Enriched reaction center preparation from green photosynthetic bacteria. [Chlorobium limicola

Energy Technology Data Exchange (ETDEWEB)

Olson, J M; Giddings, Jr, T H; Shaw, E K

1976-01-01

Bacteriochlorophyll a reaction-center complex I from Chlorobium limicola f. thiosulfatophilum 6230 (Tassajara) was incubated in 2 M guanidine . HCl and then chromatographed on cross-linked dextran or agarose gel. Two principal components were separated: a larger component with photochemical activity (bacteriochlorophyll a reaction-center complex II) and a smaller component without activity (bacteriochlorophyll a protein). Complex II contains carotenoid, bacteriochlorophyll a, reaction center(s), and cytochromes b and c, but lacks the well characterized bacteriochlorophyll a protein contained in Complex I. Complex II carries out a light-induced reduction of cytochrome b along with an oxidation of cytochrome c.

Small-angle neutron polarization for the /sup 2/H(d vector,n vector)/sup 3/He reaction near Esub(d) = 8MeV

Energy Technology Data Exchange (ETDEWEB)

Tornow, W.; Woye, W.; Mack, G. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Walter, R.L.; Floyd, C.E.; Guss, P.P.; Byrd, R.C. (Duke Univ., Durham, NC (USA). Dept. of Physics; Triangle Universities Nuclear Lab., Durham, NC (USA))

1981-12-15

Considerable improvement in the quality of analyzing power experiments performed with polarized fast neutrons has been achieved during the last few years by using neutrons from the polarization transfer reaction /sup 2/H(d vector,n vector)/sup 3/He at a reaction angle of theta = 0/sup 0/. To compromise in these experiments between intensity problems and finite geometry corrections, it is desirable in some instances to subtend a full-width angle ..delta..theta of 20/sup 0/ (lab) centered about theta = 0/sup 0/. In order to investigate the suitability of this reaction as a source of polarized neutrons for cases where the scatterer is close to the neutron source, the neutron polarization of the reaction /sup 2/H(d vector,n vector)/sup 3/He has been studied with ..delta..theta of about 3/sup 0/ in 3/sup 0/ steps out to theta = 20/sup 0/ (lab). An incident deuteron energy near 8 MeV was chosen to yield outgoing neutrons at 11.0 MeV, a typical energy for neutron analyzing power experiments. It is found that the effective neutron polarization, a combination of the two polarizations measured when the direction of the deuteron polarization is inverted or flipped at the polarized ion source, is large and nearly constant for angles between theta = 0/sup 0/ and theta = 10/sup 0/ (lab).

Reactions of carbon radicals generated by 1,5-transposition of reactive centers

Directory of Open Access Journals (Sweden)

ZIVORAD CEKOVIC

2005-03-01

Full Text Available Radical intermediates can undergo specific reactions, such as intramolecular rearrangements, i.e., the transpositions of radical centers, which are not known in classical ionic organic reactions. 1,5-Transposition of a radical center to a non-activated carbon atom are of great synthetic importance. It can be successfully applied for the introduction of different functional groups (oxygen, nitrogen, sulfur, halogens onto a carbon atom remote from the present functional group. In addition to functionalization of a remote non-activated carbon atom, the formation of new C-C bonds on the d-carbon atom have also been achieved. 1,5-Transposition of the radical centers takes place from alkoxyl, aminyl and carbon radicals to a remote carbon atom. Relocation of the radical centers preferentially involves 1,5-transfer of a hydrogen atom, although migrations of some other groups are known. The reactions of the carbon radical generated by 1,5-relocation of the radical center are presented and their synthetic applications are reviewed.

An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium-catalyzed multi-component domino reaction

Directory of Open Access Journals (Sweden)

Gohain Mukut

2006-06-01

Full Text Available Abstract Various novel pyrano [2,3-d]pyrimidines 5 and furopyrano [2,3-d]pyrimidines 7 were synthesized in 80–99% yields via a multicomponent domino Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III chloride. The reaction also proceeds in aqueous media without using any catalyst, but the yield is comparatively less (65–70%.

Discussion of isomeric ratios in (p, n) and (d, 2n) reaction

Energy Technology Data Exchange (ETDEWEB)

Bakhshiyan, T. M., E-mail: tiruhi44@mail.ru [Yerevan State University (Armenia)

2016-01-15

Isomeric ratios (IR) in the (p, n) and (d, 2n) reactions are considered. The dependence of IR values on the projectile type and energy, the target- and product-nucleus spin, the spin difference between the isomeric and ground states of products, and the product mass number is discussed. The isomeric ratios for 46 product nuclei (from {sup 44m,g}Sc to {sup 127m,g}Xe) obtained in reactions where target and product nuclei have identical mass numbers were calculated at energies from the reaction threshold to 50 MeV (with a step of ΔE = 1 MeV). The calculations in question were performed with the aid of the TALYS 1.4 code package. The calculated IR values were compared with their experimental counterparts available from the literature (EXFOR database). In the majority of cases, the calculated IR values agree well with the experimental data in question. It is noteworthy that the IR values obtained in (d, 2n) reactions are substantially greater than those in (p, n) reactions.

Measurement of astrophysical S-factors and electron screening potentials for d(d,n)3He reaction in ZrD2, TiD2 and TaD0.5 targets in the ultralow energy region using plasma accelerator

International Nuclear Information System (INIS)

Bystritsky, V.M.; Bystritskii, Vit.M.; Dudkin, G.N.; Filipowicz, M.; Gazi, S.; Huran, J.; Kobzev, A.P.; Mesyats, G.A.; Nechaev, B.A.; Padalko, V.N.; Parzhitskii, S.S.; Pen'kov, F.M.; Philippov, A.V.; Kaminskii, V.L.; Tuleushev, Yu.Zh.; Wozniak, J.

2012-01-01

The present paper is devoted to the study of the electron screening effect influence on the rate of d(d,n) 3 He reaction in the ultralow deuteron collision energy range in the deuterated metals (ZrD 2 , TiD 2 and TaD 0.5 ). The ZrD 2 , TiD 2 and TaD0.5 targets were fabricated via magnetron sputtering of titanium, zirconium and tantalum in gas (deuterium) environment. The experiments have been carried out using the high-current pulsed Hall plasma accelerator (NSR TPU, Russia). The detection of neutrons with energy of 2.5 MeV from the dd reaction was done with plastic scintillation spectrometers. As a result of the experiments, the energy dependences of the astrophysical S-factor for the dd reaction in the deuteron collision energy range of 2-7 keV and the values of the electron screening potential U e of the interacting deuterons have been measured for the above targets: U e (ZrD 2 )=(205±35) eV; U e (TiD 2 )=(125±34) eV; U e (TaD 0.5 )=(313±58) eV. Our results are compared with the other published experimental and calculated data.

2H(d,p)3H and 2H(d,n)3He reactions at sub-coulomb energies

International Nuclear Information System (INIS)

Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Spartá, R.; Aliotta, M.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Mrazek, J.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

2012-01-01

The 2 H( 3 He,p 3 H) 1 H and 2 H( 3 He,n 3 He) 1 H processes have been measured in quasi free kinematics to investigate for the first time the 2 H(d,p) 3 H and 2 H(d,n) 3 He reactions by means of the Trojan Horse Method. The 3 He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4±1.8 MeVb for 3 H+p and 60.1±1.9 MeVb for 3 He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

H/D exchange in the reaction of D2 with Bis(triphenyl phosphite)(acetylacetonato)rhodium(I), Rh(P(OPh)3)2(acac)

International Nuclear Information System (INIS)

Whitmore, B.C.; Eisenberg, R.

1984-01-01

The reaction of Rh(P)OPh) 3 ) 2 (acac) (1) with D 2 benzene has been studied by 1 H NMR spectroscopy, and complex 1 has been found to undergo H/D exchange at the ortho positions of the coordinated phosphite ligands and at the central methine position of the acetylacetonate ligand. At 75 0 C, the exchange reaction proceeds with the extent of deuterium incorporation into P(OPh) 3 being the same as that into acac at all stages of the H/D exchange process. At 60 0 C, deuterium incorporation into P(OPh) 3 is initially more rapid than that into the acac ligand. The initial rate of deuterium incorporation into P(OPh) 3 by 1 in benzene-d 6 under D 2 at 60 0 C proceeds with a first-order rate constant of 9.6 x 10 -5 s -1 . A mechanism for this exchange process is proposed. 13 references, 3 figures, 2 tables

Hydrogenation/Deoxygenation (H/D Reaction of Furfural-Acetone Condensation Product using Ni/Al2O3-ZrO2 Catalyst

Directory of Open Access Journals (Sweden)

Adam Mahfud

2016-08-01

Full Text Available The catalytic hydrogenation/deoxygenation (H/D reaction was carried out using Ni/Al2O3-ZrO2 catalyst. The 10% (wt/wt of Ni were impregnated on Al2O3-ZrO2 (10NiAZ by wet impregnation method followed by calcination and reduction. X-Ray diffraction analysis showed that Nideposited on the surface, with specific surface areas (SBET was 48.616 m2/g. Catalyst performance were evaluated for H/D reaction over furfural-acetone condensation products, mixture of 2-(4-furyl-3-buten-2-on and 1,5-bis-(furan-2-yl-pentan-3-one. The reaction was carried out in a batch, performed at 150°C for 8 hours. The H/D reaction gave alkane derivatives C8 and C10 by hydrogenation process followed by ring opening of furan in 15.2% yield. While, oxygenated product C10-C13 were also detected in 17.2% yield. The increasing of pore volume of 10NiAZ might enhance catalyst activity over H/D reaction. The alkene C=C bond was easy to hydrogenated under this condition by the lower bond energy gap.

D+D thermonuclear fusion reactions with polarized particles

International Nuclear Information System (INIS)

Kozma, P.

1986-01-01

Polarization measurements from the 2 H(d, n) 3 He and 2 H(d, p) 3 H thermonuclear reactions at deuteron energies below 1 MeV are anayzed. Results of analysis enable to discuss the existence of 4 He excited states in the vicinity of d+d threshold energy as well as to extrapolate total cross-sections σ tot (d+d) into the region of very low energies

A low temperature investigation of the gas-phase N(2D) + NO reaction. Towards a viable source of N(2D) atoms for kinetic studies in astrochemistry.

Science.gov (United States)

Nuñez-Reyes, Dianailys; Hickson, Kevin M

2018-06-18

The gas-phase reaction of metastable atomic nitrogen N(2D) with nitric oxide has been investigated over the 296-50 K temperature range using a supersonic flow reactor. As N(2D) could not be produced photolytically in the present work, these excited state atoms were generated instead through the C(3P) + NO → N(2D) + CO reaction while C(3P) atoms were created in situ by the 266 nm pulsed laser photolysis of CBr4 precursor molecules. The kinetics of N(2D) atoms were followed on-resonance by vacuum ultraviolet laser induced fluorescence at 116.7 nm. The measured rate constants for the N(2D) + NO reaction are in excellent agreement with most of the earlier work at room temperature and represent the only available kinetic data for this process below 296 K. The rate constants are seen to increase slightly as the temperature falls to 100 K with a more substantial increase at even lower temperature; a finding which is not reproduced by theoretical work. The prospects for using this chemical source of N(2D) atoms in future studies of a wide range of N(2D) atom reactions are discussed.

Kinetics of several oxygenated carbon-centered free radical reactions with NO2.

Science.gov (United States)

Rissanen, Matti P; Arppe, Suula L; Timonen, Raimo S

2013-05-16

Five oxygenated carbon-centered free radical reactions with nitrogen dioxide (NO2) have been studied in direct time-resolved measurements. Experiments were conducted in a temperature-controlled flow tube reactor coupled to a 193 nm exciplex laser photolysis and a resonance gas lamp photoionization mass spectrometer. Reactions were investigated under pseudofirst-order conditions, with the NO2 concentrations of the experiments in great excess over the initial radical concentrations ([R]0 CH3CO radical reactions with NO2 and, hence, includes the three smallest hydroxyalkyl radical species (CH2OH, CH2CH2OH, and CH3CHOH). The obtained rate coefficients are high with the temperature-dependent rate coefficients given by a formula k(T) = k300K × (T/300 K)(-n) as (in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO2) = (8.95 ± 2.70) × 10(-11) × (T/300 K)(-0.54±0.27) (T = 298-363 K), k(CH2CH2OH + NO2) = (5.99 ± 1.80) × 10(-11) × (T/300 K)(-1.49±0.45)(T = 241-363 K), k(CH3CHOH + NO2) = (7.48 ± 2.24) × 10(-11) × (T/300 K)(-1.36±0.41) (T = 266-363 K), k(CH3OCH2 + NO2) = (7.85 ± 2.36) × 10(-11) × (T/300 K)(-0.93±0.28) (T = 243-363 K), and k(CH3CO + NO2) = (2.87 ± 0.57) × 10(-11) × (T/300 K)(-2.45±0.49) (T = 241-363 K), where the uncertainties refer to the estimated overall uncertainties of the values obtained. The determined rate coefficients show negative temperature dependence with no apparent bath gas pressure dependence under the current experimental conditions (241-363 K and about 1-3 Torr helium). This behavior is typical for a radical-radical addition mechanism with no potential energy barrier above the energy of the separated reactants in the entrance channel of the reaction. Unfortunately the absence of detected product signals prevented gaining deeper insight into the reaction mechanism.

Tight-binding model of the photosystem II reaction center: application to two-dimensional electronic spectroscopy

International Nuclear Information System (INIS)

Gelzinis, Andrius; Valkunas, Leonas; Abramavicius, Darius; Fuller, Franklin D; Ogilvie, Jennifer P; Mukamel, Shaul

2013-01-01

We propose an optimized tight-binding electron–hole model of the photosystem II (PSII) reaction center (RC). Our model incorporates two charge separation pathways and spatial correlations of both static disorder and fast fluctuations of energy levels. It captures the main experimental features observed in time-resolved two-dimensional (2D) optical spectra at 77 K: peak pattern, lineshapes and time traces. Analysis of 2D spectra kinetics reveals that specific regions of the 2D spectra of the PSII RC are sensitive to the charge transfer states. We find that the energy disorder of two peripheral chlorophylls is four times larger than the other RC pigments. (paper)

Tight-binding model of the photosystem II reaction center: application to two-dimensional electronic spectroscopy

Science.gov (United States)

Gelzinis, Andrius; Valkunas, Leonas; Fuller, Franklin D.; Ogilvie, Jennifer P.; Mukamel, Shaul; Abramavicius, Darius

2013-07-01

We propose an optimized tight-binding electron-hole model of the photosystem II (PSII) reaction center (RC). Our model incorporates two charge separation pathways and spatial correlations of both static disorder and fast fluctuations of energy levels. It captures the main experimental features observed in time-resolved two-dimensional (2D) optical spectra at 77 K: peak pattern, lineshapes and time traces. Analysis of 2D spectra kinetics reveals that specific regions of the 2D spectra of the PSII RC are sensitive to the charge transfer states. We find that the energy disorder of two peripheral chlorophylls is four times larger than the other RC pigments.

The (3He,t) and (d,2He)reactions at intermediate energies

International Nuclear Information System (INIS)

Brockstedt, A.

1987-09-01

The ( 3 He,t) reaction has been studied at 0.6-2.3 GeV at small scattering angles, 0-7 degrees, on various nuclei ( 12 C, 13 C, 26 Mg, 40 Ca, 48 Ca, 54 Fe, 90 Zr, 159 Tb, 208 Pb) including a proton target. The reaction is a single-step reaction and selects the spin-isospin channel. Angular distributions for low-lying states in 12 N are well described by DWIA calculations. From 13 C to 13 N transitions the ratio J στ /J τ , at momentum transfer, q, close to zero, is derived. The ratio remains roughly constant in the region 300 - 700 MeV/nucleon. The position of the quasi-free peak is shifted compared with free nucleon-nucleon scattering. The shift is towards higher excitation energies at q approx 1.4 fm -1 , and towards lower excitation energies at q approx 2.5 fm -1 . The p( 3 He,t)Δ ++ reaction is analysed as one-pion exchange and the ( 3 He,t) form factor is extracted. The shape and position of the Δ resonance seem to be independent of target mass for the targets studied. Compared with the p to Δ ++ transition the position is shifted towards lower excitation energy in nuclei. The (d,2p[ 1 S 0 ]) reaction, with the two protons in an 1 S 0 state labelled 2 He, is studied at 0.65 and 2.0 GeV at small angles, 0-4 degrees, on some of the targets used in the ( 3 He,t) experiment (p, 12 C, 40 Ca, 54 Fe). This reaction is also a one-step reaction that can be used for studies of spin-isospin excitations. Cross sections and tensor analysing powers are determined for the p(d, 2 He)n reaction. These results are compared with PWIA calculations. The Δ resonance in carbon is also here shifted down in excitation energy compared with the proton target. (author)

Gamow-Teller matrix elements from the C-12(d,He-2) and Mg-24(d,He-2) reactions at 170 MeV

NARCIS (Netherlands)

Baumer, C; Frekers, D; Schmidt, R; van den Berg, AM; Hannen, VM; Harakeh, MN; de Huu, MA; Wörtche, HJ; De Frenne, D; Hagemann, M; Heyse, J; Jacobs, E; Fujita, Y

The Mg-24(d,He-2)Na-24 and the C-12(d,He-2)B-12 charge-exchange reactions have been studied at an incident energy of 170 MeV. The two protons in the S-1(0)(pp) state (indicated as He-2) were both momentum analyzed and detected by the same spectrometer and detector. Background-free He-2 spectra with

Theoretical Time Dependent Thermal Neutron Spectra and Reaction Rates in H2O and D2O

International Nuclear Information System (INIS)

Purohit, S.N.

1966-04-01

The early theoretical and experimental time dependent neutron thermalization studies were limited to the study of the transient spectrum in the diffusion period. The recent experimental measurements of the time dependent thermal neutron spectra and reaction rates, for a number of moderators, have generated considerable interest in the study of the time dependent Boltzmann equation. In this paper we present detailed results for the time dependent spectra and the reaction rates for resonance detectors using several scattering models of H 2 O and D 2 O. This study has been undertaken in order to interpret the integral time dependent neutron thermalization experiments in liquid moderators which have been performed at the AB Atomenergi. The proton gas and the deuteron gas models are inadequate to explain the measured reaction rates in H 2 O and D 2 O. The bound models of Nelkin for H 2 O and of Butler for D 2 O give much better agreement with the experimental results than the gas models. Nevertheless, some disagreement between theoretical and experimental results still persists. This study also indicates that the bound model of Butler and the effective mass 3. 6 gas model of Brown and St. John give almost identical reaction rates. It is also surprising to note that the calculated reaction rate for Cd for the Butler model appears to be in better agreement with the experimental results of D 2 O than of the Nelkin model with H 2 O experiments. The present reaction rate studies are sensitive enough so as to distinguish between the gas model and the bound model of a moderator. However, to investigate the details of a scattering law (such as the effect of the hindered rotations in H 2 O and D 2 O and the weights of different dynamical modes) with the help of these studies would require further theoretical as well as experimental investigations. Theoretical results can be further improved by improving the source for thermal neutrons, the group structure and the scattering

New determination of the 2H(d,p)3H and 2H(d,n)3He reaction rates at astrophysical energies

International Nuclear Information System (INIS)

Tumino, A.; Spartà, R.; Spitaleri, C.; Pizzone, R. G.; La Cognata, M.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Mukhamedzhanov, A. M.; Typel, S.; Tognelli, E.; Degl'Innocenti, S.; Prada Moroni, P. G.; Burjan, V.; Kroha, V.; Hons, Z.; Mrazek, J.; Piskor, S.; Lamia, L.

2014-01-01

The cross sections of the 2 H(d,p) 3 H and 2 H(d,n) 3 He reactions have been measured via the Trojan Horse method applied to the quasi-free 2 H( 3 He,p 3 H) 1 H and 2 H( 3 He,n 3 He) 1 H processes at 18 MeV off the proton in 3 He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the 2 H(d,n) 3 He reaction is quite influential on 7 Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (≤1 Myr) with masses ≥1 M ☉ .

Complete active space second order perturbation theory (CASPT2) study of N({sup 2}D) + H{sub 2}O reaction paths on D{sub 1} and D{sub 0} potential energy surfaces: Direct and roaming pathways

Energy Technology Data Exchange (ETDEWEB)

Isegawa, Miho; Liu, Fengyi [Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Kyoto 606-8103 (Japan); Maeda, Satoshi [Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Morokuma, Keiji, E-mail: morokuma@fukui.kyoto-u.ac.jp [Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Kyoto 606-8103 (Japan); Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322 (United States)

2014-10-21

We report reaction paths starting from N({sup 2}D) + H{sub 2}O for doublet spin states, D{sub 0} and D{sub 1}. The potential energy surfaces are explored in an automated fashion using the global reaction route mapping strategy. The critical points and reaction paths have been fully optimized at the complete active space second order perturbation theory level taking all valence electrons in the active space. In addition to direct dissociation pathways that would be dominant, three roaming processes, two roaming dissociation, and one roaming isomerization: (1) H{sub 2}ON → H–O(H)N → H–HON → NO({sup 2}Π) + H{sub 2}, (2) cis-HNOH → HNO–H → H–HNO → NO + H{sub 2}, (3) H{sub 2}NO → H–HNO → HNO–H → trans-HNOH, are confirmed on the D{sub 0} surface.

Measurement of astrophysical S-factors and electron screening potentials for d(d,n){sup 3}He reaction in ZrD{sub 2}, TiD{sub 2} and TaD{sub 0.5} targets in the ultralow energy region using plasma accelerator

Energy Technology Data Exchange (ETDEWEB)

Bystritsky, V.M., E-mail: bystvm@jinr.ru [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Bystritskii, Vit.M. [Department of Physics and Astronomy, University of California, Irvine (United States); Dudkin, G.N. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Filipowicz, M. [Faculty of Energy and Fuels, AGH, University of Science and Technology, Cracow (Poland); Gazi, S.; Huran, J. [Institute of Electrical Engineering, SAS, Bratislava (Slovakia); Kobzev, A.P. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Mesyats, G.A. [Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Nechaev, B.A.; Padalko, V.N. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Parzhitskii, S.S. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Pen' kov, F.M. [Institute of Nuclear Physics, NNC, Almaty (Kazakhstan); Philippov, A.V. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Kaminskii, V.L. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Tuleushev, Yu.Zh. [Institute of Nuclear Physics, NNC, Almaty (Kazakhstan); Wozniak, J. [Faculty of Physics and Applied Computer Sciences, AGH, University of Science and Technology, Cracow (Poland)

2012-09-01

The present paper is devoted to the study of the electron screening effect influence on the rate of d(d,n){sup 3}He reaction in the ultralow deuteron collision energy range in the deuterated metals (ZrD{sub 2}, TiD{sub 2} and TaD{sub 0.5}). The ZrD{sub 2}, TiD{sub 2} and TaD0.5 targets were fabricated via magnetron sputtering of titanium, zirconium and tantalum in gas (deuterium) environment. The experiments have been carried out using the high-current pulsed Hall plasma accelerator (NSR TPU, Russia). The detection of neutrons with energy of 2.5 MeV from the dd reaction was done with plastic scintillation spectrometers. As a result of the experiments, the energy dependences of the astrophysical S-factor for the dd reaction in the deuteron collision energy range of 2-7 keV and the values of the electron screening potential U{sub e} of the interacting deuterons have been measured for the above targets: U{sub e}(ZrD{sub 2})=(205{+-}35) eV; U{sub e}(TiD{sub 2})=(125{+-}34) eV; U{sub e}(TaD{sub 0.5})=(313{+-}58) eV. Our results are compared with the other published experimental and calculated data.

An Efficient Solid-phase Parallel Synthesis of 2-Amino and 2-Amidobenzo[d]oxazole Derivatives via Cyclization Reactions of 2-Hydroxyphenylthiourea Resin

International Nuclear Information System (INIS)

Jung, Selin; Kim, Seulgi; Lee, Geehyung; Gong, Youngdae

2012-01-01

An efficient solid-phase methodology has been developed for the synthesis of 2-amino and 2-amidobenzo[d]-oxazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo-[d]oxazole resins 4 by cyclization reaction of 2-hydroxyphenylthiourea resin 3. The resin-bound 2-hydroxy-phenylthiourea 3 is produced by the addition of 2-aminophenol to the isothiocyanate-terminated resin 2 and serve as a key intermediate for the linker resin. This core skeleton 2-aminobenzo[d]oxazole resin 4 undergoes functionalization reaction with various electrophiles, such as alkylhalides and acid chlorides to generate 2-amino and 2-amidobenzo[d]oxazole resins 5 and 6 respectively. Finally, 2-amino and 2-amidobenzo[d]oxazole derivatives 7 and 8 are then generated in good yields and purities by cleavage of the respective resins 5 and 6 under trifluoroacetic acid (TFA) in dichloromethane (CH 2 Cl 2 )

Spin-isospin excitation in sd-shell nuclei studied by the (d,2He) reaction at Ed=270MeV

International Nuclear Information System (INIS)

Niizeki, T.; Ohnuma, H.; Yamamoto, T.; Katoh, K.; Yamashita, T.; Hara, Y.; Okamura, H.; Sakai, H.; Ishida, S.; Sakamoto, N.; Otsu, H.; Wakasa, T.; Uesaka, T.; Satou, Y.; Fujita, T.; Ichihara, T.; Orihara, H.; Toyokawa, H.; Hatanaka, K.; Kato, S.; Kubono, S.; Yosoi, M.

1994-01-01

The (d, 2 He) reactions on 24 Mg, 26 Mg and 28 Si were studied at E d =270MeV. The 0 cross sections obtained for the 1 + states from the 24 Mg, 28 Si(d, 2 He) reactions show a good correlation with those from the mirror (p,n) reactions. Four peaks were identified in the 26 Mg(d, 2 He) 26 Ne reaction as being due to the 1 + excitation. The B(GT + ) values for these transitions were estimated and compared with the shell model prediction. ((orig.))

Mathematical Model of Synthesis Catalyst with Local Reaction Centers

Directory of Open Access Journals (Sweden)

I. V. Derevich

2017-01-01

Full Text Available The article considers a catalyst granule with a porous ceramic passive substrate and point active centers on which an exothermic synthesis reaction occurs. A rate of the chemical reaction depends on the temperature according to the Arrhenius law. Heat is removed from the pellet surface in products of synthesis due to heat transfer. In our work we first proposed a model for calculating the steady-state temperature of a catalyst pellet with local reaction centers. Calculation of active centers temperature is based on the idea of self-consistent field (mean-field theory. At first, it is considered that powers of the reaction heat release at the centers are known. On the basis of the found analytical solution, which describes temperature distribution inside the granule, the average temperature of the reaction centers is calculated, which then is inserted in the formula for heat release. The resulting system of transcendental algebraic equations is transformed into a system of ordinary differential equations of relaxation type and solved numerically to achieve a steady-state value. As a practical application, the article considers a Fischer-Tropsch synthesis catalyst granule with active cobalt metallic micro-particles. Cobalt micro-particles are the centers of the exothermic reaction of hydrocarbons macromolecular synthesis. Synthesis occurs as a result of absorption of the components of the synthesis gas on metallic cobalt. The temperature distribution inside the granule for a single local center and reaction centers located on the same granule diameter is found. It was found that there is a critical temperature of reactor exceeding of which leads to significant local overheating of the centers - thermal explosion. The temperature distribution with the local reaction centers is qualitatively different from the granule temperature, calculated in the homogeneous approximation. It is shown that, in contrast to the homogeneous approximation, the

The reactions of neutral iron clusters with D2O: Deconvolution of equilibrium constants from multiphoton processes

International Nuclear Information System (INIS)

Weiller, B.H.; Bechthold, P.S.; Parks, E.K.; Pobo, L.G.; Riley, S.J.

1989-01-01

The chemical reactions of neutral iron clusters with D 2 O are studied in a continuous flow tube reactor by molecular beam sampling and time-of-flight mass spectrometry with laser photoionization. Product distributions are invariant to a four-fold change in reaction time demonstrating that equilibrium is attained between free and adsorbed D 2 O. The observed negative temperature dependence is consistent with an exothermic, molecular addition reaction at equilibrium. Under our experimental conditions, there is significant photodesorption of D 2 O (Fe/sub n/(D 2 O)/sub m/ + hν → Fe/sub n/ + m D 2 O) along with ionization due to absorption of multiple photons from the ionizing laser. Using a simple model based on a rate equation analysis, we are able to quantitatively deconvolute this desorption process from the equilibrium constants. 8 refs., 1 fig

Vibrational state-resolved differential cross sections for the D + H2 → DH + H reaction

International Nuclear Information System (INIS)

Continetti, R.E.

1989-11-01

In this thesis, crossed-molecular-beams studies of the reaction D + H 2 → DH + H at collision energies of 0.53 and 1.01 eV are reported. Chapter 1 provides a survey of important experimental and theoretical studies on the dynamics of the hydrogen exchange reaction. Chapter 2 discusses the development of the excimer-laser photolysis D atom beam source that was used in these studies and preliminary experiments on the D + H 2 reaction. In Chapter 3, the differential cross section measurements are presented and compared to recent theoretical predictions. The measured differential cross sections for rotationally excited DH products showed significant deviations from recent quantum scattering calculations, in the first detailed comparison of experimental and theoretical differential cross sections. These results indicate that further work on the H 3 potential energy surface, particularly the bending potential, is in order

Excitation functions of the 98Mo+d reactions

International Nuclear Information System (INIS)

Zarubin, P.P.; Padalko, V.Yu.; Khrisanfov, Yu.V.; Lebedev, P.P.; Podkopaev, Yu.N.

The excitation functions of the 98 Mo+d reactions were studied. The energy dependence of (d,p),(d,n) and (d,α) reactions was investigated by the activation analysis. The energies of deuterons in the range (6-12) MeV were determined by means of the aluminium filters. 98 Mo foils with surface densities of 1.02, 0.23 and 0.14 mgxcm -2 with 98 Mo enrichment of 94.1% were used as targets. The gamma spectra were measured by a Ge(Li) detector. The 98 Mo(d,p) 99 Mo reaction excitation function was determined via detection of 739 and 181 keV γ-radiation of 99 Mo (Tsub(1/2)=66.47h); 140 keV γ-radiation of 99 Tc (Tsub(1/2)=6h) was detected for the 98 Mo(d,n) 99 Tc reaction excitation function determination and 460, 568, 1091, 1200 and 1492 keV γ-quanta of 96 Nb (Tsub(1/2)=23.35h) - for the 98 Mo(d,α) 96 Nb reaction. In the excitation function the wide extremum was observed at Esub(d) approximately 10 MeV. The ratio of cross sections σsup(m)(d,n)/σ(d,p) on the 98 Mo target was determined. The ratio σsup(m)(d,n)/σ(d,p) was found to be decreasing function of the deuteron energy. The relative cross sections were determined with an accuracy of +-5%, while for the absolute values of cross sections the accuracy was +-15%

Photosynthetic antennas and reaction centers: Current understanding and prospects for improvement

Energy Technology Data Exchange (ETDEWEB)

Blankenship, R.E. [Arizona State Univ., Tempe, AZ (United States)

1996-09-01

A brief introduction to the principles, structures and kinetic processes that take place in natural photosynthetic reaction center complexes is presented. Energy is first collected by an antenna system, and is transferred to a reaction center complex where primary electron transfer takes place. Secondary reactions lead to oxidation of water and reduction of CO{sub 2} in some classes of organisms. Antenna systems are highly regulated to maximize energy collection efficiency while avoiding photodamage. Some areas that are presently not well understood are listed.

An evolution from 3D face-centered-cubic ZnSnO3 nanocubes to 2D orthorhombic ZnSnO3 nanosheets with excellent gas sensing performance

International Nuclear Information System (INIS)

Chen Yuejiao; Yu Ling; Li Qing; Wu Yan; Li Qiuhong; Wang Taihong

2012-01-01

We have successfully observed the development of three-dimensional (3D) face-centered-cubic ZnSnO 3 into two-dimensional (2D) orthorhombic ZnSnO 3 nanosheets, which is the first observation of 2D ZnSnO 3 nanostructures to date. The synthesis from 3D to 2D nanostructures is realized by the dual-hydrolysis-assisted liquid precipitation reaction and subsequent hydrothermal treatment. The time-dependent morphology indicates the transformation via a ‘dissolution–recrystallization’ mechanism, accompanied by a ‘further growth’ process. Furthermore, the 2D ZnSnO 3 nanosheets consist of smaller sized nanoflakes. This further increases the special specific surface area and facilitates their application in gas sensing. The 2D ZnSnO 3 nanosheets exhibit excellent gas sensing properties, especially through their ultra-fast response and recovery. When exposed to ethanol and acetone, the response rate is as fast as 0.26 s and 0.18 s, respectively, and the concentration limit can reach as low as 50 ppb of ethanol. All these results are much better than those reported so far. Our experimental results indicate an efficient approach to realize high-performance gas sensors. (paper)

Energy transfer and reaction dynamics of matrix-isolated 1,2-difluoroethane-d4

Science.gov (United States)

Raff, Lionel M.

1990-09-01

The molecular dynamics of vibrationally excited 1,2-difluoroethane-d4 isolated in Ar, Kr, and Xe matrices at 12 K are investigated using trajectory methods. The matrix model is an fcc crystal containing 125 unit cells with 666 atoms in a cubic (5×5×5) arrangement. It is assumed that 1,2-difluoroethane-d4 is held interstitially within the volume bounded by the innermost unit cell of the crystal. The transport effects of the bulk are simulated using the velocity reset method introduced by Riley, Coltrin, and Diestler [J. Chem. Phys. 88, 5934 (1988)]. The system potential is written as the separable sum of a lattice potential, a lattice-molecule interaction and a gas-phase potential for 1,2-difluoroethane. The first two of these are assumed to have pairwise form while the molecular potential is a modified form of the global potential previously developed for 1,2-difluoroethane [J. Phys. Chem. 91, 3266 (1987)]. Calculated sublimation energies for the pure crystals are in good accord with the experimental data. The distribution of metastable-state energies for matrix-isolated 1,2-difluoroethane-d4 is Gaussian in form. In krypton, the full width at half maximum for the distribution is 0.37 eV. For a total excitation energy of 6.314 eV, the observed dynamic processes are vibrational relaxation, orientational exchange, and four-center DF elimination reactions. The first of these processes is characterized by a near linear, first-order decay curve with rate coefficients in the range 1.30-1.48×1011 s-1. The average rates in krypton and xenon are nearly equal. The process is slightly slower in argon. The decay curves exhibit characteristic high-frequency oscillations that are generally seen in energy transfer studies. It is demonstrated that these oscillations are associated with the frequencies for intramolecular energy transfer so that the entire frequency spectrum for such transfer processes can be obtained from the Fourier transform of the decay curve. Orientational

Molecular modeling and computational simulation of the photosystem-II reaction center to address isoproturon resistance in Phalaris minor.

Science.gov (United States)

Singh, Durg Vijay; Agarwal, Shikha; Kesharwani, Rajesh Kumar; Misra, Krishna

2012-08-01

Isoproturon is the only herbicide that can control Phalaris minor, a competitive weed of wheat that developed resistance in 1992. Resistance against isoproturon was reported to be due to a mutation in the psbA gene that encodes the isoproturon-binding D1 protein. Previously in our laboratory, a triazole derivative of isoproturon (TDI) was synthesized and found to be active against both susceptible and resistant biotypes at 0.5 kg/ha but has shown poor specificity. In the present study, both susceptible D1((S)), resistant D1((R)) and D2 proteins of the PS-II reaction center of P. minor have been modeled and simulated, selecting the crystal structure of PS-II from Thermosynechococcus elongatus (2AXT.pdb) as template. Loop regions were refined, and the complete reaction center D1/D2 was simulated with GROMACS in lipid (1-palmitoyl-2-oleoylglycero-3-phosphoglycerol, POPG) environment along with ligands and cofactor. Both S and R models were energy minimized using steepest decent equilibrated with isotropic pressure coupling and temperature coupling using a Berendsen protocol, and subjected to 1,000 ps of MD simulation. As a result of MD simulation, the best model obtained in lipid environment had five chlorophylls, two plastoquinones, two phenophytins and a bicarbonate ion along with cofactor Fe and oxygen evolving center (OEC). The triazole derivative of isoproturon was used as lead molecule for docking. The best worked out conformation of TDI was chosen for receptor-based de novo ligand design. In silico designed molecules were screened and, as a result, only those molecules that show higher docking and binding energies in comparison to isoproturon and its triazole derivative were proposed for synthesis in order to get more potent, non-resistant and more selective TDI analogs.

Energetic change of the primary quinone in photosynthetic reaction center. Mutation, delayed fluorescence and model calculations (Theses of the Ph.D. dissertation)

International Nuclear Information System (INIS)

Rinyu, L.

2007-01-01

Complete text of publication follows. Photosynthesis is one of the basic metabolic processes of living organisms. Photosynthesizing species (bacteria, algae and higher class plants) convert the energy of light into other forms of free energy (redox potential, electro- chemical potential of ions and protons and phosphate-potential) which are directly suit- able either to cover the energy need of the vital processes of the cell or to storage. In reaction center (RC) protein of photo- synthetic bacteria, electron transfer is initiated upon light excitation from the excited bacteriochlorophyll dimer (P) to the secondary quinone (Q B ) via bacteriopheophytine (Bph) and the primary quinone (Q A ). In Rhodobacter sphaeroides purple bacteria, both quinones are ubiquinone-10, but due to the different protein environment, their electrochemical properties is highly different. Whereas Q A makes one-electron chemistry, Q B can be doubly reduced to form hydroquinone, Q B H 2 by uptake of two protons. Q B H 2 subsequently leaves the RC and is replaced by an oxidized quinone from to membrane pool. The semiquinones are important intermediates in the quinone reduction cycle of the RC. The redox midpoint potentials of the Q/Q - redox pairs (E m ) are also different: the Q A /Q A - has 60 mV more negative potential than the Q B /Q B - couple (pH 8) to make the (interquinone) electron transfer favorable. For fine tuning of the midpoint redox potentials of the quinones, the protein assures appropriate steric and electrostatic environment. The most important aim of this study was the design and production of reaction center mutants in the binding pocket of the primary quinone to investigate the effect of the amino acids of the protein and lipids of the membrane on the thermodynamics of the primary quinone. The first priority was the determination of the absolute free energy gap between the P* and the P + Q A - states in wild type and mutant reaction centers by comparison of the

A single residue controls electron transfer gating in photosynthetic reaction centers

Czech Academy of Sciences Publication Activity Database

Shlyk, O.; Samish, I.; Matěnová, M.; Dulebo, A.; Poláková, H.; Kaftan, David; Scherz, A.

2017-01-01

Roč. 7, MAR 16 (2017), s. 1-13, č. článku 44580. ISSN 2045-2322 R&D Projects: GA ČR GA15-00703S; GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : BACTERIAL REACTION CENTERS * INDUCED STRUCTURAL-CHANGES * ATOMIC-FORCE MICROSCOPE Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.259, year: 2016

Rate coefficients from quantum and quasi-classical cumulative reaction probabilities for the S(1D) + H2 reaction

Science.gov (United States)

Jambrina, P. G.; Lara, Manuel; Menéndez, M.; Launay, J.-M.; Aoiz, F. J.

2012-10-01

Cumulative reaction probabilities (CRPs) at various total angular momenta have been calculated for the barrierless reaction S(1D) + H2 → SH + H at total energies up to 1.2 eV using three different theoretical approaches: time-independent quantum mechanics (QM), quasiclassical trajectories (QCT), and statistical quasiclassical trajectories (SQCT). The calculations have been carried out on the widely used potential energy surface (PES) by Ho et al. [J. Chem. Phys. 116, 4124 (2002), 10.1063/1.1431280] as well as on the recent PES developed by Song et al. [J. Phys. Chem. A 113, 9213 (2009), 10.1021/jp903790h]. The results show that the differences between these two PES are relatively minor and mostly related to the different topologies of the well. In addition, the agreement between the three theoretical methodologies is good, even for the highest total angular momenta and energies. In particular, the good accordance between the CRPs obtained with dynamical methods (QM and QCT) and the statistical model (SQCT) indicates that the reaction can be considered statistical in the whole range of energies in contrast with the findings for other prototypical barrierless reactions. In addition, total CRPs and rate coefficients in the range of 20-1000 K have been calculated using the QCT and SQCT methods and have been found somewhat smaller than the experimental total removal rates of S(1D).

Exchange reaction of acetylene-d2 with hydrogen chloride

International Nuclear Information System (INIS)

Bopp, A.F.; Kern, R.D.

