Direct dynamics simulations of the unimolecular dissociation of dioxetane: Probing the non-RRKM dynamics

NASA Astrophysics Data System (ADS)

Malpathak, Shreyas; Ma, Xinyou; Hase, William L.

2018-04-01

In a previous UB3LYP/6-31G* direct dynamics simulation, non-Rice-Ramsperger-Kassel-Marcus (RRKM) unimolecular dynamics was found for vibrationally excited 1,2-dioxetane (DO); [R. Sun et al., J. Chem. Phys. 137, 044305 (2012)]. In the work reported here, these dynamics are studied in more detail using the same direct dynamics method. Vibrational modes of DO were divided into 4 groups, based on their characteristic motions, and each group excited with the same energy. To compare with the dynamics of these groups, an additional group of trajectories comprising a microcanonical ensemble was also simulated. The results of these simulations are consistent with the previous study. The dissociation probability, N(t)/N(0), for these excitation groups were all different. Groups A, B, and C, without initial excitation in the O-O stretch reaction coordinate, had a time lag to of 0.25-1.0 ps for the first dissociation to occur. Somewhat surprisingly, the C-H stretch Group A and out-of-plane motion Group C excitations had exponential dissociation probabilities after to, with a rate constant ˜2 times smaller than the anharmonic RRKM value. Groups B and D, with excitation of the H-C-H bend and wag, and ring bend and stretch modes, respectively, had bi-exponential dissociation probabilities. For Group D, with excitation localized in the reaction coordinate, the initial rate constant is ˜7 times larger than the anharmonic RRKM value, substantial apparent non-RRKM dynamics. N(t)/N(0) for the random excitation trajectories was non-exponential, indicating intrinsic non-RRKM dynamics. For the trajectory integration time of 13.5 ps, 9% of these trajectories did not dissociate in comparison to the RRKM prediction of 0.3%. Classical power spectra for these trajectories indicate they have regular intramolecular dynamics. The N(t)/N(0) for the excitation groups are well described by a two-state coupled phase space model. From the intercept of N(t)/N(0) with random excitation, the anharmonic correction to the RRKM rate constant is approximately a factor of 1.5.

Quantum dynamics of the intramolecular vibrational energy redistribution in OCS: From localization to quasi-thermalization

NASA Astrophysics Data System (ADS)

Pérez, J. B.; Arce, J. C.

2018-06-01

We report a fully quantum-dynamical study of the intramolecular vibrational energy redistribution (IVR) in the electronic ground state of carbonyl sulfide, which is a prototype of an isolated many-body quantum system with strong internal couplings and non-Rice-Ramsperger-Kassel-Marcus (RRKM) behavior. We pay particular attention to the role of many-body localization and the approach to thermalization, which currently are topics of considerable interest, as they pertain to the very foundations of statistical mechanics and thermodynamics. We employ local-mode (valence) coordinates and consider initial excitations localized in one local mode, with energies ranging from low to near the dissociation threshold, where the classical dynamics have been shown to be chaotic. We propagate the nuclear wavepacket on the potential energy surface by means of the numerically exact multiconfiguration time-dependent Hartree method and employ mean local energies, time-dependent and time-averaged populations in quantum number space, energy distributions, entanglement entropies, local population distributions, microcanonical averages, and dissociation probabilities, as diagnostic tools. This allows us to identify a continuous localization → delocalization transition in the energy flow, associated with the onset of quantum chaos, as the excitation energy increases up to near the dissociation threshold. Moreover, we find that at this energy and ˜1 ps the molecule nearly thermalizes. Furthermore, we observe that IVR is so slow that the molecule begins to dissociate well before such quasi-thermalization is complete, in accordance with earlier classical-mechanical predictions of non-RRKM behavior.

Quantum dynamics of the intramolecular vibrational energy redistribution in OCS: From localization to quasi-thermalization.

PubMed

Pérez, J B; Arce, J C

2018-06-07

We report a fully quantum-dynamical study of the intramolecular vibrational energy redistribution (IVR) in the electronic ground state of carbonyl sulfide, which is a prototype of an isolated many-body quantum system with strong internal couplings and non-Rice-Ramsperger-Kassel-Marcus (RRKM) behavior. We pay particular attention to the role of many-body localization and the approach to thermalization, which currently are topics of considerable interest, as they pertain to the very foundations of statistical mechanics and thermodynamics. We employ local-mode (valence) coordinates and consider initial excitations localized in one local mode, with energies ranging from low to near the dissociation threshold, where the classical dynamics have been shown to be chaotic. We propagate the nuclear wavepacket on the potential energy surface by means of the numerically exact multiconfiguration time-dependent Hartree method and employ mean local energies, time-dependent and time-averaged populations in quantum number space, energy distributions, entanglement entropies, local population distributions, microcanonical averages, and dissociation probabilities, as diagnostic tools. This allows us to identify a continuous localization → delocalization transition in the energy flow, associated with the onset of quantum chaos, as the excitation energy increases up to near the dissociation threshold. Moreover, we find that at this energy and ∼1 ps the molecule nearly thermalizes. Furthermore, we observe that IVR is so slow that the molecule begins to dissociate well before such quasi-thermalization is complete, in accordance with earlier classical-mechanical predictions of non-RRKM behavior.

Barrierless association of CF2 and dissociation of C2F4 by variational transition-state theory and system-specific quantum Rice-Ramsperger-Kassel theory.

PubMed

Bao, Junwei Lucas; Zhang, Xin; Truhlar, Donald G

2016-11-29

Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C 2 F 4 ), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice-Ramsperger-Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements.

Tunneling effects in the unimolecular decay of (CH 3) 2COO Criegee intermediates to OH radical products

DOE PAGES

Fang, Yi; Barber, Victoria P.; Klippenstein, Stephen J.; ...

2017-04-04

Unimolecular decay of the dimethyl substituted Criegee intermediate (CH 3) 2COO is observed at energies significantly below the transition state barrier associated with hydrogen atom transfer with time-resolved detection of the resultant OH radical products. (CH 3) 2COO is prepared at specific energies in the 3900-4600 cm -1 region through IR excitation of combination bands involving CH stretch and another lower frequency mode, and the OH products are detected by UV laser-induced fluorescence. OH appearance times on the order of microseconds are observed in this deep tunneling regime, which are about 100 times slower than that in the vicinity ofmore » the barrier. The experimental rates are in good accord with Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of the microcanonical dissociation rates for (CH 3) 2COO that include tunneling. Master equation modeling based on these microcanonical rates is used to predict the thermal decay rate of (CH 3) 2COO to OH products under atmospheric conditions of 276 s -1 at 298 K (high pressure limit). Furthermore, thermal unimolecular decay of (CH 3) 2COO to OH products is shown to have significant contributions from tunneling at energies much below the barrier to H-atom transfer.« less

Tunneling effects in the unimolecular decay of (CH 3) 2COO Criegee intermediates to OH radical products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Yi; Barber, Victoria P.; Klippenstein, Stephen J.

Unimolecular decay of the dimethyl substituted Criegee intermediate (CH 3) 2COO is observed at energies significantly below the transition state barrier associated with hydrogen atom transfer with time-resolved detection of the resultant OH radical products. (CH 3) 2COO is prepared at specific energies in the 3900-4600 cm -1 region through IR excitation of combination bands involving CH stretch and another lower frequency mode, and the OH products are detected by UV laser-induced fluorescence. OH appearance times on the order of microseconds are observed in this deep tunneling regime, which are about 100 times slower than that in the vicinity ofmore » the barrier. The experimental rates are in good accord with Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of the microcanonical dissociation rates for (CH 3) 2COO that include tunneling. Master equation modeling based on these microcanonical rates is used to predict the thermal decay rate of (CH 3) 2COO to OH products under atmospheric conditions of 276 s -1 at 298 K (high pressure limit). Furthermore, thermal unimolecular decay of (CH 3) 2COO to OH products is shown to have significant contributions from tunneling at energies much below the barrier to H-atom transfer.« less

Kinetics of Thermal Unimolecular Decomposition of Acetic Anhydride: An Integrated Deterministic and Stochastic Model.

PubMed

Mai, Tam V-T; Duong, Minh V; Nguyen, Hieu T; Lin, Kuang C; Huynh, Lam K

2017-04-27

An integrated deterministic and stochastic model within the master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) framework was first used to characterize temperature- and pressure-dependent behaviors of thermal decomposition of acetic anhydride in a wide range of conditions (i.e., 300-1500 K and 0.001-100 atm). Particularly, using potential energy surface and molecular properties obtained from high-level electronic structure calculations at CCSD(T)/CBS, macroscopic thermodynamic properties and rate coefficients of the title reaction were derived with corrections for hindered internal rotation and tunneling treatments. Being in excellent agreement with the scattered experimental data, the results from deterministic and stochastic frameworks confirmed and complemented each other to reveal that the main decomposition pathway proceeds via a 6-membered-ring transition state with the 0 K barrier of 35.2 kcal·mol -1 . This observation was further understood and confirmed by the sensitivity analysis on the time-resolved species profiles and the derived rate coefficients with respect to the ab initio barriers. Such an agreement suggests the integrated model can be confidently used for a wide range of conditions as a powerful postfacto and predictive tool in detailed chemical kinetic modeling and simulation for the title reaction and thus can be extended to complex chemical reactions.

How to Compute Electron Ionization Mass Spectra from First Principles.

PubMed

Bauer, Christoph Alexander; Grimme, Stefan

2016-06-02

The prediction of electron ionization (EI) mass spectra (MS) from first principles has been a major challenge for quantum chemistry (QC). The unimolecular reaction space grows rapidly with increasing molecular size. On the one hand, statistical models like Eyring's quasi-equilibrium theory and Rice-Ramsperger-Kassel-Marcus theory have provided valuable insight, and some predictions and quantitative results can be obtained from such calculations. On the other hand, molecular dynamics-based methods are able to explore automatically the energetically available regions of phase space and thus yield reaction paths in an unbiased way. We describe in this feature article the status of both methodologies in relation to mass spectrometry for small to medium sized molecules. We further present results obtained with the QCEIMS program developed in our laboratory. Our method, which incorporates stochastic and dynamic elements, has been a significant step toward the reliable routine calculation of EI mass spectra.

Isomerization reaction dynamics and equilibrium at the liquid-vapor interface of water. A molecular-dynamics study

NASA Technical Reports Server (NTRS)

Benjamin, Ilan; Pohorille, Andrew

1993-01-01

The gauche-trans isomerization reaction of 1,2-dichloroethane at the liquid-vapor interface of water is studied using molecular-dynamics computer simulations. The solvent bulk and surface effects on the torsional potential of mean force and on barrier recrossing dynamics are computed. The isomerization reaction involves a large change in the electric dipole moment, and as a result the trans/gauche ratio is considerably affected by the transition from the bulk solvent to the surface. Reactive flux correlation function calculations of the reaction rate reveal that deviation from the transition-state theory due to barrier recrossing is greater at the surface than in the bulk water. This suggests that the system exhibits non-Rice-Ramsperger-Kassel-Marcus behavior due to the weak solvent-solute coupling at the water liquid-vapor interface.

New insights into thermal decomposition of polycyclic aromatic hydrocarbon oxyradicals.

PubMed

Liu, Peng; Lin, He; Yang, Yang; Shao, Can; Gu, Chen; Huang, Zhen

2014-12-04

Thermal decompositions of polycyclic aromatic hydrocarbon (PAH) oxyradicals on various surface sites including five-membered ring, free-edge, zigzag, and armchair have been systematically investigated by using ab initio density functional theory B3LYP/6-311+G(d,p) basis set. The calculation based on Hückel theory indicates that PAHs (3H-cydopenta[a]anthracene oxyradical) with oxyradicals on a five-membered ring site have high chemical reactivity. The rate coefficients of PAH oxyradical decomposition were evaluated by using Rice-Ramsperger-Kassel-Marcus theory and solving the master equations in the temperature range of 1500-2500 K and the pressure range of 0.1-10 atm. The kinetic calculations revealed that the rate coefficients of PAH oxyradical decomposition are temperature-, pressure-, and surface site-dependent, and the oxyradical on a five-membered ring is easier to decompose than that on a six-membered ring. Four-membered rings were found in decomposition of the five-membered ring, and a new reaction channel of PAH evolution involving four-membered rings is recommended.

Pressure-dependent kinetics of initial reactions in iso-octane pyrolysis.

PubMed

Ning, HongBo; Gong, ChunMing; Li, ZeRong; Li, XiangYuan

2015-05-07

This study focuses on the studies of the main pressure-dependent reaction types of iso-octane (iso-C8H18) pyrolysis, including initial C-C bond fission of iso-octane, isomerization, and β-scission reactions of the alkyl radicals produced by the C-C bond fission of iso-octane. For the C-C bond fission of iso-octane, the minimum energy potentials are calculated at the CASPT2(2e,2o)/6-31+G(d,p)//CAS(2e,2o)/6-31+G(d,p) level of theory. For the isomerization and the β-scission reactions of the alkyl radicals, the optimization of the geometries and the vibrational frequencies of the reactants, transition states, and products are performed at the B3LYP/CBSB7 level, and their single point energies are calculated by using the composite CBS-QB3 method. Variable reaction coordinate transition state theory (VRC-TST) is used for the high-pressure limit rate constant calculation and Rice-Ramsperger-Kassel-Marcus/master equation (RRKM/ME) is used to calculate the pressure-dependent rate constants of these channels with pressure varying from 0.01-100 atm. The rate constants obtained in this work are in good agreement with those available from literatures. We have updated the rate constants and thermodynamic parameters for species involved in these reactions into a current chemical kinetic mechanism and also have improved the concentration profiles of main products such as C3H6 and C4H6 in the shock tube pyrolysis of iso-octane. The results of this study provide insight into the pyrolysis of iso-octane and will be helpful in the future development of branched paraffin kinetic mechanisms.

Density functional theory and RRKM calculations of decompositions of the metastable E-2,4-pentadienal molecular ions.

PubMed

Solano Espinoza, Eduardo A; Vallejo Narváez, Wilmer E

2010-07-01

The potential energy profiles for the fragmentations that lead to [C(5)H(5)O](+) and [C(4)H(6)](+*) ions from the molecular ions [C(5)H(6)O](+*) of E-2,4-pentadienal were obtained from calculations at the UB3LYP/6-311G + + (3df,3pd)//UB3LYP/6-31G(d,p) level of theory. Kinetic barriers and harmonic frequencies obtained by the density functional method were then employed in Rice-Ramsperger-Kassel-Marcus calculations of individual rate coefficients for a large number of reaction steps. The pre-equilibrium and rate-controlling step approximations were applied to different regions of the complex potential energy surface, allowing the overall rate of decomposition to be calculated and discriminated between three rival pathways: C-H bond cleavage, decarbonylation and cyclization. These processes should have to compete for an equilibrated mixture of four conformers of the E-2,4-pentadienal ions. The direct dissociation, however, can only become important in the high-energy regime. In contrast, loss of CO and cyclization are observable processes in the metastable kinetic window. The former involves a slow 1,2-hydrogen shift from the carbonyl group that is immediately followed by the formation of an ion-neutral complex which, in turn, decomposes rapidly to the s-trans-1,3-butadiene ion [C(4)H(6)](+*). The predominating metastable channel is the second one, that is, a multi-step ring closure which starts with a rate-limiting cis-trans isomerization. This process yields a mixture of interconverting pyran ions that dissociates to the pyrylium ions [C(5)H(5)O](+). These results can be used to rationalize the CID mass spectrum of E-2,4-pentadienal in a low-energy regime. 2010 John Wiley & Sons, Ltd.

Photodissociation dynamics of the 2-propyl radical, C{sub 3}H{sub 7}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noller, Bastian; Fischer, Ingo

2007-04-14

The photodissociation of 2-propyl leading to propene+H was investigated with nanosecond time resolution. A supersonic beam of isolated 2-propyl radicals was produced by pyrolysis of 2-bromopopane. The kinetic energy release of the H-atom photofragment was monitored as a function of excitation wavelength by photofragment Doppler spectroscopy via the Lyman-{alpha} transition. The loss of hydrogen atoms after excitation proceeds in {alpha} position to the radical center with a rate constant of 5.8x10{sup 7} s{sup -1} at 254 nm. Approximately 20% of the excess energy is deposited as translation in the H-atom photofragment. In contrast 1-propyl does not lose H atoms tomore » a significant extent. The experimental results are compared to simple Rice-Ramsperger-Kassel-Marcus calculations. The possible reaction pathways are examined in hybrid density functional theory calculations.« less

Mechanistic and kinetic study on the reaction of ozone and trans-2-chlorovinyldichloroarsine.

PubMed

Zhang, Wanqiao; Sun, Hao; Chen, Wei; Zhang, Yunju; Wang, Fengdi; Tang, Shuwei; Zhang, Jingping; Wang, Haitao; Wang, Rongshun

2016-05-01

Singlet and triplet potential energy surfaces for the atmospheric ozonation of trans-2-chlorovnyldichloroarsine (lewisite) are investigated theoretically. Optimizations of the reactants, products, intermediates and transition states are carried out at the BHandHLYP/6-311+G(d,p) level. Single point energy calculations are performed at the CCSD(T)/6-311+G(d,p) level based on the optimized structures. The detailed mechanism is presented and discussed. Various possible H (or Cl)-abstraction and C (or As)-addition/elimination pathways are considered. The results show that the As-addition/elimination is more energetically favorable than the other mechanisms. Rice-Ramsperger-Kassel-Marcus (RRKM) theory is used to compute the rate constants over the possible atmospheric temperature range of 200-3000 K and the pressure range of 10(-8)-10(9) Torr. The calculated rate constant is in good agreement with the available experimental data. The total rate coefficient shows positive temperature dependence and pressure independence. The modified three-parameter Arrhenius expressions for the total rate coefficient and individual rate coefficients are represented. Calculation results show that major product is CHClCHAs(OOO)Cl2 (s-IM3) at the temperature below 600 K and O2 + CHClCHAsOCl2 (s-P9) play an important role at the temperature between 600 and 3000 K. Time-dependent DFT (TD-DFT) calculations indicate that CHCl(OOO)CHAsCl2 (s-IM3) and CHOAsCl2 (s-P5) can take photolysis easily in the sunlight. Due to the absence of spectral information for arsenide, computational vibrational spectra of the important intermediates and products are also analyzed to provide valuable evidence for subsequent experimental identification. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measuring the internal energies of species emitted from hypervelocity nanoprojectile impacts on surfaces using recalibrated benzylpyridinium probe ions

NASA Astrophysics Data System (ADS)

DeBord, J. Daniel; Verkhoturov, Stanislav V.; Perez, Lisa M.; North, Simon W.; Hall, Michael B.; Schweikert, Emile A.

2013-06-01

We present herein a framework for measuring the internal energy distributions of vibrationally excited molecular ions emitted from hypervelocity nanoprojectile impacts on organic surfaces. The experimental portion of this framework is based on the measurement of lifetime distributions of "thermometer" benzylpyridinium ions dissociated within a time of flight mass spectrometer. The theoretical component comprises re-evaluation of the fragmentation energetics of benzylpyridinium ions at the coupled-cluster singles and doubles with perturbative triples level. Vibrational frequencies for the ground and transition states of select molecules are reported, allowing for a full description of vibrational excitations of these molecules via Rice-Ramsperger-Kassel-Marcus unimolecular fragmentation theory. Ultimately, this approach is used to evaluate the internal energy distributions from the measured lifetime distributions. The average internal energies of benzylpyridinium ions measured from 440 keV Au400+4 impacts are found to be relatively low (˜0.24 eV/atom) when compared with keV atomic bombardment of surfaces (1-2 eV/atom).

Variational transition state theory: theoretical framework and recent developments.

PubMed

Bao, Junwei Lucas; Truhlar, Donald G

2017-12-11

This article reviews the fundamentals of variational transition state theory (VTST), its recent theoretical development, and some modern applications. The theoretical methods reviewed here include multidimensional quantum mechanical tunneling, multistructural VTST (MS-VTST), multi-path VTST (MP-VTST), both reaction-path VTST (RP-VTST) and variable reaction coordinate VTST (VRC-VTST), system-specific quantum Rice-Ramsperger-Kassel theory (SS-QRRK) for predicting pressure-dependent rate constants, and VTST in the solid phase, liquid phase, and enzymes. We also provide some perspectives regarding the general applicability of VTST.

Kinetics and Quantitative Structure—Activity Relationship Study on the Degradation Reaction from Perfluorooctanoic Acid to Trifluoroacetic Acid

PubMed Central

Gong, Chen; Sun, Xiaomin; Zhang, Chenxi; Zhang, Xue; Niu, Junfeng

2014-01-01

Investigation of the degradation kinetics of perfluorooctanoic acid (PFOA) has been carried out to calculate rate constants of the main elementary reactions using the multichannel Rice-Ramsperger-Kassel-Marcus theory and canonical variational transition state theory with small-curvature tunneling correction over a temperature range of 200~500 K. The Arrhenius equations of rate constants of elementary reactions are fitted. The decarboxylation is role step in the degradation mechanism of PFOA. For the perfluorinated carboxylic acids from perfluorooctanoic acid to trifluoroacetic acid, the quantitative structure–activity relationship of the decarboxylation was analyzed with the genetic function approximation method and the structure–activity model was constructed. The main parameters governing rate constants of the decarboxylation reaction from the eight-carbon chain to the two-carbon chain were obtained. As the structure–activity model shows, the bond length and energy of C1–C2 (RC1–C2 and EC1–C2) are positively correlated to rate constants, while the volume (V), the energy difference between EHOMO and ELUMO (ΔE), and the net atomic charges on atom C2 (QC2) are negatively correlated. PMID:25196516

Computational Chemical Kinetics for the Reaction of Criegee Intermediate CH2OO with HNO3 and Its Catalytic Conversion to OH and HCO.

PubMed

Raghunath, P; Lee, Yuan-Pern; Lin, M C

2017-05-25

The kinetics and mechanisms for the reaction of the Criegee intermediate CH 2 OO with HNO 3 and the unimolecular decomposition of its reaction product CH 2 (O)NO 3 are important in atmospheric chemistry. The potential-energy profile of the reactions predicted with the CCSD(T)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ method shows that the initial association yields a prereaction complex that isomerizes by H migration to yield excited intermediate nitrooxymethyl hydroperoxide NO 3 CH 2 OOH* with internal energy ∼44 kcal mol -1 . A fragmentation of this excited intermediate produces CH 2 (O)NO 3 + OH with its transition state located 5.0 kcal mol -1 below that of the reactants. Further decomposition of CH 2 (O)NO 3 produces HCO + HNO 3 , forming a catalytic cycle for destruction of CH 2 OO by HNO 3 . The rate coefficients and product-branching ratios were calculated in the temperature range 250-700 K at pressure 20-760 Torr (N 2 ) using the variational-transition-state and Rice-Ramsperger-Kassel-Marcus (RRKM) theories. The predicted total rate coefficient for reaction CH 2 OO + HNO 3 at 295 K, 5.1 × 10 -10 cm 3 molecule -1 s -1 , agrees satisfactorily with the experimental value, (5.4 ± 1.0) × 10 -10 cm 3 molecule -1 s -1 . The predicted branching ratios at 295 K are 0.21 for the formation of NO 3 CH 2 OOH and 0.79 for CH 2 (O)NO 3 + OH at a pressure of 40 Torr (N 2 ), and 0.79 for the formation of NO 3 CH 2 OOH and 0.21 for CH 2 (O)NO 3 + OH at 760 Torr (N 2 ). This new catalytic conversion of CH 2 OO to HCO + OH by HNO 3 might have significant impact on atmospheric chemistry.

An ab initio/Rice-Ramsperger-Kassel-Marcus study of the hydrogen-abstraction reactions of methyl ethers, H(3)COCH(3-x)(CH(3))(x), x = 0-2, by OH; mechanism and kinetics.

PubMed

Zhou, Chong-Wen; Simmie, John M; Curran, Henry J

2010-07-14

A theoretical study of the mechanism and kinetics of the H-abstraction reaction from dimethyl (DME), ethylmethyl (EME) and iso-propylmethyl (IPME) ethers by the OH radical has been carried out using the high-level methods CCSD(T)/CBS, G3 and G3MP2BH&H. The computationally less-expensive methods of G3 and G3MP2BH&H yield results for DME within 0.2-0.6 and 0.7-0.9 kcal mol(-1), respectively, of the coupled cluster, CCSD(T), values extrapolated to the basis set limit. So the G3 and G3MP2BH&H methods can be confidently used for the reactions of the higher ethers. A distinction is made between the two different kinds of H-atoms, classified as in/out-of the symmetry plane, and it is found that abstraction from the out-of-plane H-atoms proceeds through a stepwise mechanism involving the formation of a reactant complex in the entrance channel and product complex in the exit channel. The in-plane H-atom abstractions take place through a more direct mechanism and are less competitive. Rate constants of the three reactions have been calculated in the temperature range of 500-3000 K using the Variflex code, based on the weak collision, master equation/microcanonical variational RRKM theory including tunneling corrections. The computed total rate constants (cm(3) mol(-1) s(-1)) have been fitted as follows: k(DME) = 2.74 xT(3.94) exp (1534.2/T), k(EME) = 20.93 xT(3.61) exp (2060.1/T) and k(IPME) = 0.55 xT(3.93) exp (2826.1/T). Expressions of the group rate constants for the three different carbon sites are also provided.

A Short Account of RRKM Theory of Unimolecular Reactions and of Marcus Theory of Electron Transfer in a Historical Perspective

ERIC Educational Resources Information Center

Di Giacomo, Francesco

2015-01-01

The RRKM Theory of Unimolecular Reactions and Marcus Theory of Electron Transfer are here briefly discussed in a historical perspective. In the final section, after a general discussion on the educational usefulness of teaching chemistry in a historical framework, hints are given on how some characteristics of Marcus' work could be introduced in…

Direct dynamics simulation of dioxetane formation and decomposition via the singlet .O-O-CH2-CH2. biradical: Non-RRKM dynamics

NASA Astrophysics Data System (ADS)

Sun, Rui; Park, Kyoyeon; de Jong, Wibe A.; Lischka, Hans; Windus, Theresa L.; Hase, William L.

2012-07-01

Electronic structure calculations and direct chemical dynamics simulations are used to study the formation and decomposition of dioxetane on its ground state singlet potential energy surface. The stationary points for 1O2 + C2H4, the singlet .O-O-CH2-CH2. biradical, the transition state (TS) connecting this biradical with dioxetane, and the two transition states and gauche .O-CH2-CH2-O. biradical connecting dioxetane with the formaldehyde product molecules are investigated at different levels of electronic structure theory including UB3LYP, UMP2, MRMP2, and CASSCF and a range of basis sets. The UB3LYP/6-31G* method was found to give representative energies for the reactive system and was used as a model for the simulations. UB3LYP/6-31G* direct dynamics trajectories were initiated at the TS connecting the .O-O-CH2-CH2. biradical and dioxetane by sampling the TS's vibrational energy levels, and rotational and reaction coordinate energies, with Boltzmann distributions at 300, 1000, and 1500 K. This corresponds to the transition state theory model for trajectories that pass the TS. The trajectories were directed randomly towards both the biradical and dioxetane. A small fraction of the trajectories directed towards the biradical recrossed the TS and formed dioxetane. The remainder formed 1O2 + C2H4 and of these ˜ 40% went directly from the TS to 1O2 + C2H4 without getting trapped and forming an intermediate in the .O-O-CH2-CH2. biradical potential energy minimum, a non-statistical result. The dioxetane molecules which are formed dissociate to two formaldehyde molecules with a rate constant two orders of magnitude smaller than that predicted by Rice-Ramsperger-Kassel-Marcus theory. The reaction dynamics from dioxetane to the formaldehyde molecules do not follow the intrinsic reaction coordinate or involve trapping in the gauche .O-CH2-CH2-O. biradical potential energy minimum. Important non-statistical dynamics are exhibited for this reactive system.

Surface-induced dissociation: a unique tool for studying energetics and kinetics of the gas-phase fragmentation of large ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laskin, Julia

2015-01-01

Surface-induced dissociation (SID) is valuable tool for investigating activation and dissociation of large ions in tandem mass spectrometry. This account summarizes key findings from studies of the energetics and mechanisms of complex ion dissociation, in which SID experiments were combined with Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental data. These studies used time- and collision-energy-resolved SID experiments and SID combined with resonant ejection of selected fragment ions on a specially designed Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Fast ion activation by collision with a surface combined with the long and variable timescale of a FT-ICR MS is perfectlymore » suited for studying the energetics and dynamics of complex ion dissociation in the gas phase. Modeling of time- and collision-energy-resolved SID enables accurate determination of energy and entropy effects in the dissociation process. It has been demonstrated that entropy effects play an important role in determining the dissociation rates of both covalent and non-covalent bonds in large gaseous ions. SID studies have provided important insights on the competition between charge-directed and charge-remote fragmentation in even-electron peptide ions and the role of charge and radical site on the energetics of the dissociation of odd-electron peptide ions. Furthermore, this work examined factors that affect the strength of non-covalent binding, as well as the competition between covalent and non-covalent bond cleavages and between proton and electron transfer in model systems. Finally, SID studies have been used to understand the factors affecting nucleation and growth of clusters in solution and the gas phase.« less

Deep tunneling in the unimolecular decay of CH 3CHOO Criegee intermediates to OH radical products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Yi; Liu, Fang; Barber, Victoria P.

Unimolecular decay of Criegee intermediates produced in alkene ozonolysis is known to be a significant source of OH radicals in the troposphere. In this work, unimolecular decay of the methyl-substituted Criegee intermediate, syn-CH 3CHOO, to OH products is shown to occur at energies significantly below the transition state barrier for a 1,4 hydrogen transfer that leads to these products [Y. Fang et al., J. Chem. Phys. 144, 061102 (2016)]. The rate of appearance of OH products arising from tunneling through the barrier is obtained through direct time-domain measurements following the vibrational activation of syn-CH 3CHOO. IR excitation of syn-CH 3CHOOmore » at energies nearly 2000 cm -1 below the barrier is achieved through combination bands involving CH stretch and another lower frequency mode, and the resultant OH products are detected by UV laser-induced fluorescence. The observed syn-CH 3CHOO combination bands in the 4100–4350 cm -1 region are identified by comparison with the computed IR absorption spectrum. The experimental decay rates are found to be ca. 106 s -1 in this deep tunneling regime, which is approximately 100-times slower than that in the vicinity of the barrier.The experimental results are consistent with statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of the microcanonical decay rates with tunneling through the barrier, and notable deviations may originate from the sparsity in the density of states for syn-CH 3CHOO at lower energies. Thermal unimolecular decay of syn-CH 3CHOO is predicted to have significant contribution from microcanonical rates at energies that are much below the barrier.« less

Ab Initio Chemical Kinetics for the CH3 + O((3)P) Reaction and Related Isomerization-Decomposition of CH3O and CH2OH Radicals.

PubMed

Xu, Z F; Raghunath, P; Lin, M C

2015-07-16

The kinetics and mechanism of the CH3 + O reaction and related isomerization-decomposition of CH3O and CH2OH radicals have been studied by ab initio molecular orbital theory based on the CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVTZ, CCSD/aug-cc-pVDZ, and G2M//B3LYP/6-311+G(3df,2p) levels of theory. The predicted potential energy surface of the CH3 + O reaction shows that the CHO + H2 products can be directly generated from CH3O by the TS3 → LM1 → TS7 → LM2 → TS4 path, in which both LM1 and LM2 are very loose and TS7 is roaming-like. The result for the CH2O + H reaction shows that there are three low-energy barrier processes including CH2O + H → CHO + H2 via H-abstraction and CH2O + H → CH2OH and CH2O + H → CH3O by addition reactions. The predicted enthalpies of formation of the CH2OH and CH3O radicals at 0 K are in good agreement with available experimental data. Furthermore, the rate constants for the forward and some key reverse reactions have been predicted at 200-3000 K under various pressures. Based on the new reaction pathway for CH3 + O, the rate constants for the CH2O + H and CHO + H2 reactions were predicted with the microcanonical variational transition-state/Rice-Ramsperger-Kassel-Marcus (VTST/RRKM) theory. The predicted total and individual product branching ratios (i.e., CO versus CH2O) are in good agreement with experimental data. The rate constant for the hydrogen abstraction reaction of CH2O + H has been calculated by the canonical variational transition-state theory with quantum tunneling and small-curvature corrections to be k(CH2O + H → CHO + H2) = 2.28 × 10(-19) T(2.65) exp(-766.5/T) cm(3) molecule(-1) s(-1) for the 200-3000 K temperature range. The rate constants for the addition giving CH3O and CH2OH and the decomposition of the two radicals have been calculated by the microcanonical RRKM theory with the time-dependent master equation solution of the multiple quantum well system in the 200-3000 K temperature range at 1 Torr to 100 atm. The predicted rate constants are in good agreement with most of the available data.

Energetics and dynamics through time-resolved measurements in mass spectrometry

NASA Astrophysics Data System (ADS)

Lifshitz, Chava

Results of recent work on time-resolved photoionization and electron ionization mass spectrometry carried out in Jerusalem are reviewed. Time-resolved photoionization mass spectrometry in the vacuum ultraviolet is applied to polycyclic aromatic hydrocarbons, for example naphthalene, pyrene and fluoranthene as well as to some bromo derivatives (bromonaphthalene and bromoanthracene). Time-resolved photoionization efficiency curves are modelled by Rice-Ramsperger-Kassel-Marcus QET rate-energy k ( E ) dependences of the unimolecular dissociative processes and by the rate process infrared radiative relaxation k . Experimental results are augmented by time-resolved photorad dissociation data for the same species, whenever available. Kinetic shifts, conventional and intrinsic (due to competition between dissociative and radiative decay), are evaluated. Activation parameters (activation energies and entropies) are deduced. Thermochemical information is obtained including bond energies and ionic heats of formation. Fullerenes, notably C , are studied by time-resolved electron ionization and a large intrinsic shift, due to competition with black-bodylike radiative decay in the visible is discussed.

Topographies and dynamics on multidimensional potential energy surfaces

NASA Astrophysics Data System (ADS)

Ball, Keith Douglas

The stochastic master equation is a valuable tool for elucidating potential energy surface (PES) details that govern structural relaxation in clusters, bulk systems, and protein folding. This work develops a comprehensive framework for studying non-equilibrium relaxation dynamics using the master equation. Since our master equations depend upon accurate partition function models for use in Rice-Ramsperger-Kassel-Marcus (RRK(M) transition state theory, this work introduces several such models employing various harmonic and anharmonic approximations and compares their predicted equilibrium population distributions with those determined from molecular dynamics. This comparison is performed for the fully-delineated surfaces (KCl)5 and Ar9 to evaluate model performance for potential surfaces with long- and short-range interactions, respectively. For each system, several models perform better than a simple harmonic approximation. While no model gives acceptable results for all minima, and optimal modeling strategies differ for (KCl)5 and Ar9, a particular one-parameter model gives the best agreement with simulation for both systems. We then construct master equations from these models and compare their isothermal relaxation predictions for (KCl)5 and Ar9 with molecular dynamics simulations. This is the first comprehensive test of the kinetic performance of partition function models of its kind. Our results show that accurate modeling of transition-state partition functions is more important for (KCl)5 than for Ar9 in reproducing simulation results, due to a marked stiffening anharmonicity in the transition-state normal modes of (KCl)5. For both systems, several models yield qualitative agreement with simulation over a large temperature range. To examine the robustness of the master equation when applied to larger systems, for which full topographical descriptions would be either impossible or infeasible, we compute relaxation predictions for Ar11 using a master equation constructed from data representing the full PES, and compare these predictions to those of reduced master equations based on statistical samples of the full PES. We introduce a sampling method which generates random, Boltzmann-weighted, energetically 'downhill' sequences. The study reveals that, at moderate temperatures, the slowest relaxation timescale converges as the number of sequences in a sample grows to ~1000. Furthermore, the asymptotic timescale is comparable to the full-PES value.

RRKM and master equation kinetic analysis of parallel addition reactions of isomeric radical intermediates in hydrocarbon flames

NASA Astrophysics Data System (ADS)

Winter, Pierre M.; Rheaume, Michael; Cooksy, Andrew L.

2017-08-01

We have calculated the temperature-dependent rate coefficients of the addition reactions of butadien-2-yl (C4H5) and acroylyl (C3H3O) radicals with ethene (C2H4), carbon monoxide (CO), formaldehyde (H2CO), hydrogen cyanide (HCN), and ketene (H2CCO), in order to explore the balance between kinetic and thermodynamic control in these combustion-related reactions. For the C4H5 radical, the 1,3-diene form of the addition products is more stable than the 1,2-diene, but the 1,2-diene form of the radical intermediate is stabilized by an allylic delocalization, which may influence the relative activation energies. For the reactions combining C3H3O with C2H4, CO, and HCN, the opposite is true: the 1,2-enone form of the addition products is more stable than the 1,3-enone, whereas the 1,3-enone is the slightly more stable radical species. Optimized geometries and vibrational modes were computed with the QCISD/aug-cc-pVDZ level and basis, followed by single-point CCSD(T)-F12a/cc-pVDZ-F12 energy calculations. Our findings indicate that the kinetics in all cases favor reaction along the 1,3 pathway for both the C4H5 and C3H3O systems. The Rice-Ramsperger-Kassel-Marcus (RRKM) microcanonical rate coefficients and subsequent solution of the chemical master equation were used to predict the time-evolution of our system under conditions from 500 K to 2000 K and from 10-5 bar to 10 bars. Despite the 1,3 reaction pathway being more favorable for the C4H5 system, our results predict branching ratios of the 1,2 to 1,3 product as high as 0.48 at 1 bar. Similar results hold for the acroylyl system under these combustion conditions, suggesting that under kinetic control the branching of these reactions may be much more significant than the thermodynamics would suggest. This effect may be partly attributed to the low energy difference between 1,2 and 1,3 forms of the radical intermediate. No substantial pressure-dependence is found for the overall forward reaction rates until pressures decrease below 0.1 bar.

Dual fluorescence of excited state intra-molecular proton transfer of HBFO: mechanistic understanding, substituent and solvent effects.

PubMed

Yang, Wenjing; Chen, Xuebo

2014-03-07

A combined approach of the multiconfigurational perturbation theory with the Rice-Ramsperger-Kassel-Marcus methodology has been employed to calculate the minimum potential energy profiles and the rates of excited state intra-molecular proton transfer (ESIPT) for the WOLED material molecule of HBFO and its four meta- or para-substituted compounds in gas phase, acetonitrile and cyclohexane solvents. The kinetic control for these reactions is quantitatively determined and extensively studied on the basis of the accurate potential energy surfaces when the thermodynamic factor associated with the free energy change becomes negligible in the case of the existence of a significant barrier in the ESIPT process. These computational efforts contribute to a deep understanding of the ESIPT mechanism, dual emission characteristics, kinetic controlling factor, substituent and solvent effects for these material molecules. The white light emission is generated by the establishment of dynamic equilibrium between enol and keto forms in the charge transfer excited SCT((1)ππ*) state. The performance of white light emission is quantitatively demonstrated to be mainly sensitive to the molecular tailoring approach of the electronic properties of meta- or para- substituents by the modulation of the forward/backward ESIPT rate ratio. The quality of white light emission is slightly tunable through its surrounding solvent environment. These computational results will provide a useful strategy for the molecular design of OLED and WOLED materials.

Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

NASA Astrophysics Data System (ADS)

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-Hinshelwood model and Rice, Ramsperger, Kassel and Marcus (RRKM) theory) were also carried out and obtained data fitted the Arrhenius equations.

Direct observation of unimolecular decay of CH 3 CH 2 CHOO Criegee intermediates to OH radical products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Yi; Liu, Fang; Klippenstein, Stephen J.

2016-07-28

The unimolecular decay of carbonyl oxide intermediates, known as Criegee intermediates, produced in alkene ozonolysis is a significant source of OH radicals in the troposphere. Here, the rate of appearance of OH radical products is examined directly in the time-domain for a prototypical alkyl-substituted Criegee intermediate, CH3CH2CHOO, following vibrational activation under collision-free conditions. Complementary statistical Rice-Ramsperger-Kassel-Marcus calculations of the microcanonical unimolecular decay rate for CH3CH2CHOO are also carried out at energies in the vicinity of the barrier for 1,4 hydrogen atom transfer that leads to OH products. Tunneling through the barrier, derived from high level electronic structure calculations, contributes significantlymore » to the decay rate. Infrared transitions of CH3CH2CHOO are identified in the CH stretch overtone region, which are detected by ultraviolet laser-induced fluorescence of the resultant OH products. The features observed are attributed to CH vibrational excitations and conformational forms utilizing insights from theory. Both experiment and theory yield unimolecular decay rates for CH3CH2CHOO of ca. 10(7) s(-1), which are slower than those obtained for syn-CH3CHOO or (CH3)(2)COO reported previously [Fang et al., J. Chem. Phys. 144, 061102 (2016)] at similar energies. Master equation modeling is also utilized to predict the thermal decay rate of CH3CH2CHOO under atmospheric conditions, giving a rate of 279 s(-1) at 298 K.« less

Ab initio investigation of the thermal decomposition of n-butylcyclohexane.

PubMed

Ali, Mohamad Akbar; Dillstrom, V Tyler; Lai, Jason Y W; Violi, Angela

2014-02-13

Environmental and energy security concerns have motivated an increased focus on developing clean, efficient combustors, which increasingly relies on insight into the combustion chemistry of fuels. In particular, naphthenes (cycloalkanes and alkylcycloalkanes) are important chemical components of distillate fuels, such as diesel and jet fuels. As such, there is a growing interest in describing napthene reactivity with kinetic mechanisms. Use of these mechanisms in predictive combustion models aids in the development of combustors. This study focuses on the pyrolysis of n-butylcyclohexane (n-BCH), an important representative of naphthenes in jet fuels. Seven different unimolecular decomposition pathways of C-C bond fission were explored utilizing ab initio/DFT methods. Accurate reaction energies were computed using the high-level quantum composite G3B3 method. Variational transition state theory, Rice-Ramsperger-Kassel-Marcus/master equation simulations provided temperature- and pressure-dependent rate constants. Implementation of these pathways into an existing chemical kinetic mechanism improved the prediction of experimental OH radical and H2O speciation in shock tube oxidation. Simulations of this combustion showed a change in the expected decomposition chemistry of n-BCH, predicting increased production of cyclic alkyl radicals instead of straight-chain alkenes. The most prominent reaction pathway for the decomposition of n-BCH is n-BCH = C3H7 + C7H13. The results of this study provide insight into the combustion of n-BCH and will aid in the future development of naphthene kinetic mechanisms.

Penning ionization and ion fragmentation of formamide HCONH2 by He∗, Ne∗, and Ar∗ in molecular beams

NASA Astrophysics Data System (ADS)

Madison, Tamika A.; Siska, P. E.

2009-10-01

Mass spectra from Penning ionization by metastable atom bombardment (MAB) in the title system at kinetic energies near 1 kcal/mol are reported. The experiments employ a supersonic excited noble gas beam crossing an effusive beam of formamide vapor. Product ions are extracted perpendicular to the plane of the beams, analyzed by a quadrupole mass filter, and counted by a scintillation-type ion counter. Relative to 70 eV electron impact, the He∗ and Ne∗ spectra show more extensive breakage of C-N and C-H bonds despite the smaller available energy, while the Ar∗ spectrum shows only the molecular ion (m /z 45), H atom elimination (44), and the decarbonylation products CO+NH3+ (17). Fragmentation in the latter system has been analyzed using a combination of ab initio calculations and Rice-Ramsperger-Kassel-Marcus theory with tunneling correction; good agreement with the experimental 45/44/17 intensity ratio 100/6.8±0.7/6.2±1.7 is obtained. 15% of m/z 17 and 50% of m /z 44 is attributed to tunneling. The ab initio decarbonylation reaction path yields a hydrogen bonded H2N-HCO+ transition state, which transfers a proton while proceeding downhill to the observed products, while both the path and the energetics support the earlier conclusion that the lowest lying electronically excited state of the ion (2π or 2a″) crosses the ground state early along the reaction path, thereby dominating the dynamics of decarbonylation.

CN radical reactions with hydrogen cyanide and cyanogen - Comparison of theory and experiment

NASA Technical Reports Server (NTRS)

Yang, D. L.; Yu, T.; Lin, M. C.; Melius, C. F.

1992-01-01

The method of laser photolysis/laser-induced fluorescence is used to obtain absolute rate constants for CN radical reactions with HCN and C2N2. The rate constants were found to be temperature-dependent in the range 300-740 K and pressure independent in the range 100-600 Torr. Rice-Remsperger-Kassel-Marcus theory for both reactions employing the transition state parameters obtained by the BAC-MP4 method are made. These calculations yielded reasonable results for the CN + HCN reaction, predicting both the temperature dependence and pressure independence. No pressure effect was observed in the pressure range 100-1000 Torr at temperatures below 900 K, confirming the experimental results.

Mechanistic and kinetic study of the CH3CO + O2 reaction.

PubMed

Hou, Hua; Li, Aixiao; Hu, Hongyi; Li, Yuzhen; Li, Hui; Wang, Baoshan

2005-06-08

Potential-energy surface of the CH3CO + O2 reaction has been calculated by ab initio quantum chemistry methods. The geometries were optimized using the second-order Moller-Plesset theory (MP2) with the 6-311G(d,p) basis set and the coupled-cluster theory with single and double excitations (CCSD) with the correlation consistent polarized valence double zeta (cc-pVDZ) basis set. The relative energies were calculated using the Gaussian-3 second-order Moller-Plesset theory with the CCSD/cc-pVDZ geometries. Multireference self-consistent-field and MP2 methods were also employed using the 6-311G(d,p) and 6-311++G(3df,2p) basis sets. Both addition/elimination and direct abstraction mechanisms have been investigated. It was revealed that acetylperoxy radical [CH3C(O)OO] is the initial adduct and the formation of OH and alpha-lactone [CH2CO2(1A')] is the only energetically accessible decomposition channel. The other channels, e.g., abstraction, HO2 + CH2CO, O + CH3CO2, CO + CH3O2, and CO2 + CH3O, are negligible. Multichannel Rice-Ramsperger-Kassel-Marcus theory and transition state theory (E-resolved) were employed to calculate the overall and individual rate coefficients and the temperature and pressure dependences. Fairly good agreement between theory and experiments has been obtained without any adjustable parameters. It was concluded that at pressures below 3 Torr, OH and CH2CO2(1A') are the major nascent products of the oxidation of acetyl radicals, although CH2CO2(1A') might either undergo unimolecular decomposition to form the final products of CH2O + CO or react with OH and Cl to generate H2O and HCl. The acetylperoxy radicals formed by collisional stabilization are the major products at the elevated pressures. In atmosphere, the yield of acetylperoxy is nearly unity and the contribution of OH is only marginal.

Hydrogen scrambling in ethane induced by intense laser fields: statistical analysis of coincidence events.

PubMed

Kanya, Reika; Kudou, Tatsuya; Schirmel, Nora; Miura, Shun; Weitzel, Karl-Michael; Hoshina, Kennosuke; Yamanouchi, Kaoru

2012-05-28

Two-body Coulomb explosion processes of ethane (CH(3)CH(3)) and its isotopomers (CD(3)CD(3) and CH(3)CD(3)) induced by an intense laser field (800 nm, 1.0 × 10(14) W/cm(2)) with three different pulse durations (40 fs, 80 fs, and 120 fs) are investigated by a coincidence momentum imaging method. On the basis of statistical treatment of the coincidence data, the contributions from false coincidence events are estimated and the relative yields of the decomposition pathways are determined with sufficiently small uncertainties. The branching ratios of the two body decomposition pathways of CH(3)CD(3) from which triatomic hydrogen molecular ions (H(3)(+), H(2)D(+), HD(2)(+), D(3)(+)) are ejected show that protons and deuterons within CH(3)CD(3) are scrambled almost statistically prior to the ejection of a triatomic hydrogen molecular ion. The branching ratios were estimated by statistical Rice-Ramsperger-Kassel-Marcus calculations by assuming a transition state with a hindered-rotation of a diatomic hydrogen moiety. The hydrogen scrambling dynamics followed by the two body decomposition processes are discussed also by using the anisotropies in the ejection directions of the fragment ions and the kinetic energy distribution of the two body decomposition pathways.

Understanding ligand effects in gold clusters using mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Grant E.; Laskin, Julia

This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because “each-atom-counts” toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation ofmore » numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted that may be compared with the results of high-level theoretical calculations. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well-defined surfaces may be explored using ion soft landing (SL) in a custom-built instrument combined with in situ time of flight secondary ion mass spectrometry (TOF-SIMS). Jointly, this multipronged experimental approach allows characterization of the full spectrum of relevant phenomena including cluster synthesis, ligand exchange, thermochemistry, surface immobilization, and reactivity. The fundamental insights obtained from this work will facilitate the directed synthesis of gold clusters with predetermined size and properties for specific applications.« less

Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

NASA Astrophysics Data System (ADS)

Lüttgens, G.; Pontius, N.; Bechthold, P. S.; Neeb, M.; Eberhardt, W.

2002-02-01

Thermal CO desorption from photoexcited free metal-carbonyl clusters has been resolved in real time using two-color pump-probe photoelectron spectroscopy. Sequential energy dissipation steps between the initial photoexcitation and the final desorption event, e.g., electron relaxation and thermalization, have been resolved for Au2(CO)- and Pt2(CO)-5. The desorption rates for the two clusters differ considerably due to the different numbers of vibrational degrees of freedom. The unimolecular CO-desorption thresholds of Au2(CO)- and Pt2(CO)-5 have been approximated by means of a statistical Rice-Ramsperger-Kassel calculation using the experimentally derived desorption rate constants.

Molecular elimination of Br2 in photodissociation of CH2BrC(O)Br at 248 nm using cavity ring-down absorption spectroscopy.

PubMed

Fan, He; Tsai, Po-Yu; Lin, King-Chuen; Lin, Cheng-Wei; Yan, Chi-Yu; Yang, Shu-Wei; Chang, A H H

2012-12-07

The primary elimination channel of bromine molecule in one-photon dissociation of CH(2)BrC(O)Br at 248 nm is investigated using cavity ring-down absorption spectroscopy. By means of spectral simulation, the ratio of nascent vibrational population in v = 0, 1, and 2 levels is evaluated to be 1:(0.5 ± 0.1):(0.2 ± 0.1), corresponding to a Boltzmann vibrational temperature of 581 ± 45 K. The quantum yield of the ground state Br(2) elimination reaction is determined to be 0.24 ± 0.08. With the aid of ab initio potential energy calculations, the obtained Br(2) fragments are anticipated to dissociate on the electronic ground state, yielding vibrationally hot Br(2) products. The temperature-dependence measurements support the proposed pathway via internal conversion. For comparison, the Br(2) yields are obtained analogously from CH(3)CHBrC(O)Br and (CH(3))(2)CBrC(O)Br to be 0.03 and 0.06, respectively. The trend of Br(2) yields among the three compounds is consistent with the branching ratio evaluation by Rice-Ramsperger-Kassel-Marcus method. However, the latter result for each molecule is smaller by an order of magnitude than the yield findings. A non-statistical pathway so-called roaming process might be an alternative to the Br(2) production, and its contribution might account for the underestimate of the branching ratio calculations.

Dynamically biased statistical model for the ortho/para conversion in the H2 + H3+ → H3+ + H2 reaction.

PubMed

Gómez-Carrasco, Susana; González-Sánchez, Lola; Aguado, Alfredo; Sanz-Sanz, Cristina; Zanchet, Alexandre; Roncero, Octavio

2012-09-07

In this work we present a dynamically biased statistical model to describe the evolution of the title reaction from statistical to a more direct mechanism, using quasi-classical trajectories (QCT). The method is based on the one previously proposed by Park and Light [J. Chem. Phys. 126, 044305 (2007)]. A recent global potential energy surface is used here to calculate the capture probabilities, instead of the long-range ion-induced dipole interactions. The dynamical constraints are introduced by considering a scrambling matrix which depends on energy and determine the probability of the identity/hop/exchange mechanisms. These probabilities are calculated using QCT. It is found that the high zero-point energy of the fragments is transferred to the rest of the degrees of freedom, what shortens the lifetime of H(5)(+) complexes and, as a consequence, the exchange mechanism is produced with lower proportion. The zero-point energy (ZPE) is not properly described in quasi-classical trajectory calculations and an approximation is done in which the initial ZPE of the reactants is reduced in QCT calculations to obtain a new ZPE-biased scrambling matrix. This reduction of the ZPE is explained by the need of correcting the pure classical level number of the H(5)(+) complex, as done in classical simulations of unimolecular processes and to get equivalent quantum and classical rate constants using Rice-Ramsperger-Kassel-Marcus theory. This matrix allows to obtain a ratio of hop/exchange mechanisms, α(T), in rather good agreement with recent experimental results by Crabtree et al. [J. Chem. Phys. 134, 194311 (2011)] at room temperature. At lower temperatures, however, the present simulations predict too high ratios because the biased scrambling matrix is not statistical enough. This demonstrates the importance of applying quantum methods to simulate this reaction at the low temperatures of astrophysical interest.

Dynamically biased statistical model for the ortho/para conversion in the H2+H3+ --> H3++ H2 reaction

NASA Astrophysics Data System (ADS)

Gómez-Carrasco, Susana; González-Sánchez, Lola; Aguado, Alfredo; Sanz-Sanz, Cristina; Zanchet, Alexandre; Roncero, Octavio

2012-09-01

In this work we present a dynamically biased statistical model to describe the evolution of the title reaction from statistical to a more direct mechanism, using quasi-classical trajectories (QCT). The method is based on the one previously proposed by Park and Light [J. Chem. Phys. 126, 044305 (2007), 10.1063/1.2430711]. A recent global potential energy surface is used here to calculate the capture probabilities, instead of the long-range ion-induced dipole interactions. The dynamical constraints are introduced by considering a scrambling matrix which depends on energy and determine the probability of the identity/hop/exchange mechanisms. These probabilities are calculated using QCT. It is found that the high zero-point energy of the fragments is transferred to the rest of the degrees of freedom, what shortens the lifetime of H_5^+ complexes and, as a consequence, the exchange mechanism is produced with lower proportion. The zero-point energy (ZPE) is not properly described in quasi-classical trajectory calculations and an approximation is done in which the initial ZPE of the reactants is reduced in QCT calculations to obtain a new ZPE-biased scrambling matrix. This reduction of the ZPE is explained by the need of correcting the pure classical level number of the H_5^+ complex, as done in classical simulations of unimolecular processes and to get equivalent quantum and classical rate constants using Rice-Ramsperger-Kassel-Marcus theory. This matrix allows to obtain a ratio of hop/exchange mechanisms, α(T), in rather good agreement with recent experimental results by Crabtree et al. [J. Chem. Phys. 134, 194311 (2011), 10.1063/1.3587246] at room temperature. At lower temperatures, however, the present simulations predict too high ratios because the biased scrambling matrix is not statistical enough. This demonstrates the importance of applying quantum methods to simulate this reaction at the low temperatures of astrophysical interest.

Oxidation Dynamics of Methionine with Singlet Oxygen: Effects of Methionine Ionization and Microsolvation.

PubMed

Liu, Fangwei; Liu, Jianbo

2015-06-25

We report an in-depth study on the gas-phase reactions of singlet O2[a(1)Δg] with methionine (Met) at different ionization and hydration states (including deprotonated [Met - H](-), hydrated deprotonated [Met - H](-)(H2O)1,2, and hydrated protonated MetH(+)(H2O)1,2), using guided-ion-beam scattering mass spectrometry. The measurements include the effects of collision energy (Ecol) on reaction cross sections over a center-of-mass Ecol range from 0.05 to 1.0 eV. The aim of this study is to probe the influences of Met ionization and hydration on its oxidation mechanism and dynamics. Density functional theory calculations, Rice-Ramsperger-Kassel-Marcus modeling, and quasi-classical, direct dynamics trajectory simulations were performed to examine the properties of various complexes and transition states that might be important along reaction coordinates, probe reaction potential energy surfaces, and to establish the atomic-level mechanism for the Met oxidation process. No oxidation products were observed for the reaction of [Met - H](-) with (1)O2 due to the high-energy barriers located in the product channels for this system. However, this nonreactive property was altered by the microsolvation of [Met - H](-); as a result, hydroperoxides were captured as the oxidation products for [Met - H](-)(H2O)1,2 + (1)O2. For the reaction of MetH(+)(H2O)1,2 + (1)O2, besides formation of hydroperoxides, an H2O2 elimination channel was observed. The latter channel is similar to what was found in the reaction of dehydrated MetH(+) with (1)O2 (J. Phys. Chem. B 2011, 115, 2671). The reactions of hydrated protonated and deprotonated Met are all inhibited by Ecol, becoming negligible at Ecol ≥ 0.5 eV. The kinetic and dynamical consequences of microsolvation on Met oxidation and their biological implications are discussed.

Is Photolytic Production a Viable Source of HCN and HNC in Astrophysical Environments? A Laboratory-based Feasibility Study of Methyl Cyanoformate

NASA Astrophysics Data System (ADS)

Wilhelm, Michael J.; Martínez-Núñez, Emilio; González-Vázquez, Jesús; Vázquez, Saulo A.; Smith, Jonathan M.; Dai, Hai-Lung

2017-11-01

Motivated by the possibility that cyano-containing hydrocarbons may act as photolytic sources for HCN and HNC in astrophysical environments, we conducted a combined experimental and theoretical investigation of the 193 nm photolysis of the cyano-ester, methyl cyanoformate (MCF). Experimentally, nanosecond time-resolved infrared emission spectroscopy was used to detect the emission from nascent products generated in the photolysis reaction. The time-resolved spectra were analyzed using a recently developed spectral reconstruction analysis, which revealed spectral bands assignable to HCN and HNC. Fitting of the emission band shape and intensity allowed determination of the photolysis quantum yields of HCN, HNC, and {CN}({A}2{{{\\Pi }}}1) and an HNC/HCN ratio of ˜0.076 ± 0.059. Additionally, multiconfiguration self-consistent field calculations were used to characterize photoexcitation-induced reactions in the ground and four lowest singlet excited states of MCF. At 193 nm excitation, dissociation is predicted to occur predominantly on the repulsive S 2 state, with minor pathways via internal conversion from S 2 to highly excited ground state. An automated transition-state search algorithm was employed to identify the corresponding ground-state dissociation channels, and Rice-Ramsperger-Kassel-Marcus and Kinetic Monte Carlo simulations were used to calculate the associated branching ratios. The proposed mechanisms were validated using the experimentally measured and quasi-classical trajectory-deduced nascent internal energy distributions of HCN and HNC. This work, along with previous studies, illustrates the propensity for cyano-containing hydrocarbons to act as photolytic sources for astrophysical HCN and HNC and may help explain the observed overabundance of HNC in astrophysical environments.

Shattering of SiMe3+ during surface-induced dissociation

NASA Astrophysics Data System (ADS)

Schultz, David G.; Hanley, Luke

1998-12-01

We provide experimental evidence that upon hyperthermal impact of Si(CD3)3+ ions with an organic surface, a portion of the ions undergo dissociation while still in contact with the surface. We use a tandem configuration of quadrupole mass spectrometers along with an energy analyzer to measure the kinetic energy distributions of the fragments that form as a result of the surface scattering of 25 eV Si(CD3)3+. These distributions are different for scattering from a clean Au(111) surface versus scattering from an organic surface composed of a self-assembled monolayer of hexanethiolate on Au(111). Parent and fragment ions recoil from the clean Au(111) surface with the same velocity, as is expected for fragmentation away from the surface. However, the same scattering products recoil from the organic surface with different velocities but similar energies, suggesting that the fragmentation dynamics are modified by surface interactions. We perform molecular dynamics simulations which predict residence times of ˜210 fs at the organic surface and ˜20 fs at the Au surface. The simulations also predict that 13% and 31% of the ions fragment within 1.1 ps of surface impact at the organic and Au surfaces, respectively. Thus, the experimental observation of dissociation at only the organic surface results from its longer ion-surface interaction time. The fragmentation time scale predicted by Rice-Ramsperger-Kassel-Marcus calculations is yet longer, suggesting that at least a portion of the surface-induced dissociation of Si(CD3)3+ may occur via a nonstatistical mechanism. Our interpretation draws heavily from an analogous "shattering" mechanism previously proposed for cluster-surface scattering [E. Hendell, U. Even, T. Raz, and R. D. Levine, Phys. Rev. Lett. 75, 2670 (1995)].

O2(a1Δg) + Mg, Fe, and Ca: Experimental kinetics and formulation of a weak collision, multiwell master equation with spin-hopping

NASA Astrophysics Data System (ADS)

Plane, J. M. C.; Whalley, C. L.; Frances-Soriano, L.; Goddard, A.; Harvey, J. N.; Glowacki, D. R.; Viggiano, A. A.

2012-07-01

The first excited electronic state of molecular oxygen, O2(a1Δg), is formed in the upper atmosphere by the photolysis of O3. Its lifetime is over 70 min above 75 km, so that during the day its concentration is about 30 times greater than that of O3. In order to explore its potential reactivity with atmospheric constituents produced by meteoric ablation, the reactions of Mg, Fe, and Ca with O2(a) were studied in a fast flow tube, where the metal atoms were produced either by thermal evaporation (Ca and Mg) or by pulsed laser ablation of a metal target (Fe), and detected by laser induced fluorescence spectroscopy. O2(a) was produced by bubbling a flow of Cl2 through chilled alkaline H2O2, and its absolute concentration determined from its optical emission at 1270 nm (O2(a1Δg - X3Σg-). The following results were obtained at 296 K: k(Mg + O2(a) + N2 → MgO2 + N2) = (1.8 ± 0.2) × 10-30 cm6 molecule-2 s-1; k(Fe + O2(a) → FeO + O) = (1.1 ± 0.1) × 10-13 cm3 molecule-1 s-1; k(Ca + O2(a) + N2 → CaO2 + N2) = (2.9 ± 0.2) × 10-28 cm6 molecule-2 s-1; and k(Ca + O2(a) → CaO + O) = (2.7 ± 1.0) × 10-12 cm3 molecule-1 s-1. The total uncertainty in these rate coefficients, which mostly arises from the systematic uncertainty in the O2(a) concentration, is estimated to be ±40%. Mg + O2(a) occurs exclusively by association on the singlet surface, producing MgO2(1A1), with a pressure dependent rate coefficient. Fe + O2(a), on the other hand, shows pressure independent kinetics. FeO + O is produced with a probability of only ˜0.1%. There is no evidence for an association complex, suggesting that this reaction proceeds mostly by near-resonant electronic energy transfer to Fe(a5F) + O2(X). The reaction of Ca + O2(a) occurs in an intermediate regime with two competing pressure dependent channels: (1) a recombination to produce CaO2(1A1), and (2) a singlet/triplet non-adiabatic hopping channel leading to CaO + O(3P). In order to interpret the Ca + O2(a) results, we utilized density functional theory along with multireference and explicitly correlated CCSD(T)-F12 electronic structure calculations to examine the lowest lying singlet and triplet surfaces. In addition to mapping stationary points, we used a genetic algorithm to locate minimum energy crossing points between the two surfaces. Simulations of the Ca + O2(a) kinetics were then carried out using a combination of both standard and non-adiabatic Rice-Ramsperger-Kassel-Marcus (RRKM) theory implemented within a weak collision, multiwell master equation model. In terms of atmospheric significance, only in the case of Ca does reaction with O2(a) compete with O3 during the daytime between 85 and 110 km.

