Correlation analysis of the structures and gas-liquid chromatographic retention indices of amines

Quantitative structure-retention relationship(QSRR) was studied for amines to gas-liquid chromatography on three stationary phases of different polarities with the topological indices A(m) (A(m1), A(m2), A(m3)) and gravitational index GI. The algorithm of "Leaps and Bounds" was performed for selection of the variables. And the multi-regression and the quasi-Newton neural networks were employed for the calculation with better results.

Structure-activity relationships for antiplasmodial activity among aminoquinolines

The extended gravitational index G(Q) and quantum-chemical descriptors were calculated for the relationship analysis of aminoquinolines. An evolutionary algorithm was described for variable selection and building QSAR models. And the quasi-newton neural networks were employed with better results.

Kinetic isotope effects of proton transfer reaction for amines by ultrasonic relaxation methods: Unexpected evidence from the results in ethylamine solutions

Ultrasonic absorption coefficients for ethylamine in heavy water (D2O) and in light water (H2O) have been measured in the frequency range from 0.8 to 220 MHz at 25 degrees C. A single relaxational process has been observed in these two kinds of solutions. From the concentration dependence of the ultrasonic relaxation parameters, and following the reaction mechanism proposed by Eigen et al. for ethylamine in H2O, the causes of the relaxations have been attributed to a perturbation of an equilibrium associated with a deuteron or proton transfer reaction. The rate and equilibrium constants have been estimated from deuterioxide or hydroxide ion concentration dependence of the relaxation frequency, and the kinetic isotope effects have been determined. In addition, the standard volume changes of the reactions have been calculated from the concentration dependence of the maximum absorption per wavelength, and the adiabatic compressibility has also been determined from the density and sound velocity for ethylamine in D2O and in H2O, respectively. These results are compared with those for propylamine and butylamine and are discussed in relation to the different kinetic properties between D2O and H2O, the reaction radii derived by Debye theory, and the structural properties of the reaction intermediate.

Calculations of cross sections of resonant two-photon transitions to the second excited 4f5d state in Pr3+: Y3Al5O12 using density matrix theory

The density matrix resonant two-photon absorption (TPA) theory applicable to laser crystals doped with rare earth ions is described. Using this theory, resonant TPA cross sections for transitions from the ground state to the second excited state of the 4f5d configuration in cm(4)s Pr3+:Y3Al5O12 are calculated. The peak value of TPA cross section calculated is 2.75 x 10(-50) cm(4)s which is very close to the previous experimental value 4 x 10(-50) cm(4) s. The good agreement of calculated data with measured values demonstrates that the density matrix resonant TPA theory can predict resonant TPA intensity much better than the standard second-order perturbation TPA theory.

Ultrasonic relaxation kinetics on fast deuteron transfer reaction

Propylamine has been selected to investigate the isotope effect of a fast deuteron transfer reaction by ultrasonic relaxation method. Ultrasonic absorption coefficients of propylamine in heavy water (D2O) at 25 degrees C in the concentration range from 0.0107 to 0.6300 mol dm(-3) have been measured by pulse and resonance methods over the frequency range from 0.8 to 220 MHz. A Debye-type single relaxation absorption has been observed in the solution. From the dependence of the ultrasonic relaxation parameters on the concentration and solution pH, the source of the observed relaxation has been attributed to a perturbation of the chemical equilibrium associated with the deuteron transfer reaction. The rate and equilibrium constants have been determined by the measurement of the deuteroxyl ion concentration dependence of the relaxation frequency. Also the standard volume change of the reaction has been determined from the concentration dependence of the maximum absorption per wavelength and the adiabatic compressibility has been calculated from the density and the sound velocity in the solution. These results have then been compared with those obtained for propylamine in light water (H2O). The forward rate constant is greater and the reverse rate constant is smaller in DO than in H2O. The standard volume change for deuteron transfer is greater than that for proton transfer reaction, and the adiabatic compressibility shows a similar trend. These data support an argument that there exists a stronger hydrogen bond in D2O than in H2O. The difference of the stability in the intermediate states, R-ND3+... OD- and R-NH3+... OH-, has also been considered from the results of the isotope effects.