1975-01-01

A mixture containing 3 percent each of the reactants C 2 D 2 and HCl in an Ne--Ar diluent was studied over the temperature range 1650 to 2600 0 K utilizing a shock tube coupled to a time-of-flight mass spectrometer. Plots of the mole fractions f of the exchange products, DCl and C 2 HD, revealed two distinct regions of growth: (a) an initial low conversion region characterized by an induction period t/sub i/; and (b) a region of accelerated exchange during which exchange products were formed with a quadratic dependence of the reaction time. These two regions labeled a and b were combined using two empirical equations, 1 - f/sub a//f/sub eq,a/ = exp [-k/sub a/[M]t], where t less than or equal to t/sub i/, and 1 - f/sub b//f/sub eq,b/ = exp [-k/sub b/[M](t - t/sub i/) 2 ], in order to represent the entire reaction profile at any given temperature within the interval investigated. The Arrhenius parameters for k/sub a/ and k/sub b/ were determined to be 10 11 . 15+-0 . 30 exp (-19990 +- 2850/RT) and 10 16 . 40+-0 . 41 exp (-31480 +- 4200/RT), respectively, for DCl and 10 11 . 69+-0 . 29 exp (-19150 +- 2740/RT) and 10 15 . 24+-0 . 34 exp (-17620 +- 3480/RT) for C 2 HD. The units for k/sub a/ are cm 3 mol -1 sec -1 and cm 3 mol -1 sec -2 for k/sub b/. Activation energies are reported in cal mol -1 . Comparison with the profiles obtained for acetylene pyrolysis strongly suggests that the mechanism for the exchange is atomic. Furthermore, the exchange experiments indicate that the initial step in the pyrolysis of acetylene is the disproportionation reaction, 2C 2 H 2 → C 2 H + C 2 H 3

Quantum-tunneling isotope-exchange reaction H2+D-→HD +H-

Science.gov (United States)

Yuen, Chi Hong; Ayouz, Mehdi; Endres, Eric S.; Lakhamanskaya, Olga; Wester, Roland; Kokoouline, Viatcheslav

2018-02-01

The tunneling reaction H2+D-→HD +H- was studied in a recent experimental work at low temperatures (10, 19, and 23 K) by Endres et al. [Phys. Rev. A 95, 022706 (2017), 10.1103/PhysRevA.95.022706]. An upper limit of the rate coefficient was found to be about 10-18cm3 /s. In the present study, reaction probabilities are determined using the ABC program developed by Skouteris et al. [Comput. Phys. Commun. 133, 128 (2000), 10.1016/S0010-4655(00)00167-3]. The probabilities for ortho-H2 and para-H2 in their ground rovibrational states are obtained numerically at collision energies above 50 meV with the total angular momentum J =0 -15 and extrapolated below 50 meV using a WKB approach. Thermally averaged rate coefficients for ortho- and para-H2 are obtained; the largest one, for ortho-H2, is about 3.1 ×10-20cm3 /s, which agrees with the experimental results.

Vibrational state-resolved differential cross sections for the D + H sub 2 yields DH + H reaction

Energy Technology Data Exchange (ETDEWEB)

Continetti, R.E.

1989-11-01

In this thesis, crossed-molecular-beams studies of the reaction D + H{sub 2} {yields} DH + H at collision energies of 0.53 and 1.01 eV are reported. Chapter 1 provides a survey of important experimental and theoretical studies on the dynamics of the hydrogen exchange reaction. Chapter 2 discusses the development of the excimer-laser photolysis D atom beam source that was used in these studies and preliminary experiments on the D + H{sub 2} reaction. In Chapter 3, the differential cross section measurements are presented and compared to recent theoretical predictions. The measured differential cross sections for rotationally excited DH products showed significant deviations from recent quantum scattering calculations, in the first detailed comparison of experimental and theoretical differential cross sections. These results indicate that further work on the H{sub 3} potential energy surface, particularly the bending potential, is in order.

Studies of the 198Hg(d,d') and 198Hg(d,p) reactions

Science.gov (United States)

Diaz Varela, Alejandra; Garrett, P. E.; Rand, E. T.; Ball, G. C.; Bilstein, V.; Laffoley, A. T.; Maclean, A. D.; Svensson, C. E.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

2017-09-01

Limits on the electric dipole moment (EDM) continue to decrease for 199Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for 199Hg is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. The E 3 and E 1 strength distributions to the ground state of 199Hg, and E 2 transitions amongst excited states, would be ideal information to further constrain 199Hg Schiff moment theoretical models. The high level density of 199Hg makes those determinations challenging, however the similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near 199Hg, two experiments, 198Hg(d,d') 198Hg and 198Hg(d,p)199Hg reaction were performed using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a 198Hg32S target. The (d,d') reaction allows us to probe the desired E 2 and E 3 matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of 199Hg.

Importance of d-wave contributions in the charge symmetry breaking reaction dd →4Heπ0

Science.gov (United States)

Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bondar, A.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Czerwiński, E.; Demmich, K.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W.; Fedorets, P.; Föhl, K.; Fransson, K.; Goldenbaum, F.; Goswami, A.; Grigoryev, K.; Gullström, C.-O.; Hanhart, C.; Heijkenskjöld, L.; Hejny, V.; Hüsken, N.; Jarczyk, L.; Johansson, T.; Kamys, B.; Kemmerling, G.; Khatri, G.; Khoukaz, A.; Khreptak, O.; Kirillov, D. A.; Kistryn, S.; Kleines, H.; Kłos, B.; Krzemień, W.; Kulessa, P.; Kupść, A.; Kuzmin, A.; Lalwani, K.; Lersch, D.; Lorentz, B.; Magiera, A.; Maier, R.; Marciniewski, P.; Mariański, B.; Morsch, H.-P.; Moskal, P.; Ohm, H.; Parol, W.; Perez del Rio, E.; Piskunov, N. M.; Prasuhn, D.; Pszczel, D.; Pysz, K.; Pyszniak, A.; Ritman, J.; Roy, A.; Rudy, Z.; Rundel, O.; Sawant, S.; Schadmand, S.; Schätti-Ozerianska, I.; Sefzick, T.; Serdyuk, V.; Shwartz, B.; Sitterberg, K.; Skorodko, T.; Skurzok, M.; Smyrski, J.; Sopov, V.; Stassen, R.; Stepaniak, J.; Stephan, E.; Sterzenbach, G.; Stockhorst, H.; Ströher, H.; Szczurek, A.; Trzciński, A.; Wolke, M.; Wrońska, A.; Wüstner, P.; Yamamoto, A.; Zabierowski, J.; Zieliński, M. J.; Złomańczuk, J.; Żuprański, P.; Żurek, M.; WASA-at-COSY Collaboration

2018-06-01

This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd →4Heπ0 using the WASA-at-COSY detector setup at an excess energy of Q = 60MeV. The determined differential cross section can be parametrized as d σ /d Ω = a + bcos2 ⁡θ*, where θ* is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a = (1.55 ± 0.46(stat) + 0.32 - 0.8 (syst)) pb /sr and b = (13.1 ± 2.1 (stat)-2.7+1.0 (syst)) pb /sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Δ isobar to the dd →4Heπ0 reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.

Mass-Producible 2D-MoS2-Impregnated Screen-Printed Electrodes That Demonstrate Efficient Electrocatalysis toward the Oxygen Reduction Reaction.

Science.gov (United States)

Rowley-Neale, Samuel J; Smith, Graham C; Banks, Craig E

2017-07-12

Two-dimensional molybdenum disulfide (2D-MoS 2 ) screen-printed electrodes (2D-MoS 2 -SPEs) have been designed, fabricated, and evaluated toward the electrochemical oxygen reduction reaction (ORR) within acidic aqueous media. A screen-printable ink has been developed that allows for the tailoring of the 2D-MoS 2 content/mass used in the fabrication of the 2D-MoS 2 -SPEs, which critically affects the observed ORR performance. In comparison to the graphite SPEs (G-SPEs), the 2D-MoS 2 -SPEs are shown to exhibit an electrocatalytic behavior toward the ORR which is found, critically, to be reliant upon the percentage mass incorporation of 2D-MoS 2 in the 2D-MoS 2 -SPEs; a greater percentage mass of 2D-MoS 2 incorporated into the 2D-MoS 2 -SPEs results in a significantly less electronegative ORR onset potential and a greater signal output (current density). Using optimally fabricated 2D-MoS 2 -SPEs, an ORR onset and a peak current of approximately +0.16 V [vs saturated calomel electrode (SCE)] and -1.62 mA cm -2 , respectively, are observed, which exceeds the -0.53 V (vs SCE) and -635 μA cm -2 performance of unmodified G-SPEs, indicating an electrocatalytic response toward the ORR utilizing the 2D-MoS 2 -SPEs. An investigation of the underlying electrochemical reaction mechanism of the ORR within acidic aqueous solutions reveals that the reaction proceeds via a direct four-electron process for all of the 2D-MoS 2 -SPE variants studied herein, where oxygen is electrochemically favorably reduced to water. The fabricated 2D-MoS 2 -SPEs are found to exhibit no degradation in the observed achievable current over the course of 1000 repeat scans. The production of such inks and the resultant mass-producible 2D-MoS 2 -SPEs mitigates the need to modify post hoc an electrode via the drop-casting technique that has been previously shown to result in a loss of achievable current over the course of 1000 repeat scans. The 2D-MoS 2 -SPEs designed, fabricated, and tested herein could

{sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions at sub-coulomb energies

Energy Technology Data Exchange (ETDEWEB)

Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Sparta, R.; Aliotta, M.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Mrazek, J.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L. [Universita degli Studi di Enna Kore, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); Cyclotron Institute Texas A and M University - College Station, Texas (United States); Excellence Cluster Universe - Technische Universitaet Muenchen, Garching, Germany and GSI Helmholtzzentrum fuer Schwerionenforschung GmbH - Theorie Darmstadt (Germany); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); School of Physics and Astronomy - University of Edinburgh, SUPA (United Kingdom); Nuclear Physics Institute of ASCR - Rez near Prague (Czech Republic); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); Nuclear Physics Institute of ASCR - Rez near Prague (Czech Republic); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy)

2012-11-20

The {sup 2}H({sup 3}He,p{sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n{sup 3}He){sup 1}H processes have been measured in quasi free kinematics to investigate for the first time the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions by means of the Trojan Horse Method. The {sup 3}He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

Theoretical Time Dependent Thermal Neutron Spectra and Reaction Rates in H{sub 2}O and D{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Purohit, S N

1966-04-15

The early theoretical and experimental time dependent neutron thermalization studies were limited to the study of the transient spectrum in the diffusion period. The recent experimental measurements of the time dependent thermal neutron spectra and reaction rates, for a number of moderators, have generated considerable interest in the study of the time dependent Boltzmann equation. In this paper we present detailed results for the time dependent spectra and the reaction rates for resonance detectors using several scattering models of H{sub 2}O and D{sub 2}O. This study has been undertaken in order to interpret the integral time dependent neutron thermalization experiments in liquid moderators which have been performed at the AB Atomenergi. The proton gas and the deuteron gas models are inadequate to explain the measured reaction rates in H{sub 2}O and D{sub 2}O. The bound models of Nelkin for H{sub 2}O and of Butler for D{sub 2}O give much better agreement with the experimental results than the gas models. Nevertheless, some disagreement between theoretical and experimental results still persists. This study also indicates that the bound model of Butler and the effective mass 3. 6 gas model of Brown and St. John give almost identical reaction rates. It is also surprising to note that the calculated reaction rate for Cd for the Butler model appears to be in better agreement with the experimental results of D{sub 2}O than of the Nelkin model with H{sub 2}O experiments. The present reaction rate studies are sensitive enough so as to distinguish between the gas model and the bound model of a moderator. However, to investigate the details of a scattering law (such as the effect of the hindered rotations in H{sub 2}O and D{sub 2}O and the weights of different dynamical modes) with the help of these studies would require further theoretical as well as experimental investigations. Theoretical results can be further improved by improving the source for thermal neutrons, the

Ab initio study of {sup 2}H(d,{gamma}){sup 4}He, {sup 2}H(d,p){sup 3}H, and {sup 2}H(d,n){sup 4}He reactions and the tensor force

Energy Technology Data Exchange (ETDEWEB)

Arai, K.; Aoyama, S.; Suzuki, Y.; Descouvemont, P.; Baye, D. [Division of General Education, Nagaoka National College of Technology, 888 Nishikatakai, Nagaoka, Niigata, 940-8532 (Japan); Center for Academic Information Service, Niigata University, Niigata 950-2181 (Japan); Department of Physics, Niigata University, Niigata 950-2181, Japan and RIKEN Nishina Center, Wako 351-0198 (Japan); Physique Nucleaire Theorique et Physique Mathematique, C.P.229, Universite Libre de Bruxelles, B 1050 Brussels (Belgium); Physique Quantique, CP165/82, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)

2012-11-12

The {sup 2}H(d,p){sup 3}H, {sup 2}H(d,n){sup 3}He, and {sup 2}H(d,{gamma}){sup 4}He reactions at low energies are studied with realistic nucleon-nucleon interactions in an ab initio approach. The obtained astrophysical S-factors are all in very good agreement with experiment. The most important channels for both transfer and radiative capture are all found to dominate thanks to the tensor force.

Requirements for charged-particle reaction cross sections in the d-d, d-t, t-t, and d-3He fuel cycles

International Nuclear Information System (INIS)

Jarmie, N.

1986-12-01

This paper reviews the status of experimental data and data evaluations for charged-particle reactions of interest in fusion-reactor design. In particular, the 2 H(t,α)n, 2 H(d,p) 3 H, 2 H(d, 3 He)n, 3 H(t,α)nn and 3 He(d,p) 4 He reactions at low energies are studied. Other secondary reactions are considered. The conclusion is that such cross sections are well known for the near and medium term, and that no crucial experimental lack exists. There is a serious lack of standard evaluations of these reactions, which should be in an internationally acceptable format and easily accessible. Support for generating such evaluations should be given serious consideration

Chemical reaction dynamics of Rydberg atoms with neutral molecules: A comparison of molecular-beam and classical trajectory results for the H(n)+D2→HD+D(n') reaction

International Nuclear Information System (INIS)

Song Hui; Dai Dongxu; Wu Guorong; Wang, C.-C.; Harich, Steven A.; Hayes, Michael Y.; Wang Xiuyan; Gerlich, Dieter; Yang Xueming; Skodje, Rex T.

2005-01-01

Recent molecular-beam experiments have probed the dynamics of the Rydberg-atom reaction, H(n)+D 2 →HD+D(n) at low collision energies. It was discovered that the rotationally resolved product distribution was remarkably similar to a much more limited data set obtained at a single scattering angle for the ion-molecule reaction H + +D 2 →D + +HD. The equivalence of these two problems would be consistent with the Fermi-independent-collider model (electron acting as a spectator) and would provide an important new avenue for the study of ion-molecule reactions. In this work, we employ a classical trajectory calculation on the ion-molecule reaction to facilitate a more extensive comparison between the two systems. The trajectory simulations tend to confirm the equivalence of the ion+molecule dynamics to that for the Rydberg-atom+molecule system. The theory reproduces the close relationship of the two experimental observations made previously. However, some differences between the Rydberg-atom experiments and the trajectory simulations are seen when comparisons are made to a broader data set. In particular, the angular distribution of the differential cross section exhibits more asymmetry in the experiment than in the theory. The potential breakdown of the classical model is discussed. The role of the 'spectator' Rydberg electron is addressed and several crucial issues for future theoretical work are brought out

Positronium formation and hydrated positron reactions in H2O, D2O, 1.74 M PPS/H2O and 1.74 M PPS/D2O solutions of Cl−, Br− and I−

DEFF Research Database (Denmark)

Mogensen, O. E.; Pedersen, Niels Jørgen

1986-01-01

Angular correlation of annihilation photons were measured for H2O, D2O, 1.74 M PPS/H2O and 1.74 M PPS/D2O solutions of Cl−, Br− and I−. The three components of the angular correlation spectra for D2O and H2O were nearly identical in shape. The positronium (Ps) yields for the H2O and D2O solutions...... before annihilation (lifetime 400 ps) was determined for the three halides in the four solvents. Simple kinetic equations (“trapping model”) with time dependent rate constant, solved analytically, could explain the [X−, e+] formation in H2O fairly well for concentrations below 0.03 M X−, if a diffusion...... controlled reaction with positron diffusion constant D = 5 × 10−5 cm2/s and reaction radius R = 1 nm were assumed. The three halides gave roughly identical [X−, e+] formation below 0.03 M X−. The difference between the four solutions could be explained partly only in terms of viscosity change for the model...

Neutron energy spectra of sup 2 sup 5 sup 2 Cf, Am-Be source and of the D(d,n) sup 3 He reaction

CERN Document Server

Sang Tae Park

2003-01-01

The neutron energy spectrum of the following sources were measured using a fast neutron spectrometer with the NE-213 liquid scintillator: sup 2 sup 5 sup 2 Cf, Am-Be and D(d,n) sup 3 He reaction from a 3 MeV Pelletron accelerator in Tokyo Institute of Technology. The measured proton recoil pulse height data of sup 2 sup 5 sup 2 Cf, Am-Be and D(d,n) sup 3 He were unfolded using the mathematical program to obtain the neutron energy spectrum. The sup 2 sup 5 sup 2 Cf and Am-Be neutron energy spectra were measured and the results obtained showed a good agreement with the spectra usually published in the literature. The neutron energy spectrum from D(d,n) sup 3 He was measured and the results obtained also showed a good agreement with the calculation by time of flight (TOF) methods. (author)

Exploring the dynamics of reaction N((2)D)+C2H4 with crossed molecular-beam experiments and quantum-chemical calculations.

Science.gov (United States)

Lee, Shih-Huang; Chin, Chih-Hao; Chen, Wei-Kan; Huang, Wen-Jian; Hsieh, Chu-Chun

2011-05-14

We conducted the title reaction using a crossed molecular-beam apparatus, quantum-chemical calculations, and RRKM calculations. Synchrotron radiation from an undulator served to ionize selectively reaction products by advantage of negligibly small dissociative ionization. We observed two products with gross formula C(2)H(3)N and C(2)H(2)N associated with loss of one and two hydrogen atoms, respectively. Measurements of kinetic-energy distributions, angular distributions, low-resolution photoionization spectra, and branching ratios of the two products were carried out. Furthermore, we evaluated total branching ratios of various exit channels using RRKM calculations based on the potential-energy surface of reaction N((2)D)+C(2)H(4) established with the method CCSD(T)/6-311+G(3df,2p)//B3LYP/6-311G(d,p)+ZPE[B3LYP/6-311G(d,p)]. The combination of experimental and computational results allows us to reveal the reaction dynamics. The N((2)D) atom adds to the C=C π-bond of ethene (C(2)H(4)) to form a cyclic complex c-CH(2)(N)CH(2) that directly ejects a hydrogen atom or rearranges to other intermediates followed by elimination of a hydrogen atom to produce C(2)H(3)N; c-CH(2)(N)CH+H is the dominant product channel. Subsequently, most C(2)H(3)N radicals, notably c-CH(2)(N)CH, further decompose to CH(2)CN+H. This work provides results and explanations different from the previous work of Balucani et al. [J. Phys. Chem. A, 2000, 104, 5655], indicating that selective photoionization with synchrotron radiation as an ionization source is a good choice in chemical dynamics research.

New determination of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reaction rates at astrophysical energies

Energy Technology Data Exchange (ETDEWEB)

Tumino, A.; Spartà, R.; Spitaleri, C.; Pizzone, R. G.; La Cognata, M.; Rapisarda, G. G.; Romano, S.; Sergi, M. L. [Laboratori Nazionali del Sud-INFN, Catania (Italy); Mukhamedzhanov, A. M. [Cyclotron Institute Texas A and M University-College Station, Texas (United States); Typel, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH-Theorie Darmstadt (Germany); Tognelli, E.; Degl' Innocenti, S.; Prada Moroni, P. G. [Dipartimento di Fisica, Università di Pisa, and INFN-Sezione di Pisa, Pisa (Italy); Burjan, V.; Kroha, V.; Hons, Z.; Mrazek, J.; Piskor, S. [Nuclear Physics Institute of ASCR-Rez near Prague (Czech Republic); Lamia, L., E-mail: tumino@lns.infn.it [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania (Italy)

2014-04-20

The cross sections of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured via the Trojan Horse method applied to the quasi-free {sup 2}H({sup 3}He,p {sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n {sup 3}He){sup 1}H processes at 18 MeV off the proton in {sup 3}He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the {sup 2}H(d,n){sup 3}He reaction is quite influential on {sup 7}Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (≤1 Myr) with masses ≥1 M {sub ☉}.

The reaction d(α,γ)6Li at low energies and the primordial nucleosynthesis of 6Li

International Nuclear Information System (INIS)

Cecil, F.E.; Yan, J.; Galovich, C.S.

1996-01-01

We have searched for the reaction d(α,γ) 6 Li at an α-d center-of-mass energy of 53 keV. An upper limit on the reaction S factor is 2.0x10 -7 MeVb at the 90% confidence level, corresponding to a limit on the synthesis of 6 Li from a standard big bang of 0.9% of the present abundance for a total baryon-to-photon ratio 2.86 10 6 Li-to- 7 Li isotopic abundance ratio immediately after a standard big bang is constrained to be less than 0.85%, considerably less than a recent measurement of this ratio in a metal-poor, Population II halo star. copyright 1996 The American Physical Society

Reactions of State-Selected Atomic Oxygen Ions O+(S-4, D-2, P-2) with Methane

Czech Academy of Sciences Publication Activity Database

de Miranda, B. C.; Romanzin, C.; Chefdeville, M.; Vuitton, V.; Žabka, Ján; Polášek, Miroslav; Alcaraz, C.

2015-01-01

Roč. 119, č. 23 (2015), s. 6082-6098 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA14-19693S; GA MŠk(CZ) LD14024 Institutional support: RVO:61388955 Keywords : CHARGE-TRANSFER REACTIONS * PHOTOELECTRON-PHOTOION COINCIDENCE * TRANSLATIONAL ENERGY-DEPENDENCE Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.883, year: 2015

WE-AB-BRA-07: Quantitative Evaluation of 2D-2D and 2D-3D Image Guided Radiation Therapy for Clinical Trial Credentialing, NRG Oncology/RTOG

Energy Technology Data Exchange (ETDEWEB)

Giaddui, T; Yu, J; Xiao, Y [Thomas Jefferson University, Philadelphia, PA (United States); Jacobs, P [MIM Software, Inc, Cleavland, Ohio (United States); Manfredi, D; Linnemann, N [IROC Philadelphia, RTQA Center, Philadelphia, PA (United States)

2015-06-15

Purpose: 2D-2D kV image guided radiation therapy (IGRT) credentialing evaluation for clinical trial qualification was historically qualitative through submitting screen captures of the fusion process. However, as quantitative DICOM 2D-2D and 2D-3D image registration tools are implemented in clinical practice for better precision, especially in centers that treat patients with protons, better IGRT credentialing techniques are needed. The aim of this work is to establish methodologies for quantitatively reviewing IGRT submissions based on DICOM 2D-2D and 2D-3D image registration and to test the methodologies in reviewing 2D-2D and 2D-3D IGRT submissions for RTOG/NRG Oncology clinical trials qualifications. Methods: DICOM 2D-2D and 2D-3D automated and manual image registration have been tested using the Harmony tool in MIM software. 2D kV orthogonal portal images are fused with the reference digital reconstructed radiographs (DRR) in the 2D-2D registration while the 2D portal images are fused with DICOM planning CT image in the 2D-3D registration. The Harmony tool allows alignment of the two images used in the registration process and also calculates the required shifts. Shifts calculated using MIM are compared with those submitted by institutions for IGRT credentialing. Reported shifts are considered to be acceptable if differences are less than 3mm. Results: Several tests have been performed on the 2D-2D and 2D-3D registration. The results indicated good agreement between submitted and calculated shifts. A workflow for reviewing these IGRT submissions has been developed and will eventually be used to review IGRT submissions. Conclusion: The IROC Philadelphia RTQA center has developed and tested a new workflow for reviewing DICOM 2D-2D and 2D-3D IGRT credentialing submissions made by different cancer clinical centers, especially proton centers. NRG Center for Innovation in Radiation Oncology (CIRO) and IROC RTQA center continue their collaborative efforts to enhance

WE-AB-BRA-07: Quantitative Evaluation of 2D-2D and 2D-3D Image Guided Radiation Therapy for Clinical Trial Credentialing, NRG Oncology/RTOG

International Nuclear Information System (INIS)

Giaddui, T; Yu, J; Xiao, Y; Jacobs, P; Manfredi, D; Linnemann, N

2015-01-01

Purpose: 2D-2D kV image guided radiation therapy (IGRT) credentialing evaluation for clinical trial qualification was historically qualitative through submitting screen captures of the fusion process. However, as quantitative DICOM 2D-2D and 2D-3D image registration tools are implemented in clinical practice for better precision, especially in centers that treat patients with protons, better IGRT credentialing techniques are needed. The aim of this work is to establish methodologies for quantitatively reviewing IGRT submissions based on DICOM 2D-2D and 2D-3D image registration and to test the methodologies in reviewing 2D-2D and 2D-3D IGRT submissions for RTOG/NRG Oncology clinical trials qualifications. Methods: DICOM 2D-2D and 2D-3D automated and manual image registration have been tested using the Harmony tool in MIM software. 2D kV orthogonal portal images are fused with the reference digital reconstructed radiographs (DRR) in the 2D-2D registration while the 2D portal images are fused with DICOM planning CT image in the 2D-3D registration. The Harmony tool allows alignment of the two images used in the registration process and also calculates the required shifts. Shifts calculated using MIM are compared with those submitted by institutions for IGRT credentialing. Reported shifts are considered to be acceptable if differences are less than 3mm. Results: Several tests have been performed on the 2D-2D and 2D-3D registration. The results indicated good agreement between submitted and calculated shifts. A workflow for reviewing these IGRT submissions has been developed and will eventually be used to review IGRT submissions. Conclusion: The IROC Philadelphia RTQA center has developed and tested a new workflow for reviewing DICOM 2D-2D and 2D-3D IGRT credentialing submissions made by different cancer clinical centers, especially proton centers. NRG Center for Innovation in Radiation Oncology (CIRO) and IROC RTQA center continue their collaborative efforts to enhance

Trojan Horse particle invariance for 2H(d,p)3H reaction: a detailed study

International Nuclear Information System (INIS)

Pizzone, R.G.; La Cognata, M.; Rinollo, A.; Spitaleri, C; Sparta, R.; Bertulani, C.A.; Mukhamedzhanov, A.M.; Blokhintsev, L.; Lamia, L.; Tumino, A.

2014-01-01

The basic idea of the Trojan Horse Method (THM) is to extract the cross section in the low-energy region of a two-body reaction with significant astrophysical impact: a + x → c + C from a suitable quasi-free (QF) break-up of the so called Trojan Horse nucleus, e.g. A=x (+) s where usually x is referred to as the participant and s as the spectator particle. In the last decades the Trojan Horse method has played a crucial role for the measurement of several charged particle induced reactions cross sections of astrophysical interest. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was therefore tested using the quasi free 2 H( 6 Li, pt) 4 He and 2 H( 3 He,pt)H reactions after 6 Li and 3 He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. Polynomial fits were then performed on the data giving S 0 = (75 ± 21) keV*b in the case of the 6 Li break-up, while for 3 He one obtains S 0 = (58 ± 2) keV*b. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the plane wave approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case

Resident Reactions to Person-Centered Communication by Long-Term Care Staff.

Science.gov (United States)

Savundranayagam, Marie Y; Sibalija, Jovana; Scotchmer, Emma

2016-09-01

Long-term care staff caregivers who are person centered incorporate the life history, preferences, and feelings of residents with dementia during care interactions. Communication is essential for person-centered care. However, little is known about residents' verbal reactions when staff use person-centered communication. Accordingly, this study investigated the impact of person-centered communication and missed opportunities for such communication by staff on resident reactions. Conversations (N = 46) between staff-resident dyads were audio-recorded during routine care tasks over 12 weeks. Staff utterances were coded for person-centered communication and missed opportunities. Resident utterances were coded for positive reactions, such as cooperation, and negative reactions, such as distress. Linear regression analyses revealed that the more staff used person-centered communication, the more likely that residents reacted positively. Additionally, the more missed opportunities in a conversation, the more likely that the residents reacted negatively. Conversation illustrations elaborate on the quantitative findings and implications for staff training are discussed. © The Author(s) 2016.

1H(d,2p)n reaction at 2 GeV deuteron energy

International Nuclear Information System (INIS)

Erohuml, J.; Fodor, Z.; Koncz, P.; Seres, Z.; Perdrisat, C.F.; Punjabi, V.; Boudard, A.; Bonin, B.; Garcon, M.; Lombard, R.; Mayer, B.; Terrien, Y.; Tomasi, E.; Boivin, M.; Yonnet, J.; Bhang, H.C.; Youn, M.; Belostotsky, S.L.; Grebenuk, O.G.; Nikulin, V.N.; Kudin, L.G.

1994-01-01

The 1 H(d,2p)n deuteron breakup reaction was measured at 2 GeV deuteron energy in a kinematically complete experiment. Fivefold differential cross sections are given in a wide range of kinematical variables and analyzed in terms of impulse approximation and NN rescattering. The deuteron momentum density was determined and deviations were found depending on the value of the four-momentum transfer |t| in the scattering process. At low |t| the momentum densities are in good agreement with the impulse approximation whereas large discrepancies were found above q∼200 MeV/c when the four-momentum transfer was large. Various possible origins of the anomalous behavior at high q values are discussed

Forward absolute cross-section of the reaction 2H(d,n)3He for Esub(d) = (3/6)MeV

International Nuclear Information System (INIS)

Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.; Galeazzi, G.

1981-01-01

The zero-degree differential cross-section of the reaction 2 H(d,n) 3 He was measured, by means of a recoil-proton neutron counter telescope, with an accuracy of 2%, in the incident-deuteron energy interval from 3 to 6 MeV. (author)

The energy spectrum of neutrons from 7Li(d,n)8Be reaction at deuteron energy 2.9 MeV

Science.gov (United States)

Mitrofanov, Konstantin V.; Piksaikin, Vladimir M.; Zolotarev, Konstantin I.; Egorov, Andrey S.; Gremyachkin, Dmitrii E.

2017-09-01

The neutron beams generated at the electrostatic accelerators using nuclear reactions T(p,n)3He, D(d,n)3He, 7Li(p,n)7Be, T(d,n)4He, 7Li(d,n)8Be, 9Be(d,n)10B are widely used in neutron physics and in many practical applications. Among these reactions the least studied reactions are 7Li(d,n)8Be and 9Be(d,n)10B. The present work is devoted to the measurement of the neutron spectrum from 7Li(d,n)8Be reaction at 0∘ angle to the deuteron beam axis on the electrostatic accelerator Tandetron (JSC "SSC RF - IPPE") using activation method and a stilbene crystal scintillation detector. The first time ever 7Li(d,n)8Be reaction was measured by activation method. The target was a thick lithium layer on metallic backing. The energy of the incident deuteron was 2.9 MeV. As activation detectors a wide range of nuclear reactions were used: 27Al(n,p)27Mg, 27Al(n,α)24Na, 113In(n,n')113mIn, 115In(n,n')115mIn, 115In(n,γ)116mIn, 58Ni(n,p)58mCo, 58Ni(n,2n)57Ni, 197Au(n,γ)198Au, 197Au(n,2n)196Au, 59Co(n,p)59Fe, 59Co(n,2n)58m+gCo, 59Co (n,g)60Co. Measurement of the induced gamma-activity was carried out using HPGe detector Canberra GX5019 [1]. The up-to-date evaluations of the cross sections for these reactions were used in processing of the data. The program STAYSL was used to unfold the energy spectra. The neutron spectra obtained by activation detectors is consistent with the corresponding data measured by a stilbene crystal scintillation detector within their uncertainties.

The energy spectrum of neutrons from 7Li(d,n8Be reaction at deuteron energy 2.9 MeV

Directory of Open Access Journals (Sweden)

Mitrofanov Konstantin V.

2017-01-01

Full Text Available The neutron beams generated at the electrostatic accelerators using nuclear reactions T(p,n3He, D(d,n3He, 7Li(p,n7Be, T(d,n4He, 7Li(d,n8Be, 9Be(d,n10B are widely used in neutron physics and in many practical applications. Among these reactions the least studied reactions are 7Li(d,n8Be and 9Be(d,n10B. The present work is devoted to the measurement of the neutron spectrum from 7Li(d,n8Be reaction at 0∘ angle to the deuteron beam axis on the electrostatic accelerator Tandetron (JSC “SSC RF – IPPE” using activation method and a stilbene crystal scintillation detector. The first time ever 7Li(d,n8Be reaction was measured by activation method. The target was a thick lithium layer on metallic backing. The energy of the incident deuteron was 2.9 MeV. As activation detectors a wide range of nuclear reactions were used: 27Al(n,p27Mg, 27Al(n,α24Na, 113In(n,n'113mIn, 115In(n,n'115mIn, 115In(n,γ116mIn, 58Ni(n,p58mCo, 58Ni(n,2n57Ni, 197Au(n,γ198Au, 197Au(n,2n196Au, 59Co(n,p59Fe, 59Co(n,2n58m+gCo, 59Co (n,g60Co. Measurement of the induced gamma-activity was carried out using HPGe detector Canberra GX5019 [1]. The up-to-date evaluations of the cross sections for these reactions were used in processing of the data. The program STAYSL was used to unfold the energy spectra. The neutron spectra obtained by activation detectors is consistent with the corresponding data measured by a stilbene crystal scintillation detector within their uncertainties.

How exciton-vibrational coherences control charge separation in the photosystem II reaction center.

Science.gov (United States)

Novoderezhkin, Vladimir I; Romero, Elisabet; van Grondelle, Rienk

2015-12-14

In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.

Reaction of Br/sub 3/. /sup 2 -/ with 2-deoxy-D-ribose. A preferred attack at C-1

Energy Technology Data Exchange (ETDEWEB)

Parsons, B J; Schulte-Frohlinde, D; von Sonntag, C [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany, F.R.). Inst. fuer Strahlenchemie

1978-06-01

In the photolysis of 5-bromouracil containing DNA Br atoms are expected intermediates. In order to evaluate the possible site of attack of the Br atom at the sugar moiety of DNA the reaction of 2-deoxy-D-Ribose with the Br atom (complexed with two bromide ions) was investigated. Hydroxyl radicals generated by the radiolysis of N/sub 2/O saturated aqueous solutions were converted into Br/sub 3/./sup 2 -/-radicals by 1 M bromide ions. Br/sub 3/./sup 2 -/-reacts with 2-deoxy-D-ribose (k = 3.7 x 10/sup 4/M/sup -1/s/sup -1/, pulse radiolysis). The major product is 2-deoxy-D-erythro-pentonic acid (G = 2.4, ..gamma..-radiolysis). It is formed by hydrogen abstraction from C-1 and oxidation of this radical by other radicals. An alternative route via the radical at C-2 is neglible. It follows that Br/sub 3/./sup 2 -/ reacts preferentially at C-1 of 2-deoxy-D-ribose.

New Determination of the H-2(d,p)H-3 and H-2(d,n)He-3 Reaction Rates at Astrophysical Energies

Czech Academy of Sciences Publication Activity Database

Tumino, A.; Sparta, R.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Pizzone, R. G.; Tognelli, E.; Degl'Innocenti, S.; Burjan, Václav; Kroha, Václav; Hons, Zdeněk; La Cognata, M.; Lamia, L.; Mrázek, Jaromír; Piskoř, Štěpán; Moroni, P. G. P.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

2014-01-01

Roč. 785, č. 2 (2014), s. 96 ISSN 0004-637X R&D Projects: GA MŠk LC07050; GA ČR GAP203/10/0310 Institutional support: RVO:61389005 Keywords : nuclear reactions * nucleosynthesis * abundances * primordial nucleosynthesis * stars: pre-main sequence Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 5.993, year: 2014

Addition reaction of adamantylideneadamantane with Br2 and 2Br2: a computational study.

Science.gov (United States)

Islam, Shahidul M; Poirier, Raymond A

2008-01-10

Ab initio calculations were carried out for the reaction of adamantylideneadamantane (Ad=Ad) with Br2 and 2Br2. Geometries of the reactants, transition states, intermediates, and products were optimized at HF and B3LYP levels of theory using the 6-31G(d) basis set. Energies were also obtained using single point calculations at the MP2/6-31G(d)//HF/6-31G(d), MP2/6-31G(d)//B3LYP/6-31G(d), and B3LYP/6-31+G(d)//B3LYP/6-31G(d) levels of theory. Intrinsic reaction coordinate (IRC) calculations were performed to characterize the transition states on the potential energy surface. Only one pathway was found for the reaction of Ad=Ad with one Br2 producing a bromonium/bromide ion pair. Three mechanisms for the reaction of Ad=Ad with 2Br2 were found, leading to three different structural forms of the bromonium/Br3- ion pair. Activation energies, free energies, and enthalpies of activation along with the relative stability of products for each reaction pathway were calculated. The reaction of Ad=Ad with 2Br2 was strongly favored over the reaction with only one Br2. According to B3LYP/6-31G(d) and single point calculations at MP2, the most stable bromonium/Br3- ion pair would form spontaneously. The most stable of the three bromonium/Br3- ion pairs has a structure very similar to the observed X-ray structure. Free energies of activation and relative stabilities of reactants and products in CCl4 and CH2ClCH2Cl were also calculated with PCM using the united atom (UA0) cavity model and, in general, results similar to the gas phase were obtained. An optimized structure for the trans-1,2-dibromo product was also found at all levels of theory both in gas phase and in solution, but no transition state leading to the trans-1,2-dibromo product was obtained.

Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

Science.gov (United States)

Al-Rubaiey, Najem A.; Walsh, Robin

2017-03-01

Silylenes (silanediyls) have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD) of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2) are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas) at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using Lindemann

Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

Directory of Open Access Journals (Sweden)

Al-Rubaiey Najem A.

2017-01-01

Full Text Available Silylenes (silanediyls have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2 are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using

Magnitude and direction of the change in dipole moment associated with excitation of the primary electron donor in Rhodopseudomonas sphaeroides reaction centers

Energy Technology Data Exchange (ETDEWEB)

Lockhart, D.J.; Boxer, S.G.

1987-02-10

The magnitude and direction of the change in dipole moment, ..delta mu.., associated with the Q/sub y/ transition of the dimeric primary electron donor (special pair or P870) in Rhodopseudomonas sphaeroides reaction centers have been measured by Stark spectroscopy at 20 /sup 0/C. The magnitude of ..delta mu.. is found to be f/sup -1/ (10.3 +/- 0.7) D, where f is a correction factor for the local dielectric properties of the protein matrix. With the spherical cavity approximation and an effective local dielectric constant of 2, f = 1.2, and absolute value of ..delta mu.. is 8.6 +/- 0.6 D. Absolute value of ..delta mu.. for the Q/sub y/ transition of the special pair is approximately a factor of 3.4 and 2 greater than for the monomeric bacteriochlorophylls and bacteriopheophytins, respectively, in the reaction center. The angle between ..delta mu.. and the transition dipole moment for excitation of the first singlet electron state of the special pair was found to be 24 +/- 2/sup 0/. The measured values are combined to suggest a physical model in which the lowest excited singlet state of the special pair has substantial charge-transfer character and where charge is separated between the two monomers comprising the dimeric special pair. This leads to the hypothesis that the first charge-separated state in bacterial photosynthesis is formed directly upon photoexcitation. These data provide stringent values for comparison with theoretical calculations of the electronic structure of the chromophores in the reaction center.

2D nanosheet molybdenum disulphide (MoS2) modified electrodes explored towards the hydrogen evolution reaction

Science.gov (United States)

Rowley-Neale, Samuel J.; Brownson, Dale A. C.; Smith, Graham C.; Sawtell, David A. G.; Kelly, Peter J.; Banks, Craig E.

2015-10-01

We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER.We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode

Designing an Epithermal Neutron Beam for Boron Neutron Capture Therapy for the Fusion Reactions 2H(d,n)3He and 3H(d,n)4He1

International Nuclear Information System (INIS)

Verbeke, J.M.; Costes, S.V.; Bleuel, D.; Vujic, J.; Leung, K.N.