Molecular dynamics studies of the thermal decomposition of 2,3-diazabicyclo(2.2.1)hept-2-ene

NASA Astrophysics Data System (ADS)

Sorescu, Dan C.; Thompson, Donald L.; Raff, Lionel M.

1995-05-01

The reaction dynamics of the thermal gas-phase decomposition of 2,3-diazabicyclo (2.2.1)hept-2-ene-exo, exo-5,6-d2 have been investigated using classical trajectory methods on a semiempirical potential-energy surface. The global potential is written as a superposition of different reaction channel potentials containing bond stretching, bending and torsional terms, connected by parametrized switching functions. Reaction channels for stepwise and concerted cleavage of the two C-N bonds of the reactant have both been considered in construction of the potential. The geometries of 2,3-diazabicyclo(2.2.1)hept-2-ene, the diazenyl biradical and of the transition state corresponding to breaking of the remaining C-N bond of diazenyl biradical have been determined at the second order Möller-Plesset perturbation theory (MP2/6-31G*) and at Hartree-Fock (HF/6-31G*) levels, respectively. The bond dissociation energies have been estimated using the available thermochemical data and previously reported results for bicyclo(2.1.0)pentane [J. Chem. Phys. 101, 3729 (1994)]. The equilibrium geometries predicted by the semiempirical potential for reactants and products, the barrier height for thermal nitrogen extrusion from 2,3-diazabicyclo(2.2.1)hept-2-ene and the fundamental vibrational frequencies are in good to excellent agreement with the measured or ab initio calculated values. Using a projection method of the instantaneous Cartesian velocities onto the normal mode vectors and classical trajectory calculations, the dissociation dynamics of 2,3-diazabicyclo(2.2.1)hept-2-ene-exo, exo-5,6-d2 are investigated at several excitation energies in the range 60-175 kcal/mol. The results show the following: (1) The thermal reaction takes place with a preference for inversion of configuration in the reaction products, the exo-labeled bicyclo(2.1.0) pentane being the major product. The exo/endo ratio of bicyclo(2.1.0) pentane isomers is found to vary between 1.8-2.2 for the energy range considered. (2) For random energization of the vibrational modes, the energy dependence of the rate coefficients can be described by a RRK expression. (3) The significant broadening and overlapping of the power spectral bands, together with the disappearance of characteristic features in the power spectra of the internal coordinates calculated at different energies, indicate high intramolecular vibrational redistribution rates and global statistical behavior. (4) The energy partitioning among products shows that the internal energy is preferentially distributed into the vibrational degrees of freedom in BCP, while N2 is formed with small amounts of rotational and vibrational energies. Overall, the distribution of energy among the product degrees of freedom follows statistical predictions in the internal energy range investigated. (5) Stepwise dissociation of the C-N bonds is the predominant mechanism which characterizes the N2 elimination from the parent molecule. (6) Although statistical theories of reaction rates, such as Rice-Ramsperger-Kassel-Marcus (RRKM) theory, are unable to predict the product exo/endo ratio, this is not a result of the breakdown of the statistical assumption inherent in these theories, but rather to the fact that statistical theory does not address mechanistic questions related to post transition-state events. Although the results show that there is a near microcanonical distribution of energy in the 1,3-cyclopentanediyl radical, the system does not have sufficient time to explore all of the energetically accessible configuration space prior to the closure of the 1-3 bridgehead bond. The result is a nonstatistical exo/endo product ratio that deviates from the statistically expected result of unity.

Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory.

PubMed

Bao, Junwei Lucas; Zheng, Jingjing; Truhlar, Donald G

2016-03-02

Pressure-dependent reactions are ubiquitous in combustion and atmospheric chemistry. We employ a new calibration procedure for quantum Rice-Ramsperger-Kassel (QRRK) unimolecular rate theory within a chemical activation mechanism to calculate the pressure-falloff effect of a radical association with an aromatic ring. The new theoretical framework is applied to the reaction of H with toluene, which is a prototypical reaction in the combustion chemistry of aromatic hydrocarbons present in most fuels. Both the hydrogen abstraction reactions and the hydrogen addition reactions are calculated. Our system-specific (SS) QRRK approach is adjusted with SS parameters to agree with multistructural canonical variational transition state theory with multidimensional tunneling (MS-CVT/SCT) at the high-pressure limit. The new method avoids the need for the usual empirical estimations of the QRRK parameters, and it eliminates the need for variational transition state theory calculations as a function of energy, although in this first application we do validate the falloff curves by comparing SS-QRRK results without tunneling to multistructural microcanonical variational transition state theory (MS-μVT) rate constants without tunneling. At low temperatures, the two approaches agree well with each other, but at high temperatures, SS-QRRK tends to overestimate falloff slightly. We also show that the variational effect is important in computing the energy-resolved rate constants. Multiple-structure anharmonicity, torsional-potential anharmonicity, and high-frequency-mode vibrational anharmonicity are all included in the rate computations, and torsional anharmonicity effects on the density of states are investigated. Branching fractions, which are both temperature- and pressure-dependent (and for which only limited data is available from experiment), are predicted as a function of pressure.

Modeling collision energy transfer in APCI/CID mass spectra of PAHs using thermal-like post-collision internal energy distributions

NASA Astrophysics Data System (ADS)

Solano, Eduardo A.; Mohamed, Sabria; Mayer, Paul M.

2016-10-01

The internal energy transferred when projectile molecular ions of naphthalene collide with argon gas atoms was extracted from the APCI-CID (atmospheric-pressure chemical ionization collision-induced dissociation) mass spectra acquired as a function of collision energy. Ion abundances were calculated by microcanonical integration of the differential rate equations using the Rice-Ramsperger-Kassel-Marcus rate constants derived from a UB3LYP/6-311G+(3df,2p)//UB3LYP/6-31G(d) fragmentation mechanism and thermal-like vibrational energy distributions p M (" separators=" E , T char ) . The mean vibrational energy excess of the ions was characterized by the parameter Tchar ("characteristic temperature"), determined by fitting the theoretical ion abundances to the experimental breakdown graph (a plot of relative abundances of the ions as a function of kinetic energy) of activated naphthalene ions. According to these results, the APCI ion source produces species below Tchar = 1457 K, corresponding to 3.26 eV above the vibrational ground state. Subsequent collisions heat the ions up further, giving rise to a sigmoid curve of Tchar as a function of Ecom (center-of-mass-frame kinetic energy). The differential internal energy absorption per kinetic energy unit (dEvib/dEcom) changes with Ecom according to a symmetric bell-shaped function with a maximum at 6.38 ± 0.32 eV (corresponding to 6.51 ± 0.27 eV of vibrational energy excess), and a half-height full width of 6.30 ± 1.15 eV. This function imposes restrictions on the amount of energy that can be transferred by collisions, such that a maximum is reached as kinetic energy is increased. This behavior suggests that the collisional energy transfer exhibits a pronounced increase around some specific value of energy. Finally, the model is tested against the CID mass spectra of anthracene and pyrene ions and the corresponding results are discussed.

Modeling collision energy transfer in APCI/CID mass spectra of PAHs using thermal-like post-collision internal energy distributions.

PubMed

Solano, Eduardo A; Mohamed, Sabria; Mayer, Paul M

2016-10-28

The internal energy transferred when projectile molecular ions of naphthalene collide with argon gas atoms was extracted from the APCI-CID (atmospheric-pressure chemical ionization collision-induced dissociation) mass spectra acquired as a function of collision energy. Ion abundances were calculated by microcanonical integration of the differential rate equations using the Rice-Ramsperger-Kassel-Marcus rate constants derived from a UB3LYP/6-311G+(3df,2p)//UB3LYP/6-31G(d) fragmentation mechanism and thermal-like vibrational energy distributions p M E,T char . The mean vibrational energy excess of the ions was characterized by the parameter T char ("characteristic temperature"), determined by fitting the theoretical ion abundances to the experimental breakdown graph (a plot of relative abundances of the ions as a function of kinetic energy) of activated naphthalene ions. According to these results, the APCI ion source produces species below T char = 1457 K, corresponding to 3.26 eV above the vibrational ground state. Subsequent collisions heat the ions up further, giving rise to a sigmoid curve of T char as a function of E com (center-of-mass-frame kinetic energy). The differential internal energy absorption per kinetic energy unit (dE vib /dE com ) changes with E com according to a symmetric bell-shaped function with a maximum at 6.38 ± 0.32 eV (corresponding to 6.51 ± 0.27 eV of vibrational energy excess), and a half-height full width of 6.30 ± 1.15 eV. This function imposes restrictions on the amount of energy that can be transferred by collisions, such that a maximum is reached as kinetic energy is increased. This behavior suggests that the collisional energy transfer exhibits a pronounced increase around some specific value of energy. Finally, the model is tested against the CID mass spectra of anthracene and pyrene ions and the corresponding results are discussed.

A combined rocket-borne and ground-based study of the sodium layer and charged dust in the upper mesosphere

NASA Astrophysics Data System (ADS)

Plane, John M. C.; Saunders, Russell W.; Hedin, Jonas; Stegman, Jacek; Khaplanov, Misha; Gumbel, Jörg; Lynch, Kristina A.; Bracikowski, Phillip J.; Gelinas, Lynette J.; Friedrich, Martin; Blindheim, Sandra; Gausa, Michael; Williams, Bifford P.

2014-10-01

The Hotel Payload 2 rocket was launched on January 31st 2008 at 20.14 LT from the Andøya Rocket Range in northern Norway (69.31° N, 16.01° E). Measurements in the 75-105 km region of atomic O, negatively-charged dust, positive ions and electrons with a suite of instruments on the payload were complemented by lidar measurements of atomic Na and temperature from the nearby ALOMAR observatory. The payload passed within 2.58 km of the lidar at an altitude of 90 km. A series of coupled models is used to explore the observations, leading to two significant conclusions. First, the atomic Na layer and the vertical profiles of negatively-charged dust (assumed to be meteoric smoke particles), electrons and positive ions, can be modelled using a self-consistent meteoric input flux. Second, electronic structure calculations and Rice-Ramsperger-Kassel-Markus theory are used to show that even small Fe-Mg-silicates are able to attach electrons rapidly and form stable negatively-charged particles, compared with electron attachment to O2 and O3. This explains the substantial electron depletion between 80 and 90 km, where the presence of atomic O at concentrations in excess of 1010 cm-3 prevents the formation of stable negative ions.

Thermochemistry and kinetics for 2-butanone-1-yl radical (CH2·C(═O)CH2CH3) reactions with O2.

PubMed

Sebbar, N; Bozzelli, J W; Bockhorn, H

2014-01-09

Thermochemistry of reactants, intermediates, transition state structures, and products along with kinetics on the association of CH2·C(═O)CH2CH3 (2-butanone-1-yl) with O2 and dissociation of the peroxy adduct isomers are studied. Thermochemical properties are determined using ab initio (G3MP2B3 and G3) composite methods along with density functional theory (B3LYP/6-311g(d,p)). Entropy and heat capacity contributions versus temperature are determined from structures, vibration frequencies, and internal rotor potentials. The CH2·C(═O)CH2CH3 radical + O2 association results in a chemically activated peroxy radical with 27 kcal mol(-1) excess of energy. The chemically activated adduct can react to stabilized peroxy or hydroperoxide alkyl radical adducts, further react to lactones plus hydroxyl radical, or form olefinic ketones and a hydroperoxy radical. Kinetic parameters are determined from the G3 composite methods derived thermochemical parameters, and quantum Rice-Ramsperger-Kassel (QRRK) analysis to calculate k(E) with master equation analysis to evaluate falloff in the chemically activated and dissociation reactions. One new, not previously reported, peroxy chemistry reaction is presented. It has a low barrier path and involves a concerted reaction resulting in olefin formation, H2O elimination, and an alkoxy radical.

Ab initio kinetics and thermal decomposition mechanism of mononitrobiuret and 1,5-dinitrobiuret

NASA Astrophysics Data System (ADS)

Sun, Hongyan; Vaghjiani, Ghanshyam L.

2015-05-01

Mononitrobiuret (MNB) and 1,5-dinitrobiuret (DNB) are tetrazole-free, nitrogen-rich, energetic compounds. For the first time, a comprehensive ab initio kinetics study on the thermal decomposition mechanisms of MNB and DNB is reported here. In particular, the intramolecular interactions of amine H-atom with electronegative nitro O-atom and carbonyl O-atom have been analyzed for biuret, MNB, and DNB at the M06-2X/aug-cc-pVTZ level of theory. The results show that the MNB and DNB molecules are stabilized through six-member-ring moieties via intramolecular H-bonding with interatomic distances between 1.8 and 2.0 Å, due to electrostatic as well as polarization and dispersion interactions. Furthermore, it was found that the stable molecules in the solid state have the smallest dipole moment amongst all the conformers in the nitrobiuret series of compounds, thus revealing a simple way for evaluating reactivity of fuel conformers. The potential energy surface for thermal decomposition of MNB was characterized by spin restricted coupled cluster theory at the RCCSD(T)/cc-pV∞ Z//M06-2X/aug-cc-pVTZ level. It was found that the thermal decomposition of MNB is initiated by the elimination of HNCO and HNN(O)OH intermediates. Intramolecular transfer of a H-atom, respectively, from the terminal NH2 group to the adjacent carbonyl O-atom via a six-member-ring transition state eliminates HNCO with an energy barrier of 35 kcal/mol and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary process involved in the thermal decomposition of DNB, which processes C2v symmetry. The rate coefficients for the primary decomposition channels for MNB and DNB were quantified as functions of temperature and pressure. In addition, the thermal decomposition of HNN(O)OH was analyzed via Rice-Ramsperger-Kassel-Marcus/multi-well master equation simulations, the results of which reveal the formation of (NO2 + H2O) to be the major decomposition path. Furthermore, we provide fundamental interpretations for the experimental results of Klapötke et al. [Combust. Flame 139, 358-366 (2004)] regarding the thermal stability of MNB and DNB, and their decomposition products. Notably, a fundamental understanding of fuel stability, decomposition mechanism, and key reactions leading to ignition is essential in the design and manipulation of molecular systems for the development of new energetic materials for advanced propulsion applications.

Ab initio kinetics and thermal decomposition mechanism of mononitrobiuret and 1,5-dinitrobiuret.

PubMed

Sun, Hongyan; Vaghjiani, Ghanshyam L

2015-05-28

Mononitrobiuret (MNB) and 1,5-dinitrobiuret (DNB) are tetrazole-free, nitrogen-rich, energetic compounds. For the first time, a comprehensive ab initio kinetics study on the thermal decomposition mechanisms of MNB and DNB is reported here. In particular, the intramolecular interactions of amine H-atom with electronegative nitro O-atom and carbonyl O-atom have been analyzed for biuret, MNB, and DNB at the M06-2X/aug-cc-pVTZ level of theory. The results show that the MNB and DNB molecules are stabilized through six-member-ring moieties via intramolecular H-bonding with interatomic distances between 1.8 and 2.0 Å, due to electrostatic as well as polarization and dispersion interactions. Furthermore, it was found that the stable molecules in the solid state have the smallest dipole moment amongst all the conformers in the nitrobiuret series of compounds, thus revealing a simple way for evaluating reactivity of fuel conformers. The potential energy surface for thermal decomposition of MNB was characterized by spin restricted coupled cluster theory at the RCCSD(T)/cc-pV∞ Z//M06-2X/aug-cc-pVTZ level. It was found that the thermal decomposition of MNB is initiated by the elimination of HNCO and HNN(O)OH intermediates. Intramolecular transfer of a H-atom, respectively, from the terminal NH2 group to the adjacent carbonyl O-atom via a six-member-ring transition state eliminates HNCO with an energy barrier of 35 kcal/mol and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary process involved in the thermal decomposition of DNB, which processes C2v symmetry. The rate coefficients for the primary decomposition channels for MNB and DNB were quantified as functions of temperature and pressure. In addition, the thermal decomposition of HNN(O)OH was analyzed via Rice-Ramsperger-Kassel-Marcus/multi-well master equation simulations, the results of which reveal the formation of (NO2 + H2O) to be the major decomposition path. Furthermore, we provide fundamental interpretations for the experimental results of Klapötke et al. [Combust. Flame 139, 358-366 (2004)] regarding the thermal stability of MNB and DNB, and their decomposition products. Notably, a fundamental understanding of fuel stability, decomposition mechanism, and key reactions leading to ignition is essential in the design and manipulation of molecular systems for the development of new energetic materials for advanced propulsion applications.

Mechanism and kinetics of low-temperature oxidation of a biodiesel surrogate: methyl propanoate radicals with oxygen molecule.

PubMed

Le, Xuan T; Mai, Tam V T; Ratkiewicz, Artur; Huynh, Lam K

2015-04-23

This paper presents a computational study on the low-temperature mechanism and kinetics of the reaction between molecular oxygen and alkyl radicals of methyl propanoate (MP), which plays an important role in low-temperature oxidation and/or autoignition processes of the title fuel. Their multiple reaction pathways either accelerate the oxidation process via chain branching or inhibit it by forming relatively stable products. The potential energy surfaces of the reactions between three primary MP radicals and molecular oxygen, namely, C(•)H2CH2COOCH3 + O2, CH3C(•)HCOOCH3 + O2, and CH3CH2COOC(•)H2 + O2, were constructed using the accurate composite CBS-QB3 method. Thermodynamic properties of all species as well as high-pressure rate constants of all reaction channels were derived with explicit corrections for tunneling and hindered internal rotations. Our calculation results are in good agreement with a limited number of scattered data in the literature. Furthermore, pressure- and temperature-dependent rate constants for all reaction channels on the multiwell-multichannel potential energy surfaces were computed with the quantum Rice-Ramsperger-Kassel (QRRK) and the modified strong collision (MSC) theories. This procedure resulted in a thermodynamically consistent detailed kinetic submechanism for low-temperature oxidation governed by the title process. A simplified mechanism, which consists of important reactions, is also suggested for low-temperature combustion at engine-like conditions.

On the theory of time dilation in chemical kinetics

NASA Astrophysics Data System (ADS)

Baig, Mirza Wasif

2017-10-01

The rates of chemical reactions are not absolute but their magnitude depends upon the relative speeds of the moving observers. This has been proved by unifying basic theories of chemical kinetics, which are transition state theory, collision theory, RRKM and Marcus theory, with the special theory of relativity. Boltzmann constant and energy spacing between permitted quantum levels of molecules are quantum mechanically proved to be Lorentz variant. The relativistic statistical thermodynamics has been developed to explain quasi-equilibrium existing between reactants and activated complex. The newly formulated Lorentz transformation of the rate constant from Arrhenius equation, of the collision frequency and of the Eyring and Marcus equations renders the rate of reaction to be Lorentz variant. For a moving observer moving at fractions of the speed of light along the reaction coordinate, the transition state possess less kinetic energy to sweep translation over it. This results in the slower transformation of reactants into products and in a stretched time frame for the chemical reaction to complete. Lorentz transformation of the half-life equation explains time dilation of the half-life period of chemical reactions and proves special theory of relativity and presents theory in accord with each other. To demonstrate the effectiveness of the present theory, the enzymatic reaction of methylamine dehydrogenase and radioactive disintegration of Astatine into Bismuth are considered as numerical examples.

Kinetic modeling of methyl butanoate in shock tube.

PubMed

Huynh, Lam K; Lin, Kuang C; Violi, Angela

2008-12-25

An increased necessity for energy independence and heightened concern about the effects of rising carbon dioxide levels have intensified the search for renewable fuels that could reduce our current consumption of petrol and diesel. One such fuel is biodiesel, which consists of the methyl esters of fatty acids. Methyl butanoate (MB) contains the essential chemical structure of the long-chain fatty acids and a shorter, but similar, alkyl chain. This paper reports on a detailed kinetic mechanism for MB that is assembled using theoretical approaches. Thirteen pathways that include fuel decomposition, isomerization, and propagation steps were computed using ab initio calculations [J. Org. Chem. 2008, 73, 94]. Rate constants from first principles for important reactions in CO(2) formation, namely CH(3)OCO=CH(3) + CO(2) (R1) and CH(3)OCO=CH(3)O + CO (R2) reactions, are computed at high levels of theory and implemented in the mechanism. Using the G3B3 potential energy surface together with the B3LYP/6-31G(d) gradient, Hessian and geometries, the rate constants for reactions R1 and R2 are calculated using the Rice-Ramsperger-Kassel-Marcus theory with corrections from treatments for tunneling, hindered rotation, and variational effects. The calculated rate constants of reaction R1 differ from the data present in the literature by at most 20%, while those of reaction R2 are about a factor of 4 lower than the available values. The new kinetic model derived from ab initio simulations is combined with the kinetic mechanism presented by Fisher et al. [Proc. Combust. Inst. 2000, 28, 1579] together with the addition of the newly found six-centered unimolecular elimination reaction that yields ethylene and methyl acetate, MB = C(2)H(4) + CH(3)COOCH(3). This latter pathway requires the inclusion of the CH(3)COOCH(3) decomposition model suggested by Westbrook et al. [Proc. Combust. Inst. 2008, accepted]. The newly composed kinetic mechanism for MB is used to study the CO(2) formation during the pyrolysis of MB as well as to investigate the autoignition of MB in a shock tube reactor at different temperatures and pressures. The computed results agree very well with experimental data present in the literature. Sensitivity and flux (rate-of-production) analyses are carried out for the CO(2) formation with the new MB mechanism, together with available reaction mechanisms, to assess the importance of various kinetic pathways for each regime. With the new mechanism, the flux analyses for the formation of C(2)H species, one of the most important species for ignition delay time, are also presented at different conditions. In addition to giving a better chemical insight of the pyrolysis/oxidation of MB, the results suggest ways to improve the mechanism's capability to predict CO(2) formation and ignition delay times in pyrolysis and oxidation conditions.

Ab initio chemical kinetics for the ClOO + NO reaction: Effects of temperature and pressure on product branching formation

NASA Astrophysics Data System (ADS)

Raghunath, P.; Lin, M. C.

2012-07-01

The kinetics and mechanism for the reaction of ClOO with NO have been investigated by ab initio molecular orbital theory calculations based on the CCSD(T)/6-311+G(3df)//PW91PW91/6-311+G(3df) method, employed to evaluate the energetics for the construction of potential energy surfaces and prediction of reaction rate constants. The results show that the reaction can produce two key low energy products ClNO + 3O2 via the direct triplet abstraction path and ClO + NO2 via the association and decomposition mechanism through long-lived singlet pc-ClOONO and ClONO2 intermediates. The yield of ClNO + O2 (1△) from any of the singlet intermediates was found to be negligible because of their high barriers and tight transition states. As both key reactions initially occur barrierlessly, their rate constants were evaluated with a canonical variational approach in our transition state theory and Rice-Ramspergen-Kassel-Marcus/master equation calculations. The rate constants for ClNO + 3O2 and ClO + NO2 production from ClOO + NO can be given by 2.66 × 10-16 T1.91 exp(341/T) (200-700 K) and 1.48 × 10-24 T3.99 exp(1711/T) (200-600 K), respectively, independent of pressure below atmospheric pressure. The predicted total rate constant and the yields of ClNO and NO2 in the temperature range of 200-700 K at 10-760 Torr pressure are in close agreement with available experimental results.

Ab Initio Reaction Kinetics of CH 3 O$$\\dot{C}$$(=O) and $$\\dot{C}$$H 2 OC(=O)H Radicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Ting; Yang, Xueliang; Ju, Yiguang

The dissociation and isomerization kinetics of the methyl ester combustion intermediates methoxycarbonyl radical (CH3Omore » $$\\dot{C}$$(=O)) and (formyloxy)methyl radical ($$\\dot{C}$$H2OC(=O)H) are investigated theoretically using high-level ab initio methods and Rice–Ramsperger–Kassel–Marcus (RRKM)/master equation (ME) theory. Geometries obtained at the hybrid density functional theory (DFT) and coupled cluster singles and doubles with perturbative triples correction (CCSD(T)) levels of theory are found to be similar. We employ high-level ab initio wave function methods to refine the potential energy surface: CCSD(T), multireference singles and doubles configuration interaction (MRSDCI) with the Davidson–Silver (DS) correction, and multireference averaged coupled-pair functional (MRACPF2) theory. MRSDCI+DS and MRACPF2 capture the multiconfigurational character of transition states (TSs) and predict lower barrier heights than CCSD(T). The temperature- and pressure-dependent rate coefficients are computed using RRKM/ME theory in the temperature range 300–2500 K and a pressure range of 0.01 atm to the high-pressure limit, which are then fitted to modified Arrhenius expressions. Dissociation of CH3O$$\\dot{C}$$(=O) to $$\\dot{C}$$H3 and CO2 is predicted to be much faster than dissociating to CH3$$\\dot{O}$$ and CO, consistent with its greater exothermicity. Isomerization between CH3O$$\\dot{C}$$(=O) and $$\\dot{C}$$H2OC(=O)H is predicted to be the slowest among the studied reactions and rarely happens even at high temperature and high pressure, suggesting the decomposition pathways of the two radicals are not strongly coupled. The predicted rate coefficients and branching fractions at finite pressures differ significantly from the corresponding high-pressure-limit results, especially at relatively high temperatures. Finally, because it is one of the most important CH3$$\\dot{O}$$ removal mechanisms under atmospheric conditions, the reaction kinetics of CH3$$\\dot{O}$$ + CO was also studied along the PES of CH3O$$\\dot{C}$$(=O); the resulting kinetics predictions are in remarkable agreement with experiments.« less

Thermochemical and kinetic analysis of the thermal decomposition of monomethylhydrazine: an elementary reaction mechanism.

PubMed

Sun, Hongyan; Law, Chung K

2007-05-17

The reaction kinetics for the thermal decomposition of monomethylhydrazine (MMH) was studied with quantum Rice-Ramsperger-Kassel (QRRK) theory and a master equation analysis for pressure falloff. Thermochemical properties were determined by ab initio and density functional calculations. The entropies, S degrees (298.15 K), and heat capacities, Cp degrees (T) (0 < or = T/K < or = 1500), from vibrational, translational, and external rotational contributions were calculated using statistical mechanics based on the vibrational frequencies and structures obtained from the density functional study. Potential barriers for internal rotations were calculated at the B3LYP/6-311G(d,p) level, and hindered rotational contributions to S degrees (298.15 K) and Cp degrees (T) were calculated by solving the Schrödinger equation with free rotor wave functions, and the partition coefficients were treated by direct integration over energy levels of the internal rotation potentials. Enthalpies of formation, DeltafH degrees (298.15 K), for the parent MMH (CH3NHNH2) and its corresponding radicals CH3N*NH2, CH3NHN*H, and C*H2NHNH2 were determined to be 21.6, 48.5, 51.1, and 62.8 kcal mol(-1) by use of isodesmic reaction analysis and various ab initio methods. The kinetic analysis of the thermal decomposition, abstraction, and substitution reactions of MMH was performed at the CBS-QB3 level, with those of N-N and C-N bond scissions determined by high level CCSD(T)/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) calculations. Rate constants of thermally activated MMH to dissociation products were calculated as functions of pressure and temperature. An elementary reaction mechanism based on the calculated rate constants, thermochemical properties, and literature data was developed to model the experimental data on the overall MMH thermal decomposition rate. The reactions of N-N and C-N bond scission were found to be the major reaction paths for the modeling of MMH homogeneous decomposition at atmospheric conditions.

Vibrational dynamics of aniline(Ar)1 and aniline(CH4)1 clusters

NASA Astrophysics Data System (ADS)

Nimlos, M. R.; Young, M. A.; Bernstein, E. R.; Kelley, D. F.

1989-11-01

The first excited electronic state (S1) vibrational dynamics of aniline(Ar)1 and aniline(CH4)1 van der Waals (vdW) clusters have been studied using molecular jet and time resolved emission spectroscopic techniques. The rates of intramolecular vibrational energy redistribution (IVR) and vibrational predissociation (VP) as functions of vibrational energy are reported for both clusters. For vibrational energy in excess of the cluster binding energy, both clusters are observed to dissociate. The dispersed emission spectra of these clusters demonstrate that aniline(Ar)1 dissociates to all energetically accessible bare molecule states and that aniline(CH4)1 dissociates selectively to only the bare molecule vibrationless state. The emission kinetics show that in the aniline(Ar)1 case, the initially excited states have nanosecond lifetimes, and intermediate cluster states have very short lifetimes. In contrast, the initially excited aniline(CH4)1 states and other intermediate vibrationally excited cluster states are very short lived (<100 ps), and the intermediate cluster 00 state is observed. These results can be understood semiquantitatively in terms of an overall serial IVR/VP mechanism which consists of the following: (1) the rates of chromophore to vdW mode IVR are given by Fermi's golden rule, and the density of vdW vibrational states is the most important factor in determining the relative [aniline(Ar)1 vs aniline(CH4)1] rates of IVR; (2) IVR among the vdW modes is rapid; and (3) VP rates can be calculated by a restricted vdW mode phase space Rice-Ramsberger-Kassel-Marcus theory. Since the density of vdW states is three orders of magnitude greater for aniline(CH4)1 than aniline(Ar)1 at 700 cm-1, the model predicts that IVR is slow and rate limiting in aniline(Ar)1, whereas VP is slow and rate limiting in aniline(CH4)1. The agreement of these predictions with the experimental results is very good and is discussed in detail.

Herbert Marcuse's Critical Theory of the Media.

ERIC Educational Resources Information Center

Daley, Patrick J.

As a member of the Frankfurt School of critical theory, Herbert Marcuse believed that industrial capitalism and the bureaucratization of society stripped humans of any claims to autonomy and undermined their critical expression with a functional language. However, Marcuse did no more than point an inchoate ideological finger at the production side…

Finding Educational Insights in Psychoanalytic Theory with Marcuse and Adorno

ERIC Educational Resources Information Center

Huhtala, Hanna-Maija

2016-01-01

This article seeks to clarify the potential that Herbert Marcuse's and Theodor W. Adorno's psychoanalytic accounts may have with respect to the philosophy of education today. Marcuse and Adorno both share the view that psychoanalytic theory enables a deeper understanding of the social and biological dynamics of consciousness. For both thinkers,…

Memory, Critical Theory and the Argument from History.

ERIC Educational Resources Information Center

Cox, J. Robert

1990-01-01

Explores the function of memory in critical theory, particularly in the work of Herbert Marcuse, as the basis for a critical argumentation. Argues that Marcuse's view suggests that argument is a "re-membering" of what had been split asunder--reason, imagination, and the capacity of action. Discusses other implications of Marcuse's…

Cyclohexane isomerization. Unimolecular dynamics of the twist-boat intermediate.

PubMed

Kakhiani, Khatuna; Lourderaj, Upakarasamy; Hu, Wenfang; Birney, David; Hase, William L

2009-04-23

Direct dynamics simulations were performed at the HF/6-31G level of theory to investigate the intramolecular and unimolecuar dynamics of the twist-boat (TB) intermediate on the cyclohexane potential energy surface (PES). Additional calculations were performed at the MP2/aug-cc-pVDZ level of theory to further characterize the PES's stationary points. The trajectories were initiated at the C(1) and C(2) half-chair transition states (TSs) connecting a chair conformer with a TB intermediate, via an intrinsic reaction coordinate (IRC). Energy was added in accord with a microcanonical ensemble at the average energy for experiments at 263 K. Important nontransition state theory (TST), non-IRC, and non-RRKM dynamics were observed in the simulations. Trajectories initially directed toward the chair conformer had a high probability of recrossing the TS, with approximately 30% forming a TB intermediate instead of accessing the potential energy well for the conformer. The TB intermediate initially formed was not necessarily the one connected to the TS via the IRC. Of the trajectories initiated at the C(2) half-chair TS and initially directed toward the chair conformer, 35% formed a TB intermediate instead of the chair conformer. Also, of the trajectories forming a TB intermediate, only 16% formed the TB intermediate connected with the C(2) TS via the IRC. Up to eight consecutive TB --> TB isomerizations were followed, and non-RRKM behavior was observed in their dynamics. A TB can isomerize to two different TBs, one by a clockwise rotation of C-C-C-C dihedral angles and the other by a counterclockwise rotation. In contrast to RRKM theory, which predicts equivalent probabilities for these rotations, the trajectory dynamics show they are not equivalent and depend on whether the C(1) or C(2) half-chair TS is initially excited. Non-RRKM dynamics is also observed in the isomerization of the TB intermediates to the chair conformers. RRKM theory assumes equivalent probabilities for isomerizing to the two chair conformers. In contrast, for the first and following TB intermediate formed, there is a preference to isomerize to the chair conformer connected to the TS at which the trajectories were initiated. For the first TB intermediate formed, approximately 30% of the isomerization is to a chair conformer, but this fraction decreases for the later formed TB intermediates and becomes approximately 10% for the eighth consecutive TB intermediate formed.

Transition from direct to inverted charge transport Marcus regions in molecular junctions via molecular orbital gating

NASA Astrophysics Data System (ADS)

Yuan, Li; Wang, Lejia; Garrigues, Alvar R.; Jiang, Li; Annadata, Harshini Venkata; Anguera Antonana, Marta; Barco, Enrique; Nijhuis, Christian A.

2018-04-01

Solid-state molecular tunnel junctions are often assumed to operate in the Landauer regime, which describes essentially activationless coherent tunnelling processes. In solution, on the other hand, charge transfer is described by Marcus theory, which accounts for thermally activated processes. In practice, however, thermally activated transport phenomena are frequently observed also in solid-state molecular junctions but remain poorly understood. Here, we show experimentally the transition from the Marcus to the inverted Marcus region in a solid-state molecular tunnel junction by means of intra-molecular orbital gating that can be tuned via the chemical structure of the molecule and applied bias. In the inverted Marcus region, charge transport is incoherent, yet virtually independent of temperature. Our experimental results fit well to a theoretical model that combines Landauer and Marcus theories and may have implications for the interpretation of temperature-dependent charge transport measurements in molecular junctions.

Barrierless association of CF2 and dissociation of C2F4 by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

PubMed Central

Bao, Junwei Lucas; Zhang, Xin

2016-01-01

Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C2F4), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice–Ramsperger–Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements. PMID:27834727

Thermochemical and kinetic analysis on the reactions of O2 with products from OH addition to isobutene, 2-hydroxy-1,1-dimethylethyl, and 2-hydroxy-2-methylpropyl radicals: HO2 formation from oxidation of neopentane, Part II.

PubMed

Sun, Hongyan; Bozzelli, Joseph W; Law, Chung K

2007-06-14

Unimolecular dissociation of a neopentyl radical to isobutene and methyl radical is competitive with the neopentyl association with O2 ((3)Sigma(g)-) in thermal oxidative systems. Furthermore, both isobutene and the OH radical are important primary products from the reactions of neopentyl with O2. Consequently, the reactions of O2 with the 2-hydroxy-1,1-dimethylethyl and 2-hydroxy-2-methylpropyl radicals resulting from the OH addition to isobutene are important to understanding the oxidation of neopentane and other branched hydrocarbons. Reactions that correspond to the association of radical adducts with O2((3)Sigma(g)-) involve chemically activated peroxy intermediates, which can isomerize and react to form one of several products before stabilization. The above reaction systems were analyzed with ab initio and density functional calculations to evaluate the thermochemistry, reaction paths, and kinetics that are important in neopentyl radical oxidation. The stationary points of potential energy surfaces were analyzed based on the enthalpies calculated at the CBS-Q level. The entropies, S(degrees)298, and heat capacities, C(p)(T), (0

Marcus Theory: Thermodynamics CAN Control the Kinetics of Electron Transfer Reactions

ERIC Educational Resources Information Center

Silverstein, Todd P.

2012-01-01

Although it is generally true that thermodynamics do not influence kinetics, this is NOT the case for electron transfer reactions in solution. Marcus Theory explains why this is so, using straightforward physical chemical principles such as transition state theory, Arrhenius' Law, and the Franck-Condon Principle. Here the background and…

Critical Social Theory: A Portrait

ERIC Educational Resources Information Center

Torres, Carlos A.

2012-01-01

The term Critical Social Theory is employed in this article following the tradition of the Frankfurt School, and particularly the work of Herbert Marcuse and his interpretation of the political and social philosophy of Hegel and Marx. Discussing the contribution of G.W.F. Hegel to social theory Marcuse argued that: "Hegel's system brings to a…

Rudolph A. Marcus and His Theory of Electron Transfer Reactions

Science.gov Websites

early 1950s and soon discovered ... a strong experimental program at Brookhaven on electron-transfer experimental work provided the first verification of several of the predictions of his theory. This, in turn Marcus theory, namely, experimental evidence for the so-called "inverted region" where rates

Critical Theory and Information Studies: A Marcusean Infusion

ERIC Educational Resources Information Center

Pyati, Ajit K.

2006-01-01

In the field of library and information science, also known as information studies, critical theory is often not included in debates about the discipline's theoretical foundations. This paper argues that the critical theory of Herbert Marcuse, in particular, has a significant contribution to make to the field of information studies. Marcuse's…

Herbert Marcuse, Grandfather of the New Left.

ERIC Educational Resources Information Center

Bourne, Tom

1979-01-01

A little over ten years ago, Herbert Marcuse found himself in the cross fire of the student movement. The radical right saw in Marcuse an incitement to revolutionary action, but individualism distinguished him from doctrinaire Marxists. He upheld the importance of pure contemplation and theory. (MLW)

Marcus-Hush-Chidsey theory of electron transfer to and from species bound at a non-uniform electrode surface: Theory and experiment

NASA Astrophysics Data System (ADS)

Henstridge, Martin C.; Batchelor-McAuley, Christopher; Gusmão, Rui; Compton, Richard G.

2011-11-01

Two simple models of electrode surface inhomogeneity based on Marcus-Hush theory are considered; a distribution in formal potentials and a distribution in electron tunnelling distances. Cyclic voltammetry simulated using these models is compared with that simulated using Marcus-Hush theory for a flat, uniform and homogeneous electrode surface, with the two models of surface inhomogeneity yielding broadened peaks with decreased peak-currents. An edge-plane pyrolytic graphite electrode is covalently modified with ferrocene via 'click' chemistry and the resulting voltammetry compared with each of the three previously considered models. The distribution of formal potentials is seen to fit the experimental data most closely.

Analysis of S2QA- charge recombination with the Arrhenius, Eyring and Marcus theories.

PubMed

Rantamäki, Susanne; Tyystjärvi, Esa

2011-01-01

The Q band of photosynthetic thermoluminescence, measured in the presence of a herbicide that blocks electron transfer from PSII, is associated with recombination of the S(2)Q(A)(-) charge pair. The same charge recombination reaction can be monitored with chlorophyll fluorescence. It has been shown that the recombination occurs via three competing routes of which one produces luminescence. In the present study, we measured the thermoluminescence Q band and the decay of chlorophyll fluorescence yield after a single turnover flash at different temperatures from spinach thylakoids. The data were analyzed using the commonly used Arrhenius theory, the Eyring rate theory and the Marcus theory of electron transfer. The fitting error was minimized for both thermoluminescence and fluorescence by adjusting the global, phenomenological constants obtained when the reaction rate theories were applied to the multi-step recombination reaction. For chlorophyll fluorescence, all three theories give decent fits. The peak position of the thermoluminescence Q band is correct by all theories but the form of the Q band is somewhat different in curves predicted by the three theories. The Eyring and Marcus theories give good fits for the decreasing part of the thermoluminescence curve and Marcus theory gives the closest fit for the rising part. Copyright © 2011 Elsevier B.V. All rights reserved.

Thermal decomposition of pyrazole to vinylcarbene + N 2: A first principles/RRKM study

NASA Astrophysics Data System (ADS)

da Silva, Gabriel

2009-05-01

Thermal decomposition of pyrazole, a five-membered nitrogen-containing heterocycle, has been studied using ab initio G3X theory and RRKM rate theory. The decomposition mechanism involves an intramolecular hydrogen shift to 3 H-pyrazole, followed by ring opening to 3-diazo-1-propene and dissociation to vinylcarbene (CH 2CHCH) + N 2. At 1 atm the calculated rate equation k [s -1] = 1.26 × 10 50T-10.699e -41200/T is obtained, which agrees with the results of flash vacuum pyrolysis experiments. The pyrazole decomposition product vinylcarbene is expected to rearrange to propyne, making pyrazole decomposition essentially thermoneutral. It is hypothesized that at high concentrations vinylcarbene could undergo a self-reaction to 1,3- and 1,4-cyclohexadiene.

Marcus equation

DOE R&D Accomplishments Database

1998-09-21

In the late 1950s to early 1960s Rudolph A. Marcus developed a theory for treating the rates of outer-sphere electron-transfer reactions. Outer-sphere reactions are reactions in which an electron is transferred from a donor to an acceptor without any chemical bonds being made or broken. (Electron-transfer reactions in which bonds are made or broken are referred to as inner-sphere reactions.) Marcus derived several very useful expressions, one of which has come to be known as the Marcus cross-relation or, more simply, as the Marcus equation. It is widely used for correlating and predicting electron-transfer rates. For his contributions to the understanding of electron-transfer reactions, Marcus received the 1992 Nobel Prize in Chemistry. This paper discusses the development and use of the Marcus equation. Topics include self-exchange reactions; net electron-transfer reactions; Marcus cross-relation; and proton, hydride, atom and group transfers.

On the relation between Marcus theory and ultrafast spectroscopy of solvation kinetics

NASA Astrophysics Data System (ADS)

Roy, Santanu; Galib, Mirza; Schenter, Gregory K.; Mundy, Christopher J.

2018-01-01

The phenomena of solvent exchange control the process of solvating ions, protons, and charged molecules. Building upon our extension of Marcus' philosophy of electron transfer, we provide a new perspective of ultrafast solvent exchange mechanism around ions measurable by two-dimensional infrared (2DIR) spectroscopy. In this theory, solvent rearrangement drives an ion-bound water to an activated state of higher coordination number, triggering ion-water separation that leads to the solvent-bound state of the water molecule. This ion-bound to solvent-bound transition rate for a BF4--water system is computed using ab initio molecular dynamics and Marcus theory, and is found to be in excellent agreement with the 2DIR measurement.

Groundwork for the Concept of Technique in Education: Herbert Marcuse and Technological Society

ERIC Educational Resources Information Center

Pierce, Clayton

2006-01-01

This article articulates the groundwork for a new understanding of the concept of technique through a critical engagement with Herbert Marcuse's critical theory of technology. To this end, it identifies and engages three expressions of technique in Marcuse's work: mimesis, reified labor, and the happy consciousness. It is argued that this mapping…

Perspective: chemical dynamics simulations of non-statistical reaction dynamics

PubMed Central

Ma, Xinyou; Hase, William L.

2017-01-01

Non-statistical chemical dynamics are exemplified by disagreements with the transition state (TS), RRKM and phase space theories of chemical kinetics and dynamics. The intrinsic reaction coordinate (IRC) is often used for the former two theories, and non-statistical dynamics arising from non-IRC dynamics are often important. In this perspective, non-statistical dynamics are discussed for chemical reactions, with results primarily obtained from chemical dynamics simulations and to a lesser extent from experiment. The non-statistical dynamical properties discussed are: post-TS dynamics, including potential energy surface bifurcations, product energy partitioning in unimolecular dissociation and avoiding exit-channel potential energy minima; non-RRKM unimolecular decomposition; non-IRC dynamics; direct mechanisms for bimolecular reactions with pre- and/or post-reaction potential energy minima; non-TS theory barrier recrossings; and roaming dynamics. This article is part of the themed issue ‘Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces’. PMID:28320906

Zero-Point Energy Constraint for Unimolecular Dissociation Reactions. Giving Trajectories Multiple Chances To Dissociate Correctly.

PubMed

Paul, Amit K; Hase, William L

2016-01-28

A zero-point energy (ZPE) constraint model is proposed for classical trajectory simulations of unimolecular decomposition and applied to CH4* → H + CH3 decomposition. With this model trajectories are not allowed to dissociate unless they have ZPE in the CH3 product. If not, they are returned to the CH4* region of phase space and, if necessary, given additional opportunities to dissociate with ZPE. The lifetime for dissociation of an individual trajectory is the time it takes to dissociate with ZPE in CH3, including multiple possible returns to CH4*. With this ZPE constraint the dissociation of CH4* is exponential in time as expected for intrinsic RRKM dynamics and the resulting rate constant is in good agreement with the harmonic quantum value of RRKM theory. In contrast, a model that discards trajectories without ZPE in the reaction products gives a CH4* → H + CH3 rate constant that agrees with the classical and not quantum RRKM value. The rate constant for the purely classical simulation indicates that anharmonicity may be important and the rate constant from the ZPE constrained classical trajectory simulation may not represent the complete anharmonicity of the RRKM quantum dynamics. The ZPE constraint model proposed here is compared with previous models for restricting ZPE flow in intramolecular dynamics, and connecting product and reactant/product quantum energy levels in chemical dynamics simulations.

A new sexual revolution? Critical theory, pornography, and the Internet.

PubMed

Garlick, Steve

2011-08-01

The "sexual revolution" was a central element of North American culture in the 1960s. Today, sex is increasingly central to mainstream culture, in large part due to the Internet, and we might wonder whether we are living through a comparable period of sexual history. In this article, I revisit the work of Herbert Marcuse-the original theorist of the sexual revolution-to ask whether it can contribute to a critical theory of sexuality in the era of digital technology. After outlining Marcuse's theory of the role of Eros in social life, I discuss two pornographic Web sites that combine eroticism and social critique. I argue that Marcuse's work is valuable for its emphasis on the intersection of sex, technology, and capitalist economy, but that it needs to be supplemented by a focus on masculinity and the male body in Internet pornography.

A RRKM study and a DFT assessment on gas-phase fragmentation of formamide-M(2+) (M = Ca, Sr).

PubMed

Martín-Sómer, Ana; Gaigeot, Marie-Pierre; Yáñez, Manuel; Spezia, Riccardo

2014-07-28

A kinetic study of the unimolecular reactivity of formamide-M(2+) (M = Ca, Sr) systems was carried out by means of RRKM statistical theory using high-level DFT. The results predict M(2+), [M(NH2)](+) and [HCO](+) as the main products, together with an intermediate that could eventually evolve to produce [M(NH3)](2+) and CO, for high values of internal energy. In this framework, we also evaluated the influence of the external rotational energy on the reaction rate constants. In order to find a method to perform reliable electronic structure calculations for formamide-M(2+) (M = Ca, Sr) at a relatively low computational cost, an assessment of different methods was performed. In the first assessment twenty-one functionals, belonging to different DFT categories, and an MP2 wave function method using a small basis set were evaluated. CCSD(T)/cc-pWCVTZ single point calculations were used as reference. A second assessment has been performed on geometries and energies. We found BLYP/6-31G(d) and G96LYP/6-31+G(d,p) as the best performing methods, for formamide-Ca(2+) and formamide-Sr(2+), respectively. Furthermore, a detailed assessment was done on RRKM reactivity and G96LYP/6-31G(d) provided results in agreement with higher level calculations. The combination of geometrical, energetics and kinetics (RRKM) criteria to evaluate DFT functionals is rather unusual and provides an original assessment procedure. Overall, we suggest using G96LYP as the best performing functional with a small basis set for both systems.

First-principles calculation of photo-induced electron transfer rate constants in phthalocyanine-C60 organic photovoltaic materials: Beyond Marcus theory

NASA Astrophysics Data System (ADS)

Lee, Myeong H.; Dunietz, Barry D.; Geva, Eitan

2014-03-01

Classical Marcus theory is commonly adopted in solvent-mediated charge transfer (CT) process to obtain the CT rate constant, but it can become questionable when the intramolecular vibrational modes dominate the CT process as in OPV devices because Marcus theory treats these modes classically and therefore nuclear tunneling is not accounted for. We present a computational scheme to obtain the electron transfer rate constant beyond classical Marcus theory. Within this approach, the nuclear vibrational modes are treated quantum-mechanically and a short-time approximation is avoided. Ab initio calculations are used to obtain the basic parameters needed for calculating the electron transfer rate constant. We apply our methodology to phthalocyanine(H2PC)-C60 organic photovoltaic system where one C60 acceptor and one or two H2PC donors are included to model the donor-acceptor interface configuration. We obtain the electron transfer and recombination rate constants for all accessible charge transfer (CT) states, from which the CT exciton dynamics is determined by employing a master equation. The role of higher lying excited states in CT exciton dynamics is discussed. This work is pursued as part of the Center for Solar and Thermal Energy Conversion, an Energy Frontier Research Center funded by the US Department of Energy Office of Science, Office of Basic Energy Sciences under 390 Award No. DE-SC0000957.

One-Dimensionality and Whiteness

ERIC Educational Resources Information Center

Calderon, Dolores

2006-01-01

This article is a theoretical discussion that links Marcuse's concept of one-dimensional society and the Great Refusal with critical race theory in order to achieve a more robust interrogation of whiteness. The author argues that in the context of the United States, the one-dimensionality that Marcuse condemns in "One-Dimensional Man" is best…

Quantitative weaknesses of the Marcus-Hush theory of electrode kinetics revealed by Reverse Scan Square Wave Voltammetry: The reduction of 2-methyl-2-nitropropane at mercury microelectrodes

NASA Astrophysics Data System (ADS)

Laborda, Eduardo; Wang, Yijun; Henstridge, Martin C.; Martínez-Ortiz, Francisco; Molina, Angela; Compton, Richard G.

2011-08-01

The Marcus-Hush and Butler-Volmer kinetic electrode models are compared experimentally by studying the reduction of 2-methyl-2-nitropropane in acetonitrile at mercury microelectrodes using Reverse Scan Square Wave Voltammetry. This technique is found to be very sensitive to the electrode kinetics and to permit critical comparison of the two models. The Butler-Volmer model satisfactorily fits the experimental data whereas Marcus-Hush does not quantitatively describe this redox system.

Surface hopping with a manifold of electronic states. III. Transients, broadening, and the Marcus picture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, Wenjie; Subotnik, Joseph E.; Nitzan, Abraham

2015-06-21

In a previous paper [Dou et al., J. Chem. Phys. 142, 084110 (2015)], we have introduced a surface hopping (SH) approach to deal with the Anderson-Holstein model. Here, we address some interesting aspects that have not been discussed previously, including transient phenomena and extensions to arbitrary impurity-bath couplings. In particular, in this paper we show that the SH approach captures phonon coherence beyond the secular approximation, and that SH rates agree with Marcus theory at steady state. Finally, we show that, in cases where the electronic tunneling rate depends on nuclear position, a straightforward use of Marcus theory rates yieldsmore » a useful starting point for capturing level broadening. For a simple such model, we find I-V curves that exhibit negative differential resistance.« less

Marcus Theory of Ion-Pairing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Santanu; Baer, Marcel D.; Mundy, Christopher J.

We present a theory for ion pair dissociation and association, motivated by the concepts of the Marcus theory of electron transfer. Despite the extensive research on ion-pairing in many chemical and biological processes, much can be learned from the exploration of collective reaction coordinates. To this end, we explore two reaction coordinates, ion pair distance and coordination number. The study of the correlation between these reaction coordinates provides a new insight into the mechanism and kinetics of ion pair dissociation and association in water. The potential of mean force on these 2D-surfaces computed from molecular dynamics simulations of different monovalentmore » ion pairs reveal a Marcus-like mechanism for ion-pairing: Water molecules rearrange forming an activated coordination state prior to ion pair dissociation or association, followed by relaxation of the coordination state due to further water rearrangement. Like Marcus theory, we find the existence of an inverted region where the transition rates are slower with increasing exergonicity. This study provides a new perspective for the future investigations of ion-pairing and transport. SR, CJM, and GKS were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. MDB was supported by MS3 (Materials Synthesis and Simulation Across Scales) Initiative, a Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory (PNNL). The research was performed using PNNL Institutional Computing. PNNL is a multi-program national laboratory operated by Battelle for the U.S. Department of Energy.« less

Ab initio and RRKM study of the reaction of ClO with HOCO radicals.

PubMed

Yu, Hua-Gen; Francisco, Joseph S

2009-11-19

The reaction pathways for the ClO + HOCO reaction have been explored using the coupled-cluster method to locate and optimize the critical points on the ground-state potential-energy surface. Results show that the ClO + HOCO reaction can produce Cl + HOC(O)O, HOCl + CO(2), HCl + CO(3), and HClO + CO(2) via an addition or a direct hydrogen abstraction reaction mechanism. The reaction kinetics has been studied using the variational RRKM theory. It is found that the ClO + HOCO reaction is fast and has a negative temperature dependence at low temperatures. At room temperature, the thermal rate coefficient is obtained as 4.26 x 10(-12) cm(3) molecules(-1) s(-1) with product branching fractions of Cl (0.518), HOCl (0.469), HCl (0.01), and HClO (0.003) at zero pressure. The Cl + HOC(O)O products are major, compared to the HOCl + CO(2) products, because of the loose transition state along the dissociation pathway to eliminate Cl. In addition, the RRKM/master equation simulations indicate that the stabilization of the HOC(O)OCl intermediates is noticeable at moderate pressures as its thermal rate constants reach about 6.0 x 10(-13) cm(3) molecules(-1) s(-1). In contrast, the other product branching ratios for the ClO + HOCO reaction are weakly dependent on pressure.

Atmospheric oxidation mechanism of chlorobenzene.

PubMed

Wu, Runrun; Wang, Sainan; Wang, Liming

2014-09-01

The atmospheric oxidation mechanism of chlorobenzene (CB) initiated by the OH radicals is investigated at M06-2X/6-311++G(2df, 2p) and ROCBS-QB3 levels. The oxidation is initiated by OH addition to the ortho (∼50%), para (∼33%) and meta (∼17%) positions, forming CB-OH adducts as R2, R3, and R4; while the ipso-addition is negligible (∼0.2%). The reactions of the CB-OH adducts with the atmospheric oxygen are further investigated in detail by coupling the unimolecular reaction rate theory calculations with master-equation (RRKM-ME). The CB-OH adducts react with O2 either by irreversible H-abstraction to form chlorophenol and HO2 or by reversible additions to form CB-OH-O2 radicals, which subsequently cyclize to bicyclic radicals. RRKM-ME calculations show that the addition reactions of CB-OH and O2 at the atmospheric pressure are close to but not yet reach their high-pressure-limits. The RRKM-ME simulations predict the yields of 93%, 38%, and 74% for ortho-, meta- and para-chlorophenols from the reactions of O2 with R2, R3 and R4, being lower than their high-pressure-limit yields of 95%, 48%, an 80%, respectively. Overall, the yield of chlorophenols is determined as 72% at the atmospheric pressure. Copyright © 2014 Elsevier Ltd. All rights reserved.

On the relation between Marcus theory and ultrafast spectroscopy of solvation kinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Santanu; Galib, Mirza; Schenter, Gregory K.

The phenomena of solvent exchange control the process of solvating ions, protons, and charged molecules. Building upon our extension of Marcus’ philosophy of electron transfer, here we provide a new perspective of ultrafast solvent exchange mechanism around ions measurable by two-dimensional infrared (2DIR) spectroscopy. In this theory, solvent rearrangement drives an ion-bound water to an activated state of higher coordination number, triggering ion-water separation that leads to the solvent-bound state of the water molecule. This ion-bound to solvent-bound transition rate for a BF 4 --water system is then computed using ab initio molecular dynamics and Marcus theory, and is foundmore » to be in excellent agreement with the 2DIR measurement.« less

On the relation between Marcus theory and ultrafast spectroscopy of solvation kinetics

DOE PAGES

Roy, Santanu; Galib, Mirza; Schenter, Gregory K.; ...

2017-12-24

The phenomena of solvent exchange control the process of solvating ions, protons, and charged molecules. Building upon our extension of Marcus’ philosophy of electron transfer, here we provide a new perspective of ultrafast solvent exchange mechanism around ions measurable by two-dimensional infrared (2DIR) spectroscopy. In this theory, solvent rearrangement drives an ion-bound water to an activated state of higher coordination number, triggering ion-water separation that leads to the solvent-bound state of the water molecule. This ion-bound to solvent-bound transition rate for a BF 4 --water system is then computed using ab initio molecular dynamics and Marcus theory, and is foundmore » to be in excellent agreement with the 2DIR measurement.« less

On the relation between Marcus theory and ultrafast spectroscopy of solvation kinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Santanu; Galib, Mirza; Schenter, Gregory K.

The phenomena of solvent exchange control the process of solvating ions, protons, and charged molecules. Building upon our extension of Marcus’ philosophy of electron transfer, we provide a new perspective of ultrafast solvent exchange mechanism around ions measurable by two-dimensional infrared (2DIR) spectroscopy. In this theory, solvent rearrangement drives an ion-bound water to an activated state of higher coordination number, triggering ion-water separation that leads to the solvent-bound state of the water molecule. This ion-bound to solvent-bound transition rate for a BF4- water system is computed using ab initio molecular dynamics and Marcus theory, and is found to be inmore » excellent agreement with the 2DIR measurement.« less

Marcus Bell-Shaped Electron Transfer Kinetics Observed in an Arrhenius Plot.

PubMed

Waskasi, Morteza M; Kodis, Gerdenis; Moore, Ana L; Moore, Thomas A; Gust, Devens; Matyushov, Dmitry V

2016-07-27

The Marcus theory of electron transfer predicts a bell-shaped dependence of the reaction rate on the reaction free energy. The top of the "inverted parabola" corresponds to zero activation barrier when the electron-transfer reorganization energy and the reaction free energy add up to zero. Although this point has traditionally been reached by altering the chemical structures of donors and acceptors, the theory suggests that it can also be reached by varying other parameters of the system including temperature. We find here dramatic evidence of this phenomenon from experiments on a fullerene-porphyrin dyad. Following photoinduced electron transfer, the rate of charge recombination shows a bell-shaped dependence on the inverse temperature, first increasing with cooling and then decreasing at still lower temperatures. This non-Arrhenius rate law is a result of a strong, approximately hyperbolic temperature variation of the reorganization energy and the reaction free energy. Our results provide potentially the cleanest confirmation of the Marcus energy gap law so far since no modification of the chemical structure is involved.

Hyperbolic metamaterial nanostructures to tune charge-transfer dynamics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, Kwang Jin; Xiao, Yiming; Woo, Jae Heun; Kim, Eun Sun; Kreher, David; Attias, André-Jean; Mathevet, Fabrice; Ribierre, Jean-Charles; Wu, Jeong Weon; André, Pascal

2016-09-01

Charge transfer (CT) is an essential phenomenon relevant to numerous fields including biology, physics and chemistry.1-5 Here, we demonstrate that multi-layered hyperbolic metamaterial (HMM) substrates alter organic semiconductor CT dynamics.6 With triphenylene:perylene diimide dyad supramolecular self-assemblies prepared on HMM substrates, we show that both charge separation (CS) and charge recombination (CR) characteristic times are increased by factors of 2.5 and 1.6, respectively, resulting in longer-lived CT states. We successfully rationalize the experimental data by extending Marcus theory framework with dipole image interactions tuning the driving force. The number of metal-dielectric pairs alters the HMM interfacial effective dielectric constant and becomes a solid analogue to solvent polarizability. Based on the experimental results and extended Marcus theory framework, we find that CS and CR processes are located in normal and inverted regions on Marcus parabola diagram, respectively. The model and further PH3T:PCBM data show that the phenomenon is general and that molecular and substrate engineering offer a wide range of kinetic tailoring opportunities. This work opens the path toward novel artificial substrates designed to control CT dynamics with potential applications in fields including optoelectronics, organic solar cells and chemistry. 1. Marcus, Rev. Mod. Phys., 1993, 65, 599. 2. Marcus, Phys. Chem. Chem. Phys., 2012, 14, 13729. 3. Lambert, et al., Nat. Phys., 2012, 9, 10. 4. C. Clavero, Nat. Photon., 2014, 8, 95. 5. A. Canaguier-Durand, et al., Angew. Chem. Int. Ed., 2013, 52, 10533. 6. K. J. Lee, et al., Submitted, 2015, arxiv.org/abs/1510.08574.

Variational RRKM theory calculation of thermal rate constant for carbon—hydrogen bond fission reaction of nitro benzene

NASA Astrophysics Data System (ADS)

Manesh, Afshin Taghva; Heidarnezhad, Zabi alah; Masnabadi, Nasrin

2013-07-01

The present work provides quantitative results for the rate of unimolecular carbon-hydrogen bond fission reaction of benzene and nitro benzene at elevated temperatures up to 2000 K. The potential energy surface for each C-H (in the ortho, meta, and para sites) bond fission reaction of nitro benzene was investigated by ab initio calculations. The geometry and vibrational frequencies of the species involved in this process were optimized at the MP2 level of theory, using the cc-pvdz basis set. Since C-H bond fission channel is barrier less reaction, we have used variational RRKM theory to predict rate constants. By means of calculated rate constant at the different temperatures, the activation energy and exponential factor were determined. The Arrhenius expression for C-H bond fission reaction of nitro benzene on the ortho, meta and para sites are k( T) = 2.1 × 1017exp(-56575.98/ T), k( T) = 2.1 × 1017exp(-57587.45/ T), and k( T) = 3.3 × 1016exp(-57594.79/ T) respectively. The Arrhenius expression for C-H bond fission reaction of benzene is k( T) = 2 × 1018exp(-59343.48.18/ T). The effect of NO2 group, location of hydrogen atoms on the substituted benzene ring, reaction degeneracy, benzene ring resonance and tunneling effect on the rate expression have been discussed.

