.

  2. Cross-cultural Context and Politeness

    Institute of Scientific and Technical Information of China (English)

    朱芬

    2012-01-01

    In social interaction,politeness is a universal phenomenon existing in all languages.However,for social,ethnographic and even historical reasons,politeness strategies in a specific cultural context may vary from one to another.And for most time it is not language itself but different politeness strategies that lead to cross-cultural communicative failure.Knowing about these differences will help to overcome pragmatic failure in cross-cultural communication.

  3. Seafarer Cross-Generational Competence Skills

    OpenAIRE

    Tyron, Olena

    2014-01-01

    It was mentioned that the ability to establish a positive relationship between the members of international crews is an urgent issue. This ability influences not only the safety of navigation, but the mental health of seafarers as well. Foreign language competence is essential for the resolution of this problem. Successful everyday communication of seafarers depends on a number of factors: the awareness of cross-cultural, religious and cross-generational differences will help establish a frie...

  4. A Theory of Cross-Validation Error

    OpenAIRE

    Turney, Peter D.

    2002-01-01

    This paper presents a theory of error in cross-validation testing of algorithms for predicting real-valued attributes. The theory justifies the claim that predicting real-valued attributes requires balancing the conflicting demands of simplicity and accuracy. Furthermore, the theory indicates precisely how these conflicting demands must be balanced, in order to minimize cross-validation error. A general theory is presented, then it is developed in detail for linear regression a...

  5. Neutron capture cross sections from Surrogate measurements

    OpenAIRE

    Scielzo N.D.; Dietrich F.S.; Escher J.E.

    2010-01-01

    The prospects for determining cross sections for compound-nuclear neutron-capture reactions from Surrogate measurements are investigated. Calculations as well as experimental results are presented that test the Weisskopf-Ewing approximation, which is employed in most analyses of Surrogate data. It is concluded that, in general, one has to go beyond this approximation in order to obtain (n,γ) cross sections of sufficient accuracy for most astrophysical and nuclear-energy applications.

  6. Neutron capture cross sections from Surrogate measurements

    Directory of Open Access Journals (Sweden)

    Scielzo N.D.

    2010-03-01

    Full Text Available The prospects for determining cross sections for compound-nuclear neutron-capture reactions from Surrogate measurements are investigated. Calculations as well as experimental results are presented that test the Weisskopf-Ewing approximation, which is employed in most analyses of Surrogate data. It is concluded that, in general, one has to go beyond this approximation in order to obtain (n,γ cross sections of sufficient accuracy for most astrophysical and nuclear-energy applications.

  7. Abelian crossed modules and strict Picard categories

    OpenAIRE

    Quang, Nguyen Tien; Phung, Che Thi Kim; Tung, Ngo Sy

    2013-01-01

    In this paper, we state the notion of morphisms in the category of abelian crossed modules and prove that this category is equivalent to the category of strict Picard categories and regular symmetric monoidal functors. The theory of obstructions for symmetric monoidal functors and symmetric cohomology groups are applied to show a treatment of the group extension problem of the type of an abelian crossed module.

  8. Cross-Cultural Human Resource Management

    OpenAIRE

    Pu, Jing

    2010-01-01

    In the 21st century, many international companies have rushed into China. In the fierce competition, the winners will be companies who know China and Chinese people. Cross-cultural Human Resource Management becomes a “must” for international companies in this situation. There is much literature about Cross-Cultural Human Resource Management, but they discuss in this field generally instead of specifically guilds for international companies; in real practice, there are many companies lost mana...

  9. Cross-platform mobile app development

    OpenAIRE

    Magiels, Seppe

    2015-01-01

    In dit eindwerk onderzoeken we of het gebruik maken van een cross-platform framework het ontwikkelingsproces van mobiele applicaties kan vereenvoudigen. We bespreken verschillende cross-platform frameworks die zowel Android als iOS ondersteunen. Twee van deze frameworks, Xamarin en Qt, worden diepgaander besproken en vergeleken. Voor deze vergelijking maken we gebruik van een case study. Deze is gebaseerd op de Yelo applicatie van Telenet en werd ontwikkeld i.s.m. Androme. Qt en Xamarin w...