1998-01-01

A beam shaping assembly has been designed to moderate high energy neutrons from the fusion reactions 2 H(d,N) 3 He and 3 H(d,n) 4 He for use fin boron neutron capture therapy. The low neutron yield of the 2 H(d,n) 3 He reaction led to unacceptably long treatment times. However, a 160 mA deuteron beam of energy 400 keV led to a treatment time of 120 minutes with the reaction 3 H(d,n) 4 He. Equivalent doses of 9.6 Gy-Eq and 21.9 Gy-Eq to the skin and to a 8 cm deep tumor respectively have been computed

Bare nucleus S(E) factor of the 2H(d,p)3H and 2H(d,n)3He reactions via the Trojan Horse Method

International Nuclear Information System (INIS)

Tumino, A; Spitaleri, C; Kiss, G G; Cognata, M La; Lamia, L; Pizzone, R G; Rapisarda, G G; Romano, S; Sergi, M L; Spartà, R; Mukhamedzhanov, A M; Typel, S; Aliotta, M; Burjan, V; Kroha, V; Hons, Z; Mrazek, J; Piskor, S; Santo, M Gimenez del

2012-01-01

The Trojan Horse Method was applied for the first time to the 2 H(d,p) 3 H and 2 H(d,n) 3 He reactions by measuring the 2 H( 3 He,p 3 H) 1 H and 2 H( 3 He,n 3 He) 1 H processes in quasi free kinematics. The 3 He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4±1.8 MeVb for 3 H+p and 60.1±1.9 MeVb for 3 He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

Functional type 2 photosynthetic reaction centers found in the rare bacterial phylum Gemmatimonadetes

OpenAIRE

Zeng, Yonghui; Feng, Fuying; Medová, Hana; Dean, Jason; Koblížek, Michal

2014-01-01

Photosynthesis is one of the most fundamental biological processes on Earth. To date, species capable of performing (bacterio)chlorophyll-based phototrophy have been reported in six bacterial phyla. Here we report a phototrophic bacterium belonging to the rare and understudied phylum Gemmatimonadetes. This strain, isolated from a freshwater lake in the Gobi Desert, contains fully functional photosynthetic reaction centers. Its photosynthesis genes appear to originate from an ancient horizonta...

Conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center

DEFF Research Database (Denmark)

Katona, Gergely; Snijder, Arjan; Gourdon, Pontus Emanuel

2005-01-01

In bright light the photosynthetic reaction center (RC) of Rhodobacter sphaeroides stabilizes the P(+)(870).Q(-)(A) charge-separated state and thereby minimizes the potentially harmful effects of light saturation. Using X-ray diffraction we report a conformational change that occurs within the cy...... the cytoplasmic domain of this RC in response to prolonged illumination with bright light. Our observations suggest a novel structural mechanism for the regulation of electron transfer reactions in photosynthesis....

Vasovagal reactions in whole blood donors at 3 REDS-II blood centers in Brazil

Science.gov (United States)

Goncalez, T. T.; Sabino, E. C.; Schlumpf, K.S.; Wright, D.J.; Leao, S.; Sampaio, D.; Takecian, P. L.; Carneiro-Proietti, AB; Murphy, E.; Busch, M.; Custer, B.

2013-01-01

Background In Brazil little is known about adverse reactions during donation and the donor characteristics that may be associated with such events. Donors are offered snacks and fluids prior to donating and are required to consume a light meal after donation. For these reasons the frequency of reactions may be different than those observed in other countries. Methods A cross-sectional study was conducted of eligible whole blood donors at three large blood centers located in Brazil between July 2007 and December 2009. Vasovagal reactions (VVRs) along with donor demographic and biometric data were collected. Reactions were defined as any presyncopal or syncopal event during the donation process. Multivariable logistic regression was performed to identify predictors of VVRs. Results Of 724,861 donor presentations, 16,129 (2.2%) VVRs were recorded. Rates varied substantially between the three centers: 53, 290 and 381 per 10,000 donations in Recife, São Paulo and Belo Horizonte, respectively. Although the reaction rates varied, the donor characteristics associated with VVRs were similar [younger age (18–29), replacement donors, first time donors, low estimated blood volume (EBV)]. In multivariable analysis controlling for differences between the donor populations in each city younger age, first-time donor status and lower EBV were the factors most associated with reactions. Conclusion Factors associated with VVRs in other locations are also evident in Brazil. The difference in VVR rates between the three centers might be due to different procedures for identifying and reporting the reactions. Potential interventions to reduce the risk of reactions in Brazil should be considered. PMID:22073941

Controlled nitric oxide production via O(1D) + N2O reactions for use in oxidation flow reactor studies

Science.gov (United States)

Lambe, Andrew; Massoli, Paola; Zhang, Xuan; Canagaratna, Manjula; Nowak, John; Daube, Conner; Yan, Chao; Nie, Wei; Onasch, Timothy; Jayne, John; Kolb, Charles; Davidovits, Paul; Worsnop, Douglas; Brune, William

2017-06-01

Oxidation flow reactors that use low-pressure mercury lamps to produce hydroxyl (OH) radicals are an emerging technique for studying the oxidative aging of organic aerosols. Here, ozone (O3) is photolyzed at 254 nm to produce O(1D) radicals, which react with water vapor to produce OH. However, the need to use parts-per-million levels of O3 hinders the ability of oxidation flow reactors to simulate NOx-dependent secondary organic aerosol (SOA) formation pathways. Simple addition of nitric oxide (NO) results in fast conversion of NOx (NO + NO2) to nitric acid (HNO3), making it impossible to sustain NOx at levels that are sufficient to compete with hydroperoxy (HO2) radicals as a sink for organic peroxy (RO2) radicals. We developed a new method that is well suited to the characterization of NOx-dependent SOA formation pathways in oxidation flow reactors. NO and NO2 are produced via the reaction O(1D) + N2O → 2NO, followed by the reaction NO + O3 → NO2 + O2. Laboratory measurements coupled with photochemical model simulations suggest that O(1D) + N2O reactions can be used to systematically vary the relative branching ratio of RO2 + NO reactions relative to RO2 + HO2 and/or RO2 + RO2 reactions over a range of conditions relevant to atmospheric SOA formation. We demonstrate proof of concept using high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) measurements with nitrate (NO3-) reagent ion to detect gas-phase oxidation products of isoprene and α-pinene previously observed in NOx-influenced environments and in laboratory chamber experiments.

Isotope effects of reactions in quantum solids initiated by IR + UV lasers: quantum model simulations for Cl((2)P(3/2)) + X(2)(ν) → XCl + X in X(2) matrices (X = H, D).

Science.gov (United States)

Korolkov, M V; Manz, J; Schild, A

2010-09-16

Six isotope effects (i)-(vi) are discovered for the reactions Cl + H(2)(ν) → HCl + H in solid para-H(2) ( 1 ) versus Cl + D(2)(ν) → DCl + D in ortho-D(2) ( 2 ), by means of quantum reaction dynamics simulations, within the frame of our simple model ( J. Phys. Chem. A 2009 , 113 , 7630 . ). Experimentally, the reactions may be initiated for ν = 0 and ν ≥ 1, by means of "UV only" photodissociation of the matrix-isolated precursor, Cl(2), or by "IR + UV" coirradiation ( Kettwich , S. C. , Raston , P. L. , and Anderson , D. T. J. Phys. Chem. A 2009 , 113 , 7621 . ), respectively. Specifically, (i) various shape and Feshbach reaction resonances correlate with vibrational thresholds of reactants and products, due to the near-thermoneutrality and low barrier of the system. The energetic density of resonances increases as the square root of mass, from M(X) = M(H) to M(D). (ii) The state selective reaction ( 1 ), ν = 1, is supported by a shape resonance, whereas this type of resonance is absent in ( 2 ), ν = 1. As a consequence, time-resolved measurements should monitor different three-step versus direct error-function type evolutions of the formation of the products. (iii) The effective barrier is lower for reaction 1 , ν = 0, enhancing the tunneling rate, as compared to that for reaction 2 , ν = 0. (iv) For reference, the reaction probabilities P versus total energy E(tot) in the gas exhibit sharp resonance peaks or zigzag behaviors of the reaction probability P versus total energy, near the levels of resonances ( Persky , A. and Baer , M. J. Chem. Phys . 1974 , 60 , 133 . ). These features tend to be washed out and broadened for reaction 1 , and even more so for reaction 2 . For comparison, they disappear for reactions in classical solids. (v) The slopes of P versus E(tot) below the potential barrier increase more steeply for reaction 1 , ν = 0, than for reaction 2 , ν = 0. This enhances the tunneling rate of the heavier isotopomer, reaction 2 , ν = 0

Synthesis of 2D Nitrogen-Doped Mesoporous Carbon Catalyst for Oxygen Reduction Reaction

Directory of Open Access Journals (Sweden)

Zhipeng Yu

2017-02-01

Full Text Available 2D nitrogen-doped mesoporous carbon (NMC is synthesized by using a mesoporous silica film as hard template, which is then investigated as a non-precious metal catalyst for the oxygen reduction reaction (ORR. The effect of the synthesis conditions on the silica template and carbon is extensively investigated. In this work, we employ dual templates—viz. graphene oxide and triblock copolymer F127—to control the textural features of a 2D silica film. The silica is then used as a template to direct the synthesis of a 2D nitrogen-doped mesoporous carbon. The resultant nitrogen-doped mesoporous carbon is characterized by transmission electron microscopy (TEM, nitrogen ad/desorption isotherms, X-ray photoelectron spectroscopy (XPS, cyclic voltammetry (CV, and rotating disk electrode measurements (RDE. The electrochemical test reveals that the obtained 2D-film carbon catalyst yields a highly electrochemically active surface area and superior electrocatalytic activity for the ORR compared to the 3D-particle. The superior activity can be firstly attributed to the difference in the specific surface area of the two catalysts. More importantly, the 2D-film morphology makes more active sites accessible to the reactive species, resulting in a much higher utilization efficiency and consequently better activity. Finally, it is noted that all the carbon catalysts exhibit a higher ORR activity than a commercial Pt catalyst, and are promising for use in fuel cells.

Forward absolute cross-section of the reaction /sup 2/H(d,n)/sup 3/He for Esub(d) = (3/6)MeV

Energy Technology Data Exchange (ETDEWEB)

Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R. (Padua Univ. (Italy). Ist. di Fisica); Galeazzi, G.

1981-12-01

The zero-degree differential cross-section of the reaction /sup 2/H(d,n)/sup 3/He was measured, by means of a recoil-proton neutron counter telescope, with an accuracy of 2%, in the incident-deuteron energy interval from 3 to 6 MeV.

Forward absolute cross-section of the reaction /sup 2/H(d,n)/sup 3/He for Esub(d)=(3/6)MeV

Energy Technology Data Exchange (ETDEWEB)

Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R. (Padua Univ. (Italy). Ist. di Fisica; Istituto Nazionale di Fisica Nucleare, Padua (Italy)); Galeazzi, G. (Istituto Nazionale di Fisica Nucleare, Padua (Italy). Lab. di Legnaro)

1981-12-01

The zero-degree differential cross-section of the reaction /sup 2/H(d,n)/sup 3/He was measured, by means of a recoil-proton neutron counter telescope, with an accuracy of 2%, in the incident deuteron energy interval form 3 to 6 MeV.

Structure of the excited states of {sup 11}Be reached through the reaction d({sup 10}Be,p){sup 11}Be; Structure des etats du {sup 11}Be excites par la reaction d({sup 10}Be,p){sup 11}Be

Energy Technology Data Exchange (ETDEWEB)

Delaunay, F

2003-10-01

The one-neutron transfer reaction d({sup 10}Be,p){sup 11}Be has been studied at 32 A.MeV at GANIL with a {sup 10}Be secondary beam. Protons were detected by the silicon strip array MUST. The ground state and excited states of {sup 11}Be at 0.32, 1.78 and 3.41 MeV were populated, demonstrating the feasibility of transfer reactions induced by radioactive beams leading to bound and unbound states. A DWBA (distorted wave born approximation) analysis indicates for the 3.41 MeV state spin and parity 3/2{sup +} or 5/2{sup +} and a spectroscopic factor of 0.18 or 0.11, respectively. A broad structure centered at 10 MeV is also observed and corresponds to transfer to the 1d sub-shells. If one assumes that only the 1d3/2 orbital contributes to this structure, the splitting of the 1d neutron states in {sup 11}Be is estimated to be 6.3 MeV. Using a 2-particle-RPA (random phase approximation) model, we have shown that neutron-neutron correlations play an important role in the inversion between the 2s1/2 and 1p1/2 neutron states in {sup 11}Be. (author)

Determination and theoretical analysis of the differential cross sections of the 2H(d,p) reaction at energies and detection angles suitable for NRA (Nuclear Reaction Analysis)

International Nuclear Information System (INIS)

Paneta, V.; Axiotis, M.; Lagoyannis, A.; Gastis, P.; Kokkoris, M.; Vlastou, R.; Kontos, A.; Mayer, M.; Misaelides, P.; Perdikakis, G.

2014-01-01

The accurate determination of deuteron depth profile presents a strong analytical challenge for all the principal IBA (Ion Beam Analysis) techniques. As far as NRA (Nuclear Reaction Analysis) is concerned, the 2 H(d,p) reaction, seems to be a promising candidate, especially in the case of complex matrices, or for the study of deep-implanted deuteron layers. In the present work differential cross-section values for the 2 H(d,p) reaction have been determined at 140, 160 and 170 degrees, for E d (lab) = 900-1600 keV, with an energy step of 50 keV, using a well-characterized, thin C:D target deposited on a polished Si wafer. The detection system consisted of 3 silicon surface barrier (SSB) detectors (thickness of 1000 μm) placed at a distance of about 11-13 cm from the target, at the appropriate angles. The experimental results were analyzed using the R-matrix calculations code AZURE. The results, in graphical and tabular form, will soon be available to the scientific community through IBANDL

Structure of the excited states of 11Be reached through the reaction d(10Be,p)11Be

International Nuclear Information System (INIS)

Delaunay, F.

2003-10-01

The one-neutron transfer reaction d( 10 Be,p) 11 Be has been studied at 32 A.MeV at GANIL with a 10 Be secondary beam. Protons were detected by the silicon strip array MUST. The ground state and excited states of 11 Be at 0.32, 1.78 and 3.41 MeV were populated, demonstrating the feasibility of transfer reactions induced by radioactive beams leading to bound and unbound states. A DWBA (distorted wave born approximation) analysis indicates for the 3.41 MeV state spin and parity 3/2 + or 5/2 + and a spectroscopic factor of 0.18 or 0.11, respectively. A broad structure centered at 10 MeV is also observed and corresponds to transfer to the 1d sub-shells. If one assumes that only the 1d3/2 orbital contributes to this structure, the splitting of the 1d neutron states in 11 Be is estimated to be 6.3 MeV. Using a 2-particle-RPA (random phase approximation) model, we have shown that neutron-neutron correlations play an important role in the inversion between the 2s1/2 and 1p1/2 neutron states in 11 Be. (author)

Development of an immunoassay for determination of 2,4-dichlorophenoxyacetic acid (2,4-D) based upon the recombinant Fab fragment of 2,4-D specific antibody

Science.gov (United States)

Nguyen, Van C.; Nguyen, Thi D. T.; Dau, Hung A.; Tham, Thu N.; Quyen, Dinh T.; Bachmman, Till; Schmid, Rolf D.

2001-09-01

To develop an immunoassay and further an immunosensor for 2,4-D based upon recombinant antibody, the Fab fragments of 2,4-D specific antibody were expressed in E. coli. Western blotting analysis of the periplasmic cell fractions shown that under the non-reducing condition only a single protein band at a molecular mass of 45-kDa, corresponding to the whole Fab fragment was detected. Antigen binding activity for 2,4-D was found only in the extract of cells bearing the 2,4-D plasmid. An immunoassay based on the competitive reaction of 2,4-D and enzyme tracer with 2,4-D Fab fragments immobilized on micro titer plates via rabbit anti-mouse IgC was developed. Using this assay, 2,4-D could be detected at concentration range of 0.5 (mu) g/1 to 10(mu) g/1. The center point of the 2,4-D test was found at a concentration of 5 (mu) g/l. The assay was applied for detection of 2,4-D in spiked orange samples, resulting in recovery rate of 90 percent. The immunoassay could be applied to monitor human exposure to 2,4-D from contamination in fruit samples.

A D-D/D-T fusion reaction based neutron generator system for liver tumor BNCT

International Nuclear Information System (INIS)

Koivunoro, H.; Lou, T.P.; Leung, K. N.; Reijonen, J.

2003-01-01

Boron-neutron capture therapy (BNCT) is an experimental radiation treatment modality used for highly malignant tumor treatments. Prior to irradiation with low energetic neutrons, a 10B compound is located selectively in the tumor cells. The effect of the treatment is based on the high LET radiation released in the 10 B(n,α) 7 Li reaction with thermal neutrons. BNCT has been used experimentally for brain tumor and melanoma treatments. Lately applications of other severe tumor type treatments have been introduced. Results have shown that liver tumors can also be treated by BNCT. At Lawrence Berkeley National Laboratory, various compact neutron generators based on D-D or D-T fusion reactions are being developed. The earlier theoretical studies of the D-D or D-T fusion reaction based neutron generators have shown that the optimal moderator and reflector configuration for brain tumor BNCT can be created. In this work, the applicability of 2.5 MeV neutrons for liver tumor BNCT application was studied. The optimal neutron energy for external liver treatments is not known. Neutron beams of different energies (1eV < E < 100 keV) were simulated and the dose distribution in the liver was calculated with the MCNP simulation code. In order to obtain the optimal neutron energy spectrum with the D-D neutrons, various moderator designs were performed using MCNP simulations. In this article the neutron spectrum and the optimized beam shaping assembly for liver tumor treatments is presented

Molar extinction coefficients and other properties of an improved reaction center preparation from Rhodopseudomonas viridis

Energy Technology Data Exchange (ETDEWEB)

Clayton, R.K.; Clayton, B.J.

1978-01-01

Reaction centers have been purified from chromatophores of Rhodopseudomonas viridis by treatment with lauryl dimethyl amine oxide followed by hydroxyapatite chromatography and precipitation with ammonium sulfate. The absorption spectrum at low temperature shows bands at 531 and 543 nm, assigned to two molecules of bacteriopheophytin b. The 600 nm band of bacteriochlorophyll b is resolved at low temperature into components at 601 and 606.5 nm. At room temperature the light-induced difference spectrum shows a negative band centered at 615 nm, where the absorption spectrum shows only a week shoulder adjacent to the 600 nm band. The fluorescence spectrum shows a band at 1000 nm and no fluorescence corresponding to the 830 nm absorption band. Two molecules of cytochrome 558 and three of cytochrome 552 accompany each reaction center. The differential extinction coefficient (reduced minus oxidized) of cytochrome 558 nm was estimated as 20 +- 2 mM/sup -1/.cm/sup -1/ through a coupled reaction with equine cytochrome c. The extinction coefficient of reaction centers at 960 nm was determined to be 123 +- 25 mM/sup -1/.cm/sup -1/ by measuring the light-induced bleaching of P-960 and the coupled oxidation of cytochrome 558. The corresponding extinction coefficient at 830 nm is 300 +- 65 mM/sup -1/.cm/sup -1/. The absorbance ratio ..cap alpha../sub 280nm/..cap alpha../sub 830nm/ in our preparations was 2.1, and there was 190 kg protein per mol of reaction centers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed three major components of apparent molecular weights 31,000, 37,000, and 41,000.

Direct observation of forward-scattering oscillations in the H+HD→H2+D reaction

Science.gov (United States)

Yuan, Daofu; Yu, Shengrui; Chen, Wentao; Sang, Jiwei; Luo, Chang; Wang, Tao; Xu, Xin; Casavecchia, Piergiorgio; Wang, Xingan; Sun, Zhigang; Zhang, Dong H.; Yang, Xueming

2018-06-01

Accurate measurements of product state-resolved angular distributions are central to fundamental studies of chemical reaction dynamics. Yet, fine quantum-mechanical structures in product angular distributions of a reactive scattering process, such as the fast oscillations in the forward-scattering direction, have never been observed experimentally and the nature of these oscillations has not been fully explored. Here we report the crossed-molecular-beam experimental observation of these fast forward-scattering oscillations in the product angular distribution of the benchmark chemical reaction, H + HD → H2 + D. Clear oscillatory structures are observed for the H2(v' = 0, j' = 1, 3) product states at a collision energy of 1.35 eV, in excellent agreement with the quantum-mechanical dynamics calculations. Our analysis reveals that the oscillatory forward-scattering components are mainly contributed by the total angular momentum J around 28. The partial waves and impact parameters responsible for the forward scatterings are also determined from these observed oscillations, providing crucial dynamics information on the transient reaction process.

Direct production of D-arabinose from D-xylose by a coupling reaction using D-xylose isomerase, D-tagatose 3-epimerase and D-arabinose isomerase.

Science.gov (United States)

Sultana, Ishrat; Mizanur, Rahman Md; Takeshita, Kei; Takada, Goro; Izumori, Ken

2003-01-01

Klebsiella pneumoniae 40bXX, a mutant strain that constitutively produces D-arabinose isomerase (D-AI), was isolated through a series of repeated subcultures from the parent strain on a mineral salt medium supplemented with L-Xylose as the sole carbon source. D-AI could be efficiently immobilized on chitopearl beads. The optimum temperature for the activity of the immobilized enzyme was 40 degrees C and the enzyme was stable up to 50 degrees C. The D-Al was active at pH 10.0 and was stable in the range of pH 6.0-11.0. The enzyme required manganese ions for maximum activity. Three immobilized enzymes, D-xylose isomerase (D-XI), D-tagatose 3-epimerase (D-TE and D-AI were used for the preparation of D-arabinose from D-xylose in a coupling reaction. After completion of the reaction, degradation of D-xylulose was carried out by Saccharomyces cerevisiae. The reaction mixture containing D-Xylose, D-ribulose and the product was then separated by ion exchange column chromatography. After crystallization, the product was checked by HPLC, IR spectroscopy, NMR spectroscopy and optical rotation measurements. Finally, 2.0 g of D-arabinose could be obtained from 5 g of the substrate.

197Au(d,3He)196Pt reaction and the supersymmetry scheme

International Nuclear Information System (INIS)

Vergnes, M.; Berrier-Ronsin, G.; Rotbard, G.; Vernotte, J.; Langevin- Joliot, H.; Gerlic, E.; Wiele, J. van de; Guillot, J.

1981-01-01

The 197 Au(d, 3 He) 196 Pt reaction has been studied at Esub(d) = 108 MeV. An important breakdown of the selection rules of the supersymmetry scheme is observed for the 2 2 + level. The generally strong excitation of the 2 2 + level by transfer reactions in the Pt region leads to question the validity of the supersymmetry scheme at least for this level

A zero-degree spectrometer in Celsius and the d(d,2π)4He reaction

International Nuclear Information System (INIS)

Thoerngren Engblom, P.

1996-02-01

For the realization of near threshold studies a small-size spectrometer has been developed by the Nuclear Physics Division at Stockholm University in conjunction with Institut fuer Kernphysik in Juelich. A particle telescope is mounted inside the CELSIUS vacuum chamber in the bend following the cluster-jet target. It is possible to vary the measuring position within the dipole field to cover different magnetic rigidities which makes it a versatile tool for studies of threshold reactions. The first aim has been to study two-pion production and the present paper is a report on the experimental set-up and data analysis of measurements of the reaction d+d→ 4 He+X. Detection of the 4 He-particle yields information about the missing mass, i.e. the remainder of the reaction products. Preliminary results are presented. 22 refs

A paradox: The thermal rate coefficient for the H+DCl → HCl+D exchange reaction

International Nuclear Information System (INIS)

Thompson, D.L.; Suzukawa, H.H. Jr.; Raff, L.M.

1975-01-01

Previously reported photolysis experiments indicate that the frequency factors associated with the hydrogen-exchange reactions H+DCl → HCl+D and D+HCl → DCl+H are on the order of 10 10 cm 3 /molcenter-dotsec. A series of unadjusted, quasiclassical trajectory calculations were been carried out to compute the thermal rate coefficients and activation parameters for a series of 13 thermal processes of the type A+BC → AB+C, where A=H, D, or Cl and BC=H 2 , D 2 , HCl, DCl, or Cl 2 . In addition, hot-atom yield ratios have been computed from the IRP equation for the reactions D*+DCl → D 2 +Cl, D*+Cl 2 → DCl + Cl as a function of the initial D* laboratory energy. The computations yield (1) hot-atom DCl/D 2 yield ratios within a factor of 2 of the experimental values; (2) thermal activation energies in satisfactory agreement with experiment for all processes investigated; and (3) frequency factors in reasonable accord with experiment for all the reactions except the hydrogen exchange reactions

Reaction of uranium and plutonium carbides with nitrogen; Reaction avec l'azote des carbures d'uranium et de plutonium

Energy Technology Data Exchange (ETDEWEB)

Lorenzelli, R; Martin, A; Schickel, R [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1966-03-01

Uranium and plutonium carbides react with nitrogen during the grinding process preceding the final sintering. The reaction occurs even in argon atmospheres containing a few percent of residual nitrogen. The resulting contamination is responsible for the appearance of an equivalent quantity of higher carbide in the sintered products; nitrogen remains quantitatively in the monocarbide phase. UC can be transformed completely into nitride under a nitrogen pressure, at a temperature as low as 400 C. The reaction is more sluggish with PuC. The following reactions take places: UC + 0,8 N{sub 2} {yields}> UN{sub 1.60} + C and PuC + 0,5 N{sub 2} {yields} PuN + C. (authors) [French] Les carbures d'uranium et de plutonium reagissent avec l'azote au cours du broyage qui precede le frittage final. Cette reaction est sensible meme sous des atmospheres d'argon ne contenant que quelques pour cent d'azote. Cette contamination se traduit sur les produits frittes par l'apparition d'une quantite equivalente de carbure superieur, l'azote restant fixe quantitativement dans la phase monocarbure. On peut transformer entierement UC en nitrure par action de l'azote sous pression des 400 C. La reaction est plus difficile avec PuC. Les reactions sont les suivantes: UC + 0,8 N{sub 2} {yields} UN{sub 1.60} + C et PuC + 0,5 N{sub 2} {yields} PuN + C.

Temperature dependence of third order ion molecule reactions. The reaction H+3 + 2H2 = H+5 + H2

International Nuclear Information System (INIS)

Hiraoka, K.; Kebarle, P.

1975-01-01

The rate constants k 1 for Reaction (1): H + 3 +2H 2 = H + 5 +H 2 were measured in the temperature range 100--300 degreeK. The temperature dependence of k 1 has the form k 1 proportionalT - /subn/, where n=2.3. Pierce and Porter have reported a much stronger negative temperature dependence with n=4.6. The difference arises from a determination of k 1 at 300 degreeK obtained by Arifov and used by Porter. The present k 1 (300 degreeK) =9times10 -30 (cm 6 molecules -2 center-dotsec -1 ). This is more than an order of magnitude larger than the Arifov value. The temperature dependence of third body dependent association reactions like (1) is examined on the basis of the energy transfer theory and the recently proposed trimolecular complex transition state theory by Meot-Ner, Solomon, Field, and Gershinowitz. The temperature dependence of the rate constant for the reverse reaction (-1) is obtained from k 1 and the previously determined temperature dependence of the equilibria (1). k/sub -//sub 1/ gives a good straight line Arrhenius plot leading to k/sub -//sub 1/ =8.7times10 -6 exp(-8.4/RT) cm 3 molecules -1 center-dotsec -1 . The activation energy is in kcal/mole. The preexponential factor is much larger than the rate constant for Langevin collisions. This is typical for pyrolysis of ions involving second order activation

Quantum measurement corrections to CIDNP in photosynthetic reaction centers

International Nuclear Information System (INIS)

Kominis, Iannis K

2013-01-01

Chemically induced dynamic nuclear polarization is a signature of spin order appearing in many photosynthetic reaction centers. Such polarization, significantly enhanced above thermal equilibrium, is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long-lived charge-separated states in photosynthetic reaction centers. We will show here that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and completely unexpected pathway toward obtaining chemically induced dynamic nuclear polarization signals. The fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations of the order of 10 4 times (or more) higher than the thermal equilibrium value at the Earth's magnetic field relevant to natural photosynthesis. This opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis. (paper)

Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

Science.gov (United States)

Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

2017-06-01

Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

Azimuthal anisotropy of D -meson production in Pb-Pb collisions at sNN =2.76 TeV

NARCIS (Netherlands)

Abelev, B.; Adam, J.; Adamová, D.; Aggarwal, M. M.; Agnello, M.; Agostinelli, A.; Agrawal, N.; Ahammed, Z.; Ahmad, N.; Ahmed, I.; Ahn, S. U.; Ahn, S. A.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Baumann, C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Belmont, R.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Berger, M. E.; Bertens, R. A.|info:eu-repo/dai/nl/371577810; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.|info:eu-repo/dai/nl/371578248; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Bjelogrlic, S.|info:eu-repo/dai/nl/355079615; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Böhmer, F. V.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bossú, F.; Botje, M.|info:eu-repo/dai/nl/070139032; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.|info:eu-repo/dai/nl/411885812; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Casula, E. A R; Catanescu, V.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Chojnacki, M.|info:eu-repo/dai/nl/411888056; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortese, P.; Cortés Maldonado, I.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dainese, A.; Dang, R.; Danu, A.; Das, D.; Das, I.; Das, K.; Das, S.; Dash, A.; Dash, S.; De, S.; Delagrange, H.; Deloff, A.; Dénes, E.; D'Erasmo, G.; De Caro, A.; De Cataldo, G.; De Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; De Rooij, R.|info:eu-repo/dai/nl/315888644; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Di Bari, D.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Djuvsland, O.; Dobrin, A.|info:eu-repo/dai/nl/372618715; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dørheim, S.; Dubey, A. K.; Dubla, A.|info:eu-repo/dai/nl/355502488; Ducroux, L.; Dupieux, P.; Dutta Majumdar, A. K.; Hilden, T. E.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdal, H. A.; Eschweiler, D.; Espagnon, B.; Esposito, M.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Fasel, M.; Fehlker, D.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A S; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floratos, E.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Garishvili, I.; Gerhard, J.; Germain, M.; Gheata, A.; Gheata, M.; Ghidini, B.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Graczykowski, L. K.; Grajcarek, R.; Grelli, A.|info:eu-repo/dai/nl/326052577; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J. Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Guilbaud, M.; Gulbrandsen, K.; Gulkanyan, H.; Gumbo, M.; Gunji, T.; Gupta, A.; Gupta, R.; Khan, K. H.; Haake, R.; Haaland, O.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hippolyte, B.; Hladky, J.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Innocenti, G. M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Jachołkowski, A.; Jacobs, P. M.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H S Y; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kadyshevskiy, V.; Kalcher, S.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L D|info:eu-repo/dai/nl/370530780; Khan, M. M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Konevskikh, A.; Kovalenko, V.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kramer, F.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.|info:eu-repo/dai/nl/362845670; Kučera, V.; Kucheriaev, Y.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.|info:eu-repo/dai/nl/074064975; Kulakov, I.; Kumar, J.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; Ladron De Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; La Pointe, S. L.|info:eu-repo/dai/nl/355080192; La Rocca, P.; Lea, R.; Leardini, L.; Lee, G. R.; Legrand, I.; Lehnert, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; Leoncino, M.; León Monzón, I.; Lévai, P.; Li, S.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Lohner, D.; Loizides, C.; Lopez, X.; López Torres, E.; Lu, X. G.; Luettig, P.; Lunardon, M.; Luparello, G.|info:eu-repo/dai/nl/355080400; Ma, R.; Maevskaya, A.; Mager, M.; Mahapatra, D. P.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Marín, A.; Markert, C.; Marquard, M.; Martashvili, I.; Martin, N. A.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martin Blanco, J.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Meddi, F.; Menchaca-Rocha, A.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Mischke, A.|info:eu-repo/dai/nl/325781435; Mishra, A. N.; Mis̈kowiec, D.; Mitra, J.; Mitu, C. M.; Mlynarz, J.; Mohammadi, N.|info:eu-repo/dai/nl/369405870; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira De Godoy, D. A.; Moretto, S.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Müller, H.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nicassio, M.; Niculescu, M.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Nilsen, B. S.; Noferini, F.; Nomokonov, P.; Nooren, G.|info:eu-repo/dai/nl/07051349X; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Okatan, A.; Olah, L.; Oleniacz, J.; Oliveira Da Silva, A. C.|info:eu-repo/dai/nl/323375618; Onderwaater, J.; Oppedisano, C.; Ortiz Velasquez, A.; Ortona, G.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Sahoo, P.; Pachmayer, Y.; Pachr, M.; Pagano, P.; Paić, G.; Painke, F.; Pajares, C.; Pal, S. K.; Palmeri, A.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Patalakha, D. I.; Paticchio, V.; Paul, B.; Pawlak, T.; Peitzmann, T.|info:eu-repo/dai/nl/304833959; Pereira Da Costa, H.; Pereira De Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Pesci, A.; Peskov, V.; Pestov, Y.; Petráček, V.; Petran, M.; Petris, M.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L M; Poghosyan, M. G.; Pohjoisaho, E. H O; Polichtchouk, B.; Poljak, N.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Potukuchi, B.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Rauf, A. W.; Razazi, V.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reicher, M.|info:eu-repo/dai/nl/32823219X; Reidt, F.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J. P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohni, S.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, R.; Sahu, P. K.; Saini, J.; Sakai, S.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Sánchez Rodríguez, F. J.; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Segato, G.; Seger, J. E.; Sekiguchi, Y.; Selyuzhenkov, I.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabetai, A.; Shabratova, G.; Shahoyan, R.; Shangaraev, A.; Sharma, N.; Sharma, S.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Sicking, E.; Siddhanta, S.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Skjerdal, K.; Slupecki, M.; Smirnov, N.; Snellings, R. J M|info:eu-repo/dai/nl/165585781; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Stolpovskiy, M.; Strmen, P.; Suaide, A. A P; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Susa, T.; Symons, T. J M; Szabo, A.; Szanto De Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tarazona Martinez, A.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terrevoli, C.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; Vande Vyvre, P.; Van Der Maarel, J.|info:eu-repo/dai/nl/412860996; Van Hoorne, J. W.; Van Leeuwen, M.|info:eu-repo/dai/nl/304836737; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vechernin, V.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; Von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wagner, V.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C S; Windelband, B.; Winn, M.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yang, S.; Yano, S.; Yasnopolskiy, S.; Yi, J.; Yin, Z.; Yoo, I. K.; Yushmanov, I.; Zaccolo, V.; Zach, C.; Zaman, A.; Zampolli, C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, F.|info:eu-repo/dai/nl/304845035; Zhou, Y.; Zhou, Zhuo; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zoccarato, Y.; Zyzak, M.

2014-01-01

The production of the prompt charmed mesons D0, D+, and D∗+ relative to the reaction plane was measured in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon collision of sNN=2.76TeV with the ALICE detector at the CERN Large Hadron Collider. D mesons were reconstructed via their

Hydrogen-deuterium exchange reaction of 2-methylpyridine catalyzed by several fatty acids

International Nuclear Information System (INIS)

Hirata, Hirohumi; Fukuzumi, Kazuo.

1976-01-01

Hydrogen-deuterium exchange reaction of 2-methylpyridine has been studied by using several fatty acids as catalysts. The reaction was carried out in a sealed pyrex tube at 120 0 C, and the contents of the products were determined by mass spectrometry. Reaction of 2-methylpyridine with monodeuteroacetic acid (1 : 1, mol/mol) arrived at a equilibrium (d 0 reversible d 1 reversible d 2 reversible d 3 ) in 2 hr (d 0 41%, d 1 42%, d 2 15%, d 3 2%). No exchange was observed for the reaction of pyridine with monodeuteroacetic acid. The conversion-time curves of typical series reactions (d 0 → d 1 → d 2 → d 3 ) were obtained for the fatty acid catalyzed exchange in deuterium oxide. The effect of the fatty acid RCO 2 H (substrate : fatty acid : D 2 O=1 : 0.86 : 27.6, mol/mol/mol) on the conversion was in the order of R; C 1 --C 3 4 --C 10 , where the reaction mixtures were homogeneous in the case of C 1 --C 3 and were heterogeneous in the case of C 4 --C 10 . The effects of the initial concentration of the substrates and the catalysts (RCO 2 H) on the total conversion were studied by using some fatty acids (R; C 2 , C 4 and C 9 ) in deuterium oxide (for 2 hr). The total conversion of the substrate increases with increasing the concentration of the acids. The total conversion decreases in the case of R=C 9 , but, increases in the case of R=C 2 with increasing the concentration of the substrate. In the case of reactions with low concentrations of the substrate, the reactivity was in the order of C 9 >C 4 >C 2 , while with high concentrations, the reactivity was in the order of C 4 >C 2 >C 9 and C 9 >C 4 >C 2 with high and low concentrations of the acids, respectively. A possible reaction mechanism was proposed and discussed. (auth.)

Polarization transfer in (d-vector,n-vector) reactions

International Nuclear Information System (INIS)

Walter, R.L.; Tornow, W.

1986-01-01

The status of the measurements and the role of polarization transfer coefficients for (d/sup →/,n/sup →/) reactions is reviewed. Emphasis is given to reactions, involving light-nuclei systems. The importance of (d/sup →/,n/sup →/) reactions as sources of polarized neutrons is pointed out

α-particle D-state effects in (d,α) reactions

International Nuclear Information System (INIS)

Santos, F.D.; Tonsfelt, S.A.; Clegg, T.B.; Ludwig, E.J.; Tagishi, Y.; Wilkerson, J.F.

1982-01-01

It is shown that the tensor analyzing powers for (d,α) reactions are sensitive to the D-state component in the α-particle wave function. The D to S-state asymptotic ratio extracted from T 20 and T 22 data in J = L +- 1 transitions is discussed using an α-particle D state generated with the Jackson and Riska model

Excitation function and yield for the 103Rh(d,2n)103Pd nuclear reaction: Optimization of the production of palladium-103

International Nuclear Information System (INIS)

Manenti, Simone; Alí Santoro, María del Carmen; Cotogno, Giulio; Duchemin, Charlotte; Haddad, Ferid; Holzwarth, Uwe; Groppi, Flavia

2017-01-01

Deuteron-induced nuclear reactions for the generation of 103 Pd were investigated using the stacked-foil activation technique on rhodium targets at deuteron energies up to E d = 33 MeV. The excitation functions of the reactions 103 Rh(d,xn) 101,103 Pd, 103 Rh(d,x) 100g,cum,101m,g,102m,g Rh and 103 Rh(d,2p) 103 Ru have been measured, and the Thick-Target Yield for 103 Pd has been calculated.

Part 1: Kinetic energy dependencies of selected ion-molecule reactions; Part 2: Photochemistry of (FSO3)2, FSO3, and FNO

International Nuclear Information System (INIS)

Burley, J.D.

1991-07-01

In Part 1, guided ion beam mass spectroscopy is used to study the ion-molecule reactions O + ( 4 S) + H 2 (D 2 , HD), (O +4 S) + N 2 , C + ( 2 P) + O 2 and C + (P) + N 2 . Integral reaction cross sections are measured as a function of kinetic energy in the center-of-mass frame. Reaction mechanisms and dynamics are examined, and the results are compared to the predictions of phase space theory. In some cases, thermochemistry for neutral and ionic species is derived. In Part 2, photoabsorption cross sections are measured for peroxydisulfuryl difluoride, (FSO 3 ) 2 , and the fluorosulfate radical, FSO 3 . Photoabsorption cross sections of nitrosyl fluoride, FNO, are also measured, and the FNO absorption spectrum is analyzed and assigned. Spectral results for FNO are compared to the predictions and ab initio calculations and to those obtained for the isoelectronic compound HONO. 259 refs., 34 figs., 9 tabs

Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

Energy Technology Data Exchange (ETDEWEB)

Mermaz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

Energy Technology Data Exchange (ETDEWEB)

Mermaz, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

Modeling and analysis of liquid deuterium-water reactions

International Nuclear Information System (INIS)

Taleyarkhan, R.P.

1995-01-01

This Presentation highlights the following: Overview of LD 2 -water reactions their connections to research reactors with cold sources; some key features and ingredients of vapor explosions in general; Examination of results of 1970 experiment at Grenoble Nuclear Research Center; Thermodynamic evaluations of energetics of explosive LD 2 -D 2 O reactions. This presentation concentrates only on the technical aspects of LD 2 /LH 2 - water reactions; it is not intended to draw/imply safety-related conclusions for research reactors

The Type 1 Homodimeric Reaction Center in Heliobacterium modesticaldum

Energy Technology Data Exchange (ETDEWEB)

Golbeck, John [Pennsylvania State Univ., University Park, PA (United States)

2018-01-15

In this funding period, we (i) found that strong illumination of Heliobacterium modesticaldum cells results in saturation of the electron acceptor pool, leading to reduction of the acceptor side and the creation of a back-reacting state that gives rise to delayed fluorescence; (ii) noted that when the FX cluster is reduced in purified reaction centers, no electron transfer occurs beyond A0, even though a quinone is present; (iii) observed by photochemically induced dynamic nuclear polarization (photo-CIDNP) studies of whole cells of Heliobacterium mobilis that primary charge separation is retained even after conversion of the majority of BChl g to Chl aF. ; and (iv) purified a homogeneous preparation of reaction center cores, which led to promising crystallization trials to obtain a three-dimensional structure.