Ab Initio Analysis of Auger-Assisted Electron Transfer.

PubMed

Hyeon-Deuk, Kim; Kim, Joonghan; Prezhdo, Oleg V

2015-01-15

Quantum confinement in nanoscale materials allows Auger-type electron-hole energy exchange. We show by direct time-domain atomistic simulation and analytic theory that Auger processes give rise to a new mechanism of charge transfer (CT) on the nanoscale. Auger-assisted CT eliminates the renown Marcus inverted regime, rationalizing recent experiments on CT from quantum dots to molecular adsorbates. The ab initio simulation reveals a complex interplay of the electron-hole and charge-phonon channels of energy exchange, demonstrating a variety of CT scenarios. The developed Marcus rate theory for Auger-assisted CT describes, without adjustable parameters, the experimental plateau of the CT rate in the region of large donor-acceptor energy gap. The analytic theory and atomistic insights apply broadly to charge and energy transfer in nanoscale systems.

The Landgrave in Kassel and Tycho Brahe on Hven

NASA Astrophysics Data System (ADS)

Høg, E.

2018-01-01

Tycho Brahe is known as the greatest astronomer of his time and his observations had great significance for the development of science. Tycho received in 1576 the island Hven not far from Copenhagen as a gift from the Danish king Frederik II and he worked there with many collaborators during twenty years. But Tycho must share the credit for renewing astronomy with Landgrave Wilhelm IV in Kassel as has been better recognized recently. About 1566 Wilhelm achieved a better accuracy of star positions than any astronomer before. Twenty years later, an accuracy about one minute of arc was obtained in Kassel, and soon after also by Tycho Brahe. We shall follow this evolution and the mutual process of learning between Kassel and Hven - which was not without drama. %ZHamel, J., Rothenberg, E., & von Mackensen, L. 1998, AcHA, 2, 1 Høg, E. 2018, RMxAC, 50, 1

MD studies of electron transfer at ambient and elevated pressures

NASA Astrophysics Data System (ADS)

Giles, Alex; Spooner, Jacob; Weinberg, Noham

2013-06-01

The effect of pressure on the rate constants of outer-sphere electron transfer reactions has often been described using the Marcus-Hush theory. This theory agrees well with experiment when internal reorganization of the ionic system is negligible, however it does not offer a recipe for calculation of the effects that result from significant solute restructuring. We have recently developed a molecular dynamics technique that accurately describes structural dependence of molecular volumes in non-polar and weakly polar systems. We are now extending this approach to the case of highly polar ionic systems where both solvent and solute restructuring components are important. For this purpose we construct pressure-dependent two-dimensional surfaces for electron transfer reactions in coordinate system composed of interionic distance and Marcus-type solvent polarization coordinate, and use these surfaces to describe pressure effects on reaction kinetics. R.A. Marcus. J. Chem. Phys. 24, 966 (1956); 24, 979 (1956); 26, 867 (1957). Discuss. Faraday Soc. 29, 21 (1960). Faraday Discuss. Chem. Soc. 74, 7 (1982); N.S. Hush. Trans. Faraday Soc. 57, 557 (1961).

Racism and Surplus Repression.

ERIC Educational Resources Information Center

Johnson, Howard

1983-01-01

Explores the relationship between Herbert Marcuse's theory of "surplus repression" and Freud's theory of the "unconscious" with respect to latent, hidden, covert, or subliminal aspects of racism in the United States. Argues that unconscious racism, manifested in evasion/avoidance, acting out/projection, and attempted…

Tunneling and reflection in unimolecular reaction kinetic energy release distributions

NASA Astrophysics Data System (ADS)

Hansen, K.

2018-02-01

The kinetic energy release distributions in unimolecular reactions is calculated with detailed balance theory, taking into account the tunneling and the reflection coefficient in three different types of transition states; (i) a saddle point corresponding to a standard RRKM-type theory, (ii) an attachment Langevin cross section, and (iii) an absorbing sphere potential at short range, without long range interactions. Corrections are significant in the one dimensional saddle point states. Very light and lightly bound absorbing systems will show measurable effects in decays from the absorbing sphere, whereas the Langevin cross section is essentially unchanged.

Charge-transfer mechanism for electrophilic aromatic nitration and nitrosation via the convergence of (ab initio) molecular-orbital and Marcus-Hush theories with experiments.

PubMed

Gwaltney, Steven R; Rosokha, Sergiy V; Head-Gordon, Martin; Kochi, Jay K

2003-03-19

The highly disparate rates of aromatic nitrosation and nitration, despite the very similar (electrophilic) properties of the active species: NO(+) and NO(2)(+) in Chart 1, are quantitatively reconciled. First, the thorough mappings of the potential-energy surfaces by high level (ab initio) molecular-orbital methodologies involving extensive coupled-cluster CCSD(T)/6-31G optimizations establish the intervention of two reactive intermediates in nitration (Figure 8) but only one in nitrosation (Figure 7). Second, the same distinctive topologies involving double and single potential-energy minima (Figures 6 and 5) also emerge from the semiquantitative application of the Marcus-Hush theory to the transient spectral data. Such a striking convergence from quite different theoretical approaches indicates that the molecular-orbital and Marcus-Hush (potential-energy) surfaces are conceptually interchangeable. In the resultant charge-transfer mechanism, the bimolecular interactions of arene donors with both NO(+) and NO(2)(+) spontaneously lead (barrierless) to pi-complexes in which electron transfer is concurrent with complexation. Such a pi-complex in nitration is rapidly converted to the sigma-complex, whereas this Wheland adduct in nitrosation merely represents a high energy (transition-state) structure. Marcus-Hush analysis thus demonstrates how the strongly differentiated (arene) reactivities toward NO(+) and NO(2)(+) can actually be exploited in the quantitative development of a single coherent (electron-transfer) mechanism for both aromatic nitrosation and nitration.

Predicting Accurate Electronic Excitation Transfer Rates via Marcus Theory with Boys or Edmiston-Ruedenberg Localized Diabatization †

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subotnik, Joseph E.; Vura-Weis, Josh; Sodt, Alex J.

We model the triplet-triplet energy-transfer experiments from the Closs group [Closs, G. L.; et al. J. Am. Chem. Soc. 1988, 110, 2652.] using a combination of Marcus theory and either Boys or Edmiston-Ruedenberg localized diabatization, and we show that relative and absolute rates of electronic excitation transfer may be computed successfully. For the case where both the donor and acceptor occupy equatorial positions on a rigid cyclohexane bridge, we find βcalc = 2.8 per C-C bond, compared with the experimental value βexp = 2.6. This work highlights the power of using localized diabatization methods as a tool for modeling nonequilibriummore » processes.« less

Predicting Accurate Electronic Excitation Transfer Rates via Marcus Theory with Boys or Edmiston-Ruedenberg Localized Diabatization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subotnik, Joseph E.; Vura-Weis, Josh; Sodt, Alex J.

We model the triplet-triplet energy-transfer experiments from the Closs group [Closs, G. L.; et al. J. Am. Chem. Soc. 1988, 110, 2652.] using a combination of Marcus theory and either Boys or Edmiston-Ruedenberg localized diabatization, and we show that relative and absolute rates of electronic excitation transfer may be computed successfully. For the case where both the donor and acceptor occupy equatorial positions on a rigid cyclohexane bridge, we find β calc = 2.8 per C-C bond, compared with the experimental value β exp = 2.6. This work highlights the power of using localized diabatization methods as a tool formore » modeling nonequilibrium processes.« less

Large impact of reorganization energy on photovoltaic conversion due to interfacial charge-transfer transitions.

PubMed

Fujisawa, Jun-ichi

2015-05-14

Interfacial charge-transfer (ICT) transitions are expected to be a novel charge-separation mechanism for efficient photovoltaic conversion featuring one-step charge separation without energy loss. Photovoltaic conversion due to ICT transitions has been investigated using several TiO2-organic hybrid materials that show organic-to-inorganic ICT transitions in the visible region. In applications of ICT transitions to photovoltaic conversion, there is a significant problem that rapid carrier recombination is caused by organic-inorganic electronic coupling that is necessary for the ICT transitions. In order to solve this problem, in this work, I have theoretically studied light-to-current conversions due to the ICT transitions on the basis of the Marcus theory with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. An apparent correlation between the reported incident photon-to-current conversion efficiencies (IPCE) and calculated reorganization energies was clearly found, in which the IPCE increases with decreasing the reorganization energy consistent with the Marcus theory in the inverted region. This activation-energy dependence was systematically explained by the equation formulated by the Marcus theory based on a simple excited-state kinetic scheme. This result indicates that the reduction of the reorganization energy can suppress the carrier recombination and enhance the IPCE. The reorganization energy is predominantly governed by the structural change in the chemical-adsorption moiety between the ground and ICT excited states. This work provides crucial knowledge for efficient photovoltaic conversion due to ICT transitions.

Marine Communications in Desert Shield and Desert Storm

DTIC Science & Technology

1991-01-01

October, and within a matter of days it was operating as intended. Serviced by a crew of 14 Marines, the system enabled much of the previously exported ...establish communications. With this critical component out of order, Colonel Ramsperger and Major Linder retraced their steps in a single HMMWV all the...Ramsperger, LtCol Nicholas C. Petronzio, and Maj Fredrick H. Linder (Author’s Files, MCHC, Washington, D.C.), hereafter 2d MarDiv G-6 notes. 129. Maj

Effects of tunnelling and asymmetry for system-bath models of electron transfer

NASA Astrophysics Data System (ADS)

Mattiat, Johann; Richardson, Jeremy O.

2018-03-01

We apply the newly derived nonadiabatic golden-rule instanton theory to asymmetric models describing electron-transfer in solution. The models go beyond the usual spin-boson description and have anharmonic free-energy surfaces with different values for the reactant and product reorganization energies. The instanton method gives an excellent description of the behaviour of the rate constant with respect to asymmetry for the whole range studied. We derive a general formula for an asymmetric version of the Marcus theory based on the classical limit of the instanton and find that this gives significant corrections to the standard Marcus theory. A scheme is given to compute this rate based only on equilibrium simulations. We also compare the rate constants obtained by the instanton method with its classical limit to study the effect of tunnelling and other quantum nuclear effects. These quantum effects can increase the rate constant by orders of magnitude.

Blinking suppression of CdTe quantum dots on epitaxial graphene and the analysis with Marcus electron transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirose, Takuya; Tamai, Naoto, E-mail: tamai@kwansei.ac.jp; Kutsuma, Yasunori

We have prepared epitaxial graphene by a Si sublimation method from 4H-SiC. Single-particle spectroscopy of CdTe quantum dots (QDs) on epitaxial graphene covered with polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG) showed the suppression of luminescence blinking and ∼10 times decreased luminescence intensity as compared with those on a glass. The electronic coupling constant, H{sub 01}, between CdTe QDs and graphene was calculated to be (3.3 ± 0.4) × 10{sup 2 }cm{sup −1} in PVP and (3.7 ± 0.8) × 10{sup 2 }cm{sup −1} in PEG based on Marcus theory of electron transfer and Tang-Marcus model of blinking with statistical distribution.

Carrier mobility in double-helix DNA and RNA: A quantum chemistry study with Marcus-Hush theory.

PubMed

Wu, Tao; Sun, Lei; Shi, Qi; Deng, Kaiming; Deng, Weiqiao; Lu, Ruifeng

2016-12-21

Charge mobilities of six DNAs and RNAs have been computed using quantum chemistry calculation combined with the Marcus-Hush theory. Based on this simulation model, we obtained quite reasonable results when compared with the experiment, and the obtained charge mobility strongly depends on the molecular reorganization and electronic coupling. Besides, we find that hole mobilities are larger than electron mobilities no matter in DNAs or in RNAs, and the hole mobility of 2L8I can reach 1.09 × 10 -1 cm 2 V -1 s -1 which can be applied in the molecular wire. The findings also show that our theoretical model can be regarded as a promising candidate for screening DNA- and RNA-based molecular electronic devices.

Carrier mobility in double-helix DNA and RNA: A quantum chemistry study with Marcus-Hush theory

NASA Astrophysics Data System (ADS)

Wu, Tao; Sun, Lei; Shi, Qi; Deng, Kaiming; Deng, Weiqiao; Lu, Ruifeng

2016-12-01

Charge mobilities of six DNAs and RNAs have been computed using quantum chemistry calculation combined with the Marcus-Hush theory. Based on this simulation model, we obtained quite reasonable results when compared with the experiment, and the obtained charge mobility strongly depends on the molecular reorganization and electronic coupling. Besides, we find that hole mobilities are larger than electron mobilities no matter in DNAs or in RNAs, and the hole mobility of 2L8I can reach 1.09 × 10-1 cm2 V-1 s-1 which can be applied in the molecular wire. The findings also show that our theoretical model can be regarded as a promising candidate for screening DNA- and RNA-based molecular electronic devices.

Utopia and Education in Critical Theory

ERIC Educational Resources Information Center

Lewis, Tyson

2006-01-01

In this article the author examines the intimate connections between utopia and education in Frankfurt School critical theory. Although substantial links have been made in the critical pedagogy tradition between education, critique, and utopian dreaming, an in-depth analysis of the utopia-education matrix in the works of Herbert Marcuse, Theodor…

Unimolecular decomposition reactions at low-pressure: A comparison of competitive methods

NASA Technical Reports Server (NTRS)

Adams, G. F.

1980-01-01

The lack of a simple rate coefficient expression to describe the pressure and temperature dependence hampers chemical modeling of flame systems. Recently developed simplified models to describe unimolecular processes include the calculation of rate constants for thermal unimolecular reactions and recombinations at the low pressure limit, at the high pressure limit and in the intermediate fall-off region. Comparison between two different applications of Troe's simplified model and a comparison between the simplified model and the classic RRKM theory are described.

Electrochemical reduction of carbon fluorine bond in 4-fluorobenzonitrile Mechanistic analysis employing Marcus Hush quadratic activation-driving force relation

NASA Astrophysics Data System (ADS)

Muthukrishnan, A.; Sangaranarayanan, M. V.

2007-10-01

The reduction of carbon-fluorine bond in 4-fluorobenzonitrile in acetonitrile as the solvent, is analyzed using convolution potential sweep voltammetry and the dependence of the transfer coefficient on potential is investigated within the framework of Marcus-Hush quadratic activation-driving force theory. The validity of stepwise mechanism is inferred from solvent reorganization energy estimates as well as bond length calculations using B3LYP/6-31g(d) method. A novel method of estimating the standard reduction potential of the 4-fluorobenzonitrile in acetonitrile is proposed.

A Critical Theory Perspective on Accelerated Learning.

ERIC Educational Resources Information Center

Brookfield, Stephen D.

2003-01-01

Critically analyzes accelerated learning using concepts from Herbert Marcuse (rebellious subjectivity) and Erich Fromm (automaton conformity). Concludes that, by providing distance and separation, accelerated learning has more potential to stimulate critical autonomous thought. (SK)

Reactive trajectories of the Ru2+/3+ self-exchange reaction and the connection to Marcus' theory.

PubMed

Tiwari, Ambuj; Ensing, Bernd

2016-12-22

Outer sphere electron transfer between two ions in aqueous solution is a rare event on the time scale of first principles molecular dynamics simulations. We have used transition path sampling to generate an ensemble of reactive trajectories of the self-exchange reaction between a pair of Ru 2+ and Ru 3+ ions in water. To distinguish between the reactant and product states, we use as an order parameter the position of the maximally localised Wannier center associated with the transferring electron. This allows us to align the trajectories with respect to the moment of barrier crossing and compute statistical averages over the path ensemble. We compare our order parameter with two typical reaction coordinates used in applications of Marcus theory of electron transfer: the vertical gap energy and the solvent electrostatic potential at the ions.

Perfect in Every Sense. Scientific Iconography on an Equation Clock by Jost Bürgi and the Self-Understanding of the Astronomers at the Kassel Court in the Late 1580s.

PubMed

Gaulke, Karsten

2015-01-01

At the center of this article is an iconographic analysis of the eight silver reliefs on the sides of a table clock made in 1591 by Jost Burgi, the court clockmaker of Landgrave Wilhelm iv of Hessen-Kassel. The reliefs present an astronomical ancestral picture gallery, running from the Patriarchs of the Old Testament to Copernicus. The author argues that the "storyboard" for this sequence of images must have been conceived down to its smallest details by the Kassel court astronomer Christoph Rothmann; indeed, many of the scenes shown, along with many particular details depicted within them, are literally described in Rothmann's never-published manuscript Observationes stellarum fixarum of 1589. The final section of the essay compares these reliefs to the images created for Tycho Brahe at his Uraniborg and Stjerneborg observatories. The author concludes that the sequence of the reliefs in Kassel, culminating in the representation of Copernicus and his world view, is a reflection of the acrimonious debate extending over many years between the heliocentrist Rothmann and the geo-heliocentrist Brahe regarding the veracity of the heliocentric world view.

A Simple Geometric Model for the Marcus Theory of Proton Transfer

ERIC Educational Resources Information Center

McLennan, Duncan J.

1976-01-01

Uses the intersecting parabola model to derive an equation that relates the observed free energy of activation for a slow proton transfer to the overall thermodynamic free energy change in the reaction. (MLH)

Charge transfer kinetics at the solid-solid interface in porous electrodes

NASA Astrophysics Data System (ADS)

Bai, Peng; Bazant, Martin Z.

2014-04-01

Interfacial charge transfer is widely assumed to obey the Butler-Volmer kinetics. For certain liquid-solid interfaces, the Marcus-Hush-Chidsey theory is more accurate and predictive, but it has not been applied to porous electrodes. Here we report a simple method to extract the charge transfer rates in carbon-coated LiFePO4 porous electrodes from chronoamperometry experiments, obtaining curved Tafel plots that contradict the Butler-Volmer equation but fit the Marcus-Hush-Chidsey prediction over a range of temperatures. The fitted reorganization energy matches the Born solvation energy for electron transfer from carbon to the iron redox site. The kinetics are thus limited by electron transfer at the solid-solid (carbon-LixFePO4) interface rather than by ion transfer at the liquid-solid interface, as previously assumed. The proposed experimental method generalizes Chidsey’s method for phase-transforming particles and porous electrodes, and the results show the need to incorporate Marcus kinetics in modelling batteries and other electrochemical systems.

Access to enhanced differences in Marcus-Hush and Butler-Volmer electron transfer theories by systematic analysis of higher order AC harmonics.

PubMed

Stevenson, Gareth P; Baker, Ruth E; Kennedy, Gareth F; Bond, Alan M; Gavaghan, David J; Gillow, Kathryn

2013-02-14

The potential-dependences of the rate constants associated with heterogeneous electron transfer predicted by the empirically based Butler-Volmer and fundamentally based Marcus-Hush formalisms are well documented for dc cyclic voltammetry. However, differences are often subtle, so, presumably on the basis of simplicity, the Butler-Volmer method is generally employed in theoretical-experimental comparisons. In this study, the ability of Large Amplitude Fourier Transform AC Cyclic Voltammetry to distinguish the difference in behaviour predicted by the two formalisms has been investigated. The focus of this investigation is on the difference in the profiles of the first to sixth harmonics, which are readily accessible when a large amplitude of the applied ac potential is employed. In particular, it is demonstrated that systematic analysis of the higher order harmonic responses in suitable kinetic regimes provides predicted deviations of Marcus-Hush from Butler-Volmer behaviour to be established from a single experiment under conditions where the background charging current is minimal.

On the non-Arrhenius temperature dependence of the interwell electron tunneling rate in quasi two dimensional organic quantum wells

NASA Astrophysics Data System (ADS)

Jeong, I. S.; Scott, K.; Donovan, K. J.; Wilson, E. G.

2000-11-01

The tunneling rate of photocreated charge carriers between layers in Langmuir-Blodgett multilayer structures is measured indirectly using the novel technique of bimolecular recombination quenching. The tunneling rate is measured as a function of the applied electrostatic potential difference between the layers as the temperature is varied between 300 and 4 K. This dependence is examined in light of the Marcus theory of charge transfer where the electrostatic potential replaces the chemical potential as the driving potential. The expectations of the Marcus theory are not met and the rate is effectively temperature independent, contrary to expectation. Other mechanisms are explored that may explain the lack of temperature dependence including the role of high frequency vibrations and the role of the zero point energy of those vibrations. The temperature dependence of the exciton dissociation probability is also examined.

Direct measurements of rate coefficients for thermal decomposition of CF3I using shock—tube ARAS technique

NASA Astrophysics Data System (ADS)

Bystrov, N. S.; Emelianov, A. V.; Eremin, A. V.; Yatsenko, P. I.

2018-05-01

The kinetics of the dissociation of CF3I behind shock waves was experimentally investigated. The reaction CF3I  +  Ar  →  CF3  +  I  +  Ar was studied at temperatures between 900 and 1250 K and pressures of 2–3 bar. For this purpose, the time profiles of the concentration of atomic iodine were measured using a highly sensitive atomic resonance absorption spectroscopy method at a wavelength of 183.04 nm. From these data, the experimental value of the dissociation rate constant of CF3I was obtained: . We found that the investigated range of pressures and temperatures for the CF3I dissociation lies in the pressure transition region. Based on the Rice-Ramsperger–Kassel–Marcus theory, the threshold high and low-pressure rate constants ( and k 0) and falloff curves are calculated for the temperatures of 950–1200 K. As a result of this calculation, the threshold rate constants could be evaluated in the forms: and , and the center broadening factor, which takes into account the contribution of strong and weak collisions in the transition region, is .

Electrode redox reactions with polarizable molecules.

PubMed

Matyushov, Dmitry V

2018-04-21

A theory of redox reactions involving electron transfer between a metal electrode and a polarizable molecule in solution is formulated. Both the existence of molecular polarizability and its ability to change due to electron transfer distinguish this problem from classical theories of interfacial electrochemistry. When the polarizability is different between the oxidized and reduced states, the statistics of thermal fluctuations driving the reactant over the activation barrier becomes non-Gaussian. The problem of electron transfer is formulated as crossing of two non-parabolic free energy surfaces. An analytical solution for these free energy surfaces is provided and the activation barrier of electrode electron transfer is given in terms of two reorganization energies corresponding to the oxidized and reduced states of the molecule in solution. The new non-Gaussian theory is, therefore, based on two theory parameters in contrast to one-parameter Marcus formulation for electrode reactions. The theory, which is consistent with the Nernst equation, predicts asymmetry between the cathodic and anodic branches of the electrode current. They show different slopes at small electrode overpotentials and become curved at larger overpotentials. However, the curvature of the Tafel plot is reduced compared to the Marcus-Hush model and approaches the empirical Butler-Volmer form with different transfer coefficients for the anodic and cathodic currents.

Electrode redox reactions with polarizable molecules

NASA Astrophysics Data System (ADS)

Matyushov, Dmitry V.

2018-04-01

A theory of redox reactions involving electron transfer between a metal electrode and a polarizable molecule in solution is formulated. Both the existence of molecular polarizability and its ability to change due to electron transfer distinguish this problem from classical theories of interfacial electrochemistry. When the polarizability is different between the oxidized and reduced states, the statistics of thermal fluctuations driving the reactant over the activation barrier becomes non-Gaussian. The problem of electron transfer is formulated as crossing of two non-parabolic free energy surfaces. An analytical solution for these free energy surfaces is provided and the activation barrier of electrode electron transfer is given in terms of two reorganization energies corresponding to the oxidized and reduced states of the molecule in solution. The new non-Gaussian theory is, therefore, based on two theory parameters in contrast to one-parameter Marcus formulation for electrode reactions. The theory, which is consistent with the Nernst equation, predicts asymmetry between the cathodic and anodic branches of the electrode current. They show different slopes at small electrode overpotentials and become curved at larger overpotentials. However, the curvature of the Tafel plot is reduced compared to the Marcus-Hush model and approaches the empirical Butler-Volmer form with different transfer coefficients for the anodic and cathodic currents.

Eros and Thanatos: A Nondualistic Interpretation: The Dynamic of Drives in Personal and Civilizational Development From Freud to Marcuse.

PubMed

Kli, Maria

2018-02-01

The Freudian theory of drives gave prominence to the idea that there is an inherent principle of entropy, a tendency for dissolution of life, referred to as the Death drive, or Thanatos. Freud recognized a counterbalancing tendency for sustaining life, known as the Life drive, or Eros. The psychoanalytical expounding of the struggle of Eros and Thanatos in the context of the civilizational process sparked the philosophical critique of civilization. Although Freud tended to consider repression an indispensable dimension of this process, the author proposes in this paper that Herbert Marcuse's political critique took Freud's metapsychology further philosophically, suggesting a nondualistic interpretation of Freud's position.

Oxidation of dimethyl-ether and ethylene in the atmosphere and combustion environment and thermodynamic studies on hydrofluorocarbons usingab initio calculation methods

NASA Astrophysics Data System (ADS)

Yamada, Takahiro

1999-08-01

Reaction pathways and kinetics are analyzed on CH3OC.H2 unimolecular decay and on the complete CH3OC.H2 + O2 reaction system using thermodynamic properties DHdegf 298,Sdeg 298, and Cp(T) 300 <= T/K <= 1500) derived by two ab initio calculation methods, CBS-q and G2. These are used to determine thermodynamic properties of reactants, intermediate radicals and transition state (TS) compounds. Quantum Rice-Ramsperger-Kassel (QRRK) analysis is used to calculate energy dependent rate constants, k(E), and master equation is used to account for collisional stabilization. Comparison of calculated fall-off with experiment indicates that the CBS-q and G2 calculated Ea,rxn for the rate controlling transition state (β-scission reaction to CH 2O + C.H2OOH) needs to be lowered by factor of 3.3 kcal/mol and 4.0 kcal/mol respectively in order to match the data of Sehested et al. Experimental results on dimethyl-ether pyrolysis and oxidation reaction systems are compared with a detailed reaction mechanism model. The computer code CHEMKIN II is used for numerical integration. Overall agreement of the model data with experimental data is very good. Reaction pathways are analyzed and kinetics are determined on formation and reactions of the adduct resulting from OH addition to ethylene using the above ab initio methods. Hydrogen atom tunneling is included by use of Eckart formalism. Rate constants are compared with experimentally determined product branching ratios (C.H2CH 2OH stabilization: CH2O + CH3: CH3CHO + H). ab initio calculations are performed to estimate thermodynamic properties of nine fluorinated ethane compounds (fluoroethane to hexafluoroethane), eight fluoropropane (1-fluoropropane, 1,1- and 1,2- difluoropropane, 1,1,1- and 1,1,2-trifluoropropane, 1,1,1,2- and 1,1,2,2-tetrafluoropropane and 1,1,1,2,2- pentafluoropropane), and 2-fluoro,2-methylpropane. Standard entropies and heat capacities are calculated using the rigid-rotor-harmonic-oscillator approximation with direct integration over energy levels of the intramolecular rotation potential energy curve. Enthalpies of formation are estimated using G2MP2 total energies and isodesmic reactions. Thermodynamic properties for fluorinated carbon groups C/C/F/H2, C/C/F2/H, C/C/F3, C/C2/F/H, C/C2/F2 and C/C3/F for fluorinated alkane compounds, CD/F/H and CD/F2 for fluorinated alkene compounds and CT/F for fluorinated alkyne compounds are estimated. Fluorine-fluorine interaction terms F/F, 2F/F, 3F/F, 2F/2F, 3F/2F and 3F/3F for alkane compounds, F//F, 2F//F and 2F/2F for alkene compounds, and F///F for alkyne compound are also estimated.

76 FR 11961 - Safety Zone, Dredging Operations; Delaware River, Marcus Hook, PA

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-04

...-AA00 Safety Zone, Dredging Operations; Delaware River, Marcus Hook, PA AGENCY: Coast Guard, DHS. ACTION... Delaware River while the Dredge Pullen conducts dredging operations at the Sunoco Marcus Hook docks in the vicinity of the Marcus Hook Range near Marcus Hook, PA. This action is necessary to maintain the 42 ft...

Education as Simulation Game: A Critical Hermeneutic.

ERIC Educational Resources Information Center

Palermo, James

1979-01-01

This paper examines a specific educational game called "Popcorn Factory." First, it gives a detailed description of the game, then shifts the description into a critical hermeneutical framework, analyzing the deep structures at work in the "Popcorn Factory" according to the theories of Freud and Marcuse. (Author/SJL)

Critical Thinking as Cultural-Historical Practice.

ERIC Educational Resources Information Center

Panofsky, Carolyn P.

1999-01-01

Explores critical thinking as it has been constructed in schooling and in dominant traditions of psychological theory, presenting a dialectical view of critical thinking suggested in the social and philosophical writings of critical theorists (e.g., Theodor Adorno and Herbert Marcuse) and supported by the sociohistorical or cultural-historical…

Gas-phase binding energies for non-covalent Aβ-40 peptide/small molecule complexes from CID mass spectrometry and RRKM theory.

PubMed

Mayer, Paul M; Martineau, Eric

2011-03-21

The gas-phase binding of small molecules to the Amyloid β-40 peptide generated by electrospray ionization has been explored with collision-induced dissociation mass spectrometry and kinetic rate theory. This study discusses a simple procedure used to theoretically model the experimental breakdown diagrams for the Aβ-40 peptide complexed with a series of aminosulfonate small molecules, namely homotaurine, 3-cyclohexylamino-2-hydroxy-1-propanesulfonic acid (CAPSO), 3-(1,3,4,9-tetrahydro-2H-β-carbolin-2-yl)propane-1-sulfonic acid, 3-(1,3,4,9-tetrahydro-2H-β-carbolin-2-yl)butane-1-sulfonic acid, and 3-(cyclohexylamino)propane-1-sulfonic acid. An alternative procedure employing an extrapolation procedure for k(E) is also discussed.

Transition state theory thermal rate constants and RRKM-based branching ratios for the N((2)D) + CH(4) reaction based on multi-state and multi-reference ab initio calculations of interest for the Titan's chemistry.

PubMed

Ouk, Chanda-Malis; Zvereva-Loëte, Natalia; Scribano, Yohann; Bussery-Honvault, Béatrice

2012-10-30

Multireference single and double configuration interaction (MRCI) calculations including Davidson (+Q) or Pople (+P) corrections have been conducted in this work for the reactants, products, and extrema of the doublet ground state potential energy surface involved in the N((2)D) + CH(4) reaction. Such highly correlated ab initio calculations are then compared with previous PMP4, CCSD(T), W1, and DFT/B3LYP studies. Large relative differences are observed in particular for the transition state in the entrance channel resolving the disagreement between previous ab initio calculations. We confirm the existence of a small but positive potential barrier (3.86 ± 0.84 kJ mol(-1) (MR-AQCC) and 3.89 kJ mol(-1) (MRCI+P)) in the entrance channel of the title reaction. The correlation is seen to change significantly the energetic position of the two minima and five saddle points of this system together with the dissociation channels but not their relative order. The influence of the electronic correlation into the energetic of the system is clearly demonstrated by the thermal rate constant evaluation and it temperature dependance by means of the transition state theory. Indeed, only MRCI values are able to reproduce the experimental rate constant of the title reaction and its behavior with temperature. Similarly, product branching ratios, evaluated by means of unimolecular RRKM theory, confirm the NH production of Umemoto et al., whereas previous works based on less accurate ab initio calculations failed. We confirm the previous findings that the N((2)D) + CH(4) reaction proceeds via an insertion-dissociation mechanism and that the dominant product channels are CH(2)NH + H and CH(3) + NH. Copyright © 2012 Wiley Periodicals, Inc.

Stability Analysis of Finite Difference Approximations to Hyperbolic Systems, and Problems in Applied and Computational Matrix Theory

DTIC Science & Technology

1988-07-08

Marcus and C. Baczynski), Computer Science Press, Rockville, Maryland, 1986. 3. An Introduction to Pascal and Precalculus , Computer Science Press...Science Press, Rockville, Maryland, 1986. 35. An Introduction to Pascal and Precalculus , Computer Science Press, Rockville, Maryland, 1986. 36

Praxis Exiled: Herbert Marcuse and the One Dimensional University

ERIC Educational Resources Information Center

Cunningham, Joseph

2013-01-01

Leading Frankfurt School theorist, Herbert Marcuse, possessed an intricate relationship with higher education. As a professor, Marcuse participated in the 1960s student movements, believing that college students had potential as revolutionary subjects. Additionally, Marcuse advocated for a college education empowered by a form of praxis that…

Implications of Marcus-Hush theory for steady-state heterogeneous electron transfer at an inlaid disk electrode.

PubMed

Feldberg, Stephen W

2010-06-15

For an outer-sphere heterogeneous electron transfer, Ox + e = Red, between an electrode and a redox couple, the Butler-Volmer formalism predicts that the operative heterogeneous rate constant, k(red) (cm s(-1)) for reduction (or k(ox) for oxidation) increases without limit as an exponential function of -alpha (E - E(0)) for reduction (or (1 - alpha)(E - E(0)) for oxidation), where E is the applied electrode potential, alpha (~1/2) is the transfer coefficient and E(0) is the formal potential. The Marcus-Hush formalism, as exposited by Chidsey (Chidsey, C. E. D. Science 1991, 215, 919), predicts that the value of k(red) or k(ox) limits at sufficiently large values of -(E - E(0)) or (E - E(0)). The steady-state currents at an inlaid disk electrode obtained for a redox species in solution were computed using both formalisms with the Oldham-Zoski approximation (Oldham, K. B.; Zoski, C. G. J. Electroanal. Chem. 1988, 256, 11). Significant differences are noted for the two formalisms. When k(0)r(0)/D is sufficiently small (k(0) is the standard rate constant, r(0) is the radius of the disk electrode, and D is the diffusion coefficient of the redox species), the Marcus-Hush formalism effects a limiting current that can be significantly smaller than the mass transport limited current. This is easily explained in terms of the limiting values of k(red) and k(ox) predicted by the Marcus-Hush formalism. The experimental conditions that must be met to effect significant differences in behavior are discussed; experimental conditions that effect virtually identical behavior are also discussed. As a caveat for experimentalists, applications of the Butler-Volmer formalism to systems that are more properly described using the Marcus-Hush formalism are shown to yield incorrect values of k(0) and meaningless values of alpha, which serves only as a fitting parameter.

A nonmonotonic dependence of standard rate constant on reorganization energy for heterogeneous electron transfer processes on electrode surface

NASA Astrophysics Data System (ADS)

Xu, Weilin; Li, Songtao; Zhou, Xiaochun; Xing, Wei; Huang, Mingyou; Lu, Tianhong; Liu, Changpeng

2006-05-01

In the present work a nonmonotonic dependence of standard rate constant (k0) on reorganization energy (λ) was discovered qualitatively from electron transfer (Marcus-Hush-Levich) theory for heterogeneous electron transfer processes on electrode surface. It was found that the nonmonotonic dependence of k0 on λ is another result, besides the disappearance of the famous Marcus inverted region, coming from the continuum of electronic states in electrode: with the increase of λ, the states for both Process I and Process II ET processes all vary from nonadiabatic to adiabatic state continuously, and the λ dependence of k0 for Process I is monotonic thoroughly, while for Process II on electrode surface the λ dependence of k0 could show a nonmonotonicity.

Asymmetric Marcus-Hush theory for voltammetry.

PubMed

Laborda, Eduardo; Henstridge, Martin C; Batchelor-McAuley, Christopher; Compton, Richard G

2013-06-21

The current state-of-the-art in modeling the rate of electron transfer between an electroactive species and an electrode is reviewed. Experimental studies show that neither the ubiquitous Butler-Volmer model nor the more modern symmetric Marcus-Hush model are able to satisfactorily reproduce the experimental voltammetry for both solution-phase and surface-bound redox couples. These experimental deviations indicate the need for revision of the simplifying approximations used in the above models. Within this context, models encompassing asymmetry are considered which include different vibrational and solvation force constants for the electroactive species. The assumption of non-adiabatic electron transfer is also examined. These refinements have provided more satisfactory models of the electron transfer process and they enable us to gain more information about the microscopic characteristics of the system by means of simple electrochemical measurements.

Neoteny, Dialogic Education and an Emergent Psychoculture: Notes on Theory and Practice

ERIC Educational Resources Information Center

Kennedy, David

2014-01-01

This article argues that children represent one vanguard of an emergent shift in Western subjectivity, and that adult-child dialogue, especially in the context of schooling, is a key locus for the epistemological change that implies. Following Herbert Marcuse's invocation of a "new sensibility", the author argues that the…

Relative importance of driving force and electrostatic interactions in the reduction of multihaem cytochromes by small molecules.

PubMed

Quintas, Pedro O; Cepeda, Andreia P; Borges, Nuno; Catarino, Teresa; Turner, David L

2013-06-01

Multihaem cytochromes are essential to the energetics of organisms capable of bioremediation and energy production. The haems in several of these cytochromes have been discriminated thermodynamically and their individual rates of reduction by small electron donors were characterized. The kinetic characterization of individual haems used the Marcus theory of electron transfer and assumed that the rates of reduction of each haem by sodium dithionite depend only on the driving force, while electrostatic interactions were neglected. To determine the relative importance of these factors in controlling the rates, we studied the effect of ionic strength on the redox potential and the rate of reduction by dithionite of native Methylophilus methylotrophus cytochrome c″ and three mutants at different pH values. We found that the main factor determining the rate is the driving force and that Marcus theory describes this satisfactorily. This validates the method of the simultaneous fitting of kinetic and thermodynamic data in multihaem cytochromes and opens the way for further investigation into the mechanisms of these proteins. Copyright © 2013 Elsevier B.V. All rights reserved.

Computed rate coefficients and product yields for c-C5H5 + CH3 --> products.

PubMed

Sharma, Sandeep; Green, William H

2009-08-06

Using quantum chemical methods, we have explored the region of the C6H8 potential energy surface that is relevant in predicting the rate coefficients of various wells and major product channels following the reaction between cyclopentadienyl radical and methyl radical, c-C5H5 + CH3. Variational transition state theory is used to calculate the high-pressure-limit rate coefficient for all of the barrierless reactions. RRKM theory and the master equation are used to calculate the pressure dependent rate coefficients for 12 reactions. The calculated results are compared with the limited experimental data available in the literature and the agreement between the two is quite good. All of the rate coefficients calculated in this work are tabulated and can be used in building detailed chemical kinetic models.

A hybrid approach to simulation of electron transfer in complex molecular systems

PubMed Central

Kubař, Tomáš; Elstner, Marcus

2013-01-01

Electron transfer (ET) reactions in biomolecular systems represent an important class of processes at the interface of physics, chemistry and biology. The theoretical description of these reactions constitutes a huge challenge because extensive systems require a quantum-mechanical treatment and a broad range of time scales are involved. Thus, only small model systems may be investigated with the modern density functional theory techniques combined with non-adiabatic dynamics algorithms. On the other hand, model calculations based on Marcus's seminal theory describe the ET involving several assumptions that may not always be met. We review a multi-scale method that combines a non-adiabatic propagation scheme and a linear scaling quantum-chemical method with a molecular mechanics force field in such a way that an unbiased description of the dynamics of excess electron is achieved and the number of degrees of freedom is reduced effectively at the same time. ET reactions taking nanoseconds in systems with hundreds of quantum atoms can be simulated, bridging the gap between non-adiabatic ab initio simulations and model approaches such as the Marcus theory. A major recent application is hole transfer in DNA, which represents an archetypal ET reaction in a polarizable medium. Ongoing work focuses on hole transfer in proteins, peptides and organic semi-conductors. PMID:23883952

A nonmonotonic dependence of standard rate constant on reorganization energy for heterogeneous electron transfer processes on electrode surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu Weilin; Li Songtao; Zhou Xiaochun

2006-05-07

In the present work a nonmonotonic dependence of standard rate constant (k{sup 0}) on reorganization energy ({lambda}) was discovered qualitatively from electron transfer (Marcus-Hush-Levich) theory for heterogeneous electron transfer processes on electrode surface. It was found that the nonmonotonic dependence of k{sup 0} on {lambda} is another result, besides the disappearance of the famous Marcus inverted region, coming from the continuum of electronic states in electrode: with the increase of {lambda}, the states for both Process I and Process II ET processes all vary from nonadiabatic to adiabatic state continuously, and the {lambda} dependence of k{sup 0} for Process Imore » is monotonic thoroughly, while for Process II on electrode surface the {lambda} dependence of k{sup 0} could show a nonmonotonicity.« less

Taxonomic review of the family Discodorididae (Mollusca: Gastropoda: Nudibranchia) from Brazil, with descriptions of two new species.

PubMed

Alvim, Juliana; Pimenta, Alexandre Dias

2013-12-04

The family Discodorididae was previously represented by 11 species in Brazil; however, recently collected specimens from several localities in Rio de Janeiro, in addition to the study of material previously deposited in scientific collections, revealed the existence of 13 taxa: Diaulula greeleyi (MacFarland, 1909), Discodoris hummelincki (Ev. Marcus & Er. Marcus, 1963) comb. nov., Discodoris branneri MacFarland, 1909, Geitodoris pusae (Er. Marcus, 1955), Hoplodoris hansrosaorum Domínguez, García & Troncoso, 2006, Jorunna spazzola Er. Marcus, 1955, Jorunna spongiosa sp. nov., Paradoris mulciber (Ev. Marcus, 1971), Platydoris angustipes (Mörch, 1863), Rostanga byga Er. Marcus, 1958a, Taringa telopia Er. Marcus, 1955, Taringa iemanja sp. nov., and Thordisa diuda Er. Marcus, 1955. Discodoris voniheringi MacFarland, 1909 was previously regarded as nomen dubium, and this view is maintained in the present study. Three new records for the Brazilian coast are recognized among these 13 taxa; the previous record of Diaulula phoca (Ev. Marcus & Er. Marcus, 1967a) is rectified as Discodoris hummelincki comb. nov., constituting the first record of this species from Brazil; two new species, Taringa iemanja sp. nov. and Jorunna spongiosa sp. nov., are described in anatomical detail. The following taxa, which were formerly considered junior synonyms of species studied in this work, have been revalidated: Diaulula nayarita (Ortea & Llera, 1981), from the Pacific coast of Costa Rica, which differs from Diaulula greeleyi in the length and width of caryophyllidia; Discodoris mortenseni Ev. Marcus & Er. Marcus, 1963, from the Caribbean, which is likely to belong to Jorunna, yet differs from Jorunna spazzola in body size and coloration, radula appearance, and number of lamellae in the rhinophores; Jorunna luisae Ev. Marcus, 1976, which differs from Jorunna spazzola in the reproductive system, mainly in the size and shape of the accessory gland; and Thordisa azmani Cervera & García-Gómez, 1989, which differs from Thordisa diuda in the presence of two accessory glands in the genital atrium and the absence of one denticle in the external surface of the inner lateral teeth. Finally, the specimens of Geitodoris pusae reported from the European coast and Mediterranean Sea show differences in general coloration and in the radula, gill, and reproductive system, thereby these specimens likely refer to different taxa.

Proceedings of the International Symposium on Methodologies for Intelligent Systems (Poster Session) (7th) held at Trondheim, Norway, on 15-18 June, 1993

DTIC Science & Technology

1993-06-18

David Hislop (US Army Research Office), Eero Hyvonen (VTT, Finland), Marek Karpinski (Bonn, Germany), Yves Kodratoff (Paris VI, France), Jan...21] M. P. Marcus, A theory of Syntactic Recognition for Natural Language, The MIT Press, Cambridge, Mass., 1980 [221 K.R. McKeown, The TEXT System...H. Simon, The Sciences of the Artificial, The MIT Press, Cambridge, MA, ( 1980 ). 3. M.D. Mesarovich, D. Macko, Y. Takahara Y., Theory of Hierarchical

Organic magnetoresistance based on hopping theory

NASA Astrophysics Data System (ADS)

Yang, Fu-Jiang; Xie, Shi-Jie

2014-09-01

For the organic magnetoresistance (OMAR) effect, we suggest a spin-related hopping of carriers (polarons) based on Marcus theory. The mobility of polarons is calculated with the master equation (ME) and then the magnetoresistance (MR) is obtained. The theoretical results are consistent with the experimental observation. Especially, the sign inversion of the MR under different driving bias voltages found in the experiment is predicted. Besides, the effects of molecule disorder, hyperfine interaction (HFI), polaron localization, and temperature on the MR are investigated.

Herbert Marcuse's Theory of Play--A Social Philosophical Perspective.

ERIC Educational Resources Information Center

Volkwien, Karin A. E.

Sport has been widely discussed, by conservatives who argue that sport operates within the realm of freedom, and so lies outside the deterministic nexus of capitalist economics and policies, and leftists who argue that sport reproduces the repressive features of capitalism and serves as an ideological tool of the latter. The purpose of this study…

Theoretical Aspects of Target Classification. Lecture Series of the Electromagnetic Wave Propagation Panel and the Consultant and Exchange Programme Held in Rome, Italy on 29-30 June 1987; Neuiberg, Germany on 2-3 July 1987 and Noresund, Norway on 6-7 July 1987.

DTIC Science & Technology

1987-06-01

F1116 81031 Oherpifaffenhofen Wilhelmnshohec Alice 73 Federal Republic of Gierman!, D-3500 Kassel Federal Republic of German %’ CONTENTS Page LIST OF...Report, University of Kassel, 1984 (in German ). 45. H. Shirai and L.B. Felsen, "Modified GTD for Generating Complex Resonances for Flat Strips and Disks...Thompr~son. litJ. t’himnti) Plenum Press. New York 1986. ACK14OWLEDGEMENTS This work has been financially sullpported hv the Stifting Volkswagen Werk

Electron transfer rate on mixed valence states of Class II/III transition for N, N'-diphenyl-1,4-phenylenediamine structures as a polyaniline unit

NASA Astrophysics Data System (ADS)

Nishiumi, Toyohiko; Nomura, Yasuhiro; Higuchi, Masayoshi; Yamamoto, Kimihisa

2003-08-01

The first example of the determination of the electron transfer rate ( λ, V, Δ G*, kth) for N, N'-diphenyl-1,4-phenylenediamine derivatives using the Marcus-Hush theory is described. These results were in good agreement with the ones obtained using variable-temperature IR spectra measurements.

Theory, Observation, and Validation: Commentary on Almond, Kim, Velasquez, & Shute

ERIC Educational Resources Information Center

Markus, Keith A.

2014-01-01

Keith Marcus congratulates Almond et al. on an interesting article bringing together two topics that are important to the field of testing. He states that some aspects of the exposition came across as not yet fully developed, as if the manuscript had been hurried to press. In this commentary, he attempts to expand aspects of the article, which he…

System-of-Systems Test Planning in a Complex Joint Environment

DTIC Science & Technology

2007-06-01

Marcus Aurelius Marcus Aurelius , Emperor of the Roman Empire from 161-180 A.D., was considered one of the great Stoic philosophers.30 The Stoic...number of experimental runs. 30 For more on Marcus Arelius and Stoic philosophy see http

A new feature in the internal heavy isotope distribution in ozone.

PubMed

Bhattacharya, S K; Savarino, Joel; Michalski, G; Liang, Mao-Chang

2014-10-07

Ozone produced by discharge or photolysis of oxygen has unusually heavy isotopic composition ((18)O/(16)O and (17)O/(16)O ratio) which does not follow normal mass fractionation rule: δ(17)O ∼ 0.52(*)δ(18)O, expressed as an anomaly Δ(17)O = δ(17)O - 0.52(*)δ(18)O. Ozone molecule being an open isosceles triangle can have the heavy isotope located either in its apex or symmetric (s) position or the base or asymmetric (as) position. Correspondingly, one can define positional isotopic enrichment, written as δ(18)O (s) or δ(18)O (as) (and similarly for δ(17)O) as well as position dependent isotope anomaly Δ(17)O (s) and Δ(17)O (as). Marcus and co-workers have proposed a semi-empirical model based in principle on the RRKM model of uni-molecular dissociation but with slight modification (departure from statistical randomness assumption for symmetrical molecules) which explains many features of ozone isotopic enrichment. This model predicts that the bulk isotope anomaly is contained wholly in the asymmetric position and the Δ(17)O (s) is zero. Consequently, Δ(17)O (as) = 1.5 (*) Δ(17)O (bulk) (named here simply as the "1.5 rule") which has been experimentally confirmed over a range of isotopic enrichment. We now show that a critical re-analysis of the earlier experimental data demonstrates a small but significant departure from this 1.5 rule at the highest and lowest levels of enrichments. This departure provides the first experimental proof that the dynamics of ozone formation differs from a statistical model constrained only by restriction of symmetry. We speculate over some possible causes for the departure.

A new feature in the internal heavy isotope distribution in ozone

NASA Astrophysics Data System (ADS)

Bhattacharya, S. K.; Savarino, Joel; Michalski, G.; Liang, Mao-Chang

2014-10-01

Ozone produced by discharge or photolysis of oxygen has unusually heavy isotopic composition (18O/16O and 17O/16O ratio) which does not follow normal mass fractionation rule: δ17O ˜ 0.52*δ18O, expressed as an anomaly Δ17O = δ17O - 0.52*δ18O. Ozone molecule being an open isosceles triangle can have the heavy isotope located either in its apex or symmetric (s) position or the base or asymmetric (as) position. Correspondingly, one can define positional isotopic enrichment, written as δ18O (s) or δ18O (as) (and similarly for δ17O) as well as position dependent isotope anomaly Δ17O (s) and Δ17O (as). Marcus and co-workers have proposed a semi-empirical model based in principle on the RRKM model of uni-molecular dissociation but with slight modification (departure from statistical randomness assumption for symmetrical molecules) which explains many features of ozone isotopic enrichment. This model predicts that the bulk isotope anomaly is contained wholly in the asymmetric position and the Δ17O (s) is zero. Consequently, Δ17O (as) = 1.5 * Δ17O (bulk) (named here simply as the "1.5 rule") which has been experimentally confirmed over a range of isotopic enrichment. We now show that a critical re-analysis of the earlier experimental data demonstrates a small but significant departure from this 1.5 rule at the highest and lowest levels of enrichments. This departure provides the first experimental proof that the dynamics of ozone formation differs from a statistical model constrained only by restriction of symmetry. We speculate over some possible causes for the departure.

Unified theory of the exciplex formation/dissipation.

PubMed

Khokhlova, Svetlana S; Burshtein, Anatoly I

2010-11-04

The natural extension and reformulation of the unified theory (UT) proposed here makes it integro-differential and capable of describing the distant quenching of excitation by electron transfer, accompanied with contact but reversible exciplex formation. The numerical solution of the new UT equations allows specifying the kinetics of the fluorescence quenching and exciplex association/dissociation as well as those reactions' quantum yields. It was demonstrated that the distant electron transfer in either the normal or inverted Marcus regions screens the contact reaction of exciplex formation, especially at slow diffusion.

The Operations Targeting and Effects Synchronization Process in Northern Iraq

DTIC Science & Technology

2010-06-01

deployment. _____________ IMAGE: Coin of Marcus Aurelius . The secret of all victory lies in the organization of the non-obvious. — Marcus Aurelius , 121-180...CE IN THE EARLY 4th century BCE, more than five centuries before the great philosopher-emperor Marcus Aurelius made the observation quoted above

Structure and Dynamics of Solvent Landscapes in Charge-Transfer Reactions

NASA Astrophysics Data System (ADS)

Leite, Vitor B. Pereira

The dynamics of solvent polarization plays a major role in the control of charge transfer reactions. The success of Marcus theory describing the solvent influence via a single collective quadratic polarization coordinate has been remarkable. Onuchic and Wolynes have recently proposed (J. Chem Phys 98 (3) 2218, 1993) a simple model demonstrating how a many-dimensional-complex model composed by several dipole moments (representing solvent molecules or polar groups in proteins) can be reduced under the appropriate limits into the Marcus Model. This work presents a dynamical study of the same model, which is characterized by two parameters, an average dipole-dipole interaction as a term associated with the potential energy landscape roughness. It is shown why the effective potential, obtained using a thermodynamic approach, is appropriate for the dynamics of the system. At high temperatures, the system exhibits effective diffusive one-dimensional dynamics, where the Born-Marcus limit is recovered. At low temperatures, a glassy phase appears with a slow non-self-averaging dynamics. At intermediate temperatures, the concept of equivalent diffusion paths and polarization dependence effects are discussed. This approach is extended to treat more realistic solvent models. Real solvents are discussed in terms of simple parameters described above, and an analysis of how different regimes affect the rate of charge transfer is presented. Finally, these ideas are correlated to analogous problems in other areas.

Evidence of the Ideology of Marcus Fabius Quintilianus in Three Periods of American Educational Thought: 1750-1980

ERIC Educational Resources Information Center

Kasper, Beverly B.

2004-01-01

Nearly two thousand years ago, Quintilian wrote a guide for the education of the ideal citizen which combined theory with educational practice. He believed in the importance of early education, the place of play and joy in learning, the necessity to base education on students' individual patterns of growth and learning, the magnitude of the…

Ab initio chemical kinetics for the HCCO + OH reaction

NASA Astrophysics Data System (ADS)

Mai, Tam V.-T.; Raghunath, P.; Le, Xuan T.; Huynh, Lam K.; Nam, Pham-Cam; Lin, M. C.

2014-01-01

The mechanism for the reaction of HCCO and OH has been investigated at different high-levels of theory. The reaction was found to occur on singlet and triplet potential energy surfaces with multiple accessible paths. Rate constants predicted by variational RRKM/ME calculations show that the reaction on both surfaces occurs primarily by barrierless OH attack at both C atoms producing excited intermediates which fragment to produce predominantly CO and 1,3HCOH with kS = 3.12 × 10-8T-0.59exp[-73.0/T] and kT = 6.29 × 10-11T0.13exp[108/T] cm3 molecule-1 s-1 at T = 300-2000 K, independent of pressure at P < 76 000 Torr.

Time-resolved gas-phase kinetic, quantum chemical, and RRKM studies of reactions of silylene with alcohols.

PubMed

Becerra, Rosa; Cannady, J Pat; Walsh, Robin

2011-05-05

Time-resolved kinetic studies of silylene, SiH(2), generated by laser flash photolysis of 1-silacyclopent-3-ene and phenylsilane, have been carried out to obtain rate constants for its bimolecular reactions with methanol, ethanol, 1-propanol, 1-butanol, and 2-methyl-1-butanol. The reactions were studied in the gas phase over the pressure range 1-100 Torr in SF(6) bath gas, at room temperature. In the study with methanol several buffer gases were used. All five reactions showed pressure dependences characteristic of third body assisted association reactions. The rate constant pressure dependences were modeled using RRKM theory, based on E(0) values of the association complexes obtained by ab initio calculation (G3 level). Transition state models were adjusted to fit experimental fall-off curves and extrapolated to obtain k(∞) values in the range (1.9-4.5) × 10(-10) cm(3) molecule(-1) s(-1). These numbers, corresponding to the true bimolecular rate constants, indicate efficiencies of between 16% and 67% of the collision rates for these reactions. In the reaction of SiH(2) + MeOH there is a small kinetic component to the rate which is second order in MeOH (at low total pressures). This suggests an additional catalyzed reaction pathway, which is supported by the ab initio calculations. These calculations have been used to define specific MeOH-for-H(2)O substitution effects on this catalytic pathway. Where possible our experimental and theoretical results are compared with those of previous studies.

New theory for Mode I crack-tip dislocation emission

NASA Astrophysics Data System (ADS)

Andric, Predrag; Curtin, W. A.

2017-09-01

A material is intrinsically ductile under Mode I loading when the critical stress intensity KIe for dislocation emission is lower than the critical stress intensity KIc for cleavage. KIe is usually evaluated using the approximate Rice theory, which predicts a dependence on the elastic constants and the unstable stacking fault energy γusf for slip along the plane of dislocation emission. Here, atomistic simulations across a wide range of fcc metals show that KIe is systematically larger (10-30%) than predicted. However, the critical (crack tip) shear displacement is up to 40% smaller than predicted. The discrepancy arises because Mode I emission is accompanied by the formation of a surface step that is not considered in the Rice theory. A new theory for Mode I emission is presented based on the ideas that (i) the stress resisting step formation at the crack tip creates "lattice trapping" against dislocation emission such that (ii) emission is due to a mechanical instability at the crack tip. The new theory is formulated using a Peierls-type model, naturally includes the energy to form the step, and reduces to the Rice theory (no trapping) when the step energy is small. The new theory predicts a higher KIe at a smaller critical shear displacement, rationalizing deviations of simulations from the Rice theory. Specific predictions of KIe for the simulated materials, usually requiring use of the measured critical crack tip shear displacement due to complex material non-linearity, show very good agreement with simulations. An analytic model involving only γusf, the surface energy γs, and anisotropic elastic constants is shown to be quite accurate, serves as a replacement for the analytical Rice theory, and is used to understand differences between Rice theory and simulation in recent literature. The new theory highlights the role of surface steps created by dislocation emission in Mode I, which has implications not only for intrinsic ductility but also for crack tip twinning and fracture due to chemical interactions at the crack tip.

Theoretical study on the charge transport in single crystals of TCNQ, F2-TCNQ and F4-TCNQ.

PubMed

Ji, Li-Fei; Fan, Jian-Xun; Zhang, Shou-Feng; Ren, Ai-Min

2018-01-31

2,5-Difluoro-7,7,8,8-tetracyanoquinodimethane (F 2 -TCNQ) was recently reported to display excellent electron transport properties in single crystal field-effect transistors (FETs). Its carrier mobility can reach 25 cm 2 V -1 s -1 in devices. However, its counterparts TCNQ and F 4 -TCNQ (tetrafluoro-7,7,8,8-tetracyanoquinodimethane) do not exhibit the same highly efficient behavior. To better understand this significant difference in charge carrier mobility, a multiscale approach combining semiclassical Marcus hopping theory, a quantum nuclear enabled hopping model and molecular dynamics simulations was performed to assess the electron mobilities of the F n -TCNQ (n = 0, 2, 4) systems in this work. The results indicated that the outstanding electron transport behavior of F 2 -TCNQ arises from its effective 3D charge carrier percolation network due to its special packing motif and the nuclear tunneling effect. Moreover, the poor transport properties of TCNQ and F 4 -TCNQ stem from their invalid packing and strong thermal disorder. It was found that Marcus theory underestimated the mobilities for all the systems, while the quantum model with the nuclear tunneling effect provided reasonable results compared to experiments. Moreover, the band-like transport behavior of F 2 -TCNQ was well described by the quantum nuclear enabled hopping model. In addition, quantum theory of atoms in molecules (QTAIM) analysis and symmetry-adapted perturbation theory (SAPT) were used to characterize the intermolecular interactions in TCNQ, F 2 -TCNQ and F 4 -TCNQ crystals. A primary understanding of various noncovalent interaction responses for crystal formation is crucial to understand the structure-property relationships in organic molecular materials.

Marcus canonical integral for non-Gaussian processes and its computation: pathwise simulation and tau-leaping algorithm.

PubMed

Li, Tiejun; Min, Bin; Wang, Zhiming

2013-03-14

The stochastic integral ensuring the Newton-Leibnitz chain rule is essential in stochastic energetics. Marcus canonical integral has this property and can be understood as the Wong-Zakai type smoothing limit when the driving process is non-Gaussian. However, this important concept seems not well-known for physicists. In this paper, we discuss Marcus integral for non-Gaussian processes and its computation in the context of stochastic energetics. We give a comprehensive introduction to Marcus integral and compare three equivalent definitions in the literature. We introduce the exact pathwise simulation algorithm and give the error analysis. We show how to compute the thermodynamic quantities based on the pathwise simulation algorithm. We highlight the information hidden in the Marcus mapping, which plays the key role in determining thermodynamic quantities. We further propose the tau-leaping algorithm, which advance the process with deterministic time steps when tau-leaping condition is satisfied. The numerical experiments and its efficiency analysis show that it is very promising.

Diffraction Pattern Analysis as an Optical Inspection Technique

DTIC Science & Technology

1991-08-01

BACKGROUND Diameters of fiber samples have commonly been measured manually with an optical microscope. Marcuse and Presby developed an automatic...by analyzing the back-scattered light when a beam of laser light impinged upon the fiber [2]. Presby and Marcuse extended this back-scattering tech...be im- proved further in order to become a feasible method for detecting a small number of blocked openings in CRT screens. 20 REFERENCES 1. Marcuse

Estimation of the outer-sphere contribution to the activation volume for electron exchange reactions using the mean spherical approximation

NASA Astrophysics Data System (ADS)

Takagi, Hideo D.; Swaddle, Thomas W.

1996-01-01

The outer-sphere contribution to the volume of activation of homogeneous electron exchange reactions is estimated for selected solvents on the basis of the mean spherical approximation (MSA), and the calculated values are compared with those estimated by the Strank-Hush-Marcus (SHM) theory and with activation volumes obtained experimentally for the electron exchange reaction between tris(hexafluoroacetylacetonato)ruthenium(III) and -(II) in acetone, acetonitrile, methanol and chloroform. The MSA treatment, which recognizes the molecular nature of the solvent, does not improve significantly upon the continuous-dielectric SHM theory, which represents the experimental data adequately for the more polar solvents.

The charger transfer electronic coupling in diabatic perspective: A multi-state density functional theory study

NASA Astrophysics Data System (ADS)

Guo, Xinwei; Qu, Zexing; Gao, Jiali

2018-01-01

The multi-state density functional theory (MSDFT) provides a convenient way to estimate electronic coupling of charge transfer processes based on a diabatic representation. Its performance has been benchmarked against the HAB11 database with a mean unsigned error (MUE) of 17 meV between MSDFT and ab initio methods. The small difference may be attributed to different representations, diabatic from MSDFT and adiabatic from ab initio calculations. In this discussion, we conclude that MSDFT provides a general and efficient way to estimate the electronic coupling for charge-transfer rate calculations based on the Marcus-Hush model.

Symmetrical windowing for quantum states in quasi-classical trajectory simulations: Application to electron transfer

NASA Astrophysics Data System (ADS)

Cotton, Stephen J.; Igumenshchev, Kirill; Miller, William H.