  10. Cross-cultural differences in faking

    OpenAIRE

    Clemens B. Fell

    2016-01-01

    Due to globalization, organizations face the challenges of international personnel selection. Systematic cross-cultural differences in applicants’ behavior are a threat for the utility and fairness of personnel selection. This dissertation is the first to examine on a large scale how countries’ cultural characteristics can explain cross-cultural differences in faking behavior. Across three large-scale studies, meaningful country-level relationships between culture and faking were identified. ...

  11. Cross-Shareholdings and Information Environment

    OpenAIRE

    Katsuhiko Muramiya; Tomomi Takada

    2015-01-01

    We examine the relationship between cross-shareholdings and the information environment. This issue is important because the separation of ownership and control al- lows managers to act exclusively in their own interests. Despite numerous studies on the influences of other types of ownership structures, including family, institutional investor, and block ownership structures, little is known about how cross-shareholdings influence management incentives. We highlight the Japanese market, where...

  12. Methods for calculating anisotropic transfer cross sections

    International Nuclear Information System (INIS)

    The Legendre moments of the group transfer cross section, which are widely used in the numerical solution of the transport calculation can be efficiently and accurately constructed from low-order (K = 1--2) successive partial range moments. This is convenient for the generation of group constants. In addition, a technique to obtain group-angle correlation transfer cross section without Legendre expansion is presented. (author)

  13. The cross-border cooperation agreement

    OpenAIRE

    Cătălin-Silviu SĂRARU

    2011-01-01

    This study aims to achieve a short analysis of cross-border cooperation agreements between territorial-administrative units in the border areas of Romania and similar structures in neighboring states. The article investigates the form they takes these agreements – contract or treaty –, the role of multinational enterprises and the law applicable to transnational contracts, the cross-border cooperation agreement governed by Law no. 215/2001 on local public administration and its legal nature. ...

  14. Does ATP cross the cell plasma membrane.

    OpenAIRE

    Chaudry, I. H.

    1982-01-01

    Although there is an abundance of evidence which indicates that ATP is released as well as taken up by cells, the concept that ATP cannot cross the cell membrane has tended to prevail. This article reviews the evidence for the release as well as uptake of ATP by cells. The evidence presented by various investigators clearly indicates that ATP can cross the cell membrane and suggests that the release and uptake of ATP are physiological processes.

  15. Transdisciplinary Application of Cross-Scale Resilience

    OpenAIRE

    Shana M. Sundstrom; David G Angeler; Ahjond S. Garmestani; Jorge H. García; Allen, Craig R.

    2014-01-01

    The cross-scale resilience model was developed in ecology to explain the emergence of resilience from the distribution of ecological functions within and across scales, and as a tool to assess resilience. We propose that the model and the underlying discontinuity hypothesis are relevant to other complex adaptive systems, and can be used to identify and track changes in system parameters related to resilience. We explain the theory behind the cross-scale resilience model, review the cases wher...

  16. Evaluation methods for neutron cross section standards

    International Nuclear Information System (INIS)

    Methods used to evaluate the neutron cross section standards are reviewed and their relative merits, assessed. These include phase-shift analysis, R-matrix fit, and a number of other methods by Poenitz, Bhat, Kon'shin and the Bayesian or generalized least-squares procedures. The problems involved in adopting these methods for future cross section standards evaluations are considered, and the prospects for their use, discussed. 115 references, 5 figures, 3 tables

  17. Cross Entropy Approximation of Structured Covariance Matrices

    OpenAIRE

    Liou, Cheng-Yuan; Musicus, Bruce R.

    2006-01-01

    We apply two variations of the principle of Minimum Cross Entropy (the Kullback information measure) to fit parameterized probability density models to observed data densities. For an array beamforming problem with P incident narrowband point sources, N > P sensors, and colored noise, both approaches yield eigenvector fitting methods similar to that of the MUSIC algorithm[1]. Furthermore, the corresponding cross-entropies are related to the MDL model order selection criterion[2].