Realisation and crossed molecular beams study of H2/O chemical reactions at several excited states

International Nuclear Information System (INIS)

Marx, Jacqueline

1986-01-01

This work is devoted to the study of the reactive collision O + H 2 OH + H in a crossed beam experiment. This process including several channels taken a part in the chemistry of the upper atmosphere as well as in the combustion of hydrogen. According to the electronic or vibrational state of the reactants, the OH radical is produced in its ground electronic state OH (X 2 π) or in its first excited state OH (A 2 Σ + ). When the reactants are in their ground state, the reaction is endothermic in the conditions of the experiment (center of mass kinetic energy ≅ 0.12 eV). The following reactions have been obtained: O( 1 D) +H 2 (v=O) → OH (X 2 π) +H( 2 S) and O( 1 D) +H 2 (v≥5) → OH (A 2 Σ + ) +H( 2 S). The atomic oxygen is produced in its excited state O( 1 D) in a radio-frequency discharge which dissociates the molecular oxygen seeded in a carrier gas (He or Ar) and the hydrogen molecules are excited vibrationally by electron bombardment. The first reaction is studied by time-of-flight measurements. In this way, it has been possible to observe the different vibrational levels on which the OH radical is produced. The analysis of this vibrational distribution shows the competition between the abstraction and insertion-dissociation mechanisms. In the second reaction, the analysis of the spontaneous fluorescence of OH (A 2 Σ + ) reveals a very hot and non-Boltzmann rotational excitation. (author) [fr

1g(9/2), 1f(5/2), and 1f(7/2) neutron inner hole responses in Sn-115 and Sn-119 via the ((d)over-right-arrow,t) reaction at E-d=200 MeV

NARCIS (Netherlands)

Langevin-Joliot, H; Van de Wiele, J; Guillot, J; Gerlic, E; Rosier, LH; Willis, A; Djalali, C; Morlet, M; Tomasi-Gustafsson, E; Blasi, N; Micheletti, S; van der Werf, SY

Neutron inner hole responses in Sn-115 and Sn-119 nuclei have been studied via the ((d) over right arrow ,t) reaction at E-d=200 MeV using a polarized beam with both vector and tensor components. One-step pickup observables corresponding to the overlapping 1g(9/2), 1f(5/2), and 1f(7/2) responses

Study of the (p,d3He) reaction as a quasi-free reaction process

International Nuclear Information System (INIS)

Cowley, A.A.; Roos, P.G.; Chant, N.S.; Woody, R. III; Holmgren, H.D.; Goldberg, D.A.

1976-11-01

The (p,d 3 He) reaction on 6 Li, 7 Li, 9 Be, and 12 C has been investigated in conjunction with studies of the (p,pα) reaction on the same targets. Coincident data for all four targets were obtained at a bombarding energy of 100 MeV for numerous angle pairs in order to test the reaction mechanism. Comparisons of the (p,d 3 He) data to both (p,pα) data and distorted wave impulse approximation calculations (DWIA) indicate a dominance of the direct quasi-free reaction process (p + alpha yields d + 3 He). The absolute alpha-particle spectroscopic factors extracted using DWIA analysis are in agreement with the values obtained in the (p,pα) reaction

Contribution to the study of (d,p) and (d,{alpha}> reactions on {sup 16}O and {sup 11}B from 200 keV to 1 MeV; Contribution a l'etude des reactions (d,p) et (d,{alpha}) sur {sup 16}O et {sup 11}B de 200 keV a 1 MeV

Energy Technology Data Exchange (ETDEWEB)

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

1965-05-01

The reactions {sup 16}O(d,{alpha}{sub 0}), (d,p{sub 0}), (d,p{sub 1}) and {sup 11}B(d,{alpha}{sub 0}), (d,{alpha}{sub 2}), (d,p{sub 0}) have been studied from 200 keV to 1 MeV. The interpretation of (d,{alpha}) reactions by the compound nucleus theory has shown the presence of {sup 18}F levels (7,94 MeV, 1+; 8,09 MeV, 1+ ) and of {sup 13}C level (19 MeV, 3/2{+-} or 5/2-). The interpretation of {sup 16}O(d,p{sub 1}) and {sup 11}B(d,p{sub 0}) reactions at energies lower than 400 keV has been given by a theory of Coulomb stripping. (author) [French] L'etude experimentale des reactions {sup 16}O(d,{alpha}{sub 0}); (d,p{sub 0}), (d,p{sub 1}) et {sup 11}B(d,{alpha}{sub 0}), (d,{alpha}{sub 2}), (d,p{sub 0}) a ete faite de 200 keV a 1 Mev. L'interpretation des reactions (d,a) par la theorie du noyau compose a permis la mise en evidence de niveaux du {sup 18}F (7,94 MeV, 1+; 8,09MeV, 1+ ) et du {sup 13}C(19 MeV, 3/2{+-} ou 5/2-). L'interpretation des reactions {sup 16}O(d,p{sub 1}) et {sup 11}B(d,p{sub 0}), a basse energie (< 400 keV), par une theorie de stripping de Coulomb, a ete donnee.

Forward absolute cross section of the reaction /sup 2/H(d,n)/sup 3/He from E/sub d/ = 3 to 6 MeV

Energy Technology Data Exchange (ETDEWEB)

Galeazzi, G.; Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.

1981-01-15

The zero degree differential cross section of the reaction /sup 2/H(d,n)/sup 3/He was measured, by means of a proton recoil neutron counter telescope, with an accuracy of 2%, in the incident deuteron energy interval from 3 to 6 MeV. Results are presented.

Nucleon transfer reactions in D.W.B.A; Les reactions de transfert d'un nucleon dans la D.W.B.A

Energy Technology Data Exchange (ETDEWEB)

Giraud, B; Picard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-08-01

The DWBA for one nucleon transfer reaction is described as simply and completely as possible to show the possibilities and limits of this method. The extraction of spectroscopic factors is described in the appendix. (authors) [French] Le formalisme de la DWBA est decrit d'une maniere aussi simple et complete que possible pour mettre en evidence les possibilites et les limites de cette methode d'analyse des reactions de transfert. L'extraction des facteurs spectroscopiques est exposee en appendice. (auteurs)

Crossed molecular beam study of H and D atom reactions with NO2

International Nuclear Information System (INIS)

Haberland, H.; Lucadou, W. von; Rohwer, P.

1976-01-01

Angular distributions and time of flight spectra of OH and OD from the reactions H + NO 2 and D + NO 2 have been measured at a relative kinetic energy of 440 meV (approximately 10 kcal/mol). Both angular distributions peak in the forward (atom beam) direction, the fall off to larger angles being more rapid for OD than for OH. Within statistical error the centre of mass velocity spectra do not show an isotope effect. Only 24 +- 5% of the total energy available is channeled into product translation independent of the isotope. This value is in very good agreement with our earlier results and with data from Polanyi and Sloans chemiluminescence experiments. (orig.) [de

Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2.

Science.gov (United States)

Lyu, Lai; Yan, Dengbiao; Yu, Guangfei; Cao, Wenrui; Hu, Chun

2018-04-03

Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO 2 substrate (CN-Cu(II)-CuAlO 2 ) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO 2 . According to the characterization, Cu(II) generation on the surface of CuAlO 2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C-O-Cu bridges between CN and Cu(II)-CuAlO 2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation-π interactions through the C-O-Cu bridges in CN-Cu(II)-CuAlO 2 . During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H 2 O 2 to • OH, and the electron-poor center around C captures electrons from H 2 O 2 or pollutants and diverts them to the electron-rich area via the C-O-Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.

η-nucleus interaction from the d + d reaction around the η production threshold

Energy Technology Data Exchange (ETDEWEB)

Ikeno, N. [Tottori University, Department of Life and Environmental Agricultural Sciences, Tottori (Japan); Nagahiro, H. [Nara Women' s University, Department of Physics, Nara (Japan); Osaka University, Research Center for Nuclear Physics (RCNP), Ibaraki (Japan); Jido, D. [Tokyo Metropolitan University, Department of Physics, Hachioji (Japan); Hirenzaki, S. [Nara Women' s University, Department of Physics, Nara (Japan)

2017-10-15

The η mesic nucleus is considered to be one of the interesting exotic many-body systems and has been studied since the 1980s theoretically and experimentally. Recently, the formation of the η mesic nucleus in the fusion reactions of the light nuclei such as d + d → (η + α) → X has been proposed and the experiments have been performed by WASA-at-COSY. We develop a theoretical model to evaluate the formation rate of the η mesic nucleus in the fusion reactions and show the calculated results. We find that the η bound states could be observed in the reactions in cases with the strong attractive and small absorptive η-nucleus interactions. We compare our results with existing data of the d + d → η + α and the d + d → {sup 3}He + N + π reactions. We find that the analyses by our theoretical model with the existing data can provide new information on the η-nucleus interaction. (orig.)

Nitrogen Detection in Bulk Samples Using a D-D Reaction-Based Portable Neutron Generator

Directory of Open Access Journals (Sweden)

A. A. Naqvi

2013-01-01

Full Text Available Nitrogen concentration was measured via 2.52 MeV nitrogen gamma ray from melamine, caffeine, urea, and disperse orange bulk samples using a newly designed D-D portable neutron generator-based prompt gamma ray setup. Inspite of low flux of thermal neutrons produced by D-D reaction-based portable neutron generator and interference of 2.52 MeV gamma rays from nitrogen in bulk samples with 2.50 MeV gamma ray from bismuth in BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays indicates satisfactory performance of the setup for detection of nitrogen in bulk samples.

Pion-transfer (n,d) and (d, 3He) reactions leading to deeply bound pionic atoms

International Nuclear Information System (INIS)

Toki, H.; Hirenzaki, S.; Yamazaki, T.

1990-11-01

Theoretical studies are given on the (n,d) and (d, 3 He) reactions leading to deeply bound pionic atoms in heavy nuclei of configuration [(nl) π ·j n -1 ]J. The cross sections for various pionic and neutron-hole configurations in the case of a 208 Pb target are calculated at incident energies 300-1000 MeV/u by using the effective number approach and the eikonal approximation for distortion. The effective number with a pion in the 1s or 2p state and a neutron hole in the i 13/2 orbit peaks around the same incident energy (T n =600 MeV) as the elementary cross section n+n→d+π - , where the momentum transfer matches the angular-momentum transfer of L=5∼7. The DWIA cross section for (n,d) producing a pion in the 1s or 2p orbit at T n =600 MeV is found to be around 42 or 75 μb/sr, respectively. At T n =350 MeV, where the momentum transfer is small, quasi-substitutional states of configurations [(2p) π (3p 1/2 ) n -1 ]L=0 and [(2p) π (3p 3/2 ) n -1 ]L=0 are preferentially populated with cross sections of 190 and 380 μb/sr, respectively. The (d, 3 He) cross sections are estimated to be an order of magnitude smaller than the (n,d) cross sections. Thus, the (n,d) and (d, 3 He) reactions are found to be suited for the production of deeply bound pionic atoms. (author)

Experimental Determination of the Possible Deuterium - Deuterium Fusion Reaction Originated in a Single Cavitation Bubble Luminescence System Using CDCL3 and D2 O

International Nuclear Information System (INIS)

Barbaglia, Mario; Florido, Pablo; Mayer, Roberto; Bonetto, Fabian

2003-01-01

We focus this work on the measurement of the possible Deuterium - Deuterium reaction in a SCBL (Single Cavitation Bubble Luminescence) system.We measure the possible reaction at the bubble generation time and at the bubble collapse time. We use a Nd:YAG laser and CDCl 3 and D 2 O as a medium to generate the bubble. Since CDCl 3 accommodation coefficient is best than that of D 2 O, it is expected a greater collapse force than using D 2 O.To benefit the bubble collapse violence, we diminish the temperature of the liquids.To avoid false neutron detection, we developed a measuring system with high background reject using the characteristic experiment times.No neutrons attributable to Deuterium - Deuterium fusion reaction were measured

1D to 3D diffusion-reaction kinetics of defects in crystals

DEFF Research Database (Denmark)

Trinkaus, H.; Heinisch, H.L.; Barashev, A.V.

2002-01-01

Microstructural features evolving in crystalline solids from diffusion-reaction kinetics of mobile components depend crucially on the dimension of the underlying diffusion process which is commonly assumed to be three-dimensional (3D). In metals, irradiation-induced displacement cascades produce...... clusters of self-interstitials performing 1D diffusion. Changes between equivalent 1D diffusion paths and transversal diffusion result in diffusion-reaction kinetics between one and three dimensions. An analytical approach suggests a single-variable function (master curve) interpolating between the 1D...

Fluor Hanford ALARA Center is a D and D Resource

International Nuclear Information System (INIS)

Waggoner, L.O.

2008-01-01

The mission at the Hanford Nuclear Reservation changed when the last reactor plant was shut down in 1989 and work was started to place all the facilities in a safe condition and begin decontamination, deactivation, decommissioning, and demolition (D and D). These facilities consisted of old shutdown reactor plants, spent fuel pools, processing facilities, and 177 underground tanks containing 53 million gallons of highly radioactive and toxic liquids and sludge. New skills were needed by the workforce to accomplish this mission. By 1995, workers were in the process of getting the facilities in a safe condition and it became obvious improvements were needed in their tools, equipment and work practices. The Hanford ALARA Program looked good on paper, but did little to help contractors that were working in the field. The Radiological Control Director decided that the ALARA program needed to be upgraded and a significant improvement could be made if workers had a place they could visit that had samples of the latest technology and could talk to experienced personnel who have had success doing D and D work. Two senior health physics personnel who had many years experience in doing radiological work were chosen to obtain tools and equipment from vendors and find a location centrally located on the Hanford site. Vendors were asked to loan their latest tools and equipment for display. Most vendors responded and the Hanford ALARA Center of Technology opened on October 1, 1996. Today, the ALARA Center includes a classroom for conducting training and a mockup area with gloveboxes. Two large rooms have a containment tent, several glove bags, samples of fixatives/expandable foam, coating displays, protective clothing, heat stress technology, cutting tools, HEPA filtered vacuums, ventilation units, pumps, hydraulic wrenches, communications equipment, shears, nibblers, shrouded tooling, and several examples of innovative tools developed by the Hanford facilities. See Figures I and

Sintering with a chemical reaction as applied to uranium monocarbide; Frittage-reaction dans le cas du monocarbure d'uranium

Energy Technology Data Exchange (ETDEWEB)

Accary, A; Caillat, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

The present paper provides a survey of different investigations whose aim was the preparation and fabrication of uranium monocarbide for nuclear use. If a chemical reaction takes place in the sample during the sintering operation, it may be expected that the atom rearrangements involved in this reaction should favour the sintering process and thereby lower the temperature needed to yield a body of a given density. With this hypothesis in mind, the following methods have been studied: - Sintering of U-C mixtures; - Sintering of UO{sub 2}-C mixtures; - Hot pressing of U-C mixtures; - Extrusion of U-C mixtures. To generalize our result, it could be said that a chemical reaction does not lead to high densification, if one depends on a simple contact between discrete particles. On the contrary, a chemical reaction can help sintering if, as our hot pressing experiments shows, the densification can be achieved prior to the reaction. (author) [French] Le present article resume les etudes faites pour le compte du Commissariat a l'Energie Atomique dans le but de preparer du monocarbure d'uranium pour usage nucleaire. Si, en meme temps que l'on fritte une poudre, celle-ci est le siege d'une reaction chimique, on peut s'attendre a ce que le rearrangement atomique d'une reaction chimique favorise le frittage et, ainsi abaisse la temperature de travail necessaire pour obtenir une densite donnee. Nous avons etudie les methodes suivantes: - frittage des melanges U-C; - frittage des melanges UO{sub 2}-C; - frittage sous charge des melanges U-C; - filage des melanges U-C. Nos resultats montrent qu'une reaction chimique en cours de frittage ne conduit pas a un produit de haute densite si on opere sur un melange de poudres. Par contre, elle permet d'atteindre de hautes densites si la densification peut etre obtenue avant la reaction chimique. (auteur)

Measurement of the Quasifree pn → dη Reaction near Threshold

International Nuclear Information System (INIS)

Calen, H.; Dyring, J.; Fransson, K.; Gustafsson, L.; Haeggstroem, S.; Hoeistad, B.; Johansson, A.; Johansson, T.; Kullander, S.; Moertsell, A.; Ruber, R.J.; Schuberth, U.; Zlomanczuk, J.; Ekstroem, C.; Kilian, K.; Oelert, W.; Renken, V.; Sefzick, T.; Bondar, A.; Kuzmin, A.; Shwartz, B.; Sidorov, V.; Sukhanov, A.; Kupsc, A.; Marciniewski, P.; Stepaniak, J.; Dunin, V.; Morosov, B.; Povtorejko, A.; Sukhanov, A.; Zernov, A.; Zabierowski, J.; Wilhelmi, Z.

1997-01-01

The quasifree p+n→d+η reaction cross section has been measured in the near-threshold region using deuterium from an internal cluster-jet target and 1350 MeV protons in the CELSIUS storage ring of the The Svedberg Laboratory, Uppsala. The energy dependence of the cross section is extracted by exploiting the Fermi momentum of the target neutron and reconstructing the kinematics on an event-by-event basis. The data cover center of mass excess energies from 16 to 113 MeV. copyright 1997 The American Physical Society

Search strange (S = -2) dibaryons in the reaction K-+d->K++MM at 1,4 GeV/c

International Nuclear Information System (INIS)

D'Agostini, G.; Auriemma, G.; Marini, G.; Martellotti, G.; Massa, F.; Nigro, A.; Rambaldi, A.; Sciubba, A.

1982-01-01

The reaction K - + d -> K + + MM has been studied at 1.4 GeV/c, to search for Q = -1, S = -2 dibaryonic states, in the mass range approx.= 2.1-2.5 GeV/c 2 . No evidence for the presence of structures has been found and upper limits for the backward production differential cross section for narrow states are established. (orig.)

The reaction π+ + d = 2p in the 300 MeV range

International Nuclear Information System (INIS)

Braun, M.A.; Suslov, V.M.; Kallies, W.

1977-01-01

The inelastic pion deuteron scattering is studied for pion impulses in the centre-of-mass system at 50 to 300 MeV/c and polarization effects in the reaction p + p = π + + d for the case of polarized protons are analyzed too. A detailed comparison with experiments is given. (author)

Protein sequences and redox titrations indicate that the electron acceptors in reaction centers from heliobacteria are similar to Photosystem I

Science.gov (United States)

Trost, J. T.; Brune, D. C.; Blankenship, R. E.

1992-01-01

Photosynthetic reaction centers isolated from Heliobacillus mobilis exhibit a single major protein on SDS-PAGE of 47 000 Mr. Attempts to sequence the reaction center polypeptide indicated that the N-terminus is blocked. After enzymatic and chemical cleavage, four peptide fragments were sequenced from the Heliobacillus mobilis apoprotein. Only one of these sequences showed significant specific similarity to any of the protein and deduced protein sequences in the GenBank data base. This fragment is identical with 56% of the residues, including both cysteines, found in highly conserved region that is proposed to bind iron-sulfur center Fx in the Photosystem I reaction center peptide that is the psaB gene product. The similarity to the psaA gene product in this region is 48%. Redox titrations of laser-flash-induced photobleaching with millisecond decay kinetics on isolated reaction centers from Heliobacterium gestii indicate a midpoint potential of -414 mV with n = 2 titration behavior. In membranes, the behavior is intermediate between n = 1 and n = 2, and the apparent midpoint potential is -444 mV. This is compared to the behavior in Photosystem I, where the intermediate electron acceptor A1, thought to be a phylloquinone molecule, has been proposed to undergo a double reduction at low redox potentials in the presence of viologen redox mediators. These results strongly suggest that the acceptor side electron transfer system in reaction centers from heliobacteria is indeed analogous to that found in Photosystem I. The sequence similarities indicate that the divergence of the heliobacteria from the Photosystem I line occurred before the gene duplication and subsequent divergence that lead to the heterodimeric protein core of the Photosystem I reaction center.

Nucleon transfer reactions in D.W.B.A; Les reactions de transfert d'un nucleon dans la D.W.B.A

Energy Technology Data Exchange (ETDEWEB)

Giraud, B.; Picard, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-08-01

The DWBA for one nucleon transfer reaction is described as simply and completely as possible to show the possibilities and limits of this method. The extraction of spectroscopic factors is described in the appendix. (authors) [French] Le formalisme de la DWBA est decrit d'une maniere aussi simple et complete que possible pour mettre en evidence les possibilites et les limites de cette methode d'analyse des reactions de transfert. L'extraction des facteurs spectroscopiques est exposee en appendice. (auteurs)

Center of gravity estimation using a reaction board instrumented with fiber Bragg gratings

Science.gov (United States)

Oliveira, Rui; Roriz, Paulo; Marques, Manuel B.; Frazão, Orlando

2018-03-01

The purpose of the present work is to construct a reaction board based on fiber Bragg gratings (FBGs) that could be used for estimation of the 2D coordinates of the projection of center of gravity (CG) of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object's CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed.

Studies of nuclear reaction at very low energies

International Nuclear Information System (INIS)

Cecil, F.E.

1992-01-01

The deuteron radiative capture reactions on 2 H, 6 Li and 10 B have been measured between center of mass energies of 20 and 140 keV. Of note is the observation that the gamma ray-to-charged particle branching ratio for the DD reaction appears independent of energy down to a center of mass energy of 20 keV, consistent with some and contrary to other theoretical models. We have investigated the ratio of the reactions D(d,p)T and D(d,n) 3 He down to c.m. energies of 3 keV and the ratio of the reactions 6Li(d,p) 7 Li and 6 LI(d,α) 4 He down to a c.m. energy of 19 keV. The DD reaction ratio is independent of energy while the (d,p) branch of the D- 6 Li evinces a significant enhancement at the lowest measured energies. We have continued our investigation of charged particle production from deuterium-metal systems at a modest level of activity. Noteworthy in this investigation is the observation of 3 MeV protons from deuteron beam loaded Ti and LiD targets subjected to extreme thermal disequilibria. Significant facility improvements were realized during the most recent contract period. Specifically the downstream magnetic analysis system proposed to eliminate beam induced contaminants has been installed and thoroughly tested. This improvement should allow the D(a,γ) 6 Li reaction to be measured in the coming contract period. A scattering chamber required for the measurement of the 7 Li( 3 He,p) 9 Be reaction has been designed, fabricated and installed on the accelerator. A CAMAC based charged particle identification system has been assembled also for use in our proposed measurement of the 7 Li( 3 He, p) 9 Be

The yields of 1P and 1D resonances in the He(e,2e)He+ reaction

International Nuclear Information System (INIS)

Lhagva, O.; Badamdamdin, R.; Strakhova, S.I.; Hehnmedeh, L.

1991-01-01

In the first Born approximation the dependence of the yields of the 1 P and 1 D resonances in the He(e,2e)He + reaction on the momentum transfer in the recoil peak region at incident energies E 0 =1000 eV is studied. It is shown that in a certain range of the ejection angle and for the large momentum transfer the yield of the 1 D resonance dominates over the 1 P resonance one. 12 refs.; 4 figs

Low-energy d+d fusion reactions via the Trojan Horse Method

Energy Technology Data Exchange (ETDEWEB)

Tumino, A., E-mail: tumino@lns.infn.it [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Universita degli Studi di Enna ' Kore' , Enna (Italy); Spitaleri, C. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mukhamedzhanov, A.M. [Cyclotron Institute Texas A and M University, College Station, TX (United States); Typel, S. [Excellence Cluster Universe, Technische Universitaet Muenchen, Garching (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH - Theorie, Darmstadt (Germany); Aliotta, M. [School of Physics and Astronomy, University of Edinburgh, Edinburgh, Scotland (United Kingdom); Scottish Universities Physics Alliance (United Kingdom); Burjan, V. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Gimenez del Santo, M. [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Kiss, G.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); ATOMKI, Debrecen (Hungary); Kroha, V.; Hons, Z. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); La Cognata, M.; Lamia, L. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mrazek, J. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Pizzone, R.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Piskor, S. [Nuclear Physics Institute of ASCR, Rez (Czech Republic); Rapisarda, G.G.; Romano, S.; Sergi, M.L.; Sparta, R. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy)

2011-06-06

The bare nucleus S(E) factors for the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured for the first time via the Trojan Horse Method off the proton in {sup 3}He from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

Low-energy d+d fusion reactions via the Trojan Horse Method

International Nuclear Information System (INIS)

Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A.M.; Typel, S.; Aliotta, M.; Burjan, V.; Gimenez del Santo, M.; Kiss, G.G.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Mrazek, J.; Pizzone, R.G.; Piskor, S.; Rapisarda, G.G.; Romano, S.; Sergi, M.L.; Sparta, R.

2011-01-01

The bare nucleus S(E) factors for the 2 H(d,p) 3 H and 2 H(d,n) 3 He reactions have been measured for the first time via the Trojan Horse Method off the proton in 3 He from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4±1.8 MeVb for 3 H+p and 60.1±1.9 MeVb for 3 He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

Measurement of D(d,p)T Reaction Cross Sections in Sm Metal in Low Energy Region (10(≤) Ed(≤)20 keV)

Institute of Scientific and Technical Information of China (English)

WANG Tie-Shan; YANG Zhen; H. Yunemura; A. Nakagawa; LV Hui-Yi; CHEN Jian-Yong; LIU Sheng-Jin; J. Kasagi

2007-01-01

To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D{d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2 K for beam energies ranging from 10 to 20keV. The thick target yields of protons emitted in the D(d,p)T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2K is deduced to be 520±56eV. As compared with the value achieved in the gas target, the calculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section cr(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2K are obtained, respectively.

Model photo reaction centers via genetic engineering

Energy Technology Data Exchange (ETDEWEB)

Zhiyu Wang; DiMagno, T.J.; Popov, M.; Norris, J.R. [Argonne National Lab., IL (United States)]|[Chicago Univ., IL (United States). Dept. of Chemistry; Chikin Chan; Fleming, G. [Chicago Univ., IL (United States). Dept. of Chemistry; Jau Tang; Hanson, D.; Schiffer, M. [Argonne National Lab., IL (United States)

1992-12-31

A series of reaction centers of Rhodococcus capsulatus isolated from a set of mutated organisms modified by site-directed mutagenesis at residues M208 and L181 are described. Changes in the amino acid at these sites affect both the energetics of the systems as well as the chemical kinetics for the initial ET event. Two empirical relations among the different mutants for the reduction potential and the ET rate are presented.

Model photo reaction centers via genetic engineering

Energy Technology Data Exchange (ETDEWEB)

Zhiyu Wang; DiMagno, T.J.; Popov, M.; Norris, J.R. (Argonne National Lab., IL (United States) Chicago Univ., IL (United States). Dept. of Chemistry); Chikin Chan; Fleming, G. (Chicago Univ., IL (United States). Dept. of Chemistry); Jau Tang; Hanson, D.; Schiffer, M. (Argonne National Lab., IL (United States))

1992-01-01

A series of reaction centers of Rhodococcus capsulatus isolated from a set of mutated organisms modified by site-directed mutagenesis at residues M208 and L181 are described. Changes in the amino acid at these sites affect both the energetics of the systems as well as the chemical kinetics for the initial ET event. Two empirical relations among the different mutants for the reduction potential and the ET rate are presented.

New coordination polymers from 1D chain, 2D layer to 3D framework constructed from 1,2-phenylenediacetic acid and 1,3-bis(4-pyridyl)propane flexible ligands

International Nuclear Information System (INIS)

Xin Lingyun; Liu Guangzhen; Wang Liya

2011-01-01

The hydrothermal reactions of Cd, Zn, or Cu(II) acetate salts with H 2 PHDA and BPP flexible ligands afford three new coordination polymers, including [Cd(PHDA)(BPP)(H 2 O)] n (1), [Zn(PHDA)(BPP)] n (2), and [Cu 2 (PHDA) 2 (BPP)] n (3) (H 2 PHDA=1,2-phenylenediacetic acid, BPP=1,3-bis(4-pyridyl)propane). The single-crystal X-ray diffractions reveal that all three complexes feature various metal carboxylate subunits extended further by the BPP ligands to form a diverse range of structures, displaying a remarked structural sensitivity to metal(II) cation. Complex 1 containing PHDA-bridged binuclear cadmium generates 1D double-stranded chain, complex 2 results in 2D→2D interpenetrated (4,4) grids, and complex 3 displays a 3D self-penetrated framework with 4 8 6 6 8 rob topology. In addition, fluorescent analyses show that both 1 and 2 exhibit intense blue-violet photoluminescence in the solid state. - Graphical Abstract: We show diverse supramolecular frameworks based on the same ligands (PHDA and BPP) and different metal acetate salts including 1D double-stranded chain, 2D → 2D twofold interpenetrated layer, and 3D self-penetration networks. Highlights: → Three metal(II = 2 /* ROMAN ) coordination polymers were synthesized using H 2 PHDA and BPP. → The diversity of structures show a remarked sensitivity to metal(II) center. → Complexes show the enhancement of fluorescence compared to that of free ligand.

d-3He reaction measurements during fast wave minority heating in PLT

International Nuclear Information System (INIS)

Chrien, R.E.; Strachan, J.D.

1983-01-01

Time- and energy-resolved d- 3 He fusion reactions have been measured to infer the energy of the d + or He ++ minority ions heated near their cyclotron frequency by the magnetosonic fast wave. The average energy of the reacting 3 He ions during 3 He minority heating is in the range of 100 to 400 keV, as deduced from the magnitude of the reaction rate, its decay time, and the energy spread of the proton reaction products. The observed reaction rate and its scaling with wave power and electron density and temperature are in qualitative agreement with a radial reaction rate model using the minority distribution predicted from quasilinear velocity space diffusion. Oscillations in the reaction rate are observed concurrent with sawtooth and m = 2 MHD activity in the plasma

Stopped-flow studies of the reaction of D-tartronate semialdehyde-2-phosphate with human neuronal enolase and yeast enolase 1.

Science.gov (United States)

Brewer, John M; McKinnon, Jared S; Phillips, Robert S

2010-03-05

We determined the kinetics of the reaction of human neuronal enolase and yeast enolase 1 with the slowly-reacting chromophoric substrate D-tartronate semialdehyde phosphate (TSP), each in tris (tris (hydroxymethyl) aminomethane) and another buffer at several Mg2+ concentrations, 50 or 100 microM, 1 mM and 30 mM. All data were biphasic, and could be satisfactorily fit, assuming either two successive first-order reactions or two independent first-order reactions. Higher Mg2+ concentrations reduce the relative magnitude of the slower reaction. The results are interpreted in terms of a catalytically significant interaction between the two subunits of these enzymes. Copyright (c) 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Synthesis of novel steroid-tetrahydroquinoline hybrid molecules and D-homosteroids by intramolecular cyclization reactions.

Science.gov (United States)

Magyar, Angéla; Wölfling, János; Kubas, Melanie; Cuesta Seijo, Jose Antonio; Sevvana, Madhumati; Herbst-Irmer, Regine; Forgó, Péter; Schneider, Gyula

2004-05-01

Steroidal aryliminium salts were prepared from D-seco-pregnene aldehyde 2b, and their BF3.OEt2-catalyzed reactions were studied. The nature of the substituent R1 in the anilines 3-6 essentially influenced the chemoselectivity. Using unsubstituted 3, 4-methoxy- (4) or 4-bromoaniline (5), different tetrahydroquinoline derivatives 7a-13a via intramolecular hetero Diels-Alder reaction were formed. In the case of 4-nitroaniline (6) the N-arylamino-D-homopregnane (14a) were also obtained. We assume, that an intramolecular Prins reaction led to this type of fluoro-D-homosteroid. The main products represent a new class of tetrahydroquinolino-androstenes.

Isospin non-conservation in 14N(d,d')14N reaction

International Nuclear Information System (INIS)

Aoki, Y.; Sanada, J.; Yagi, K.; Kunori, S.; Higashi, Y.

1978-01-01

The deuteron inelastic scattering experiments on 14 N are made at E sub(d) = 10.03, 11.65, 14.82 and 17.88 MeV, laying an emphasis on the isospin-forbidden excitation of the 2.31 MeV (0 + , T = 1) state. In order to clarify the reaction mechanism, we have performed analyses assuming both the direct reaction mechanism and the compound nucleus formation. For the above isospin-forbidden transition, the calculation in the second-order DWBA which assumes the isospin mixing in the intermediate channels, reproduces fairly well the strong energy dependence of the angular distribution and the cross section. For the isospin-allowed transition the simple DWBA calculation gives reasonable agreement with the experiment. The present calculation shows that the observed isospin violation is well accounted for by the direct multi-step reaction mechanism assuming the isospin mixing in the intermediate channels. (author)

N{sub 33}{sup *++} isobar production and isospin 2 {pi}{pi} interaction studied in the reaction {pi}{sup -} p {yields} p {pi}{sup +}{pi}{sup -}{pi}{sup -} at 2.75 GeV/c; Production de l'isobare N{sub 33}{sup *++} et interaction {pi}{pi} dans l'etat d'isospin I = 2, etudiees dans la reaction {pi}{sup -} p {yields} p {pi}{sup +}{pi}{sup -}{pi}{sup -} a 2.75 GeV/c

Energy Technology Data Exchange (ETDEWEB)

Alitti, J [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

1967-07-01

A study of the reaction {pi}{sup -} p {yields} p {pi}{sup +}{pi}{sup -}{pi}{sup -} at 2.75 GeV/c was carried out in an 81 cm liquid hydrogen bubble chamber at the CERN proton synchrotron. One observes that the abundant N{sub 33}{sup *++} (1236 MeV) isobar production occurs predominantly backwards in the center of mass of the reaction. This feature suggests a peripheral production mechanism with {pi} exchange. The validity of this hypothesis, which allows the study of the {pi}{sup -}{pi}{sup -} interaction within the frame of the Chew and Low model, is verified. Among other results one finds for the isospin-2 state the values of the elastic {pi}{pi} cross section and of the S and D wave phase shifts. (author) [French] Etude de la reaction {pi}{sup -} p {yields} p {pi}{sup +}{pi}{sup -}{pi}{sup -} a 2.75 GeV/c, effectuee a l'aide de la chambre a bulles a hydrogene liquide de 81 cm de Saclay exposee aupres du synchrotron a protons du CERN. On observe une abondante production de l'isobare N{sub 33}{sup *++} a 1236 MeV, lequel est emis de preference vers l'arriere dans le centre de masse de la reaction. Ceci suggere un mecanisme de production peripherique avec echange d'un {pi}. Cette hypothese dont on a mis a l'epreuve la validite permet l'etude de l'interaction {pi}{sup -}{pi}{sup -} dans le cadre du modele de Chew et Low. Entre autres resultats, on donne, pour l'etat d'isospin I = 2, les valeurs de la section efficace de diffusion elastique {pi}{pi} et les dephasages des ondes S et D. (auteur)

Spectroscopic factors measurements in the s,d and f,p shells below and above the Coulomb barrier by (3He,d) reactions

International Nuclear Information System (INIS)

Baghdadi, Ahmed.

1974-01-01

The overlap of t and d or 3 He and d wave functions may be measured by one neutron transfer in (d,t) or one proton transfer in ( 3 He,d). The measurement of the resulting normalization constant has been performed in subcoulombic conditions in the case of 58 Ni( 3 He,d) 59 Cu and 60 Ni( 3 He,d) 61 Cu leading to the first 3/2 - and 1/2 - states with a position sensitive detector in a Buechner spectrograph. The result: D 2 =2.7+-0.2 10 4 MeV 2 fm 3 is in agreement with the D 2 measurement for (t,d) reactions [3.1+-0.2 10 4 MeV 2 fm 3 ] and with the theoretical value proposed by L.J.B. Goldfarg and coworkers. This result was used for a determination of the spectroscopic factors of the 1.379MeV 3/2 - state, the 1.507MeV 1/2 - state and the 1.758MeV 3/2 - state in 57 Co. The subcoulombic approximation is also shown to be valid even in the case of (d,p) reactions, by the measurement of angular distributions and excitation curves of 60 Ni(d,p) reactions leading to the excited states at 4.760MeV (l=2) and 4.907MeV (l=0). In the second part, some spectroscopic factors in the s-d shell were measured by ( 3 He,d) reactions at MP Tandem energies. In the case of 27 Al( 3 He,d) 28 Si (states at 4.62, 6.88, 6.89, 9.32 and 0.38MeV) the normalization constant D 0 2 (deduced from the subcoulombic D 2 value) together with the first order finite range approximation leads to spectroscopic factors in good agreement with Wildenthal theoretical results. For 28 Si( 3 He,d) 29 p however, the values are too high compared to 29 Si. The conclusion is that it is better to use the DWBA treatment at subcoulombic energies everytime the experimental conditions may be fulfilled [fr

Hydrogen bonds in the vicinity of the special pair of the bacterial reaction center probed by hydrostatic high-pressure absorption spectroscopy.

Science.gov (United States)

Kangur, Liina; Jones, Michael R; Freiberg, Arvi

2017-12-01

Using the native bacteriochlorophyll a pigment cofactors as local probes, we investigated the response to external hydrostatic high pressure of reaction center membrane protein complexes from the photosynthetic bacterium Rhodobacter sphaeroides. Wild-type and engineered complexes were used with a varied number (0, 1 or 2) of hydrogen bonds that bind the reaction center primary donor bacteriochlorophyll cofactors to the surrounding protein scaffold. A pressure-induced breakage of hydrogen bonds was established for both detergent-purified and membrane-embedded reaction centers, but at rather different pressures: between 0.2 and 0.3GPa and at about 0.55GPa, respectively. The free energy change associated with the rupture of the single hydrogen bond present in wild-type reaction centers was estimated to be equal to 13-14kJ/mol. In the mutant with two symmetrical hydrogen bonds (FM197H) a single cooperative rupture of the two bonds was observed corresponding to an about twice stronger bond, rather than a sequential rupture of two individual bonds. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrostatic dominoes: long distance propagation of mutational effects in photosynthetic reaction centers of Rhodobacter capsulatus.

Science.gov (United States)

Sebban, P; Maróti, P; Schiffer, M; Hanson, D K

1995-07-04

Two point mutants from the purple bacterium Rhodobacter capsulatus, both modified in the M protein of the photosynthetic reaction center, have been studied by flash-induced absorbance spectroscopy. These strains carry either the M231Arg --> Leu or M43ASN --> Asp mutations, which are located 9 and 15 A, respectively, from the terminal electron acceptor QB. In the wild-type Rb. sphaeroides structure, M231Arg is involved in a conserved salt bridge with H125Glu and H232Glu and M43Asn is located among several polar residues that form or surround the QB binding site. These substitutions were originally uncovered in phenotypic revertants isolated from the photosynthetically incompetent L212Glu-L213Asp --> Ala-Ala site-specific double mutant. As second-site suppressor mutations, they have been shown to restore the proton transfer function that is interrupted in the L212Ala-L213Ala double mutant. The electrostatic effects that are induced in reaction centers by the M231Arg --> Leu and M43Asn --> Asp substitutions are roughly the same in either the double-mutant or wild-type backgrounds. In a reaction center that is otherwise wild type in sequence, they decrease the free energy gap between the QA- and QB- states by 24 +/- 5 and 45 +/- 5 meV, respectively. The pH dependences of K2, the QA-QB QAQB- equilibrium constant, are altered in reaction centers that carry either of these substitutions, revealing differences in the pKas of titratable groups compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

An Experimental and Theoretical Study on the Kinetic Isotope Effect of C2H6 and C2D6 Reaction with OH

KAUST Repository

Khaled, Fathi; Giri, Binod; Szőri, Milá n; Viskolcz, Bé la; Farooq, Aamir

2015-01-01

We report experimental and theoretical results for the deuterated kinetic isotope effect (DKIE) of the reaction of OH with ethane (C2H6) and deuterated ethane (C2D6). The reactions were investigated behind reflected shock waves over 800–1350 K by monitoring OH radicals near 306.69 nm using laser absorption. In addition, high level CCSD(T)/cc-pV(T,Q)Z//MP2/cc-pVTZ quantum chemical and statistical rate theory calculations were performed which agreed very well with the experimental findings. The results reported herein provide the first experimental evidence that DKIE for alkanes asymptotes to a value of 1.4 at high temperatures.