2014-08-01

It has recently been shown [S. J. Cotton and W. H. Miller, J. Chem. Phys. 139, 234112 (2013)] that a symmetrical windowing quasi-classical (SQC) approach [S. J. Cotton and W. H. Miller, J. Phys. Chem. A 117, 7190 (2013)] applied to the Meyer-Miller model [H.-D. Meyer and W. H. Miller, J. Chem. Phys. 70, 3214 (1979)] for the electronic degrees of freedom in electronically non-adiabatic dynamics is capable of quantitatively reproducing quantum mechanical results for a variety of test applications, including cases where "quantum" coherence effects are significant. Here we apply this same SQC methodology, within a flux-side correlation function framework, to calculate thermal rate constants corresponding to several proposed models of electron transfer processes [P. Huo, T. F. Miller III, and D. F. Coker, J. Chem. Phys. 139, 151103 (2013); A. R. Menzeleev, N. Ananth, and T. F. Miller III, J. Chem. Phys. 135, 074106 (2011)]. Good quantitative agreement with Marcus Theory is obtained over several orders of magnitude variation in non-adiabatic coupling. Moreover, the "inverted regime" in thermal rate constants (with increasing bias) known from Marcus Theory is also reproduced with good accuracy by this very simple classical approach. The SQC treatment is also applied to a recent model of photoinduced proton coupled electron transfer [C. Venkataraman, A. V. Soudackov, and S. Hammes-Schiffer, J. Chem. Phys. 131, 154502 (2009)] and population decay of the photoexcited donor state is found to be in reasonable agreement with results calculated via reduced density matrix theory.

Symmetrical windowing for quantum states in quasi-classical trajectory simulations: Application to electron transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cotton, Stephen J.; Igumenshchev, Kirill; Miller, William H., E-mail: millerwh@berkeley.edu

It has recently been shown [S. J. Cotton and W. H. Miller, J. Chem. Phys. 139, 234112 (2013)] that a symmetrical windowing quasi-classical (SQC) approach [S. J. Cotton and W. H. Miller, J. Phys. Chem. A 117, 7190 (2013)] applied to the Meyer-Miller model [H.-D. Meyer and W. H. Miller, J. Chem. Phys. 70, 3214 (1979)] for the electronic degrees of freedom in electronically non-adiabatic dynamics is capable of quantitatively reproducing quantum mechanical results for a variety of test applications, including cases where “quantum” coherence effects are significant. Here we apply this same SQC methodology, within a flux-side correlation functionmore » framework, to calculate thermal rate constants corresponding to several proposed models of electron transfer processes [P. Huo, T. F. Miller III, and D. F. Coker, J. Chem. Phys. 139, 151103 (2013); A. R. Menzeleev, N. Ananth, and T. F. Miller III, J. Chem. Phys. 135, 074106 (2011)]. Good quantitative agreement with Marcus Theory is obtained over several orders of magnitude variation in non-adiabatic coupling. Moreover, the “inverted regime” in thermal rate constants (with increasing bias) known from Marcus Theory is also reproduced with good accuracy by this very simple classical approach. The SQC treatment is also applied to a recent model of photoinduced proton coupled electron transfer [C. Venkataraman, A. V. Soudackov, and S. Hammes-Schiffer, J. Chem. Phys. 131, 154502 (2009)] and population decay of the photoexcited donor state is found to be in reasonable agreement with results calculated via reduced density matrix theory.« less

Teasing out specific language impairment from an autism spectrum disorder.

PubMed

Tierney, Cheryl D; Gupta, Vidya Bhushan; Angel, Alma Patricia Del; Augustyn, Marilyn

2012-04-01

Marcus is a handsome, sweet, 7½-year-old boy with a significant history of delayed development, specifically in speech and language skills, as well as difficulties with social interactions that have led other specialists to be concerned about a diagnosis of an autism spectrum disorder.He has been seen in our primary care practice since birth. He was born full-term after vaginal delivery weighing 6 pounds, 6 ounces. There were no pregnancy or delivery complications noted. Genetic testing revealed normal chromosomes, fragile X, and microarray testing. Marcus was a picky eater and good sleeper and had delays in toilet training.There is no family history of attention-deficit hyperactivity disorder (ADHD), autism, or substance abuse. Maternal grandmother and mother have a history of learning difficulties, and his father and a paternal uncle have a history of depression and anxiety. Marcus lives in a supportive environment with his mother, father, and sister.Marcus was noted to have significantly delayed language, stuttering, and immediate echolalia as a toddler. Gross and fine motor milestones were met on time, but he did not talk or follow directions until 4 to 5 years old. As a younger child, he would pretend to talk on the phone or mow the grass with a pretend lawn mower, but other household activities were not of interest to Marcus.Currently, he enjoys puzzles, reading, and board games. He likes to play with other children and can interact with familiar adults. Marcus is reported to initiate social interactions, although he has difficulty in understanding personal space. Imaginative play is preferred over other types. He seeks out adult attention and will bring objects over to an adult especially to share his perceived accomplishment. Marcus has difficulty in playing cooperatively with his sister.He is independent with activities of daily living. Marcus is noted to have auditory defensiveness including covering his ears to loud noises and becoming distressed. Parents feel he is immature and inattentive for his age. Marcus responds well when a routine is followed.Previous testing about 2 years ago revealed significant language deficits on the Clinical Evaluation of Language Functioning with average scores on the Woodcock Johnson Achievement Testing and Test of Nonverbal Intelligence Version 3. Marcus was not referred for early intervention and he did not attend preschool. In a regular education Kindergarten, he received speech and occupational therapy along with reading and math support.Comments from teachers or evaluator include the following: Marcus looked to his peers for clues about what he should be doing. Marcus has great difficulty in understanding requests but seems to be interested in pleasing his teacher and others. Marcus' language difficulty makes socialization with his peers problematic; however, he is interested in interacting with them and they seem to accept him willingly. Marcus has intent to communicate with others but relies on visual support to decipher social situations. Marcus has difficulty in attending to details and moves from activity to activity quickly. His short attention span is likely impacting not only learning but also his ability to socially interact with peers.On the day you see him for his 7-year-old checkup, he brought many toys over to show his father and interrupted your conversation to get your attention intermittently throughout the examination. He immediately pointed out a lit ceiling tile with Nemo illuminated to show his father. Marcus does not have any notable or significant repetitive motor mannerisms or stereotypies reported or observed. Marcus' gesture use was appropriate for age and included both symbolic (directing eye gaze and pointing) and concrete (hands up to be picked up and touching an item rather than pointing to it) gestures. Play observed today, although immature for age, was novel, imaginative, and functional. Answers to questions did not always match the question posed. He had a difficult time waiting for his turn before interrupting a conversation. Visual cues were helpful in understanding what was expected of him and what was going on socially.Marcus' speech is notable for persistent stuttering and difficulty in turn-taking in conversation. He gets frustrated easily and has a hard time being understood. He continues to confuse pronouns and makes some grammatical errors. He is able to follow simple directions but has a hard time following complex or multistep directions with accuracy. Nonverbal communication includes pointing to objects of interest in order to share the experience ("Look mom!"). He will point to identify an object and can follow a point across the room. He is able to use his eye contact to direct yours to moderate social interactions.Marcus has a special interest in Thomas the Tank Engine Train and Disney movies but is able to move away from those topics to engage in other play interests. Repetitive behaviors are not noted. Toe walking, hand flapping, or spinning, or unusual hand motions or observation of objects were not observed.Difficulties noted today include delays in his receptive and expressive language, poor intelligibility, dysfluency, and impaired motor planning. He recently underwent an audiogram which was normal. You decide to refer to a specialist for further evaluation.

Theoretical Studies of Low-Loss Optical Fibers.

DTIC Science & Technology

1980-09-15

on the fiber surface. Single-mode fiber operation is of interest in communications. Marcuse has shown that surface imperfections are a strong source...0.01 very small value of a : 8A at X = 1 vim Marcuse single mode 2.7 typical value of a = 1 jim, A : 10.6 vm, af = 37 Pim surface imperfections 55...Braunstein, "Scattering Losses in Single and Polycrystalline Materials for Infrared Fiber Applications," unpublished. 5. D. Marcuse , "Mode Conversion

Can we Predict Quantum Yields Using Excited State Density Functional Theory for New Families of Fluorescent Dyes?

NASA Astrophysics Data System (ADS)

Kohn, Alexander W.; Lin, Zhou; Shepherd, James J.; Van Voorhis, Troy

2016-06-01

For a fluorescent dye, the quantum yield characterizes the efficiency of energy transfer from the absorbed light to the emitted fluorescence. In the screening among potential families of dyes, those with higher quantum yields are expected to have more advantages. From the perspective of theoreticians, an efficient prediction of the quantum yield using a universal excited state electronic structure theory is in demand but still challenging. The most representative examples for such excited state theory include time-dependent density functional theory (TDDFT) and restricted open-shell Kohn-Sham (ROKS). In the present study, we explore the possibility of predicting the quantum yields for conventional and new families of organic dyes using a combination of TDDFT and ROKS. We focus on radiative (kr) and nonradiative (knr) rates for the decay of the first singlet excited state (S_1) into the ground state (S_0) in accordance with Kasha's rule. M. Kasha, Discuss. Faraday Soc., 9, 14 (1950). For each dye compound, kr is calculated with the S_1-S_0 energy gap and transition dipole moment obtained using ROKS and TDDFT respectively at the relaxed S_1 geometry. Our predicted kr agrees well with the experimental value, so long as the order of energy levels is correctly predicted. Evaluation of knr is less straightforward as multiple processes are involved. Our study focuses on the S_1-T_1 intersystem crossing (ISC) and the S_1-S_0 internal conversion (IC): we investigate the properties that allow us to model the knr value using a Marcus-like expression, such as the Stokes shift, the reorganization energy, and the S_1-T_1 and S_1-S_0 energy gaps. Taking these factors into consideration, we compare our results with those obtained using the actual Marcus theory and provide explanation for discrepancy. T. Kowalczyk, T. Tsuchimochi, L. Top, P.-T. Chen, and T. Van Voorhis, J. Chem. Phys., 138, 164101 (2013). M. Kasha, Discuss. Faraday Soc., 9, 14 (1950).

An experimental comparison of the Marcus-Hush and Butler-Volmer descriptions of electrode kinetics applied to cyclic voltammetry. The one electron reductions of europium (III) and 2-methyl-2-nitropropane studied at a mercury microhemisphere electrode

NASA Astrophysics Data System (ADS)

Henstridge, Martin C.; Wang, Yijun; Limon-Petersen, Juan G.; Laborda, Eduardo; Compton, Richard G.

2011-11-01

We present a comparative experimental evaluation of the Butler-Volmer and Marcus-Hush models using cyclic voltammetry at a microelectrode. Numerical simulations are used to fit experimental voltammetry of the one electron reductions of europium (III) and 2-methyl-2-nitropropane, in water and acetonitrile, respectively, at a mercury microhemisphere electrode. For Eu (III) very accurate fits to experiment were obtained over a wide range of scan rates using Butler-Volmer kinetics, whereas the Marcus-Hush model was less accurate. The reduction of 2-methyl-2-nitropropane was well simulated by both models, however Marcus-Hush required a reorganisation energy lower than expected.

Study on paddy rice yield estimation based on multisource data and the Grey system theory

NASA Astrophysics Data System (ADS)

Deng, Wensheng; Wang, Wei; Liu, Hai; Li, Chen; Ge, Yimin; Zheng, Xianghua

2009-10-01

The paddy rice is our important crops. In study of the paddy rice yield estimation, compared with the scholars who usually only take the remote sensing data or meteorology as the influence factors, we combine the remote sensing and the meteorological data to make the monitoring result closer reality. Although the gray system theory has used in many aspects, it is applied very little in paddy rice yield estimation. This study introduces it to the paddy rice yield estimation, and makes the yield estimation model. This can resolve small data sets problem that can not be solved by deterministic model. It selects some regions in Jianghan plain for the study area. The data includes multi-temporal remote sensing image, meteorological and statistic data. The remote sensing data is the 16-day composite images (250-m spatial resolution) of MODIS. The meteorological data includes monthly average temperature, sunshine duration and rain fall amount. The statistical data is the long-term paddy rice yield of the study area. Firstly, it extracts the paddy rice planting area from the multi-temporal MODIS images with the help of GIS and RS. Then taking the paddy rice yield as the reference sequence, MODIS data and meteorological data as the comparative sequence, computing the gray correlative coefficient, it selects the yield estimation factor based on the grey system theory. Finally, using the factors, it establishes the yield estimation model and does the result test. The result indicated that the method is feasible and the conclusion is credible. It can provide the scientific method and reference value to carry on the region paddy rice remote sensing estimation.

The effect of the external medium on the gravitropic curvature of rice (Oryza sativa, Poaceae) roots

NASA Technical Reports Server (NTRS)

Staves, M. P.; Wayne, R.; Leopold, A. C.

1997-01-01

The roots of rice seedlings, growing in artificial pond water, exhibit robust gravitropic curvature when placed perpendicular to the vector of gravity. To determine whether the statolith theory (in which intracellular sedimenting particles are responsible for gravity sensing) or the gravitational pressure theory (in which the entire protoplast acts as the gravity sensor) best accounts for gravity sensing in rice roots, we changed the physical properties of the external medium with impermeant solutes and examined the effect on gravitropism. As the density of the external medium is increased, the rate of gravitropic curvature decreases. The decrease in the rate of gravicurvature cannot be attributed to an inhibition of growth, since rice roots grown in 100 Osm/m3 (0.248 MPa) solutions of different densities all support the same root growth rate but inhibit gravicurvature increasingly with increasing density. By contrast, the sedimentation rate of amyloplasts in the columella cells is unaffected by the external density. These results are consistent with the gravitational pressure theory of gravity sensing, but cannot be explained by the statolith theory.

Interactions of NO{sub 2}{sup {minus}} and SO{sub 3}{sup 2{minus}} with organic triplets. Charge transfer versus energy transfer: The role of reorganization energy in triplet-anion interactions and spectroscopic methods for its evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loeff, I.; Treinin, A.; Linschitz, H.

1992-06-25

Charge-transfer (CT) and energy-transfer (NT) interactions of simple anions with organic triplets are reviewed and discussed in connection with new quenching rate constant (K{sub q}) and radical yield measurements for SO{sub 3}{sup 2{minus}} and No{sub 2}{sup {minus}}. In the latter case both processes may occur at high organic triplet energies. Reorganization energies for one-electron oxidations are obtained for several anions, using data on charge-transfer-to-solvent (CTTS) spectra and photoelectron emission thresholds, which like the kinetic parameters of Marcus-Hush theory, also reflect Franck-Condon strains. The results, combined with thermodynamic free energies, give vertical redox potentials which correlate better than do equilibrium potentialsmore » with quenching rates. The theoretical basis for correlation between k{sub q} and Hv{sub CTTS} is discussed in the framework of Marcus rate theory. Assigning the total reorganization energy in the CT quenching reaction to the small anion component of the D-A pair gives reasonable agreement with data on quenching of dye triplets but too slow rates for aryl carbonyl triplets where exciplex formation may possibly occur. The optical reorganization energy for NO{sub 2}{sup {minus}} leads to values of the thermal self-exchange rate agreeing with those computed from the Marcus-Hush cross-relations, which also neglect bonding effects. The mechanism of NO{sub 2}{sup {minus}} interaction with triplets is discussed in detail, including indirect kinetic evidence for quenching of a short-lived exciplex by NO{sub 2}{sup {minus}} without radical formation. The possibility of reduction by triplet NO{sub 2}{sup {minus}} formed by initial NT from the organic triplet is also considered. Finally, a scheme is presented involving an equilibrium between CT and NT states and relating the free energy difference between these states to radical yields. 54 refs., 8 figs., 3 tabs.« less

Calculated momentum dependence of Zhang-Rice states in transition metal oxides.

PubMed

Yin, Quan; Gordienko, Alexey; Wan, Xiangang; Savrasov, Sergey Y

2008-02-15

Using a combination of local density functional theory and cluster exact diagonalization based dynamical mean field theory, we calculate many-body electronic structures of several Mott insulating oxides including undoped high T(c) materials. The dispersions of the lowest occupied electronic states are associated with the Zhang-Rice singlets in cuprates and with doublets, triplets, quadruplets, and quintets in more general cases. Our results agree with angle resolved photoemission experiments including the decrease of the spectral weight of the Zhang-Rice band as it approaches k=0.

Thermal dissociation and relaxation in vinyl fluoride, 1,1-difluoroethane and 1,3,5-triazine

NASA Astrophysics Data System (ADS)

Xu, Hui

This study reports measurements of the thermal dissociation of 1,1-difluoroethane in the shock tube. The experiments employ laser schlieren measurements of rate for the dominant HF elimination using 10% 1,1-difluoroethane in Kr over 1500--2000 K and 43 < P < 424 torr. The product vinyl then dissociates affecting the late density gradient. We include a laser schlieren study (1717--2332 K, 75 < P < 482 torr in 10% and 4% vinyl fluoride in Kr) of this dissociation. This latter work also includes a set of experiments using shock-tube time-of-flight mass-spectrometry (4% vinyl fluoride in neon, 1500--1980 K, 500 < P < 1300 torr), which confirm the theoretical expectation that the only reaction in vinyl fluoride is HF elimination. The relaxation experiments (1--20% C2H3F in Kr, 415--1975 K, 5 < P < 50 torr, and 2% and 5% C2H4F2 in Kr, 700--1350 K, 6 < P < 22 torr) exhibit very rapid relaxation, and incubation delays should be negligible in dissociation. A RRKM model of dissociation in 1,1-difluoroethane based on a G3B3 calculation of barrier and other properties fits the experiments but requires a very large down of 1600cm-1 . Dissociation of vinyl fluoride has two parallel HF eliminations both three-center and four-center with nearly equal barriers. An RRKM fit to the observed falloff again requires an unusually large down and the experiments actually support a slightly reduced barrier. Both 1,3,5-triazine and pyrazine relax extremely rapidly with energy transfer in a few collisions, any incubation delay can be confidently discounted in dissociation. 1,3,5-triazine dissociation experiments show fall-off with a clear pressure dependence. The three body product dissociation mechanism models this dissociation perfectly. Experimental data agree well with an RRKM calculation using a down of 1200cm-1 and a barrier E0 = 84.66 kcal/mol. Dyakov et al. suggested lower barrier of E0 = 81 kcal/mole. The new RRKM calculation using this barrier seems a better fit to the experiments. The falloff is now fit well with a down of the more usual form 126(T/298) 0-9 cm-1.

A new feature in the internal heavy isotope distribution in ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharya, S. K., E-mail: skbhatta1@gmail.com; Liang, Mao-Chang; Savarino, Joel

Ozone produced by discharge or photolysis of oxygen has unusually heavy isotopic composition ({sup 18}O/{sup 16}O and {sup 17}O/{sup 16}O ratio) which does not follow normal mass fractionation rule: δ{sup 17}O ∼ 0.52{sup *}δ{sup 18}O, expressed as an anomaly Δ{sup 17}O = δ{sup 17}O − 0.52{sup *}δ{sup 18}O. Ozone molecule being an open isosceles triangle can have the heavy isotope located either in its apex or symmetric (s) position or the base or asymmetric (as) position. Correspondingly, one can define positional isotopic enrichment, written as δ{sup 18}O (s) or δ{sup 18}O (as) (and similarly for δ{sup 17}O) as well asmore » position dependent isotope anomaly Δ{sup 17}O (s) and Δ{sup 17}O (as). Marcus and co-workers have proposed a semi-empirical model based in principle on the RRKM model of uni-molecular dissociation but with slight modification (departure from statistical randomness assumption for symmetrical molecules) which explains many features of ozone isotopic enrichment. This model predicts that the bulk isotope anomaly is contained wholly in the asymmetric position and the Δ{sup 17}O (s) is zero. Consequently, Δ{sup 17}O (as) = 1.5 {sup *} Δ{sup 17}O (bulk) (named here simply as the “1.5 rule”) which has been experimentally confirmed over a range of isotopic enrichment. We now show that a critical re-analysis of the earlier experimental data demonstrates a small but significant departure from this 1.5 rule at the highest and lowest levels of enrichments. This departure provides the first experimental proof that the dynamics of ozone formation differs from a statistical model constrained only by restriction of symmetry. We speculate over some possible causes for the departure.« less

Influence of electric field on interwell tunneling rate in quasi two dimensional organic quantum wells

NASA Astrophysics Data System (ADS)

Donovan, K. J.; Elliott, J. E.; Jeong, I. S.; Scott, K.; Wilson, E. G.

2000-11-01

The tunneling rate of photocreated charge carriers between layers in Langmuir-Blodgett multilayer structures is measured indirectly using the novel technique of bimolecular recombination quenching. The tunneling rate is demonstrated to be dependent upon the applied electrostatic potential difference between the layers. This dependence is explored in light of the Marcus theory of charge transfer. That theory was developed to describe redox reactions where the driving force is supplied by a chemical potential difference between two chemically different parts of a more complex system. In the current work the electrostatic potential replaces the chemical potential as the driving potential. The field dependence of the exciton dissociation probability is also determined.

A new calibration of the semi-empirical photometric theory for Halley and other comets

NASA Technical Reports Server (NTRS)

Newburn, R. L., Jr.

1984-01-01

The semiempirical photometric theory of gas and dust production in comets (Newburn, 1979, 1981, and 1982) is recalibrated on the basis of the 17-comet compilation of spectrophotometric data of Newburn and Spinrad (1984). The results are presented in graphs and tables, and it is shown that no corrections are required for the constant R and the function delta, but that the mixing ratios (obtained as functions of heliocentric distance) can be improved, with implications for the visual-photometric comet model. Recently calculated light curves for comet Halley are compared, and the use of the nearly identical curves of Bortle and Morris (1984) and Marcus (1983) is recommended.

Ligand reorganization and activation energies in nonadiabatic electron transfer reactions

NASA Astrophysics Data System (ADS)

Zhu, Jianjun; Wang, Jianji; Stell, George

2006-10-01

The activation energy and ligand reorganization energy for nonadiabatic electron transfer reactions in chemical and biological systems are investigated in this paper. The free energy surfaces and the activation energy are derived exactly in the general case in which the ligand vibration frequencies are not equal. The activation energy is derived by free energy minimization at the transition state. Our formulation leads to the Marcus-Hush [J. Chem. Phys. 24, 979 (1956); 98, 7170 (1994); 28, 962 (1958)] results in the equal-frequency limit and also generalizes the Marcus-Sumi [J. Chem. Phys. 84, 4894 (1986)] model in the context of studying the solvent dynamic effect on electron transfer reactions. It is found that when the ligand vibration frequencies are different, the activation energy derived from the Marcus-Hush formula deviates by 5%-10% from the exact value. If the reduced reorganization energy approximation is introduced in the Marcus-Hush formula, the result is almost exact.

The role of fearless dominance in differentiating psychopathy from antisocial personality disorder: comment on Marcus, Fulton, and Edens.

PubMed

Patrick, Christopher J; Venables, Noah C; Drislane, Laura E

2013-01-01

Comments on the original article by Marcus et al. (see record 2011-23134-001). Based on their meta-analytic review of the correlates of the two factors of the Psychopathic Personality Inventory (PPI), Fearless Dominance (FD) and Self-Centered Impulsivity (SCI), Marcus, Fulton, and Edens (this issue, pp. 70-79) raise important questions about the role of FD in diagnostic conceptualizations of psychopathy. In considering their findings, general limitations of metaanalyses (e.g., Ioannidis & Lau, 1999) should be borne in mind, along with specific limitations of their analysis. These limitations are discussed here.

Stalking Higher Energy Conformers on the Potential Energy Surface of Charged Species.

PubMed

Brites, Vincent; Cimas, Alvaro; Spezia, Riccardo; Sieffert, Nicolas; Lisy, James M; Gaigeot, Marie-Pierre

2015-03-10

Combined theoretical DFT-MD and RRKM methodologies and experimental spectroscopic infrared predissociation (IRPD) strategies to map potential energy surfaces (PES) of complex ionic clusters are presented, providing lowest and high energy conformers, thresholds to isomerization, and cluster formation pathways. We believe this association not only represents a significant advance in the field of mapping minima and transition states on the PES but also directly measures dynamical pathways for the formation of structural conformers and isomers. Pathways are unraveled over picosecond (DFT-MD) and microsecond (RRKM) time scales while changing the amount of internal energy is experimentally achieved by changing the loss channel for the IRPD measurements, thus directly probing different kinetic and isomerization pathways. Demonstration is provided for Li(+)(H2O)3,4 ionic clusters. Nonstatistical formation of these ionic clusters by both direct and cascade processes, involving isomerization processes that can lead to trapping of high energy conformers along the paths due to evaporative cooling, has been unraveled.

Does Marcus-Hush theory really work Optical studies of intervalence transfer in acetylene-bridged biferrocene monocation at infinite dilution and at finite ionic strengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blackbourn, R.L.; Hupp, J.T.

1990-03-08

Intervalence charge-transfer data for acetylene-bridged biferrocene monocation (Bf{sup +}) have been collected in five solvents in the presence and absence of excess electrolyte and in the limit of infinite chromophore dilution. The study was motivated by earlier work which demonstrated that the intervalence absorption maximum for Bf{sup +} in methylene chloride could vary substantially with both chromophore concentration and added electrolyte concentration. In the present study similar (but smaller) variations are found in other solvents.

Distal [FeS]-Cluster Coordination in [NiFe]-Hydrogenase Facilitates Intermolecular Electron Transfer

PubMed Central

Petrenko, Alexander; Stein, Matthias

2017-01-01

Biohydrogen is a versatile energy carrier for the generation of electric energy from renewable sources. Hydrogenases can be used in enzymatic fuel cells to oxidize dihydrogen. The rate of electron transfer (ET) at the anodic side between the [NiFe]-hydrogenase enzyme distal iron–sulfur cluster and the electrode surface can be described by the Marcus equation. All parameters for the Marcus equation are accessible from Density Functional Theory (DFT) calculations. The distal cubane FeS-cluster has a three-cysteine and one-histidine coordination [Fe4S4](His)(Cys)3 first ligation sphere. The reorganization energy (inner- and outer-sphere) is almost unchanged upon a histidine-to-cysteine substitution. Differences in rates of electron transfer between the wild-type enzyme and an all-cysteine mutant can be rationalized by a diminished electronic coupling between the donor and acceptor molecules in the [Fe4S4](Cys)4 case. The fast and efficient electron transfer from the distal iron–sulfur cluster is realized by a fine-tuned protein environment, which facilitates the flow of electrons. This study enables the design and control of electron transfer rates and pathways by protein engineering. PMID:28067774

On Marcuse and Caring in Education

ERIC Educational Resources Information Center

Shel, Tammy

2006-01-01

Can caring and standardized testing coincide? Marcuse criticized the misuse of science because it also legitimizes social and economic hierarchy. By the same token, scholars develop standardized testing, claiming these tests are scientific and can measure objectively individuals' learning and intelligence capabilities. However, if inclusive caring…

Ligand reorganization and activation energies in nonadiabatic electron transfer reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Jianjun; Wang Jianji; Stell, George

2006-10-28

The activation energy and ligand reorganization energy for nonadiabatic electron transfer reactions in chemical and biological systems are investigated in this paper. The free energy surfaces and the activation energy are derived exactly in the general case in which the ligand vibration frequencies are not equal. The activation energy is derived by free energy minimization at the transition state. Our formulation leads to the Marcus-Hush [J. Chem. Phys. 24, 979 (1956); 98, 7170 (1994); 28, 962 (1958)] results in the equal-frequency limit and also generalizes the Marcus-Sumi [J. Chem. Phys. 84, 4894 (1986)] model in the context of studying themore » solvent dynamic effect on electron transfer reactions. It is found that when the ligand vibration frequencies are different, the activation energy derived from the Marcus-Hush formula deviates by 5%-10% from the exact value. If the reduced reorganization energy approximation is introduced in the Marcus-Hush formula, the result is almost exact.« less

The Secret of the Winning Streak

ERIC Educational Resources Information Center

Woolley, Thomas E.; du Sautoy, Marcus P. F.

2011-01-01

In 2006, Marcus du Sautoy delivered the Royal Institution Christmas Lectures on the subject of mathematics. From this, a workshop was created using ideas illustrated in the programme. A group of mathematical students from the University of Oxford, known as Marcus' Marvellous Mathemagicians, were trained in this workshop and now travel to schools…

Strategy, National Interests, and Means to an End

DTIC Science & Technology

2007-10-01

p. 2. 13. Codevilla and Seabury, p. 251. 22 14. Ibid., pp. 92-94. 15. Ibid. 16. Ibid., pp. 84-85. 17. Ibid., p. 85. 18. Marcus Aurelius ...nor with divergent motives. Marcus Aurelius18 Somalia’s descent into chaos is well-chronicled in several publications, so additional diagnosis of

Phonon-electron coupling and tunneling effect on charge transport in organic semi-conductor crystals of Cn-BTBT.

PubMed

Zhou, Yecheng; Deng, Wei-Qiao; Zhang, Hao-Li

2016-09-14

Cn-[1]benzothieno[3,2-b][1]-benzothiophene (BTBT) crystals show very high hole mobilities in experiments. These high mobilities are beyond existing theory prediction. Here, we employed different quantum chemistry methods to investigate charge transfer in Cn-BTBT crystals and tried to find out the reasons for the underestimation in the theory. It was found that the hopping rate estimated by the Fermi Golden Rule is higher than that of the Marcus theory due to the high temperature approximation and failure at the classic limit. More importantly, molecular dynamics simulations revealed that the phonon induced fluctuation of electronic transfer integral is much larger than the average of the electronic transfer integral itself. Mobilities become higher if simulations implement the phonon-electron coupling. This conclusion indicates that the phonon-electron coupling promotes charge transfer in organic semi-conductors at room temperature.

Phonon-electron coupling and tunneling effect on charge transport in organic semi-conductor crystals of Cn-BTBT

NASA Astrophysics Data System (ADS)

Zhou, Yecheng; Deng, Wei-Qiao; Zhang, Hao-Li

2016-09-01

Cn-[1]benzothieno[3,2-b][1]-benzothiophene (BTBT) crystals show very high hole mobilities in experiments. These high mobilities are beyond existing theory prediction. Here, we employed different quantum chemistry methods to investigate charge transfer in Cn-BTBT crystals and tried to find out the reasons for the underestimation in the theory. It was found that the hopping rate estimated by the Fermi Golden Rule is higher than that of the Marcus theory due to the high temperature approximation and failure at the classic limit. More importantly, molecular dynamics simulations revealed that the phonon induced fluctuation of electronic transfer integral is much larger than the average of the electronic transfer integral itself. Mobilities become higher if simulations implement the phonon-electron coupling. This conclusion indicates that the phonon-electron coupling promotes charge transfer in organic semi-conductors at room temperature.

Contact/Disability Performance. An Essay Constructed between Petra Kuppers and Neil Marcus

ERIC Educational Resources Information Center

Kuppers, Petra; Marcus, Neil

2009-01-01

This dialogue discusses disability and performance through poetic interrogation, interspersed with segments of Neil Marcus's play "My Sexual History." The authors touch on such topics such as sexuality and representation, dance and theatre, the management of disability staring, speech difference and writing, curiosity and shrouding. (Contains 1…

Reassessing Subjectivity, Criticality, and Inclusivity: Marcuse's Challenge to Adult Education.

ERIC Educational Resources Information Center

Brookfield, Stephen

2002-01-01

Although Herbert Marcuse did not write as an adult educator, his analysis of subjectivity, criticality, and inclusivity has implications for adult education. He demonstrated how apparently humanistic tolerance for diversity can be manipulated to reinforce dominant ideology, and he made a case for aesthetic education as a site for critical…

Dust Acoustic Wave Excitation in a Plasma with Warm Dust

NASA Astrophysics Data System (ADS)

Rosenberg, M.; Thomas, E., Jr.; Marcus, L.; Fisher, R.; Williams, J. D.; Merlino, R. L.

2008-11-01

Measurements of the dust acoustic wave dispersion relation in dusty plasmas formed in glow discharges at the University of Iowa [1] and Auburn University [2] have shown the importance of finite dust temperature effects. The effect of dust grains with large thermal speeds was taken into account using kinetic theory of the ion-dust streaming instability [3]. The results of analytic and numerical calculations of the dispersion relation based on the kinetic theory will be presented and compared with the experimental results. [1] E. Thomas, Jr., R. Fisher, and R. L. Merlino, Phys. Plasmas 14, 123701 (2007). [2] J. D. Williams, E. Thomas Jr., and L. Marcus, Phys. Plasmas 15, 043704 (2008). [3] M. Rosenberg, E. Thomas Jr., and R. L. Merlino, Phys. Plasmas 15, 073701 (2008).

Three-dimensional representations of photo-induced electron transfer rates in pyrene-(CH2)n-N,N'-dimethylaniline systems obtained by three electron transfer theories.

PubMed

Rujkorakarn, Rong; Tanaka, Fumio

2009-01-01

The observed rates of photo-induced electron transfer (ET) from N,N'-dimethylaniline (DMA) to the excited pyrene (Py) in confined systems of pyrene-(CH(2))(n)-N,N'- dimethylaniline (PnD: n=1-3) were studied by molecular dynamic simulation (MD) and three kinds of electron transfer theories. ET parameters contained in Marcus theory (M theory), Bixon and Jortner theory (BJ theory) and Kakitani and Mataga theory (KM theory) were determined so as to fit the calculated fluorescence intensities with those obtained by the observed ET rates, according to a non-linear least squares method. Three-dimensional profiles of logarithm of calculated ET rates depending on two of three ET parameters, R, epsilon(0) and -DeltaG degrees were systematically examined with best-fit ET parameters of P1D. Bell shape dependencies of ET rate were predicted on R and on epsilon(0), and on -DeltaG degrees as well, by M theory and KM theory. The profiles of logarithm of ET rate calculated by BJ theory exhibited oscillatory dependencies not only on -DeltaG degrees , but also on R and on epsilon(0). Relationship between ET state and charge transfer complex was discussed with BJ theory.

Anomalously large effects of pressure on electron transfer kinetics in solution: The aqueous manganate(VI)-permanganate(VII) system

NASA Astrophysics Data System (ADS)

Swaddle, T. W.; Spiccia, L.

1986-05-01

The classical Stranks-Hush-Marcus theory of pressure effects on the rates of outer-sphere electron transfer reaction rates in solution underestimates |ΔV ∗| specifically, for the MnO 4/MnO 42- (aq) exchange, ΔV ∗=-21.2 (observed) vs. -6.6 cm3mol-1 (calculated). This discrepancy can best be resolved by conceding that the Mn-Mn separation σ in the transition state is variable and pressure-sensitive in the context of non-adiabatic electron transfer within an ellipsoidal cavity with σ ∼ 550 pm.

Psychoanalysis and the community mental health movement.

PubMed

Croghan, L M

1975-01-01

Psychoanalysis and CMHM were once enemies. Psychoanalysis has made noteworthy advances toward the CMHM idea both in technique changes and in community involvement. It is possible that CMHM may finally reject all psychoanalytic contribution and face its future without a theory. If that takes place, the CMHM some day in its future may turn a corner and find itself face to face with the lonely, individual man, conscious of his past and fearful of the unexplained anxiety within him. It is then that the CMHM will find itself once again studying the works of Herbert Marcuse, Erik Erikson, Sigmund Freud, and the psychoanalytic world.

Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bao, Junwei Lucas; Zheng, Jingjing; Truhlar, Donald G.

Here, pressure-dependent reactions are ubiquitous in combustion and atmospheric chemistry. We employ a new calibration procedure for quantum Rice–Ramsperger–Kassel (QRRK) unimolecular rate theory within a chemical activation mechanism to calculate the pressure-falloff effect of a radical association with an aromatic ring. The new theoretical framework is applied to the reaction of H with toluene, which is a prototypical reaction in the combustion chemistry of aromatic hydrocarbons present in most fuels. Both the hydrogen abstraction reactions and the hydrogen addition reactions are calculated. Our system-specific (SS) QRRK approach is adjusted with SS parameters to agree with multistructural canonical variational transition statemore » theory with multidimensional tunneling (MS-CVT/SCT) at the high-pressure limit. The new method avoids the need for the usual empirical estimations of the QRRK parameters, and it eliminates the need for variational transition state theory calculations as a function of energy, although in this first application we do validate the falloff curves by comparing SS-QRRK results without tunneling to multistructural microcanonical variational transition state theory (MS-μVT) rate constants without tunneling. At low temperatures, the two approaches agree well with each other, but at high temperatures, SS-QRRK tends to overestimate falloff slightly. We also show that the variational effect is important in computing the energy-resolved rate constants. Multiple-structure anharmonicity, torsional–potential anharmonicity, and high-frequency-mode vibrational anharmonicity are all included in the rate computations, and torsional anharmonicity effects on the density of states are investigated. Branching fractions, which are both temperature- and pressure-dependent (and for which only limited data is available from experiment), are predicted as a function of pressure.« less

Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory

DOE PAGES

Bao, Junwei Lucas; Zheng, Jingjing; Truhlar, Donald G.

2016-02-03

Here, pressure-dependent reactions are ubiquitous in combustion and atmospheric chemistry. We employ a new calibration procedure for quantum Rice–Ramsperger–Kassel (QRRK) unimolecular rate theory within a chemical activation mechanism to calculate the pressure-falloff effect of a radical association with an aromatic ring. The new theoretical framework is applied to the reaction of H with toluene, which is a prototypical reaction in the combustion chemistry of aromatic hydrocarbons present in most fuels. Both the hydrogen abstraction reactions and the hydrogen addition reactions are calculated. Our system-specific (SS) QRRK approach is adjusted with SS parameters to agree with multistructural canonical variational transition statemore » theory with multidimensional tunneling (MS-CVT/SCT) at the high-pressure limit. The new method avoids the need for the usual empirical estimations of the QRRK parameters, and it eliminates the need for variational transition state theory calculations as a function of energy, although in this first application we do validate the falloff curves by comparing SS-QRRK results without tunneling to multistructural microcanonical variational transition state theory (MS-μVT) rate constants without tunneling. At low temperatures, the two approaches agree well with each other, but at high temperatures, SS-QRRK tends to overestimate falloff slightly. We also show that the variational effect is important in computing the energy-resolved rate constants. Multiple-structure anharmonicity, torsional–potential anharmonicity, and high-frequency-mode vibrational anharmonicity are all included in the rate computations, and torsional anharmonicity effects on the density of states are investigated. Branching fractions, which are both temperature- and pressure-dependent (and for which only limited data is available from experiment), are predicted as a function of pressure.« less

Time-Resolved Kinetic Chirped-Pulse Rotational Spectroscopy in a Room-Temperature Flow Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaleski, Daniel P.; Harding, Lawrence B.; Klippenstein, Stephen J.

Chirped-pulse Fourier transform millimeter-wave spectroscopy is a potentially powerful tool for studying chemical reaction dynamics and kinetics. Branching ratios of multiple reaction products and intermediates can be measured with unprecedented chemical specificity; molecular isomers, conformers, and vibrational states have distinct rotational spectra. Here we demonstrate chirped-pulse spectroscopy of vinyl cyanide photoproducts in a flow tube reactor at ambient temperature of 295 K and pressures of 1-10 mu bar. This in situ and time-resolved experiment illustrates the utility of this novel approach to investigating chemical reaction dynamics and kinetics. Following 193 nm photodissociation of CH2CHCN, we observe rotational relaxation of energizedmore » HCN, HNC, and HCCCN photoproducts with 10 mu s time resolution and sample the vibrational population distribution of HCCCN. The experimental branching ratio HCN/HCCCN is compared with a model based on RRKM theory using high-level ab initio calculations, which were in turn validated by comparisons to Active Thermochemical Tables enthalpies.« less

Time-Resolved Kinetic Chirped-Pulse Rotational Spectroscopy in a Room-Temperature Flow Reactor

DOE PAGES

Zaleski, Daniel P.; Harding, Lawrence B.; Klippenstein, Stephen J.; ...

2017-12-01

Chirped-pulse Fourier transform millimeter-wave spectroscopy is a potentially powerful tool for studying chemical reaction dynamics and kinetics. Branching ratios of multiple reaction products and intermediates can be measured with unprecedented chemical specificity; molecular isomers, conformers, and vibrational states have distinct rotational spectra. Here we demonstrate chirped-pulse spectroscopy of vinyl cyanide photoproducts in a flow tube reactor at ambient temperature of 295 K and pressures of 1-10 mu bar. This in situ and time-resolved experiment illustrates the utility of this novel approach to investigating chemical reaction dynamics and kinetics. Following 193 nm photodissociation of CH2CHCN, we observe rotational relaxation of energizedmore » HCN, HNC, and HCCCN photoproducts with 10 mu s time resolution and sample the vibrational population distribution of HCCCN. The experimental branching ratio HCN/HCCCN is compared with a model based on RRKM theory using high-level ab initio calculations, which were in turn validated by comparisons to Active Thermochemical Tables enthalpies.« less

Conformer lifetimes of ethyl cyanoformate from exchange-averaged rotational spectra.

PubMed

True, Nancy S

2009-06-25

Ethyl cyanoformate exists as a mixture of two conformers but displays three R-branch a-type band series in its rotational spectrum. Simulations with population fractions 0.37 at 210 K and 0.70 at 297 K undergoing conformer exchange with average conformer lifetimes, , shorter than approximately 40 ps at approximately 210 K and shorter than approximately 37 ps at 297 K reproduce the experimental spectra between 26.5 and 38 GHz, the exchanging species accounting for the third set of bands. The upper-limit 's are 1 order of magnitude longer than RRKM theory predictions and the population fractions are consistent with the total population with energy above 700 cm(-1), approximately twice the conformer interconversion barrier height. Model calculations indicate that extensive K-sublevel mixing in individual molecular eigenstates can produce the large population and the narrow distribution of the rotational-constant sum, B + C, consistent with the observed exchange-averaged band series.

A Dense Corpus Study of Past Tense and Plural Overregularization in English.

ERIC Educational Resources Information Center

Maslen, Robert J.C.; Theakson, Anna L.; Lieven, Elena V.M.; Tomasello, Michael

2004-01-01

In the "blocking-and-retrieval-failure" account of overregularization (OR; G. F. Marcus, 1995; G. F. Marcus et al., 1992), the claim that a symbolic rule generates regular inflection is founded on pervasively low past tense OR rates and the lack of a substantive difference between past tense and plural OR rates. Evidence of extended periods of OR…

Thanatos and Civilization: Lacan, Marcuse, and the Death Drive

ERIC Educational Resources Information Center

Cho, Daniel

2006-01-01

During the 1950s and 1960s two thinkers, Herbert Marcuse and Jacques Lacan, were conducting a "return to Freud" for very similar reasons. If the differences between them are often advertised, their affinities are less so. In this article, I examine how their "return to Freud" and fidelity to psychoanalysis serves as a common ground to read each in…

Performance analysis and simulation of vertical gallium nitride nanowire transistors

NASA Astrophysics Data System (ADS)

Witzigmann, Bernd; Yu, Feng; Frank, Kristian; Strempel, Klaas; Fatahilah, Muhammad Fahlesa; Schumacher, Hans Werner; Wasisto, Hutomo Suryo; Römer, Friedhard; Waag, Andreas

2018-06-01

Gallium nitride (GaN) nanowire transistors are analyzed using hydrodynamic simulation. Both p-body and n-body devices are compared in terms of threshold voltage, saturation behavior and transconductance. The calculations are calibrated using experimental data. The threshold voltage can be tuned from enhancement to depletion mode with wire doping. Surface states cause a shift of threshold voltage and saturation current. The saturation current depends on the gate design, with a composite gate acting as field plate in the p-body device. He joined Bell Laboratories, Murray Hill, NJ, as a Technical Staff Member. In October 2001, he joined the Optical Access and Transport Division, Agere Systems, Alhambra, CA. In 2004, he was appointed an Assistant Professor at ETH Zurich,. Since 2008, at the University of Kassel, Kassel, Germany, and he has been a Professor the Head of the Computational Electronics and Photonics Group, and co-director of CINSaT since 2010. His research interests include computational optoelectronics, process and device design of semiconductor photonic devices, microwave components, and electromagnetics modeling for nanophotonics. Dr. Witzigmann is a senior member of the SPIE and IEEE.

77 FR 46125 - Sunoco, Inc., R&M, Refining Division, Marcus Hook, PA; Sunoco, Inc., 10 Industrial Hwy., MS4...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-02

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-81,145; TA-W-81,145A] Sunoco, Inc., R&M, Refining Division, Marcus Hook, PA; Sunoco, Inc., 10 Industrial Hwy., MS4 Building G, Lester, PA; Notice of Negative Determination on Reconsideration On April 30, 2012, the Department of Labor issued an Affirmative Determination Regarding...

77 FR 29362 - Sunoco, Inc., R&M Refining Division, Marcus Hook, PA; Sunoco, Inc., 10 Industrial Hwy, MS4...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-17

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-81,145; TA-W-81,145A] Sunoco, Inc., R&M Refining Division, Marcus Hook, PA; Sunoco, Inc., 10 Industrial Hwy, MS4 Building G, Lester, PA; Notice of Affirmative Determination Regarding Application for Reconsideration By application dated March 26, 2012, the United Steel Workers Union...

Political Authoritarianism and Economic Success in Indonesia and South Korea

DTIC Science & Technology

2017-06-01

ECONOMIC SUCCESS IN INDONESIA AND SOUTH KOREA by Marcus A. Johnson June 2017 Thesis Advisor: Naazneen Barma Second Reader: Robert Weiner THIS PAGE...4. TITLE AND SUBTITLE POLITICAL AUTHORITARIANISM AND ECONOMIC SUCCESS IN INDONESIA AND SOUTH KOREA 5. FUNDING NUMBERS 6. AUTHOR(S) Marcus A...CODE 13. ABSTRACT (maximum 200 words) This thesis researches the features of political authoritarianism that might contribute to economic success

An Assessment of Nonresponse Bias in Mail Surveys of Naval Personnel

DTIC Science & Technology

1976-02-01

Hollowell, Ida Harloff, and Marge Covher. Special thanks are due to Jim Herbert who spent many hours keep- ing track of cases, tabulating, and...volunteering for psychological experiments has revealed that the type of experiment (Martin & Marcuse , 1958), the alterna- tives to participating...M., & Marcuse , F. L. Characteristics of volunteers and nonvol- unteers in psychological experimentation. Journal of Consulting Psychology, 1958

[Study on the mechanism of liesegang pattern development during carbonating of traditional sticky rice-lime mortar].

PubMed

Wei, Guo-feng; Fang, Shi-qiang; Zhang, Bing-jian; Wang, Xiao-qi; Li, Zu-guang

2012-08-01

Liesegang patterns in traditional sticky rice-lime mortar undergoing carbonation were investigated by means of FTIR, XRD and SEM. Results indicate that well-developed Liesegang patterns only occur in the mortar prepared with aged lime and sticky rice. The smaller Ca(OH)2 particle size in aged lime and the control of the sticky rice for the crystallization of calcium carbonate lead to the small pores in this mortar. These small pores can make Ca2+ and CO3(2-) highly supersaturated, which explains the reason why Liesegang pattern developed in the sticky rice-aged lime mortar. The formed metastable aragonite proves that Liesegang pattern could be explained based on the post-nucleation theory.

Sex Ideologies in China: Examining Interprovince Differences.

PubMed

Hu, Yang

2016-01-01

In recent decades, premarital sex, extramarital sex, and homosexuality have become increasingly visible in China, leading scholars to claim that a national "sex revolution" is under way. However, China's internal sociocultural diversity calls this nation-level generalization into question. How do sex ideologies vary across China's distinct provinces? To what extent are interprovince variations in sex ideologies associated with distinct macrolevel social factors in China? In this research, data from the 2010 China General Social Survey and the 2011 Chinese Statistics Yearbook were analyzed using multilevel models to test four contending theories of interprovince differences in sex ideologies in China: modernization, Westernization, deindustrialization, and the "rice theory." The modernization theory was unsupported by the results, as socioeconomic development is not significantly associated with sex ideologies. Higher levels of deindustrialization and Westernization were associated with less traditional sex ideologies, but the strength of association varied across the domains of premarital sex, extramarital sex, and homosexuality. The rice theory was consistently supported, as the distinction between rice and wheat agriculture explained up to 30% of the province-level variance in sex ideologies. The findings underline the roles of both long-standing geographic differences and recent social changes in shaping China's ideational landscape of sex.

Regioselective electrochemical reduction of 2,4-dichlorobiphenyl - Distinct standard reduction potentials for carbon-chlorine bonds using convolution potential sweep voltammetry

NASA Astrophysics Data System (ADS)

Muthukrishnan, A.; Sangaranarayanan, M. V.; Boyarskiy, V. P.; Boyarskaya, I. A.

2010-04-01

The reductive cleavage of carbon-chlorine bonds in 2,4-dichlorobiphenyl (PCB-7) is investigated using the convolution potential sweep voltammetry and quantum chemical calculations. The potential dependence of the logarithmic rate constant is non-linear which indicates the validity of Marcus-Hush theory of quadratic activation-driving force relationship. The ortho-chlorine of the 2,4-dichlorobiphenyl gets reduced first as inferred from the quantum chemical calculations and bulk electrolysis. The standard reduction potentials pertaining to the ortho-chlorine of 2,4-dichlorobiphenyl and that corresponding to para chlorine of the 4-chlorobiphenyl have been estimated.

Reactions of electronically excited molecular nitrogen with H2 and H2O molecules: theoretical study

NASA Astrophysics Data System (ADS)

Pelevkin, Alexey V.; Sharipov, Alexander S.

2018-05-01

Comprehensive quantum chemical analysis with the usage of the second-order perturbation multireference XMCQDPT2 approach was carried out to study the processes in the   +  H2 and   +  H2O systems. The energetically favorable reaction pathways have been revealed based on the exploration of potential energy surfaces. It has been shown that the reactions   +  H2 and   +  H2O occur with small activation barriers and, primarily, lead to the formation of N2H  +  H and N2H  +  OH products, respectively. Further, the interaction of these species could give rise to the ground state and H2 (or H2O) products, however, the estimations, based on RRKM theory and dynamic reaction coordinate calculations, exhibited that the   +  H2 and   +  H2O reactions lead to the dissociative quenching predominately. Appropriate rate constants for revealed reaction channels have been estimated by using a canonical variational theory and capture approximation. Corresponding three-parameter Arrhenius expressions for the temperature range T  =  300  ‑  3000 K were reported.

Trait Anxiety and Salivary Cortisol During Free Living and Military Stress

DTIC Science & Technology

2008-02-01

2 x February 2008 129 RESEARCH ARTICLE Trait Anxiety and Salivary Cortisol During Free Living and Military Stress Marcus K. Taylor , Jared P...cortex to produce and re- lease glucocorticoid hormones ( 6 ). The primary glucocorticoid is cortisol, which affects many body tissues, including...publication in November 2007 . Address reprint requests to: Marcus K. Taylor, Ph.D., Naval Health Research Center, Stress Physiology Research Core, Dept

Effects of Experimental Learning--Outcomes of an Empirical Study in the Vocational Field of Structural Engineering

ERIC Educational Resources Information Center

Bünning, Frank

2013-01-01

Pedagogic approaches to TVET offer a limited range of teaching strategies which make use of experimental learning. Thus experiments were developed for teachers of structural engineering and timber processing technologies and were subject to empirical evaluation by a researcher at the Otto-von-Guericke-University Magdeburg and Kassel University.…

The Anxious and Ambivalent Partisan: The Effect of Incidental Anxiety on Partisan Motivated Recall and Ambivalence.

PubMed

Groenendyk, Eric

2016-01-01

Affective Intelligence Theory (AIT) asserts that anxiety reduces the effect of party identification on candidate preferences (Marcus, Neuman, and MacKuen 2000), but recent studies have raised doubts about this causal claim. Rather than functioning as a moderator of party identification, perhaps anxiety has a direct effect on preferences, or perhaps the relationship is reversed and preferences drive emotions (Ladd and Lenz 2008). Alternatively, Marcus et al.'s measure of anxiety may simply be capturing partisan ambivalence, so the posited relationship is spurious (Lavine, Johnston, and Steenbergen 2012). This paper addresses each of these questions by examining the effect of experimentally induced emotions on the types of considerations that came to mind when a national sample of adult Americans was asked what they liked and disliked about Barack Obama. By directly manipulating anxiety, this experiment avoids the causal ambiguity plaguing this debate and ascertains the true nature of the relationship between anxiety and ambivalence. Consistent with AIT, anxiety led respondents to recall more contemporary considerations, whereas enthusiasm brought to mind more long-standing considerations. Because the political context at the time of the study (fall 2013) was a very tumultuous time for the Obama administration, the increased accessibility of contemporary considerations led Democratic participants to experience more ambivalence in the anxiety condition. This effect was concentrated among those Democrats who were exposed to the most newspaper coverage.

The Anxious and Ambivalent Partisan

PubMed Central

Groenendyk, Eric

2016-01-01

Affective Intelligence Theory (AIT) asserts that anxiety reduces the effect of party identification on candidate preferences (Marcus, Neuman, and MacKuen 2000), but recent studies have raised doubts about this causal claim. Rather than functioning as a moderator of party identification, perhaps anxiety has a direct effect on preferences, or perhaps the relationship is reversed and preferences drive emotions (Ladd and Lenz 2008). Alternatively, Marcus et al.’s measure of anxiety may simply be capturing partisan ambivalence, so the posited relationship is spurious (Lavine, Johnston, and Steenbergen 2012). This paper addresses each of these questions by examining the effect of experimentally induced emotions on the types of considerations that came to mind when a national sample of adult Americans was asked what they liked and disliked about Barack Obama. By directly manipulating anxiety, this experiment avoids the causal ambiguity plaguing this debate and ascertains the true nature of the relationship between anxiety and ambivalence. Consistent with AIT, anxiety led respondents to recall more contemporary considerations, whereas enthusiasm brought to mind more long-standing considerations. Because the political context at the time of the study (fall 2013) was a very tumultuous time for the Obama administration, the increased accessibility of contemporary considerations led Democratic participants to experience more ambivalence in the anxiety condition. This effect was concentrated among those Democrats who were exposed to the most newspaper coverage. PMID:27274573

Optical characterization of randomly microrough surfaces covered with very thin overlayers using effective medium approximation and Rayleigh-Rice theory

NASA Astrophysics Data System (ADS)

Ohlídal, Ivan; Vohánka, Jiří; Čermák, Martin; Franta, Daniel

2017-10-01

The modification of the effective medium approximation for randomly microrough surfaces covered by very thin overlayers based on inhomogeneous fictitious layers is formulated. The numerical analysis of this modification is performed using simulated ellipsometric data calculated using the Rayleigh-Rice theory. The system used to perform this numerical analysis consists of a randomly microrough silicon single crystal surface covered with a SiO2 overlayer. A comparison to the effective medium approximation based on homogeneous fictitious layers is carried out within this numerical analysis. For ellipsometry of the system mentioned above the possibilities and limitations of both the effective medium approximation approaches are discussed. The results obtained by means of the numerical analysis are confirmed by the ellipsometric characterization of two randomly microrough silicon single crystal substrates covered with native oxide overlayers. It is shown that the effective medium approximation approaches for this system exhibit strong deficiencies compared to the Rayleigh-Rice theory. The practical consequences implied by these results are presented. The results concerning the random microroughness are verified by means of measurements performed using atomic force microscopy.

Doctors aren't immune to theft and fraud

PubMed Central

Marcus, Gary

1995-01-01

A chartered accountant says the problem of fraud within medical practices is far from rare, even though prevention is relatively simple. Gary Marcus provides advice to physicians about ways to spot fraud within their practices and things they can do to prevent it. No matter how small your practice or how long you have had the same employees, says Marcus, given the right circumstances anyone might steal from you. Imagesp940-a PMID:7697586

Environmental Assessment for Pond Target at the South Range of the Utah Test and Training Range

DTIC Science & Technology

2004-11-01

Christenson, 1988 , Shallow Ground Water and Related Hazards in Utah) Mr. Marcus Blood, the Hill AFB Natural Resources Manager, has reported a shallow...Christenson, 1988 , Shallow Ground Water and Related Hazards in Utah) Mr. Marcus Blood, the Hill AFB Natural Resources Manager, has reported a shallow...Complex Cultural Resource Inventory, Wendover Air Force Range, Tooele County, Utah, March 1999. Cronquist , A ., Holmgren, A.H., Holmgren, N.H

Moral, Ethical, and Psychological Preparation of Soldiers and Units for Combat

DTIC Science & Technology

2011-01-01

Stoic phi los o pher Marcus Aurelius ob served, “Re spect be comes con crete through em pa thy.” Cicero re - minds us that a sol dier’s re spect must...build ing trust with the pop u la tion ought to be M C M A S T E R 1 3 * Marcus Tullius Cicero, On Du ties, ed. and trans. M. T. Grif fin and E. M. Atkins

Metal cation exchange reactions of ore minerals in Fe-Mn crusts of the Marcus Wake Rise (Pacific Ocean) in aqueous-salt solutions

NASA Astrophysics Data System (ADS)

Novikov, G. V.; Bogdanova, O. Yu.; Melnikov, M. E.; Drozdova, A. N.; Lobus, N. V.; Shulga, N. A.

2017-12-01

It is shown that the reaction ability of metal cations of ore minerals in Fe-Mn crusts of the Marcus Wake Rise increases in the following manner: (Co2+ < Cu2+ < Ni2+) < (Mg2+ < Mn2+ < K+ ≈ Ca2+ ≈ Na+). The composition of the exchange complex of the ore minerals is constant and includes these metal cations. Ca2+ and Na+ are major contributors to the exchange capacity of the ore minerals. The capacity of the ore minerals by cations of alkali and base metals is 0.43-0.60 and 2.08-2.70 mg-equiv/g, respectively. The exchange capacity of the ore minerals by cations of base metals increases linearly with the increase in the MnO2 content of the crust and does not depend on the geographical locations of the Marcus Wake guyots.

A Comparative Psychobiography of Hillary Clinton and Condoleezza Rice

ERIC Educational Resources Information Center

Fitch, Trey; Marshall, Jennifer

2008-01-01

The purpose of this study was to apply psychobiography to the lives of Hillary Clinton and Condoleezza Rice. Psychobiography can be applied as a method of teaching personality theory and it can also be used as a research method. Most political personas are crafted through 20 second sound bites from the radio, Internet, and television. However, a…

Product Lifecycle Management: A Collaborative Tool for Defense Acquisitions

DTIC Science & Technology

2010-09-01

by Christopher M. Schindler September 2010 Thesis Advisor: Thomas Housel Second Reader: William Solitario Approved for public release...September 2010 Author: Christopher M. Schindler Approved by: Thomas Housel, PhD Thesis Advisor William Solitario Second Reader...Ben Kassel, Randy Langmead, Michael Schwind, and Jeff Watson. I also must thank my advisors, Thomas Housel and Bill Solitario, for guiding me

The p53-Deficient Mouse as a Breast Cancer Model

DTIC Science & Technology

1995-10-01

M.A. Gryka , F.Z. Bischoff, M.A. Tain- Halachmi, R.T. Bronson, and R.A. Weinberg. 1994. Tumor sky, and S.H. Friend. 1990. Germ line p53 mutations in a...J. Kassel, M.A. Gryka , F.Z. Bischoff, Weaver-Feldhaus, W. Ding, Z. Gholami, P. Soderkvist, L. M.A. Tainsky, and S.H. Friend. 1990. Germ line p53

Studies of the Processing of Single Words Using Positron Tomographic Measures of Cerebral Blood Flow Change.

DTIC Science & Technology

1987-01-01

BLOOD FLOW CHANGE Steven E. Petersen, Peter T. Fox, Michael I. Posner, Marcus Raichle McDonnell Center for Studies of Higher Brain Function...Single Words Using Positron Emission Tomographic Measurements of Cerebral Blood Flow Change *= ’I PERSONAL AUTHOR(S) * Petersen, Steven E. 13a. TYPE OF...CHANGE Steven E. Petersen, Peter T. Fox, Michael I. Posner, Marcus E. Raichle INTRODUCTION Language is an essential characteristic of the human

Fatigue Testing of AA7050-T7451 with Various Corrosion Prevention Surface Treatments

DTIC Science & Technology

2013-06-01

UNCLASSIFIED Authors Marcus McDonald Air Vehicles Division Marcus McDonald initially spent 3 years working in the oil & gas, steel and...treatments: caustic degreasing, de-oxidising or anodising. The pits in the anodised coupons were larger than the pits caused by the pre-IVD etching...those fatigue cracks that grew from them spent less time in growing whilst they were small, because the crack started at what was a larger effective

Effects of Strong Local Sporadic E on ELF Propagation.

DTIC Science & Technology

1978-08-15

Huygens diffraction model (e.g., Marcuse , 1972). The model is similar to that used by Crombie. Unlike Crombie’s work however , the Fresnel approximation...40. Marcuse , D., “Light transmission optics ,” Van Nostrand Reinhold Co., New York , 1972. Papper t , R. A. & Moler , W. F., “A theoretica’ study of...ATTN Donald Dubbert O1 CY ATTN Herbert Rend University of IllinoisDepartment of Electrical Engineering Develco Urbana , IL 61803 530 Logue Avenue O2CY

Modeling of hydrogen evolution reaction on the surface of GaInP2

NASA Astrophysics Data System (ADS)

Choi, Woon Ih; Wood, Brandon; Schwegler, Eric; Ogitsu, Tadashi

2012-02-01

GaInP2 is promising candidate material for hydrogen production using sunlight. It reduces solvated proton into hydrogen molecule using light-induced excited electrons in the photoelectrochemical cell. However, it is challenging to model hydrogen evolution reaction (HER) using first-principles molecular dynamics. Instead, we use Anderson-Newns model and generalized solvent coordinate in Marcus-Hush theory to describe adiabatic free energy surface of HER. Model parameters are fitted from the DFT calculations. We model Volmer-Heyrovsky reaction path on the surfaces of CuPt phase of GaInP2. We also discuss effects of surface oxide and catalyst atoms that exist on top of bare surfaces in experimental circumstances.

Kinetics of the reduction of cobalt(III) amine complexes by 1-hydroxy-1-methylethyl radicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kusaba, K.; Ogino, Hiroshi; Bakac, A.

1989-03-08

In order to better understand the rate constants for the reduction of several cobalt complexes by 1-hydroxy-1-methylene radicals ({sup {sm bullet}}C(CH{sub 3}){sub 2}OH), the reactions of {sup {sm bullet}}(CH{sub 3}){sub 2}OH with several cobalt(III) complexes of bidentate amines have been studied. The Marcus-Hush theory was deemed the most appropriate for analysis of the kinetic data. The correlation between the kinetics of the reduction of the Co(III) amines by C(CH{sub 3}){sub 2}OH and the reduction of the first d-d band for Co(III) complexes is discussed. 21 refs., 2 figs., 1 tab.