  18. Pedestrian Crossing Speed: The Case of Malaysia

    Directory of Open Access Journals (Sweden)

    Boon Hoe Goh

    2012-12-01

    Full Text Available Pedestrians are vulnerable road users, and they are always at risk when making their daily trips. Hence, roadway design and traffic’ control devices need to consider pedestrians’ safety. Pedestrian walking speed is fundamental to any roadway and traffic’ control design. Unfortunately, no specific guidelines exist for pedestrian crossing speed in Malaysia. The ultimate goals of this research are to establish the local pedestrian crossing speed and to identify the contributing factors. A total of 1579 samples on pedestrian crossing speed were collected at signalized and non-signalized crosswalks. The Bi-variate analysis (chi-square test was carried out to study statistically the association of the contributing factors. The Bi-variate analysis shows that crosswalk type, age and gender significantly contribute to pedestrian speed in Malaysia. However, lighting (daytime and night-time and race are not contributing to the pedestrians’ speed. Besides, pedestrians at non-signalized crosswalk have significantly faster crossing speed than at signalized crosswalk. Chi-square test also showed that children pedestrians are the fastest group, and elderly pedestrians are the slowest group in terms of pedestrian crossing speed. Moreover, male pedestrians have significantly faster crossing speed than female pedestrians do.

  19. A DFT and multi-configurational perturbation theory study on O2 binding to a model heme compound via the spin-change barrier.

    Science.gov (United States)

    Kitagawa, Y; Chen, Y; Nakatani, N; Nakayama, A; Hasegawa, J

    2016-07-21

    Dioxygen binding to a model heme compound via intersystem crossing (ISC) was investigated with a multi-state multi-configurational self-consistent field method with second-order perturbation theory (MS-CASPT2) and density functional theory (DFT) calculations. In elongated Fe-O distances, the energy levels of the S0 and T1 states are separated, which decreases the probability of intersystem crossing in these structures. At the DFT(B97D) level of calculation, the Fe-O distances of the S0 and T1 states were 1.91 and 2.92 Å, respectively. The minimum energy intersystem crossing point (MEISCP) was located as a transition state at a Fe-O distance of 2.17 Å with an energy barrier of 1.0 kcal mol(-1) from the T1 minimum. The result was verified with MS-CASPT2 calculations including the spin-orbit interaction which also showed the intersystem crossing point at a Fe-O distance of 2.05 Å. An energy decomposition analysis on the reaction coordinate showed the important contribution of the ring-shrinking mode of the porphyrin ring, indicating that the reaction coordinates which control the relative energy level of the spin-states play a key role in intersystem crossing. PMID:27328181

  20. Effects of Exogenous Acetylene on Floral Bud Differentiation and Endogenous Hormone Content of Guzmania‘Denise’%乙炔催花对凤梨‘丹尼斯’花芽分化及内源激素含量的影响

    Institute of Scientific and Technical Information of China (English)

    段九菊; 曹冬梅; 王丽萍; 张超; 王云山

    2012-01-01

    为了探讨凤梨开花的生理机制以及为凤梨花期调控提供理论依据,以凤梨‘丹尼斯’为试材,研究乙炔催花对其花芽分化及内源激素含量的影响。结果表明:乙炔催花7天后诱导‘丹尼斯’进入花芽分化状态,其花芽分化进程可分为花芽未分化期、花序原基分化期、花原基分化期、花萼花瓣分化期、雌雄蕊分化期。在整个花芽分化过程中,植株生长点及叶片中生长素(IAA)、脱落酸(ABA)含量未见明显改变,而玉米素核苷(ZRs)在花序原基分化期和花原基分化期呈现出2次显著增加,赤霉素(GAs)含量在花序原基分化期和器官分化早期显著下降,从而引起ABA/GAs、ZRs/GAs、ZRs/IAA比值在花序原基分化期、花原基分化期和器官分化早期显著增加。因此,高水平的ZRs含量、ABA/GAs、ZRs/GAs、ZRs/IAA比值以及低水平的GAs含量有利于凤梨‘丹尼斯’花芽分化的完成。%In order to study the flowering mechanism in Bromeliaceae, and to provide a theoretical basis for flowering regulation, the effects of exogenous acetylene on floral bud differentiation and endogenous hormone contents of Guzmania‘Denise’were investigated. The results showed that: Guzmania‘Denise’was introduced into floral bud differentiation stage by exogenous acetylene application 7 days. The process of bud differentiation included no differentiation stage, inflorescence primordium differentation stage, single flower primordium differentiation stage, sepal and petal differentiation stage and stamen and pistil differentiation stage. During the process of bud differentiation, the contents of auxins (IAA) and abscisic acid (ABA) in the growing point and leaves kept mostly unchangeable. However, the contents of zeatin nucleotides (ZRs) increased significantly in inflorescence primordium differentation stage and single flower primordium differentiation stage. The contents of