An Experimental and Theoretical Study on the Kinetic Isotope Effect of C2H6 and C2D6 Reaction with OH

KAUST Repository

Khaled, Fathi

2015-10-30

We report experimental and theoretical results for the deuterated kinetic isotope effect (DKIE) of the reaction of OH with ethane (C2H6) and deuterated ethane (C2D6). The reactions were investigated behind reflected shock waves over 800–1350 K by monitoring OH radicals near 306.69 nm using laser absorption. In addition, high level CCSD(T)/cc-pV(T,Q)Z//MP2/cc-pVTZ quantum chemical and statistical rate theory calculations were performed which agreed very well with the experimental findings. The results reported herein provide the first experimental evidence that DKIE for alkanes asymptotes to a value of 1.4 at high temperatures.

Probing the Energy Transfer Dynamics of Photosynthetic Reaction Center Complexes Through Hole-Burning and Single-Complex Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Riley, Kerry Joseph [Iowa State Univ., Ames, IA (United States)

2007-01-01

Photosynthesis is the process by which light energy is used to drive reactions that generate sugars to supply energy for cellular processes. It is one of the most important fundamental biological reactions and occurs in both prokaryotic (e.g. bacteria) and eukaryotic (e.g. plants and algae) organisms. Photosynthesis is also remarkably intricate, requiring the coordination of many different steps and reactions in order to successfully transform absorbed solar energy into a biochemical usable form of energy. However, the net reaction for all photosynthetic organisms can be reduced to the following, deceptively general, equation developed by Van Niel[1] H₂ - D + A_implies^hv A - H₂ + D where H₂-D is the electron donor, e.g. H₂O, H₂S. A is the electron acceptor, e.g. CO₂, and A-H₂ is the synthesized sugar. Amazingly, this simple net equation is responsible for creating the oxidizing atmosphere of Earth and the recycling of CO₂, both of which are necessary for the sustainment of the global ecosystem.

A multi-pathway model for photosynthetic reaction center

International Nuclear Information System (INIS)

Qin, M.; Shen, H. Z.; Yi, X. X.

2016-01-01

Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

The 91Zr(d,t)90Zr reaction

International Nuclear Information System (INIS)

Gomes, L.C.

1975-01-01

Sixteen levels populated in the 91 Zr(d,t) 90 Zr pick-up reaction were studied with 16 MeV deuterons. Distorted waves Born approximation calculations were compared to the data, and yielded spectroscopic factors and l values. Particle-hole states in 90 Zr were observed. Some significant errors were found in Zr(d,t) reactions Q values recently compiled [pt

Conversion of 2-deoxy-D-ribose into 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)pyridine, 2'-deoxypseudouridine, and other C-(2'-deoxyribonucleosides).

Science.gov (United States)

Reese, Colin B; Wu, Qinpei

2003-09-21

The synthesis of 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)pyridine 2a, 2-amino-5-(2-deoxy-alpha-D-ribofuranosyl)-pyridine 23, 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)-3-methylpyridine 2b, 2-amino-5-(2-deoxy-alpha-D-ribofuranosyl)-3-methylpyridine 29 and 5-(2-deoxy-beta-D-ribofuranosyl)-2,4-dioxopyrimidine [2'-deoxypseudouridine] 30a is described. These C-nucleosides are prepared either from 2-deoxy-3,5-O-(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-D-ribofuranose 15 or from 2-deoxy-3,5-O-(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-D-ribono-1,4-lactone 16, which are themselves prepared from 2-deoxy-D-ribose 13. The sugar derivatives are first allowed to react with the appropriate 5-lithio-pyridine or 5-lithio-pyrimidine derivatives, which are prepared from 5-bromo-2-(dibenzylamino)pyridine 12a, 5-bromo-2-[bis(4-methoxybenzyl)amino]pyridine 12b, 5-bromo-2-dibenzylamino-3-methylpyridine 25 and 5-bromo-2,4-bis(4-methoxybenzyloxy)pyrimidine 33. The products from the reactions between the lithio-derivatives and the lactol 15 are cyclized under Mitsunobu conditions; the products from the reactions between the lithio-derivatives and the lactone 16 are first reduced with L-Selectride before cyclization, also under Mitsunobu conditions. In all cases, the beta-anomers of the protected C-nucleosides are the predominant products. Finally, the separation of the alpha- and beta-anomers and the removal of all of the protecting groups are described.

Total cross-section measurements on aluminium, carbon, fluorine and hydrogen for d, d reaction neutrons using the coincidence method (1963); Mesure de la section efficace totale de l'aluminium, du carbone, du fluor et de l'hydrogene pour des neutrons de la reaction d, d par la methode des coincidences (1963)

Energy Technology Data Exchange (ETDEWEB)

Ambrosino, G; Sorriaux, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The experiment described consists in the measurement of the total cross-section of various materials: aluminium, carbon, fluorine and hydrogen, for mono-energetic 2.77 MeV neutrons obtained from the d,d reaction. The measurement is carried out by transmission. The neutrons are detected by means of a plastic scintillator mounted on a 56 AVP photomultiplier, and are isolated from all secondary phenomena (background noise, scattered neutrons) by coincidence with helium 3. which particles are associated to the neutrons from the reaction {sup 2}{sub 1}D ({sup 2}{sub 1}D, n) {sup 3}{sub 2}H The helium 3 particles are detected by a PN junction diode used with inverted polarisation. An absorption exponential has been traced out using measurements made on seven aluminium bars. The accuracy of the total cross-section measurements is about 10{sup -2}. (authors) [French] L'experience exposee dans ce rapport consiste en la mesure des sections efficaces totales de differents materiaux: aluminium, carbone, fluor et hydrogene, pour des neutrons monoenergetiques de 2,77 MeV, obtenus par la reaction d,d. La mesure est faite par transmission. Les neutrons sont detectes par un scintillateur plastique monte sur un photomultiplicateur 56 AVP, et sont separes de tout phenomene secondaire (bruit de fond, neutrons diffuses) par coincidence avec les helium 3, particules associees aux neutrons de la reaction {sup 2}{sub 1}D ({sup 2}{sub 1}D, n) {sup 3}{sub 2}H Les helium 3 sont detectes par une diode a jonction PN utilisee en polarisation inverse. Une exponentielle d'absorption a ete tracee a partir de mesures faites sur sept barreaux d'aluminium. La precision des mesures des sections efficaces totales est de l'ordre de 10{sup -2}. (auteurs)

Effects of Boreal Lake Wetlands on Atmospheric 13CH3D and 12CH2D2

Science.gov (United States)

Haghnegahdar, M. A.; Kohl, I. E.; Schauble, E. A.; Walter Anthony, K. M.; Young, E. D.

2017-12-01

Recently, we developed a theoretical model to investigate the potential use of 13CH3D and 12CH2D2 as tools for tracking atmospheric methane budget. We used electronic structure methods to estimate kinetic isotope fractionations associated with the major sink reactions of CH4 in air (reactions with •OH and Cl•), and literature data with reconnaissance measurements of the relative abundances of 13CH3D and 12CH2D2 to estimate the compositions of the largest atmospheric sources. Here we present new methane rare isotopologue data from boreal wetlands, comprising one of the most important sources, in order to evaluate the robustness of the model. Boreal wetlands (>55° N) account for more than half of the wetland area in the Northern hemisphere. We analyzed methane samples from high latitude lakes representing different geographical regions, geological and ecological contexts, methane fluxes, and isotopic signatures. Using clumped isotopes of CH4 we are able to determine the likely production mechanism for natural CH4 samples. So far, all of our analyzed samples except one plot in the microbial pure-culture methanogenesis field (Young et al. 2017) with ranges of -0.2‰ to +1.2‰ for Δ13CH3D, and -29.6‰ to -18.2‰ for Δ12CH2D2. These compositions are far from equilibrium. The one exception, from Lake Doughnut, Alaska, exhibits Δ13CH3D and Δ12CH2D2 values of +5.2‰ and +18.7‰, respectively, which fall near ambient thermodynamic equilibrium values. This may be an effect of methanotrophy. Mean Δ13CH3D and Δ12CH2D2 for all lake samples are +1.7‰ and -15.4‰ respectively, compared to our original estimate of +6.1‰ and +21.2‰ for the wetland methane source based on an assumption of equilibrium. If we assume that these samples are representative of the overall wetland source, Δ13CH3D decreases by 0.8‰ and Δ12CH2D2 decreases by 0.6‰ in our model of bulk atmospheric methane. Δ13CH3D and Δ12CH2D2 values of air (including •OH and Cl• sink

Development of D-allose sensor on the basis of three strategic enzyme reactions.

Science.gov (United States)

Miyanishi, Nobumitsu; Nakakita, Shin-Ichi; Sumiyoshi, Wataru; Okuma, Hirokazu; Izumori, Ken; Hirabayashi, Jun

2010-09-15

Rare sugars are defined as monosaccharides and their derivatives that rarely exist in nature, according to the International Society of Rare Sugars. D-Allose (3-epi d-glucose) is one of the rare sugars, for which various physiological activities have recently been found, with increasing attention to its applications to bio-industry. Until now, however, there is no convenient method of measuring these sugars in a specific manner. For detecting D-allose, three consecutive enzyme reactions were devised by fabricating of a reaction batch chamber packed with L-rhamnose isomerase (LRI), D-tagatose 3-epimerase (DTE) and a screen-printed electrode, on which D-fructose dehydrogenase (DFDH) was immobilized. To obtain a substantial sensing system, extensive experimental parameters were optimized. These included the concentration of photo-crosslinkable poly (vinyl alcohol) bearing stilbazolium groups (PVA-SbQ), reaction ratios, and temperature of the batch chamber. By adopting the three consecutive enzyme reactions, an undesirable reverse reaction was minimized. As a result, the developed sensor system exhibited a good linear response on D-allose in the range from 0.1 to 50 mM (r(2)=0.998). The system has an apparent advantage over the previous chromatography approach in terms of simplicity and inexpensiveness. Copyright 2010 Elsevier B.V. All rights reserved.

Study of hyperon-nucleon interactions with d(e,e'K) reactions

International Nuclear Information System (INIS)

Lee, T.-S. H.

1998-01-01

The dependence of the d(e,eprimeK + ) reaction cross sections on the hyperon-nucleon interactions is investigated. It is shown that the data obtained with Longitudinal-Transverse separation or polarized photons can distinguish a class of Nijmegen models of hyperon-nucleon interactions which are χ 2 -equivalent in fitting the existing 35 data points of hyperon-nucleon reactions

Geometric phase and quantum interference in photosynthetic reaction center: Regulation of electron transfer

Energy Technology Data Exchange (ETDEWEB)

Sun, Yuming, E-mail: ymsun@ytu.edu.cn; Su, Yuehua; Dai, Zhenhong; Wang, WeiTian

2016-10-20

Photosynthesis is driven by electron transfer in reaction centers in which the functional unit is composed of several simple molecules C{sub 2}-symmetrically arranged into two branches. In view of quantum mechanism, both branches are possible pathways traversed by the transferred electron. Due to different evolution of spin state along two pathways in transmembrane electric potential (TEP), quantum state of the transferred electron at the bridged site acquires a geometric phase difference dependent on TEP, the most efficient electron transport takes place in a specific range of TEP beyond which electron transfer is dramatically suppressed. What’s more, reaction center acts like elaborately designed quantum device preparing polarized spin dependent on TEP for the transferred electron to regulate the reduction potential at bridged site. In brief, electron transfer generates the TEP, reversely, TEP modulates the efficiency of electron transfer. This may be an important approach to maintaining an appreciable pH environment in photosynthesis.

Reactions of 3d-series metallocenes with organic cadmium compounds

International Nuclear Information System (INIS)

Razuvaev, G.A.; Mar'in, V.P.; Vyshinskaya, L.I.; Grinval'd, I.I.; Spiridonova, N.N.

1987-01-01

Interaction of organic cadmium compounds and 3d-series metallocenes, Cp 2 M (M=V, Cr, Mn, Ni, Co) has been studied. It is shown that direction of these reactions is determined by metallocene nature. Reactions of oxidizing addition leading to σ-complexes formation are characteristic for vanadium and chromium metallocenes. When reacting cobaltocene with R 2 Cd, R group introduction to cyclopentadienyl ring and elimination of cobalt diene complexes take place. Manganocene and nickelocene interaction goes through the stage of complex formation with transition metal - cadmium bond

Hole centers in γ-irradiated, oxidized Al2O3

International Nuclear Information System (INIS)

Lee, K.H.; Holmberg, G.E.; Crawford, J.H. Jr.

1976-01-01

ESR observations of centers with S = 1/2, g approximately equal to 2, S = 1, g approximately equal to 2 have been made at 77 K on oxidized Al 2 O 3 after γ-irradiation at 30 0 C. From the radiation growth data, it is shown that the S = 1/2 centers are precursors of the S = 1 centers. In addition, when the S = 1 centers anneal out at about 110 0 C, the S = 1/2 centers reappear and eventually anneal out at about 260 0 C. Previously Gamble (Gamble, F.T.; Ph.D. Thesis, U. of Connecticut (1963)) and Cox (Cox, R.T.; Ph.D. Thesis, U. of Grenoble (1972) unpublished), respectively, observed S = 1/2 and S = 1 paramagnetic centers in electron-irradiated nominally pure Al 2 O 3 and γ-irradiated, oxidized, titanium-doped Al 2 O 3 . The models proposed for these centers were one hole and two holes trapped on oxygen ions adjacent to Al 3+ vacancies. Our results further substantiate these models. (author)

Final results for the excitation function and angular distributions of the 3H(d,n)4He reaction

International Nuclear Information System (INIS)

Tang Hongqing; Zhou Zuying; Qi Bujia; Zhou Chenwei; Du Yanfeng; Xia Haihong; Chen Zemin; Chen Zhenpeng; Chen Yingtang

1998-01-01

The final relative excitation function of the 3 H(d,n) 4 He rection at 0 degree is shown out. For comparison, a curve calculated from Drosg's HI-13 tandem is in progressplotted. The angular distributions of the 3 H(d,n) 4 He reaction at E d =13.36, 16.50 and 19.50 Mev in the center-of-mass system are shown out. A comparison of the legendre polynomial coefficients obtained from the present angular distribution data with Drosg's evaluation are reported

Indirect Study of the (2)H(d,p)(3)H and (2)H(d,n)(3)He Reactions at Astrophysical Energies via the Trojan Horse Method

Czech Academy of Sciences Publication Activity Database

Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A.; Typel, S.; Aliotta, M.; Burjan, Václav; Del Santo, M. G.; Kiss, G.G.; Kroha, Václav; Hons, Zdeněk; La Cognata, M.; Lamia, L.; Mrázek, Jaromír; Pizzone, R. G.; Piskoř, Štěpán; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Sparta, R.

2011-01-01

Roč. 50, 1-4 (2011), s. 323-325 ISSN 0177-7963. [21st European Conference on Few-Body Problems in Physics Location. Salamanca, 30.08.2010-03092010] R&D Projects: GA ČR GAP203/10/0310 Institutional research plan: CEZ:AV0Z10480505 Keywords : CROSS-SECTIONS * REACTION-RATES * COMPILATION * D+D Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.438, year: 2011

Low-Temperature Experimental and Theoretical Rate Constants for the O(1D) + H2 Reaction.

Science.gov (United States)

Hickson, Kevin M; Suleimanov, Yury V

2017-03-09

In the present joint experimental and theoretical study, we report thermal rate constants for the O( 1 D) + H 2 reaction within the 50-300 K temperature range. Experimental kinetics measurements were performed using a continuous supersonic flow reactor coupled with pulsed laser photolysis for O( 1 D) production and pulsed laser-induced fluorescence in the vacuum ultraviolet wavelength range (VUV LIF) for O( 1 D) detection. Theoretical rate constants were obtained using the ring polymer molecular dynamics (RPMD) approach over the two lowest potential energy surfaces 1 1 A' and 1 1 A″, which possess barrierless and thermally activated energy profiles, respectively. Both the experimental and theoretical rate constants exhibit a weak temperature dependence. The theoretical results show the dominant role of the 1 1 A' ground state and that contribution of the 1 1 A″ excited state to the total thermal rate decreases dramatically at lower temperature. Agreement between the experimental and theoretical results is good, and the discrepancy does not exceed 25%. It is argued that these differences are likely to be due to nonadiabatic couplings between the 1 1 A' and 2 1 A' surfaces.

Measurement of the D(n,2n)p reaction cross section up to 30 MeV

Energy Technology Data Exchange (ETDEWEB)

Laborie, J.M.; Ledoux, X.; Varignon, C.; Lazauskas, R.; Morillon, B.; Belier, G.; Arnal, N. [CEA Bruyeres-le-Chatel (DPTA/SPN), 91 (France). Dept. de Physique Theorique et Appliquee; Dore, D. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee (DAPNIA/SPhN), 91- Gif sur Yvette (France)

2008-07-01

This article presents a running experimental program to measure the neutron-induced deuteron break-up reaction between 5 and 10 MeV, and between 20 and 30 MeV. The measurements are performed with a C{sub 6}D{sub 6} detector as deuteron target placed in a beam line of the Tandem 7 MV accelerator in Cea facilities, dedicated to the use of a 4{pi} neutron detector which allows us to measure the two emitted neutrons. The total uncertainty is evaluated from 8.5 to 11 per cent. This experimental work is done in parallel with an ab-initio calculation of the reaction which is sum up in the text. Comparisons to the measured cross section are done together with CENDL2 and Endf/B-VII evaluations. (authors)

Measurement of the D(n,2n)p reaction cross section up to 30 MeV

International Nuclear Information System (INIS)

Laborie, J.M.; Ledoux, X.; Varignon, C.; Lazauskas, R.; Morillon, B.; Belier, G.; Arnal, N.

2008-01-01

This article presents a running experimental program to measure the neutron-induced deuteron break-up reaction between 5 and 10 MeV, and between 20 and 30 MeV. The measurements are performed with a C 6 D 6 detector as deuteron target placed in a beam line of the Tandem 7 MV accelerator in Cea facilities, dedicated to the use of a 4π neutron detector which allows us to measure the two emitted neutrons. The total uncertainty is evaluated from 8.5 to 11 per cent. This experimental work is done in parallel with an ab-initio calculation of the reaction which is sum up in the text. Comparisons to the measured cross section are done together with CENDL2 and Endf/B-VII evaluations. (authors)

Thermodynamics of the hydrolysis reactions of α-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4-nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate

International Nuclear Information System (INIS)

Goldberg, Robert N.; Lang, Brian E.; Lo, Catherine; Ross, David J.; Tewari, Yadu B.

2009-01-01

Microcalorimetry, high-performance liquid chromatography (h.p.l.c.), and an enzymatic assay have been used to conduct a thermodynamic investigation of five phosphate hydrolysis reactions: {α-D-galactose 1-phosphate(aq) + H 2 O(l) = D-galactose(aq) + orthophosphate(aq)} (1), {sn-glycerol 3-phosphate(aq) + H 2 O(l) = glycerol(aq) + orthophosphate(aq)} (2), {4-nitrophenyl phosphate(aq) + H 2 O(l) = 4-nitrophenol(aq) + orthophosphate(aq)} (3), {phosphocreatine(aq) + H 2 O(l) = creatine(aq) + orthophosphate(aq)} (4), and {3-phospho-D-glycerate(aq) + H 2 O(l) = D-glycerate(aq) + orthophosphate(aq)} (5). Calorimetrically determined enthalpies of reaction Δ r H(cal) were measured for reactions (1)-(5) and the apparent equilibrium constant K' was measured for reaction (2). The pKs and standard enthalpies of reaction Δ r H 0 for the H + and Mg 2+ binding reactions of the reactants and products in the aforementioned reactions were obtained either from the literature or by estimation. A chemical equilibrium model was then used to calculate standard equilibrium constants K and standard enthalpies of reaction Δ r H 0 for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. Property values from the literature and thermodynamic network calculations were used to obtain values of the equilibrium constants for the chemical reference reactions that correspond to the overall biochemical reactions (1). These values were compared with other results from the literature and also correlated with structural features. The results obtained in this study can be used in the chemical equilibrium model to calculate values of K', the standard apparent Gibbs free energy changes Δ r G '0 , the standard apparent enthalpy changes Δ r H '0 , changes in binding of the proton Δ r N(H + ), and the position of equilibrium for the overall biochemical reactions considered in this study over a reasonably wide range of temperature, pH, p

Cross Sections Calculations of ( d, t) Nuclear Reactions up to 50 MeV

Science.gov (United States)

Tel, E.; Yiğit, M.; Tanır, G.

2013-04-01

In nuclear fusion reactions two light atomic nuclei fuse together to form a heavier nucleus. Fusion power is the power generated by nuclear fusion processes. In contrast with fission power, the fusion reaction processes does not produce radioactive nuclides. The fusion will not produce CO2 or SO2. So the fusion energy will not contribute to environmental problems such as particulate pollution and excessive CO2 in the atmosphere. Fusion powered electricity generation was initially believed to be readily achievable, as fission power had been. However, the extreme requirements for continuous reactions and plasma containment led to projections being extended by several decades. In 2010, more than 60 years after the first attempts, commercial power production is still believed to be unlikely before 2050. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. In the fusion reactor, tritium self-sufficiency must be maintained for a commercial power plant. Therefore, for self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. Working out the systematics of ( d, t) nuclear reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. Since the experimental data of charged particle induced reactions are scarce, self-consistent calculation and analyses using nuclear theoretical models are very important. In this study, ( d, t) cross sections for target nuclei 19F, 50Cr, 54Fe, 58Ni, 75As, 89Y, 90Zr, 107Ag, 127I, 197Au and 238U have been investigated up to 50 MeV deuteron energy. The excitation functions for ( d, t) reactions have been calculated by pre-equilibrium reaction mechanism. Calculation results have been also compared with the available measurements in

Analysis of 2H(rvec d,p)3H reaction by the four-body Faddeev-Yakubovsky equations

International Nuclear Information System (INIS)

Uzu, E.; Oryu, S.; Tanifuji, M.

1995-01-01

Very low energy 2 H(rvec d,p) 3 H reactions are investigated by using the four-body Fadeev-Yakubovsky integral equations. The adopted potential is the Ernst-Shakin-Thaler's separable expansion of the Paris potential or the PEST potential. The [3+1] and the [2+2] sub-amplitudes are given by the Hilbert-Schmidt rank-2, rank-3 and rank-4 separable expansion. The calculated total cross section, differential cross section, and tensor analyzing powers at 30keV-90keV are in very good agreement with the experimental data. copyright 1995 American Institute of Physics

Asymmetric H-D exchange reactions of fluorinated aromatic ketones

KAUST Repository

Zhao, Yujun

2012-01-01

Chiral bicyclic guanidine catalyzes the asymmetric H-D exchange reactions. Up to 30% ee was achieved. DFT calculations were employed to elucidate and explain the origin of the reaction\\'s stereoselectivity. © 2012 The Royal Society of Chemistry.

Separation of reaction mechanisms at low energy. Study of the reactions: 27Al(d,p) 28Al, 24Mg(d,p) 25Mg, and 24Mg(d, α) 22Na

International Nuclear Information System (INIS)

Mermaz, M.

1966-06-01

The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction 24 Mg(d, α) 22 Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of 22 Na. The angular distribution of the wide resonance at 15.9 MeV in 26 Al has been obtained. (author) [fr

An integral experiment on thorium oxide/depleted uranium cylinders with D-T neutrons for 232Th(n, 2n) reaction

International Nuclear Information System (INIS)

Feng, S.; Yang, Y.W.; Lu, X.X.; Liu, R.; Jiang, L.; Zhu, T.H.; Wang, M.; Qin, J.G.

2015-01-01

Highlights: • An integral experiment for 232 Th(n, 2n) reaction was carried out on the newly-established ThO 2 /depleted uranium cylinders. • 232 Th(n, 2n) reaction rate distribution was obtained in the assemblies with an uncertainty of about 7%. • Experiments were analyzed by MCNP code with ENDF/B-VI.8, ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries. • Experimental results could be used to re-evaluate the cross sections of 232 Th(n, 2n) reaction. - Abstract: In order to verify the evaluated cross sections of 232 Th(n, 2n) reaction for the conceptual design of the thorium based subcritical blanket in the fusion–fission hybrid reactor, an integral experiment on thorium oxide/depleted uranium cylinders was carried out with D-T neutrons using the activation technique. 232 Th(n, 2n) reaction rate distribution was obtained at the central axis direction in the assemblies with an uncertainty of about 7%. Experiments were analyzed by using MCNP code with ENDF/B-VI.8, ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries to validate the nuclear data libraries of 232 Th(n, 2n) reaction, the calculated results with JENDL-4.0 agree with the measurements the best with discrepancies within the experimental uncertainty. The average values of C/E for the three benchmark assemblies are 1.058, 1.044 and 0.980. Calculations with different evaluated libraries in the benchmark assemblies show a large discrepancy. The experimental results can be used to re-evaluate the cross sections of the 232 Th(n, 2n) reaction

Notable light-free catalytic activity for pollutant destruction over flower-like BiOI microspheres by a dual-reaction-center Fenton-like process.

Science.gov (United States)

Wang, Liang; Yan, Dengbiao; Lyu, Lai; Hu, Chun; Jiang, Ning; Zhang, Lili

2018-10-01

BiOI is widely used as photocatalysts for pollutant removal, water splitting, CO 2 reduction and organic transformation due to its excellent photoelectric properties. Here, we report for the first time that a light-free catalyst consisting of the flower-like BiOI microspheres (f-BiOI MSs) exposing (1 0 1) and (1 1 0) crystal planes prepared by a hydrothermal method in ethylene glycol environment can rapidly eliminate the refractory BPA within only ∼3 min through a Fenton-like process. The reaction activity is ∼190 times higher than that of the conventional Fenton catalyst Fe 2 O 3 . A series of characterizations and experiments reveal the formation of the dual reaction centers on f-BiOI MSs. The electron-rich O centers efficiently reduce H 2 O 2 to OH, while the electron-poor oxygen vacancies capture electrons from the adsorbed pollutants and divert them to the electron-rich area during the Fenton-like reactions. By these processes, pollutants are degraded and mineralized quickly in a wide pH range. Our findings address the problems of the classical Fenton reaction and are useful for the development of efficient Fenton-like catalysts through constructing dual reaction centers. Copyright © 2018 Elsevier Inc. All rights reserved.

Redox reactions of 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Barik, A; Priyadarsini, K I; Mohan, Hari

2004-08-01

Pulse radiolysis technique has been employed to study the reactions of oxidizing ({sup {center_dot}}OH, N{sub 3}{sup {center_dot}}) and reducing radicals (e{sup -}{sub aq}, CO{sub 2}{sup {center_dot}}{sup -}, acetone ketyl radical) with 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) at different pH. Hydroxyl radicals react mostly by addition reaction forming radical adducts ({lambda}{sub max}=420 nm) and the oxidation is only a minor process even in the alkaline region. The reaction with azide radicals produced phenoxyl radicals ({lambda}{sub max}=340 nm), which are formed on fast deprotonation of solute radical cation. Using PMZ{sup {center_dot}}{sup +}/PMZ and ABTS{sup {center_dot}}{sup -}/ABTS{sup 2-} as the reference couple, different methods are employed to determine the one-electron reduction potential of o-vanillin and the average value is estimated to be 1.076{+-}0.004 V vs. NHE at pH 6. The phenoxyl radicals of o-vanillin were able to oxidize ABTS{sup 2-} quantitatively. The e{sub aq}{sup -} is observed to react with o-vanillin with rate constant value of 2x10{sup 10} dm{sup 3} mol{sup -1} s{sup -1}. CO{sub 2}{sup {center_dot}}{sup -} and acetone ketyl radical are also observed to react with o-vanillin by electron transfer mechanism and showed the formation of transient absorption bands with {lambda}{sub max} at 350 and 390 nm at pH 4.5 and 9.7, respectively. The pK{sub a} of the one-electron reduced species was determined to be 8.1. The results indicate that the aldehydic group is the most preferred site for electron addition.

Signatures for isoscalar spin transitions excited in (d, d,) reactions

International Nuclear Information System (INIS)

Morlet, M.; Willis, A.; Van de Wiele, J.; Marty, N.; Guillot, J.; Langevin-Joliot, H.; Bimbot, L.; Rosier, L.; Djalali, C.; Duchazeaubeneix, J.C.

1990-01-01

Three different signatures for isoscalar spin transitions in nuclei have been tested in the 12 C(d, d , ) 12 C reaction at 400 MeV. These signatures have values of close to zero for the natural parity states, and values ranging from 0.22 to 0.50 for the ΔS=1 ΔT=0, 12.7 MeV state

Cross sections for (p,n) and (d,2n) reactions on /sup 79/Br and /sup 127/I: An evaluation of literature and model calculated results

Energy Technology Data Exchange (ETDEWEB)

Lanier, R.G.; Mustafa, M.G.; West, H.I. Jr.

1989-02-01

We have evaluated (p,n) and (d,2n) cross sections on /sup 79/Br and /sup 127/I, and made these cross sections available for test diagnostics. We believe that these interim cross sections are of reasonable accuracy and should be used for diagnostic interpretations until more precise measurements can be made. Our evaluation consisted of a literature search and an examination of the available experimental data. These data were supplemented by statistical model calculations using both the STAPRE and ALICE codes. We found reasonably good measured data (from threshold to the peak of the excitation function) for the (p,n) reaction on both /sup 79/Br and /sup 127/I. The literature data for the (d,2n) reaction on /sup 127/I are questionable and no data were found for the (d,2n) reaction on /sup 79/Br. We have, therefore, relied completely on calculations for the (d,2n) cross sections for both /sup 79/Br and /sup 127/I. 4 figs., 5 tabs.

Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

International Nuclear Information System (INIS)

Schwerer, O.; Lemmel, H.D.

1996-11-01

This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs

Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

International Nuclear Information System (INIS)

Pronyaev, V.G.; Schwerer, O.

1998-07-01

This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author)

Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

Energy Technology Data Exchange (ETDEWEB)

Schwerer, O; Lemmel, H D [eds.

1996-11-01

This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ``EXFOR`` system, and the further development of this system; the ``CINDA`` system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ``ENDF`` format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs.

The breakdown of vinyl ethers as a two-center synchronous reaction

Science.gov (United States)

Pokidova, T. S.; Shestakov, A. F.

2009-11-01

The experimental data on the molecular decomposition of vinyl ethers of various structures to alkanes and the corresponding aldehydes or ketones in the gas phase were analyzed using the method of intersecting parabolas. The enthalpies and kinetic parameters of decomposition were calculated for 17 reactions. The breakdown of ethers is a two-center concerted reaction characterized by a very high classical potential barrier to the thermally neutral reaction (180-190 kJ/mol). The kinetic parameters (activation energies and rate constants) of back reactions of the formation of vinyl ethers in the addition of aldehydes or ketones to alkanes were calculated using the method of intersecting parabolas. The factors that influenced the activation energy of the decomposition and formation of ethers were discussed. Quantum-chemical calculations of several vinyl ether decomposition reactions were performed. Ether formation reactions were compared with the formation of unsaturated alcohols as competitive reactions, which can occur in the interaction of carbonyl compounds with alkenes.

Kinetics of reaction between Mu and Ni"2"+ in superheated water

International Nuclear Information System (INIS)

Legate, G.; Alcorn, C.; Brodovitch, J.-C.; Ghandi, K.; Percival, P.W.

2011-01-01

Rates of spin exchange of muonium with Ni"2"+ in sub and supercritical D_2O were investigated using muon spin spectroscopy (μSR). The procedure for determining rate constants of muonium reactions is described. Then, results for the reaction of muonium with Ni"2"+ in D_2O are compared to previous data obtained for Ni"2"+ in H_2O. The rate constants are presented as functions of temperature, pressure, viscosity and density to explore possible contributions to the solvent isotope effects. (author)

Reactivity and reaction rate measurements in U--D2O lattices with coaxial fuel

International Nuclear Information System (INIS)

Pellarin, D.J.; Morris, B.M.

1976-12-01

Integral reaction rate parameters, intracell thermal neutron flux profiles, and material bucklings were measured for D 2 O-moderated uniform lattices in the exponential facility at the Savannah River Laboratory. Two different slightly enriched coaxial uranium fuel assemblies were examined over a wide range of triangular lattice pitches. Integral parameters are reported for inner and outer fuel separately providing data for a more detailed and rigorous comparison with computation than has been previously available. Results are compared with RAHAB calculations using ENDF/B-IV cross sections. Large discrepancies in agreement between calculation and experiment, outside of experimental errors and uncertainties in the input cross sections, probably result from the resonance capture models used by RAHAB

Electron color centers in SrF2-Na crystals

International Nuclear Information System (INIS)

Kachan, S.I.; Chornij, Z.P.

2006-01-01

A radiation-induced memory effect in SrF 2 -Na crystals is studied. It was shown that optical bleaching of M + A color centers at 80 K in SrF 2 -Na crystals causes the core of an M + A -center to transform into the V + a Me + V + a configuration, in which all three point defects are arranged diagonally in the cube cell. Reirradiation of an optically bleached crystal by X-rays generates F D centers in it. The F D →M + A transformation in SrF 2 -Na crystals occurs at T = 135 K, in contrast to the F A →M + A transformations, which take place at T > 200 K [ru

Forward-backward asymmetry in the reaction np → dπ0

International Nuclear Information System (INIS)

Hiebert, J.C.

1989-01-01

Two experiments are being designed to measure the forward-backward asymmetry in the center of mass differential cross sections for the np → dπ 0 reaction and thus provide additional tests of the charge symmetry breaking part of the NN interaction. One of these experiments is proposed at 477 MeV at TRIUMF and the other at selected energies between 600 and 800 MeV at LAMPF. The experimental challenges in measuring these cross section differences to the order of a few tenths of a percent are described. In addition, preliminary results at 800 MeV are presented from a Monte Carlo code written to simulate the LAMPF experiment. 7 refs., 3 figs

Theoretical investigation of the oxidation pathways of the Cl-initiated reaction of 2-methyl-3-buten-2-ol

Science.gov (United States)

Zhang, Weichao; Zhang, Dongju

2012-12-01

The mechanism and products of the reaction of 2-methyl-3-buten-2-ol (MBO232) with Cl atoms in the presence of O2 have been elucidated by performing high-level quantum chemistry calculations. The geometries of the reactants, intermediates, transition states, and products are optimized at the MP2(full)/6-311G(d, p) level, and their single-point energies are refined at the CCSD(T)/6-311 + G(d, p) level. The potential energy surface profiles have been constructed at the CCSD(T)/6-311 + G(d, p)//MP2(full)/6-311G(d, p) + 0.95 × ZPE level of theory, and the possible channels involved in the reaction are also discussed. The calculations indicate that the reaction predominantly proceeds via the addition of Cl atoms to the double bond rather than the direct abstraction of the H atoms in MBO232. The nascent adducts (CH3)2C(OH)CHCH2Cl (IM1) and (CH3)2C(OH)CHClCH2 (IM2) do not undergo subsequent isomerization and dissociation reactions, but rather react with O2. The theoretical results show that the major products are CH2ClCHO and CH3C(O)CH3 for the reaction of MBO232 + Cl in the presence of O2, which is in good agreement with the experimental finding.

Reaction of LiD with moisture by temperature programmed reaction (TPR)

International Nuclear Information System (INIS)

Dinh, L N; Balooch, M; Cecala, C M; Leckey, J H

2000-01-01

The temperature programmed reaction technique was performed on LiOH powders and LiD single crystals previously exposed to different moisture levels. Our results show that the LiOH decomposition process has an activation energy barrier of 30 to 33.1 kcal/mol. The LiOH structure is stable at 320 K for 100 years. However, LiOH structures formed on the surface of LiD during moisture exposure at low dosages may have multiple activation energy barriers, some of which may be much lower than 30 kcal/mol. We attribute the lowering of the activation energy barrier for the LiOH decomposition to the existence of dangling bonds, cracks, and other long range disorders in the LiOH structures formed at low levels of moisture exposure. These defective LiOH structures may decompose significantly over the next 100 years of storage even at room temperature. At high moisture exposure levels, LiOH.H 2 O formation is observed. The release of H 2 O molecules from LiOH.H 2 O structure has small activation energy barriers in the range of 13.8 kcal/mol to 16.0 kcal/mol. The loosely bonded H 2 O molecules in the LiOH.H 2 O structure can be easily pumped away at room temperature in a reasonable amount of time. Our experiments also suggest that handling LiD single crystals at an elevated temperature of 340 K or more reduces the growth of LiOH and LiOH.H 2 O significantly

F/Cl + C2H2 reactions: Are the addition and hydrogen abstraction direct processes?

International Nuclear Information System (INIS)

Li Jilai; Geng Caiyun; Huang Xuri; Zhan Jinhui; Sun Chiachung

2006-01-01

The reactions of atomic radical F and Cl with acetylene have been studied theoretically using ab initio quantum chemistry methods and transition state theory. The doublet potential energy surfaces were calculated at the CCSD(T)/aug-cc-pVDZ//CCSD/6-31G(d,p), CCSD(T)/aug-cc-pVDZ//UMP2/6-311++G(d,p) and compound method Gaussian-3 levels. Two reaction mechanisms including the addition-elimination and the hydrogen abstraction reaction mechanisms are considered. In the addition-elimination reactions, the halogen atoms approach C 2 H 2 , perpendicular to the C≡C triple bond, forming the pre-reactive complex C1 at the reaction entrance. C1 transforms to intermediate isomer I1 via transition state TSC1/1 with a negative/small barrier for C 2 H 2 F/C 2 H 2 Cl system, which can proceed by further eliminating H atom endothermally. While the hydrogen abstraction reactions also involve C1 for the fluorine atom abstraction of hydrogen, yet the hydrogen abstraction by chlorine atom first forms a collinear hydrogen-bonded complex C2. The other reaction pathways on the doublet PES are less competitive due to thermodynamical or kinetic factors. According to our results, the presence of pre-reactive complexes indicates that the simple hydrogen abstraction and addition in the halogen atoms reaction with unsaturated hydrocarbon should be more complex. Furthermore, based on the analysis of the kinetics of all channels through which the addition and abstraction reactions proceed, we expect that the actual feasibility of the reaction channels may depend on the reaction conditions in the experiment. The present study may be helpful for probing the mechanisms of the title reactions and understanding the halogen chemistry

Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

Energy Technology Data Exchange (ETDEWEB)

Pronyaev, V G; Schwerer, O [eds.

1998-07-01

This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ``EXFOR`` system, and the further development of this system; the ``CINDA`` system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ``ENDF`` format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author) Refs, figs, tabs

Theoretical description of spin-selective reactions of radical pairs diffusing in spherical 2D and 3D microreactors

International Nuclear Information System (INIS)

Ivanov, Konstantin L.; Lukzen, Nikita N.; Sadovsky, Vladimir M.

2015-01-01

In this work, we treat spin-selective recombination of a geminate radical pair (RP) in a spherical “microreactor,” i.e., of a RP confined in a micelle, vesicle, or liposome. We consider the microreactor model proposed earlier, in which one of the radicals is located at the center of the micelle and the other one undergoes three-dimensional diffusion inside the micelle. In addition, we suggest a two-dimensional model, in which one of the radicals is located at the “pole” of the sphere, while the other one diffuses on the spherical surface. For this model, we have obtained a general analytical expression for the RP recombination yield in terms of the free Green function of two-dimensional diffusion motion. In turn, this Green function is expressed via the Legendre functions and thus takes account of diffusion over a restricted spherical surface and its curvature. The obtained expression allows one to calculate the RP recombination efficiency at an arbitrary magnetic field strength. We performed a comparison of the two models taking the same geometric parameters (i.e., the microreactor radius and the closest approach distance of the radicals), chemical reactivity, magnetic interactions in the RP and diffusion coefficient. Significant difference between the predictions of the two models is found, which is thus originating solely from the dimensionality effect: for different dimensionality of space, the statistics of diffusional contacts of radicals becomes different altering the reaction yield. We have calculated the magnetic field dependence of the RP reaction yield and chemically induced dynamic nuclear polarization of the reaction products at different sizes of the microreactor, exchange interaction, and spin relaxation rates. Interestingly, due to the intricate interplay of diffusional contacts of reactants and spin dynamics, the dependence of the reaction yield on the microreactor radius is non-monotonous. Our results are of importance for (i) interpreting

Site Energies of Active and Inactive Pheophytins in the Reaction Center of Photosystem II from Chlamydomonas Reinhardtii

Energy Technology Data Exchange (ETDEWEB)

Acharya, K.; Neupane, B.; Zazubovich, V.; Sayre, R. T.; Picorel, R.; Seibert, M.; Jankowiak, R.