Molecular salt effects in the gas phase: tuning the kinetic basicity of [HCCLiCl]⁻ and [HCCMgCl₂]⁻ by LiCl and MgCl₂.

PubMed

Khairallah, George N; da Silva, Gabriel; O'Hair, Richard A J

2014-10-06

A combination of gas-phase ion-molecule reaction experiments and theoretical kinetic modeling is used to examine how a salt can influence the kinetic basicity of organometallates reacting with water. [HC≡CLiCl](-) reacts with water more rapidly than [HC≡CMgCl2](-), consistent with the higher reactivity of organolithium versus organomagnesium reagents. Addition of LiCl to [HC≡CLiCl](-) or [HC≡CMgCl2](-) enhances their reactivity towards water by a factor of about 2, while addition of MgCl2 to [HC≡CMgCl2](-) enhances its reactivity by a factor of about 4. Ab initio calculations coupled with master equation/RRKM theory kinetic modeling show that these reactions proceed via a mechanism involving formation of a water adduct followed by rearrangement, proton transfer, and acetylene elimination as either discrete or concerted steps. Both the energy and entropy requirements for these elementary steps need to be considered in order to explain the observed kinetics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theory and computation of non-RRKM lifetime distributions and rates in chemical systems with three or more degrees of freedom

NASA Astrophysics Data System (ADS)

Gabern, Frederic; Koon, Wang S.; Marsden, Jerrold E.; Ross, Shane D.

2005-11-01

The computation, starting from basic principles, of chemical reaction rates in realistic systems (with three or more degrees of freedom) has been a longstanding goal of the chemistry community. Our current work, which merges tube dynamics with Monte Carlo methods provides some key theoretical and computational tools for achieving this goal. We use basic tools of dynamical systems theory, merging the ideas of Koon et al. [W.S. Koon, M.W. Lo, J.E. Marsden, S.D. Ross, Heteroclinic connections between periodic orbits and resonance transitions in celestial mechanics, Chaos 10 (2000) 427-469.] and De Leon et al. [N. De Leon, M.A. Mehta, R.Q. Topper, Cylindrical manifolds in phase space as mediators of chemical reaction dynamics and kinetics. I. Theory, J. Chem. Phys. 94 (1991) 8310-8328.], particularly the use of invariant manifold tubes that mediate the reaction, into a tool for the computation of lifetime distributions and rates of chemical reactions and scattering phenomena, even in systems that exhibit non-statistical behavior. Previously, the main problem with the application of tube dynamics has been with the computation of volumes in phase spaces of high dimension. The present work provides a starting point for overcoming this hurdle with some new ideas and implements them numerically. Specifically, an algorithm that uses tube dynamics to provide the initial bounding box for a Monte Carlo volume determination is used. The combination of a fine scale method for determining the phase space structure (invariant manifold theory) with statistical methods for volume computations (Monte Carlo) is the main contribution of this paper. The methodology is applied here to a three degree of freedom model problem and may be useful for higher degree of freedom systems as well.

Field Phenotyping Strategies and Breeding for Adaptation of Rice to Drought†

PubMed Central

Fischer, Ken S.; Fukai, Shu; Kumar, Arvind; Leung, Hei; Jongdee, Boonrat

2012-01-01

This paper is a section of the book “Drought phenotyping in crops: from theory to practice” (Monneveux Philippe and Ribaut Jean-Marcel eds, published by CGIAR Generation Challenge Programme. Texcoco, Mexico). The section describes recent experience in drought phenotyping in rice which is one of the most drought-susceptible crops. The section contains genetic and genomic resources for drought adaptation and methods for selection of drought-resistant varieties in rice. In appendix, there is experience from Thailand on integration of direct selection for grain yield and physiological traits to confer drought resistance. PMID:22934036

Gravitational radiation theory. M.A. Thesis - Rice Univ.; [survey of current research

NASA Technical Reports Server (NTRS)

Wilson, T. L.

1973-01-01

A survey is presented of current research in the theory of gravitational radiation. The mathematical structure of gravitational radiation is stressed. Furthermore, the radiation problem is treated independently from other problems in gravitation. The development proceeds candidly through three points of view - scalar, rector, and tensor radiation theory - and the corresponding results are stated.

Analyses to help identify individuals from a historical mass grave in Kassel, Germany.

PubMed

v Grumbkow, Philipp; Zipp, Anna; Grosskopf, Birgit; Fueldner, Kai; Hummel, Susanne

2012-01-01

In 2008, the skeletal remains of more than 60 human individuals were found in a mass grave on the grounds of the University of Kassel, Germany. There was no evidence helping to identify them or throwing light on the cause of their death. Mainly due to 14C age determination and initial hints on age and sex distribution, historians hypothesized that they had been soldiers of Napoleon's army who died in an epidemic in the winter of 1813/14. To test this assumption, morphological and molecular analyses were carried out on a sample. The morphological analyses comprised an age and sex determination as well as a macro- and micro-morphological inspection for pathological deviations after the commingled bones had been assembled as individuals. The molecular investigations aimed to identify the geographic origin of the remains. For this, mitochondrial and Y-chromosomal haplotypings were carried out. The results point to a group of mainly young men, some of them suffering from systemic inflammation of the periosteum. Others revealed severe aberrations in bone microstructure. The greatest similarities revealed by Y-haplogroup and -haplotype distribution were to populations that live in what are now the Benelux countries. All aspects support the thesis that these were soldiers of the Napoleonic army.

Chain conformations dictate multiscale charge transport phenomena in disordered semiconducting polymers

PubMed Central

Noriega, Rodrigo; Salleo, Alberto; Spakowitz, Andrew J.

2013-01-01

Existing models for the electronic properties of conjugated polymers do not capture the spatial arrangement of the disordered macromolecular chains over which charge transport occurs. Here, we present an analytical and computational description in which the morphology of individual polymer chains is dictated by well-known statistical models and the electronic coupling between units is determined using Marcus theory. The multiscale transport of charges in these materials (high mobility at short length scales, low mobility at long length scales) is naturally described with our framework. Additionally, the dependence of mobility with electric field and temperature is explained in terms of conformational variability and spatial correlation. Our model offers a predictive approach to connecting processing conditions with transport behavior. PMID:24062459

Investigation of giant magnetoconductance in organic devices based on hopping mechanism

NASA Astrophysics Data System (ADS)

Yang, F. J.; Qin, W.; Xie, S. J.

2014-04-01

We suggest a spin-dependent hopping mechanism which includes the effect of the external magnetic field as well as hyperfine interaction (HFI) to explain the observed giant magnetoconductance (MC) in non-magnetic organic devices. Based on the extended Marcus theory, we calculate the MC by using the master equation. It is found that a MC value as large as 91% is obtained under a low driving voltage. For suitable parameters, the theoretical results are in good agreement with the experimental data. Influences of the carrier density, HFI, and the carrier localization on the MC value are investigated. Especially, it is found that a low-dimensional structure of the organic materials is favorable to get a large MC value.

Investigation of giant magnetoconductance in organic devices based on hopping mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, F. J.; Qin, W.; Xie, S. J., E-mail: xsj@sdu.edu.cn

2014-04-14

We suggest a spin-dependent hopping mechanism which includes the effect of the external magnetic field as well as hyperfine interaction (HFI) to explain the observed giant magnetoconductance (MC) in non-magnetic organic devices. Based on the extended Marcus theory, we calculate the MC by using the master equation. It is found that a MC value as large as 91% is obtained under a low driving voltage. For suitable parameters, the theoretical results are in good agreement with the experimental data. Influences of the carrier density, HFI, and the carrier localization on the MC value are investigated. Especially, it is found thatmore » a low-dimensional structure of the organic materials is favorable to get a large MC value.« less

Chain conformations dictate multiscale charge transport phenomena in disordered semiconducting polymers.

PubMed

Noriega, Rodrigo; Salleo, Alberto; Spakowitz, Andrew J

2013-10-08

Existing models for the electronic properties of conjugated polymers do not capture the spatial arrangement of the disordered macromolecular chains over which charge transport occurs. Here, we present an analytical and computational description in which the morphology of individual polymer chains is dictated by well-known statistical models and the electronic coupling between units is determined using Marcus theory. The multiscale transport of charges in these materials (high mobility at short length scales, low mobility at long length scales) is naturally described with our framework. Additionally, the dependence of mobility with electric field and temperature is explained in terms of conformational variability and spatial correlation. Our model offers a predictive approach to connecting processing conditions with transport behavior.

NBO analysis and vibrational frequencies of tautomers of citrinin by density functional theory

USDA-ARS?s Scientific Manuscript database

Citrinin is a toxic polyketide contaminant of a number of agricultural commodities, notably Monascus-fermented red rice. Detailed structures and electronic properties of three tautomeric forms of citrinin were investigated using density functional theory calculations at various extended basis sets ...

A new probability distribution model of turbulent irradiance based on Born perturbation theory

NASA Astrophysics Data System (ADS)

Wang, Hongxing; Liu, Min; Hu, Hao; Wang, Qian; Liu, Xiguo

2010-10-01

The subject of the PDF (Probability Density Function) of the irradiance fluctuations in a turbulent atmosphere is still unsettled. Theory reliably describes the behavior in the weak turbulence regime, but theoretical description in the strong and whole turbulence regimes are still controversial. Based on Born perturbation theory, the physical manifestations and correlations of three typical PDF models (Rice-Nakagami, exponential-Bessel and negative-exponential distribution) were theoretically analyzed. It is shown that these models can be derived by separately making circular-Gaussian, strong-turbulence and strong-turbulence-circular-Gaussian approximations in Born perturbation theory, which denies the viewpoint that the Rice-Nakagami model is only applicable in the extremely weak turbulence regime and provides theoretical arguments for choosing rational models in practical applications. In addition, a common shortcoming of the three models is that they are all approximations. A new model, called the Maclaurin-spread distribution, is proposed without any approximation except for assuming the correlation coefficient to be zero. So, it is considered that the new model can exactly reflect the Born perturbation theory. Simulated results prove the accuracy of this new model.

Different electronic and charge-transport properties of four organic semiconductors Tetraazaperopyrenes derivatives

NASA Astrophysics Data System (ADS)

Shi, Yarui; Wei, Huiling; Liu, Yufang

2015-03-01

Tetraazaperopyrenes (TAPPs) derivatives are high-performance n-type organic semiconductor material families with the remarkable long-term stabilities. The charge carrier mobilities in TAPPs derivatives crystals were calculated by the density functional theory (DFT) method combined with the Marcus-Hush electron-transfer theory. The existence of considerable C-H…F-C bonding defines the conformation of the molecular structure and contributes to its stability. We illustrated how it is possible to control the electronic and charge-transport parameters of TAPPs derivatives as a function of the positions, a type of the substituents. It is found that the core substitution of TAPPs has a drastic influence on the charge-transport mobilities. The maximum electron mobility value of the core-brominated 2,9-bis (perfluoroalkyl)-substituted TAPPs is 0.521 cm2 V-1 s-1, which appear in the orientation angle 95° and 275°. The results demonstrate that the TAPPs with bromine substituents in ortho positions exhibit the best charge-transfer efficiency among the four different TAPP derivatives.

Control of a chemical reaction (photodegradation of the p3ht polymer) with nonlocal dielectric environments

PubMed Central

Peters, V. N.; Tumkur, T. U.; Zhu, G.; Noginov, M. A.

2015-01-01

Proximity to metallic surfaces, plasmonic structures, cavities and other inhomogeneous dielectric environments is known to control spontaneous emission, energy transfer, scattering, and many other phenomena of practical importance. The aim of the present study was to demonstrate that, in spirit of the Marcus theory, the rates of chemical reactions can, too, be influenced by nonlocal dielectric environments, such as metallic films and metal/dielectric bilayer or multilayer structures. We have experimentally shown that metallic, composite metal/dielectric substrates can, indeed, control ordering as well as photodegradation of thin poly-3-hexylthiophene (p3ht) films. In many particular experiments, p3ht films were separated from metal by a dielectric spacer, excluding conventional catalysis facilitated by metals and making modification of the nonlocal dielectric environment a plausible explanation for the observed phenomena. This first step toward understanding of a complex relationship between chemical reactions and nonlocal dielectric environments is to be followed by the theory development and a broader scope of thorough experimental studies. PMID:26434679

Risk forewarning model for rice grain Cd pollution based on Bayes theory.

PubMed

Wu, Bo; Guo, Shuhai; Zhang, Lingyan; Li, Fengmei

2018-03-15

Cadmium (Cd) pollution of rice grain caused by Cd-contaminated soils is a common problem in southwest and central south China. In this study, utilizing the advantages of the Bayes classification statistical method, we established a risk forewarning model for rice grain Cd pollution, and put forward two parameters (the prior probability factor and data variability factor). The sensitivity analysis of the model parameters illustrated that sample size and standard deviation influenced the accuracy and applicable range of the model. The accuracy of the model was improved by the self-renewal of the model through adding the posterior data into the priori data. Furthermore, this method can be used to predict the risk probability of rice grain Cd pollution under similar soil environment, tillage and rice varietal conditions. The Bayes approach thus represents a feasible method for risk forewarning of heavy metals pollution of agricultural products caused by contaminated soils. Copyright © 2017 Elsevier B.V. All rights reserved.

Unified interpretation of exciplex formation and marcus electron transfer on the basis of two-dimensional free energy surfaces.

PubMed

Murata, Shigeo; Tachiya, M

2007-09-27

The mechanism of exciplex formation proposed in a previous paper has been refined to show how exciplex formation and Marcus electron transfer (ET) in fluorescence quenching are related to each other. This was done by making simple calculations of the free energies of the initial (DA*) and final (D+A-) states of ET. First it was shown that the decrease in D-A distance can induce intermolecular ET even in nonpolar solvents where solvent orientational polarization is absent, and that it leads to exciplex formation. This is consistent with experimental results that exciplex is most often observed in nonpolar solvents. The calculation was then extended to ET in polar solvents where the free energies are functions of both D-A distance and solvent orientational polarization. This enabled us to discuss both exciplex formation and Marcus ET in the same D-A pair and solvent on the basis of 2-dimensional free energy surfaces. The surfaces contain more information about the rates of these reactions, the mechanism of fluorescence quenching by ET, etc., than simple reaction schemes. By changing the parameters such as the free energy change of reaction, solvent dielectric constants, etc., one can construct the free energy surfaces for various systems. The effects of free energy change of reaction and of solvent polarity on the mechanism and relative importance of exciplex formation and Marcus ET in fluorescence quenching can be well explained. The free energy surface will also be useful for discussion of other phenomena related to ET reactions.

Comparison of the Marcus and Pekar partitions in the context of non-equilibrium, polarizable-continuum solvation models

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, Zhi-Qiang; Herbert, John M., E-mail: herbert@chemistry.ohio-state.edu; Mewes, Jan-Michael

2015-11-28

The Marcus and Pekar partitions are common, alternative models to describe the non-equilibrium dielectric polarization response that accompanies instantaneous perturbation of a solute embedded in a dielectric continuum. Examples of such a perturbation include vertical electronic excitation and vertical ionization of a solution-phase molecule. Here, we provide a general derivation of the accompanying polarization response, for a quantum-mechanical solute described within the framework of a polarizable continuum model (PCM) of electrostatic solvation. Although the non-equilibrium free energy is formally equivalent within the two partitions, albeit partitioned differently into “fast” versus “slow” polarization contributions, discretization of the PCM integral equations failsmore » to preserve certain symmetries contained in these equations (except in the case of the conductor-like models or when the solute cavity is spherical), leading to alternative, non-equivalent matrix equations. Unlike the total equilibrium solvation energy, however, which can differ dramatically between different formulations, we demonstrate that the equivalence of the Marcus and Pekar partitions for the non-equilibrium solvation correction is preserved to high accuracy. Differences in vertical excitation and ionization energies are <0.2 eV (and often <0.01 eV), even for systems specifically selected to afford a large polarization response. Numerical results therefore support the interchangeability of the Marcus and Pekar partitions, but also caution against relying too much on the fast PCM charges for interpretive value, as these charges differ greatly between the two partitions, especially in polar solvents.« less

Neighbouring group processes in the deamination of protonated phenylalanine derivatives.

PubMed

Lioe, Hadi; O'Hair, Richard A J

2005-10-21

The gas-phase fragmentation of protonated phenylalanine and a series of its derivatives (tyrosine, 4-methylphenylalanine, 4-aminophenylalanine, 4-methoxyphenylalanine, 4-tert-butylphenylalanine, 4-fluorophenylalanine, 4-chlorophenylalanine, 4-bromophenylalanine, 4-iodophenylalanine, 4-cyanophenylalanine, 4-nitrophenylalanine, 3-fluorophenylalanine, and 3,4-dichlorophenylalanine) were examined using a combination of low energy CID in a quadrupole ion trap mass spectrometer as well as DFT calculations and RRKM modelling. In particular, the relationship between the electron-donating ability of the substituent and the competitive losses of H2O + CO and NH3 were explored through the application of the Hammett equation. It was found that electron-donating substituents promote the loss of NH3, while electron-withdrawing substituents suppress the loss of NH3 and favour the H2O + CO loss fragmentation channel instead. These observations are consistent with a neighbouring group pathway operating for the loss of NH3. Molecular orbital calculation (at the B3LYP/6-31+G(d,p) level of theory) were also performed for a range of derivatives to compare the relative transition state energy barriers for three competing mechanisms: (i) the combined loss of H2O + CO, which is triggered by an initial intramolecular proton transfer from the ammonium group to hydroxyl OH, followed by the combined loss of H2O and CO to form an immonium ion; (ii) loss of NH3 via an aryl assisted neighbouring group pathway to yield a phenonium ion; (iii) loss of NH3 via a 1,2-hydride migration process, which results in the formation of a benzyl cation. The relative energy barriers for H2O + CO loss remain nearly constant, while that for both NH3 pathways increase as the substituent moves from electron-donating to electron-withdrawing. The relative transition state energy for loss of NH3 via the aryl assisted neighbouring group pathway is always lower than that of the 1,2-hydride migration process. RRKM modelling of the DFT predicted barrier heights suggest that the rate constants for H2O + CO loss are insensitive to the substituent on the ring, while the NH3 loss channels are greatly affected by the substituent. These theoretical results are consistent with the experimental observation of the relative yields of the competing fragmentation channels. Finally, comparisons with published gas phase and condensed phase studies on related systems are made.

The gas-phase reaction between silylene and 2-butyne: kinetics, isotope studies, pressure dependence studies and quantum chemical calculations.

PubMed

Becerra, Rosa; Cannady, J Pat; Dormer, Guy; Walsh, Robin

2009-07-14

Time-resolved kinetic studies of the reactions of silylene, SiH(2), and dideutero-silylene, SiD(2), generated by laser flash photolysis of phenylsilane and phenylsilane-d(3), respectively, have been carried out to obtain rate coefficients for their bimolecular reactions with 2-butyne, CH(3)C[triple bond, length as m-dash]CCH(3). The reactions were studied in the gas phase over the pressure range 1-100 Torr in SF(6) bath gas at five temperatures in the range 294-612 K. The second-order rate coefficients, obtained by extrapolation to the high pressure limits at each temperature, fitted the Arrhenius equations where the error limits are single standard deviations: log(k(H)(Infinity)/cm(3) molecule(-1) s(-1) = (-9.67 +/- 0.04) + (1.71 +/- 0.33) kJ mol(1)/RTIn10log(k(D)(Infinity)/cm(3) molecule(-1) s(-1) = (-9.65 +/- 0.01) + (1.92 +/- 0.13) kJ mol(-1)/RTIn10. Additionally, pressure-dependent rate coefficients for the reaction of SiH(2) with 2-butyne in the presence of He (1-100 Torr) were obtained at 301, 429 and 613 K. Quantum chemical (ab initio) calculations of the SiC(4)H(8) reaction system at the G3 level support the formation of 2,3-dimethylsilirene [cyclo-SiH(2)C(CH(3))[double bond, length as m-dash]C(CH(3))-] as the sole end product. However, reversible formation of 2,3-dimethylvinylsilylene [CH(3)CH[double bond, length as m-dash]C(CH(3))SiH] is also an important process. The calculations also indicate the probable involvement of several other intermediates, and possible products. RRKM calculations are in reasonable agreement with the pressure dependences at an enthalpy value for 2,3-dimethylsilirene fairly close to that suggested by the ab initio calculations. The experimental isotope effects deviate significantly from those predicted by RRKM theory. The differences can be explained by an isotopic scrambling mechanism, involving H-D exchange between the hydrogens of the methyl groups and the D-atoms in the ring in 2,3-dimethylsilirene-1,1-d(2). A detailed mechanism involving several intermediate species, which is consistent with the G3 energy surface, is proposed to account for this.

SS Edgar M. Queeny collision with the Liberian S/T Corinthos, Marcus Hook, Pennsylvania, 31 January 1975. Marine casualty report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1977-10-27

At 0029, on January 31, 1975, the U.S. Registered tankship SS EDGAR M. QUEENY, laden with chemical and petroleum products, was maneuvering into Marcus Hook channel of the Delaware River in Pennsylvania, when it collided with the Liberian tanker S/T CORINTHOS which was moored and discharging a bulk cargo of crude oil at the British Petroleum Company dock. The port anchor of the QUEENY slightly penetrated the port side plating of the CORINTHOS at an angle of about 39 deg. into one or more of the wing cargo tanks, which were being pumped and were approximately half full. Almost immediately,more » a series of increasingly intense explosions began in the CORINTHOS, and the vessel was engulfed in flames. Twenty-six persons were killed or are missing and 11 were injured in this accident. The QUEENY suffered minor damage but the CORINTHOS was destroyed. The Delaware River was polluted by oil about Marcus Hook. Property damage was estimated to be $20 million.« less

Communication: Standard surface hopping predicts incorrect scaling for Marcus' golden-rule rate: The decoherence problem cannot be ignored

NASA Astrophysics Data System (ADS)

Landry, Brian R.; Subotnik, Joseph E.

2011-11-01

We evaluate the accuracy of Tully's surface hopping algorithm for the spin-boson model for the case of a small diabatic coupling parameter (V). We calculate the transition rates between diabatic surfaces, and we compare our results to the expected Marcus rates. We show that standard surface hopping yields an incorrect scaling with diabatic coupling (linear in V), which we demonstrate is due to an incorrect treatment of decoherence. By modifying standard surface hopping to include decoherence events, we recover the correct scaling (˜V2).

Insight into the kinetics and thermodynamics of the hydride transfer reactions between quinones and lumiflavin: a density functional theory study.

PubMed

Reinhardt, Clorice R; Jaglinski, Tanner C; Kastenschmidt, Ashly M; Song, Eun H; Gross, Adam K; Krause, Alyssa J; Gollmar, Jonathan M; Meise, Kristin J; Stenerson, Zachary S; Weibel, Tyler J; Dison, Andrew; Finnegan, Mackenzie R; Griesi, Daniel S; Heltne, Michael D; Hughes, Tom G; Hunt, Connor D; Jansen, Kayla A; Xiong, Adam H; Hati, Sanchita; Bhattacharyya, Sudeep

2016-09-01

The kinetics and equilibrium of the hydride transfer reaction between lumiflavin and a number of substituted quinones was studied using density functional theory. The impact of electron withdrawing/donating substituents on the redox potentials of quinones was studied. In addition, the role of these substituents on the kinetics of the hydride transfer reaction with lumiflavin was investigated in detail under the transition state (TS) theory assumption. The hydride transfer reactions were found to be more favorable for an electron-withdrawing substituent. The activation barrier exhibited a quadratic relationship with the driving force of these reactions as derived under the formalism of modified Marcus theory. The present study found a significant extent of electron delocalization in the TS that is stabilized by enhanced electrostatic, polarization, and exchange interactions. Analysis of geometry, bond-orders, and energetics revealed a predominant parallel (Leffler-Hammond) effect on the TS. Closer scrutiny reveals that electron-withdrawing substituents, although located on the acceptor ring, reduce the N-H bond order of the donor fragment in the precursor complex. Carried out in the gas-phase, this is the first ever report of a theoretical study of flavin's hydride transfer reactions with quinones, providing an unfiltered view of the electronic effect on the nuclear reorganization of donor-acceptor complexes.

Molecular interactions investigated with DFT calculations of QTAIM and NBO analyses: An application to dimeric structures of rice α-amylase/subtilisin inhibitor

NASA Astrophysics Data System (ADS)

Astani, Elahe K.; Hadipour, Nasser L.; Chen, Chun-Jung

2017-03-01

Characterization of the dimer interactions at the dimeric interface of the crystal structure of rice α-amylase/subtilisin inhibitor (RASI) were performed using the quantum theory of atoms in molecules (QTAIM) and natural bonding orbital (NBO) analyses at the density-functional theory (DFT) level. The results revealed that Gly27 and Arg151 of chain A are the main residues involved in hydrogen bonds, dipole-dipole, and charge-dipole interactions with Gly64, Ala66, Ala67 and Arg81 of chain B at the dimeric interface. Calcium ion of chain A plays the significant role in the stability of the dimeric structure through a strong charge-charge interaction with Ala66.

Gas-Phase Reaction Pathways and Rate Coefficients for the Dichlorosilane-Hydrogen and Trichlorosilane-Hydrogen Systems

NASA Technical Reports Server (NTRS)

Dateo, Christopher E.; Walch, Stephen P.

2002-01-01

As part of NASA Ames Research Center's Integrated Process Team on Device/Process Modeling and Nanotechnology our goal is to create/contribute to a gas-phase chemical database for use in modeling microelectronics devices. In particular, we use ab initio methods to determine chemical reaction pathways and to evaluate reaction rate coefficients. Our initial studies concern reactions involved in the dichlorosilane-hydrogen (SiCl2H2--H2) and trichlorosilane-hydrogen (SiCl2H-H2) systems. Reactant, saddle point (transition state), and product geometries and their vibrational harmonic frequencies are determined using the complete-active-space self-consistent-field (CASSCF) electronic structure method with the correlation consistent polarized valence double-zeta basis set (cc-pVDZ). Reaction pathways are constructed by following the imaginary frequency mode of the saddle point to both the reactant and product. Accurate energetics are determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations (CCSD(T)) extrapolated to the complete basis set limit. Using the data from the electronic structure calculations, reaction rate coefficients are obtained using conventional and variational transition state and RRKM theories.

Columnar mesophases of hexabenzocoronene derivatives. II. Charge carrier mobility

NASA Astrophysics Data System (ADS)

Kirkpatrick, James; Marcon, Valentina; Kremer, Kurt; Nelson, Jenny; Andrienko, Denis

2008-09-01

Combining atomistic molecular dynamic simulations, Marcus-Hush theory description of charge transport rates, and master equation description of charge dynamics, we correlate the temperature-driven change of the mesophase structure with the change of charge carrier mobilities in columnar phases of hexabenzocoronene derivatives. The time dependence of fluctuations in transfer integrals shows that static disorder is predominant in determining charge transport characteristics. Both site energies and transfer integrals are distributed because of disorder in the molecular arrangement. It is shown that the contributions to the site energies from polarization and electrostatic effects are of opposite sign for positive charges. We look at three mesophases of hexabenzocoronene: herringbone, discotic, and columnar disordered. All results are compared to time resolved microwave conductivity data and show excellent agreement with no fitting parameters.

Columnar mesophases of hexabenzocoronene derivatives. II. Charge carrier mobility.

PubMed

Kirkpatrick, James; Marcon, Valentina; Kremer, Kurt; Nelson, Jenny; Andrienko, Denis

2008-09-07

Combining atomistic molecular dynamic simulations, Marcus-Hush theory description of charge transport rates, and master equation description of charge dynamics, we correlate the temperature-driven change of the mesophase structure with the change of charge carrier mobilities in columnar phases of hexabenzocoronene derivatives. The time dependence of fluctuations in transfer integrals shows that static disorder is predominant in determining charge transport characteristics. Both site energies and transfer integrals are distributed because of disorder in the molecular arrangement. It is shown that the contributions to the site energies from polarization and electrostatic effects are of opposite sign for positive charges. We look at three mesophases of hexabenzocoronene: herringbone, discotic, and columnar disordered. All results are compared to time resolved microwave conductivity data and show excellent agreement with no fitting parameters.

The Kassel Laboratory Astrophysics Thz Spectrometrs

NASA Astrophysics Data System (ADS)

Chantzos, Johanna; Herberth, Doris; Kutzer, Pia; Muster, Christoph; Fuchs, Guido W.; Giesen, Thomas

2016-06-01

We present a brief overview of the recently established laboratory astrophysics group in Kassel/Germany with a focus on our THz technology. After an outline of our laboratory equipment and recent projects the talk will focus on our new fast spectral scan technique for molecular jet experiments. Here, a new test setup for broadband fast sweep spectrometry in the MW to submm wavelength region has been realized and can be applied to identify transient molecules in a supersonic jet. An arbitrary waveform generator (AWG) is used to generate chirped pulses with a linear frequency sweep in the MHz regime. Pulse durations are of a few microseconds. These pulses are up-converted in frequency, e.g. into the 50 GHz microwave frequency range utilizing a synthesizer, or using a synthesizer plus standard amplifier multiplier chain (AMC) to reach the 100-300 GHz region. As test, NH_3 has been measured between 18-26 GHz in a supersonic jet of 500 μ s duration. Acetonitrile (CH_3CN) was tested in the (90-110) GHz range. The spectrometer is capable of providing fast, broadband and low-noise measurements. Experiments with non-stabel molecular production conditions can greatly benefit from these advantages. The setup enables the study of Van-der-Waals-clusters, as well as carbon chain molecules and small metal-containing refractory molecules when combined with appropriate molecule sources.

"Abnormal" salt and solvent effects on anion/cation electron-transfer reactions: an interpretation based on Marcus-Hush treatment.

PubMed

Garcia-Fernandez, E; Prado-Gotor, R; Sanchez, F

2005-08-11

Salt and solvent effects on the kinetics of the reactions [Fe(CN)6]3- + [Ru(NH3)5pz](2+) right arrow over left arrow [Fe(CN)6]4- + [Ru(NH3)5pz]3+ (pz = pyrazine) have been studied through T-jump measurements. The forward and reverse reactions show different behaviors: "abnormal" salt and solvent effects in the first case and normal effects in the second one. These facts imply an asymmetric behavior of anion/cation reactions depending on the charge of the oxidant. The results can be rationalized by using the Marcus-Hush treatment for electron-transfer reactions.

Effect of viscosity on photoinduced electron transfer reaction: An observation of the Marcus inverted region in homogeneous solvents

NASA Astrophysics Data System (ADS)

Saini, Rajesh Kumar; Kuchlyan, Jagannath; Sarkar, Nilmoni

2016-09-01

The viscosity effect of homogeneous solvents on the dynamics of photoinduced electron transfer (PET) reaction among the coumarins and N,N-dimethylaniline (DMA) is investigated using steady-state and time-resolved fluorescence spectroscopy. A bell shape Marcus inversion in the ET rates has been detected in the plot of ET rate constant (kq) with free energy change (ΔG0) in viscous solvents decanol and EG, but it is not observed in DMSO like low viscous solvent. We have also reported that there is no complex formation between the coumarin dye and DMA molecule by using fluorescence correlation spectroscopy.

Thermodynamic and spectroscopic speciation to explain the blackening process of hematite formed by atmospheric SO2 impact: the case of Marcus Lucretius House (Pompeii).

PubMed

Maguregui, Maite; Knuutinen, Ulla; Martínez-Arkarazo, Irantzu; Castro, Kepa; Madariaga, Juan M

2011-05-01

After many decades exposed to a polluted environment, in some areas of Marcus Lucretius House, there are clear signs that plasters and hematite pigments are suffering deterioration. In the exhaustive analysis of the black layer covering the red pigment hematite it was possible to identify magnetite (Fe(3)O(4)) as responsible for the black colour, which always appears in combination with gypsum. Thermodynamic modelling stated that the presence of gypsum as well as the transformation of hematite into magnetite is a consequence of the attack of atmospheric SO(2).

"East side story": on being an epidemiologist in the former USSR: an interview with Marcus Klingberg.

PubMed

Klingberg, Marcus

2006-01-01

Marcus Klingberg was born on 7 October 1918, in Warsaw, Poland, into a Hasidic, rabbinical family. After the Nazi invasion of Poland, he escaped to the USSR where he trained and worked as an epidemiologist from 1939 to 1945. For 35 years after the war, he continued his professional work in Israel. The harsh conditions within the Soviet Union during World War II provided a challenging setting for epidemiologic work-a setting that has remained largely hidden from Western view. In this interview, Klingberg describes his work as an epidemiologist in the USSR and his subsequent encounter with Western epidemiology.

Delaware River water quality Bristol to Marcus Hook, Pennsylvania, August 1949 to December 1963

USGS Publications Warehouse

Keighton, Walter B.

1965-01-01

During the 14-year period from August 1949 to July 1963, the U.S. Geological Survey, in cooperation with the city of Philadelphia, collected samples of river water once each month in the 43-mile reach of the Delaware River from Bristol to Marcus Hook, Pa., and daily at Trenton, 10 miles upstream from Bristol. This part of the Delaware is an estuary into which salt water is brought by tides; fresh water flows into the estuary at Trenton, NJ, and farther downstream from the Schuylkill River and other tributaries of the Delaware. In March, April, and May, when fresh-water flow is high, the average concentration of dissolved solids in the water at Bristol was 76 ppm (parts per million), and at Marcus Hook 112 PPM In August and September, streamflow is lower, and the average concentration of dissolved solids increased to 117 PPM at Bristol and 804 PPM at Marcus Hook. Major salinity invasions of the Delaware River occurred in 1949, 1953, 1954, 1957, and 1963. In each of these years the fresh-water flow into the tidal river at Trenton was low during the period from July to October. The greatest dissolved-solids concentrations in these monthly samples were 160 PPM at Bristol and 4,000 PPM at Marcus Hook. At times the dissolved-oxygen concentration of the river water has become dangerously low, especially in that reach of the river between Wharton Street and League Island. At the Benjamin Franklin Bridge, one-third of the samples of river water were less than 30 percent saturated with oxygen; however, no trend, either for better or for worse, was apparent during the 14-year period. It is useful now to summarize these monthly analyses for the period 1949-63 even though a much more detailed description of water quality in this reach of the estuary will soon become available through the use of recording instrumental conditions. This compendium of water-quality data is useful as an explicit statement of water quality during the 14-year study period and is valuable for directing attention to water-quality problems for selecting instrument sites, and for making comparative studies with the more detailed information which is already being obtained with the aid of recording instruments.

Mott physics beyond the Brinkman-Rice scenario

NASA Astrophysics Data System (ADS)

Wysokiński, Marcin M.; Fabrizio, Michele

2017-04-01

The main flaw of the well-known Brinkman-Rice description, obtained through the Gutzwiller approximation, of the paramagnetic Mott transition in the Hubbard model is in neglecting high-energy virtual processes that generate, for instance, the antiferromagnetic exchange J ˜t2/U . Here, we propose a way to capture those processes by combining the Brinkman-Rice approach with a variational Schrieffer-Wolff transformation, and apply this method to study the single-band metal-to-insulator transition in a Bethe lattice with infinite coordination number, where the Gutzwiller approximation becomes exact. We indeed find for the Mott transition a description very close to the real one provided by the dynamical mean-field theory, an encouraging result in view of possible applications to more involved models.

An improved exceedance theory for combined random stresses

NASA Technical Reports Server (NTRS)

Lester, H. C.

1974-01-01

An extension is presented of Rice's classic solution for the exceedances of a constant level by a single random process to its counterpart for an n-dimensional vector process. An interaction boundary, analogous to the constant level considered by Rice for the one-dimensional case, is assumed in the form of a hypersurface. The theory for the numbers of boundary exceedances is developed by using a joint statistical approach which fully accounts for all cross-correlation effects. An exact expression is derived for the n-dimensional exceedance density function, which is valid for an arbitrary interaction boundary. For application to biaxial states of combined random stress, the general theory is reduced to the two-dimensional case. An elliptical stress interaction boundary is assumed and the exact expression for the density function is presented. The equations are expressed in a format which facilitates calculating the exceedances by numerically evaluating a line integral. The behavior of the density function for the two-dimensional case is briefly discussed.

Theory of chemical kinetics and charge transfer based on nonequilibrium thermodynamics.

PubMed

Bazant, Martin Z

2013-05-21

Advances in the fields of catalysis and electrochemical energy conversion often involve nanoparticles, which can have kinetics surprisingly different from the bulk material. Classical theories of chemical kinetics assume independent reactions in dilute solutions, whose rates are determined by mean concentrations. In condensed matter, strong interactions alter chemical activities and create variations that can dramatically affect the reaction rate. The extreme case is that of a reaction coupled to a phase transformation, whose kinetics must depend not only on the order parameter but also on its gradients at phase boundaries. Reaction-driven phase transformations are common in electrochemistry, when charge transfer is accompanied by ion intercalation or deposition in a solid phase. Examples abound in Li-ion, metal-air, and lead-acid batteries, as well as metal electrodeposition-dissolution. Despite complex thermodynamics, however, the standard kinetic model is the Butler-Volmer equation, based on a dilute solution approximation. The Marcus theory of charge transfer likewise considers isolated reactants and neglects elastic stress, configurational entropy, and other nonidealities in condensed phases. The limitations of existing theories recently became apparent for the Li-ion battery material LixFePO4 (LFP). It has a strong tendency to separate into Li-rich and Li-poor solid phases, which scientists believe limits its performance. Chemists first modeled phase separation in LFP as an isotropic "shrinking core" within each particle, but experiments later revealed striped phase boundaries on the active crystal facet. This raised the question: What is the reaction rate at a surface undergoing a phase transformation? Meanwhile, dramatic rate enhancement was attained with LFP nanoparticles, and classical battery models could not predict the roles of phase separation and surface modification. In this Account, I present a general theory of chemical kinetics, developed over the past 7 years, which is capable of answering these questions. The reaction rate is a nonlinear function of the thermodynamic driving force, the free energy of reaction, expressed in terms of variational chemical potentials. The theory unifies and extends the Cahn-Hilliard and Allen-Cahn equations through a master equation for nonequilibrium chemical thermodynamics. For electrochemistry, I have also generalized both Marcus and Butler-Volmer kinetics for concentrated solutions and ionic solids. This new theory provides a quantitative description of LFP phase behavior. Concentration gradients and elastic coherency strain enhance the intercalation rate. At low currents, the charge-transfer rate is focused on exposed phase boundaries, which propagate as "intercalation waves", nucleated by surface wetting. Unexpectedly, homogeneous reactions are favored above a critical current and below a critical size, which helps to explain the rate capability of LFP nanoparticles. Contrary to other mechanisms, elevated temperatures and currents may enhance battery performance and lifetime by suppressing phase separation. The theory has also been extended to porous electrodes and could be used for battery engineering with multiphase active materials. More broadly, the theory describes nonequilibrium chemical systems at mesoscopic length and time scales, beyond the reach of molecular simulations and bulk continuum models. The reaction rate is consistently defined for inhomogeneous, nonequilibrium states, for example, with phase separation, large electric fields, or mechanical stresses. This research is also potentially applicable to fluid extraction from nanoporous solids, pattern formation in electrophoretic deposition, and electrochemical dynamics in biological cells.

Regulation Of The Tumor Suppressor Activity Of p53 In Human Breast Cancer

DTIC Science & Technology

1998-09-01

Cell. Biol. 11, (51). As with the studies reported here (Fig. 2 and Table I), the 34. Diller, L., Kassel, J., Nelson, C. E., Gryka , M . A., Litwak, G...this research: 1. Resnick-Silverman, L., S. St Clair, M . Maurer, K. Zhao, and J. J. Manfredi. 1998. Identification of a novel class of genomic DNA...Zhao, J. F. Pizzolato, M . Fonarev, J. C. Langer, and J. J. Manfredi. 1998. Constitutive expression of the cyclin-dependent kinase inhibitor p21 is

Photodissociation pathways and lifetimes of protonated peptides and their dimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aravind, G.; Klaerke, B.; Rajput, J.

2012-01-07

Photodissociation lifetimes and fragment channels of gas-phase, protonated YA{sub n} (n = 1,2) peptides and their dimers were measured with 266 nm photons. The protonated monomers were found to have a fast dissociation channel with an exponential lifetime of {approx}200 ns while the protonated dimers show an additional slow dissociation component with a lifetime of {approx}2 {mu}s. Laser power dependence measurements enabled us to ascribe the fast channel in the monomer and the slow channel in the dimer to a one-photon process, whereas the fast dimer channel is from a two-photon process. The slow (1 photon) dissociation channel in themore » dimer was found to result in cleavage of the H-bonds after energy transfer through these H-bonds. In general, the dissociation of these protonated peptides is non-prompt and the decay time was found to increase with the size of the peptides. Quantum RRKM calculations of the microcanonical rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis of the equipartition theorem. It demonstrates encouraging results in predicting fragmentation lifetimes of protonated peptides. Finally, we present the first experimental evidence for a photo-induced conversion of tyrosine-containing peptides into monocyclic aromatic hydrocarbon along with a formamide molecule both found in space.« less

Molecular aspects of the Eu3+/Eu2+ redox reaction at the interface between a molten salt and a metallic electrode

NASA Astrophysics Data System (ADS)

Pounds, Michael A.; Salanne, Mathieu; Madden, Paul A.

2015-09-01

We perform molecular dynamics simulations of a system consisting of Eu3+ and Eu2+ species dissolved in a high-temperature KCl electrolyte between two metallic electrodes. The interaction potential includes ion polarisation effects, and a constant electric potential is maintained within the electrodes by allowing the atomic charges to fluctuate in response to the environment. This setup allows us to study the electrochemical Eu3+/Eu2+ reaction in the framework of Marcus theory. Numerous studies have pointed to the highly structured nature of ionic liquids and molten salts close to solid surfaces which is not accounted for in the conventional mean-field description of this interface that underpins the theories of electrochemical reaction rates. Here we examine the influence on the kinetics of the charge-transfer event of the electrical potential across the electrode-electrolyte interface and on the effect of the presence of charged surface on the coordination structure and energetics of the ions in the region important for the charge-transfer event.

Theoretical study of anisotropic mobility in ladder-type molecule organic semiconductors

NASA Astrophysics Data System (ADS)

Wei, Hui-Ling; Liu, Yu-Fang

2014-09-01

The properties of two ladder-type semiconductors {M1: 2,2'-(2,7-dihexy1-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-4,9-diylidene) dimalononitrile and M2: 2,7-dihexy1-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-4,9-dione} as the n-type and ambipolar organic materials are systematically investigated using the first-principle density functional theory combined with the Marcus-Hush electron transfer theory. It is found that the substitution of M1 induces large changes in its electron-transfer mobility of 1.370 cm2 V-1 s-1. M2 has both large electron- and hole-transfer mobility of 0.420 and 0.288 cm2 V-1 s-1, respectively, which indicates that M2 is potentially a high efficient ambipolar organic semiconducting material. Both the M1 and M2 crystals show remarkable anisotropic behavior. A proper design of the n-type and ambipolar organic electronic materials, which may have high mobility performance, is suggested based on the investigated two molecules.

Between Marxism and psychoanalysis: antifascism and antihomosexuality in the Frankfurt School.

PubMed

Halle, R

1995-01-01

In their efforts to utilize individualist psychoanalysis as a tool for understanding mass behavior, the social theorists associated with the Frankfurt School increasingly came to rely on a static, essentializing construction of sexuality which ultimately led to an equation of fascism and homosexuality. Heretofore unexamined in studies of the Frankfurt School, this equation will here serve as the starting point for a fundamental critique of the concept of sexuality developed by this influential circle of Marxist thinkers. While directed at the concept of sexuality, such a critique more importantly opens up the underlying understanding of the social and psychological realms advanced by Critical Theory. Attending to the equation of homosexuality and fascism as the central point of concern, this essay will first trace the introduction of psychoanalysis into Critical Theory through Erich Fromm and then investigate the extent of Fromm's influence on the concept of sexuality propounded by his colleagues, especially Max Horkheimer and Theodor W. Adorno. Finally, it will take up a frequently overlooked essay by Herbert Marcuse which promoted a vision of sexuality radically different from that of his associates.

Self-exchange reaction of [Ni(mnt)2](1-,2-) in nonaqueous solutions.

PubMed

Kowert, Bruce A; Fehr, Michael J; Sheaff, Pamela J

2008-07-07

The rate constant, k, for the homogeneous electron transfer (self-exchange) reaction between the diamagnetic bis(maleonitriledithiolato)nickel dianion, [Ni(mnt) 2] (2-), and the paramagnetic monoanion, [Ni(mnt) 2] (1-), has been determined in acetone and nitromethane (CH 3NO 2) using (13)C NMR line widths at 22 degrees C (mnt = 1,2-S 2C 2(CN) 2). The values of k (2.91 x 10 (6) M (-1) s (-1) in acetone, 5.78 x 10 (6) M (-1) s (-1) in CH 3NO 2) are faster than those for the electron transfer reactions of other Ni(III,II) couples; the structures of [Ni(mnt) 2] (1-) and [Ni(mnt) 2] (2-) allow for a favorable overlap that lowers the free energy of activation. The values of k are consistent with the predictions of Marcus theory. In addition to k, the spin-lattice relaxation time, T 1e, of [Ni(mnt) 2] (1-) is obtained from the NMR line width analysis; the values are consistent with those predicted by spin relaxation theory.

Quenching mechanism of Zn(salicylaldimine) by nitroaromatics.

PubMed

Germain, Meaghan E; Vargo, Thomas R; McClure, Beth Anne; Rack, Jeffrey J; Van Patten, P Gregory; Odoi, Michael; Knapp, Michael J

2008-07-21

Nitroaromatics and nitroalkanes quench the fluorescence of Zn(Salophen) (H2Salophen = N,N'-phenylene-bis-(3,5-di- tert-butylsalicylideneimine); ZnL(R)) complexes. A structurally related family of ZnL(R) complexes (R = OMe, di-tBu, tBu, Cl, NO2) were prepared, and the mechanisms of fluorescence quenching by nitroaromatics were studied by a combined kinetics and spectroscopic approach. The fluorescent quantum yields for ZnL(R) were generally high (Phi approximately 0.3) with sub-nanosecond fluorescence lifetimes. The fluorescence of ZnL(R) was quenched by nitroaromatic compounds by a mixture of static and dynamic pathways, reflecting the ZnL(R) ligand bulk and reduction potential. Steady-state Stern-Volmer plots were curved for ZnL(R) with less-bulky substituents (R = OMe, NO2), suggesting that both static and dynamic pathways were important for quenching. Transient Stern-Volmer data indicated that the dynamic pathway dominated quenching for ZnL(R) with bulky substituents (R = tBu, DtBu). The quenching rate constants with varied nitroaromatics (ArNO2) followed the driving force dependence predicted for bimolecular electron transfer: ZnL* + ArNO2 --> ZnL(+) + ArNO2(-). A treatment of the diffusion-corrected quenching rates with Marcus theory yielded a modest reorganization energy (lambda = 25 kcal/mol), and a small self-exchange reorganization energy for ZnL*/ZnL(+) (ca. 20 kcal/mol) was estimated from the Marcus cross-relation, suggesting that metal phenoxyls may be robust biological redox cofactors. Electronic structure calculations indicated very small changes in bond distances for the ZnL --> ZnL(+) oxidation, suggesting that solvation was the dominant contributor to the observed reorganization energy. These mechanistic insights provide information that will be helpful to further develop ZnL(R) as sensors, as well as for potential photoinduced charge transfer chemistry.

Excited-state redox properties of ruthenium(II) phthalocyanine from electron-transfer quenching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasad, D.R.; Ferraudi, G.

1982-09-30

Electron-transfer reactions between the lowest-lying triplet state, /sup 3/..pi pi../sup */, of ruthenium (phthalocyanine)(pyridine)/sub 2/ and various nitroaromatic compounds have been studied by laser and conventional flash photolysis. Quenching rate constants determined for the oxidation of the excited state have been treated according to the Marcus-Hush theory. A self-exchange rate constant K approx. 10/sup 7/ M/sup -1/ x/sup -1/ was determined for the self-exchange reaction between the /sup 3/..pi pi../sup */ and radical cation, Ru(ph)(py)/sub 2//sup +/. Such a value indicates that the major component to the Franck-Condon reorganizational energy is the outer-sphere contribution. The photochemical properties of the phthalocyaninesmore » are discussed in terms of the redox potentials estimate for various excited states.« less

Crystal structure and charge transport properties of poly(arylene-ethynylene) derivatives: A DFT approach

NASA Astrophysics Data System (ADS)

Garzón, Andrés; Granadino-Roldán, José M.; García, Gregorio; Moral, Mónica; Fernández-Gómez, Manuel

2013-04-01

In the present study, a series of crystalline poly(arylene-ethynylene) copolymers containing phenylethynylene and 2,5-dialkoxy-phenylethynylene units together with 1,3,4-thiadiazole rings has been modeled by means of periodic calculations. Optimized three-dimensional polymeric structures show interchain distances that are consistent with the experimental values reported for a related polymer. It has also been observed that the presence of pendant alkoxy chains brings on both a further flattening and a separation of the coplanar chains. This fact is linked to a decrease of the interchain cofacial distance. The electron transport character of the polymer crystal structures was assessed through Marcus theory. Electronic coupling between neighboring polymer chains is most influenced by the presence of alkoxy chains giving rise to an expectable enhancement of the electron hopping mobility.

Elementary reaction profile and chemical kinetics study of [C(1D)/(3P) + SiH4] with the CCSD(T) method

NASA Astrophysics Data System (ADS)

Ranka, Karnamohit; Perera, Ajith; Bartlett, Rodney J.

2017-07-01

Carbon and silicon-based molecules are omnipresent in the fields of combustion, atmospheric, semiconductor, and astronomical chemistry, among others. This paper reports the underlying elementary reactions for the [C(1D) + SiH4] and [C(3P) + SiH4] reaction profiles, optimized geometries of the intermediates, transition states (at the CCSD(T) level), RRKM and TST rate constants, and the corresponding branching ratios. Previously unreported van der Waals complex intermediates have been found for both reactions.

Describing long-range charge-separation processes with subsystem density-functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solovyeva, Alisa; Neugebauer, Johannes, E-mail: j.neugebauer@uni-muenster.de; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu

2014-04-28

Long-range charge-transfer processes in extended systems are difficult to describe with quantum chemical methods. In particular, cost-effective (non-hybrid) approximations within time-dependent density functional theory (DFT) are not applicable unless special precautions are taken. Here, we show that the efficient subsystem DFT can be employed as a constrained DFT variant to describe the energetics of long-range charge-separation processes. A formal analysis of the energy components in subsystem DFT for such excitation energies is presented, which demonstrates that both the distance dependence and the long-range limit are correctly described. In addition, electronic couplings for these processes as needed for rate constants inmore » Marcus theory can be obtained from this method. It is shown that the electronic structure of charge-separated states constructed by a positively charged subsystem interacting with a negatively charged one is difficult to converge — charge leaking from the negative subsystem to the positive one can occur. This problem is related to the delocalization error in DFT and can be overcome with asymptotically correct exchange–correlation (XC) potentials or XC potentials including a sufficiently large amount of exact exchange. We also outline an approximate way to obtain charge-transfer couplings between locally excited and charge-separated states.« less

Chemical characteristics of Delaware River water, Trenton, New Jersey, to Marcus Hook, Pennsylvania

USGS Publications Warehouse

Durfor, Charles N.; Keighton, Walter B.

1954-01-01

This progress report gives the results of an investigation of the quality of water in the Delaware River from Trenton, N. J. to Marcus Hook, Pa., for the period August 1949 to December 1952. The Delaware River is the principal source of water for the many industries and municipal water supplies along this reach of the river and both industries and municipalities use it for the disposal of their wastes. Consequently, a study of the quality of the water and variations in the quality caused by changes in streamflow, tidal effects, pollution and other factors is important to the many users. In both New Jersey and Pennsylvania steps are being taken to abate pollution, thus it is of more than passing interest to measure the effects of waste treatment on the quality of the Delaware River water. At average or higher rates of streamflow the mineral content of the water increases slightly from Trenton to Marcus Hook. There is little variation in the concentration of dissolved minerals from bank to bank or from top to bottom of the river. At times of protracted low rates of flow the effect of ocean water mixing with the river water may be noted as far upstream as Philadelphia. At such times the salinity is often greater near the bottom of the river than near the top. The increase in chloride concentration upstream from Philadelphia is small compared to the rapid increase downstream from Philadelphia. Temperatures of offshore water vary with the season, but on a given day are substantially uniform throughout the reach of the river from Trenton to Marcus Hook. The water contains less dissolved oxygen as it flows downstream indicating that oxygen is being consumed by oxidizable matter. From Philadelphia downstream there are periods, especially in late summer, when the dissolved oxygen is barely sufficient to meet the oxygen demands of the pollution load.

Comparison of the GHSSmooth and the Rayleigh-Rice surface scatter theories

NASA Astrophysics Data System (ADS)

Harvey, James E.; Pfisterer, Richard N.

2016-09-01

The scalar-based GHSSmooth surface scatter theory results in an expression for the BRDF in terms of the surface PSD that is very similar to that provided by the rigorous Rayleigh-Rice (RR) vector perturbation theory. However it contains correction factors for two extreme situations not shared by the RR theory: (i) large incident or scattered angles that result in some portion of the scattered radiance distribution falling outside of the unit circle in direction cosine space, and (ii) the situation where the relevant rms surface roughness, σrel, is less than the total intrinsic rms roughness of the scattering surface. Also, the RR obliquity factor has been discovered to be an approximation of the more general GHSSmooth obliquity factor due to a little-known (or long-forgotten) implicit assumption in the RR theory that the surface autocovariance length is longer than the wavelength of the scattered radiation. This assumption allowed retaining only quadratic terms and lower in the series expansion for the cosine function, and results in reducing the validity of RR predictions for scattering angles greater than 60°. This inaccurate obliquity factor in the RR theory is also the cause of a complementary unrealistic "hook" at the high spatial frequency end of the predicted surface PSD when performing the inverse scattering problem. Furthermore, if we empirically substitute the polarization reflectance, Q, from the RR expression for the scalar reflectance, R, in the GHSSmooth expression, it inherits all of the polarization capabilities of the rigorous RR vector perturbation theory.

Kinetics of the benzyl + O(3P) reaction: a quantum chemical/statistical reaction rate theory study.

PubMed

da Silva, Gabriel; Bozzelli, Joseph W

2012-12-14

The resonance stabilized benzyl radical is an important intermediate in the combustion of aromatic hydrocarbons and in polycyclic aromatic hydrocarbon (PAH) formation in flames. Despite being a free radical, benzyl is relatively stable in thermal, oxidizing environments, and is predominantly removed through bimolecular reactions with open-shell species other than O(2). In this study the reaction of benzyl with ground-state atomic oxygen, O((3)P), is examined using quantum chemistry and statistical reaction rate theory. C(7)H(7)O energy surfaces are generated at the G3SX level, and include several novel pathways. Transition state theory is used to describe elementary reaction kinetics, with canonical variational transition state theory applied for barrierless O atom association with benzyl. Apparent rate constants and branching ratios to different product sets are obtained as a function of temperature and pressure from solving the time-dependent master equation, with RRKM theory for microcanonical k(E). These simulations indicate that the benzyl + O reaction predominantly forms the phenyl radical (C(6)H(5)) plus formaldehyde (HCHO), with lesser quantities of the C(7)H(6)O products benzaldehyde, ortho-quinone methide, and para-quinone methide (+H), along with minor amounts of the formyl radical (HCO) + benzene. Addition of O((3)P) to the methylene site in benzyl produces a highly vibrationally excited C(7)H(7)O* adduct, the benzoxyl radical, which can β-scission to benzaldehyde + H and phenyl + HCHO. In order to account for the experimental observation of benzene as the major reaction product, a roaming radical mechanism is proposed that converts the nascent products phenyl and HCHO to benzene + HCO. Oxygen atom addition at the ortho and para ring sites in benzyl, which has not been previously considered, is shown to lead to the quinone methides + H; these species are less-stable isomers of benzaldehyde that are proposed as important combustion intermediates, but are yet to be identified experimentally. Franck-Condon simulations of the benzaldehyde, o-quinone methide, and p-quinone methide photoelectron spectra suggest that these C(7)H(6)O isomers could be distinguished using tunable VUV photoionization mass spectrometry.

Dynamics of a Chlorophyll Dimer in Collective and Local Thermal Environments

DOE PAGES

Merkli, M.; Berman, Gennady Petrovich; Sayre, Richard Thomas; ...

2016-01-30

Here we present a theoretical analysis of exciton transfer and decoherence effects in a photosynthetic dimer interacting with collective (correlated) and local (uncorrelated) protein-solvent environments. Our approach is based on the framework of the spin-boson model. We derive explicitly the thermal relaxation and decoherence rates of the exciton transfer process, valid for arbitrary temperatures and for arbitrary (in particular, large) interaction constants between the dimer and the environments. We establish a generalization of the Marcus formula, giving reaction rates for dimer levels possibly individually and asymmetrically coupled to environments. We identify rigorously parameter regimes for the validity of the generalizedmore » Marcus formula. The existence of long living quantum coherences at ambient temperatures emerges naturally from our approach.« less

Kinetics and mechanism studies of switching and association reactions involving Na + -ligand complexes

NASA Astrophysics Data System (ADS)

Yang, X.; Castleman, A. W., Jr.

1990-08-01

The kinetics and mechanisms of the reactions of Na+ṡ(X)n=0-3, X=water, ammonia, and methanol with CH3CN, CH3COCH3, CH3CHO, CH3COOH, CH3COOCH3, NH3, CH3OH, and CH3-O-C2H4-O-CH3(DMOE) were studied at ambient temperature under different pressures. All of the switching (substitution) reactions proceed at near-collision rate and show little dependence on the flow tube pressure, the nature and size of the ligand, or the type of core ions. Interestingly, all of the measured rate constants agree well with predictions based on the parametrized trajectory calculations of Su and Chesnavich [J. Chem. Phys. 76, 5183 (1982)]. The reactions of the bare sodium ion with all neutrals proceed via a three-body association mechanism and the measured rate constants cover a large range from a slow association reaction with NH3, to a near-collision rate with DMOE. The lifetimes and the dissociation rate constants of the intermediate complexes deduced using the parametrized trajectory results, combined with the experimentally determined rates, compare fairly well with predictions based on RRKM theory. The calculations also account for the large isotope effect observed for the clustering of ND3 and NH3 to Na+.

Vibrational photochemistry of porphine imbedded in a n-hexane-d sub 14 Shpol'skii matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butenhoff, T.J.; Chuck, R.S.; Limbach, H.H.

The near-infrared-induced tautomerization of free-base porphine incorporated in a n-hexane-d{sub 14} matrix is reported. Porphine occupies two sites in a n-hexane-d{sub 14} matrix as opposed to one site in a n-hexane matrix. Two spectroscopically distinct tautomers, differing by a 90{degree} rotation of the NH bond axes within the molecular plane, exist for each site. Nernst glower irradiation on the NH stretch fundamental does not induce tautomerization, but irradiation in the regions 4,000 < {nu} < 5,100 cm{sup {minus}1} and 5,630 < {nu} < 7,700 cm{sup {minus}1} does induce tautomerization. Narrow-band (8 cm{sup {minus}1} fwhm) laser irradiation studies in the NHmore » symmetric plus antisymmetric stretch combination band region (6,300 < {nu} < 6,600 cm{sup {minus}1}) show that the near-infrared-induced tautomerization occurs at select wavelengths. Tautomer conversion in absence of site conversion is strong evidence that the observed photochemistry is due to absorption of light by porphine and not by hexane. The estimated quantum yield is roughly 5 {times} 10{sup {minus}4} for 6,530-cm{sup {minus}1} irradiation; this is 1-3 orders of magnitude larger than the quantum yield expected from RRKM theory.« less

Theoretical study of the kinetics of chlorine atom abstraction from chloromethanes by atomic chlorine.

PubMed

Brudnik, Katarzyna; Twarda, Maria; Sarzyński, Dariusz; Jodkowski, Jerzy T

2013-10-01

Ab initio calculations at the G3 level were used in a theoretical description of the kinetics and mechanism of the chlorine abstraction reactions from mono-, di-, tri- and tetra-chloromethane by chlorine atoms. The calculated profiles of the potential energy surface of the reaction systems show that the mechanism of the studied reactions is complex and the Cl-abstraction proceeds via the formation of intermediate complexes. The multi-step reaction mechanism consists of two elementary steps in the case of CCl4 + Cl, and three for the other reactions. Rate constants were calculated using the theoretical method based on the RRKM theory and the simplified version of the statistical adiabatic channel model. The temperature dependencies of the calculated rate constants can be expressed, in temperature range of 200-3,000 K as [Formula: see text]. The rate constants for the reverse reactions CH3/CH2Cl/CHCl2/CCl3 + Cl2 were calculated via the equilibrium constants derived theoretically. The kinetic equations [Formula: see text] allow a very good description of the reaction kinetics. The derived expressions are a substantial supplement to the kinetic data necessary to describe and model the complex gas-phase reactions of importance in combustion and atmospheric chemistry.

Infrared conductivity of cuprates using Yang-Rice-Zhang ansatz: Review of our recent investigations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Navinder; Sharma, Raman

2015-05-15

A review of our recent investigations related to the ac transport properties in the psedogapped state of cuprate high temperature superconductors is presented. For our theoretical calculations we use a phenomenological Green’s function proposed by Yang, Rice and Zhang (YRZ). This is based upon the renormalized mean-field theory of the Hubbard model and takes into account the strong electron-electron interaction present in Cuprates. The pseudogap is also taken into account through a proposed self energy. We have tested the form of the Green’s function by computing ac conductivity of cuprates and then compared with experimental results. We found agreement betweenmore » theory and experiment in reproducing the doping evolution of ac conductivity but there is a problem with absolute magnitudes and their frequency dependence. This shows a partial success of the YRZ ansatz. The ways to rectify it are suggested and worked out.« less

Role of coherence and delocalization in photo-induced electron transfer at organic interfaces

NASA Astrophysics Data System (ADS)

Abramavicius, V.; Pranculis, V.; Melianas, A.; Inganäs, O.; Gulbinas, V.; Abramavicius, D.