Structures and vibrational spectra of C-2 and LaC2+ clusters

C-2 and LaC2+ were studied using Hartree-Fock(HF), B3LYP (Becke 3-paremeter-Lee-Yang-Parr) density functional method, second-order Moller-Plesset perturbation (MP2) and coupled cluster singles and doubles with non-iterative triples(CCSD(T)) methods. The basis set employed was LANL1DZ. Geometries, vibrational frequencies and other quantities were reported. The results showed that for C-2, all the methods performed well for low spin state (singlet), while only HF and B3LYP remained so for high spin state (triplet). For LaC2+, four isomers were presented and fully optimized. The results suggested that linear isomers with C-infinity v and D-infinity h symmetries were predicted to be saddle points on the energy surface for all the methods, while for isomers with C-2 upsilon and C-s symmetries, they were local minima except C-2 upsilon at B3LYP level, and were isoenergetic at HF, MP2 and CCSD(T) levels, near isoenergetic at B3LYP level. From the differences between HOMO and LUMO, it is also known that the isomers with C-2 upsilon and C-s symmetries offer the largest values and therefore correspond to the most stable structure. For La-C bond lengths, B3LYP gives the shortest, the order is B3LYP

Propagators and ridge jumps in a back-arc basin, the West Philippine Basin

We explore the tectono-magmatic processes in the western West Philippine Basin, Philippine Sea Plate, using bathymetric data acquired in 2003 and 2004. The northwestern part of the basin formed through a series of northwestward propagating rifts. We identify at least five sequences of propagating rifts, probably triggered by mantle flow away from the mantle thermal anomaly that is responsible for the origin of the Benham and Urdenata plateaus. Gravitational forces caused by along-axis topographic gradient and a similar to 30 degrees ridge reorientation appear to also be driving the rift propagations. The along-axis mantle flow appears to be reduced and deflected along the Luzon-Okinawa fracture zone, because the spreading system remained stable west of this major fault zone. North-east of the Benham plateau, a left-lateral fracture zone has turned into a NE-SW-trending spreading axis. As a result, a microplate developed at the triple junction.

Tectonic and geodynamic pattern of marginal seas on the West Pacific inferred from multi-satellite altewetry geoid

With the rapid development of satellite observations, we can use the altimetry geoid to study submarine tectonics and geodynamics. On the basis of the 4' x 4' geoid undulation calculated from altimeter data of Geosat, ERS-1/2 and Topex/Poseidon on the West Pacific, located between 0degreesN similar to 45degreesN, 100degreesC similar to 150degreesE, Bouguer, Glenni and isostatic geoid undulation are obtained from correction of gravitational potential of the global topography and isostacy. Moho discontinuity depth is inversed by the Glenni geoid undulation, and the stress field from small-scale mantle convection is reasonably calculated from the isostatic geoid undulation. The results show that within the Philippine Sea and the South China Sea, short-wavelength lineations of the geoid undulation are parallel or cross to magnetic lineations and rifting ridges. The Moho depth of marginal sea basins becomes shallow southward, and its values are similar to that of the Philippine Sea. These facts show that strength of tectonic activities are almost the same on the both sides of the Ryukyu-Taiwan-Philippine are. Various kinds of tectonic features with different driving mechanisms of small-middle and large-scale of mantle convection, however, display a special pattern of tectonics and geodynamics of the continental marginal seas distinguished from oceans and continents.

Effective response of nonlinear composite under external AC and DC electric field

A perturbation method is used to study effective response of nonlinear Kerr composites, which are subject to the constitutive relation of electric displacement and electric field, D-alpha = epsilon(alpha)E + chi(alpha)vertical bar E vertical bar(2)E. Under the external AC and DC electric field E-app = E-a (1 + sinwt), the effective nonlinear responses and local potentials are induced by the cubic nonlinearity of Kerr materials at all harmonics. As an example in three dimensions, we have investigated this kind of nonlinear composites with spherical inclusions embedded in a host. At all harmonic frequencies, the potentials in inclusion and host regions are derived. Furthermore, the formulae of the effective linear and nonlinear responses are given in the dilute limit.

Dynamics of nonlinear error growth and season-dependent predictability of El Nino events in the Zebiak-Cane model