2012-03-29

It is widely accepted that the primary electron acceptor in various Photosystem II (PSII) reaction center (RC) preparations is pheophytin {alpha} (Pheo {alpha}) within the D1 protein (Pheo{sub D1}), while Pheo{sub D2} (within the D2 protein) is photochemically inactive. The Pheo site energies, however, have remained elusive, due to inherent spectral congestion. While most researchers over the past two decades placed the Q{sub y}-states of Pheo{sub D1} and Pheo{sub D2} bands near 678-684 and 668-672 nm, respectively, recent modeling [Raszewski et al. Biophys. J. 2005, 88, 986-998; Cox et al. J. Phys. Chem. B 2009, 113, 12364-12374] of the electronic structure of the PSII RC reversed the assignment of the active and inactive Pheos, suggesting that the mean site energy of Pheo{sub D1} is near 672 nm, whereas Pheo{sub D2} ({approx}677.5 nm) and Chl{sub D1} ({approx}680 nm) have the lowest energies (i.e., the Pheo{sub D2}-dominated exciton is the lowest excited state). In contrast, chemical pigment exchange experiments on isolated RCs suggested that both pheophytins have their Q{sub y} absorption maxima at 676-680 nm [Germano et al. Biochemistry 2001, 40, 11472-11482; Germano et al. Biophys. J. 2004, 86, 1664-1672]. To provide more insight into the site energies of both Pheo{sub D1} and Pheo{sub D2} (including the corresponding Q{sub x} transitions, which are often claimed to be degenerate at 543 nm) and to attest that the above two assignments are most likely incorrect, we studied a large number of isolated RC preparations from spinach and wild-type Chlamydomonas reinhardtii (at different levels of intactness) as well as the Chlamydomonas reinhardtii mutant (D2-L209H), in which the active branch Pheo{sub D1} is genetically replaced with chlorophyll {alpha} (Chl {alpha}). We show that the Q{sub x}-/Q{sub y}-region site energies of Pheo{sub D1} and Pheo{sub D2} are {approx}545/680 nm and {approx}541.5/670 nm, respectively, in good agreement with our previous assignment

Response-function measurement of an NE213 scintillator using the [sup 2]H(d, n)[sup 3]He reaction

Energy Technology Data Exchange (ETDEWEB)

Aksoy, A. (Energy Research Lab., King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)); Coban, A. (Energy Research Lab., King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)); Naqvi, A.A. (Energy Research Lab., King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)); Khiari, F.Z. (Energy Research Lab., King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)); Hanly, J.M. (Duke Univ., Nuclear Labs., Durham, NC (United States)); Howell, C.R. (Duke Univ., Nuclear Labs., Durham, NC (United States)); Tornow, W. (Duke Univ., Nuclear Labs., Durham, NC (United States)); Felsher, P.D. (Duke Univ., Nuclear Labs., Durham, NC (United States)); Al-Ohali, M.A. (Duke Univ., Nuclear Labs., Durham, NC (United States)); Walter, R.L. (Duke Univ., Nuclear Labs., Durham, NC (United States))

1994-01-01

The response function of a 12.5 cm diameter NE213 scintillator detector has been measured over neutron energies ranging from 4.9 to 16.6 MeV. Beams of monoenergetic neutrons were produced using the [sup 2]H(d, n)[sup 3]He reaction. The response function is about 12% lower than previously reported values for a similar detector obtained using a continuous spectrum of neutrons from a [sup 252]Cf fission source. However, the present response function agrees with portions of data sets obtained in published work that used monoenergetic neutron source reactions. (orig.)

Oxygen depth profiling using the 16O(d,α)14N nuclear reaction

International Nuclear Information System (INIS)

Khubeis, I.; Al-Rjob, R.

1997-01-01

The excitation function of the 16 O(d,α) 14 N nuclear reaction has been determined in the deuteron energy range of 0.88-2.28 MeV. Major resonances are observed at deuteron energies of 0.98, 1.31, 1.53, 1.60, 1.73 and 2.22 MeV. The present results show good agreement with those of Haase and Khubeis, however there is a shift of 60 keV in the first resonance compared with the measurements of Amsel. The use of a thin surface barrier detector (t=22 μm) and a bias voltage of +20 V coupled with a proper pile-up rejection circuit has allowed the determination of the oxygen depth profiling to a resolution of 16 nm for thick targets. This method is efficient in eliminating interferences from other nuclear reactions such as 16 O(d,p) 17 O and 12 C(d,p) 19 C, where emitted protons have severely obscured α-particles from the 16 O(d,α) 14 N reaction. A 1.08 MeV deuteron beam has been employed to increase the α-yield from the target. The target has been tilted at 70 to enhance depth resolution. This reaction is well suited for the determination of oxygen concentration in oxides of high temperature superconductors. (orig.)

Fluence of dielectric constant (D), (H/sup +/) and (SO/sub 4/sup -2/) on the rate of redox reaction between tris (2,2-bipyridine) iron (II) and ceric sulphate in aqueous sulphuric acid medium

International Nuclear Information System (INIS)

Khattak, R.; Naqvi, I.I.; Farrukh, M.A.

2007-01-01

Kinetic of the redox reaction between tris (2,2-bipyridine)iron(II) cation and ceric sulphate has been studied in aqueous sulphuric acid medium. Different methods were employed for the determination of order of reaction. The order of reaction is found to be first with respect to reductant however retarding effect of increasing initial concentration of oxidant is found. Influence of (H/sup +/), (SO/sub 4/sup 2-) and dielectric constant (D) on the rate of redox reaction has also been studied. Increase in (H/sup +/) and dielectric constant of the medium retard the rate while enhancement of the (SO/sub 4/sup 2-/) accelerates the rate first and then the reaction goes towards retardation. Effects of (H/sup +/) and (SO/sub 4/sup 2-/) were studied by using acetic acid-sodium acetate buffer for the first one and varying ionic concentrations of the salt sodium sulphate for the latter one, whereas dielectric constant was varied by using 0%, 10% and 20% ethanol-water mixtures. Results of effects of each one of the factors i.e., H/sup +/, SO/sub 4/sup 2-/ and dielectric constant (D) have been compared and on the basis of these factors, (Ce(SO/sub 4/ )/sub 3/)/sup 2-/ is suggested to be the active species of cerium(IV). However a rate law consistent with the observed kinetic data has also been derived supporting the proposed mechanism. (author)

Definitive difference among [DS-D2O], [DS-H2O] and [Bulk-D2O] cells in the deuterization and deuterium-reaction

International Nuclear Information System (INIS)

Arata, Yoshiaki; Zhang, Yue Chang

2000-01-01

We observed a new phenomena that the enormous amount of deuterium/hydrogen can be absorbed quickly as a 'solute-atom' into fine metal powders embedded inside a double-structure (DS) cathode in the electrolyses of D 2 O and H 2 O-electrolytes, respectively, but such highly deuterated powders can be produced only using DS-cathode immersed in D 2 O-electrolyte; [DS-D 2 O], and never generated in H 2 O-electrolyte even using the DS-cathode; [DS-H 2 O]. On the other hand, [Bulk-D 2 O] with bulk-cathode made by the bulk Pd metal never produces highly deuterated metal as mentioned above even though using D 2 O-electrolyte. In short, the deuterium-concentration generating in [Bulk-D 2 O] is found to be much lower than that in [DS-D 2 O]. As a result, because of reason mentioned above, in marked contrast to the case with the [DS-D 2 O], neither excess heat nor 4 He production are observed with both [DS-H 2 O] and [Bulk-D 2 O]. (author)

Filtering reaction dynamics using nearside-farside theory and local angular momentum theory: application to the angular scattering of the H + D2(v(i) = 0, j(i) = 0) --> HD(v(f) = 3, j(f) = 0) + D reaction in the energy and time domains.

Science.gov (United States)

Monks, P D D; Connor, J N L; Bouakline, F

2009-04-23

We investigate methods for filtering reaction mechanisms in the angular scattering of the state-to-state reaction, H + D(2)(v(i) = 0, j(i) = 0, m(i) = 0) --> HD(v(f) = 3, j(f) = 0, m(f) = 0) + D, where v(i), j(i), and m(i) and v(f), j(f), and m(f) are initial and final vibrational, rotational, and helicity quantum numbers, respectively. The input to our filtrations is a new set of accurate quantum scattering matrix elements for total energies in the range 1.52-2.50 eV (in steps of 0.01 eV) and for total angular momentum quantum numbers in the range, 0-40, in steps of unity. We filter reaction mechanisms in both the energy domain and the time domain. The time-domain calculations employ the plane wave packet formulation of time-dependent scattering. The theoretical tools used are nearside-farside (NF) analysis of partial wave series for scattering amplitudes, together with NF local angular momentum (LAM) theory. An energy-domain LAM analysis reveals the existence of an important dynamical feature in the N scattering, a "trench" which bisects the (energy, angle) plane. We use the location of this trench to approximately filter two reaction mechanisms. Transformation to the time domain demonstrates that the two reaction mechanisms correspond to direct and delayed (by about 25 fs) scattering. Further analysis, including filtration in the time domain, shows that the pronounced LAM trench arises from the interference of the energy-domain analogues of the time-direct and time-delayed scattering. Our theory and results provide the first successful demonstration of reaction mechanism filtering carried out directly in the (energy, angle) domain. The calculations and results in this paper extend and complement earlier research reported by Monks, Connor, and Althorpe (Monks, P. D. D.; Connor, J. N. L.; Althorpe, S. C. J. Phys. Chem. A 2006, 110, 741; J. Phys. Chem. A 2007, 111, 10302).

Organolanthanide reagents and the Mukaiyama reaction

International Nuclear Information System (INIS)

Gong, L.

1989-01-01

The bis(pentamethylcyclopentadienyl) lutetium halide complex [(C 5 Me 5 ) 2 LuCl/center dot/THF] was synthesized and characterized. The crystal structure of this complex shows that the Lu is at the center of a distorted tetrahedron consisting of the centroids of two cyclopentadienyl rings, the oxygen atom of a tetrahydrofuran molecule and a chlorine atom. 1 H NMR studies of toluene-d 8 solutions of (C 5 Me 5 LuCl(THF) + THF, (TMS 2 CP) 2 LuCl(THF) + THF, and (MeCp) 2 LuCl(THF) + THF at various temperatures showed exchange processes between co- ordinated THF and free THF with average values of ΔG/sup ne/ of 13.0 /+-/ 0.3 kcal/mol, 11.1 /+-/ 0.1 kcal/mol and 2 Cp) 2 YbCl dimer, silyl enol ethers (R 1 R 2 C = C(OR 3 )OSiMe 3 )) react with benzaldehyde smoothly in dichloromethane at room temperature, giving >99% of the aldol silyl ether (isolated yield: 90%) within 3 h. At /minus/78/degrees/C, the reaction gives kinetically controlled diastereoselectivity, which was not observed in the TiCl 4 -mediated aldol reaction. The use of organoytterbium enolates shows promise result with respect to increased stereoselectivity, and indicates the importance of the bulky ligands on the metal center. In addition, Yb(III) species can retard retroaldol reaction owing to its mild Lewis acidity. 118 refs., 14 figs., 30 tabs

Preparation and luminescence properties of Eu2+-doped CaSi2O2-dN2+2/3d phosphors

International Nuclear Information System (INIS)

Gu Yunxin; Zhang Qinghong; Wang Hongzhi; Li Yaogang

2009-01-01

Eu 2+ -doped CaSi 2 O 2-d N 2+2/3d phosphors for white LED lamps were prepared by solid-state reaction, and the effects of heat-treatment conditions and the overall composition of host lattice on the optical properties have been discussed. Eu 2+ -doped CaSi 2 O 2-d N 2+2/3d displayed a single broad emission band peak at 540 nm, which could be assigned to the allowed transition of Eu 2+ from the lowest crystal field component of 4f 6 5d to 4f 7 ground-state level. The excitation band of samples, extending from UV to blue, is extremely wide, so the phosphors are suitable for white LED lamps in combination with a UV or blue LED dies. The highest PL intensity is found for the sample sintered at 1400 0 C. Moreover, the emission intensity decreases when N partially replaces O. A red shift of emission wavelength did not occur with increasing of the N content.

Hydrothermal synthesis of 2D MoS 2 nanosheets for electrocatalytic hydrogen evolution reaction

KAUST Repository

Muralikrishna, S.

2015-10-20

Nanostructured molybdenum disulfide (MoS) is a very promising catalyst for producing molecular hydrogen by electrochemical methods. Herein, we have designed and synthesized highly electocatalytically active 2D MoS nanosheets (NS) from molybdenum trioxide (MoO) by a facile hydrothermal method and have compared their electrocatalytic activities for hydrogen evolution reaction (HER). The electrochemical characterization was performed using linear sweep voltammetry (LSV) in acidic medium. The MoS NS show a HER onset potential at about 80 mV vs. reversible hydrogen electrode (RHE) which is much lower than MoO (300 mV). The MoS NS and MoO show a current density of 25 mA cm and 0.3 mA cm, respectively at an overpotential of 280 mV vs. RHE. The MoS NS showed an 83 times higher current density when compared to MoO. The Tafel slopes of the MoS NS and MoO were about 90 mV per dec and 110 mV per dec respectively. This suggests that MoS NS are a better electrocatalyst when compared to MoO and follow the Volmer-Heyrovsky mechanism for HER.

Hydrothermal synthesis of 2D MoS 2 nanosheets for electrocatalytic hydrogen evolution reaction

KAUST Repository

Muralikrishna, S.; Manjunath, K.; Samrat, D.; Reddy, Viswanath; Ramakrishnappa, T.; Nagaraju, Doddahalli H.

2015-01-01

Nanostructured molybdenum disulfide (MoS) is a very promising catalyst for producing molecular hydrogen by electrochemical methods. Herein, we have designed and synthesized highly electocatalytically active 2D MoS nanosheets (NS) from molybdenum trioxide (MoO) by a facile hydrothermal method and have compared their electrocatalytic activities for hydrogen evolution reaction (HER). The electrochemical characterization was performed using linear sweep voltammetry (LSV) in acidic medium. The MoS NS show a HER onset potential at about 80 mV vs. reversible hydrogen electrode (RHE) which is much lower than MoO (300 mV). The MoS NS and MoO show a current density of 25 mA cm and 0.3 mA cm, respectively at an overpotential of 280 mV vs. RHE. The MoS NS showed an 83 times higher current density when compared to MoO. The Tafel slopes of the MoS NS and MoO were about 90 mV per dec and 110 mV per dec respectively. This suggests that MoS NS are a better electrocatalyst when compared to MoO and follow the Volmer-Heyrovsky mechanism for HER.

Laboratory Study of the OH + Permethylsiloxane (L2, L3, D3, and D4) Reaction Rate Coefficients Between 240 and 370 K

Science.gov (United States)

Burkholder, J. B.; Bernard, F.; Papadimitriou, V. C.

2016-12-01

The atmospheric chemistry of organosiloxanes has recently been implicated in the formation of new particles as well as regional and indoor air quality. Methylsiloxanes with Sitextiles, health care and household products and in industrial applications as solvents and lubricants. They are released into the atmosphere during manufacturing, use, and disposal and have been observed in the atmosphere in ppb levels in certain locations. However, the fundamental chemical properties of this class of compounds, particularly their reactivity with the OH radical, are presently not fully characterized. In this work, the temperature dependence of the rate coefficients for the OH radical reaction with the simplest linear (L2 and L3) and cyclic (D3 and D4) siloxanes were measured: OH + (CH3)3SiOSi(CH3)3 = Products L2OH + [(CH3)3SiO]2Si(CH3)2 = Products L3OH + [-Si(CH3)2O-]3 = Products D3OH + [-Si(CH3)2O-]4 = Products D4OH rate coefficients were measured under pseudo-first conditions in OH over the temperature range 240-370 K using a pulsed laser photolysis-laser induced fluorescence (PLP-LIF) technique and at 296 K using a relative rate method. The present results are compared with available literature data where possible and discrepancies are discussed. The results from this work will be discussed in terms of the atmospheric lifetimes of these methylsiloxanes and the reactivity trends for this class of compound.

Reaction of nickel with uranium mononitride; Reaction du nickel avec le nitrure d'uranium

Energy Technology Data Exchange (ETDEWEB)

Anselin, F; Calais, D; Lorenzelli, N; Passefort, J C [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1965-07-01

UN-Ni system has been investigated in solid phase by diffusion couples UN-Ni or by mixed powders pressed and sintered. Studies have been carried out by micrography, X-rays and microanalysis with a CASTAING microprobe. UN-Ni compatibility is quite good up to 600 C; beyond this temperature diffusion zones corresponding to UNi{sub 5} and U{sub 2}N{sub 3} appear in the couples either reaction : 3 U N + 5 Ni {yields} U{sub 2}N{sub 3} + UNi{sub 5}; UN + 5 Ni {yields} UNi{sub 5}+ 1/2 N{sub 2} takes place from 700 C according to nitrogen pressure involved. For temperatures between 800 and 1000 C nickel solubility in uranium nitride is 1500 {+-} 500 wt ppm. (authors) [French] Le systeme UN-Ni a ete etudie par diffusion en phase solide a partir de couples (UN-Ni) ou de melanges pulverulents presses et frittes. Les techniques utilisees sont la micrographie, les rayons X et l'analyse ponctuelle a la microsonde de CASTAING. La compatibilite UN-Ni est bonne jusqu'a 600 C; au-dela il apparait dans les couples de diffusion des zones correspondant a UNi{sub 5} et U{sub 2}N{sub 3}. L'une ou l'autre des deux reactions: 3UN + 5 Ni {yields} U{sub 2}N{sub 3} + UNi{sub 5}; UN + 5 Ni {yields} UNi{sub 5} + 1/2 N{sub 2} se produisant des 700 C suivant la pression d'azote exercee. La solubilite du nickel dans le nitrure d'uranium pour des temperatures comprises entre 800 et 1000 C est de 1500 {+-} 500 ppm en poids. (auteurs)

High-spin levels in 39K excited by the 41Ca(d,α) reaction

International Nuclear Information System (INIS)

Sugarbaker, E.; Boyd, R.N.; Cline, D.; Vold, P.B.; Lien, J.R.; Goode, P.R.

1979-01-01

The 41 Ca(d,α) 39 K reaction has been used to investigate the low-lying high-spin states in 39 K. Conflicting spin assignments for the 5.719 MeV level in 39 K of 9/2 - of 13/2 - have been suggested in earlier studies. A 1p-2h model reproduces both the 41 Ca(d,α) 39 K and 39 K(α,α') 39 K reaction data leading to the high-spin states if the 5.719 MeV level is assumed to have a J/sup π/ of 13/2 - . An alternate assignment of J/sup π/ = 9/2 - for this level is shown to produce very poor agreement with the model predictions

Structure Effects of 2D Materials on α-Nickel Hydroxide for Oxygen Evolution Reaction.

Science.gov (United States)

Luan, Chenglong; Liu, Guangli; Liu, Yujie; Yu, Lei; Wang, Yao; Xiao, Yun; Qiao, Hongyan; Dai, Xiaoping; Zhang, Xin

2018-04-24

To engineer low-cost, high-efficiency, and stable oxygen evolution reaction (OER) catalysts, structure effects should be primarily understood. Focusing on this, we systematically investigated the relationship between structures of materials and their OER performances by taking four 2D α-Ni(OH) 2 as model materials, including layer-stacked bud-like Ni(OH) 2 -NB, flower-like Ni(OH) 2 -NF, and petal-like Ni(OH) 2 -NP as well as the ultralarge sheet-like Ni(OH) 2 -NS. For the first three (layer-stacking) catalysts, with the decrease of stacked layers, their accessible surface areas, abilities to adsorb OH - , diffusion properties, and the intrinsic activities of active sites increase, which accounts for their steadily enhanced activity. As expected, Ni(OH) 2 -NP shows the lowest overpotential (260 mV at 10 mA cm -2 ) and Tafel slope (78.6 mV dec -1 ) with a robust stability over 10 h among the samples, which also outperforms the benchmark IrO 2 (360 mV and 115.8 mV dec -1 ) catalyst. Interestingly, Ni(OH) 2 -NS relative to Ni(OH) 2 -NP exhibits even faster substance diffusion due to the sheet-like structure, but shows inferior OER activity, which is mainly because the Ni(OH) 2 -NP with a smaller size possesses more active boundary sites (higher reactivity of active sites) than Ni(OH) 2 -NS, considering the adsorption properties and accessible surface areas of the two samples are quite similar. By comparing the different structures and their OER behaviors of four α-Ni(OH) 2 samples, our work may shed some light on the structure effect of 2D materials and accelerate the development of efficient OER catalysts.

Eight-dimensional quantum reaction rate calculations for the H+CH4 and H2+CH3 reactions on recent potential energy surfaces.

Science.gov (United States)

Zhou, Yong; Zhang, Dong H

2014-11-21

Eight-dimensional (8D) transition-state wave packet simulations have been performed on two latest potential energy surfaces (PES), the Zhou-Fu-Wang-Collins-Zhang (ZFWCZ) PES [Y. Zhou, B. Fu, C. Wang, M. A. Collins, and D. H. Zhang, J. Chem. Phys. 134, 064323 (2011)] and the Xu-Chen-Zhang (XCZ)-neural networks (NN) PES [X. Xu, J. Chen, and D. H. Zhang, Chin. J. Chem. Phys. 27, 373 (2014)]. Reaction rate constants for both the H+CH4 reaction and the H2+CH3 reaction are calculated. Simulations of the H+CH4 reaction based on the XCZ-NN PES show that the ZFWCZ PES predicts rate constants with reasonable high accuracy for low temperatures while leads to slightly lower results for high temperatures, in line with the distribution of interpolation error associated with the ZFWCZ PES. The 8D H+CH4 rate constants derived on the ZFWCZ PES compare well with full-dimensional 12D results based on the equivalent m-ZFWCZ PES, with a maximum relative difference of no more than 20%. Additionally, very good agreement is shown by comparing the 8D XCZ-NN rate constants with the 12D results obtained on the ZFWCZ-WM PES, after considering the difference in static barrier height between these two PESs. The reaction rate constants calculated for the H2+CH3 reaction are found to be in good consistency with experimental observations.

Development of a multiplex polymerase chain reaction-sequence-specific primer method for NKG2D and NKG2F single-nucleotide polymorphism typing using isothermal multiple displacement amplification products.

Science.gov (United States)

Kaewmanee, M; Phoksawat, W; Romphruk, A; Romphruk, A V; Jumnainsong, A; Leelayuwat, C

2013-06-01

Natural killer group 2 member D (NKG2D) on immune effector cells recognizes multiple stress-inducible ligands. NKG2D single-nucleotide polymorphism (SNP) haplotypes were related to the levels of cytotoxic activity of peripheral blood mononuclear cells. Indeed, these polymorphisms were also located in NKG2F. Isothermal multiple displacement amplification (IMDA) is used for whole genome amplification (WGA) that can amplify very small genomic DNA templates into microgram with whole genome coverage. This is particularly useful in the cases of limited amount of valuable DNA samples requiring multi-locus genotyping. In this study, we evaluated the quality and applicability of IMDA to genetic studies in terms of sensitivity, efficiency of IMDA re-amplification and stability of IMDA products. The smallest amount of DNA to be effectively amplified by IMDA was 200 pg yielding final DNA of approximately 16 µg within 1.5 h. IMDA could be re-amplified only once (second round of amplification), and could be kept for 5 months at 4°C and more than a year at -20°C without loosing genome coverage. The amplified products were used successfully to setup a multiplex polymerase chain reaction-sequence-specific primer for SNP typing of the NKG2D/F genes. The NKG2D/F multiplex polymerase chain reaction (PCR) contained six PCR mixtures for detecting 10 selected SNPs, including 8 NKG2D/F SNP haplotypes and 2 additional NKG2D coding SNPs. This typing procedure will be applicable in both clinical and research laboratories. Thus, our data provide useful information and limitations for utilization of genome-wide amplification using IMDA and its application for multiplex NKG2D/F typing. © 2013 John Wiley & Sons Ltd.

The D(+) + H2 reaction: differential and integral cross sections at low energy and rate constants at low temperature.

Science.gov (United States)

González-Lezana, Tomás; Scribano, Yohann; Honvault, Pascal

2014-08-21

The D(+) + H2 reaction is investigated by means of a time independent quantum mechanical (TIQM) and statistical quantum mechanical (SQM) methods. Differential cross sections and product rotational distributions obtained with these two theoretical approaches for collision energies between 1 meV and 0.1 eV are compared to analyze the dynamics of the process. The agreement observed between the TIQM differential cross sections and the SQM predictions as the energy increases revealed the role played by the complex-forming mechanism. The importance of a good description of the asymptotic regions is also investigated by calculating rate constants for the title reaction at low temperature.

Reaction of N-(Per-O-acetyl-β-D-glucopyranosyl-Nʼ-(4ʼ,6ʼ-diarylpyrimidine-2ʼ-ylthioureas with Ethyl Bromoacetate

Directory of Open Access Journals (Sweden)

Nguyen Dinh Thanh

2011-01-01

Full Text Available Some new 2-iminothiazolidin-4-ones having pyrimidine ring have been synthesized by reaction of substituted N-(per-O-acetyl-β-D-glucopyranosyl-Nʼ-(4ʼ,6ʼ-diarylpyrimidine-2ʼ-ylthioureas with ethyl bromoacetate. The structure of isomeric products has been confirmed by spectroscopic methods, such as IR, 1H and 13C NMR.

Remeasurement of p/suby/ for the 2H(d, n)3He reaction and its bearing on the reported f-wave admixture of the lowest 2- state in 4He

International Nuclear Information System (INIS)

Tornow, W.; Skubic, S.E.; Byrd, R.C.; Lisowski, P.W.; Walter, R.L.

1976-01-01

The polarization of neutrons from the reaction 2 H(d, n) 3 He has been measured for a deuteron energy E/subd/ = 2.44 MeV at emission angles of 45degree and 55degree (lab). The polarization values are discussed in relation both to previously reported discrepant data and to measured differences between p/suby/ and A/suby/ in the reaction 3 H(p, n) 3 He

Asymmetric H-D exchange reactions of fluorinated aromatic ketones

KAUST Repository

Zhao, Yujun; Lim, XiaoZhi; Pan, Yuanhang; Zong, Lili; Feng, Wei; Tan, Choonhong; Huang, Kuo-Wei

2012-01-01

Chiral bicyclic guanidine catalyzes the asymmetric H-D exchange reactions. Up to 30% ee was achieved. DFT calculations were employed to elucidate and explain the origin of the reaction's stereoselectivity. © 2012 The Royal Society of Chemistry.

The reaction 32S(d,alpha)30P

International Nuclear Information System (INIS)

Lawrie, J.J.

1979-03-01

Cross sections for the reaction 32 S(d,alpha) 30 P were measured at an average deuteron energy of about 6 MeV over deuteron energy ranges of about 200 - 400 KeV with steps of 15 KeV and at laboratory angles of 90 degrees, 112 degrees, 125 degrees, 133 degrees, 137 degrees, 141 degrees, 148 degrees, 155 degrees and 175,5 degrees. The range of excitation pertaining to the study, extended to the 23rd excited state at 4,73 MeV in 30 P. The observed cross section fluctuations in the excitation functions are indicative of the statistical nature of the reaction. A coherence width of 43 plus minus 4 keV was obtained for the compound nucleus 34 Cl at 17,2 MeV excitation from fluctuation analyses for states up to the 7th excited level at 2,84 MeV in 30 P. By contrast the coherence width for the isospin forbidden transition to the T = 1 excited state at 2,94 MeV in 30 P was found to be 34 plus minus 6 keV. This difference can be accounted for in terms of isospin mixing in the compound nucleus. Spins of excited states in 30 P were determined by comparing experimental cross sections with Hauser-Feshbach predictions. The most probable spin values obtained from this study are: 1 + for the 10th (3,73 MeV),2 + for the 11th (3,83 MeV),3 + for the 12th (3,93 MeV),0 + for the 16th (4,235 MeV) and 1 + for the 23rd excited state at 4,73 MeV in 30 P. From the assumption that the spin of the 17th excited state (4,30 MeV) is 2 - , spin possibilities of 2 + , 3 - and 4 + could be deduced for the 18th excited state (4,34 MeV). An inhibition factor of 0,41 plus minus 0,06 for the isospin forbidden reaction 32 S(d,alpha) 30 P has been obtained and corresponds to a value of = 18 keV for the compound nucleus 34 Cl at 17,2 MeV excitation

Differential cross-sections of a double spin-flip In d + d reactions and supermultiplet potential model of the interaction of clusters

CERN Document Server

Lebedev, V M; Struzhko, B G

2002-01-01

The experimental two-dimensional proton-proton coincidence spectra of the four-particle reaction d + d -> p + p + n + n are simulated with regard to dominant quasi-binary processes, viz. a quasi-free scattering of protons and final-state interaction of nucleons. Differential cross-sections d sigma (nu,E)/d OMEGA of a deuteron charge exchange sup 2 H(d, sup 2 n) sup 2 p reaction (0,57 +- 0.03 mb/sr at THETA sub c sub m 62,5 degree, 1,01 +- 0,05 mb /sr at THETA sub c sub m = 79,6 degree, E sub c sub m = 11,6 MeV) and spin-isospin flip sup 2 H(d,d sup *)d sup * one (1,1 +- 0,3 mb /sr at THETA sub c sub m = 90 degree E sub c sub m 23,4 MeV) are defined. They are compared to the cross-sections calculated in the approach of generalized (supermultiplet) potential model where the problem of the interaction of clusters A and B can be reduced to a set of one-channel scattering problems with potentials V sup [ f], where [f] are the allowed Young schemes for the system A + B. This is important for channels with minimum t...

Analysis of 2H(d vector, p)3H reaction at 30-90 keV by four-body Faddeev-Yakubovsky equation

International Nuclear Information System (INIS)

Uzu, Eizo; Oryu, Shinsho; Tanifuji, Makoto.

1993-01-01

Low-energy 2 H(d vector, p) 3 H reactions are investigated by the four-body Faddeev-Yakubovsky equations. Cross sections and tensor analyzing powers are calculated at 30-90 keV energies. The PEST-1 potentials are used for nucleon-nucleon interactions. The [2+2] and [3+1] subamplitudes are treated by the Hilbert-Schmidt expansions. Numerical results give qualitative explanation of experimental data. (author)

High-temperature shock tube and modeling studies on the reactions of methanol with D-atoms and CH3-radicals.

Science.gov (United States)

Peukert, S L; Michael, J V

2013-10-10

The shock tube technique has been used to study the hydrogen abstraction reactions D + CH3OH → CH2O + H + HD (A) and CH3 + CH3OH → CH2O + H + CH4 (B). For reaction A, the experiments span a T-range of 1016 K ≤ T ≤ 1325 K, at pressures 0.25 bar ≤ P ≤ 0.46 bar. The experiments on reaction B, CH3 + CH3OH, cover a T-range of 1138 K ≤ T ≤ 1270 K, at pressures around 0.40 bar. Reflected shock tube experiments, monitoring the depletion of D-atoms by applying D-atom atomic resonance absorption spectrometry (ARAS), were performed on reaction A using gas mixtures of C2D5I and CH3OH in Kr bath gas. C2D5I was used as precursor for D-atoms. For reaction B, reflected shock tube experiments monitoring H-atom formation with H-ARAS, were carried out using gas mixtures of diacetyl ((CH3CO)2) and CH3OH in Kr bath gas. (CH3CO)2 was used as the source of CH3-radicals. Detailed reaction models were assembled to fit the D-atom and H-atom time profiles in order to obtain experimental rate constants for reactions A and B. Total rate constants from the present experiments on D + CH3OH and CH3 + CH3OH can be represented by the Arrhenius equations kA(T) = 1.51 × 10(-10) exp(-3843 K/T) cm(3) molecules(-1) s(-1) (1016 K ≤ T ≤ 1325 K) and kB(T) = 9.62 × 10(-12) exp(-7477 K/T) cm(3) molecules(-1) s(-1) (1138 K ≤ T ≤ 1270 K). The experimentally obtained rate constants were compared with available rate data from the literature. The results from quantum chemical studies on reaction A were found to be in good agreement with the present results. The present work represents the first direct experimental study on these bimolecular reactions at combustion temperatures and is important to the high-temperature oxidation of CH3OH.

Kinetics of reaction between Mu and Ni{sup 2+} in superheated water

Energy Technology Data Exchange (ETDEWEB)

Legate, G.; Alcorn, C. [Mount Allison Univ., Sackville, NB (Canada); Brodovitch, J.-C. [Simon Fraser Univ., Burnaby, BC (Canada); Ghandi, K. [Mount Allison Univ., Sackville, NB (Canada); Percival, P.W. [Simon Fraser Univ., Burnaby, BC (Canada); TRIUMF, Vancouver, BC (Canada)

2011-07-01

Rates of spin exchange of muonium with Ni{sup 2+} in sub and supercritical D{sub 2}O were investigated using muon spin spectroscopy (μSR). The procedure for determining rate constants of muonium reactions is described. Then, results for the reaction of muonium with Ni{sup 2+} in D{sub 2}O are compared to previous data obtained for Ni{sup 2+} in H{sub 2}O. The rate constants are presented as functions of temperature, pressure, viscosity and density to explore possible contributions to the solvent isotope effects. (author)

KONSTRUKSI MUTAN PROTEIN FOSFATASE ptc2D Saccharomyces cerevisiae DENGAN METODE PENGGANTIAN GEN TARGET DENGAN POLYMERASE CHAIN REACTION (PCR

Directory of Open Access Journals (Sweden)

Hermansyah

2011-05-01

Full Text Available Yeast Saccharomyces cerevisiae is an excellent model to studi genes function of eukarotic cells such as study of gene encoding protein phosphatase PTC2. Novel phenotypic caused by mutated gene is an important step to study function of gene. In this study constructed mutant of PTC2 gene encoding protein phosphatase. Method that used in this construction was replacement of target gene (PTC2 with auxotroph marker Candida albicans HIS3 by Polymer Chain Reaction (PCR or called by PCR-mediated disruption. Mutant colonies which grew in selective medium SC without histidine were confirmed by PCR amplification. By using 1% Agarose gel electrophoresis the result showed that size of ptc2D::CgHIS3 transformant was 3.52 kb while wild type strain was 2.9 kb, indicated that ptc2D::CgHIS3 has integrated on chromosome V replacing PTC2 wild type.

N33*++ isobar production and isospin 2 ππ interaction studied in the reaction π- p → p π+π-π- at 2.75 GeV/c

International Nuclear Information System (INIS)

Alitti, J.

1967-01-01

A study of the reaction π - p → p π + π - π - at 2.75 GeV/c was carried out in an 81 cm liquid hydrogen bubble chamber at the CERN proton synchrotron. One observes that the abundant N 33 *++ (1236 MeV) isobar production occurs predominantly backwards in the center of mass of the reaction. This feature suggests a peripheral production mechanism with π exchange. The validity of this hypothesis, which allows the study of the π - π - interaction within the frame of the Chew and Low model, is verified. Among other results one finds for the isospin-2 state the values of the elastic ππ cross section and of the S and D wave phase shifts. (author) [fr

Structure and Reaction Mechanism of Pyrrolysine Synthase (PylD)

KAUST Repository

Quitterer, Felix; Beck, Philipp; Bacher, Adelbert; Groll, Michael

2013-01-01

The final step in the biosynthesis of the 22nd genetically encoded amino acid, pyrrolysine, is catalyzed by PylD, a structurally and mechanistically unique dehydrogenase. This catalyzed reaction includes an induced-fit mechanism achieved by major structural rearrangements of the N-terminal helix upon substrate binding. Different steps of the reaction trajectory are visualized by complex structures of PylD with substrate and product. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure and Reaction Mechanism of Pyrrolysine Synthase (PylD)

KAUST Repository

Quitterer, Felix

2013-05-29

The final step in the biosynthesis of the 22nd genetically encoded amino acid, pyrrolysine, is catalyzed by PylD, a structurally and mechanistically unique dehydrogenase. This catalyzed reaction includes an induced-fit mechanism achieved by major structural rearrangements of the N-terminal helix upon substrate binding. Different steps of the reaction trajectory are visualized by complex structures of PylD with substrate and product. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

User-centered 3D geovisualisation

DEFF Research Database (Denmark)

Nielsen, Anette Hougaard

2004-01-01

. In a broader perspective, the overall aim is to develop a language in 3D Geovisualisation gained through usability projects and the development of a theoretical background. A conceptual level of user-centered 3D Geovisualisation is introduced by applying a categorisation originating from Virtual Reality...... and shadowing effects or with weather phenomena serving a level of realism and providing depth cues. The rendered objects and scenes are graphically accessible through the interface where immersive or non-immersive monitors in different sizes and shapes are relevant. Through the user interface, users can...

Tuning cofactor redox potentials: the 2-methoxy dihedral angle generates a redox potential difference of >160 mV between the primary (Q(A)) and secondary (Q(B)) quinones of the bacterial photosynthetic reaction center.

Science.gov (United States)

Taguchi, Alexander T; Mattis, Aidas J; O'Malley, Patrick J; Dikanov, Sergei A; Wraight, Colin A

2013-10-15

Only quinones with a 2-methoxy group can act simultaneously as the primary (QA) and secondary (QB) electron acceptors in photosynthetic reaction centers from Rhodobacter sphaeroides. (13)C hyperfine sublevel correlation measurements of the 2-methoxy in the semiquinone states, SQA and SQB, were compared with quantum mechanics calculations of the (13)C couplings as a function of the dihedral angle. X-ray structures support dihedral angle assignments corresponding to a redox potential gap (ΔEm) between QA and QB of ~180 mV. This is consistent with the failure of a ubiquinone analogue lacking the 2-methoxy to function as QB in mutant reaction centers with a ΔEm of ≈160-195 mV.

11. IAEA consultants' meeting of the nuclear reaction data centers. Obninsk, 7-11 October 1991

International Nuclear Information System (INIS)

Lemmel, H.D.

1992-03-01

This report summarizes the 1991 co-ordination meeting in Obninsk, Russia, of the national and regional nuclear reaction data centers, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation; the exchanged and documentation of evaluated data libraries in ENDF format, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials

[Polyketone Reaction in Biosynthetic Pathways of 2, 3, 5, 4'-Tetrahydroxy Stilhene-2-O-β-D-glucoside in Polygonum multiflorum by Biocatalysis].

Science.gov (United States)

Lei, Lei; Xia, Wan-xia; Shao, Li; Zhao, Shu-jin

2015-10-01

2, 3, 5, 4'-Tetrahydroxy stilbene-2-O-β-D-glucoside (THSG), the active ingredient of Polygonum multiflorum, its polyketone reaction in the biosynthesis pathways was studied by biocatalysis method. The substrates 4-coumaroyl-CoA and malonyl-CoA were catalyzed in vitro by the crude enzyme extracted from Polygonum multiflorum callus, then the products were verified by HPLC and LC-MS methods. And the crude enzyme was analyzed by ammonium sulfate precipitation method and SDS-PAGE. HPLC chromatogram showed the same retention time of both the product and resveratrol standards; LC-MS spectra showed that the m/z of product was 227, which was consistent with resveratrol standards under the mode of negative ion; Ammonium sulfate (AS) precipitation method showed AS of 40% - 70% had catalytic activity,and 50% - 60% was the optimum; SDS-PAGE showed protein bands were obviously different among different AS concentration between 20% - 80%, the protein band of 42 kDa was found in AS of 50% - 60%, which had the same molecular weight with stilbene synthase. The product of polyketone reaction in the biosynthesis of THSG is resveratrol rather than THSG, so it is speculated that THSG is the conversion product of resveratrol instead of the direct product of the polyketone reaction.

Molecular electronics of a single photosystem I reaction center: Studies with scanning tunneling microscopy and spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lee, I.; Lee, J.W.; Warmack, R.J.; Allison, D.P.; Greenbaum, E. [Oak Ridge National Lab., TN (United States)

1995-03-14

Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. 42 refs., 7 figs.

Kinematical coincidence method in transfer reactions

Energy Technology Data Exchange (ETDEWEB)

Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

2013-07-01

A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

12C(d,p) 13C reaction at Esub(d) = 30 MeV to the positive-parity states in 13C

International Nuclear Information System (INIS)

Ohnuma, H.; Hoshino, N.; Mikoshiba, O.