2016-09-01

Photo-induced charge transfer at molecular heterojunctions has gained particular interest due to the development of organic solar cells (OSC) based on blends of electron donating and accepting materials. While charge transfer between donor and acceptor molecules can be described by Marcus theory, additional carrier delocalization and coherent propagation might play the dominant role. Here, we describe ultrafast charge separation at the interface of a conjugated polymer and an aggregate of the fullerene derivative PCBM using the stochastic Schrödinger equation (SSE) and reveal the complex time evolution of electron transfer, mediated by electronic coherence and delocalization. By fitting the model to ultrafast charge separation experiments, we estimate the extent of electron delocalization and establish the transition from coherent electron propagation to incoherent hopping. Our results indicate that even a relatively weak coupling between PCBM molecules is sufficient to facilitate electron delocalization and efficient charge separation at organic interfaces.

Theoretical investigation of the electron transfer dynamics and photodegradation pathways in a hydrogen-evolving ruthenium-palladium photocatalyst.

PubMed

Staniszewska, Magdalena; Kupfer, Stephan; Guthmuller, Julien

2018-05-16

Time-dependent density functional theory calculations combined with the Marcus theory of electron transfer (ET) were applied on the molecular photocatalyst [(tbbpy)2Ru(tpphz)PdCl2]2+ in order to elucidate the light-induced relaxation pathways populated upon excitation in the longer wavelength range of its absorption spectrum. The computational results show that after the initial excitation, metal (Ru) to ligand (tpphz) charge transfer (MLCT) triplet states are energetically accessible, but that an ET toward the catalytic center (PdCl2) from these states is a slow process, with estimated time constants above 1 ns. Instead, the calculations predict that low-lying Pd-centered states are efficiently populated - associated to an energy transfer toward the catalytic center. Thus, it is postulated that these states lead to the dissociation of a Cl- and are consequently responsible for the experimentally observed degradation of the catalytic center. Following dissociation, it is shown that the ET rates from the MLCT states to the charge separated states are significantly increased (i.e. 10^5-10^6 times larger). This demonstrates that alteration of the catalytic center generates efficient charge separation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

First principles study of the structural, electronic, and transport properties of triarylamine-based nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akande, Akinlolu, E-mail: akandea@tcd.ie; Bhattacharya, Sandip; Cathcart, Thomas

2014-02-21

We investigate with state of the art density functional theory the structural, electronic, and transport properties of a class of recently synthesized nanostructures based on triarylamine derivatives. First, we consider the single molecule precursors in the gas phase and calculate their static properties, namely (i) the geometrical structure of the neutral and cationic ions, (ii) the electronic structure of the frontier molecular orbitals, and (iii) the ionization potential, hole extraction potential, and internal reorganization energy. This initial study does not evidence any direct correlation between the properties of the individual molecules and their tendency to self-assembly. Subsequently, we investigate themore » charge transport characteristics of the triarylamine derivatives nanowires, by using Marcus theory. For one derivative we further construct an effective Hamiltonian including intermolecular vibrations and evaluate the mobility from the Kubo formula implemented with Monte Carlo sampling. These two methods, valid respectively in the sequential hopping and polaronic band limit, give us values for the room-temperature mobility in the range 0.1–12 cm{sup 2}/Vs. Such estimate confirms the superior transport properties of triarylamine-based nanowires, and make them an attracting materials platform for organic electronics.« less

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Difference in oxidative stress tolerance between rice cultivars estimated with chlorophyll fluorescence analysis.

PubMed

Kasajima, Ichiro

2017-04-26

Oxidative stress is considered to be involved in growth retardation of plants when they are exposed to a variety of biotic and abiotic stresses. Despite its potential importance in improving crop production, comparative studies on oxidative stress tolerance between rice (Oryza sativa L.) cultivars are limited. This work describes the difference in term of oxidative stress tolerance between 72 rice cultivars. 72 rice cultivars grown under naturally lit greenhouse were used in this study. Excised leaf discs were subjected to a low concentration of methyl viologen (paraquat), a chemical reagent known to generate reactive oxygen species in chloroplast. Chlorophyll fluorescence analysis using a two-dimensional fluorescence meter, ion leakage analysis as well as the measurement of chlorophyll contents were used to evaluate the oxidative stress tolerance of leaf discs. Furthermore, fluorescence intensities were finely analyzed based on new fluorescence theories that we have optimized. Treatment of leaf discs with methyl viologen caused differential decrease of maximum quantum yield of photosystem II (Fv/Fm) between cultivars. Decrease of Fv/Fm was also closely correlated with increase of ion leakage and decrease of chlorophyll a/b ratio. Fv/Fm was factorized into photochemical and non-photochemical parameters to classify rice cultivars into sensitive and tolerant ones. Among the 72 compared rice cultivars, the traditional cultivar Co13 was identified as the most tolerant to oxidative stress. Koshihikari, a dominant modern Japonica cultivar in Japan as well as IR58, one of the modern Indica breeding lines exhibited a strong tolerance to oxidative stress. Close correlation between Fv/Fm and chlorophyll a/b ratio provides a simple method to estimate oxidative stress tolerance, without measurement of chlorophyll fluorescence with special equipment. The fact that modern cultivars, especially major cultivars possessed tolerance to oxidative stress suggests that oxidative stress tolerance is one of the agricultural traits prerequisite for improvement of modern rice cultivars. Data presented in this study would enable breeding of rice cultivars having strong tolerance to oxidative stress.

Aerospace, Chemical and Material Sciences

DTIC Science & Technology

2012-03-05

Origami , ASDR&E COI Materials, Joint AFOSR/RX/RH Center of Excellence at Georgia Tech on Bio Materials Rice professor’s nanotube theory confirmed...Jason’s Study) • (Schmisseur invited expert and our newest AIAA Fellow!!!) • AFOSR-NSF collaborative agreement & Origami Initiative • (collaborative

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

PubMed

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.

From the Landgrave in Kassel to Isaac Newton

NASA Astrophysics Data System (ADS)

Høg, E.

2018-01-01

Landgrave Wilhelm IV established in 1560 the first permanent astronomical observatory in Europe. When he met the young Tycho Brahe in 1575 he recognized the genius and recommended him warmly to the Danish king Frederik II. Wilhelm and Tycho must share the credit for renewing astronomy with very accurate observations of positions of stars by new instrumentation and new methods. Tycho's observations of planets during 20 years enabled Johannes Kepler to derive the laws of planetary motion. These laws set Isaac Newton in a position to publish the laws of physical motion and universal gravitation in 1687 - the basis for the technical revolution.

Harbouring public good mutants within a pathogen population can increase both fitness and virulence.

PubMed

Lindsay, Richard J; Kershaw, Michael J; Pawlowska, Bogna J; Talbot, Nicholas J; Gudelj, Ivana

2016-12-28

Existing theory, empirical, clinical and field research all predict that reducing the virulence of individuals within a pathogen population will reduce the overall virulence, rendering disease less severe. Here, we show that this seemingly successful disease management strategy can fail with devastating consequences for infected hosts. We deploy cooperation theory and a novel synthetic system involving the rice blast fungus Magnaporthe oryzae . In vivo infections of rice demonstrate that M. oryzae virulence is enhanced, quite paradoxically, when a public good mutant is present in a population of high-virulence pathogens. We reason that during infection, the fungus engages in multiple cooperative acts to exploit host resources. We establish a multi-trait cooperation model which suggests that the observed failure of the virulence reduction strategy is caused by the interference between different social traits. Multi-trait cooperative interactions are widespread, so we caution against the indiscriminant application of anti-virulence therapy as a disease-management strategy.

[The Antonine plague].

PubMed

Haas, Charles

2006-01-01

During the reign of Marcus Aurelius, the Roman Empire was struck by a long and destructive epidemic. It began in Mesopotamia in late AD 165 or early AD 166 during Verus' Parthian campaign, and quickly spread to Rome. It lasted at least until the death of Marcus Aurelius in AD 180 and likely into the early part of Commodus' reign. Its victims were "innumerable". Galen had first-hand knowledge of the disease. He was in Rome when the plague reached the city in AD 166. He was also present during an outbreak among troops stationed at Aquileia during the winter of AD 168-169. His references to the plague are scattered and brief but enough information is available to firmly identify the plague as smallpox. His description of the exanthema is fairly typical of the smallpox rash, particularly in the hemorrhagic phase of the disease.

[The use of opium in Roman society and the dependence of Princeps Marcus Aurelius].

PubMed

Trancas, Bruno; Borja Santos, Nuno; Patrício, Luís D

2008-01-01

Opium was known and frequently used in Roman society. Medical practice recognized its usefulness as an analgesic, soporific, anti-tussic or anti-diarrheic agent, as well as other currently unsupported uses with quasi-magical properties. It was additionally used as an ingredient in antidotes, panaceas and poisons. The authors present a non-exhaustive compilation of opium use according to medical doctors, writers and encyclopaedists of the time. Mythological and literary representations of the opium poppy reflected its diverse roles, being associated with prosperity and fertility, sleep, death and the underworld and with the art of medicine. Despite its free and routine use, there is no solid evidence of addiction, except the putative case of emperor Marcus Aurelius, consistently reported as one of the most likely cases of addiction to opium.

Photoinduced electron transfer in an imidazolium ionic liquid and in its binary mixtures with water, methanol, and 2-propanol: appearance of Marcus-type of inversion.

PubMed

Sarkar, Souravi; Mandal, Sarthak; Ghatak, Chiranjib; Rao, Vishal Govind; Ghosh, Surajit; Sarkar, Nilmoni

2012-02-02

The photoinduced electron transfer (PET) reaction has been investigated in a room temperature imidazolium ionic liquid (RTIL), 1-ethyl-3-methylimidazolium ethyl sulfate ([Emim][EtSO(4)]) and also in [Emim][EtSO(4)]-co-solvents mixtures from N,N-dimethyl aniline (DMA) to different Coumarin dyes using steady state and time-resolved fluorescence quenching measurements. We have used water and methanol and 2-propanol as the cosolvents of RTILs for the PET study. On going from neat ionic liquid to the RTIL-co-solvents mixtures the electron transfer rate has been largely enhanced. In neat RTIL as well as in [Emim][EtSO(4)]-co-solvents mixtures, a Marcus type of inversion in the PET rate have been observed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

H. Nolen, S. Maxwell, R. Neri, J. Grab

This research effort sought to achieve a solution package that yields energy savings greater than 30 percent over the pre-existing conditions in a minimally intrusive multifamily retrofit project. The Consortium for Advanced Residential Buildings (CARB) partnered with L+M Development Partners, Inc. on a Mitchell-Lama Housing Program project, Marcus Garvey Village, in Brooklyn, NY (Climate Zone 4A). The Mitchell-Lama Housing Program is a form of housing subsidy in the state of New York that provides affordable rental and cooperative housing to moderate- and middle-income families. Marcus Garvey Village was founded in 1975 and contains 625 residential units (ranging from studios tomore » 5-bedroom units) in thirty-two 4-story garden-style apartment structures built with concrete and faced in light brown brick. The single largest challenge for implementation of energy conservation measures at Marcus Garvey was working within occupied spaces. Measures are being implemented in phases to minimize disruption. As of August 2015, the retrofit work is over 50 percent complete. The wall insulation, sealing of the through wall AC vent, and installation of new oil-filled electric baseboards with advanced controls are conducted at one time, limiting disruption to the living room space. In a similar fashion, the kitchen work is done, then the bathroom. The final selection of energy conservation measures is projected to save 26.5 percent in source energy with a cost just under $3.7 million and utility bill savings of nearly $480,000 (of an average $1.8 million annual utility cost for the development).« less

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening.

PubMed

Dinh, Thanh-Chung; Renger, Thomas

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. So far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low temperatures, Redfield theory still provides a numerically efficient alternative to NeMoR theory. At higher temperatures, we suggest to use NeMoR theory, because it has the same numerical costs as modified Redfield theory, but is more accurate.

The First Journalism School.

ERIC Educational Resources Information Center

Boyle, Diane

2000-01-01

Offers a brief look at the life of Marcus Walter Williams: his early life and education, his work life in journalism, and his founding of the first school of Journalism (located at the University of Missouri) in 1906. (SR)

A Faculty Trains Itself to Improve Student Discipline

ERIC Educational Resources Information Center

Grantham, Marvin L.; Harris, Clifton S., Jr.

1976-01-01

The Marcus School staff feels that the best approach to discipline is a preventive one--the provision of a variety of educational and environmental alternatives that will interest, challenge, and motivate the pupil. (Author)

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeTuri, V.F.; Ervin, K.M.

Energy-resolved competitive collision-induced dissociation methods are used to measure the gas-phase acidities of a series of alcohols (methanol, ethanol, 2-propanol, and 2-methyl-2-propanol). The competitive dissociation reactions of fluoride-alcohol, [F{sup {minus}}{center{underscore}dot}HOR], alkoxide-water, [RO{sup {minus}}{center{underscore}dot}HOH], and alkoxide-methanol [RO{+-}{center{underscore}dot}HOCH{sub 3}] proton-bound complexes are studied using a guided ion beam tandem mass spectrometer. The reaction cross sections and product branching fractions to the two proton transfer channels are measured as a function of collision energy. The enthalpy difference between the two product channels is found by modeling the reaction cross sections near threshold using RRKM theory to account for the energy-dependent product branching ratiomore » and kinetic shift. From the enthalpy difference, the alcohol gas-phase acidities are determined relative to the well-known values of HF and H{sub 2}O. The measured gas-phase acidities are {Delta}{sub acid}H{sub 298}(CH{sub 3}OH) = 1599 {+-} 3 kJ/mol, {Delta}{sub acid}H{sub 298}(CH{sub 3}CH{sub 2}OH) = 1586 {+-} 5 kJ/mol, {Delta}{sub acid}H{sub 298}((CH{sub 3}){sub 2}CHOH) = 1576 {+-} 4 kJ/mol, and {Delta}{sub acid}H{sub 298}((CH{sub 3}){sub 3}COH) = 1573 {+-} 3 kJ/mol.« less

Time-resolved photoelectron imaging of iodide-nitromethane (I-·CH3NO2) photodissociation dynamics.

PubMed

Kunin, Alice; Li, Wei-Li; Neumark, Daniel M

2016-12-07

Femtosecond time-resolved photoelectron spectroscopy is used to probe the decay channels of iodide-nitromethane (I - ·CH 3 NO 2 ) binary clusters photoexcited at 3.56 eV, near the vertical detachment energy (VDE) of the cluster. The production of I - is observed, and its photoelectron signal exhibits a mono-exponential rise time of 21 ± 1 ps. Previous work has shown that excitation near the VDE of the I - ·CH 3 NO 2 complex transfers an electron from iodide to form a dipole-bound state of CH 3 NO 2 - that rapidly converts to a valence bound (VB) anion. The long appearance time for the I - fragment suggests that the VB anion decays by back transfer of the excess electron to iodide, reforming the I - ·CH 3 NO 2 anion and resulting in evaporation of iodide. Comparison of the measured lifetime to that predicted by RRKM theory suggests that the dissociation rate is limited by intramolecular vibrational energy redistribution in the re-formed anion between the high frequency CH 3 NO 2 vibrational modes and the much lower frequency intermolecular I - ·CH 3 NO 2 stretch and bends, the predominant modes involved in cluster dissociation to form I - . Evidence for a weak channel identified as HI + CH 2 NO 2 - is also observed.

Modeling and Real-Time Process Monitoring of Organometallic Chemical Vapor Deposition of III-V Phosphides and Nitrides at Low and High Pressure

NASA Technical Reports Server (NTRS)

Bachmann, K. J.; Cardelino, B. H.; Moore, C. E.; Cardelino, C. A.; Sukidi, N.; McCall, S.

1999-01-01

The purpose of this paper is to review modeling and real-time monitoring by robust methods of reflectance spectroscopy of organometallic chemical vapor deposition (OMCVD) processes in extreme regimes of pressure. The merits of p-polarized reflectance spectroscopy under the conditions of chemical beam epitaxy (CBE) and of internal transmission spectroscopy and principal angle spectroscopy at high pressure are assessed. In order to extend OMCVD to materials that exhibit large thermal decomposition pressure at their optimum growth temperature we have designed and built a differentially-pressure-controlled (DCP) OMCVD reactor for use at pressures greater than or equal to 6 atm. We also describe a compact hard-shell (CHS) reactor for extending the pressure range to 100 atm. At such very high pressure the decomposition of source vapors occurs in the vapor phase, and is coupled to flow dynamics and transport. Rate constants for homogeneous gas phase reactions can be predicted based on a combination of first principles and semi-empirical calculations. The pressure dependence of unimolecular rate constants is described by RRKM theory, but requires variational and anharmonicity corrections not included in presently available calculations with the exception of ammonia decomposition. Commercial codes that include chemical reactions and transport exist, but do not adequately cover at present the kinetics of heteroepitaxial crystal growth.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowland, F.S.

This report describes the progress in several projects: gas phase substitution reactions of thermal chlorine atoms with tetramethyl metallo-organic compounds; abstraction reactions by thermal chlorine atoms with tetramethyl metallo-organic compounds; gas phase thermal {sup 38}Cl reactions with M(CH{double_bond}CH{sub 2}){sub n}: non-RRKM decomposition of excited radicals (M = Sn, Si, n = 4; M = Sb, n = 3; M = Hg, n = 2); quantitative product identification for reactions of hydroxyl with {sup 14}CS{sub 2}; and statistical analysis of ground-based measurements of total ozone with Dobson spectrometers. The report also contains a research proposal for work from May, 1991 throughmore » April, 1992.« less

78 FR 24798 - Qualification of Drivers; Exemption Applications; Vision

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-26

... exceeded the speed limit by 13 mph. Marcus R. Watkins Mr. Watkins, 50, has had a retinal detachment in his... vision to perform driving tasks required to operate a commercial vehicle.'' Mr. Watkins reported that he...

Adiabatic elimination for systems with inertia driven by compound Poisson colored noise.

PubMed

Li, Tiejun; Min, Bin; Wang, Zhiming

2014-02-01

We consider the dynamics of systems driven by compound Poisson colored noise in the presence of inertia. We study the limit when the frictional relaxation time and the noise autocorrelation time both tend to zero. We show that the Itô and Marcus stochastic calculuses naturally arise depending on these two time scales, and an extra intermediate type occurs when the two time scales are comparable. This leads to three different limiting regimes which are supported by numerical simulations. Furthermore, we establish that when the resulting compound Poisson process tends to the Wiener process in the frequent jump limit the Itô and Marcus calculuses, respectively, tend to the classical Itô and Stratonovich calculuses for Gaussian white noise, and the crossover type calculus tends to a crossover between the Itô and Stratonovich calculuses. Our results would be very helpful for understanding relevant experiments when jump type noise is involved.

Model of a thin film optical fiber fluorosensor

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1991-01-01

The efficiency of core-light injection from sources in the cladding of an optical fiber is modeled analytically by means of the exact field solution of a step-profile fiber. The analysis is based on the techniques by Marcuse (1988) in which the sources are treated as infinitesimal electric currents with random phase and orientation that excite radiation fields and bound modes. Expressions are developed based on an infinite cladding approximation which yield the power efficiency for a fiber coated with fluorescent sources in the core/cladding interface. Marcuse's results are confirmed for the case of a weakly guiding cylindrical fiber with fluorescent sources uniformly distributed in the cladding, and the power efficiency is shown to be practically constant for variable wavelengths and core radii. The most efficient fibers have the thin film located at the core/cladding boundary, and fibers with larger differences in the indices of refraction are shown to be the most efficient.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chęcińska, Agata; Heaney, Libby; Pollock, Felix A.

Motivated by a proposed olfactory mechanism based on a vibrationally activated molecular switch, we study electron transport within a donor-acceptor pair that is coupled to a vibrational mode and embedded in a surrounding environment. We derive a polaron master equation with which we study the dynamics of both the electronic and vibrational degrees of freedom beyond previously employed semiclassical (Marcus-Jortner) rate analyses. We show (i) that in the absence of explicit dissipation of the vibrational mode, the semiclassical approach is generally unable to capture the dynamics predicted by our master equation due to both its assumption of one-way (exponential) electronmore » transfer from donor to acceptor and its neglect of the spectral details of the environment; (ii) that by additionally allowing strong dissipation to act on the odorant vibrational mode, we can recover exponential electron transfer, though typically at a rate that differs from that given by the Marcus-Jortner expression; (iii) that the ability of the molecular switch to discriminate between the presence and absence of the odorant, and its sensitivity to the odorant vibrational frequency, is enhanced significantly in this strong dissipation regime, when compared to the case without mode dissipation; and (iv) that details of the environment absent from previous Marcus-Jortner analyses can also dramatically alter the sensitivity of the molecular switch, in particular, allowing its frequency resolution to be improved. Our results thus demonstrate the constructive role dissipation can play in facilitating sensitive and selective operation in molecular switch devices, as well as the inadequacy of semiclassical rate equations in analysing such behaviour over a wide range of parameters.« less

Retrofitting Garden-Style Apartments in Brooklyn, New York

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nolen, Heather; Maxwell, Sean; Neri, Robin

This research effort sought to achieve a solution package that yields energy savings greater than 30% over the pre-existing conditions in a minimally intrusive multifamily retrofit project. The Consortium for Advanced Residential Buildings (CARB) partnered with L+M Development Partners, Inc. on a Mitchell-Lama Housing Program project, Marcus Garvey Village, in Brooklyn, NY (Climate Zone 4A). The Mitchell-Lama Housing Program is a form of housing subsidy in the state of New York that provides affordable rental and cooperative housing to moderate- and middle-income families. Marcus Garvey Village was founded in 1975 and contains 625 residential units (ranging from studios to 5-bedroommore » units) in thirty-two 4-story garden-style apartment structures built with concrete and faced in light brown brick. The single largest challenge for implementation of energy conservation measures at Marcus Garvey was working within occupied spaces. Measures are being implemented in phases to minimize disruption. As of August 2015, the retrofit work is over 50% complete. The wall insulation, sealing of the through wall AC vent, and installation of new oil-filled electric baseboards with advanced controls are conducted at one time, limiting disruption to the living room space. In a similar fashion, the kitchen work is done, then the bathroom. The final selection of energy conservation measures is projected to save 26.5% in source energy with a cost just under $3.7 million and utility bill savings of nearly $480,000 (of an average $1.8 million annual utility cost for the development).« less

Building America Case Study: Retrofitting Garden-Style Apartments, Brooklyn, New York

DOE Office of Scientific and Technical Information (OSTI.GOV)

This research effort sought to achieve a solution package that yields energy savings greater than 30 percent over the pre-existing conditions in a minimally intrusive multifamily retrofit project. The Consortium for Advanced Residential Buildings (CARB) partnered with L+M Development Partners, Inc. on a Mitchell-Lama Housing Program project, Marcus Garvey Village, in Brooklyn, NY (Climate Zone 4A). The Mitchell-Lama Housing Program is a form of housing subsidy in the state of New York that provides affordable rental and cooperative housing to moderate- and middle-income families. Marcus Garvey Village was founded in 1975 and contains 625 residential units (ranging from studios tomore » 5-bedroom units) in thirty-two 4-story garden-style apartment structures built with concrete and faced in light brown brick. The single largest challenge for implementation of energy conservation measures at Marcus Garvey was working within occupied spaces. Measures are being implemented in phases to minimize disruption. As of August 2015, the retrofit work is over 50 percent complete. The wall insulation, sealing of the through wall AC vent, and installation of new oil-filled electric baseboards with advanced controls are conducted at one time, limiting disruption to the living room space. In a similar fashion, the kitchen work is done, then the bathroom. The final selection of energy conservation measures is projected to save 26.5 percent in source energy with a cost just under $3.7 million and utility bill savings of nearly $480,000 (of an average $1.8 million annual utility cost for the development).« less

Density Functional Study on A-Units Based on Thieno[3,4- c]pyrrole-4,6-dione for Organic Solar Cells

NASA Astrophysics Data System (ADS)

Tang, Xiaoqin; Shen, Wei; Fu, Zhiyong; Liu, Xiaorui; Li, Ming

2017-08-01

The use of polymer donor materials has allowed great progress in organic solar cells. To search for potential donor materials, we have designed a series of donor-acceptor (D-A)-type alternating polymers composed of dithieno[3,2- b:2',3'- d]pyrrole (DTP) electron-rich units and thieno[3,4- c]pyrrole-4,6-dione (TPD) electron-deficient units. Their electronic and optical properties have been investigated using density functional theory and Marcus theory. The calculation results demonstrate that introduction of cyclic compounds (furyl, thienyl, and phenyl) into electron-deficient units of the molecules can result in lower highest occupied molecular orbital (HOMO) levels and reorganization energies compared with the experimental molecule ( X 0 ). To investigate the effects of electron-withdrawing units, three electron-withdrawing substituents (-OCH3, -F, and -CN) were introduced into the thienyl. The results indicated that the polymer X 2-3 will show the best performance among the designed polymers, offering low-lying HOMO energy level (-5.47 eV), narrow energy gap (1.97 eV), and high hole mobility (7.45 × 10-2 cm2 V-1 s-1). This work may provide a guideline for the design of efficient D-A polymers for organic solar cells with enhanced performance.

The isotopic effects of electron transfer: An explanation for Fe isotope fractionation in nature

NASA Astrophysics Data System (ADS)

Kavner, Abby; Bonet, François; Shahar, Anat; Simon, Justin; Young, Edward

2005-06-01

Isotope fractionation of electroplated Fe was measured as a function of applied electrochemical potential. As plating voltage was varied from -0.9 V to 2.0 V, the isotopic signature of the electroplated iron became depleted in heavy Fe, with δ 56Fe values (relative to IRMM-14) ranging from -0.18(±0.02) to -2.290(±0.006) ‰, and corresponding δ 57Fe values of -0.247(±0.014) and -3.354(±0.019) ‰. This study demonstrates that there is a voltage-dependent isotope fractionation associated with the reduction of iron. We show that Marcus's theory for the kinetics of electron transfer can be extended to include the isotope effects of electron transfer, and that the extended theory accounts for the voltage dependence of Fe isotope fractionation. The magnitude of the electrochemically-induced fractionation is similar to that of Fe reduction by certain bacteria, suggesting that similar electrochemical processes may be responsible for biogeochemical Fe isotope effects. Charge transfer is a fundamental physicochemical process involving Fe as well as other transition metals with multiple isotopes. Partitioning of isotopes among elements with varying redox states holds promise as a tool in a wide range of the Earth and environmental sciences, biology, and industry.

MutY: optimized to find DNA damage site electronically?

NASA Astrophysics Data System (ADS)

Lin, Jong-Chin; Cox, Daniel; Singh, Rajiv

2006-03-01

Iron sulfur clusters are present in the DNA repair protein MutY in a region highly homologous in species as diverse as E. Coli and Homo Sapiens, yet their function remains unknown. In MutY, this mixed valence cluster exists in two oxidation states, [Fe4S4]^2+/3+, with the stability depending upon the presence of DNA. We have studied the electronic structure and stability of these clusters using the local orbital based SIESTA implementation of density functional theory. We find that the iron-sulfur cluster in MutY can undergo 2+ to 3+ oxidation when coupling to DNA through hole transfer, especially when MutY is near an oxoguanine modified base(oxoG). Employing the Marcus theory for electron transfer, we find (i) near optimal Frank-Condon(FC) factor for 2+ transfer to oxoG; (ii) reduced FC factor for transfer to G due to a high oxidation potential; (iii) reduced FC factor with the mutation L154F; (iv) reduced tunning matrix element with the mutation R149W. Both L154F and R149W mutations dramatically reduce or eliminate repair efficiency. Hence, redox modulation of MutY search and binding appears plausible and may have broader implications for DNA-protein interactions.

Modeling the free energy surfaces of electron transfer in condensed phases

NASA Astrophysics Data System (ADS)

Matyushov, Dmitry V.; Voth, Gregory A.

2000-10-01

We develop a three-parameter model of electron transfer (ET) in condensed phases based on the Hamiltonian of a two-state solute linearly coupled to a harmonic, classical solvent mode with different force constants in the initial and final states (a classical limit of the quantum Kubo-Toyozawa model). The exact analytical solution for the ET free energy surfaces demonstrates the following features: (i) the range of ET reaction coordinates is limited by a one-sided fluctuation band, (ii) the ET free energies are infinite outside the band, and (iii) the free energy surfaces are parabolic close to their minima and linear far from the minima positions. The model provides an analytical framework to map physical phenomena conflicting with the Marcus-Hush two-parameter model of ET. Nonlinear solvation, ET in polarizable charge-transfer complexes, and configurational flexibility of donor-acceptor complexes are successfully mapped onto the model. The present theory leads to a significant modification of the energy gap law for ET reactions.

Crucial role of decoherence for electronic transport in molecular wires: Polyaniline as a case study

NASA Astrophysics Data System (ADS)

Cattena, Carlos J.; Bustos-Marún, Raúl A.; Pastawski, Horacio M.

2010-10-01

In this work we attempt to elucidate the nature of conductivity in polymers by taking the acid-base doped polyaniline (PAni) polymer. We evaluate the PAni conductance by using realistic ab initio parameters and including decoherent processes within the minimal parametrization model of D’Amato-Pastawski. In contrast to general wisdom, which associates the conducting state with coherent propagation in a periodic polaronic lattice, we show that decoherence can account for high conductance in the strongly disordered bipolaronic lattice. Hence, according to our results, there is no need of considering a mix model of “conducting” polaronic lattice islands separated by “insulating” bipolaronic lattice strands as is usually assumed for PAni. We find that without dephasing events, even very short strands of bipolaronic lattices are not able to sustain electronic transport. We also include a discussion of specific mechanisms that should be involved in decoherence rates of PAni and relate them with Marcus-Hush theory of electron transfer.

Theoretical study on the electronic structures and phosphorescent properties of four Ir(III) complexes with different substituents on the ancillary ligand

NASA Astrophysics Data System (ADS)

Han, Deming; Shang, Xiaohong; Zhang, Gang; Zhao, Lihui

2013-12-01

The geometry structures, electronic structures, absorption and phosphorescent properties of four Ir(III) complexes {[(F2-ppy)2Ir(pta-X)], where F2-ppy = (2,4-difluoro)phenylpyridine; pta = pyridine-1,2,4-triazole; X = -CF3; -H; -CH3; -N(CH3)2}, are investigated using the density functional method. The results reveal that the electron-accepting group -CF3 has no obvious effect on absorption and emission properties, while the substitutive group -N(CH3)2 with strong electron-donating ability has obvious effect on the emission properties. The mobility of hole and electron were studied computationally based on the Marcus-Hush theory. Calculations of ionisation potential and electron affinity were used to evaluate the injection abilities of holes and electrons into these complexes. We hope that this theoretical work can provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes.

Hydrogen bonding effects on the reorganization energy for photoinduced charge separation reaction between porphyrin and quinone studied by nanosecond laser flash photolysis.

PubMed

Yago, Tomoaki; Gohdo, Masao; Wakasa, Masanobu

2010-02-25

Alcohol concentration dependences of photoinduced charge separation (CS) reaction of zinc tetraphenyl-porphyrin (ZnTPP) and duroquinone (DQ) were investigated in benzonitrile by a nanosecond laser flash photolysis technique. The photoinduced CS reaction was accelerated by the addition of alcohols, whereas the addition of acetonitrile caused little effect on the CS reactions. The simple theory was developed to calculate an increase in reorganization energies induced by the hydrogen bonding interactions between DQ and alcohols using the chemical equilibrium constants for the hydrogen bonding complexes through the concerted pathway and the stepwise one. The experimental results were analyzed by using the Marcus equation where we took into account the hydrogen bonding effects on the reorganization energy and the reaction free energy for the CS reaction. The observed alcohol concentration dependence of the CS reaction rates was well explained by the formation of the hydrogen bonding complexes through the concerted pathway, demonstrating the increase in the reorganization energy by the hydrogen bonding interactions.

Molecular origin of differences in hole and electron mobility in amorphous Alq3--a multiscale simulation study.

PubMed

Fuchs, Andreas; Steinbrecher, Thomas; Mommer, Mario S; Nagata, Yuki; Elstner, Marcus; Lennartz, Christian

2012-03-28

In order to determine the molecular origin of the difference in electron and hole mobilities of amorphous thin films of Alq(3) (meridional Alq(3) (tris(8-hydroxyquinoline) aluminium)) we performed multiscale simulations covering quantum mechanics, molecular mechanics and lattice models. The study includes realistic disordered morphologies, polarized site energies to describe diagonal disorder, quantum chemically calculated transfer integrals for the off-diagonal disorder, inner sphere reorganization energies and an approximative scheme for outer sphere reorganization energies. Intermolecular transfer rates were calculated via Marcus-theory and mobilities were simulated via kinetic Monte Carlo simulations and by a Master Equation approach. The difference in electron and hole mobility originates from the different localization of charge density in the radical anion (more delocalized) compared to the radical cation (more confined). This results in higher diagonal disorder for holes and less favourable overlap properties for the hole transfer integrals leading to an overall higher electron mobility.

Catalysis-Enhancement via Rotary Fluctuation of F1-ATPase

PubMed Central

Watanabe, Rikiya; Hayashi, Kumiko; Ueno, Hiroshi; Noji, Hiroyuki

2013-01-01

Protein conformational fluctuations modulate the catalytic powers of enzymes. The frequency of conformational fluctuations may modulate the catalytic rate at individual reaction steps. In this study, we modulated the rotary fluctuation frequency of F1-ATPase (F1) by attaching probes with different viscous drag coefficients at the rotary shaft of F1. Individual rotation pauses of F1 between rotary steps correspond to the waiting state of a certain elementary reaction step of ATP hydrolysis. This allows us to investigate the impact of the frequency modulation of the rotary fluctuation on the rate of the individual reaction steps by measuring the duration of rotation pauses. Although phosphate release was significantly decelerated, the ATP-binding and hydrolysis steps were less sensitive or insensitive to the viscous drag coefficient of the probe. Brownian dynamics simulation based on a model similar to the Sumi-Marcus theory reproduced the experimental results, providing a theoretical framework for the role of rotational fluctuation in F1 rate enhancement. PMID:24268150

Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor.

PubMed

Horke, Daniel A; Li, Quansong; Blancafort, Lluís; Verlet, Jan R R

2013-08-01

Quinones feature prominently as electron acceptors in nature. Their electron-transfer reactions are often highly exergonic, for which Marcus theory predicts reduced electron-transfer rates because of a free-energy barrier that occurs in the inverted region. However, the electron-transfer kinetics that involve quinones can appear barrierless. Here, we consider the intrinsic properties of the para-benzoquinone radical anion, which serves as the prototypical electron-transfer reaction product involving a quinone-based acceptor. Using time-resolved photoelectron spectroscopy and ab initio calculations, we show that excitation at 400 and 480 nm yields excited states that are unbound with respect to electron loss. These excited states are shown to decay on a sub-40 fs timescale through a series of conical intersections with lower-lying excited states, ultimately to form the ground anionic state and avoid autodetachment. From an isolated electron-acceptor perspective, this ultrafast stabilization mechanism accounts for the ability of para-benzoquinone to capture and retain electrons.

NiO: correlated band structure of a charge-transfer insulator.

PubMed

Kunes, J; Anisimov, V I; Skornyakov, S L; Lukoyanov, A V; Vollhardt, D

2007-10-12

The band structure of the prototypical charge-transfer insulator NiO is computed by using a combination of an ab initio band structure method and the dynamical mean-field theory with a quantum Monte-Carlo impurity solver. Employing a Hamiltonian which includes both Ni d and O p orbitals we find excellent agreement with the energy bands determined from angle-resolved photoemission spectroscopy. This brings an important progress in a long-standing problem of solid-state theory. Most notably we obtain the low-energy Zhang-Rice bands with strongly k-dependent orbital character discussed previously in the context of low-energy model theories.

Remediation System Evaluation, SMS Instruments Superfund Site

EPA Pesticide Factsheets

The SMS Instruments Superfund Site is located at 120 Marcus Boulevard in Deer Park, Suffolk County,New York. The site consists of a 34,000 square foot building located on a 1.5-acre lot that is surroundedby other light industrial facilities.

Australian DefenceScience. Volume 13, Number 2, Winter

DTIC Science & Technology

2005-01-01

has been marketing the OAVD technology through its Business and Commercialisation Office (BCO). Marcus Belder, Technology Commercialisation Manager...for ADF organisational structures, and training and education initiatives.” The inquiry process As one line of inquiry, the team has been carrying

Tuskegee Institute in the 1920's

ERIC Educational Resources Information Center

Marable, Manning

1977-01-01

During the time of Marcus Garvey, the Harlem Renaissance and Southern black labor militancy, Tuskegee perpetuated a conservative social philosophy. This contradictory legacy set the stage for a confrontation between the black middle class of Tuskegee and a white racist society. (Author/GC)

Does Harcus-Hush theory really work The solvent dependence of intervalence charge-transfer energetics in (NH[sub 3])[sub 5]Ru[sup II]-4,4'-bipyridine-Ru[sup III](NH[sub 3] )[sub 5][sup 5+] in the limit of infinite dilution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hupp, J.T.; Dong, Y.; Blackbourn, R.L.

1993-04-01

Because of concern about ion-pairing artifacts, the solvent dependence of the intervalence charge-transfer absorption energy for a prototypical mixed-valence system, (NH[sub 3])[sub 5]Ru[sup III]-4,4'-bipyridine-Ru[sup II](NH[sub 3])[sub 5][sup 5+], has been reexamined in the limit of infinite dilution. New data are reported for 14 solvents. While one of these (hexamethylphosphoramide) yields anomalous energetics, the absorption energies for the remaining 13 solvents agree qualitatively with the predictions of the Marcus-Hush theory (i.e., two-sphere dielectric continuum theory). On a quantitative basis, however, there is substantial disagreement with theory, at least when the charge-transfer distance is equated with the metal-to-metal separation distance (as conventionallymore » done). Replacement of this distance with a much shorter distance inferred from by electronic Stark-effect spectroscopy leads to a 3-fold decrease in the magnitude of calculated solvent reorganizational contributions to the overall intervalence energy (and therefore, very good agreement with experiment). Unfortunately, the use of such a short charge-transfer distance (d = 5.1 [+-] 0.7 A) also leads to a violation of one of the boundary conditions for use of the two-sphere model. Reformulation of the problem in terms of a generalized dipole-inversion, dielectric cavity problem, however, leads to nearly perfect agreement between theory and experiment. Additional analysis shows that experiment now also agrees reasonably well with theory regarding the magnitude of solvent-independent energy contributions. Finally, it is noted that downward revision in the estimated charge-transfer distance (from 11.3 to 5.1 A) leads to a substantial upward revision in the experimental (i.e., oscillator-strength based) estimate of the electronic coupling element, H[sub if], for intervalence transfer. 33 refs., 3 figs., 2 tabs.« less

The fragmentation of ethanol cation under an electric field: An ab initio/RRKM study

NASA Astrophysics Data System (ADS)

Lu, Hsiu-Feng; Li, F.-Y.; Lin, Chun-Chin; Nagaya, K.; Chao, Ito; Lin, S. H.

2007-08-01

We present a theoretical study of ethanol cation under an electric field due to the existence of laser field in order to understand the influence of electric field on the mass spectrum of ethanol. The electric field was applied to the four major reaction channels of an ethanol cation, such as the conversion between C 2H 5OH + and c-C 2H 5OH +, CH 3-elimination and two α-H-eliminations, respectively. The correlation between product distribution and field strength is quite complex due to the different responses of the reactants and transition states toward the external electric field. This makes the product distribution change as field strength varies.

STS-127 Crew Visit to Anne Beers Elementary

NASA Image and Video Library

2009-09-23

Students, including Marcus Pratt, left, and Ajani Young, second from left, pay close attention as the crew from STS-127 makes their presentation during a visit to Anne Beers Elementary school, Thursday, Sept. 24, 2009, in Washington. Photo Credit: (NASA/Paul E. Alers)

Education on Trial. Strategies for the Future.

ERIC Educational Resources Information Center

Johnston, William J., Ed.

Problems and opportunities in educational reform at all educational levels are considered in this collection of 18 articles. Titles and authors are as follows: Introduction (William J. Johnston); "Evidence of Decline in Educational Standards" (Philip N. Marcus); "Standards--by What Criteria?" (Francis Keppel); "Educational…

Firing back: how great leaders rebound after career disasters.

PubMed

Sonnenfeld, Jeffrey A; Ward, Andrew J

2007-01-01

Among the tests of a leader, few are more challenging-and more painful-than recovering from a career catastrophe. Most fallen leaders, in fact, don't recover. Still, two decades of consulting experience, scholarly research, and their own personal experiences have convinced the authors that leaders can triumph over tragedy--if they do so deliberately. Great business leaders have much in common with the great heroes of universal myth, and they can learn to overcome profound setbacks by thinking in heroic terms. First, they must decide whether or not to fight back. Either way, they must recruit others into their battle. They must then take steps to recover their heroic status, in the process proving, both to others and to themselves, that they have the mettle necessary to recover their heroic mission. Bernie Marcus exemplifies this process. Devastated after Sandy Sigoloff ired him from Handy Dan, Marcus decided to forgo the distraction of litigation and instead make the marketplace his batttleground. Drawing from his network of carefully nurtured relationships with both close and more distant acquaintances, Marcus was able to get funding for a new venture. He proved that he had the mettle, and recovered his heroic status, by building Home Depot, whose entrepreneurial spirit embodied his heroic mission. As Bank One's Jamie Dimon, J.Crew's Mickey Drexler, and even Jimmy Carter, Martha Stewart, and Michael Milken have shown, stunning comebacks are possible in all industries and walks of life. Whatever the cause of your predicament, it makes sense to get your story out. The alternative is likely to be long-lasting unemployment. If the facts of your dismissal cannot be made public because they are damning, then show authentic remorse. The public is often enormously forgiving when it sees genuine contrition and atonement.

Predicting surface scatter using a linear systems formulation of non-paraxial scalar diffraction

NASA Astrophysics Data System (ADS)

Krywonos, Andrey

Scattering effects from rough surfaces are non-paraxial diffraction phenomena resulting from random phase variations in the reflected wavefront. The ability to predict these effects is important in a variety of applications including x-ray and EUV imaging, the design of stray light rejection systems, and reflection modeling for rendering realistic scenes and animations of physical objects in computer graphics. Rayleigh-Rice (small perturbation method) and Beckmann-Kirchoff (Kirchhoff approximation) theories are commonly used to predict surface scatter effects. In addition, Harvey and Shack developed a linear systems formulation of surface scatter phenomena in which the scattering behavior is characterized by a surface transfer function. This treatment provided insight and understanding not readily gleaned from the two previous theories, and has been incorporated into a variety of computer software packages (ASAP, Zemax, Tracepro). However, smooth surface and paraxial approximations have severely limited the range of applicability of each of the above theoretical treatments. In this dissertation, a linear systems formulation of non-paraxial scalar diffraction theory is first developed and then applied to sinusoidal phase gratings, resulting in diffraction efficiency predictions far more accurate than those provided by classical scalar theories. The application of the theory to these gratings was motivated by the fact that rough surfaces are frequently modeled as a superposition of sinusoidal surfaces of different amplitudes, periods, and orientations. The application of the non-paraxial scalar diffraction theory to surface scatter phenomena resulted first in a modified Beckmann-Kirchhoff surface scattering model, then a generalized Harvey-Shack theory, both of which produce accurate results for rougher surfaces than the Rayleigh-Rice theory and for larger incident and scattering angles than the classical Beckmann-Kirchhoff theory. These new developments enable the analysis and simplify the understanding of wide-angle scattering behavior from rough surfaces illuminated at large incident angles. In addition, they provide an improved BRDF (Bidirectional Reflectance Distribution Function) model, particularly for the smooth surface inverse scattering problem of determining surface power spectral density (PSD) curves from BRDF measurements.

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinh, Thanh-Chung; Renger, Thomas, E-mail: thomas.renger@jku.at

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. Somore » far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low temperatures, Redfield theory still provides a numerically efficient alternative to NeMoR theory. At higher temperatures, we suggest to use NeMoR theory, because it has the same numerical costs as modified Redfield theory, but is more accurate.« less

Repressive Tolerance and the Practice of Adult Education

ERIC Educational Resources Information Center

Brookfield, Stephen D.

2014-01-01

Herbert Marcuse's concept of repressive tolerance argues that behind the justification of tolerance lies the possibility of ideological domination. Tolerance allows intolerable practices to go unchallenged and flattens discussion to assume all viewpoints have equal validity. When alternative, dissenting views are inserted into the curriculum…

The Good Fight: from Plessy to Brown.

ERIC Educational Resources Information Center

Quarles, Benjamin

1979-01-01

The work of Black leaders and organizations from 1896 to 1954 is reviewed. Discussed are Booker T. Washington, W.E.B. DuBois, the NAACP, the National Urban League, Marcus Garvey, Arthur A. Schomberg, Carter G. Woodson, Charles S. Johnson, and A. Philip Randolph. (MC)

Chemistry Research of Optical Fibers.

DTIC Science & Technology

1982-09-27

BROADENING IN OPTICAL FIBERS Herbert B. Rosenstock* Naval Research Laboratory Washington, DC 20375 ABSTRACT A light pulse transmitted through a fiber...Marcatili, Marcuse , and Personick, "Dispersion Properties of Fibers" (Ch. 4 in "Optical Fiber Telecommunications," S. E. Miller and A. C. Chynoweth, eds

Tuning the driving force for exciton dissociation in single-walled carbon nanotube heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ihly, Rachelle; Mistry, Kevin S.; Ferguson, Andrew J.

2016-04-25

Understanding the kinetics and energetics of interfacial electron transfer in molecular systems is crucial for the development of a broad array of technologies, including photovoltaics, solar fuel systems and energy storage. The Marcus formulation for electron transfer relates the thermodynamic driving force and reorganization energy for charge transfer between a given donor/acceptor pair to the kinetics and yield of electron transfer. Here we investigated the influence of the thermodynamic driving force for photoinduced electron transfer (PET) between single-walled carbon nanotubes (SWCNTs) and fullerene derivatives by employing time-resolved microwave conductivity as a sensitive probe of interfacial exciton dissociation. For the firstmore » time, we observed the Marcus inverted region (in which driving force exceeds reorganization energy) and quantified the reorganization energy for PET for a model SWCNT/acceptor system. The small reorganization energies (about 130 meV, most of which probably arises from the fullerene acceptors) are beneficial in minimizing energy loss in photoconversion schemes.« less

Broadband calibration of the R/V Marcus G. Langseth four-string seismic sources

NASA Astrophysics Data System (ADS)

Tolstoy, M.; Diebold, J.; Doermann, L.; Nooner, S.; Webb, S. C.; Bohnenstiehl, D. R.; Crone, T. J.; Holmes, R. C.

2009-08-01

The R/V Marcus G. Langseth is the first 3-D seismic vessel operated by the U.S. academic community. With up to a four-string, 36-element source and four 6-km-long solid state hydrophone arrays, this vessel promises significant new insights into Earth science processes. The potential impact of anthropogenic sound sources on marine life is an important topic to the marine seismic community. To ensure that operations fully comply with existing and future marine mammal permitting requirements, a calibration experiment was conducted in the Gulf of Mexico in 2007-2008. Results are presented from deep (˜1.6 km) and shallow (˜50 m) water sites, obtained using the full 36-element (6600 cubic inches) seismic source. This array configuration will require the largest safety radii, and the deep and shallow sites provide two contrasting operational environments. Results show that safety radii and the offset between root-mean-square and sound exposure level measurements were highly dependent on water depth.

HO + CO reaction rates and H/D kinetic isotope effects: master equation models with ab initio SCTST rate constants.

PubMed

Weston, Ralph E; Nguyen, Thanh Lam; Stanton, John F; Barker, John R

2013-02-07

Ab initio microcanonical rate constants were computed using Semi-Classical Transition State Theory (SCTST) and used in two master equation formulations (1D, depending on active energy with centrifugal corrections, and 2D, depending on total energy and angular momentum) to compute temperature-dependent rate constants for the title reactions using a potential energy surface obtained by sophisticated ab initio calculations. The 2D master equation was used at the P = 0 and P = ∞ limits, while the 1D master equation with centrifugal corrections and an empirical energy transfer parameter could be used over the entire pressure range. Rate constants were computed for 75 K ≤ T ≤ 2500 K and 0 ≤ [He] ≤ 10(23) cm(-3). For all temperatures and pressures important for combustion and for the terrestrial atmosphere, the agreement with the experimental rate constants is very good, but at very high pressures and T ≤ 200 K, the theoretical rate constants are significantly smaller than the experimental values. This effect is possibly due to the presence in the experiments of dimers and prereactive complexes, which were not included in the model calculations. The computed H/D kinetic isotope effects are in acceptable agreement with experimental data, which show considerable scatter. Overall, the agreement between experimental and theoretical H/D kinetic isotope effects is much better than in previous work, and an assumption of non-RRKM behavior does not appear to be needed to reproduce experimental observations.

Shock tube study of dissociation and relaxation in 1,1-difluoroethane and vinyl fluoride.

PubMed

Xu, Hui; Kiefer, John H; Sivaramakrishnan, Raghu; Giri, Binod R; Tranter, Robert S

2007-08-21

This paper reports measurements of the thermal dissociation of 1,1-difluoroethane in the shock tube. The experiments employ laser-schlieren measurements of rate for the dominant HF elimination using 10% 1,1-difluoroethane in Kr over 1500-2000 K and 43 < P < 424 torr. The vinyl fluoride product of this process then dissociates affecting the late observations. We thus include a laser schlieren study (1717-2332 K, 75 < P < 482 torr in 10 and 4% vinyl fluoride in Kr) of this dissociation. This latter work also includes a set of experiments using shock-tube time-of-flight mass spectrometry (4% vinyl fluoride in neon, 1500-1980 K, 500 < P < 1300 torr). These time-of-flight experiments confirm the theoretical expectation that the only reaction in vinyl fluoride is HF elimination. The dissociation experiments are augmented by laser schlieren measurements of vibrational relaxation (1-20% C(2)H(3)F in Kr, 415-1975 K, 5 < P < 50 torr, and 2 and 5% C(2)H(4)F(2) in Kr, 700-1350 K, 6 < P < 22 torr). These experiments exhibit very rapid relaxation, and incubation delays should be negligible in dissociation. An RRKM model of dissociation in 1,1-difluoroethane based on a G3B3 calculation of barrier and other properties fits the experiments but requires a very large DeltaE(down) of 1600 cm(-1), similar to that found in a previous examination of 1,1,1-trifluoroethane. Dissociation of vinyl fluoride is complicated by the presence of two parallel HF eliminations, both three-center and four-center. Structure calculations find nearly equal barriers for these, and TST calculations show almost identical k(infinity). An RRKM fit to the observed falloff again requires an unusually large DeltaE(down) and the experiments actually support a slightly reduced barrier. These large energy-transfer parameters now seem routine in these large fluorinated species. It is perhaps a surprising result for which there is as yet no explanation.

Talking Circles Promote Equitable Discourse

ERIC Educational Resources Information Center

Hung, Marcus

2015-01-01

Teachers facilitate math talk in the classroom, but introducing a structured discussion format called the "talking circle" can influence opportunities for equitable student participation. Drawing on his reflections over the 2013-14 academic year and reviewing his detailed teaching notes and lesson plans, Marcus Hung takes a close look at…

Innovation and Creativity.

ERIC Educational Resources Information Center

1998

This document contains four papers from a symposium on innovation and creativity and their relationship to human resource development (HRD). "Intrapreneurial Programs and Their Impact on Sales, Profit, and Return to Investors" (Melissa H. Marcus, Dennis G. Tesolowski, Clinton H. Isbell) reports on a study in which 100 of 217 randomly…

22. Photocopy of architectural drawing. (Original is in the collection ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Photocopy of architectural drawing. (Original is in the collection of Richard F. McCann, Pasadena, CA.) Site Plan (Untitled). Dated May 3, 1934. Race Course for Mr. Joseph Gottstein, Washington Jockey Club. B. Marcus Priteca. - Longacres, 1621 Southwest Sixteenth Street, Renton, King County, WA

Emergy evaluation of the contribution of irrigation water, and its utilization, in three agricultural systems in China

NASA Astrophysics Data System (ADS)

Chen, Dan; Luo, Zhaohui; Webber, Michael; Chen, Jing; Wang, Weiguang

2014-09-01

Emergy theory and method are used to evaluate the contribution of irrigation water, and the process of its utilization, in three agricultural systems. The agricultural systems evaluated in this study were rice, wheat, and oilseed rape productions in an irrigation pumping district of China. A corresponding framework for emergy evaluation and sensitivity analysis methods was proposed. Two new indices, the fraction of irrigation water ( FIW), and the irrigation intensity of agriculture ( IIA), were developed to depict the contribution of irrigation water. The calculated FIW indicated that irrigation water used for the rice production system (34.7%) contributed more than irrigation water used for wheat (5.3%) and oilseed rape (11.2%) production systems in a typical dry year. The wheat production with an IIA of 19.0 had the highest net benefit from irrigation compared to the rice (2.9) and oilseed rape (8.9) productions. The transformities of the systems' products represented different energy efficiencies for rice (2.50E + 05 sej·J-1), wheat (1.66E + 05 sej·J-1) and oilseed rape (2.14E + 05 sej·J-1) production systems. According to several emergy indices, of the three systems evaluated, the rice system had the greatest level of sustainability. However, all of them were less sustainable than the ecological agricultural systems. A sensitivity analysis showed that the emergy inputs of irrigation water and nitrogenous fertilizer were the highest sensitivity factors influencing the emergy ratios. Best Management Practices, and other agroecological strategies, could be implemented to make further improvements in the sustainability of the three systems.

Design and Evaluation of a Prompting Instrument to Support Learning within the Diffusion Simulation Game

ERIC Educational Resources Information Center

Kwon, Seolim; Lara, Miguel; Enfield, Jake; Frick, Theodore

2013-01-01

Conducting an iterative usability testing, a set of prompts used as a form of instructional support was developed in order to facilitate the comprehension of the diffusion of innovations theory (Rogers, 2003) in a simulation game called the Diffusion Simulation Game (DSG) (Molenda & Rice, 1979). The six subjects who participated in the study…

Thermal decomposition of ethanol. 4. Ab initio chemical kinetics for reactions of H atoms with CH3CH2O and CH3CHOH radicals.

PubMed

Xu, Z F; Xu, Kun; Lin, M C

2011-04-21

The potential energy surfaces of H-atom reactions with CH(3)CH(2)O and CH(3)CHOH, two major radicals in the decomposition and oxidation of ethanol, have been studied at the CCSD(T)/6-311+G(3df,2p) level of theory with geometric optimization carried out at the BH&HLYP/6-311+G(3df,2p) level. The direct hydrogen abstraction channels and the indirect association/decomposition channels from the chemically activated ethanol molecule have been considered for both reactions. The rate constants for both reactions have been calculated at 100-3000 K and 10(-4) Torr to 10(3) atm Ar pressure by microcanonical VTST/RRKM theory with master equation solution for all accessible product channels. The results show that the major product channel of the CH(3)CH(2)O + H reaction is CH(3) + CH(2)OH under atmospheric pressure conditions. Only at high pressure and low temperature, the rate constant for CH(3)CH(2)OH formation by collisonal deactivation becomes dominant. For CH(3)CHOH + H, there are three major product channels; at high temperatures, CH(3)+CH(2)OH production predominates at low pressures (P < 100 Torr), while the formation of CH(3)CH(2)OH by collisional deactivation becomes competitive at high pressures and low temperatures (T < 500 K). At high temperatures, the direct hydrogen abstraction reaction producing CH(2)CHOH + H(2) becomes dominant. Rate constants for all accessible product channels in both systems have been predicted and tabulated for modeling applications. The predicted value for CH(3)CHOH + H at 295 K and 1 Torr pressure agrees closely with available experimental data. For practical modeling applications, the rate constants for the thermal unimolecular decomposition of ethanol giving key accessible products have been predicted; those for the two major product channels taking place by dehydration and C-C breaking agree closely with available literature data.

Regular Morphology and the Lexicon.

ERIC Educational Resources Information Center

Bybee, Joan

1995-01-01

This article compares three models of morphological storage and processing: (1) the dual-processing model of Pinker, Marcus and others; (2) the connectionist model of Marchman, Plunkett, Seidenberg, and others; and (3) the network model of Bybee and Langacker. Type frequency of a morphological pattern is shown to be important in determining…

Understanding the Charter School Special Education Gap: Evidence from Denver, Colorado

ERIC Educational Resources Information Center

Winters, Marcus A.

2014-01-01

Center on Reinventing Public Education (CRPE) commissioned Dr. Marcus Winters to analyze the factors driving the special education gap between Denver's charter and traditional public elementary and middle schools. Using student-level data, Winters shows that Denver's special education enrollment gap starts at roughly 2 percentage points in…

2005 Armaments Technology Seminar and Exhibition

DTIC Science & Technology

2005-06-13

Carolina Sofer •Catina Crismale •Preparedness •Jason Emmel •Andrea Marcus •James Smith •Tim Phelan •Nikiesha Nicholas •Kathy Wioland •Mary Paczkowski • Jamie ...ASSESS PRI CATEGORY HPTs EFFECTS AGENCY ASSET AGENCY ASSET WHEN AGENCY ASSET 1 3 4 5 6 LAWTON Mayor Coop

The Perils of Repressive Tolerance in Music Education Curriculum

ERIC Educational Resources Information Center

Perrine, William M.

2017-01-01

In recent years, philosophers of music education have called for a greater degree of political engagement by music education practitioners. Using Marcuse's discussion of "repressive tolerance" as a conceptual framework, I argue that a politicized curriculum in music education works against the liberal ideas of free speech and a free…

Anarchism, Schooling, and Democratic Sensibility

ERIC Educational Resources Information Center

Kennedy, David

2017-01-01

This paper seeks to address the question of schooling for democracy by, first, identifying at least one form of social character, dependent, after Marcuse, on the historical emergence of a "new sensibility." It then explores one pedagogical thread related to the emergence of this form of subjectivity over the course of the last two…

An Archetypal Phenomenology of "Skholé"

ERIC Educational Resources Information Center

Kennedy, David

2017-01-01

In this essay David Kennedy argues that children represent one vanguard of an emergent shift in Western subjectivity, and that adult-child dialogue, especially in the context of schooling, is a key locus for the epistemological change that implies. Following Herbert Marcuse's invocation of a "new sensibility," Kennedy argues that the…

Approval of Alternative Test Method for Puerto Nuevo Wastewater Treatment Plant, San Juan, Puerto Rico Memorandum

EPA Pesticide Factsheets

This December 2008 memorandum is from Conniesue Oldham of the Measurement Technology Group to Marcus E. Kantz in EPA Region 2. This memorandum is regarding a request to use an alternative test method at the Puerto Neuvo wastewater treatment plant

78 FR 49267 - Conflict of Interest Waiver

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-13

... FEDERAL COMMUNICATIONS COMMISSION Conflict of Interest Waiver AGENCY: Federal Communications Commission. ACTION: Notice of waiver of section 4(b) of the Communications Act of 1934. SUMMARY: Notice is... section 4(b) of the Communications Act of 1924, as amended, 47 U.S.C. 154(b), for Mr. Theodore Marcus...

22. Photocopy of architectural drawing. (Original is in the collection ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Photocopy of architectural drawing. (Original is in the collection of Richard F. McCann, Pasadena, CA.) Grandstand Balcony Plan. Dated June 30, 1933. Race Course for Mr. Joseph Gottstein, Washington Jockey Club. B. Marcus Priteca. - Longacres, Original Grandstand, 1621 Southwest Sixteenth Street, Renton, King County, WA

Learning Non-Adjacent Regularities at Age 0 ; 7

ERIC Educational Resources Information Center

Gervain, Judit; Werker, Janet F.

2013-01-01

One important mechanism suggested to underlie the acquisition of grammar is rule learning. Indeed, infants aged 0 ; 7 are able to learn rules based on simple identity relations (adjacent repetitions, ABB: "wo fe fe" and non-adjacent repetitions, ABA: "wo fe wo", respectively; Marcus et al., 1999). One unexplored issue is…

National CrossTalk. Volume 12, Number 3, Summer 2004

ERIC Educational Resources Information Center

Trombley, William, Ed.

2004-01-01

The primary purpose of "National CrossTalk" is to stimulate informed discussion and debate of higher education issues. This issue contains the following articles: (1) U.K. Adopts "Top-Up" Tuition Fees: British Universities Prepare to Compete in a More "American" System (Jon Marcus); (2) "Plain Living": Berea…

National CrossTalk. Volume 15, Number 1, Winter 2007

ERIC Educational Resources Information Center

Trombley, William, Ed.

2007-01-01

The primary purpose of "National CrossTalk" is to stimulate informed discussion and debate of higher education issues. This issue contains the following articles: (1) The Celtic Tiger: Ireland Invests Heavily in Higher Education, and Benefits Mightily (Jon Marcus); (2) Western Classic: Nevada's James Rogers Is a Non-Traditional…

National CrossTalk. Volume 17, Number 1

ERIC Educational Resources Information Center

Trombley, William, Ed.

2009-01-01

The primary purpose of "National CrossTalk" is to stimulate informed discussion and debate of higher education issues. This issue contains the following articles: (1) Florida's Unnatural Disaster: The State's Economic Bubble Has Burst, Leaving Higher Education in a Double Bind (Jon Marcus); (2) Saudi King's Modern University:…

lcmodels

Cancer.gov

The R package provides individual risks of lung cancer and lung cancer death based on various published papers: Bach et al., 2003; Spitz et al., 2007; Cassidy et al., 2008 (LLP); Hoggart et al., 2012; Tammemagi et al., 2013; Marcus et al., 2015 (LLPi); Wilson and Weissfeld, 2015 (Pittsburgh); Katki et al., 2016 (LCRAT and LCDRAT)

The NMC Horizon Report: 2013 Museum Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Freeman, A.

2013-01-01

The "NMC Horizon Report: 2013 Museum Edition," is a co-production with the Marcus Institute for Digital Education in the Arts (MIDEA), and examines six emerging technologies for their potential impact on and use in education and interpretation within the museum environment: BYOD (Bring Your Own Device), crowdsourcing, electronic…

Gifted Sixth-Graders and Primary Source Philosophy.