With the intermediate-complexity Zebiak-Cane model, we investigate the 'spring predictability barrier' (SPB) problem for El Nino events by tracing the evolution of conditional nonlinear optimal perturbation (CNOP), where CNOP is superimposed on the El Nino events and acts as the initial error with the biggest negative effect on the El Nino prediction. We show that the evolution of CNOP-type errors has obvious seasonal dependence and yields a significant SPB, with the most severe occurring in predictions made before the boreal spring in the growth phase of El Nino. The CNOP-type errors can be classified into two types: one possessing a sea-surface-temperature anomaly pattern with negative anomalies in the equatorial central-western Pacific, positive anomalies in the equatorial eastern Pacific, and a thermocline depth anomaly pattern with positive anomalies along the Equator, and another with patterns almost opposite to those of the former type. In predictions through the spring in the growth phase of El Nino, the initial error with the worst effect on the prediction tends to be the latter type of CNOP error, whereas in predictions through the spring in the decaying phase, the initial error with the biggest negative effect on the prediction is inclined to be the former type of CNOP error. Although the linear singular vector (LSV)-type errors also have patterns similar to the CNOP-type errors, they cover a more localized area than the CNOP-type errors and cause a much smaller prediction error, yielding a less significant SPB. Random errors in the initial conditions are also superimposed on El Nino events to investigate the SPB. We find that, whenever the predictions start, the random errors neither exhibit an obvious season-dependent evolution nor yield a large prediction error, and thus may not be responsible for the SPB phenomenon for El Nino events. These results suggest that the occurrence of the SPB is closely related to particular initial error patterns. The two kinds of CNOP-type error are most likely to cause a significant SPB. They have opposite signs and, consequently, opposite growth behaviours, a result which may demonstrate two dynamical mechanisms of error growth related to SPB: in one case, the errors grow in a manner similar to El Nino; in the other, the errors develop with a tendency opposite to El Nino. The two types of CNOP error may be most likely to provide the information regarding the 'sensitive area' of El Nino-Southern Oscillation (ENSO) predictions. If these types of initial error exist in realistic ENSO predictions and if a target method or a data assimilation approach can filter them, the ENSO forecast skill may be improved. Copyright (C) 2009 Royal Meteorological Society

Effective nonlinear AC response to composite with spherical particles

An effective nonlinear alternative-current (AC) response to granular nonlinear-composite with spherical inclusions embedded in a host medium under the action of an external AC field is investigated by using a perturbation approach. The local potentials of composite at higher harmonics are derived both in a region of local inclusion particles and in a local host region under the action of a sinusoidal field E-1 sin ω t + E-3 sin 3ω t. An effective nonlinear-response to composite and the relationship between the effective nonlinear-responses at the fundamental frequency and the third harmonics are also studied for the spherical inclusions in a dilute limit.

Second-order Stokes solutions for internal waves in three-layer density-stratified fluid

In this paper, internal waves in three-layer stratified fluid are investigated by using a perturbation method, and the second-order asymptotic solutions of the velocity potentials and the second-order Stokes solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the first-order solutions are consistent with ordinary linear theoretical results, and the second-order solutions describe the second-order modification on the linear theory and the interactions between the two interfacial waves. Both the first-order and second-order solutions derived depend on the depths and densities of the three-layer fluid. It is also noted that the solutions obtained from the present work include the theoretical results derived by Umeyama as special cases.

Representation of microscale ocean wavenumber spectrum correct to the second order

In this paper, the analytical representations of four wave source functions in high-frequency spectrum range are given on the basis of ocean wave theory and dimensional analysis, and the perturbation method is used to solve the governing equations of ocean wave high-frequency spectrum on the basis of the temporally stationary and locally homogeneous scale relations of microscale wave. The microscale ocean wavenumber spectrum correct to the second order has an explicit structure, its first order part represents the equilibrium between different source functions, and its second order part represents the contribution of microscale wave propagation.

Effective AC response of nonlinear spherical coated composites

Under alternating current electric field, effective response of granular nonlinear composites with spherical coated inclusions is investigated in the dilute limit by using the perturbation approach. For an external sinusoidal applied field with finite frequency omega, the local fields and potentials of composites in general consist of components at all harmonics for cubic nonlinear constitutive relationships. We derive the local potentials of spherical coated composites at harmonics. Moreover, we give the formulae of the nonlinear effective AC susceptibility at the third harmonic frequency.

A theory of nonlinear AC response in coated composites

A method for determining effective dielectric responses of Kerr-like coated nonlinear composites under the alternating current (AC) electric field is proposed by using perturbation approach. As an example, we have investigated the composite with coated cylindrical inclusions randomly embedded in a host under an external sinusoidal field with finite frequency omega. The local field and potential of composites in general consists of components with all harmonic frequencies. The effective nonlinear AC responses at all harmonics are induced by the coated nonlinear composites because of the nonlinear constitutive relation. Moreover, we have derived the formulae of effective nonlinear AC responses at the fundamental frequency and the third harmonic in the dilute limit.