1985-07-01

The 12 C(d, p) 13 C reaction has been studied at Esub(d) = 30 MeV. All the known positive-parity states of 13 C below 10 MeV in excitation energy, including the 7/2 + and 9/2 + states, are observed in this reaction. The angular distributions for these positive-parity bound and unbound states are analyzed in CCBA frame work. The 13 C wave functions, which reproduce the resonant and non-resonant scattering of neutrons from 12 C, also give good accounts of the experimentally observed angular distributions and energy spectra of outgoing protons in the 12 C(d, p) 13 C reaction. In most cases the cross section magnitude and the angular distribution shape are primarily determined by the 0 + x j component, even if it is only a small fraction of the total wave function. An exception is the 7/2 + state, where the main contribution comes from the 2 + x dsub(5/2) component. The inclusion of the 4 + state in 12 C and the gsub(9/2) and gsub(7/2) neutron components in the n + 12 C system has very small effects on the low-spin states, but is indispensable for a good fit to the 7/2 + and 9/2 + angular distributions. The transitions to the negative-parity states, 1/2 1 - , 3/2 1 - , 5/2 - , 7/2 - and 1/2 3 - , are also observed experimentally, and analyzed by DWBA. (author)

Heavy-ion induced multinucleon transfer reactions in the 2s--1d shell

International Nuclear Information System (INIS)

Olmer, C.

1975-01-01

In order to investigate whether new nuclear structure information can be obtained from studying the direct transfer of more than two nucleons using heavy-ion projectiles, we have investigated the 28 Si( 16 O, 12 C) 32 S and 12 C( 14 N,d) 24 Mg reactions as candidates for the direct transfer of four- and twelve-nucleons, respectively. The counter telescope-position sensitive detector kinematic coincidence method--both angular distributions (22 0 less than theta/sub L/ less than 95 0 , E/sub L/ = 55.54 MeV) and excitation functions (theta/sub L/ = 26 0 , 50 less than E/sub L/ less than 63 MeV) were obtained for strongly excited states below 10 MeV in excitation in the first reaction. For the 12 C + 14 N interaction, a measurement of the angular distributions (25 0 less than theta/sub L/ less than 140 0 , E/sub L/ = 20,25 MeV) for proton, deuteron and alpha-particle emission to many low-lying states sufficed for the present purposes. Comparison of Hauser-Feshbach statistical model calculations with these data indicated that the light-particle production from the 12 C + 14 N interaction as investigated here is predominantly compound nuclear in nature. The selectively strong population of a few states in 32 S by the 28 Si-( 16 O, 12 C) 32 S reaction is primarily direct. The structure of these states was deduced from available light-ion-induced transfer reaction studies and shell model calculations; the importance of shell model configurations is indicated, and an alpha-particle transfer model can not account for the observed selectivity. Calculations of the 28 Si( 16 O, 12 C) 32 S reaction with a microscopic multinucleon transfer code indicate selectivities consistent with the present results. Moreover, the calculations suggest the presence of other, unexpected selectivities, all of which may be understood on a physical basis, and some of which appear as an extension of a similar effect seen in two-nucleon transfer reactions

DFT studies on the mechanism of the reaction of C2H5S with NO2

Science.gov (United States)

Tang, Yi-Zhen; Sun, Hao; Pan, Ya-Ru; Pan, Xiu-Mei; Wang, Rong-Shun

The mechanisms for the reaction of C2H5S with NO2 are investigated at the QCISD(T)/6-311++G(d, p)//B3LYP/6-311++G(d, p) level on both single and triple potential energy surfaces. The geometries, vibrational frequencies and zero-point energy (ZPE) corrections of all stationary points involved in the title reaction are calculated at the B3LYP/6-311++G(d, p) level. The results show that the reaction is more predominant on the single potential energy surface, while it is negligible on the triple potential energy surface. Without barrier height in the whole process, the major channel is R ? C2H5SONO (IM1 and IM2) ? P1 (C2H5SO+NO). With much heat released in the formation of C2H5SNO2 (IM3) and the transition state involved in the subsequent step more stable than reactants, P4 (CH3CHS + t-HONO) is subdominant product energetically.

Communication: Rovibrationally selected absolute total cross sections for the reaction H{sub 2}O{sup +}(X{sup 2}B{sub 1}; v{sub 1}{sup +}v{sub 2}{sup +}v{sub 3}{sup +}= 000; N{sup +}{sub Ka+Kc+)}+ D{sub 2}: Observation of the rotational enhancement effect

Energy Technology Data Exchange (ETDEWEB)

Xu Yuntao; Xiong Bo; Chang, Yih Chung; Ng, C. Y. [Department of Chemistry, University of California, Davis, California 95616 (United States)

2012-12-28

By employing the newly established vacuum ultraviolet laser pulsed field ionization-photoion (PFI-PI) double quadrupole-double octopole ion guide apparatus, we have measured the rovibrationally selected absolute total cross sections of the ion-molecule reaction H{sub 2}O{sup +}(X{sup 2}B{sub 1}; v{sub 1}{sup +}v{sub 2}{sup +}v{sub 3}{sup +}= 000; N{sup +}{sub Ka+Kc+)}+ D{sub 2}{yields} H{sub 2}DO{sup +}+ D in the center-of-mass collision energy (E{sub cm}) range of 0.05-10.00 eV. The pulsing scheme used for the generation of PFI-PIs has made possible the preparation of reactant H{sub 2}O{sup +}(X{sup 2}B{sub 1}; v{sub 1}{sup +}v{sub 2}{sup +}v{sub 3}{sup +}= 000) ions in single N{sup +}{sub Ka+Kc+} rotational levels with high kinetic energy resolutions. The absolute total cross sections observed in different N{sup +}{sub Ka+Kc+} levels with rotational energies in the range of 0-200 cm{sup -1} were found to exhibit a significant rotational enhancement on the reactivity for the titled reaction. In contrast, the measured cross sections reveal a decreasing trend with increasing E{sub cm}, indicating that the rotational enhancement observed is not a total energy effect, but a dynamical effect. Furthermore, the rotational enhancement is found to be more pronounced as E{sub cm} is decreased. This experiment provided evidence that the coupling of the core rotational angular momentum with the orbital angular momentum could play a role in chemical reactivity, particularly at low E{sub cm}.

Verification experiment of EPR paradox by (d, 2He) reaction

International Nuclear Information System (INIS)

Sakai, Hideyuki

2003-01-01

FBR paradox which was brought forward by Einstein, Podolsky and Rosen is expressed by Bell's inequality of spin correlation theoretically. In principle it is possible to verify the inequality by measuring spin correlation between two particles having spin 1/2 from a decay of 1 S 0 experimentally. Most of the past experiments to verify the inequality, however, have been performed by using photons. On the other hand, only one experiment by using hadron system was carried out by Lamehi and Mitting, where the [ 1 S 0 ] state was produced by proton-proton scattering at first, and then the spin orientations after the scattering were measured. Unfortunately, there exit some sources of ambiguity to reach definite conclusion from their result because the experiment was done at rather high energy of 13.5 MeV. In the experiment planned by the present author it is designed to overcome the experimental difficulties, which Lamehi and Mitting encountered, by (1) generating high purity singlet [ 1 S 0 ] state of two protons by (d, 2 He) type nuclear reaction at intermediate energy range, and by (2) developing high performance spin-correlation polarimeter which can analyze spins of two protons simultaneously to minimize the systematic errors. The excitation energy of 2 He corresponding to the proton-proton relative energy can be experimentally controlled. An idea singlet is realized by choosing the state with sufficiently small relative energy. It is planned to measure the spin correlation function by using SMART (Swinger and Magnetic Analyzer with Rotator and Twister) at RIKEN Accelerator Research Facility. Einstein POLarimeter (EPOL) to be installed on the second focal plane of SMART is under development, with which high precision measurements of spin orientations of two high energy protons simultaneously coming into limited space from 2 He decay are made selecting the subject events from very many background events. Monte Carlo simulation predicts the possibility to verify the

Novel support effects on the mechanism of propene-deuterium: Addition and exchange reactions over dispersed ZrO2

International Nuclear Information System (INIS)

Naito, Shuichi; Tanimoto, Mitsutoshi

1995-01-01

The effect on the rate and mechanisms of propene-deuterium reactions of dispersing ZrO 2 on various supports such as silica, alumina, and titanium dioxide has been studied by microwave spectroscopic analysis of monodeuteropropene as well as by kinetic investigation. By dispersal of ZrO 2 on these supports, the rate of the C 3 H 6 -D 2 reactions is increased considerbly compared to that over unsupported ZrO 2 , with the decrease of activation energy. Hydrogen exchange in propene proceeds simultaneously with addition via the associative mechanism through n-propyl and s-propyl intermediates. Through XPS analysis of ZrO 2 /SiO 2 , it was found that a monolayer of ZrO 2 is formed over the silica support. The monolayer catalyst exhibits catalytic behavior quite different from that of unsupported ZrO 2 . On the other hand, alumina surfaces modified by ZrO 2 layers may be the main active sites in the case of ZrO 2 /Al 2 O 3 . The marked enhancement of the reaction rate in the lower loading region of ZrO 2 /TiO 2 may be explained by the strong interaction of atomically dispersed zirconium ions with active centers on TiO 2 . 28 refs., 10 figs., 1 tab

Quantum wave packet study of D+OF reaction

International Nuclear Information System (INIS)

Kurban, M.; Karabulut, E.; Tutuk, R.; Goektas, F.

2010-01-01

The quantum dynamics of the D+OF reaction on the adiabatic potential energy surface of the ground 1 3 A ' state has been studied by using a time-dependent quantum real wave packet method. The state-to-state and state-to-all reaction probabilities for total angular momentum J = 0 have been calculated. The probabilities for J > 0 have been calculated by J-shifting the J = 0 results by means of capture model. Then, the integral cross sections and initial state selected rate constants have been calculated. The initial state-selected reaction probabilities and reaction cross section show threshold but not manifest any resonances and the initial state selected rate constants are sensitive to the temperature.

Probing α-particle wave functions using (rvec d,α) reactions

International Nuclear Information System (INIS)

Crosson, E.R.; Lemieux, S.K.; Ludwig, E.J.; Thompson, W.J.; Bisenberger, M.; Hertenberger, R.; Hofer, D.; Kader, H.; Schiemenz, P.; Graw, G.; Eiro, A.M.; Santos, F.D.

1993-01-01

Wave functions of the α particle corresponding to different S- and D-state deuteron-deuteron overlaps, left-angle dd|α right-angle, were investigated using exact finite-range distorted-wave Born-approximation (DWBA) analyses of (rvec d,α) reactions. Cross sections, vector, and tensor-analyzing powers were measured for (rvec d,α) reactions populating the lowest J π =7 + state in 56 Co at bombarding energies E d of 16 and 22 MeV, the lowest 7 + state in 48 Sc at E d =16 MeV, and the lowest 7 + state in 46 Sc at E d =22 MeV. We find that DWBA analyses of tensor-analyzing powers produce satisfactory agreement with the data and that A xx is especially sensitive to the D-state component of α-particle wave functions generated by different realistic nucleon-nucleon interactions

Microscopic calculation of the molecular-nuclear D+D → sup(3)He+n and D+D → sup(3)H+p reactions at close to zero energies

International Nuclear Information System (INIS)

Frederico, T.; Groote, J.J. de; Hornos, J.E.; Hussein, M.S.

1990-11-01

Microscopic calculations of the astrophysically interesting reactions D+D→sup(3)He+n and D+D→sup(3)H+p are performed using nuclear reaction theory and Born-Oppenheimer type molecular calculation of the D+D initial stage. The sensitivity of the fusion rate to the behaviour of the D+D wave function at close to zero separation is assessed. Relevance of the results to the cold fusion problem is discussed. (author)

Mechanism of the reactions 14N(d,p)15N and 14N(d,n)15O by Doppler shift line shape method

International Nuclear Information System (INIS)

Abdel-Moneim, A.M.

1976-06-01

In this investigation the total and the differential absolute cross sections of the 14 N(d,p) 15 N reaction leading to excited states at 7.3, 8.3 and 9.05 MeV levels in 15 N and the 14 N(d,n) 15 O reaction leading to the 6.79 MeV level in 15 O, have been studied over the energy range from 0.5 MeV to 3 MeV. Doppler shift line shape method as well as γ-ray yield measurements have been used. The absolute cross sections are determined relative to the known 14 N(p,p) elastic differential cross sections. A comparison with previously determined values for the same reactions at selected energies shows good agreement in angular distribution as well as in absolute values. The total cross section for the d,p reaction shows a general energy dependence which is typical for direct reactions, but with minor contribution from compound nucleus formation at certain energy ranges. For the 14 N(d,n) 15 N reaction, the method applied is unique, since it allows the differential cross section to be studied all the way down to the threshold energy of deuterons at 2 MeV, with a detectorsystem efficiency which is constant over the entire range of neutron energies. The larger part of the energy range that has been investigated is dominated by a resonance at 2.55 π+ 0.05 MeV deuteron energy and a halfwidth depending on the amount of contribution from the direct reaction of the order of 200-400 keV. (JIW)

Japan Nuclear Reaction Data Center (JCPRG), Faculty of Science, Hokkaido University, Steering Committee progress report

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-11-15

The Japan Nuclear Reaction Data Center (JCPRG) was approved as an organisation of Faculty of Science, Hokkaido University and established on April 1, 2007. In addition to nuclear data activities carried out by JCPRG (Japan-Charged Particle Nuclear Reaction Data Group), the centre is concerned with the evaluation of nuclear reaction data in nucleosynthesis in the universe. In order efficiently to compile reaction data obtained by using radioactive ion beam, the centre signed a research contract with RIKEN Nishina Center. We are scanning 16 journals for Japanese charged-particle and photo-nuclear nuclear reaction data compilation. From April 2006 to March 2007, CPND and PhND in 45 references (453 records, 1.83 MB) have been newly compiled for NRDF. Usually new data are released at the JCPRG web site several months prior to EXFOR. Since the 2006 NRDC meeting, we have made 104 new entries and have revised or deleted 142 old entries. Intensive numerical data compilations have been done. These data were shown in tabular form in dissertations which are (partially) published in Journals. About 30 new entries were compiled from these data. We have prepared CINDA batches for CPND published in Japan every half year. Each batch covers 6 issues of each of 4 Japanese journals JPJ, PTP, NST and JNRS. Bibliographies for neutron induced reaction data have been compiled by JAEA Nuclear Data Center as before. A new web-based NRDF search and plot system on MySQL was released in July, 2007. New compilation, which has been finalized for NRDF, but not for EXFOR, can be obtained from this site. DARPE (another NRDF search and plot system written in Perl) is also available at http://www.jcprg.org/darpe/. EXFOR/ENDF (http://www.jcprg.org/exfor/) search and plot system is available. We have also developed following utilities: PENDL (http://www.jcprg.org/endf/) and RENORM (http://www.jcprg.org/renorm). We are developing a new search system of CINDA. This is an extension of EXFOR/ENDF search

NNDC evaluated charged particle reaction data library (1975)

Energy Technology Data Exchange (ETDEWEB)

Pearlstein, S

1985-09-01

The US National Nuclear Data Center developed a `starter` library for charged particle induced nuclear reaction data in a trial ENDF/B format. It was issued in June 1974 and corrected in August 1975. It includes integral cross-section data for 306 nuclides between Z = 21 and 83 for the following reactions in the energy range from 0 to 20 MeV: (p,n); (p,2n); (p,3n); (d,n); (d,2n); (d,3n); (d,p); ({alpha},n); ({alpha},2n); ({alpha},3n); ({alpha},p) and ({alpha},np). The data were calculated following the nuclear systematics developed by J. Lange and H. Muenzel [KFK-767, May 19681]. The library serves to provide unmeasured cross sections and information that usually compares within an order of magnitude with actual data. It also serves as a convenient source for those requiring charged particle data in computerized form. The library contains 38,584 records. The following documentation is a reprint of a report by S. Pearlstein, BNL-19148, May 1974. (author) 6 refs, 12 figs

Drift-tube studies of ion-molecule reactions at low collision energies

International Nuclear Information System (INIS)

Chatterjee, B.K.

1988-01-01

This thesis presents experimental studies of ion-molecule reactions at low collision energies using two drift tube mass spectrometer apparatus. The reactions studied are (i) proton transfer from HeH + to ArH + , (ii) charge and ion transfer reactions of O 2 2+ with NO, CO 2 , Ne and O 2 + ( 4 π u ) with CO 2 , (iii) oxidation reactions of Zr + and ZrO + with NO, CO 2 and O 2 , (iv) vibrational quenching reactions of H 3 + with He, (v) termolecular clustering reactions of H 2 CN + and H 2 CN + (HCN) (with He as the third body), (vi) three body association reactions of H + and D + with He (with He as the third body) and (vii) termolecular association reaction of NO + with NO (with Ne as third body). All the reactions were studied at thermal energies (at room temperature), reactions of O 2 2+ with NO and CO 2 , Zr + with NO/CO 2 /O 2 were also studied at center-of-mass energies higher than thermal and the association reactions of H 2 CN + /H 2 CN + (HCN) with HCN and H + /D + with He were studied at low temperatures. In addition, the thesis presents model calculations for the sweep-out effect which is an instrumental effect. A super Langevin rate constant is introduced which is a higher-order correction to the Langevin model. A theoretical model for the three-body ion-atom association rate constant is presented in the appendix of the thesis

Oxidation of D-glucose and D-fructose with oxygen in aqueous, alkaline solutions. Part I. An integral reaction scheme

NARCIS (Netherlands)

de Wilt, H.G.J.; Kuster, B.F.M.

1971-01-01

The homogeneous oxidn. of D-glucose and D-fructose with O in aq., alk. solns. is studied, and a reaction scheme proposed to account for the obsd. reaction products. Formation of enolate anions is followed by non-oxidative reactions (involving double-bond migration and cleavage) and by oxidative

Cross sections of the O++H2→OH++H ion-molecule reaction and isotopic variants (D2, HD): Quasiclassical trajectory study and comparison with experiments

International Nuclear Information System (INIS)

Martinez, Rodrigo; Sierra, Jose Daniel; Gonzalez, Miguel

2005-01-01

A dynamics study [cross section and microscopic mechanism versus collision energy (E T )] of the reaction O + +H 2 →OH + +H, which plays an important role in Earth's ionosphere and interstellar chemistry, was conducted using the quasiclassical trajectory method, employing an analytical potential energy surface (PES) recently derived by our group [R. Martinez et al., J. Chem. Phys. 120, 4705 (2004)]. Experimental excitation functions for the title reaction, as well as its isotopic variants with D 2 and HD, were near-quantitatively reproduced in the calculations in the very broad collision energy range explored (E T =0.01-6.0 eV). Intramolecular and intermolecular isotopic effects were also examined, yielding data in good agreement with experimental results. The reaction occurs via two microscopic mechanisms (direct and nondirect abstraction). The results were satisfactorily interpreted based on the reaction probability and the maximum impact parameter dependences with E T , and considering the influence of the collinear [OHH] + absolute minimum of the PES on the evolution from reactants to products. The agreement between theory and experiment suggests that the reaction mainly occurs through the lowest energy PES and nonadiabatic processes are not very important in the wide collision energy range analyzed. Hence, the PES used to describe this reaction is suitable for both kinetics and dynamics studies

Quantum approaches for the insertion dynamics of the H++D2 and D++H2 reactive collisions

International Nuclear Information System (INIS)

Gonzalez-Lezana, Tomas; Aguado, Alfredo; Paniagua, Miguel; Roncero, O.

2005-01-01

The H + +D 2 and D + +H 2 reactive collisions are studied using a recently proposed adiabatic potential energy surface of spectroscopic accuracy. The dynamics is studied using an exact wave packet method on the adiabatic surface at energies below the curve crossing occurring at ≅1.5 eV above the threshold. It is found that the reaction is very well described by a statistical quantum method for a zero total angular momentum (J) as compared with the exact ones, while for higher J some discrepancies are found. For J>0 different centrifugal sudden approximations are proposed and compared with the exact and statistical quantum treatments. The usual centrifugal sudden approach fails by considering too high reaction barriers and too low reaction probabilities. A new statistically modified centrifugal sudden approach is considered which corrects these two failures to a rather good extent. It is also found that an adiabatic approximation for the helicities provides results in very good agreement with the statistical method, placing the reaction barrier properly. However, both statistical and adiabatic centrifugal treatments overestimate the reaction probabilities. The reaction cross sections thus obtained with the new approaches are in rather good agreement with the exact results. In spite of these deficiencies, the quantum statistical method is well adapted for describing the insertion dynamics, and it is then used to evaluate the differential cross sections

P-d capture reactions in muonic molecules

International Nuclear Information System (INIS)

Friar, J.L.

1991-01-01

Capture reactions for very low-energy n-d and p-d systems are calculated and compared with experiment, as are low-energy n-d and p-d scattering. We find excellent agreement for the n-d scattering lengths, but poor agreement for the p-d case, which we believe is a problem with the experimental extrapolation. The n-d radiative capture is sensitive to details of the meson-exchange currents, but reasonable models agree with the data. The latter models are in good agreement with experiment when extended to the p-d case. Our large quartet capture rate resolves a long-standing anomaly. The EO capture matrix element recently obtained from a reanalysis of internal conversion in muonic molecules is in excellent agreement with our predictions. This matrix element is very clean theoretically and provides the best test of the calculations. 33 refs., 3 figs., 1 tab

The dynamics of the reaction of 16O(1D)+D218O→16OD+18OD

International Nuclear Information System (INIS)

Guillory, W.A.; Gericke, K.H.; Comes, F.J.

1983-01-01

The detailed energy partitioning in the reaction of a metastable oxygen atom O( 1 D) with D 2 O proceeding to two OD molecules has been studied. In order to distinguish the product state distribution between the two chemically identical product molecules OD, the oxygen atom in the heavy water molecule was labeled isotopically. The use of spectroscopic methods allows a complete analysis of the products' state distribution including such fine details as the distribution of the different #betta# components and of the electron spin. The vibrational energy is almost exclusively channeled into the new ( 16 OD) bond, whereas the original ( 18 OD) bond is produced (>90%) in the ground vibrational state. Both OD radicals show a broad rotational excitation and the rotational energy is equally partitioned among the two bonds. The energy distribution over the rovibrational levels strongly reflects the influence of coincident product molecules emerging from this chemical reaction. The reaction is very direct and must proceed on a time scale which does not allow for efficient energy transfer into all the available phase space

Interaction of charged 3D soliton with Coulomb center

International Nuclear Information System (INIS)

Rybakov, Yu.P.

1996-03-01

The Einstein - de Broglie particle-soliton concept is applied to simulate stationary states of an electron in a hydrogen atom. According to this concept, the electron is described by the localized regular solutions to some nonlinear equations. In the framework of Synge model for interacting scalar and electromagnetic fields a system of integral equations has been obtained, which describes the interaction between charged 3D soliton and Coulomb center. The asymptotic expressions for physical fields, describing soliton moving around the fixed Coulomb center, have been obtained with the help of integral equations. It is shown that the electron-soliton center travels along some stationary orbit around the Coulomb center. The electromagnetic radiation is absent as the Poynting vector has non-wave asymptote O(r -3 ) after averaging over angles, i.e. the existence of spherical surface corresponding to null Poynting vector stream, has been proved. Vector lines for Poynting vector are constructed in asymptotical area. (author). 22 refs, 2 figs

Model of deep centers formation and reactions in electron irradiated InP

International Nuclear Information System (INIS)

Sibille, A.; Suski, J.; Gilleron, M.

1986-01-01

We present a model of the production of deep centers and their reactions following electron irradiations in InP. We propose that the dominant hole traps in p-InP and electron traps in p + n InP junctions are complexes between shallow acceptors and a common intrinsic entity, the phosphorus interstitial or vacancy. The reactions observed below and above room temperature are then due to a local mobility of this entity, which can be obtained as well by thermal as by electronic stimulation of the reactions. This model implies the long-range migration (at least down to 16 K) of this entity, and explains the strongly different behavior of n-InP compared to p-InP samples

Contribution to the study of low-energy (d,p) reactions on light nuclei; Contribution a l'etude des reactions (d,p) a basse energie sur noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Nguyen Van, S [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-05-15

This work is carried out with a view to analysing low energy (d,p) reactions on light nuclei measured at Grenoble or Algiers and suggesting a direct mechanism. The distorted wave approximation has been applied; this requires the development of programmes for the IBM 7044 computer at the 'Institut des Mathematiques Appliquees' in Grenoble. The (d,p) reactions on {sup 14}N, {sup 9}Be, {sup 22}Ne and {sup 16}O are dealt with. A calculation of the interference of the direct interaction and of resonating effects has been applied to {sup 16}O. (author) [French] Ce travail a pour but d'analyser les reactions (d,p) a basse energie sur noyaux legers, mesurees a Grenoble ou a Alger et qui suggerent un mecanisme direct. L'approximation des ondes distordues a ete appliquee, necessitant la mise au point de programmes sur l'ordinateur IBM 7044 de l'Institut des Mathematiques Appliquees de Grenoble. Des reactions (d,p) sur {sup 14}N, {sup 9}Be, {sup 22}Ne et {sup 16}O sont traitees. Un calcul de l'interference de l'interaction directe et des effets resonnants a ete applique a {sup 16}O. (auteur)

Kinetics of exchange reaction between neodymium(3) transcyclohexanediaminetetraacetate and europium(3)- and holmium(3) aquo-ions in the H2O and D2O solutions

International Nuclear Information System (INIS)

Nikitenko, S.I.; Martynenko, L.I.; Pechurova, N.I.; Spitsyn, V.I.

1983-01-01

The exchange reaction between central ions in the NdD - Ln' 3+ systems, where Ln' 3+ is a substituting cation (Eu 3+ and Ho 3+ , D 4 =cyclohexanediaminetetraacetate) is studied and the electrophilic suhstitution mechanism is considered. To study the kinetic isotope effects, the reagents have been solVed in heavy water containing 99.9% D 2 O. The electrophilic substitution in the indicated systems proceeds through the dissociative mechanism catalyzed by protons and via the spontaneous dissociation mechanism. The exchange via the acid-catalyzed mechanism is limited by the intermediate protonated complex decay. The associative mechanism of the electrophilic exchange in the studied systems is not realized

Isotope exchange reaction in Li2ZrO3 packed bed

International Nuclear Information System (INIS)

Kawamura, Y.; Enoeda, M.; Okuno, K.

1998-01-01

To understand the release behavior of bred tritium in a solid breeder blanket, the tritium transfer rate and tritium inventory for various mass transfer processes should be investigated. The contribution of the surface reactions (adsorption, desorption and two kinds of isotope exchange reactions) to the release process cannot be ignored. It is believed that two kinds of isotope exchange reactions (gaseous hydrogen-tritiated water and water vapor-tritiated water) occur on the surface of the solid breeder materials when hydrogen is added to the sweep gas to enhance the tritium release rate. The isotope exchange reaction study in H-D systems was carried out using a Li 2 ZrO 3 packed bed. The exchange reaction between gaseous hydrogen and water was the rate controlling step among the two kinds of exchange reactions. The reaction rate constants were quantified, and experimental equations were proposed. The equilibrium constant of the isotope exchange reaction in the H-D system was obtained from experimental data and was found to be 1.17. (orig.)

Cross section measurement and integral test for several activation reactions using T + d and thick-Li + d sources

International Nuclear Information System (INIS)

Dumais, J.R.; Tanaka, S.; Odano, N.; Iwasaki, S.; Sugiyama, K.

1988-01-01

Recent activities on the area of the cross section measurement for several activation reactions at Department of Nucl. Eng., Tohoku Univ. are described. The first subject is the cross section measurement for (n,2n) reaction on aluminum using the RTNS-II neutron source. Cross sections with rather small error band were obtained for the incident neutron energies from 14 to 14.7 MeV. The second one is the status of the program for the integral experiments on several reactions using the thick Li + d source at Tohoku Fast Neutron Lab. The experimental results showed the usefullness of the source as a tool for the cross section assessment. (author)

Kinetics of transuranium element oxidation-reduction reactions in solution; Cinetique des reactions d'oxydo-reduction des elements transuraniens en solution

Energy Technology Data Exchange (ETDEWEB)

Gourisse, D [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1966-09-01

A review of the kinetics of U, Np, Pu, Am oxidation-reduction reactions is proposed. The relations between the different activation thermodynamic functions (compensatory effect, formal entropy of the activated complex, magnitude of reactions velocities) are considered. The effects of acidity, ionic strength deuterium and mixed solvents polarity on reactions rates are described. The effect of different anions on reactions rates are explained by variations of the reaction standard free energy and variations of the activation free energy (coulombic interactions) resulting from the complexation of dissolved species by these anions. (author) [French] Une revue systematique de la cinetique des reactions d'oxydo-reduction des elements U, Np, Pu, Am, en solution perchlorique est proposee. Des considerations relatives aux grandeurs thermodynamiques d'activation associees aux actes elementaires (effet de compensation, entropie standard des complexes actives, rapidite des reactions) sont developpees. L'influence de l'acidite, de la force ionique, de l'eau lourde et de la polarite des solvants mixtes sur la vitesse des reactions est decrite. Enfin l'influence des differents anions sur la vitesse des reactions est expliquee par les variations de l'enthalpie libre standard de la reaction et de l'enthalpie libre d'activation (travail des forces electrostatiques) resultant de la complexation des especes dissoutes dans la solution. (auteur)

X-ray and EPR study of reactions between B4C and TiO2

International Nuclear Information System (INIS)

Kakazey, M.; Vlasova, M.; Gonzalez-Rodriguez, J.G.; Dominguez-Patino, M.; Leder, R.

2006-01-01

X-ray diffraction and electron paramagnetic resonance (EPR) methods have been used to study the reaction process in a system of 95 wt.% of B 4 C + 5 wt.% TiO 2 . The addition of TiO 2 to B 4 C was effective in accelerating the removal of carbon inclusions. Two types of reactions between B 4 C and TiO 2 , starting at temperatures ∼1173 K, took place: (a) gas-transport exchange and (b) diffusion of Ti atoms into the B 4 C lattice. These reactions modify the number and type of donor centers in the B 4 C. The dependence of EPR line width on the number of donor centers in B 4 C (from conditions of sample treatment) is a useful method for investigating the formation of powders and ceramics based on B 4 C

Gamma diagnostics of thermonuclear plasma using D(d, gamma)4He reaction: Feasibility study

International Nuclear Information System (INIS)

Robouch, B.V.; Brzosko, J.S.; Ingrosso, L.

1993-01-01

Recent measurements of the D(d, Y) 4 He (Ey=25 MeV) reaction cross-section at low energies indicate values about 3 orders of magnitude higher than those obtained through extrapolations of previous experimental data. The new information triggers interest in the use of 25 MeV photons for diagnostics of fusion plasma. Both the spectral broadening of the neutron emission from the D(d, n)-reaction and that of the of the 25 MeV Gamma line offer two sensitive methods for the measurement of plasma temperature. Implementing this method presents an advantage over the classical neutron spectra broadening ((d, n)-branch) since it is simpler, more compact and cheaper. Moreover, once the necessary enhancement of the Y/n ratio is ensured, other complementary Y-diagnostics (under intense neutron fluxes) become possible. A preliminary version of such a system was developed using the 3D-MCSC-RWR subroutine complex of Monte Carlo random walk. The detecting system, composed of a HPGe-detector surrounded by a multilayer shield, appears to be very promising

Structure of 14C and 14B from the C,1514(d ,3He)B,1413 reactions

Science.gov (United States)

Bedoor, S.; Wuosmaa, A. H.; Albers, M.; Alcorta, M.; Almaraz-Calderon, Sergio; Back, B. B.; Bertone, P. F.; Deibel, C. M.; Hoffman, C. R.; Lighthall, J. C.; Marley, S. T.; Mcneel, D. G.; Pardo, R. C.; Rehm, K. E.; Schiffer, J. P.; Shetty, D. V.

2016-04-01

We have studied the C,1514(d ,3He)B,1413 proton-removing reactions in inverse kinematics. The (d ,3He ) reaction probes the proton occupation of the target ground state, and also provides spectroscopic information about the final states in B,1413. The experiments were performed using C,1514 beams from the ATLAS accelerator at Argonne National Laboratory. The reaction products were analyzed with the HELIOS device. Angular distributions were obtained for transitions from both reactions. The 14C-beam data reveal transitions to excited states in 13B that suggest configurations with protons outside the π (0 p3 /2) orbital, and some possibility of proton cross-shell 0 p -1 s 0 d excitations, in the 14C ground state. The 15C-beam data confirm the existence of a broad 2- excited state in 14B. The experimental data are compared to the results of shell-model calculations.

NASA Glenn Research Center Experience with "LENR Phenomenon"

Science.gov (United States)

Wrbanek, Susan Y.; Fralick, Gustave C.; Wrbanek, John D.; Niedra, Janis M.

2012-01-01

Since 1989 NASA Glenn Research Center (GRC) has performed some small-scale limited experiments that show evidence of effects claimed by some to be evidence of Low Energy Nuclear Reactions (LENR). The research at GRC has involved observations and work on measurement techniques for observing the temperature effects in reactions of isotopes of hydrogen with palladium hydrides. The various experiments performed involved loading Pd with gaseous H2 and D2, and exposing Pd thin films to multi-bubble sonoluminescence in regular and deuterated water. An overview of these experiments and their results will be presented.

NASA Glenn Research Center Experience with LENR Phenomenon

Science.gov (United States)

Wrbanek, Susan Y.; Fralick, Gustave C.; Wrbanek, John D.; Niedra, Janis M.

2012-01-01

Since 1989 NASA Glenn Research Center (GRC) has performed some small-scale limited experiments that show evidence of effects claimed by some to be evidence of Low Energy Nuclear Reactions (LENR). The research at GRC has involved observations and work on measurement techniques for observing the temperature effects in reactions of isotopes of hydrogen with palladium hydrides. The various experiments performed involved loading Pd with gaseous H2 and D2, and exposing Pd thin films to multi-bubble sonoluminescence in regular and deuterated water. An overview of these experiments and their results will be presented.

Direct Dynamics Simulation of the Thermal 3CH2 + 3O2 Reaction. Rate Constant and Product Branching Ratios.

Science.gov (United States)

Lakshmanan, Sandhiya; Pratihar, Subha; Machado, Francisco Bolivar Correto; Hase, William Louis

2018-04-26

The reaction of 3CH2 with 3O2 is of fundamental importance in combustion and the reaction is complex as a result of multiple extremely exothermic product channels. In the present study, direct dynamics simulations were performed to study the reaction on both the singlet and triplet potential energy surfaces (PESs). The simulations were performed at the UM06/6-311++G(d,p) level of theory. Trajectories were calculated at a temperature of 300 K and all reactive trajectories proceeded through the carbonyl oxide Criegee intermediate, CH2OO, on both the singlet and triplet PESs. The triplet surface leads to only one product channel, H2CO + O(3P), while the singlet surface leads to 8 product channels with their relative importance as: CO + H2O > CO + OH + H ~ H2CO + O(1D) > HCO + OH ~ CO2 + H2 ~ CO + H2 + O(1D) > CO2 + H + H > HCO + O(1D) + H. Reaction on the singlet PES is barrierless, consistent with experiment and the total rate constant on the singlet surface is 0.93 ± 0.22 x 10-12 cm3molecule-1s-1 in comparison to the recommended experimental rate constant of 3.3 x 10-12 cm3molecule-1s-1. The simulation product yields for the singlet PES are compared with experiment and the most significant differences are for H, CO2, and H2O. Reaction on the triplet surface is also barrierless, inconsistent with experiment. A discussion is given of the need for future calculations to address the: (1) barrier on the triplet PES for 3CH2 + 3O2 → 3CH2OO; (2) temperature dependence of the 3CH2 + 3O2 reaction rate constant and product branching ratios; and (3) possible non-RRKM dynamics of the 1CH2OO Criegee intermediate.

Radiative d–d transitions at tungsten centers in II–VI semiconductors

Energy Technology Data Exchange (ETDEWEB)

Ushakov, V. V., E-mail: ushakov@lebedev.ru; Krivobok, V. S.; Pruchkina, A. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2017-03-15

The luminescence spectra of W impurity centers in II–VI semiconductors, specifically, ZnSe, CdS, and CdSe, are studied. It is found that, if the electron system of 5d (W) centers is considered instead of the electron system of 3d (Cr) centers, the spectral characteristics of the impurity radiation are substantially changed. The electron transitions are identified in accordance with Tanabe–Sugano diagrams of crystal field theory. With consideration for the specific features of the spectra, it is established that, in the crystals under study, radiative transitions at 5d W centers occur between levels with different spins in the region of a weak crystal field.

The Knoevenagel-Doebner Reaction on 1,2-O-(2,2,2-Trichloroethylidene Derivatives of D-Gluco- and D-Manno- furanose

Directory of Open Access Journals (Sweden)

Gökhan Kök

2010-10-01

Full Text Available The synthesis of new α,β-unsaturated furanuronic acid derivatives of α-gluco- (3, β-gluco- (6 and β-manno-chloraloses (9 via a convenient one pot procedure using the Knoevenagel-Doebner reaction approach are described. The dialdofuranose derivatives were reacted with malonic acid under Knoevenagel-Doebner reaction conditions and (E-α,β-unsaturated furanuronic acid derivatives were obtained.

DFT studies on the multi-channel reaction of CH3S+NO2

Science.gov (United States)

Tang, Yi-Zhen; Sun, Hao; Pan, Ya-Ru; Pan, Xiu-Mei; Wang, Rong-Shun

The mechanisms for the reaction of CH3S with NO2 are investigated at the QCISD(T)/6-311++G(d,p)//B3LYP/6-311++G(d,p) on both single and triple potential energy surfaces (PESs). The geometries, vibrational frequencies, and zero-point energy (ZPE) correction of all stationary points involved in the title reaction are calculated at the B3LYP/6-311++G(d,p) level. More accurate energies are obtained at the QCISD(T)/6-311++G(d,p). The results show that 5 intermediates and 14 transition states are found. The reaction is more predominant on the single PES, while it is negligible on the triple PES. Without any barrier height for the whole process, the main channel of the reaction is to form CH3SONO and then dissociate to CH3SO+NO.

Selected ion flow tube (SIFT) studies of the reactions of H3O+, NO+ and O-2(+center dot) with six volatile phytogenic esters

Czech Academy of Sciences Publication Activity Database

Sovová, K.; Dryahina, Kseniya; Španěl, Patrik

2011-01-01

Roč. 300, č. 1 (2011), s. 31-38 ISSN 1387-3806 R&D Projects: GA ČR GA202/09/0800; GA ČR GA203/09/0256 Institutional research plan: CEZ:AV0Z40400503 Keywords : SIFT-MS * ion-molecule reactions * plant esters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.549, year: 2011

Asymmetric Alkylation and Aldol Reactions of D-Mannitol-Derived Chiral Oxazolidin-2-one Derivatives

International Nuclear Information System (INIS)

Maeng, Yun Hee; Jun, Jong Gab

2004-01-01

In the preceding article, we have introduced a new chiral oxazolidin-2-one auxiliary (1) derived from a cheap Dmannitol, and demonstrated the chiral selectivity in alkylation, aldol reaction and β-lactam synthesis.1 The present work began with a search for useful chiral directing groups with which to control the chiral selectivity. Because the rigidity of cyclic structures contributes significantly to control of chirality,2 the 1,2:5,6-di-O-cyclohexylidene-Dmannitol (2) was used for the synthesis of oxazolidin-2-one chiral auxiliary (3) comparing the selectivity with the auxiliary (1) in alkylation and aldol reactions.

Some new effects of the deuteron D state observed in (p,d) and (d,p) reactions

International Nuclear Information System (INIS)

Ohnuma, Hajime

1980-01-01

Two previously unexplored experiments have revealed the importance of the deuteron D-state effects on (p,d) and (d,p) reactions at moderate energies. Firstly, a clear indication of the deuteron D-state effects on the polarization of the residual nuclear state has been observed in the 58 Ni(p,dγ) angular correlation measurement at E sub(p) = 30 MeV. Secondly, a comparison of the vector analyzing power and vector polarization measured at E sub(d) = 22 MeV for an l = 0 (d,p) transition has shown that the D state has significant effects even on the first-rank polarization quantities. The experimental data and the results of exact-finite-range DWBA calculations with Reid soft-core potential are presented. (author)

Measurement of the 2H(7Be, 6Li)3He reaction rate and its contribution to the primordial lithium abundance

Science.gov (United States)

Li, Er-Tao; Li, Zhi-Hong; Yan, Sheng-Quan; Su, Jun; Guo, Bing; Li, Yun-Ju; Wang, You-Bao; Lian, Gang; Zeng, Sheng; Chen, Si-Zhe; Ma, Shao-Bo; Li, Xiang-Qing; He, Cao; Sun, Hui-Bin; Liu, Wei-Ping

2018-04-01

In the standard Big Bang nucleosynthesis (SBBN) model, the lithium puzzle has attracted intense interest over the past few decades, but still has not been solved. Conventionally, the approach is to include more reactions flowing into or out of lithium, and study the potential effects of those reactions which were not previously considered. 7Be(d, 3He)6Li is a reaction that not only produces 6Li but also destroys 7Be, which decays to 7Li, thereby affecting 7Li indirectly. Therefore, this reaction could alleviate the lithium discrepancy if its reaction rate is sufficiently high. However, there is not much information available about the 7Be(d, 3He)6Li reaction rate. In this work, the angular distributions of the 7Be(d, 3He)6Li reaction are measured at the center of mass energies E cm = 4.0 MeV and 6.7 MeV with secondary 7Be beams for the first time. The excitation function of the 7Be(d, 3He)6Li reaction is first calculated with the computer code TALYS and then normalized to the experimental data, then its reaction rate is deduced. A SBBN network calculation is performed to investigate its influence on the 6Li and 7Li abundances. The results show that the 7Be(d, 3He)6Li reaction has a minimal effect on 6Li and 7Li because of its small reaction rate. Therefore, the 7Be(d, 3He)6Li reaction is ruled out by this experiment as a means of alleviating the lithium discrepancy. Supported by National Natural Science Foundation of China (11375269, 11505117, 11490560, 11475264, 11321064), Natural Science Foundation of Guangdong Province (2015A030310012), 973 program of China (2013CB834406) and National key Research and Development Province (2016YFA0400502)

Coupled-reaction-channel analysis of the (d,6Li) reaction on 24Mg and 26Mg to low-lying states

International Nuclear Information System (INIS)

Oelert, W.