ERIC Educational Resources Information Center

White, David A.; Schlaggar, Sheila

1993-01-01

A sixth-grade gifted class studied the history of philosophy, including selections from such philosophers as Plato, Confucius, Buddha, Marcus Aurelius, and Moses Maimonides. Readings drew on fundamental features of child experience, such as their sense of justice, concern for moral values, and questions about reality. The paper describes classroom…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merkle, J.G.

In order to study effects of constraint on fracture toughness, it is important to select the right location within the crack-tip field for investigation. In 1950 Hill postulated that close to a circular notch tip the principal stress directions would be radial and circumferential, so that the plastic slip lines (maximum shear stress trajectories) would be logarithmic spirals. The resulting equation for stress normal to the notch symmetry plane, neglecting strain hardening, was identical to that for the circumferential stress near the bore of an ideally plastic thick-walled hollow cylinder under external radial tension, because the relevant geometries are identical.more » In 1969, Rice and Johnson developed a near crack-tip, plane strain, large-strain rigid-plastic analysis considering strain hardening and assuming an infinitely sharp initial crack tip. Shortly afterwards, Merkle, following Hill's suggestion, proposed an approximate analysis of the stresses and strains ahead of a blunted crack tip on the plane of symmetry, based on a circular blunted crack tip. The analysis amounted to a hollow cylinder analogy, including the effects of strain hardening. The original hollow cylinder analogy was based on small strain theory, and the calculated strain distributions did not agree well with the Rice and Johnson results very near the blunted crack tip. Therefore, the hollow cylinder analogy equations have been rederived, based on large strain theory, and the agreement with the Rice and Johnson results and other more recent numerical results is good. Calculations illustrate the effects of transverse strain on the principal stresses very close to a blunting crack tip and show that, theoretically, a singularity still exists at the tip of a blunting crack. 10 refs., 9 figs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arlt, T.; Penzkofer H.; Zinth, W.

The energetics of the primary electron donor (the special pair P) in reaction centers from Rhodopseudomonas viridis were modified by site-directed mutagenesis of histidine L168 to phenylalanine. This leads to the loss of a hydrogen bond between the amino acid side chain and the ring I acetyl carbonyl oxygen of the bacteriochlorophyll molecule BChl{sub LP}. As a result of the mutation, a 35 nm blue shift of the Q{sub y} band of the special pair and a decrease of 80 mV in the P/P{sup +} oxidation-reduction potential occur. Femtosecond spectroscopy revealed an acceleration of the first electron transfer step frommore » 3.5 ps in wild type to 1.1 ps in mutant. Analysis of change in the bacteriochlorophyll monomer (B) band of the mutant reaction centers showed strong bleaching. This is direct evidence that bacteriochlorophyll b is real intermediate in electron transfer. The changes in redox potential and time constants allow one to estimate the energetics in the wild-type and mutated reaction centers according to the Marcus electron transfer theory. 32 refs., 6 figs.« less

Non-conjugated, phenyl assisted coupling in through bond electron transfer in a perylenemonoimide-triphenylamine system.

PubMed

Bell, Toby D M; Stefan, Alina; Lemaur, Vincent; Bernhardt, Stefan; Müllen, Klaus; Cornil, Jérôme; Beljonne, David; Hofkens, Johan; Van der Auweraer, Mark; De Schryver, Frans C

2007-04-01

Two donor-bridge-acceptor compounds containing triphenylamine (TPA) donors and perylenemonoimide (PMI) acceptors have been studied by spectroscopic techniques and quantum chemical computation. Both systems have been observed to emit prompt and delayed fluorescence under certain conditions indicating that forward and reverse electron transfer (ET) processes can occur between the locally excited and the charge separated states. The experimental and computational results show that the TPA and PMI chromophores are better coupled by almost 50% in the meta isomers which undergo ET more readily than the para isomers. Quantum chemical calculations indicate that this unexpected situation is the result of a phenyl group on the side of the bridge being advantageously positioned in the meta isomers. This leads to more extensive delocalisation of the TPA HOMO into the bridge enhancing the total through bond electronic coupling between the TPA and PMI chromophores. The calculations also indicate a strong angle dependence of the total coupling in both isomers. The experimental results are discussed in the context of the high temperature limit of Marcus's theory of non-adiabatic ET.

Mechanistic information from the first volume profile analysis for a reversible intermolecular electron-transfer reaction involving pentaammine(isonicotinamide)ruthenium and cytochrome c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baensch, B.; Meier, M.; Martinez, P.

1994-10-12

The reversible intermolecular electron-transfer reaction between pentaammine(isonicotinamide)ruthenium(II/III) and horse-heart cytochrome c iron(III/II) was subjected to a detailed kinetic and thermodynamic study as a function of temperature and pressure. Theoretical calculations based on the Marcus-Hush theory were employed to predict all rate and equilibrium constants as well as activation parameters. There is an excellent agreement between the kinetically and thermodynamically determined equilibrium constants and associated pressure parameters. These data are used to construct a volume profile for the overall process, from which it follows that the transition state lies halfway between the reactant and product states on a volume basis. Themore » reorganization in the transition state has reached a similar degree in both directions of the electron-transfer process and corresponds to a {lambda}{sup {double_dagger}} value of 0.44 for this reversible reaction. This is the first complete volume profile analysis for a reversible intermolecular electron-transfer reaction.« less

Effect of the phenoxy groups on PDIB and its derivatives

NASA Astrophysics Data System (ADS)

Song, Peng; Guan, Baijie; Zhou, Qiao; Zhao, Meiyu; Huang, Jindou; Ma, Fengcai

2016-10-01

The anisotropic hole and electron mobilities in N,N‧-3,4,9,10-perylenediimide-1,7-phenoxy (PDIB-2OPh) and N,Nʹ-3,4,9,10-perylenediimide (PDIB) were theoretically predicted using the Marcus-Hush theory. The substituent effect of phenoxy on their mobility rates, absorption spectra, electron affinities, and ionization potentials was explored. By comparing the simulated hole mobility in PDIB and PDIB-2OPh, it is found that the phenoxy rings act as spacers between adjacent stacking columns in the phenoxy-substituted derivatives. The increasement of the number of benzene oxygen groups leads to the absorption spectra red-shift of these molecular systems. This coincides with their change tendency of the adiabatic ionization potentials, vertical ionization potentials. However, the calculated adiabatic electron affinities and vertical electron affinities of N,N‧-butyl-3,4,9,10-perylenediimide-1,6,7,12-phenoxy (PDIB-4OPh) are larger than those of PDIB;OPh. The steric effect in PDIB-4OPh is expected to cause space reversal and thus to changes in the properties of the molecule.

Mulliken Hush elucidation of the encounter (precursor) complex in intermolecular electron transfer via self-exchange of tetracyanoethylene anion-radical

NASA Astrophysics Data System (ADS)

Rosokha, S. V.; Newton, M. D.; Head-Gordon, M.; Kochi, J. K.

2006-05-01

The paramagnetic [1:1] encounter complex (TCNE)2-rad is established as the important precursor in the kinetics and mechanism of electron-transfer for the self-exchange between tetracyanoethylene acceptor ( TCNE) and its radical-anion as the donor. Spectroscopic observation of the dimeric complex (TCNE)2-rad by its intervalence absorption band at the solvent-dependent wavelength of λIV ˜ 1500 nm facilitates the application of Mulliken-Hush theory which reveals the significant electronic interaction extant between the pair of cofacial TCNE moieties with the sizable coupling of HDA = 1000 cm -1. The transient existence of such an encounter complex provides the critical link in the electron-transfer kinetics by lowering the classical Marcus reorganization barrier by the amount of HDA in this strongly adiabatic system. Ab initio quantum-mechanical methods as applied to independent theoretical computations of both the reorganization energy ( λ) and the electronic coupling element ( HDA) confirm the essential correctness of the Mulliken-Hush formalism for fast electron transfer via strongly coupled donor/acceptor encounter complexes.

Iron(IV)hydroxide pK(a) and the role of thiolate ligation in C-H bond activation by cytochrome P450.

PubMed

Yosca, Timothy H; Rittle, Jonathan; Krest, Courtney M; Onderko, Elizabeth L; Silakov, Alexey; Calixto, Julio C; Behan, Rachel K; Green, Michael T

2013-11-15

Cytochrome P450 enzymes activate oxygen at heme iron centers to oxidize relatively inert substrate carbon-hydrogen bonds. Cysteine thiolate coordination to iron is posited to increase the pK(a) (where K(a) is the acid dissociation constant) of compound II, an iron(IV)hydroxide complex, correspondingly lowering the one-electron reduction potential of compound I, the active catalytic intermediate, and decreasing the driving force for deleterious auto-oxidation of tyrosine and tryptophan residues in the enzyme's framework. Here, we report on the preparation of an iron(IV)hydroxide complex in a P450 enzyme (CYP158) in ≥90% yield. Using rapid mixing technologies in conjunction with Mössbauer, ultraviolet/visible, and x-ray absorption spectroscopies, we determine a pK(a) value for this compound of 11.9. Marcus theory analysis indicates that this elevated pK(a) results in a >10,000-fold reduction in the rate constant for oxidations of the protein framework, making these processes noncompetitive with substrate oxidation.

Electronic and structural aspects of p450-mediated drug metabolism.

PubMed

Lewis, David F V; Ito, Yuko; Lake, Brian G

2009-04-01

From a consideration of first principles for enzymes kinetics, we have employed theoretical methods which enable one to analyse the kinetics of cytochrome P450-mediated reactions which have been based on the known physicochemical principles underlying the majority of chemical or enzymatic reactions. A comparison is made between the correlation equations produced from the QSAR analysis of experimental P450 reaction rate data and those obtained from first principles, where there appears to be a generally satisfactory concordance between the two procedures. In this respect, we have developed expressions based on standard reaction kinetics theory which incorporate the Eyring and Marcus relationships. The analysis of P450-catalyzed reaction rates is elaborated to encompass a treatment of metabolic clearance, and satisfactory correlations are obtained with literature values for both intrinsic clearance and whole body clearance in terms of compound lipophilicity derived from log P data, where P is the octanol/water partition coefficient. The importance of ionization potential as a factor in the overall catalytic turnover of P450-mediated reactions is noted, especially in combination with the lipophilicity parameter, log P.

From computational discovery to experimental characterization of a high hole mobility organic crystal

PubMed Central

Sokolov, Anatoliy N.; Atahan-Evrenk, Sule; Mondal, Rajib; Akkerman, Hylke B.; Sánchez-Carrera, Roel S.; Granados-Focil, Sergio; Schrier, Joshua; Mannsfeld, Stefan C.B.; Zoombelt, Arjan P.; Bao, Zhenan; Aspuru-Guzik, Alán

2011-01-01

For organic semiconductors to find ubiquitous electronics applications, the development of new materials with high mobility and air stability is critical. Despite the versatility of carbon, exploratory chemical synthesis in the vast chemical space can be hindered by synthetic and characterization difficulties. Here we show that in silico screening of novel derivatives of the dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene semiconductor with high hole mobility and air stability can lead to the discovery of a new high-performance semiconductor. On the basis of estimates from the Marcus theory of charge transfer rates, we identified a novel compound expected to demonstrate a theoretic twofold improvement in mobility over the parent molecule. Synthetic and electrical characterization of the compound is reported with single-crystal field-effect transistors, showing a remarkable saturation and linear mobility of 12.3 and 16 cm2 V−1 s−1, respectively. This is one of the very few organic semiconductors with mobility greater than 10 cm2 V−1 s−1 reported to date. PMID:21847111

Characterization of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf2N])∕TX-100∕cyclohexane ternary microemulsion: investigation of photoinduced electron transfer in this RTIL containing microemulsion.

PubMed

Sarkar, Souravi; Pramanik, Rajib; Ghatak, Chiranjib; Rao, Vishal Govind; Sarkar, Nilmoni

2011-02-21

In this study we have characterized a ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl- sulfonyl)imide containing ternary nonaqueous microemulsion ([Emim][Tf(2)N]∕∕TX-100∕cyclo- hexane). The phase behavior and dynamic light scattering study show that the [Emim][Tf(2)N]∕TX-100∕cyclohexane three component system can form microemulsion with [Emim][Tf(2)N] as polar core at suitable condition. We have investigated photoinduced electron transfer (PET) using dimethyl aniline as electron donor and several Coumarin dyes as electron acceptor molecules at two different R values (R = [ionic liquid]∕[surfactant]) to observe how the dynamics of the PET rate is affected in this type of confined microenvironment compared to that of the PET dynamics in neat ionic liquid and other pure solvent media. The plot of observed k(q) values with the free energy change (ΔG(0)) for electron transfer reaction shows an apparent inversion in the observed rate as predicted by the Marcus theory.

Bottom-up view of water network-mediated CO2 reduction using cryogenic cluster ion spectroscopy and direct dynamics simulations.

PubMed

Breen, Kristin J; DeBlase, Andrew F; Guasco, Timothy L; Voora, Vamsee K; Jordan, Kenneth D; Nagata, Takashi; Johnson, Mark A

2012-01-26

The transition states of a chemical reaction in solution are generally accessed through exchange of thermal energy between the solvent and the reactants. As such, an ensemble of reacting systems approaches the transition state configuration of reactant and surrounding solvent in an incoherent manner that does not lend itself to direct experimental observation. Here we describe how gas-phase cluster chemistry can provide a detailed picture of the microscopic mechanics at play when a network of six water molecules mediates the trapping of a highly reactive "hydrated electron" onto a neutral CO(2) molecule to form a radical anion. The exothermic reaction is triggered from a metastable intermediate by selective excitation of either the reactant CO(2) or the water network, which is evidenced by the evaporative decomposition of the product cluster. Ab initio molecular dynamics simulations of energized CO(2)·(H(2)O)(6)(-) clusters are used to elucidate the nature of the network deformations that mediate intracluster electron capture, thus revealing the detailed solvent fluctuations implicit in the Marcus theory for electron-transfer kinetics in solution.

Niche construction on Bali: the gods of the countryside

PubMed Central

Lansing, J. Stephen; Fox, Karyn M.

2011-01-01

Human niche construction encompasses both purely biological phenomena, such as the evolution of lactose tolerance, and dual inheritance theory, which investigates the transmission of cultural information. But does niche construction help to explain phenomena in which conscious intention also plays a role? The creation of the engineered landscape of Balinese rice terraces offers a test case. Population genetic analysis and archaeological evidence are used to investigate whether this phenomenon emerged historically from trial and error by generations of farmers, or alternatively was designed by Bali's rulers. In light of strong support for the former hypothesis, two models are developed to explore the emergence of functional structure at both local and global scales. As time goes forward and selected patterns of irrigation schedules are implemented, local variation in rice harvests influences future decisions by the farmers, creating a coupled human–natural system governed by feedback from the environment. This mathematical analysis received a measure of empirical support when government agricultural policies severed the local feedback channels, resulting in the almost instantaneous collapse of rice harvests. The historical process of niche construction may also have included an evolution of religious consciousness, reflected in the beliefs and practices of the water temple cult. PMID:21320905

An approximate classical unimolecular reaction rate theory

NASA Astrophysics Data System (ADS)

Zhao, Meishan; Rice, Stuart A.

1992-05-01

We describe a classical theory of unimolecular reaction rate which is derived from the analysis of Davis and Gray by use of simplifying approximations. These approximations concern the calculation of the locations of, and the fluxes of phase points across, the bottlenecks to fragmentation and to intramolecular energy transfer. The bottleneck to fragment separation is represented as a vibration-rotation state dependent separatrix, which approximation is similar to but extends and improves the approximations for the separatrix introduced by Gray, Rice, and Davis and by Zhao and Rice. The novel feature in our analysis is the representation of the bottlenecks to intramolecular energy transfer as dividing surfaces in phase space; the locations of these dividing surfaces are determined by the same conditions as locate the remnants of robust tori with frequency ratios related to the golden mean (in a two degree of freedom system these are the cantori). The flux of phase points across each dividing surface is calculated with an analytic representation instead of a stroboscopic mapping. The rate of unimolecular reaction is identified with the net rate at which phase points escape from the region of quasiperiodic bounded motion to the region of free fragment motion by consecutively crossing the dividing surfaces for intramolecular energy exchange and the separatrix. This new theory generates predictions of the rates of predissociation of the van der Waals molecules HeI2, NeI2 and ArI2 which are in very good agreement with available experimental data.

[Medicine behind bars. Illness is usual not grounds for modifying imprisonment].

PubMed

Schwarzkopf, A; Zenker, M

2002-05-16

The article describes the possibilities of medical care in prison as exemplified by the Kassel 1 prison with its attached central hospital facility. The main areas of medical care covered there are the treatment of wounds, conservative treatment of fractures, ophthalmology, ENT, urology, dentistry and, via external consultant physicians, also internal medicine, pneumology, dermatology and gynecology. Such infections as hepatitis B and C, syphilis, and tuberculosis have a greater prevalence among prisoners--in contrast to other infections afflicting people housed under similar living conditions, such as in communal living facilities, which show no such increased prevalence. Furthermore, there is a relatively high percentage of injuries, including those that are self-inflicted. The problem of certifying a prisoner medically unfit to tolerate imprisonment is discussed.

Disrupting Myths of Poverty in the Face of Resistance

ERIC Educational Resources Information Center

Pollock, Katina; Lopez, Ann; Joshee, Reva

2013-01-01

This case disrupts some of the prevalent myths about families from low-income and poor households held by educators. Recognizing the inherent tensions, this case demonstrates the importance of creating equitable and inclusive learning environments. We presented some of the challenges faced by Marcus, a progressive principal, as he attempts to…

Re-Imagining Spaces, Collectivity, and the Political Dimension of Contemporary Art

ERIC Educational Resources Information Center

Peters, Clorinde

2015-01-01

In a neoliberal moment of cultural production marked by commodification and the dominance of economic values, it is necessary to investigate the cultural, social, and aesthetic value of art. By examining Herbert Marcuse's aesthetic dimension, this article seeks to locate the political and pedagogic potential both in the aesthetics and in the…

Evaluating Teaching in Higher Education. A Collection of Conference Papers.

ERIC Educational Resources Information Center

London Univ. (England). Inst. of Education.

Some of the difficult problems related to introducing greater accountability for teaching were assessed and tentative policies considered at a British conference on higher education held in April 1975. R.C. Tress, Peter Kennedy, R. Rickett, Tom Driver, Marcus Merriman, and Alastair Stewart are the authors of the first set of papers entitled…

Molecular Dynamics Simulations of the Hydrogen Peroxyl Radical

DTIC Science & Technology

2014-05-01

Pasta , and Ulam10 (FPU) on the equipartion of energy in a one-dimensional anharmonic chain of oscillators yielded results that surprised the...Slater, Proc. Camb. Phil. Soc. 35, 56 (1939). 9 R. A. Marcus, J. Chem. Phys. 20, 359 (1952). 10 E. Fermi, J. R. Pasta , and S. M. Ulam, Los Alamos

The Voice of Authority

ERIC Educational Resources Information Center

Wetterlund, Kris

2012-01-01

In the last part of 2011, conversations swirled around the Internet and print about the assault on museum authority. The Marcus Institute for Digital Education in the Arts (MIDEA) summarized some of the discussion in their blog entry "The Participatory Museum and a New Authority." Other sites joined in the discussion, for example, the Museum Geek…

20 CFR Appendix A to Subpart F of... - U.S. Seaports

Code of Federal Regulations, 2010 CFR

2010-04-01

... Port, LA New Orleans, LA Beaumont, TX Brownsville, TX Corpus Christi, TX Freeport, TX Galveston, TX..., MA Fall River, MA New Bedford, MA Providence, RI Bridgeport, CT New Haven, CT New London, CT Albany, NY New York, NY/NJ Camden, NJ Gloucester City, NJ Paulsboro, NJ Chester, PA Marcus Hook, PA...

Factors Associated with Transitional Shifts in College Students' Physical Activity Behavior

ERIC Educational Resources Information Center

Levy, Susan S.; Cardinal, Bradley J.

2006-01-01

The Transtheoretical Model (Prochaska & Marcus, 1994) has been widely used as a framework for understanding exercise behavior change. The purpose of this study was to clarify equivocal research findings reported for model predictions when examining stage movement over time rather than static stages and to provide some evidence of the construct…

National CrossTalk. Volume 14, Number 3, Summer 2006

ERIC Educational Resources Information Center

Trombley, William, Ed.

2006-01-01

The primary purpose of "National CrossTalk" is to stimulate informed discussion and debate of higher education issues. This issue contains the following articles: (1) The M Word: "Marketing" Has Changed from a Dirty Word to a Buzzword in Higher Education (Jon Marcus); (2) A Contrarian View of the Testing Industry: FairTest…

Return on Investment in the Public Sector

DTIC Science & Technology

2004-12-01

of Corporate Finance . 4th Ed. New York: McGraw-Hill/Irwin, 2004. Brook, Douglas A. <dabrook@nps.navy.mil> “CNO Visit.” [E-mail to Larry Jones...Analysis: Concepts and Practice. 10th Ed. Upper Saddle River: Prentice Hall, 1996. Brealey, Richard, Alan J. Marcus, and Stewart C. Myers. Fundamentals

Charge transfer in model peptides: obtaining Marcus parameters from molecular simulation.

PubMed

Heck, Alexander; Woiczikowski, P Benjamin; Kubař, Tomáš; Giese, Bernd; Elstner, Marcus; Steinbrecher, Thomas B

2012-02-23

Charge transfer within and between biomolecules remains a highly active field of biophysics. Due to the complexities of real systems, model compounds are a useful alternative to study the mechanistic fundamentals of charge transfer. In recent years, such model experiments have been underpinned by molecular simulation methods as well. In this work, we study electron hole transfer in helical model peptides by means of molecular dynamics simulations. A theoretical framework to extract Marcus parameters of charge transfer from simulations is presented. We find that the peptides form stable helical structures with sequence dependent small deviations from ideal PPII helices. We identify direct exposure of charged side chains to solvent as a cause of high reorganization energies, significantly larger than typical for electron transfer in proteins. This, together with small direct couplings, makes long-range superexchange electron transport in this system very slow. In good agreement with experiment, direct transfer between the terminal amino acid side chains can be dicounted in favor of a two-step hopping process if appropriate bridging groups exist. © 2012 American Chemical Society

Equilibrium fluctuation relations for voltage coupling in membrane proteins.

PubMed

Kim, Ilsoo; Warshel, Arieh

2015-11-01

A general theoretical framework is developed to account for the effects of an external potential on the energetics of membrane proteins. The framework is based on the free energy relation between two (forward/backward) probability densities, which was recently generalized to non-equilibrium processes, culminating in the work-fluctuation theorem. Starting from the probability densities of the conformational states along the "voltage coupling" reaction coordinate, we investigate several interconnected free energy relations between these two conformational states, considering voltage activation of ion channels. The free energy difference between the two conformational states at zero (depolarization) membrane potential (i.e., known as the chemical component of free energy change in ion channels) is shown to be equivalent to the free energy difference between the two "equilibrium" (resting and activated) conformational states along the one-dimensional voltage couplin reaction coordinate. Furthermore, the requirement that the application of linear response approximation to the free energy functionals of voltage coupling should satisfy the general free energy relations, yields a novel closed-form expression for the gating charge in terms of other basic properties of ion channels. This connection is familiar in statistical mechanics, known as the equilibrium fluctuation-response relation. The theory is illustrated by considering the coupling of a unit charge to the external voltage in the two sites near the surface of membrane, representing the activated and resting states. This is done using a coarse-graining (CG) model of membrane proteins, which includes the membrane, the electrolytes and the electrodes. The CG model yields Marcus-type voltage dependent free energy parabolas for the response of the electrostatic environment (electrolytes etc.) to the transition from the initial to the final configuratinal states, leading to equilibrium free energy difference and free energy barrier that follow the trend of the equilibrium fluctuation relation and the Marcus theory of electron transfer. These energetics also allow for a direct estimation of the voltage dependence of channel activation (Q-V curve), offering a quantitative rationale for a correlation between the voltage dependence parabolas and the Q-V curve, upon site-directed mutagenesis or drug binding. Taken together, by introducing the voltage coupling as the energy gap reaction coordinate, our framework brings new perspectives to the thermodynamic models of voltage activation in voltage-sensitive membrane proteins, offering an a framework for a better understating of the structure-function correlations of voltage gating in ion channels as well as electrogenic phenomena in ion pumps and transporters. Significantly, this formulation also provides a powerful bridge between the CG model of voltage coupling and the conventional macroscopic treatments. Copyright © 2015 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howell, Matthew D.; McLellan, Jason G.

This report summarizes catch data collected from white sturgeon Acipenser transmontanus in Lake Roosevelt during limited setlining and gill netting activities in the fall of 2003, and documents progress toward development of a U.S. white sturgeon conservation aquaculture program for Lake Roosevelt. From 27-30 October, 42 overnight small mesh gill net sets were made between Marcus and Northport, WA for a total catch of 15 juvenile white sturgeon (275-488 mm FL). All sturgeon captured were of Canadian hatchery origin. These fish had been previously released as sub-yearlings into the Canadian portion (Keenleyside Reach) of the Transboundary Reach of the Columbiamore » River during 2002 and 2003. Most sturgeon (n=14) were caught in the most upstream area sampled (Northport) in low velocity eddy areas. Five fish exhibited pectoral fin deformities (curled or stunted). Growth rates were less than for juvenile sturgeon captured in the Keenleyside Reach but condition factor was similar. Condition factor was also similar to that observed in juvenile sturgeon (ages 1-8) captured in the unimpounded Columbia River below Bonneville Dam between 1987-92. From 10-14 November, 28 overnight setline sets were made in the Roosevelt Reach between the confluence of the Spokane River and Marcus Island for a total catch of 17 white sturgeon (94-213 cm FL). Catch was greatest in the most upstream areas sampled, a distribution similar to that observed during a WDFW setline survey in Lake Roosevelt in 1998. The mean W{sub r} index of 110% for fish captured this year was higher than the mean W{sub r} of 91% for fish captured in 1998. Excellent fish condition hindered surgical examination of gonads as lipid deposits made the ventral body wall very thick and difficult to penetrate with available otoscope specula. Acoustic tags (Vemco model V16 coded pingers, 69 kHz, 48-month life expectancy) were internally applied to 15 fish for subsequent telemetry investigations of seasonal and reproductively motivated movements. In August 2003, three Vemco VR2 fixed station acoustic receivers, supplied by the UCWSRI Transboundary Telemetry Project, were deployed in the vicinities of Kettle Falls Bridge, Marcus Island, and Northport, WA. Data downloaded from these receivers through December 2003 confirmed the findings of a previous telemetry study that the Marcus area is an important overwintering habitat for white sturgeon. On 18 February 2004, juvenile white sturgeon (n=2,000) were transported from Kootenay Sturgeon Hatchery in British Columbia to WDFW Columbia Basin Hatchery (CBH) in Moses Lake, WA. Fish were reared at CBH to approximately 30 g and individually outfitted with PIT tags and scute marked. On 11 May 2004, fish were released into Lake Roosevelt in the vicinities of Kettle Falls Bridge, North Gorge, and Northport.« less

Investigating Reasons for CPAP Adherence in Adolescents: A Qualitative Approach

PubMed Central

Prashad, Priya S.; Marcus, Carole L.; Maggs, Jill; Stettler, Nicolas; Cornaglia, Mary A.; Costa, Priscilla; Puzino, Kristina; Xanthopoulos, Melissa; Bradford, Ruth; Barg, Frances K.

2013-01-01

Study Objectives: Adolescents with obstructive sleep apnea syndrome (OSAS) represent an important but understudied subgroup of long-term continuous positive airway pressure (CPAP) users. The purpose of this qualitative study was to identify factors related to adherence from the perspective of adolescents and their caregivers. Methods: Individual open-ended, semi-structured interviews were conducted with adolescents (n = 21) and caregivers (n = 20). Objective adherence data from the adolescents' CPAP machines during the previous month was obtained. Adolescents with different adherence levels and their caregivers were asked their views on CPAP. Using a modified grounded theory approach, we identified themes and developed theories that explained the adolescents' adherence patterns. Results: Adolescent participants (n = 21) were aged 12-18 years, predominantly male (n = 15), African American (n = 16), users of CPAP for at least one month. Caregivers were mainly mothers (n = 17). Seven adolescents had high use (mean use 381 ± 80 min per night), 7 had low use (mean use 30 ± 24 min per night), and 7 had no use during the month prior to being interviewed. Degree of structure in the home, social reactions, mode of communication among family members, and perception of benefits were issues that played a role in CPAP adherence. Conclusions: Understanding the adolescent and family experience of using CPAP may be key to increasing adolescent CPAP adherence. As a result of our findings, we speculate that health education, peer support groups, and developmentally appropriate individualized support strategies may be important in promoting adherence. Future studies should examine these theories of CPAP adherence. Citation: Prashad PS; Marcus CL; Maggs J; Stettler N; Cornaglia MA; Costa P; Puzino K; Xanthopoulos M; Bradford R; Barg FK. Investigating reasons for CPAP adherence in adolescents: a qualitative approach. J Clin Sleep Med 2013;9(12):1303-1313. PMID:24340293

Adventures on the C 3H 5O potential energy surface: OH+propyne, OH+allene and related reactions

DOE PAGES

Zádor, Judit; Miller, James A.

2014-06-25

We mapped out the stationary points and the corresponding conformational space on the C 3H 5O potential energy surface relevant for the OH + allene and OH + propyne reactions systematically and automatically using the KinBot software at the UCCSD(T)-F12b/cc-pVQZ-F12//M06-2X/6-311++G(d,p) level of theory. We used RRKM-based 1-D master equations to calculate pressure- and temperature-dependent, channel-specific phenomenological rate coefficients for the bimolecular reactions propyne + OH and allene + OH, and for the unimolecular decomposition of the CH 3CCHOH, CH 3C(OH)CH, CH 2CCH 2OH, CH 2C(OH)CH 2 primary adducts, and also for the related acetonyl, propionyl, 2-methylvinoxy, and 3-oxo-1-propyl radicals. Themore » major channel of the bimolecular reactions at high temperatures is the formation propargyl + H 2O, which makes the title reactions important players in soot formation at high temperatures. However, below ~1000 K the chemistry is more complex, involving the competition of stabilization, isomerization and dissociation processes. We found that the OH addition to the central carbon of allene has a particularly interesting and complex pressure dependence, caused by the low-lying exit channel to form ketene + CH 3 bimolecular products. In this study, we compared our results to a wide range of experimental data and assessed possible uncertainties arising from certain aspects of the theoretical framework.« less

Non-Rayleigh Sea Clutter: Properties and Detection of Targets

DTIC Science & Technology

1976-06-25

subject should consult Guinard and Daley [7], which provides an overview of the theory and references all the I______.... important work. 6 * .-- - - S...results for scattering from slightly rough surfaces and composite surfaces obtained by Rice [1], Wright [2,3], Valenzuela [4-6], Guinard and Daley [7], and...for vertical polarization. In 1970, Trunk and George [10] considered the log-normal and contaminated-normal descriptions of sea clutter and calculated

Methods for Scaling to Doubly Stochastic Form,

DTIC Science & Technology

1981-06-26

Frobenius -Konig Theorem (MARCUS and MINC [1964],p 97) A nonnegative n xn matrix without support contains an s x t zero subma- trix where: s +t =n + -3...that YA(k) has row sums 1. Then normalize the columns by a diagonal similarity transform defined as follows: Let x = (zx , • z,,) be a left Perron vector

Fostering Persistence: 3D Printing and the Unforeseen Impact on Equity

ERIC Educational Resources Information Center

FitzPatrick, Daniel L.; Dominguez, Victoria S.

2017-01-01

Teaching persistence and problem solving must begin with selecting a problem that can be solved mathematically, that allows for multiple methods of solving, and that generally captures the attention and curiosity of the student (Marcus and Fey 2003; NCTM 1991; Van de Walle 2003). This article shows how a STEM three-dimensional (3D) printing…

Joint Services Electronics Program (Harvard University. Cambridge, Massachusetts)

DTIC Science & Technology

1988-09-30

34Band Structures of Semimagnetic Compounds," Acta Physica Polonica bf A73 (6), 933-941 (1988). (Partially supported by N00014-86-K-0760). c. Books...Journals K.L. Babcock and R.M. Westervelt, "Dynamics of Simple Electronic neural Net- works," Physica 28D, 305 (1987). C.M. Marcus and R.M. Westervelt

Naive Probability: Model-based Estimates of Unique Events

DTIC Science & Technology

2014-05-04

Gilio & Over, 2012) – a possibility to which we return later. Despite these studies...Barrouillet, Jean-François Bonnefon, Nick Cassimatis, Nick Chater, Ernest Davis, Igor Douven, Angelo Gilio , Adam Harris, Gernot Kleiter, Gary Marcus, Ray...1230-1239. Gilio , A., & Over, D. (2012). The psychology of inferring conditionals from disjunctions: A probabilistic study. Journal of

The Rapid Detection of Single Bacterial Cells by Deep UV Micro Raman Spectroscopy.

DTIC Science & Technology

1992-04-01

Saltzman and C.T. Gregg, Appl. Environ. Microbiol. 44, 1081 (1982). 14. D.’. Mc Greggor, W.K. Grace and G.C. Salzman, in "Rapid Methods and...was used by Dr. Marcus Peter of the Dana -Farber Cancer Institute. During that period he came to our laboratories weekly to study GTP- binding

"Spreading the Love" and Using Performances to Prevent Rape

ERIC Educational Resources Information Center

Murphy, Aurora

2013-01-01

While rape is ordinarily considered an invariable reality, Sharon Marcus argues that it is instead a cultural script, which casts women as victims and men as perpetrators. In imagining rape as a script, it may seem pertinent to suggest that the arts and performance have a role in its prevention. Performances can provide a forum to publicly reflect…

76 FR 26255 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-06

..., the R/V Marcus G. Langseth (Langseth) and a seismic airgun array to collect seismic reflection and... possible, depending on logistics and weather. The proposed seismic survey will collect seismic reflection... Shillington, Spahr Webb, and Mladen Nedimovic, all of L-DEO. The vessel will be self-contained, and the crew...

The Oxidation of Ascorbic Acid by Hexacyanoferrate(III) Ion in Acidic Aqueous Media.

ERIC Educational Resources Information Center

Martins, Luis J. A.; da Costa, J. Barbosa

1988-01-01

Describes a kinetic and mechanistic investigation of ascorbic acid by a substitution-inert complex in acidic medium suitable for the undergraduate level. Discusses obtaining the second order rate constant for the rate determining step at a given temperature and comparison with the value predicted on the basis of the Marcus cross-relation. (CW)

7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

Code of Federal Regulations, 2010 CFR

2010-01-01

... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice...

7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

Code of Federal Regulations, 2011 CFR

2011-01-01

... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice...

Exploring the Potential of TanDEM-X Data in Rice Monitoring

NASA Astrophysics Data System (ADS)

Erten, E.

2015-12-01

In this work, phenological parameters such as growth stage, calendar estimation, crop density and yield estimation for rice fields are estimated employing TanDEM-X data. Currently, crop monitoring is country-dependent. Most countries have databases based on cadastral information and annual farmer inputs. Inaccuracies are coming from wrong or missing farmer declarations and/or coarsely updated cadastral boundary definitions. This leads to inefficient regulation of the market, frauds as well as to ecological risks. An accurate crop calendar is also missing, since farmers provide estimations in advance and there is no efficient way to know the growth status over large plantations. SAR data is of particular interest for these purposes. The proposed method includes two step approach including field detection and phenological state estimation. In the context of precise farming it is substantial to define field borders which are usually changing every cultivation period. Linking the SAR inherit properties to transplanting practice such as irrigation, the spatial database of rice-planted agricultural crops can be updated. Boundaries of agricultural fields will be defined in the database, and assignments of crops and sowing dates will be continuously updated by our monitoring system considering that sowing practice variously changes depending on the field owner decision. To define and segment rice crops, the system will make use of the fact that rice fields are characterized as flooded parcels separated by path networks composed by soil or rare grass. This natural segmentation is well detectable by inspecting low amplitude and coherence values of bistatic acquisitions. Once the field borders are defined, the phenology estimation of crops monitored at any time is the key point of monitoring. In this aspect the wavelength and the polarization option of TanDEM-X are enough to characterize the small phenological changes. The combination of bistatic interferometry and Radiative Transfer Theory (RTT) with different polarization provides a realistic description of plants including their full morphology (stalks, tillers, leaves and panicles).

Linking the historical and chemical definitions of diabatic states for charge and excitation energy transfer reactions in condensed phase.

PubMed

Pavanello, Michele; Neugebauer, Johannes

2011-10-07

Marcus theory of electron transfer (ET) and Förster theory of excitation energy transfer (EET) rely on the Condon approximation and the theoretical availability of initial and final states of ET and EET reactions, often called diabatic states. Recently [Subotnik et al., J. Chem. Phys. 130, 234102 (2009)], diabatic states for practical calculations of ET and EET reactions were defined in terms of their interactions with the surrounding environment. However, from a purely theoretical standpoint, the definition of diabatic states must arise from the minimization of the dynamic couplings between the trial diabatic states. In this work, we show that if the Condon approximation is valid, then a minimization of the derived dynamic couplings leads to corresponding diabatic states for ET reactions taking place in solution by diagonalization of the dipole moment matrix, which is equivalent to a Boys localization algorithm; while for EET reactions in solution, diabatic states are found through the Edmiston-Ruedenberg localization algorithm. In the derivation, we find interesting expressions for the environmental contribution to the dynamic coupling of the adiabatic states in condensed-phase processes. In one of the cases considered, we find that such a contribution is trivially evaluable as a scalar product of the transition dipole moment with a quantity directly derivable from the geometry arrangement of the nuclei in the molecular environment. Possibly, this has applications in the evaluation of dynamic couplings for large scale simulations. © 2011 American Institute of Physics

Theoretical insights into the effect of a conjugated core on the hole transport properties of hole-transporting materials for perovskite solar cells.

PubMed

Zhang, Zemin; Hu, Weixia; Cui, Jianyu; He, Rongxing; Shen, Wei; Li, Ming

2017-09-20

Conjugated bifluorenylidene and naphthalene central cores are introduced into hole-transporting materials DT1 and DT2 to replace the spiro-core of the reported, highly efficient FDT. The effects of the conjugated core on the geometrics, electronic properties and hole transport properties are investigated by using density functional theory coupled with Marcus theory and the Einstein relation. The calculated results show that DT1 (-5.21 eV) and DT2 (-5.23 eV) have lower HOMO levels than FDT (-5.15 eV), which indicates that the perovskite solar cells with conjugated hole-transporting materials can have higher open-circuit voltages. The introduction of the conjugated core is beneficial to the more efficient face-to-face packing pattern of the dimer, resulting in a larger intermolecular electronic coupling. Importantly, it is found that DT1 (1.6 × 10 -3 cm 2 V -1 s -1 ) and DT2 (2.7 × 10 -2 cm 2 V -1 s -1 ) exhibit relatively higher hole mobilities than FDT (1.3 × 10 -4 cm 2 V -1 s -1 ) owing to the larger electronic coupling. Therefore, enhanced hole transport ability can be achieved by switching from the spiro-core to the conjugated core. The present work provides a new strategy to improve the hole transport properties of hole-transporting materials, which will contribute to the development of conjugated small molecules as hole-transporting materials in efficient perovskite solar cells.

Fused thiophene and its periphery fluorinated substitution derivatives: a theoretical study for organic semiconductors

NASA Astrophysics Data System (ADS)

Wei, Hui-Ling; Shi, Ya-Rui; Liu, Yu-Fang

2015-06-01

A series of phenyl end-capped derivatives of benzo[d,d‧]thieno[3,2-b4,5- b‧]dithiophene (BTDT) with periphery-fluorinated substitutions (PFS) were systematically investigated by using density functional theory (DFT) combined with the Marcus-Hush electron transfer theory. The substituting effects of PFS were discussed. Compared with the original compounds, (i) the PFS compounds have a relatively higher efficiency of charge transport, lower barriers of electron injection, and larger HOMO-LUMO gaps; (ii) the air-stability and the device performance are enhanced by PFS; and (iii) the HOMO-LUMO transitions in the absorption spectrum of the PFS compounds show an obvious blue-shift trend. The perfluorophenylbisbenzo[d, d‧]thieno[3,2-b4,5-b‧]dithiophene (BpF-BTDT) is found to be the most stable and most effective compound in charge transport among the investigated compounds, and it is suggested as an ambipolar semiconducting material. The results of electronic coupling of the bisbenzo[d, d‧]thieno[3,2-b 4,5- b‧]dithiophene (BBTDT) derivatives show that the orbital interaction is mainly contributed by the neighboring molecule in the two dimensional (2D) layer. The PFS compounds have lower oxidization potential, ionization potential, and electron affinity values than the corresponding original ones, which suggest that fluorination can enhance the performance of the thiophene-based organic solar cells. These findings provide a better understanding of the PFS effects on organic semiconductors and may help to design high-performance semiconductor materials.

Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

DOE PAGES

Salter-Blanc, Alexandra; Bylaska, Eric J.; Johnston, Hayley; ...

2015-02-11

The evaluation of new energetic nitroaromatic compounds (NACs) for use in green munitions formulations requires models that can predict their environmental fate. The susceptibility of energetic NACs to nitro reduction might be predicted from correlations between rate constants (k) for this reaction and one-electron reduction potentials (E1NAC) / 0.059 V, but the mechanistic implications of such correlations are inconsistent with evidence from other methods. To address this inconsistency, we have reevaluated existing kinetic data using a (non-linear) free-energy relationship (FER) based on the Marcus theory of outer-sphere electron transfer. For most reductants, the results are inconsistent with rate limitation bymore » an initial, outer-sphere electron transfer, suggesting that the strong correlation between k and E1NAC is justified only as an empirical model. This empirical correlation was used to calibrate a new quantitative structure-activity relationship (QSAR) using previously reported values of k for non-energetic NAC reduction by Fe(II) porphyrin and newly reported values of E1NAC determined using density functional theory at the B3LYP/6-311++G(2d,2p) level with the COSMO solvation model. The QSAR was then validated for energetic NACs using newly measured kinetic data for 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,4-dinitroanisole (DNAN). The data show close agreement with the QSAR, supporting its applicability to energetic NACs.« less

Size and Temperature Dependence of Electron Transfer between CdSe Quantum Dots and a TiO 2 Nanobelt

DOE PAGES

Tafen, De Nyago; Prezhdo, Oleg V.

2015-02-24

Understanding charge transfer reactions between quantum dots (QD) and metal oxides is fundamental for improving photocatalytic, photovoltaic and electronic devices. The complexity of these processes makes it difficult to find an optimum QD size with rapid charge injection and low recombination. We combine time-domain density functional theory with nonadiabatic molecular dynamics to investigate the size and temperature dependence of the experimentally studied electron transfer and charge recombination at CdSe QD-TiO 2 nanobelt (NB) interfaces. The electron injection rate shows strong dependence on the QD size, increasing for small QDs. The rate exhibits Arrhenius temperature dependence, with the activation energy ofmore » the order of millielectronvolts. The charge recombination process occurs due to coupling of the electronic subsystem to vibrational modes of the TiO 2 NB. Inelastic electron-phonon scattering happens on a picosecond time scale, with strong dependence on the QD size. Our simulations demonstrate that the electron-hole recombination rate decreases significantly as the QD size increases, in excellent agreement with experiments. The temperature dependence of the charge recombination rates can be successfully modeled within the framework of the Marcus theory through optimization of the electronic coupling and the reorganization energy. Our simulations indicate that by varying the QD size, one can modulate the photoinduced charge separation and charge recombination, fundamental aspects of the design principles for high efficiency devices.« less

A quiet harvest: linkage between ritual, seed selection and the historical use of the finger-bladed knife as a traditional plant breeding tool in Ifugao, Philippines.

PubMed

Murphy, Kevin M

2017-01-13

The transverse harvest knife, also commonly called the finger or finger-bladed knife, has been utilized by rice farmers in southeast Asia for many centuries. The finger knife persisted in many traditional cultures long after the introduction of the sickle, a tool which provided farmers with the means to execute a much faster harvest. Several theories in interpretative archaeology have attempted to account for this rejection of more modern technological innovations. These theories, which include community-based social organization ideas and practical reasons for the continued use of the finger knife, are presented in this paper. Here I suggest an alternate theory based on a re-interpretation of existing research and fusion of existing theories: the primary reason for the historical and continued use of the finger knife is for seed selection through a centuries old tradition of plant breeding. Though I accept the accuracy of the practical and community-based, socio-cultural reasons for the use of the finger knife put forth by other authors, I suggest that seed selection and genetic improvement was the driving factor in the use of the finger knife. Indeed, intricate planting and harvesting rituals, which both ensured and encouraged varietal conservation and improvement co-evolved with the use of the finger knife as the primary harvest tool due to its unique ability to aid the farmer in the art and science of seed selection. When combined with previous ideas, this interpretative theory, based on the connection between ethnoagronomy and material culture, may provide a more complete picture of the story around the persistence of the finger knife in traditional rice-growing cultures in southeast Asia. I focus my theory on the terrace-building Ifugao people in the mountainous Cordillera region of northcentral Philippines; however, to put the use of the finger into a wider regional context, I draw from examples of the use of the finger knife in other traditional cultures throughout the region of southeast Asia.

Impact of diverse cultivars on molecular and crystalline structures of rice starch for food processing.

PubMed

Lee, Seul; Lee, Ju Hun; Chung, Hyun-Jung

2017-08-01

The objective of this study was to determine the molecular and crystalline structures of starches from diverse rice cultivars for three major food processing in Korea (cooked rice, brewing and rice cake). Rice starches were isolated from 10 different rice varieties grown in Korea. Apparent amylose contents of rice starches from cooked rice, brewing and rice cake varieties were 21.1-22.4%, 22.9-24.6%, and 20.1-22.0%, respectively. Rice starches from rice cake varieties showed higher peak viscosity but lower pasting temperature than those from cooked rice and brewing varieties. Swelling factor at 80°C of rice starches from cooked rice, brewing and rice cake varieties was 16.6-19.0, 17.8-19.3, and 17.8-19.2, respectively. Based on structure and physicochemical properties of rice starches extracted from different rice varieties, principal component analysis (PCA) results showed that these rice varieties could be clearly classified according to processing adaptability for cooked rice and rice cake. Copyright © 2017 Elsevier Ltd. All rights reserved.

Changes in Rice Grain Quality of Indica and Japonica Type Varieties Released in China from 2000 to 2014.

PubMed

Feng, Fan; Li, Yajun; Qin, Xiaoliang; Liao, Yuncheng; Siddique, Kadambot H M

2017-01-01

China is the first country to use heterosis successfully for commercial rice production. This study compared the main quality characteristics (head rice rate, chalky rice rate, chalkiness degree, gel consistency, amylose content, and length-to-width ratio) of 635 rice varieties (not including upland and glutinous rice) released from 2000 to 2014 to establish the quality status and offer suggestions for future rice breeding for grain quality in China. In the past 15 years, grain quality in japonica rice and indica hybrid rice has improved. In japonica rice, inbred varieties have increased head rice rates and decreased chalkiness degree over time, while hybrid rice varieties have decreased chalky rice rates and chalkiness degree. In indica hybrid rice, the chalkiness degree and amylose contents have decreased and gel consistency has increased. Improvements in grain quality in indica inbred rice have been limited, with some increases in head rice rate and decreases in chalky rice rate and amylose content. From 2010 to 2014, the percentage of indica varieties meeting the Grade III national standard of rice quality for different quality traits was low, especially for chalky rice rate and chalkiness degree. Japonica varieties have more superior grain quality than indica rice in terms of higher head rice rates and gel consistency, lower chalky rice rates and chalkiness degree, and lower amylose contents, which may explain why the Chinese prefer japonica rice. The japonica rice varieties, both hybrid and inbred, had similar grain qualities, but this varied in indica rice with the hybrid varieties having higher grain quality than inbred varieties due to significantly better head rice rates and lower chalkiness degree. For better quality rice in future, the chalky rice rate and chalkiness degree should be improved in japonica rice along with most of the quality traits in indica rice.

Impact of volunteer rice infestation on yield and grain quality of rice.

PubMed

Singh, Vijay; Burgos, Nilda R; Singh, Shilpa; Gealy, David R; Gbur, Edward E; Caicedo, Ana L

2017-03-01

Volunteer rice (Oryza sativa L.) grains may differ in physicochemical traits from cultivated rice, which may reduce the quality of harvested rice grain. To evaluate the effect of volunteer rice on cultivated rice, fields were surveyed in Arkansas in 2012. Cropping history that included hybrid cultivars in the previous two years (2010 and 2011) had higher volunteer rice infestation (20%) compared with fields planted previously with inbred rice (5.5%). The total grain yield of rice was reduced by 0.4% for every 1% increase in volunteer rice density. The grain quality did not change in fields planted with the same cultivar for three years. Volunteer rice density of at least 7.6% negatively impacted the head rice and when infestation reached 17.7%, it also reduced the rice grain yield. The protein and amylose contents of rice were not affected until volunteer rice infestation exceeded 30%. Crop rotation systems that include hybrid rice are expected to have higher volunteer rice infestation than systems without hybrid rice. It is predicted that, at 8% infestation, volunteer rice will start to impact head rice yield and will reduce total yield at 18% infestation. It could alter the chemical quality of rice grain at >30% infestation. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Contributions to the History of Astronomy, Vol. 3. (German Title: Beiträge zur Astronomiegeschichte, Band 3)

NASA Astrophysics Data System (ADS)

Dick, Wolfgang R.; Hamel, Jürgen

The main papers of this issue deal with previously unknown details of the foundation of the astronomical observatories in Gotha and in Königsberg (with numerous original documents by F.W. Bessel), with the Mecklenburg ordnance survey (1853-1873, with previously unknown letters by C.F. Gauss), with the merits of the Leipzig astronomer G.A. Jahn, with the internationality of the Astronomische Gesellschaft, and with early, previously little noted works on the expansion of the Universe. The issue contains a description of the important collection of sundials in the Kassel museum, discussions about the Medieval ``Phantom Period'', about Goethe's description of the zodiacal light, as well as obituaries and book reviews. Most papers in German, one in English.

Investigating differences in light stable isotopes between Thai jasmine rice and Sungyod rice

NASA Astrophysics Data System (ADS)

Kukusamude, C.; Kongsri, S.

2017-10-01

We report the differences in light stable isotopes between two kinds of Thai rice (Thai jasmine and Sungyod rice). Thai jasmine rice and Sungyod rice were cultivated in the northeast and the south of Thailand. Light isotopes including 13C, 15N and 18O of Thai jasmine rice and Sungyod rice samples were carried out using isotope ratio mass spectrometry (IRMS). Thai jasmine rice (Khao Dawk Mali 105) was cultivated from Thung Kula Rong Hai area, whereas Sungyod rice was cultivated from Phathalung province. Hypothesis testing of difference of each isotope between Thai jasmine rice and Sungyod rice was also studied. The study was the feasibility test whether the light stable isotopes can be the variables to identify Thai jasmine rice and Sungyod rice. The result shows that there was difference in the isotope patterns of Thai jasmine rice and Sungyod rice. Our results may provide the useful information in term of stable isotope profiles of Thai rice.

Broken rice kernels and the kinetics of rice hydration and texture during cooking.

PubMed

Saleh, Mohammed; Meullenet, Jean-Francois

2013-05-01

During rice milling and processing, broken kernels are inevitably present, although to date it has been unclear as to how the presence of broken kernels affects rice hydration and cooked rice texture. Therefore, this work intended to study the effect of broken kernels in a rice sample on rice hydration and texture during cooking. Two medium-grain and two long-grain rice cultivars were harvested, dried and milled, and the broken kernels were separated from unbroken kernels. Broken rice kernels were subsequently combined with unbroken rice kernels forming treatments of 0, 40, 150, 350 or 1000 g kg(-1) broken kernels ratio. Rice samples were then cooked and the moisture content of the cooked rice, the moisture uptake rate, and rice hardness and stickiness were measured. As the amount of broken rice kernels increased, rice sample texture became increasingly softer (P < 0.05) but the unbroken kernels became significantly harder. Moisture content and moisture uptake rate were positively correlated, and cooked rice hardness was negatively correlated to the percentage of broken kernels in rice samples. Differences in the proportions of broken rice in a milled rice sample play a major role in determining the texture properties of cooked rice. Variations in the moisture migration kinetics between broken and unbroken kernels caused faster hydration of the cores of broken rice kernels, with greater starch leach-out during cooking affecting the texture of the cooked rice. The texture of cooked rice can be controlled, to some extent, by varying the proportion of broken kernels in milled rice. © 2012 Society of Chemical Industry.

Migration Issues in the Democratic Republic of Congo

DTIC Science & Technology

2011-03-01

acts as a form of insurance against failures in the local economy and job market , as the household is receiving income from differing locations and...E. S. (1966). A Theory of Migration. Demography, 47 - 57. 35. Lewis, W. A. (1954). Economic Development with Unlimited Supplies of Labour . The... Norway . 47. Rice, C. (2005, December 11). The Promise of Democratic Peace: Why Promoting Freedom is the Only Realistic Path to Security. The Washington

Gene flow from weedy red rice (Oryza sativa L.) to cultivated rice and fitness of hybrids.

PubMed

Shivrain, Vinod K; Burgos, Nilda R; Gealy, David R; Sales, Marites A; Smith, Kenneth L

2009-10-01

Gene transfer from weeds to crops could produce weedy individuals that might impact upon the evolutionary dynamics of weedy populations, the persistence of escaped genes in agroecosystems and approaches to weed management and containment of transgenic crops. The present aim was to quantify the gene flowrate from weedy red rice to cultivated rice, and evaluate the morphology, phenology and fecundity of resulting hybrids. Field experiments were conducted at Stuttgart and Rohwer, Arkansas, USA. Twelve red rice accessions and an imazethapyr-resistant rice (Imi-R; Clearfield) were used. Hybrids between Imi-R rice x red rice were 138-150 cm tall and flowered 1-5 days later than the rice parent, regardless of the red rice parent. Hybrids produced 20-50% more seed than the rice parent, but had equivalent seed production to the majority of red rice parents. Seeds of all hybrids were red, pubescent and dehisced at maturity. For the majority of hybrids, seed germination was higher than that of the red rice parent. The gene flowrate from red rice to rice was 0.01-0.2% and differed by red rice biotype. The hybrids had higher fecundity and potential competitive ability than the rice parent, and in some cases also the red rice parent. Red rice plants are vectors of gene flow back to cultivated rice and other weedy populations. The progeny of red rice hybrids from cultivated rice mother plants have higher chances of persistence than those from red rice mother plants. Gene flow mitigation strategies should consider this scenario. Copyright 2009 Society of Chemical Industry.

A Navy Escrow Account: Increasing Financial Flexibility

DTIC Science & Technology

2003-06-01

generate cost savings and the means by which those funds could be recapitalized. The creation of an escrow account coincides with the Navy’s Sea...Navy escrow account , as envisioned, would provide financial managers with the incentive to generate cost savings and the means by which those funds...MONTEREY, CALIFORNIA CONRAD ESSAY A Navy Escrow Account : Increasing Financial Flexibility By: Commander Marcus A. Pritchard

Quenching of Emission and of Photochemistry for Aqueous Rh(NH3)5Cl(2+).

DTIC Science & Technology

1979-04-01

Hueneme, CalifornIa 93041 Attn: Dr. R. 3. Marcus 1 Attn: Mr. W. S. Haynes ONR Branch Offi ce Professor 0. Hein7 760 Market Street , Rm. 447...Peebles 1 WashI ngton, D.C. 20380 Directo r, Naval Research Laboratory Offi ce of Naval Researc hWashington, D.C. 20390 Arlington, VIrginia 22217

78 FR 18340 - The Neiman Marcus Group, Inc.; Dr.Jays.com, Inc., Eminent, Inc.; Analysis of Proposed Consent...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-26

... heightened security screening. As a result, we encourage you to submit your comments online. To make sure...'' or ``Eminent, File No. 122 3065'' on your comment and file your comment online at https://ftcpublic... prefer to file your comment on paper, mail or deliver your comment to the following address: Federal...

77 FR 6065 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-07

... day public comment period. L-DEO plans to use one source vessel, the R/V Marcus G. Langseth (Langseth... (km) 1,511.9 nautical miles [nmi]) of transect lines (including turns) in the study area. The seismic... involve one source vessel, the Langseth. The Langseth will deploy an array of 36 airguns as an energy...

76 FR 77782 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-14

...) during the study. The shot interval will be relatively short, approximately 15 to 18 seconds (s), for the... than the one provided here. Comments sent via email, including all attachments, must not exceed a 10... 21, 2012. L-DEO plans to use one source vessel, the R/V Marcus G. Langseth (Langseth) and a seismic...

Sorry Dave, I’m Afraid I Can’t Do That: Explaining Unachievable Robot Tasks using Natural Language

DTIC Science & Technology

2013-06-24

processing components used by Brooks et al. [6]: the Bikel parser [3] combined with the null element (understood subject) restoration of Gabbard et al...Intelligent Robots and Systems (IROS), pages 1988 – 1993, 2010. [12] Ryan Gabbard , Mitch Marcus, and Seth Kulick. Fully parsing the Penn Treebank. In Human

Geometric Computation of Human Gyrification Indexes from Magnetic Resonance Images

DTIC Science & Technology

2009-04-01

GEOMETRIC COMPUTATION OF HUMAN GYRIFICATION INDEXES FROM MAGNETIC RESONANCE IMAGES By Shu Su Tonya White Marcus Schmidt Chiu-Yen Kao and Guillermo...00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Geometric Computation of Human Gyrification Indexes from Magnetic Resonance Images 5a. CONTRACT NUMBER... Geometric Computation of Gyrification Indexes Chiu-Yen Kao 1 Geometric Computation of Human Gyrification

Unclassified Publications of Lincoln Laboratory 1 January - 31 December 1994, Volume 20.

DTIC Science & Technology

1994-12-31

J. Ehrlich, DJ. Hollis, M.A. Kosicki, B.B. Powdrill, T. Beattie, K. Smith, S. Varma, R. Gangadharan, R. Mallik , A. Burke, B.E. Wallace, D...JA-6972, JA-7028 Mallik , A., JA-7164 Manfra, M.J., JA-7027, MS-10604 Mankiewich, P.M., JA-7001 Maragos, P., JA-6764, JA-6888 Marcus, S., JA-6898

Dog Is a Dog Is a Dog: Infant Rule Learning Is Not Specific to Language

ERIC Educational Resources Information Center

Saffran, Jenny R.; Pollak, Seth D.; Seibel, Rebecca L.; Shkolnik, Anna

2007-01-01

Human infants possess powerful learning mechanisms used for the acquisition of language. To what extent are these mechanisms domain specific? One well-known infant language learning mechanism is the ability to detect and generalize rule-like similarity patterns, such as ABA or ABB [Marcus, G. F., Vijayan, S., Rao, S. B., & Vishton, P. M. (1999).…

Marcuse, Bloch and Freire: Reinvigorating a Pedagogy of Hope

ERIC Educational Resources Information Center

Van Heertum, Richard

2006-01-01

Critique of the current order of things is a necessary starting point for any project for radical change. Without an analysis of what is wrong, it is hard to convince anyone that change is necessary. And yet critique alone rarely inspires people to act. We need something to fight for as well as against. The article looks at the centrality of hope…

Toward a Broader Dialectic: Joining Marxism with Mailer to Forge a Multilectics That Advances Teaching and Learning

ERIC Educational Resources Information Center

Fellner, Gene

2014-01-01

I contrast the lenses that Norman Mailer, Herbert Marcuse, and Karl Marx bring to their analyses of social life, exploring the contributions and limits of their respective approaches. I then propose what I call a "multilectical" theoretical lens that encompasses the strengths of all three and leans on the insights of post-Marxist…

Information from Multiple Modalities Helps 5-Month-Olds Learn Abstract Rules

ERIC Educational Resources Information Center

Frank, Michael C.; Slemmer, Jonathan A.; Marcus, Gary F.; Johnson, Scott P.

2009-01-01

By 7 months of age, infants are able to learn rules based on the abstract relationships between stimuli ( Marcus et al., 1999 ), but they are better able to do so when exposed to speech than to some other classes of stimuli. In the current experiments we ask whether multimodal stimulus information will aid younger infants in identifying abstract…

An update on the use of co-products from the milling of rice in value added food products

USDA-ARS?s Scientific Manuscript database

Because of the huge quantity of rice produced annually, milled-rice co-products; such as, rice bran, rice oil, rice wax, rice flour, and rice hull are plentiful and readily available. These co-products could be valuable sources of food ingredients, but they have been vastly under-utilized. Rice bra...

[The nurse answers for health in social inequalities: the development of the nursing critical paradigm.].

PubMed

Rocco, Gennaro; Stievano, Alessandro

2007-01-01

Until the early Eighties, critical social theory as a philosophical orientation informing nursing science, theory development and practice did not exist. Interest on this topic began to arise only after the mid-Eighties. In fact, nursing scholars questioned the validity of empiricism as the historical foundation for nursing science and the limitations of interpretivism in strengthening nursing knowledge, and thus started to focus on the lack of epistemological perspectives in nursing, giving particular prominence to the peculiar social, political, historical and economic conditions involving those who needed nursing care. The theoretical reflection began to develop, like the empirical paradigm, the post-positivist paradigm and, later, the interpretative paradigm, expanded thanks to the early works by Martha Rogers and Rosemarie Rizzo Parse, were seen as unable to address issues related to power inequities, structural constraints and oppression suffered by vulnerable groups such as the homeless, mental health individuals, people affected by HIV+ and other infectious diseases, unemployed, etc.. Empiricism and interpretative paradigms did not manage to bridge the gap between theory and praxis, and a new theoretical and philosophical approach gradually gained ground. This paradigm, based on critical social theory, was developed by distinguished scholars and intellectuals, such as Max Horkheimer, Theodor Adorno, Herbert Marcuse of the Frankfurt School in the Thirties, and, in recent years, by Giddens, Bourdieu, Foucault, Habermas. On this social field the first works of Allen, Thompson, Stevens, Campbell and Bunting, Kendall, allowed to work out a new paradigmatic nursing approach that would have predicted the employment of the critical theory for particular nursing aspects, as a conceptual framework for nursing education, as a paradigm to carry out participatory action-research and for the development of the discipline. The purpose of this article was to describe this new paradigmatic nursing approach. In this way, we hope to give emphasis to the epistemological debate that should characterize a discipline that has undertaken by now, also in Italy, the characteristics of a scientific and a fully epistemological validity.

A computational study of photo-induced electron transfer rate constants in subphthalocyanine/C60 organic photovoltaic materials via Fermi's golden rule

NASA Astrophysics Data System (ADS)

Lee, Myeong H.; Dunietz, Barry D.; Geva, Eitan

2014-03-01

We present a methodology to obtain the photo-induced electron transfer rate constant in organic photovoltaic (OPV) materials within the framework of Fermi's golden rule, using inputs obtained from first-principles electronic structure calculation. Within this approach, the nuclear vibrational modes are treated quantum-mechanically and a short-time approximation is avoided in contrast to the classical Marcus theory where these modes are treated classically within the high-temperature and short-time limits. We demonstrate our methodology on boron-subphthalocyanine-chloride/C60 OPV system to determine the rate constants of electron transfer and electron recombination processes upon photo-excitation. We consider two representative donor/acceptor interface configurations to investigate the effect of interface configuration on the charge transfer characteristics of OPV materials. In addition, we determine the time scale of excited states population by employing a master equation after obtaining the rate constants for all accessible electronic transitions. This work is pursued as part of the Center for Solar and Thermal Energy Conversion, an Energy Frontier Research Center funded by the US Department of Energy Office of Science, Office of Basic Energy Sciences under 390 Award No. DE-SC0000957.

Charge-transfer dynamics and nonlocal dielectric permittivity tuned with metamaterial structures as solvent analogues

NASA Astrophysics Data System (ADS)

Lee, Kwang Jin; Xiao, Yiming; Woo, Jae Heun; Kim, Eunsun; Kreher, David; Attias, André-Jean; Mathevet, Fabrice; Ribierre, Jean-Charles; Wu, Jeong Weon; André, Pascal

2017-07-01

Charge transfer (CT) is a fundamental and ubiquitous mechanism in biology, physics and chemistry. Here, we evidence that CT dynamics can be altered by multi-layered hyperbolic metamaterial (HMM) substrates. Taking triphenylene:perylene diimide dyad supramolecular self-assemblies as a model system, we reveal longer-lived CT states in the presence of HMM structures, with both charge separation and recombination characteristic times increased by factors of 2.4 and 1.7--that is, relative variations of 140 and 73%, respectively. To rationalize these experimental results in terms of driving force, we successfully introduce image dipole interactions in Marcus theory. The non-local effect herein demonstrated is directly linked to the number of metal-dielectric pairs, can be formalized in the dielectric permittivity, and is presented as a solid analogue to local solvent polarity effects. This model and extra PH3T:PC60BM results show the generality of this non-local phenomenon and that a wide range of kinetic tailoring opportunities can arise from substrate engineering. This work paves the way toward the design of artificial substrates to control CT dynamics of interest for applications in optoelectronics and chemistry.

Charge carrier mobility in conjugated organic polymers: simulation of an electron mobility in a carbazole-benzothiadiazole-based polymer

NASA Astrophysics Data System (ADS)

Li, Yaping; Lagowski, Jolanta B.

2011-08-01

Inorganic (mostly silicon based) solar cells are important devices that are used to solve the world energy and environmental needs. Now days, organic solar cells are attracting considerable attention in the field of photovoltaic cells because of their low cost and processing flexibility. Often conjugated polymers are used in the construction of the organic solar cells. We study the conjugated polymers' charge transport using computational approach that involves the use of the density functional theory (DFT), semiempirical (ZINDO), and Monte Carlo (MC) theoretical methods in order to determine their transfer integrals, reorganization energies, transfer rates (with the use of Marcus-Hush equation) and mobilities. We employ the experimentally determined three dimensional (3D) structure of poly(9,9'-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) to estimate the electron mobility in a similar co-alternating polymer consisting of carbazole and benzothiadiazole units (C8BT). In agreement with our previous work, we found that including an orientational disorder in the crystal reduces the electron mobility in C8BT. We hope that the proposed computational approach can be used to predict charge mobility in organic materials that are used in solar cells.

Electron transfer and reaction mechanism of laccases.

PubMed

Jones, Stephen M; Solomon, Edward I

2015-03-01

Laccases are part of the family of multicopper oxidases (MCOs), which couple the oxidation of substrates to the four electron reduction of O2 to H2O. MCOs contain a minimum of four Cu's divided into Type 1 (T1), Type 2 (T2), and binuclear Type 3 (T3) Cu sites that are distinguished based on unique spectroscopic features. Substrate oxidation occurs near the T1, and electrons are transferred approximately 13 Å through the protein via the Cys-His pathway to the T2/T3 trinuclear copper cluster (TNC), where dioxygen reduction occurs. This review outlines the electron transfer (ET) process in laccases, and the mechanism of O2 reduction as elucidated through spectroscopic, kinetic, and computational data. Marcus theory is used to describe the relevant factors which impact ET rates including the driving force, reorganization energy, and electronic coupling matrix element. Then, the mechanism of O2 reaction is detailed with particular focus on the intermediates formed during the two 2e(-) reduction steps. The first 2e(-) step forms the peroxide intermediate, followed by the second 2e(-) step to form the native intermediate, which has been shown to be the catalytically relevant fully oxidized form of the enzyme.

Ultrafast fluorescence quenching dynamics of Atto655 in the presence of N-acetyltyrosine and N-acetyltryptophan in aqueous solution: proton-coupled electron transfer versus electron transfer.

PubMed

Zhang, Ying; Yuan, Shuwei; Lu, Rong; Yu, Anchi

2013-06-20

We studied the ultrafast fluorescence quenching dynamics of Atto655 in the presence of N-acetyltyrosine (AcTyr) and N-acetyltryptophan (AcTrp) in aqueous solution with femtosecond transient absorption spectroscopy. We found that the charge-transfer rate between Atto655 and AcTyr is about 240 times smaller than that between Atto655 and AcTrp. The pH value and D2O dependences of the excited-state decay kinetics of Atto655 in the presence of AcTyr and AcTrp reveal that the quenching of Atto655 fluorescence by AcTyr in aqueous solution is via a proton-coupled electron-transfer (PCET) process and that the quenching of Atto655 fluorescence by AcTrp in aqueous solution is via an electron-transfer process. With the version of the semiclassical Marcus ET theory, we derived that the electronic coupling constant for the PCET reaction between Atto655 and AcTyr in aqueous solution is 8.3 cm(-1), indicating that the PCET reaction between Atto655 and AcTyr in aqueous solution is nonadiabatic.

[Effects of rice-duck mutualistic organic farming on rice quality in the Yellow River Delta, China.

PubMed

Wang, Jian Lin; Li, Jie; Cao, Yuan Yuan

2016-07-01

Three cultivation models including rice-duck mutualistic, manual weeding and conventional rice farming were designed in the Yellow River Delta area to study the effects on rice milling quality, appearance quality, cooking and eating quality, and sanitation quality. The results showed that compared to conventional rice farming, the rice-duckmutualistic treatment increased grain width and brown rice rate, milled rice rate, head rice rate and reduced the chalkiness. This was mainly due to the increase of panicle numbers and grain mass and the decrease of the inferior grains. Due to the application of organic manure, the gel consistency increased, amylose and protein contents decreased, and the rice taste improved under rice-duck mutualistic and manual weeding cultivation treatments. As no chemical fertilizers and pesticides were applied under rice-duck mutualistic and manual weeding treatments, pesticide residues were greatly reduced or even not detected. Rice duck farming could improve the quality of rice and protect the environment, which would be a good ecological technology for high quality rice production.

Effect of cooling of cooked white rice on resistant starch content and glycemic response.

PubMed

Sonia, Steffi; Witjaksono, Fiastuti; Ridwan, Rahmawati

2015-01-01

Cooling of cooked starch is known to cause starch retrogradation which increases resistant starch content. This study aimed to determine the effect of cooling of cooked white rice on resistant starch content and glycemic response in healthy subjects. Resistant starch contents were analyzed on freshly cooked white rice (control rice), cooked white rice cooled for 10 hours at room temperature (test rice I), and cooked white rice cooled for 24 hours at 4°C then reheated (test rice II). The results showed that resistant starch contents in control rice, test rice I, and test rice II were 0.64 g/100 g, 1.30 g/100 g, and 1.65 g/100 g, respectively. Test rice II had higher resistant starch content than test rice I, hence used in the clinical study along with control rice to characterize glycemic response in 15 healthy adults. The clinical study was a randomized, single-blind crossover study. In the clinical study, test rice II significantly lowered glycemic response compared with control rice (125±50.1 vs 152±48.3 mmol.min/L, respectively; p=0.047). In conclusion, cooling of cooked white rice increased resistant starch content. Cooked white rice cooled for 24 hours at 4°C then reheated lowered glycemic response compared with freshly cooked white rice.

Effect of rice-cooking water to the daily arsenic intake in Bangladesh: results of field surveys and rice-cooking experiments.

PubMed

Ohno, K; Matsuo, Y; Kimura, T; Yanase, T; Rahman, M H; Magara, Y; Matsushita, T; Matsui, Y

2009-01-01

The effect of rice-cooking water to the daily arsenic intake of Bangladeshi people was investigated. At the first field survey, uncooked rice and cooked rice of 29 families were collected. Their arsenic concentrations were 0.22+/-0.11 and 0.26+/-0.15 mg/kg dry wt, respectively. In 15 families, arsenic concentration in rice increased after cooking. Good correlation (R(2)=0.89) was observed between arsenic in rice-cooking water and the difference of arsenic concentration in rice by cooking. In the second survey, we collected one-day duplicated food of 18 families. As a result, we estimated that six of 18 families likely used the arsenic contaminated water for cooking rice even they drank less arsenic-contaminated water for drinking purpose. We also conducted rice-cooking experiments in the laboratory, changing arsenic concentration in rice-cooking water. Clear linear relationships were obtained between the arsenic in rice-cooking water and the difference of arsenic concentration in rice by cooking. Factors that affect arsenic concentration in cooked rice are suggested as follows: (1) arsenic concentration in uncooked rice, (2) that in rice-cooking water, (3) difference in water content of rice before and after cooking, and (4) types of rice, especially, the difference between parboiled and non-parboiled rice.

7 CFR 1412.49 - Apportionment of long and medium grain rice.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 10 2012-01-01 2012-01-01 false Apportionment of long and medium grain rice. 1412.49... and Peanuts 2008 through 2012 § 1412.49 Apportionment of long and medium grain rice. (a) Rice base...) Medium grain rice. Medium grain rice includes short grain rice. (c) Owners on a farm will elect rice base...

7 CFR 1412.49 - Apportionment of long and medium grain rice.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 10 2010-01-01 2010-01-01 false Apportionment of long and medium grain rice. 1412.49... and Peanuts 2008 through 2012 § 1412.49 Apportionment of long and medium grain rice. (a) Rice base...) Medium grain rice. Medium grain rice includes short grain rice. (c) Owners on a farm will elect rice base...

7 CFR 1412.49 - Apportionment of long and medium grain rice.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 10 2013-01-01 2013-01-01 false Apportionment of long and medium grain rice. 1412.49... and Peanuts 2008 Through 2012 § 1412.49 Apportionment of long and medium grain rice. (a) Rice base...) Medium grain rice. Medium grain rice includes short grain rice. (c) Owners on a farm will elect rice base...

7 CFR 1412.49 - Apportionment of long and medium grain rice.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 10 2011-01-01 2011-01-01 false Apportionment of long and medium grain rice. 1412.49... and Peanuts 2008 through 2012 § 1412.49 Apportionment of long and medium grain rice. (a) Rice base...) Medium grain rice. Medium grain rice includes short grain rice. (c) Owners on a farm will elect rice base...

7 CFR 1412.49 - Apportionment of long and medium grain rice.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 10 2014-01-01 2014-01-01 false Apportionment of long and medium grain rice. 1412.49... and Peanuts 2008 Through 2012 § 1412.49 Apportionment of long and medium grain rice. (a) Rice base...) Medium grain rice. Medium grain rice includes short grain rice. (c) Owners on a farm will elect rice base...

Comparative analysis of the root transcriptomes of cultivated and wild rice varieties in response to Magnaporthe oryzae infection revealed both common and species-specific pathogen responses.

PubMed

Tian, Lei; Shi, Shaohua; Nasir, Fahad; Chang, Chunling; Li, Weiqiang; Tran, Lam-Son Phan; Tian, Chunjie

2018-04-20

Magnaporthe oryzae, the causal fungus of rice blast disease, negatively impacts global rice production. Wild rice (Oryza rufipogon), a relative of cultivated rice (O. sativa), possesses unique attributes that enable it to resist pathogen invasion. Although wild rice represents a major resource for disease resistance, relative to current cultivated rice varieties, no prior studies have compared the immune and transcriptional responses in the roots of wild and cultivated rice to M. oryzae. In this study, we showed that M. oryzae could act as a typical root-infecting pathogen in rice, in addition to its common infection of leaves, and wild rice roots were more resistant to M. oryzae than cultivated rice roots. Next, we compared the differential responses of wild and cultivated rice roots to M. oryzae using RNA-sequencing (RNA-seq) to unravel the molecular mechanisms underlying the enhanced resistance of the wild rice roots. Results indicated that both common and genotype-specific mechanisms exist in both wild and cultivated rice that are associated with resistance to M. oryzae. In wild rice, resistance mechanisms were associated with lipid metabolism, WRKY transcription factors, chitinase activities, jasmonic acid, ethylene, lignin, and phenylpropanoid and diterpenoid metabolism; while the pathogen responses in cultivated rice were mainly associated with phenylpropanoid, flavone and wax metabolism. Although modulations in primary metabolism and phenylpropanoid synthesis were common to both cultivated and wild rice, the modulation of secondary metabolism related to phenylpropanoid synthesis was associated with lignin synthesis in wild rice and flavone synthesis in cultivated rice. Interestingly, while the expression of fatty acid and starch metabolism-related genes was altered in both wild and cultivated rice in response to the pathogen, changes in lipid acid synthesis and lipid acid degradation were dominant in cultivated and wild rice, respectively. The response mechanisms to M. oryzae were more complex in wild rice than what was observed in cultivated rice. Therefore, this study may have practical implications for controlling M. oryzae in rice plantings and will provide useful information for incorporating and assessing disease resistance to M. oryzae in rice breeding programs.

On the Theory of Evolution Versus the Concept of Evolution: Three Observations

PubMed Central

Paz-y-Miño C., Guillermo

2016-01-01

Here we address three misconceptions stated by Rice et al. in their observations of our article Paz-y-Miño and Espinosa (Evo Edu Outreach 2:655-675, 2009), published in this journal. The five authors titled their note “The Theory of Evolution is Not an Explanation for the Origin of Life.” First, we argue that it is fallacious to believe that because the formulation of the theory of evolution, as conceived in the 1800s, did not include an explanation for the origin of life, nor of the universe, the concept of evolution would not allow us to hypothesize the possible beginnings of life and its connections to the cosmos. Not only Stanley Miller's experiments of 1953 led scientists to envision a continuum from the inorganic world to the origin and diversification of life, but also Darwin's own writings of 1871. Second, to dismiss the notion of Rice et al. that evolution does not provide explanations concerning the universe or the cosmos, we identify compelling scientific discussions on the topics: Zaikowski et al. (Evo Edu Outreach 1:65–73, 2008), Krauss (Evo Edu Outreach 3:193–197, 2010), Peretó et al. (Orig Life Evol Biosph 39:395–406, 2009) and Follmann and Brownson (Naturwissenschaften 96:1265-1292, 2009). Third, although we acknowledge that the term Darwinism may not be inclusive of all new discoveries in evolution, and also that creationists and Intelligent Designers hijack the term to portray evolution as ideology, we demonstrate that there is no statistical evidence suggesting that the word Darwinism interferes with public acceptance of evolution, nor does the inclusion of the origin of life or the universe within the concept of evolution. We examine the epistemological and empirical distinction between the theory of evolution and the concept of evolution and conclude that, although the distinction is important, it should not compromise scientific logic. PMID:26949441

Mapping paddy rice planting area in rice-wetland coexistent areas through analysis of Landsat 8 OLI and MODIS images

PubMed Central

Zhou, Yuting; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Wang, Jie; Li, Xiangping

2016-01-01

Accurate and up-to-date information on the spatial distribution of paddy rice fields is necessary for the studies of trace gas emissions, water source management, and food security. The phenology-based paddy rice mapping algorithm, which identifies the unique flooding stage of paddy rice, has been widely used. However, identification and mapping of paddy rice in rice-wetland coexistent areas is still a challenging task. In this study, we found that the flooding/transplanting periods of paddy rice and natural wetlands were different. The natural wetlands flood earlier and have a shorter duration than paddy rice in the Panjin Plain, a temperate region in China. We used this asynchronous flooding stage to extract the paddy rice planting area from the rice-wetland coexistent area. MODIS Land Surface Temperature (LST) data was used to derive the temperature-defined plant growing season. Landsat 8 OLI imagery was used to detect the flooding signal and then paddy rice was extracted using the difference in flooding stages between paddy rice and natural wetlands. The resultant paddy rice map was evaluated with in-situ ground-truth data and Google Earth images. The estimated overall accuracy and Kappa coefficient were 95% and 0.90, respectively. The spatial pattern of OLI-derived paddy rice map agrees well with the paddy rice layer from the National Land Cover Dataset from 2010 (NLCD-2010). The differences between RiceLandsat and RiceNLCD are in the range of ±20% for most 1-km grid cell. The results of this study demonstrate the potential of the phenology-based paddy rice mapping algorithm, via integrating MODIS and Landsat 8 OLI images, to map paddy rice fields in complex landscapes of paddy rice and natural wetland in the temperate region. PMID:27688742

Mapping paddy rice planting area in rice-wetland coexistent areas through analysis of Landsat 8 OLI and MODIS images.

PubMed

Zhou, Yuting; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Wang, Jie; Li, Xiangping

2016-04-01

Accurate and up-to-date information on the spatial distribution of paddy rice fields is necessary for the studies of trace gas emissions, water source management, and food security. The phenology-based paddy rice mapping algorithm, which identifies the unique flooding stage of paddy rice, has been widely used. However, identification and mapping of paddy rice in rice-wetland coexistent areas is still a challenging task. In this study, we found that the flooding/transplanting periods of paddy rice and natural wetlands were different. The natural wetlands flood earlier and have a shorter duration than paddy rice in the Panjin Plain, a temperate region in China. We used this asynchronous flooding stage to extract the paddy rice planting area from the rice-wetland coexistent area. MODIS Land Surface Temperature (LST) data was used to derive the temperature-defined plant growing season. Landsat 8 OLI imagery was used to detect the flooding signal and then paddy rice was extracted using the difference in flooding stages between paddy rice and natural wetlands. The resultant paddy rice map was evaluated with in-situ ground-truth data and Google Earth images. The estimated overall accuracy and Kappa coefficient were 95% and 0.90, respectively. The spatial pattern of OLI-derived paddy rice map agrees well with the paddy rice layer from the National Land Cover Dataset from 2010 (NLCD-2010). The differences between Rice Landsat and Rice NLCD are in the range of ±20% for most 1-km grid cell. The results of this study demonstrate the potential of the phenology-based paddy rice mapping algorithm, via integrating MODIS and Landsat 8 OLI images, to map paddy rice fields in complex landscapes of paddy rice and natural wetland in the temperate region.

Water-saving technologies affect the grain characteristics and recovery of fine-grain rice cultivars in semi-arid environment.

PubMed

Jabran, Khawar; Riaz, Muhammad; Hussain, Mubshar; Nasim, Wajid; Zaman, Umar; Fahad, Shah; Chauhan, Bhagirath Singh

2017-05-01

Growing rice with less water is direly needed due to declining water sources worldwide, but using methods that require less water inputs can have an impact on grain characteristics and recovery. A 2-year field study was conducted to evaluate the impact of conventionally sown flooded rice and low-water-input rice systems on the grain characteristics and recovery of fine rice. Three fine grain rice cultivars-Super Basmati, Basmati 2000, and Shaheen Basmati-were grown under conventional flooded transplanted rice (CFTR), alternate wetting and drying (AWD), and aerobic rice systems. Grain characteristics and rice recovery were significantly influenced by different water regimes (production systems). Poor milling, including the lowest percentage of brown (head) rice (65.3%) and polished (white) rice (64.2-66.9%) and the highest percentage of broken brown rice (10.2%), husk (24.5%-26.3%), polished broken rice (24.7%), and bran (11.0-12.5%), were recorded in the aerobic rice system sown with Shaheen Basmati. With a few exceptions, cultivars sown in CFTR were found to possess a higher percentage of brown (head) and polished (white) rice and they had incurred the least losses in the form of brown broken rice, husk, polished broken rice, and bran. In conclusion, better grain quality and recovery of rice can be attained by growing Super Basmati under the CFTR system. Growing Shaheen Basmati under low-water-input systems, the aerobic rice system in particular, resulted in poor grain characteristics tied with less rice recovery.

Feral rice from introgression of weedy rice genes into transgenic herbicide-resistant hybrid-rice progeny.

PubMed

Zhang, Jingxu; Kang, Ye; Valverde, Bernal E; Dai, Weimin; Song, Xiaoling; Qiang, Sheng

2018-06-05

Pollen-mediated herbicide-resistance transgene flow occurs bidirectionally between transgenic cultivated rice and weedy rice. The potential risk of weedy traits introgressing into hybrid rice is underestimated and poorly understood. Two of each glufosinate-resistant transgenic rice varieties and hybrid rice (F1) and their succeeding generations (F2-F4) were planted for three years in weedy-rice-free field plots adjacent to experimental weedy-rice fields. Weedy-rice-like (feral) plants, both glufosinate-resistant and with red-pericarp seed, were initially found only among the F3 generations of the two glufosinate-resistant transgenic hybrid rice. The composite fitness (an index based on eight productivity and weediness traits) of the feral progeny was significantly higher than that of glufosinate-resistant transgenic hybrid rice (the original female parent of feral progeny) under common monoculture garden conditions. Hybrid rice progeny segregated into individuals of variable height and extended flowering. Hybrid rice F2 generations had higher outcrossing rates by pollen reception (0.96%-1.65%) than their progenitors (0.07%-0.98%). Herbicide-resistant weedy rice can rapidly arise by pollen-mediated gene flow from weedy to transgenic hybrid rice. Their segregating pollen-receptive progeny pose greater agro-ecological risk than transgenic varieties. The safety assessment and management regulations for transgenic hybrid rice should take into account the risk of bidirectional gene flow.

Climate change and farmers’ cropping patterns in Cemoro watershed area, Central Java, Indonesia

NASA Astrophysics Data System (ADS)

Sugihardjo; Sutrisno, J.; Setyono, P.; Suntoro

2018-03-01

Cropping pattern applied by farmers is usually based on the availability of water. Farmers cultivate rice when water is available. If it is unavailable, farmers will choose to plant crops that need less water. Climate change greatly affects to farmers in determining the cropping pattern as it alters the rainfall pattern and distribution in the region. This condition requires farmers to adjust the cropping pattern so that they can do the farming successfully. This study aims to examine the application of cropping patterns applied by the farmers in the Cemoro Watershed, Central Java, Indonesia. Descriptive analysis approach is employed in this research. The results showed that farmers’ cropping pattern is not based on the availability of water. However, it adopts a habit that has been practiced since long time ago or just adopt others farmer's habit. The cropping pattern applied by irrigated paddy farmers in Cemoro watershed area consists of two types: rice-rice-rice and rice-rice-secondary crops. Among those two types, most farmers apply the rice-rice-rice pattern. Meanwhile, there are three cropping patterns applied in the rain-land, namely rice-rice-rice, rice-rice-secondary crop, and rice-rice-fallow. The majority of farmers apply the second pattern (rice-rice-secondary crops). It was also found that farmers’ cropping pattern was not in accordance with the recommendation of the local government.

Effects of Extraction Methods on Phytochemicals of Rice Bran Oils Produced from Colored Rice.

PubMed

Mingyai, Sukanya; Srikaeo, Khongsak; Kettawan, Aikkarach; Singanusong, Riantong; Nakagawa, Kiyotaka; Kimura, Fumiko; Ito, Junya

2018-02-01

Rice bran oil (RBO) especially from colored rice is rich in phytochemicals and has become popular in food, cosmetic, nutraceutical and pharmaceutical applications owing to its offering health benefits. This study determined the contents of phytochemicals including oryzanols, phytosterols, tocopherols (Toc) and tocotrienols (T3) in RBOs extracted using different methods namely cold-press extraction (CPE), solvent extraction (SE) and supercritical CO 2 extraction (SC-CO 2 ). Two colored rice, Red Jasmine rice (RJM, red rice) and Hom-nin rice (HN, black rice), were studied in comparison with the popular Thai fragrant rice Khao Dawk Mali 105 (KDML 105, white rice). RBOs were found to be the rich source of oryzanols, phytosterols, Toc and T3. Rice varieties had a greater effect on the phytochemicals concentrations than extraction methods. HN rice showed the significantly highest concentration of all phytochemicals, followed by RJM and KDML 105 rice, indicating that colored rice contained high concentration of phytochemicals in the oil than non-colored rice. The RBO samples extracted by the CPE method had a greater concentration of the phytochemicals than those extracted by the SC-CO 2 and SE methods, respectively. In terms of phytochemical contents, HN rice extracted using CPE method was found to be the best.

Diversity and population dynamics of pests and predators in irrigated rice fields with treated and untreated pesticide.

PubMed

Rattanapun, W

2012-01-01

The monitoring of rice pests and their predators in pesticide untreated and treated rice fields was conducted at the southern of Thailand. Twenty-two species in 15 families and 6 orders of rice pests were sampled from untreated rice field. For treated rice field, 22 species in 14 families and 5 orders of rice pest were collected. Regardless of treatment type, dominant species and individual number of rice pest varied to physiological stage of rice. Lepidopteran pests had highest infestation during the vegetative stage of rice growth, while hemipteran pests composed of hopper species (Hemipetra: Auchenorrhyncha) and heteropteran species (Hemiptera: Heteroptera) were dominant groups during the reproductive stage and grain formation and ripening stage of rice growth. In contrast, dominant species of predator did not change throughout rice growing season. There were 35 species in 25 families and seven orders and 40 species in 29 families and seven orders of predators collected from untreated and treated rice field, respectively. Major predators of both rice fields were Micraspis discolor (Fabricius) (Coleoptera: Coccinellidae), Tetragnatha sp. (Araneae: Tetragnathidae) and Agriocnemis pygmaea Rambur (Odonata: Agrionidae). The population dynamic of predators were not related with rice pest population in both treatments. However, the fluctuation of population pattern of rice pests in the untreated treatment were more distinctly synchronized with their predators than that of the treated treatment. There were no significant differences in the total number of rice pest and predator between two treatments at vegetative and reproductive stages of rice growth. Untreated rice field had a higher population number of predator and a lower population number of rice pest than that of treated rice field during grain formation and ripening stages. These results indicated the ago-ecosystem balance in rice fields could be produced through minimal pesticide application, in order to allow the natural balance between pests and their predators to be restored and maintained.

Introgression of resistance-conferring ALS mutations in herbicide-resistant weedy rice

USDA-ARS?s Scientific Manuscript database

Weedy red rice (Oryza sativa) competes aggressively with rice, reducing yields and grain quality. Clearfield™ rice, a nontransgenic, herbicide-resistant (HR) rice introduced in 2002 to control weedy rice, has resulted in some ALS-resistant weedy rice apparently due to gene flow. Studies were conduct...

Transgenic Bacillus thuringiensis (Bt) rice is safer to aquatic ecosystems than its non-transgenic counterpart.

PubMed

Li, Guangsheng; Wang, Yongmo; Liu, Biao; Zhang, Guoan

2014-01-01

Rice lines genetically modified with the crystal toxin genes from Bacillus thuringiensis (Bt) have experienced rapid development, with biosafety certificates for two Bt rice lines issued in 2009. There has still been no commercial release of these lines yet due to public concerns about human health and environmental risks. Some studies confirmed that Bt rice was as safe as conventional rice to non-target organisms when pesticides were not applied, however, pesticides are still required in Bt rice to control non-lepidopteran pests. In this study, we assessed the environmental effects of two Bt rice lines expressing either the cry1Ab/1Ac or cry2A genes, respectively, by using zooplanktons as indicator species under normal field management practices using pesticides when required. In the whole rice growing season, non-Bt rice was sprayed 5 times while Bt rice was sprayed 2 times, which ensured both rice achieved a normal yield. Field investigations showed that rice type (Bt and non-Bt) significantly influenced zooplankton abundance and diversity, which were up to 95% and 80% lower in non-Bt rice fields than Bt rice fields. Laboratory rearing showed that water from non-Bt rice fields was significantly less suitable for the survival and reproduction of Daphnia magna and Paramecium caudatum in comparison with water from Bt rice fields. Higher pesticide residues were detected in the water from non-Bt than Bt rice fields, accounting for the bad performance of zooplankton in non-Bt field water. Our results demonstrate that Bt rice is safer to aquatic ecosystems than non-Bt rice, and its commercialization will be beneficial for biodiversity restoration in rice-based ecosystems.

Transgenic Bacillus thuringiensis (Bt) Rice Is Safer to Aquatic Ecosystems than Its Non-Transgenic Counterpart

PubMed Central

Li, Guangsheng; Wang, Yongmo; Liu, Biao; Zhang, Guoan

2014-01-01

Rice lines genetically modified with the crystal toxin genes from Bacillus thuringiensis (Bt) have experienced rapid development, with biosafety certificates for two Bt rice lines issued in 2009. There has still been no commercial release of these lines yet due to public concerns about human health and environmental risks. Some studies confirmed that Bt rice was as safe as conventional rice to non-target organisms when pesticides were not applied, however, pesticides are still required in Bt rice to control non-lepidopteran pests. In this study, we assessed the environmental effects of two Bt rice lines expressing either the cry1Ab/1Ac or cry2A genes, respectively, by using zooplanktons as indicator species under normal field management practices using pesticides when required. In the whole rice growing season, non-Bt rice was sprayed 5 times while Bt rice was sprayed 2 times, which ensured both rice achieved a normal yield. Field investigations showed that rice type (Bt and non-Bt) significantly influenced zooplankton abundance and diversity, which were up to 95% and 80% lower in non-Bt rice fields than Bt rice fields. Laboratory rearing showed that water from non-Bt rice fields was significantly less suitable for the survival and reproduction of Daphnia magna and Paramecium caudatum in comparison with water from Bt rice fields. Higher pesticide residues were detected in the water from non-Bt than Bt rice fields, accounting for the bad performance of zooplankton in non-Bt field water. Our results demonstrate that Bt rice is safer to aquatic ecosystems than non-Bt rice, and its commercialization will be beneficial for biodiversity restoration in rice-based ecosystems. PMID:25105299

Theoretical study of the oxidation mechanisms of naphthalene initiated by hydroxyl radicals: the O2 addition reaction pathways.

PubMed

Shiroudi, A; Deleuze, M S; Canneaux, S

2015-05-28

Atmospheric oxidation of the naphthalene-OH adduct [C10H8OH]˙ (R1) by molecular oxygen in its triplet electronic ground state has been studied using density functional theory along with the B3LYP, ωB97XD, UM05-2x and UM06-2x exchange-correlation functionals. From a thermodynamic viewpoint, the most favourable process is O2 addition at the C2 position in syn mode, followed by O2 addition at the C2 position in anti mode, O2 addition at the C4 position in syn mode, and O2 addition at the C4 position in anti mode, as the second, third and fourth most favourable processes. The syn modes of addition at these positions are thermodynamically favoured over the anti ones by the formation of an intramolecular hydrogen bond between the hydroxyl and peroxy substituents. Analysis of the computed structures, bond orders and free energy profiles demonstrate that the reaction steps involved in the oxidation of the naphthalene-OH adduct by O2 satisfy Hammond's principle. Kinetic rate constants and branching ratios under atmospheric pressure and in the fall-off regime have been supplied, using transition state and RRKM theories. By comparison with experiment, these data confirm the relevance of a two-step reaction mechanism. Whatever the addition mode, O2 addition in C4 position is kinetically favoured over O2 addition in C2 position, in contrast with the expectations drawn from thermodynamics and reaction energies. Under a kinetic control of the reaction, and in line with the computed reaction energy barriers, the most efficient process is O2 addition at the C4 position in syn mode, followed by O2 addition at the C2 position in syn mode, O2 addition at the C4 position in anti mode, and O2 addition at the C2 position in anti mode as the second, third and fourth most rapid processes. The computed branching ratios also indicate that the regioselectivity of the reaction decreases with increasing temperatures and decreasing pressures.

Time-resolved gas-phase kinetic and quantum chemical studies of the reaction of silylene with oxygen.

PubMed

Becerra, Rosa; Bowes, Sarah-Jane; Ogden, J Steven; Cannady, J Pat; Adamovic, Ivana; Gordon, Mark S; Almond, Matthew J; Walsh, Robin

2005-08-07

Time-resolved kinetic studies of the reaction of silylene, SiH2, generated by laser flash photolysis of phenylsilane, have been carried out to obtain rate constants for its bimolecular reaction with O(2). The reaction was studied in the gas phase over the pressure range 1-100 Torr in SF(6) bath gas, at five temperatures in the range 297-600 K. The second order rate constants at 10 Torr were fitted to the Arrhenius equation: [see text] The decrease in rate constant values with increasing temperature, although systematic is very small. The rate constants showed slight increases in value with pressure at each temperature, but this was scarcely beyond experimental uncertainty. From estimates of Lennard-Jones collision rates, this reaction is occurring at ca. 1 in 20 collisions, almost independent of pressure and temperature. Ab initio calculations at the G3 level backed further by multi-configurational (MC) SCF calculations, augmented by second order perturbation theory (MRMP2), support a mechanism in which the initial adduct, H(2)SiOO, formed in the triplet state (T), undergoes intersystem crossing to the more stable singlet state (S) prior to further low energy isomerisation processes leading, via a sequence of steps, ultimately to dissociation products of which the lowest energy pair are H2O+SiO. The decomposition of the intermediate cyclo-siladioxirane, via O-O bond fission, plays an important role in the overall process. The bottleneck for the overall process appears to be the T-->S process in H2SiOO. This process has a small spin-orbit coupling matrix element, consistent with an estimate of its rate constant of 1x10(9) s-1 obtained with the aid of RRKM theory. This interpretation preserves the idea that, as in its reactions in general, SiH2 initially reacts at the encounter rate with O2. The low values for the secondary reaction barriers on the potential energy surface account for the lack of an observed pressure dependence. Some comparisons are drawn with the reactions of CH2+O2 and SiCl2+O2.

The Mercantile Business Coalition: A Narrative Analysis of a Learning Organization in an African American Community

ERIC Educational Resources Information Center

Harrell, Alma S.

2013-01-01

"A race that is solely dependent upon another for its economic existences sooner or later dies," this quote by Marcus Garvey highlighted the need for African American communities to think about the importance of economic development. This message was also heard by African Americans as early as the 1700s. Not only was the message about…

First Approach of Pneumatic Anthropomorphic Hand

DTIC Science & Technology

2001-10-25

1 o f 3 FIRST APPROACH OF PNEUMATIC ANTHROPOMORPHIC HAND Jiménez, Omar; Leija, Lorenzo; Muñoz, Roberto Centro de Investigación y de Estudios...weight and minimum consumption, minimum control and natural appearance. Keywords- Anthropomorphic, hand, Pneumatic system, Prosthesis 1 . INTRODUCTION...The projects have been guided through an specific line of development. The project MARCUS[ 1 ] includes easiness as the most important aspect what

Toward a Critique of the Information Age: Herbert Marcuse's Contribution to Information Science's Conceptions

ERIC Educational Resources Information Center

Cibangu, Sylvain K.

2013-01-01

Introduction: Just as we have created them, the new social media technologies have shaped every aspect of our societies. Meanwhile, information science has hardly addressed the ways in which these information technologies have shaped humans, and vice-versa. The major reason is the tendency and pressure to adjust (the needs of) humans to the ever…

Sequence to Sequence - Video to Text

DTIC Science & Technology

2015-12-11

Saenko, and S. Guadarrama. Generating natural-language video descriptions using text - mined knowledge. In AAAI, July 2013. 2 [20] P. Kuznetsova, V...Sequence to Sequence – Video to Text Subhashini Venugopalan1 Marcus Rohrbach2,4 Jeff Donahue2 Raymond Mooney1 Trevor Darrell2 Kate Saenko3...1. Introduction Describing visual content with natural language text has recently received increased interest, especially describing images with a

Validation of Brain Event-Related Potentials as Indicators of Cognitive Styles, Abilities, and Aptitudes.

DTIC Science & Technology

1983-02-01

1970; Callaway, 1973, 1975; Chalke & Ertl, 1965; Ertl, 1969; Ertl & Schafer, 1969; Galbraith, Gliddon, & Busk , 1970; Gucker, 1973; Marcus, 1970...related to intelligence--although not always (Bigum, Dustman, & Beck, 1970; Galbraith, Gliddon, & Busk , 1970; Perry, McCoy, Cunningham, Falgout...be directly related to intelligence--but not always (Bigum, Dustman, & Beck, 1970; Galbraith, Gliddon, & Busk , 1970; Perry, McCoy, Cunningham, Falgot

A Comparison of Intranasal and Oral Scopolamine for Motion Sickness Prevention in Military Personnel

DTIC Science & Technology

2008-08-18

Cornum, Caldwell & Cornum, 1997; Cowings et al., 1996; Golding & Stott, 1997; Marcus & Furman, 2006; Putcha, 1999; Wood & Graybiel, 1968). The most...performance effects (Lewandowski, Dietz, & Reeves, 1997; Elsmore, Reeves & Reeves, 2007; Kane , Roebuck-Spenser, Short, Kabat & Wilken, 2007; Wilken...Sullivan, Lewandowski & Kane , 2007). Visual acuity assessment An RAF rule (Neely, 1956) was used to measure visual accommodation (near-focus

An Examination of a Virtual Private Network Implementation to Support a Teleworking Initiative: The Marcus Food Company Inc. Case Study

ERIC Educational Resources Information Center

Ferguson, Jason W.

2010-01-01

In this dissertation, the author examined the capabilities of virtual private networks (VPNs) in supporting teleworking environments for small businesses in the food marketing sector. The goal of this research was to develop an implementation model for small businesses in the food marketing sector that use a VPN solution to support teleworker…

77 FR 4765 - Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-31

... to complete the abbreviated 2010 study. L-DEO plans to use one source vessel, the R/V Marcus G... will serve as a spare and will be turned on in case of failure of one of the other airguns. The... [email protected] . NMFS is not responsible for email comments sent to addresses other than the one...

Learning to Be Precarious--The Transition of Young People from School into Precarious Work in Germany

ERIC Educational Resources Information Center

Eckelt, Marcus; Schmidt, Guido

2015-01-01

The integration of young adults into the labor market is a challenge for every society. Because Germany survived the current crisis quite well and youth unemployment rate is more or less stable, the German apprenticeship-system, Duale Ausbildung, became a kind of new role model in Europe. In this article Marcus Eckelt and Guido Schmidt analyze the…

NEPC Review: "New York Charter Schools Outperform Traditional Selective Public Schools--More Evidence That Cream-Skimming Is Not Driving Charters' Success"

ERIC Educational Resources Information Center

Cordes, Sarah A.

2017-01-01

A common argument leveled against charter schools is that they attract the most motivated and intelligent students from already struggling public schools. Marcus Winters seeks to examine this claim, known as "cream-skimming," by comparing the performance of New York City's (NYC) charter middle schools with a set of traditional selective…

The Limits of Soviet Airpower: The Bear Versus the Mujahideen in Afghanistan, 1979-1989

DTIC Science & Technology

1997-06-01

satellite imagery identified Soviet TMS-65 decontamination vehicles and AGV-3 detox chambers in the vicinity of combat areas. In addition, the...Vladislav Tamarov, Afghanistan: Soviet Vietnam, trans. Naomi Marcus, Marianne Clarke Trangen, and Vladislav Tamarov (San Francisco: Mercury House...Tamarov. San Francisco: Mercury House, 1992. Turbiville, Graham. Ambush! The Road War in Afghanistan. Fort Leavenworth, KS: Soviet Army Studies Office

Scaling Bulk Data Analysis with Mapreduce

DTIC Science & Technology

2017-09-01

Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN COMPUTER SCIENCE from the NAVAL POSTGRADUATE SCHOOL September...2017 Approved by: Michael McCarrin Thesis Co-Advisor Marcus S. Stefanou Thesis Co-Advisor Peter J. Denning Chair, Department of Computer Science iii...98 xiii THIS PAGE INTENTIONALLY LEFT BLANK xiv List of Acronyms and Abbreviations CART Computer Analysis and Response Team DELV Distributed Environment

Stochastic Adaptive Estimation and Control.

DTIC Science & Technology

1994-10-26

Marcus, "Language Stability and Stabilizability of Discrete Event Dynamical Systems ," SIAM Journal on Control and Optimization, 31, September 1993...in the hierarchical control of flexible manufacturing systems ; in this problem, the model involves a hybrid process in continuous time whose state is...of the average cost control problem for discrete- time Markov processes. Our exposition covers from finite to Borel state and action spaces and

The galenic plague: a breakdown of the imperial pathocoenosis. Pathocoenosis and longue durée.

PubMed

Gourevitch, Danielle

2005-01-01

Is 'pathocoenosis', a notion conceived and a word coined by Mirko Grmek (1969), useful as far as ancient history is concerned? The author is interested in Galenic pathocoenosis, that of doctor Galen and his Emperor Marcus Aurelius (IInd cent. A.D.), when a new 'pestilence' or 'plague' (smallpox?) devastated the whole empire, from Mesopotamia to the Danube at least.

[The doctor and the consul. Relations between Galen and Flavius Boethos under Marcus Aurelius].

PubMed

Gourevitch, Danielle

2012-01-01

The author describes the rich relationship between young Galen, just arrived in Rome from his native Minor Asia, and Flavius Boethos a consul suffectus who was to become the governor of Syria, and asked him to cure his wife and then their son, Cyrillos. Although very famous, Galen who never became a Roman citizen, needed such a friend and social mentor.

Preventing Point-of-Sale System Intrusions

DTIC Science & Technology

2014-06-01

executives from Target and Nieman Marcus prepared written testimonials in advance of several congressional hearings on retail data breaches the week...of February 05, 2014 (Associated Press, 2014; United States Senate, 2014). While the Target data breach attracted significant national attention due...other parts of the world, and whether Congress should pass a federal data breach notification law that would require businesses to notify customers if

[Marcus Aurelius Antonius (121-180AD), philosopher and Roman emperor, and Galen's plague].

PubMed

Muñoz-Sanz, Agustín

2012-11-01

The study of the aetiologies of diseases in Ancient Times is usually a speculative intellectual exercise. When some authors attribute a specific aetiology to an old disease, there is a great risk of committing a methodological error, known as presentism by the modern historiography. The authority of the investigator, more than the weight of the scientific truth, is usually the reason why the diagnosis has remained over the years. The great epidemic of the years 164-165AD and afterwards, could have been smallpox (haemorrhagic form). Claude Galen, the famous doctor, described the symptoms in several books of his great Opera Omnia. For this reason, it is currently known among the scholars as Galen's plague. The epidemic was described for the first time in Seleucia (Mesopotamia). Until now, the actual geographic origin is unknown. We propose here that the beginning might be the kingdom of the old Han dynasty (now the Chinese Popular Republic). The epidemic swept the Roman Empire, from the east to the west, and from the southern to the northern borders. An immediate consequence of the infection was a high morbidity and mortality. In this sense, Galen's epidemic was one of the many factors that caused the fall and destruction of the Roman Empire. On the other hand, there is a general agreement among historians, biographers and researchers that the philosopher emperor Marcus Aurelius Antoninus (121-180AD was affected by the infection in the epidemic wave of 164-165AD. The death of Marcus Aurelius occurred on March 17 in the year 180AD, in Vindobonne, or perhaps Sirminium (near to Vienna). Many authors propose that the cause of the emperor's death was the same epidemic. We consider that it is not possible to demonstrate any of those speculative diagnoses. Finally, the epidemic of 189-190AD, that we have named of Commodus, was probably a different disease to the Galen's plague. There were several kinds of animals affected (anthropozoonoses). In this sense, this infection resembles more the previous Athens plague (430BC) or the epidemic of Justinian (552AD) than that of Galen's. Copyright © 2012 Elsevier España, S.L. All rights reserved.

Evaluating the sensory properties of unpolished Australian wild rice.

PubMed

Tikapunya, Tiparat; Henry, Robert J; Smyth, Heather

2018-01-01

Australian wild rices are genetically distinct from commercially cultivated rices and present new opportunities for the development of improved rice cultivars. Before use in rice breeding, the eating and cooking properties of Australian wild rice must first be understood as these are key factors in determining rice quality and consumer acceptance. Samples of Australian wild rice (taxa B) were collected and evaluated together with a commercial Canadian wild rice (Zizania aquatic L.), Oryza sativa L.cv. Nipponbare, and selected commercial rices including long grain, medium grain, basmati, red basmati, and red rice. Cooking profiles were established, physical traits were measured and conventional descriptive analysis techniques were used to compare the sensory properties of the unpolished rices. Twenty six descriptors, together with definitions, were developed with a panel of twelve experienced assessors including aroma, flavour, texture and aftertaste attributes. Results reveal that the Australian wild rice had a mild aroma and flavour similar to that of red rice and red basmati but without the lingering aftertaste. In terms of texture, the wild rice was firmer, and somewhat crunchy and chewy rather than soft and fluffy despite requiring a longer cooking time. The sensory, physical and cooking profiles indicate that Australian wild rice has a high potential for commercialization in itself and provides a suitable genetic source for breeding programs, particularly in the coloured rice market. Copyright © 2017 Elsevier Ltd. All rights reserved.

Asian wild rice is a hybrid swarm with extensive gene flow and feralization from domesticated rice

PubMed Central

Wang, Hongru; Vieira, Filipe G.; Crawford, Jacob E.; Chu, Chengcai; Nielsen, Rasmus

2017-01-01

The domestication history of rice remains controversial, with multiple studies reaching different conclusions regarding its origin(s). These studies have generally assumed that populations of living wild rice, O. rufipogon, are descendants of the ancestral population that gave rise to domesticated rice, but relatively little attention has been paid to the origins and history of wild rice itself. Here, we investigate the genetic ancestry of wild rice by analyzing a diverse panel of rice genomes consisting of 203 domesticated and 435 wild rice accessions. We show that most modern wild rice is heavily admixed with domesticated rice through both pollen- and seed-mediated gene flow. In fact, much presumed wild rice may simply represent different stages of feralized domesticated rice. In line with this hypothesis, many presumed wild rice varieties show remnants of the effects of selective sweeps in previously identified domestication genes, as well as evidence of recent selection in flowering genes possibly associated with the feralization process. Furthermore, there is a distinct geographical pattern of gene flow from aus, indica, and japonica varieties into colocated wild rice. We also show that admixture from aus and indica is more recent than gene flow from japonica, possibly consistent with an earlier spread of japonica varieties. We argue that wild rice populations should be considered a hybrid swarm, connected to domesticated rice by continuous and extensive gene flow. PMID:28385712

A theoretical study of three gas-phase reactions involving the production or loss of methane cations.

PubMed

Baptista, Leonardo; da Silveira, Enio F

2014-10-21

Hydrocarbon ions are important species in flames, spectroscopy and the interstellar medium. Their importance is reflected in the extensive body of literature on the structure and reactivity of carbocations. However, the geometry, electronic structure and reactivity of carbocations are difficult to assess. This study aims to contribute to the current knowledge of this subject by presenting a quantum mechanics description of methane cation dissociation using multiconfigurational methods. The geometric and electronic parameters of the minimum structure were determined for three main reaction paths: the dissociation CH4(+)→ CH2(+) + H2 and the dissociation-recombination processes CH4(+)↔ CH3(+) + H. The electronic and energetic effects of these reactions were analyzed, and it was found that each reaction path has a strong dependence on the methodology used as well as a strong multiconfigurational character during dissociation. The first doublet excited states are inner-shell excited states and may correspond to the ions that are expected to be formed after electron detachment. The rate coefficient for each reaction path was determined using variational transition state theory and RRKM/master equation calculations. The major dissociation paths, with their rate coefficients at the high-pressure limit, are CH4(+)(X(~)(2)B1) → CH3(+)(A(2)A1') + H((2)S) (k∞(T) = 1.42 × 10(+14) s(-1) exp(-37.12/RT)) and CH4(+)(X(~)(2)B1) → CH2(+)(A(2)A1) + H2((2)Σg(+)) (k∞(T) = 9.18 × 10(+14) s(-1) exp(-55.77/RT)). Our findings help to explain the abundance of ions formed from CH4 in the interstellar medium and to build models of chemical evolution.

Chemical dynamics simulations of X- + CH3Y → XCH3 + Y- gas-phase S(N)2 nucleophilic substitution reactions. Nonstatistical dynamics and nontraditional reaction mechanisms.

PubMed

Manikandan, Paranjothy; Zhang, Jiaxu; Hase, William L

2012-03-29

Extensive classical chemical dynamics simulations of gas-phase X(-) + CH(3)Y → XCH(3) + Y(-) S(N)2 nucleophilic substitution reactions are reviewed and discussed and compared with experimental measurements and predictions of theoretical models. The primary emphasis is on reactions for which X and Y are halogen atoms. Both reactions with the traditional potential energy surface (PES), which include pre- and postreaction potential energy minima and a central barrier, and reactions with nontraditional PESs are considered. These S(N)2 reactions exhibit important nonstatistical atomic-level dynamics. The X(-) + CH(3)Y → X(-)---CH(3)Y association rate constant is less than the capture model as a result of inefficient energy transfer from X(-)+ CH(3)Y relative translation to CH(3)Y rotation and vibration. There is weak coupling between the low-frequency intermolecular modes of the X(-)---CH(3)Y complex and higher frequency CH(3)Y intramolecular modes, resulting in non-RRKM kinetics for X(-)---CH(3)Y unimolecular decomposition. Recrossings of the [X--CH(3)--Y](-) central barrier is important. As a result of the above dynamics, the relative translational energy and temperature dependencies of the S(N)2 rate constants are not accurately given by statistical theory. The nonstatistical dynamics results in nonstatistical partitioning of the available energy to XCH(3) +Y(-) reaction products. Besides the indirect, complex forming atomic-level mechanism for the S(N)2 reaction, direct mechanisms promoted by X(-) + CH(3)Y relative translational or CH(3)Y vibrational excitation are possible, e.g., the roundabout mechanism.

Theoretical Study on the Dynamics of the Reaction of HNO((1)A') with HO2((2)A″).

PubMed

Mousavipour, S Hosein; Asemani, S Somayeh

2015-06-04

We used stochastic one-dimensional chemical master equation (CME) simulation to gain insight into the dynamics of the reaction of HNO((1)A') with HO2((2)A″). The reaction takes place over a multiwell, multichannel potential energy surface that is based on the computations at the CBS-QB3 level of theory. The calculated multipath potential energy surface consists of three potential wells and three van der Waals complexes. In solving the master equation, the Lennard-Jones potential is used to model the collision between the collider gases. The fractional population of different intermediates and products in the early stages of the reaction is examined to determine the role of the energized intermediates and van der Waals complexes on the kinetics of the title reaction. The major products of the title reaction at lower temperatures are OH, HNO2, HNOH, and O2(X(3)Σg(-)). The temperature- and pressure-dependence of the reaction over a wide range of temperature (300-3000 K) and pressure (0.1-2000 Torr) are studied. No sign of pressure dependence was being observed for the title reaction over the stated range of pressure. The calculated rate constants from the CME simulation are compared with those obtained from the RRKM-SSA method that is based on strong collision assumption. Our results indicate that the strong collision assumption increases the calculated rate constant for the formation of the main products (HNO2 + OH) by a factor of 2 at 300 K and 1 atm pressure, compared to the results of CME simulation, although the results are in good agreement at higher temperatures.

Theoretical study of the kinetics of reactions of the monohalogenated methanes with atomic chlorine.

PubMed

Brudnik, Katarzyna; Twarda, Maria; Sarzyński, Dariusz; Jodkowski, Jerzy T

2013-04-01

Ab initio calculations at the G2 level were used in a theoretical description of the kinetics and mechanism of the hydrogen abstraction reactions from fluoro-, chloro- and bromomethane by chlorine atoms. The profiles of the potential energy surfaces show that mechanism of the reactions under investigation is complex and consists of two - in the case of CH3F+Cl - and of three elementary steps for CH3Cl+Cl and CH3Br+Cl. The heights of the energy barrier related to the H-abstraction are of 8-10 kJ mol(-1), the lowest value corresponds to CH3Cl+Cl and the highest one to CH3F+Cl. The rate constants were calculated using the theoretical method based on the RRKM theory and the simplified version of the statistical adiabatic channel model. The kinetic equations derived in this study[Formula: see text]and[Formula: see text]allow a description of the kinetics of the reactions under investigation in the temperature range of 200-3000 K. The kinetics of reactions of the entirely deuterated reactants were also included in the kinetic analysis. Results of ab initio calculations show that D-abstraction process is related with the energy barrier of 5 kJ mol(-1) higher than the H-abstraction from the corresponding non-deuterated reactant molecule. The derived analytical equations for the reactions, CD3X+Cl, CH2X+HCl and CD2X+DCl (X = F, Cl and Br) are a substantial supplement of the kinetic data necessary for the description and modeling of the processes of importance in the atmospheric chemistry.

Mechanical and kinetic study on gas-phase formation of dinitro-naphthalene from 1- and 2-nitronaphthalene.

PubMed

Huang, Zixiao; Zhang, Qingzhu; Wang, Wenxing

2016-08-01

Nitrated polycyclic aromatic hydrocarbons have received an increasing number of considerations because of their higher mutagens than parent PAHs. In this paper, the formation of dinitro-naphthalene was investigated mechanistically using 1- and 2-nitronaphthalene as precursors with the aid of high-accuracy quantum chemistry calculation. The geometrical parameters, as well as vibrational frequencies, were calculated at the BB1K/6-31+G(d,p) level. Water molecule plays an important role in the formation of dinitro-naphthalene. The rate constants were deduced by canonical variational transition-state theory with small curvature tunneling contribution over the temperature range of 273-333 K. Meanwhile, the Arrhenius formulas were fitted for the OH addition of both 1- and 2-nitronaphthalene. The calculated overall rate constants for 1-nitronaphthalene and 2-nitronaphthalene at 298 K and 1 atm are 7.43 × 10(-13) and 7.48 × 10(-13) cm(3) molecule(-1) s(-1), respectively. The rate constants of NO3 addition to 1-nitronaphthalene and 2-nitronaphthalene by RRKM method at 298 K and 1 atm are 3.55 × 10(-15) and 3.47 × 10(-15) cm(3) molecule(-1) s(-1), respectively. This study provides a comprehensive investigation of the formation process of dinitro-naphthalenes, initiated by OH and NO3 radicals and should facilitate to illuminate its atmospheric source. Oxygen may probably be competitive with the second NO2 addition step when the concentration of NO2 is at low level. Copyright © 2016. Published by Elsevier Ltd.

Antioxidant activity of colored rice bran obtained at different milling yields.

PubMed

Fujita, Akiko; Fujitake, Hironori; Kawakami, Koji; Nomura, Masato

2010-01-01

In this study, we investigated the antioxidant components of three types of colored rice bran--forbidden rice, red rice and green rice--obtained from rice in which the pigment layer had been removed at milling yields of 90%-100% and 80%-90%. An evaluation of the effects of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity revealed that rice bran obtained from forbidden rice at milling yields of 90%-100% and 80%-90% and rice bran obtained from red rice at milling yields of 90%-100% showed favorable antioxidant activity. The antioxidant components were confirmed to be 3,4-dihydroxy methyl benzoate and p-methoxyphenol and they influence the antioxidant activity of the three types of colored rice bran.

Cytoplasmic-genetic male sterility gene provides direct evidence for some hybrid rice recently evolving into weedy rice

PubMed Central

Zhang, Jingxu; Lu, Zuomei; Dai, Weimin; Song, Xiaoling; Peng, Yufa; Valverde, Bernal E.; Qiang, Sheng

2015-01-01

Weedy rice infests paddy fields worldwide at an alarmingly increasing rate. There is substantial evidence indicating that many weedy rice forms originated from or are closely related to cultivated rice. There is suspicion that the outbreak of weedy rice in China may be related to widely grown hybrid rice due to its heterosis and the diversity of its progeny, but this notion remains unsupported by direct evidence. We screened weedy rice accessions by both genetic and molecular marker tests for the cytoplasmic male sterility (CMS) genes (Wild abortive, WA, and Boro type, BT) most widely used in the production of indica and japonica three-line hybrid rice as a diagnostic trait of direct parenthood. Sixteen weedy rice accessions of the 358 tested (4.5%) contained the CMS-WA gene; none contained the CMS-BT gene. These 16 accessions represent weedy rices recently evolved from maternal hybrid rice derivatives, given the primarily maternal inheritance of this trait. Our results provide key direct evidence that hybrid rice can be involved in the evolution of some weedy rice accessions, but is not a primary factor in the recent outbreak of weedy rice in China. PMID:26012494

Cytoplasmic-genetic male sterility gene provides direct evidence for some hybrid rice recently evolving into weedy rice.

PubMed

Zhang, Jingxu; Lu, Zuomei; Dai, Weimin; Song, Xiaoling; Peng, Yufa; Valverde, Bernal E; Qiang, Sheng

2015-05-27

Weedy rice infests paddy fields worldwide at an alarmingly increasing rate. There is substantial evidence indicating that many weedy rice forms originated from or are closely related to cultivated rice. There is suspicion that the outbreak of weedy rice in China may be related to widely grown hybrid rice due to its heterosis and the diversity of its progeny, but this notion remains unsupported by direct evidence. We screened weedy rice accessions by both genetic and molecular marker tests for the cytoplasmic male sterility (CMS) genes (Wild abortive, WA, and Boro type, BT) most widely used in the production of indica and japonica three-line hybrid rice as a diagnostic trait of direct parenthood. Sixteen weedy rice accessions of the 358 tested (4.5%) contained the CMS-WA gene; none contained the CMS-BT gene. These 16 accessions represent weedy rices recently evolved from maternal hybrid rice derivatives, given the primarily maternal inheritance of this trait. Our results provide key direct evidence that hybrid rice can be involved in the evolution of some weedy rice accessions, but is not a primary factor in the recent outbreak of weedy rice in China.

Rice production in relation to soil quality under different rice-based cropping systems

NASA Astrophysics Data System (ADS)

Tran Ba, Linh; Sleutel, Steven; Nguyen Van, Qui; Thi, Guong Vo; Le Van, Khoa; Cornelis, Wim

2016-04-01

Soil quality of shallow paddy soils may be improved by introducing upland crops and thus a more diverse crop cultivation pattern. Yet, the causal relationship between crop performance and enhanced soil traits in rice-upland crop rotations remains elusive. The objectives of this study were to (i) find correlations among soil properties under different rice-upland crop systems and link selected soil properties to rice growth and yield, (ii) present appropriate values of soil parameters for sustainable rice productivity in heavy clay soil, (iii) evaluate the effect of rotating rice with upland crops on rice yield and economic benefit in a long-term experiment. A rice-upland crop rotational field experiment in the Vietnamese Mekong delta was conducted for 10 years using a randomized complete block design with four treatments and four replications. Treatments were: (i) rice-rice-rice (control - conventional system as farmers' practice), (ii) rice-maize-rice, (iii) rice-mung bean-rice, and (iv) rice-mung bean-maize. Soil and plant sampling were performed after harvest of the rice crop at the end of the final winter-spring cropping season (i.e. year 10). Results show differences in rice growth and yield, and economic benefit as an effect of the crop rotation system. These differences were linked with changes in bulk density, soil porosity, soil aggregate stability index, soil penetration resistance, soil macro-porosity, soil organic carbon, acid hydrolysable soil C and soil nutrient elements, especially at soil depth of 20-30 cm. This is evidenced by the strong correlation (P < 0.01) between rice plant parameters, rice yield and soil properties such as bulk density, porosity, penetration resistance, soil organic carbon and Chydrolysable. It turned out that good rice root growth and rice yield corresponded to bulk density values lower than 1.3 Mg m-3, soil porosity higher than 50%, penetration resistance below 1.0 MPa, and soil organic carbon above 25 g kg-1. The optimal soil depth without restriction for rice root elongation was at least 25 cm from the soil surface. We suggest these values as indicative for optimal physical soil quality when growing rice in fine-textured alluvial soils and their definition as a first step towards presenting real threshold values.

Genetic diversity of weedy red rice (Oryza sativa) in Arkansas, USA

USDA-ARS?s Scientific Manuscript database

Weedy red rice (Oryza sativa L.) is a problematic weed in rice. About 50% of US rice is produced in Arkansas and 60% of these fields have some red rice infestation. Red rice populations are morphologically and phenologically diverse. We hypothesize that red rice in Arkansas has high genetic diversit...

Outcrossing Potential between U.S. Blackhull Red Rice and Indica Rice Cultivars

USDA-ARS?s Scientific Manuscript database

Weedy red rice is a major weed pest of rice in the southern U.S. Outcrossing between red rice and commercial tropical japonica rice cultivars has resulted in new weed biotypes that further hinder the effectiveness of weed management. In recent years, indica rice has been used increasingly as a ger...

An update on the use of rice in value-added food products.

USDA-ARS?s Scientific Manuscript database

Because of the huge quantity of rice produced annually, milled-rice co-products; such as, rice flour, rice bran, rice wax, and rice hull are plentiful and readily available. These co-products could be valuable sources of food ingredients, but they have been vastly under-utilized. This is a report ...

Storage stability of flour-blasted brown rice

USDA-ARS?s Scientific Manuscript database

Brown rice was blasted with rice flour rather than sand in a sand blaster to make microscopic nicks and cuts so that water can easily penetrate into the brown rice endosperm and cook the rice in a shorter time. The flour-blasted American Basmati brown rice, long grain brown rice, and parboiled long...