1986-01-01

Experimental spectroscopic factors of the alpha-transfer reaction on nuclei of the sd-shell show rather strong inconsistencies and scatter much more strongly than explainable by the quoted errors. The poorer the quality of agreement between experimental and theoretical angular distribution shapes, the more inconsistent the comparison of spectroscopic factors either between different experiments or between theory and experiment. In view of the strong deformation of nuclei in the lower part of the sd-shell, higher-order reaction mechanisms are expected. A coupled-reaction-channel analysis for the transitions to the 0 + , 2 + , and 4 + states of the ground-state bands in 20 Ne and 22 Ne excited via the (d, 6 Li) reaction yields good agreement between experimental and theoretical angular distribution shapes as well as spectroscopic information. (orig.)

Search for a resonant enhancement of the 7Be + d reaction and primordial 7Li abundances

International Nuclear Information System (INIS)

O'Malley, Patrick; Adekola, A.S.; Cizewski, J.A.; Howard, M.E.; Strauss, S.; Bardayan, Daniel W.; Chae, Kyung Yuk; Nesaraja, Caroline D.; Pain, Steven D.; Smith, Michael Scott; Ahn, S.H.; Jones, K.L.; Pittman, S.T.; Schmitt, Kyle; Graves, S.; Kozub, R.L.; Shriner, J.F. Jr.; Wheeler, J.L.; Linhardt, Laura; Matos, M.; Moazen, B.M.; Peters, W.A.; Spassova, I.

2011-01-01

Big Bang nucleosynthesis calculations, constrained by the Wilkinson Microwave Anisotropy Probe results, produce 7 Li abundances almost a factor of four larger than those extrapolated from observations. Since primordial 7 Li is believed to be mostly produced by the beta decay of 7 Be, one proposed solution to this discrepancy is a resonant enhancement of the 7 Be(d,p)2α reaction rate through the 5/2 + 16.7-MeV state in 9 B. The 2 H( 7 Be,d) 7 Be reaction was used to search for such a resonance; none was observed. An upper limit on the width of the proposed resonance was deduced.

Implantation of energetic D{sup +} ions into carbon dioxide ices and implications for our solar system: formation of D{sub 2}O and D{sub 2}CO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Bennett, Chris J.; Ennis, Courtney P.; Kaiser, Ralf I., E-mail: ralfk@hawaii.edu [Department of Chemistry, University of Hawai' i at Mānoa, Honolulu, HI 96822 (United States)

2014-10-10

Carbon dioxide (CO{sub 2}) ices were irradiated with energetic D{sup +} ions to simulate the exposure of oxygen-bearing solar system ices to energetic protons from the solar wind and magnetospheric sources. The formation of species was observed online and in situ by exploiting FTIR spectroscopy. Molecular products include ozone (O{sub 3}), carbon oxides (CO{sub 3}(C {sub 2v}, D {sub 3h}), CO{sub 4}, CO{sub 5}, CO{sub 6}), D2-water (D{sub 2}O), and D2-carbonic acid (D{sub 2}CO{sub 3}). Species released into the gas phase were sampled via a quadrupole mass spectrometer, and possible minor contributions from D2-formaldehyde (D{sub 2}CO), D4-methanol (CD{sub 3}OD), and D2-formic acid (DCOOD) were additionally identified. The feasibility of several reaction networks was investigated by determining their ability to fit the observed temporal column densities of 10 key species that were quantified during the irradiation period. Directly relevant to the CO{sub 2}-bearing ices of comets, icy satellites in the outer solar system, and the ice caps on Mars, this work illustrates for the first time that D2-water is formed as a product of the exposure of CO{sub 2} ices to D{sup +} ions. These findings provide strong support for water formation from oxygen-bearing materials via non-thermal hydrogen atoms, and predict reaction pathways that are likely to be unfolding on the surfaces of asteroids and the Moon.

Tritiated-water detection with a 2D(γ,n)1H monitor

International Nuclear Information System (INIS)

Winn, W.G.; Baumann, N.P.

Tritiated process water is monitored by detecting the D 2 O component via the 2 D(γ,n) 1 H reaction. A probe containing a 1 to 7 mCi 24 Na (15 h) γ-source and six 3 He neutron detectors produces and monitors the 2 D(γ,n) 1 H reaction. A variety of probe configurations were examined for D 2 O detection sensitivity. The corresponding detection limits range from 6 to 280 μL for D 2 O droplets and 1 to 13 μL/cm for D 2 O streams, when 10-minute neutron counting with a 1 mCi γ-source is used. Results from two field applications illustrate the utility of the monitor

TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER

Energy Technology Data Exchange (ETDEWEB)

Westbrook, M.; Becnel, J.; Garrison, S.

2010-02-25

The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction

Cross sections for ion production in reactions of H+ with D2; Effects of vibrational and rotational excited states of D2

OpenAIRE

市原 晃; 岩本 修; 横山 啓一

1998-01-01

H+とD2の反応で生じるD2+,D+及びHD+イオン生成の断面積を、重心衝突エネルギーEcm=2.5-8.0eVの範囲内で、非経験的分子軌道計算で得られたH3+の3次元ポテンシャル面上でのトラジェクトリーサーフェスホッピング(TSH)法を用いることにより、評価した。反応物D2の初期状態が各イオン生成に与える影響を調べるために、D2の振動及び回転の量子数をv=0-3,j=1,5,10に設定して計算を行った。その結果、D2+イオンの生成は、D2の振動回転状態(v,j)が高くなるに従って著しく増大することが分かった。D2+生成の飛躍的な増大には、D2の振動励起が主要な役割を果たし、回転励起は補助的な効果を与えた。D2+生成と比較して、D2の振動状態がD+及びHD+イオンの生成に与える効果は一桁小さく、D2の回転状態に対する効果は殆ど無視しうる大きさであった。...

Ultrafast, 2 min synthesis of monolayer-protected gold nanoclusters (d < 2 nm)

Science.gov (United States)

Martin, Matthew N.; Li, Dawei; Dass, Amala; Eah, Sang-Kee

2012-06-01

An ultrafast synthesis method is presented for hexanethiolate-coated gold nanoclusters (d gold nanoclusters are separated from the reaction byproducts fast and easily without any need for post-synthesis cleaning.An ultrafast synthesis method is presented for hexanethiolate-coated gold nanoclusters (d gold nanoclusters are separated from the reaction byproducts fast and easily without any need for post-synthesis cleaning. Electronic supplementary information (ESI) available: Experimental details of gold nanocluster synthesis and mass-spectrometry. See DOI: 10.1039/c2nr30890h

Half-metallicity in 2D organometallic honeycomb frameworks

Science.gov (United States)

Sun, Hao; Li, Bin; Zhao, Jin

2016-10-01

Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule—CN—noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology.

Half-metallicity in 2D organometallic honeycomb frameworks

International Nuclear Information System (INIS)

Sun, Hao; Li, Bin; Zhao, Jin

2016-01-01

Half-metallic materials with a high Curie temperature (T C ) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d – p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule—CN—noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology. (paper)

3D staggered Lagrangian hydrodynamics scheme with cell-centered Riemann solver-based artificial viscosity

International Nuclear Information System (INIS)

Loubere, Raphael; Maire, Pierre-Henri; Vachal, Pavel

2013-01-01

The aim of the present work is the 3D extension of a general formalism to derive a staggered discretization for Lagrangian hydrodynamics on unstructured grids. The classical compatible discretization is used; namely, momentum equation is discretized using the fundamental concept of subcell forces. Specific internal energy equation is obtained using total energy conservation. The subcell force is derived by invoking the Galilean invariance and thermodynamic consistency. A general form of the subcell force is provided so that a cell entropy inequality is satisfied. The subcell force consists of a classical pressure term plus a tensorial viscous contribution proportional to the difference between the node velocity and the cell-centered velocity. This cell-centered velocity is an extra degree of freedom solved with a cell-centered approximate Riemann solver. The second law of thermodynamics is satisfied by construction of the local positive definite subcell tensor involved in the viscous term. A particular expression of this tensor is proposed. A more accurate extension of this discretization both in time and space is also provided using a piecewise linear reconstruction of the velocity field and a predictor-corrector time discretization. Numerical tests are presented in order to assess the efficiency of this approach in 3D. Sanity checks show that the 3D extension of the 2D approach reproduces 1D and 2D results. Finally, 3D problems such as Sedov, Noh, and Saltzman are simulated. (authors)

The first 3D malonate bridged copper [Cu(O{sub 2}C-CH{sub 2}-CO{sub 2}H){sub 2}{center_dot}2H{sub 2}O]: Structure, properties and electronic structure

Energy Technology Data Exchange (ETDEWEB)

Seguatni, A., E-mail: seguatni@gmail.com [LBPC-INSERM U 698, Institut Galilee, Universite Paris XIII, 99, avenue J. B. Clement 93430, Villetaneuse (France); Fakhfakh, M. [Unite de recherche UR 12-30, Synthese et Structure de Materiaux Inorganiques, Faculte des Sciences de Bizerte, 7021 Zarzouna (Tunisia); Departement de Chimie, Universite du Quebec a Montreal, C.P. 8888, Succ. Centre-ville, Montreal, Que., H3C 3P8 (Canada); Smiri, L.S. [Unite de recherche UR 12-30, Synthese et Structure de Materiaux Inorganiques, Faculte des Sciences de Bizerte, 7021 Zarzouna (Tunisia); Gressier, P.; Boucher, F. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 3 (France); Jouini, N. [Departement de Chimie, Universite du Quebec a Montreal, C.P. 8888, Succ. Centre-ville, Montreal, Que., H3C 3P8 (Canada)

2012-03-15

A new inorganic-organic compound [Cu(O{sub 2}C-CH{sub 2}-CO{sub 2}H){sub 2}{center_dot}2H{sub 2}O] ([Cumal]) was hydrothermally synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffraction. [Cumal] is the first three-dimensional compound existing in the system Cu(II)-malonic acid-H{sub 2}O. Its framework is built up through carboxyl bridged copper where CuO{sub 6} octahedra are elongated with an almost D{sub 4h} symmetry (4+2) due to the Jahn-Teller effect. The magnetic properties were studied by measuring its magnetic susceptibility in the temperature range of 2-300 K indicating the existence of weak ferromagnetic interactions. The electronic structure of [Cumal] was calculated within the density functional theory (DFT) framework. Structural features are well reproduced using DFT structural optimizations and the optical spectra, calculated within the dielectric formalism, explain very well the light blue colour of the compound. It is shown that a GGA+U approach with a U{sub eff} value of about 6 eV is necessary for a better correlation with the experiment. - Graphical abstract: [Cu(O{sub 2}C-CH{sub 2}-CO{sub 2}H){sub 2}{center_dot}2H{sub 2}O]: the first 3D hybrid organic-inorganic compound built up carboxyl groups. The network presents a diamond-like structure achieved via carboxyl. Highlights: Black-Right-Pointing-Pointer A new organic-inorganic material with an unprecedented topology is synthesized. Black-Right-Pointing-Pointer Crystallographic structure is determined using single crystal X-ray diffraction. Black-Right-Pointing-Pointer Electronic structure is obtained from DFT, GGA+U calculation. Black-Right-Pointing-Pointer Framework can be described as formed from CuC{sub 4} tetrahedron sharing four corners. Black-Right-Pointing-Pointer This structure can be classified as an extended diamond structure.

Study of the reaction D(p,π+)T at T/sub p/ = 410, 605, and 809 MeV

International Nuclear Information System (INIS)

Aslanides, E.; Bertini, R.; Bing, O.; Brochard, F.; Gorodetzky, P.; Hibou, F.; Bauer, T.S.; Beurtey, R.; Boudard, A.; Bruge, G.; Catz, H.; Chaumeaux, A.; Couvert, P.; Duhm, H.H.; Garreta, D.; Igo, G.; Lugol, J.C.; Matoba, M.; Terrien, Y.; Bimbot, L.; Le Bornec, Y.; Tatischeff, B.

1977-01-01

Pion production on a CD 2 target has been measured using the high-resolution magnetic spectrometer SPES I. Differential cross section for the reaction D(p,π + )T have been determined at T/sub p/ = 410, 605, and 809 MeV. The present data, together with previous results establish a complete angular distribution of the reaction D(p,π + )T at approx. 600 MeV and energy dependence of the differential cross section for this reaction at several constant momentum transfers

Biological diversity of photosynthetic reaction centers and the solid-state photo-CIDNP effect

NARCIS (Netherlands)

Roy, Esha

2007-01-01

Photosynthetic reaction centers (RCs) from plants, heliobacteria and green sulphur bacteria has been investigated with photochemically induced dynamic nuclear polarization (photo-CIDNP) MAS NMR. In photosystem (PS) I of spinach, all signals appear negative which is proposed by a predominance of the

Center type performance of differentiable vector fields in R2

International Nuclear Information System (INIS)

Rabanal, Roland

2007-08-01

Let X : R 2 / D → R 2 be a differentiable vector field, where D is compact. If the eigenvalues of the jacobian matrix DX z are (nonzero) purely imaginary, for all z element of R 2 / D . Then, X + v has a center type performance at infinity, for some v element of R 2 . More precisely, X + v has a periodic trajectory Γ subset of R2/ D which is surrounding D such that in the unbounded component of (R 2 / D )/ Γ all the trajectories of X + v are nontrivial cycles. In the case of global vector fields Y : R 2 → R 2 with Y (0) = 0, we prove that such eigenvalue condition implies the topological equivalency of Y with the linear vector field (x, y) → (-y, x). (author)

Obtaining the neutron time-of-flight instrument response function for a single D-T neutron utilizing n-alpha coincidence from the d(t, α) n nuclear reaction

Science.gov (United States)

Styron, Jedediah; Ruiz, Carlos; Hahn, Kelly; Cooper, Gary; Chandler, Gordon; Jones, Brent; McWatters, Bruce; Smith, Jenny; Vaughan, Jeremy

2017-10-01

A measured neutron time-of-flight (nTOF) signal is a convolution of the neutron reaction history and the instrument response function (IRF). For this work, the IRF was obtained by measuring single, D-T neutron events by utilizing n-alpha coincidence. The d(t, α) n nuclear reaction was produced at Sandia National Laboratories' Ion Beam Laboratory using a 300-keV Cockroft-Walton generator to accelerate a 2- μA beam, of 175-keV D + ions, into a stationary, 2.6- μm, ErT2 target. Comparison of these results to those obtained using cosmic-rays and photons will be discussed. Sandia National Laboratories.

Ion-molecule interactions in crossed-beams. [N/sup +/-H/sub 2/; F/sup +/-H; CO/sub 2//sup +/-D/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Hansen, S.G.

1980-09-01

Interactions of the ions N/sup +/, F/sup +/, and CO/sub 2//sup +/ with H/sub 2/ and/or its isotopes were examined using the crossed-beam technique in the low (< 4 eV) initial relative energy. For the reaction N/sup +/(/sup 3/P) + H/sub 2/ ..-->.. NH/sup +/ + H, complex formation dominates up to 1.9 eV and a substantial interaction occurs between all collision partners up to 3.6 eV. The distribution of N/sup +/ scattered nonreactively from H/sub 2/ also showed a long-lived complex channel below 1.9 eV. The reaction F/sup +/(/sup 3/P) + H/sub 2/ ..-->..FH/sup +/ + H proceeded by a direct reaction mechanism at 0.20 to 1.07 eV. The reaction CO/sub 2//sup +/ + D/sub 2/ ..-->.. DCO/sub 2//sup +/ + D gives asymmetric product distributions at 0.27 eV and above, indicating a direct reaction mechanism. Results indicated that there are probably barriers in the exit channels for DCO/sub 2//sup +/, DCO/sup +/, and D/sub 2/O/sup +/ products. The electronic state distributions of the N/sup +/, F/sup +/, and CO/sub 2//sup +/ beams was investigated using beam attenuation and total luminescence techniques.

Contribution to the study of low-energy (d,p) reactions on light nuclei; Contribution a l'etude des reactions (d,p) a basse energie sur noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Nguyen Van, S. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-05-15

This work is carried out with a view to analysing low energy (d,p) reactions on light nuclei measured at Grenoble or Algiers and suggesting a direct mechanism. The distorted wave approximation has been applied; this requires the development of programmes for the IBM 7044 computer at the 'Institut des Mathematiques Appliquees' in Grenoble. The (d,p) reactions on {sup 14}N, {sup 9}Be, {sup 22}Ne and {sup 16}O are dealt with. A calculation of the interference of the direct interaction and of resonating effects has been applied to {sup 16}O. (author) [French] Ce travail a pour but d'analyser les reactions (d,p) a basse energie sur noyaux legers, mesurees a Grenoble ou a Alger et qui suggerent un mecanisme direct. L'approximation des ondes distordues a ete appliquee, necessitant la mise au point de programmes sur l'ordinateur IBM 7044 de l'Institut des Mathematiques Appliquees de Grenoble. Des reactions (d,p) sur {sup 14}N, {sup 9}Be, {sup 22}Ne et {sup 16}O sont traitees. Un calcul de l'interference de l'interaction directe et des effets resonnants a ete applique a {sup 16}O. (auteur)

Disproportionation and thermochemical sulfate reduction reactions in S-H20-Ch4 and S-D2O-CH4 systems from 200 to 340 °C at elevated pressures

Science.gov (United States)

Yuan, Shunda; Chou, I-Ming; Burruss, Robert A.

2013-01-01

Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules (FSCC). After a heating period ranging from 24 to 2160 hours (hrs), the quenched samples were analyzed by Raman spectroscopy. Combined with the in situ Raman spectra collected at high temperatures and pressures in the S-H2O and S-H2O-CH4 systems, our results showed that (1) the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 °C and produced H2S, SO42-, and possibly trace amount of HSO4-; (2) sulfate (and bisulfate), in the presence of sulfur, can be reduced by methane between 250 and 340 °C to produce CO2 and H2S, and these TSR temperatures are much closer to those of the natural system (2O-CH4 system may take place simultaneously, with TSR being favored at higher temperatures; and (4) in the system S-D2O-CH4, both TSR and the competitive disproportionation reactions occurred simultaneously at temperatures above 300 °C, but these reactions were very slow at lower temperatures. Our observation of methane reaction at 250 °C in a laboratory time scale suggests that, in a geologic time scale, methane may be destroyed by TSR reactions at temperatures > 200 °C that can be reached by deep drilling for hydrocarbon resources.

1D AND 2D NMR STUDIES OF BENZYL O–VANILLIN

Directory of Open Access Journals (Sweden)

Mohammed Hadi Al–Douh

2010-06-01

Full Text Available The reaction of o-vanillin A with benzyl bromide B2 in acetone as the solvent and K2CO3 as a base in the presence of tetra-n-butylammonium iodide (TBAI as catalyst formed benzyl o-vanillin, C. The complete assignments of C using PROTON, APT, DEPT-135, COSY, NOESY, HMQC and HMBC NMR in both CDCl3 and acetone-d6 are discussed, and the coupling constants J are reported in Hertz (Hz.     Keywords: 1H NMR; 13C NMR; 2D NMR; Benzyl o-Vanillin

Kinetics of transuranium element oxidation-reduction reactions in solution; Cinetique des reactions d'oxydo-reduction des elements transuraniens en solution

Energy Technology Data Exchange (ETDEWEB)

Gourisse, D. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1966-09-01

A review of the kinetics of U, Np, Pu, Am oxidation-reduction reactions is proposed. The relations between the different activation thermodynamic functions (compensatory effect, formal entropy of the activated complex, magnitude of reactions velocities) are considered. The effects of acidity, ionic strength deuterium and mixed solvents polarity on reactions rates are described. The effect of different anions on reactions rates are explained by variations of the reaction standard free energy and variations of the activation free energy (coulombic interactions) resulting from the complexation of dissolved species by these anions. (author) [French] Une revue systematique de la cinetique des reactions d'oxydo-reduction des elements U, Np, Pu, Am, en solution perchlorique est proposee. Des considerations relatives aux grandeurs thermodynamiques d'activation associees aux actes elementaires (effet de compensation, entropie standard des complexes actives, rapidite des reactions) sont developpees. L'influence de l'acidite, de la force ionique, de l'eau lourde et de la polarite des solvants mixtes sur la vitesse des reactions est decrite. Enfin l'influence des differents anions sur la vitesse des reactions est expliquee par les variations de l'enthalpie libre standard de la reaction et de l'enthalpie libre d'activation (travail des forces electrostatiques) resultant de la complexation des especes dissoutes dans la solution. (auteur)

Micellar induced regioselectivity in the two-step consecutive reaction of SO3(2-) with Br-(CH2CH2)n-Br (n=2-5).

Science.gov (United States)

Currie, Fredrik; Jarvoll, Patrik; Holmberg, Krister; Romsted, Laurence S; Gunaseelan, Krishnan

2007-08-15

High field (800 MHz) (1)H NMR was used to monitor the two-step consecutive reaction of excess SO(3)(2-) with symmetrical bifunctional alpha,omega-dibromoalkanes with butane (DBB), hexane (DBH), octane (DBO), and decane (DBD) chains in CTAB micelles at 25 degrees C. The first-order rate constant for the first substitution step for DBB and DBH is about 5 times faster than for the second, but the kinetics for DBO and DBD were not cleanly first-order. After 40 min, the solution contained about 80% of the intermediate bromoalkanesulfonate from DBB and DBH and the remainder is alkanedisulfonate and unreacted starting material. The same reactions were carried out in homogeneous MeOH/D(2)O solutions at 50 degrees C. The rate constants for all four alpha,omega-dibromoalkanes were first-order throughout the time course of the reaction and the same within +/-10%. However, because micellar solutions are organized on the nanoscale and bring together lipophilic and hydrophilic reactants into a small reaction volume at the micellar interface, they speed this substitution reaction considerably compared to reaction in MeOH/D(2)O. The CTAB micelles also induce a significant regioselectivity in product formation by speeding the first step of the consecutive reaction more than the second. The results are consistent with the bromoalkanesulfonate intermediates having a radial orientation within the micelles with the -CH(2)SO(3)(-) group in the interfacial region and the -CH(2)Br group directed into the micellar core such that the concentration of -CH(2)Br groups in the reactive zone, i.e., the micellar interface, is significantly reduced. These results provide the first example of self-assembled surfactant system altering the relative rates of the reaction steps of a consecutive reaction and, in doing so, enhancing monosubstitution of a symmetrically disubstituted species.

Accurate Quantum Wave Packet Study of the Deep Well D+ + HD Reaction: Product Ro-vibrational State-Resolved Integral and Differential Cross Sections.

Science.gov (United States)

He, Haixiang; Zhu, Weimin; Su, Wenli; Dong, Lihui; Li, Bin

2018-03-08

The H + + H 2 reaction and its isotopic variants as the simplest triatomic ion-molecule reactive system have been attracting much interests, however there are few studies on the titled reaction at state-to-state level until recent years. In this work, accurate state-to-state quantum dynamics studies of the titled reaction have been carried out by a reactant Jacobi coordinate-based time-dependent wave packet approach on diabatic potential energy surfaces constructed by Kamisaka et al. Product ro-vibrational state-resolved information has been calculated for collision energies up to 0.2 eV with maximal total angular momentum J = 40. The necessity of including all K-component for accounting the Coriolis coupling for the reaction has been illuminated. Competitions between the two product channels, (D + + HD' → D' + + HD and D + + HD' → H + + DD') were investigated. Total integral cross sections suggest that resonances enhance the reactivity of channel D + + HD'→ H + + DD', however, resonances depress the reactivity of the another channel D + + HD' → D' + + HD. The structures of the differential cross sections are complicated and depend strongly on collision energies of the two channels and also on the product rotational states. All of the product ro-vibrational state-resolved differential cross sections for this reaction do not exhibit rigorous backward-forward symmetry which may indicate that the lifetimes of the intermediate resonance complexes should not be that long. The dynamical observables of this deuterated isotopic reaction are quite different from the reaction of H + + H 2 → H 2 + H + reported previously.

Verification experiment of EPR paradox by (d, {sup 2}He) reaction

Energy Technology Data Exchange (ETDEWEB)

Sakai, Hideyuki [Tokyo Univ., Graudate School of Science, Tokyo (Japan)

2003-01-01

FBR paradox which was brought forward by Einstein, Podolsky and Rosen is expressed by Bell's inequality of spin correlation theoretically. In principle it is possible to verify the inequality by measuring spin correlation between two particles having spin 1/2 from a decay of {sup 1}S{sub 0} experimentally. Most of the past experiments to verify the inequality, however, have been performed by using photons. On the other hand, only one experiment by using hadron system was carried out by Lamehi and Mitting, where the [{sup 1}S{sub 0}] state was produced by proton-proton scattering at first, and then the spin orientations after the scattering were measured. Unfortunately, there exit some sources of ambiguity to reach definite conclusion from their result because the experiment was done at rather high energy of 13.5 MeV. In the experiment planned by the present author it is designed to overcome the experimental difficulties, which Lamehi and Mitting encountered, by (1) generating high purity singlet [{sup 1}S{sub 0}] state of two protons by (d, {sup 2}He) type nuclear reaction at intermediate energy range, and by (2) developing high performance spin-correlation polarimeter which can analyze spins of two protons simultaneously to minimize the systematic errors. The excitation energy of {sup 2}He corresponding to the proton-proton relative energy can be experimentally controlled. An idea singlet is realized by choosing the state with sufficiently small relative energy. It is planned to measure the spin correlation function by using SMART (Swinger and Magnetic Analyzer with Rotator and Twister) at RIKEN Accelerator Research Facility. Einstein POLarimeter (EPOL) to be installed on the second focal plane of SMART is under development, with which high precision measurements of spin orientations of two high energy protons simultaneously coming into limited space from {sup 2}He decay are made selecting the subject events from very many background events. Monte Carlo

Gold-Catalyzed Formal C-C Bond Insertion Reaction of 2-Aryl-2-diazoesters with 1,3-Diketones.

Science.gov (United States)

Ren, Yuan-Yuan; Chen, Mo; Li, Ke; Zhu, Shou-Fei

2018-06-29

The transition-metal-catalyzed formal C-C bond insertion reaction of diazo compounds with monocarbonyl compounds is well established, but the related reaction of 1,3-diketones instead gives C-H bond insertion products. Herein, we report a protocol for a gold-catalyzed formal C-C bond insertion reaction of 2-aryl-2-diazoesters with 1,3-diketones, which provides efficient access to polycarbonyl compounds with an all-carbon quaternary center. The aryl ester moiety plays a crucial role in the unusual chemoselectivity, and the addition of a Brønsted acid to the reaction mixture improves the yield of the C-C bond insertion product. A reaction mechanism involving cyclopropanation of a gold carbenoid with an enolate and ring-opening of the resulting donor-acceptor-type cyclopropane intermediate is proposed. This mechanism differs from that of the traditional Lewis-acid-catalyzed C-C bond insertion reaction of diazo compounds with monocarbonyl compounds, which involves a rearrangement of a zwitterion intermediate as a key step. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Report compiled by Research Center for Carbonaceous Resources, Institute for Chemical Reaction Science, Tohoku University; Tohoku Daigaku Hanno Kagaku Kenkyusho tanso shigen hanno kenkyu center hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-04-01

The Research Center for Carbonaceous Resources was established in April 1991 for the purpose of developing a comprehensive process for converting carbonaceous resources into clean fuels or into materials equipped with advanced functions. In this report, the track records etc. of the center are introduced. Under study in the conversion process research department is the organization of a comprehensive coal conversion process which will be a combination of solvent extraction, catalytic decomposition, and catalytic gasification, whose goal is to convert coal in a clean way at high efficiency. Under study in the conversion catalyst research department are the development of a coal denitrogenation method, development of a low-temperature gasification method by use of inexpensive catalysts, synthesis of C{sub 2} hydrocarbons in a methane/carbon dioxide reaction, etc. Other endeavors under way involve the designing and development of new organic materials such as new carbon materials and a study of the foundation on which such efforts stand, that is, the study of the control of reactions between solids. Furthermore, in the study of interfacial reaction control, the contact gasification of coal, brown coal ion exchange capacity and surface conditions, carbonization of cation exchanged brown coal, etc., are being developed. (NEDO)

Phosphorescent and thermoluminescent properties of SrAl2O4:Eu2+, Dy3+ phosphors prepared by solid state reaction method

International Nuclear Information System (INIS)

Mothudi, B.M.; Ntwaeaborwa, O.M.; Kumar, A.; Sohn, K.; Swart, H.C.

2012-01-01

Long persistent SrAl 2 O 4 :Eu 2+ phosphors co-doped with Dy 3+ were prepared by the solid state reaction method. The main diffraction peaks of the monoclinic structure of SrAl 2 O 4 were observed in all the samples. The broad band emission spectra at 497 nm for SrAl 2 O 4 :Eu 2+ , Dy 3+ were observed and the emission is attributed to the 4f 6 5d 1 to 4f 7 transition of Eu 2+ ions. The samples annealed at 1100–1200 °C showed similar broad TL glow curves centered at 120 °C. The similar TL glow curves suggest that the traps responsible for them are similar. The long afterglow displayed by the phosphors annealed at different temperatures, may be attributed to the Dy 3+ ions acting as the hole trap levels, which play an important role in prolonging the duration of luminescence.

Bacterial Reaction Centers Purified with Styrene Maleic Acid Copolymer Retain Native Membrane Functional Properties and Display Enhanced Stability**

Science.gov (United States)

Swainsbury, David J K; Scheidelaar, Stefan; van Grondelle, Rienk; Killian, J Antoinette; Jones, Michael R

2014-01-01

Integral membrane proteins often present daunting challenges for biophysical characterization, a fundamental issue being how to select a surfactant that will optimally preserve the individual structure and functional properties of a given membrane protein. Bacterial reaction centers offer a rare opportunity to compare the properties of an integral membrane protein in different artificial lipid/surfactant environments with those in the native bilayer. Here, we demonstrate that reaction centers purified using a styrene maleic acid copolymer remain associated with a complement of native lipids and do not display the modified functional properties that typically result from detergent solubilization. Direct comparisons show that reaction centers are more stable in this copolymer/lipid environment than in a detergent micelle or even in the native membrane, suggesting a promising new route to exploitation of such photovoltaic integral membrane proteins in device applications. PMID:25212490

Simulations. 3D nuclear reactions; Simulations. Reactions nucleaires en 3D

Energy Technology Data Exchange (ETDEWEB)

Deleurence, Guillaume

2012-05-15

At CEA Saclay, the research programme for the forth generation of nuclear reactors, named 'Astrid' (Advanced Sodium Technological Reactor for Industrial Demonstration) of the Direction of nuclear energy (DEN), uses 2D or 3D movies and a 16 m{sup 2} image wall for the display of simulation results. This digest paper focusses on the technological means used for the simulations: the Curie supercomputer designed by Bull and the images display device. (J.S.)

Homogeneous catalysis of deuterium transfer by potassium hydroxide and potassium methoxide D2-H2O and D2-CH3OH exchange

International Nuclear Information System (INIS)

Strathdee, G.G.; Garner, D.M.; Given, R.M.

1977-01-01

The kinetics and mechanism of exchange of deuterium between D 2 and water and between D 2 and methanol, catalyzed respectively by concentrated potassium hydroxide and potassium methoxide, has been studied between 348 and 398 K. In the D 2 -KOH-H 2 O case, the transfer of deuterium was found to be controlled by the rate of activation of the D 2 molecule by OH - . Rapid exchange of D + with the aqueous solution followed. From the D 2 -KOCH 3 -CH 3 OH studies, it was concluded that deuterium exchange depended upon the rates of both D 2 activation by methoxide and interaction of the solvent with the transition, or encounter, complex. The dependence of second-order rate constants on solvent activity for both systems was determined by normalization of the exchange reaction rates to unit reagent activity. Analysis of the kinetic isotope effects for each system suggested that their increase with base concentration or temperature was due to solvation effects. (author)

Spectral properties of chlorines and electron transfer with their participation in the photosynthetic reaction center of photosystem II

Science.gov (United States)

Shchupak, E. E.; Ivashin, N. V.

2014-02-01

Structural factors that provide localization of excited states and determine the properties of primary donor and acceptor of electron in the reaction center of photosystem II (PSII RC) are studied. The results of calculations using stationary and time-dependent density functional theory indicate an important role of protein environments of chlorophylls PA, PB, BA, and BB and pheophytins HA and HB in the area with a radius of no greater than ≤10 Å in the formation of excitonic states of PSII RC. When the neighboring elements are taken into account, the wavelength of long-wavelength Q y transition of chlorophyll molecules is varied by about 10 nm. The effect is less developed for pheophytin molecules (Δλ ≅ 2 nm). The following elements strongly affect energy of the transition: HisA198 and HisD197 amino-acid residues that serve as ligands of magnesium atoms affect PA and PB, respectively; MetA183 affects PA; MetA172 and MetD198 affect BA; water molecules that are located above the planes of the BA and BB macrocycles form H bonds with carbonyl groups; and phytol chains of PA and PB affect BA, BB, HA, and HB. The analysis of excitonic states, mutual positions of molecular orbitals of electron donors and acceptors, and matrix elements of electron transfer reaction shows that (i) charge separation between BA and HA and PB and BA is possible in the active A branch of cofactors of PSII RC and (ii) electron transfer is blocked at the BB - HB fragment in inactive B branch of PSII RC.

The quasi-free reaction p+d → d+η+p{sub sp} at ANKE

Energy Technology Data Exchange (ETDEWEB)

Schroeer, Daniel; Fritzsch, Christopher; Khoukaz, Alfons; Rump, Marcel [Institut fuer Kernphysik, Westfaelische Wilhelms-Universitaet, Muenster (Germany); Collaboration: ANKE-Collaboration

2016-07-01

The interaction between η mesons and hadrons is an intensively investigated topic. Due to its stength it might lead to the formation of η-mesic nuclei. In order to study the characteristics of this interaction a measurement of the reaction p+d → d+η+p{sub sp} has been performed at the ANKE spectrometer at the COSY accelerator of the Forschungszentrum Juelich. In this context the deuteron serves as an effective neutron target whereas the proton is treated as a spectator particle. The two different beam momenta (p{sub 1} = 2.09 GeV/c and p{sub 2} = 2.25 GeV/c) in combination with the Fermi motion inside the target deuteron grant access to the determination of total and differential cross sections in an excess energy range from threshold up to Q = 90 MeV. While the course of the total cross section, especially near threshold, will allow to compute the scattering length a{sub dη} of an s-wave final state interaction ansatz, the differential cross sections permit to verify the legitimacy of the s-wave assumption. Furthermore the data taken at higher excess energies enable to examine the role of nucleonic resonances in the production process of η mesons. Recent results are presented and discussed.

Spectroscopic Factors from the Single Neutron Transfer Reaction 111Cd(d,p)112Cd

Science.gov (United States)

Jamieson, D. S.; Garrett, P. E.; Demand, G. A.; Finlay, P.; Green, K. L.; Leach, K. G.; Phillips, A. A.; Svensson, C. E.; Sumithrarachchi, C. S.; Triambak, S.; Wong, J.; Ball, G.; Faestermann, T.; Krücken, R.; Hertenberger, R.; Wirth, H.-F.

2013-03-01

The cadmium isotopes have been cited as excellent examples of vibrational nuclei for decades, with multi-phonon quadrupole, quadrupole-octupole, and mixed-symmetry states proposed. From a variety of experimental studies, a large amount of spectroscopic data has been obtained, recently focused on γ-ray studies. In the present work, the single-particle structure of 112Cd has been investigated using the 111Cd(ěcd, p)112Cd reaction. The investigation was carried out using a 22 MeV beam of polarized deuterons obtained from the Maier-Leibnitz Laboratory at Garching, Germany. The reaction ejectiles were momentum analyzed using a Q3D spectrograph, and 115 levels have been identified up to 4.2 MeV of excitation energy. Spin-parity has been assigned to each analyzed level, and angular distributions for the reaction cross sections and analyzing powers were obtained. Many additional levels have been observed compared with the previous (d,p) study performed with 8 MeV deuterons,1 including strongly populated 5- and 6- states. The former was previously assigned as a member of the quadrupole-octupole quintuplet, based on a strongly enhanced B(E2) value to the 3- state, but is now re-assigned as being predominately s1/2 ⊗ h11/2 configuration.

Bioconversion of D-galactose to D-tagatose: continuous packed bed reaction with an immobilized thermostable L-arabinose isomerase and efficient purification by selective microbial degradation.

Science.gov (United States)

Liang, Min; Chen, Min; Liu, Xinying; Zhai, Yafei; Liu, Xian-wei; Zhang, Houcheng; Xiao, Min; Wang, Peng

2012-02-01

The continuous enzymatic conversion of D-galactose to D-tagatose with an immobilized thermostable L-arabinose isomerase in packed-bed reactor and a novel method for D-tagatose purification were studied. L-arabinose isomerase from Thermoanaerobacter mathranii (TMAI) was recombinantly overexpressed and immobilized in calcium alginate. The effects of pH and temperature on D-tagatose production reaction catalyzed by free and immobilized TMAI were investigated. The optimal condition for free enzyme was pH 8.0, 60°C, 5 mM MnCl(2). However, that for immobilized enzyme was pH 7.5, 75°C, 5 mM MnCl(2). In addition, the catalytic activity of immobilized enzyme at high temperature and low pH was significantly improved compared with free enzyme. The optimum reaction yield with immobilized TMAI increased by four percentage points to 43.9% compared with that of free TMAI. The highest productivity of 10 g/L h was achieved with the yield of 23.3%. Continuous production was performed at 70°C; after 168 h, the reaction yield was still above 30%. The resultant syrup was then incubated with Saccharomyces cerevisiae L1 cells. The selective degradation of D-galactose was achieved, obtaining D-tagatose with the purity above 95%. The established production and separation methods further potentiate the industrial production of D-tagatose via bioconversion and biopurification processes.

Charge symmetry breaking in the reaction np→dπ0

International Nuclear Information System (INIS)

Niskanen, J.A.; Sebestyen, M.; Thomas, A.W.

1988-01-01

By extending a coupled channels model which has proven successful in describing the reaction pp→π + d, we make predictions for charge symmetry breaking effects in the reaction np→dπ 0 . We find that nucleon and delta mass differences at vertices where pions are emitted or absorbed are important (as for np elastic scattering). However, eta-π 0 mixing is also important in pion production. We predict forward-backward asymmetries in the pion production differential cross section as large as 1% (for laboratory energies below 800 MeV). The asymmetries induced in polarization observables are small

Design Application Translates 2-D Graphics to 3-D Surfaces

Science.gov (United States)

2007-01-01

Fabric Images Inc., specializing in the printing and manufacturing of fabric tension architecture for the retail, museum, and exhibit/tradeshow communities, designed software to translate 2-D graphics for 3-D surfaces prior to print production. Fabric Images' fabric-flattening design process models a 3-D surface based on computer-aided design (CAD) specifications. The surface geometry of the model is used to form a 2-D template, similar to a flattening process developed by NASA's Glenn Research Center. This template or pattern is then applied in the development of a 2-D graphic layout. Benefits of this process include 11.5 percent time savings per project, less material wasted, and the ability to improve upon graphic techniques and offer new design services. Partners include Exhibitgroup/Giltspur (end-user client: TAC Air, a division of Truman Arnold Companies Inc.), Jack Morton Worldwide (end-user client: Nickelodeon), as well as 3D Exhibits Inc., and MG Design Associates Corp.