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  • 1
    Electronic Resource
    Electronic Resource
    Nonequilibrium solvation: An ab initio quantum-mechanical method in the continuum cavity model approximation (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 7375-7384 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electrostatic relationships necessary for the quantum-mechanical evaluation of the properties of a solute experiencing sudden changes in its internal charge distribution are here presented in a form suitable to perform accurate quantum-mechanical calculations of the solute properties. Attention has been paid to express the boundary conditions in the most convenient form and to avoid further constraints on the elaboration of the computational procedures. The approach exploits the separation of orientational (inertial) and electronic (inertialess) components of the polarization and complements the polarizable continuum method [Chem. Phys. 65, 239 (1982)], usually employed for static descriptions. Examples of application of the method to photoionization and electronic transitions processes are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464728
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  • 2
    Electronic Resource
    Electronic Resource
    Solvent effects on the potential energy surface of the 1:1 complex of water and formamide: Application of the polarizable continuum model to the study of nonadditive effects (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 5539-5546 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A study of the solvent effect on the potential energy surface of the 1:1 complex of water and formamide have been performed. In the description of the solvent we have employed the polarizable continuum model. The calculations were done at Hartree–Fock ab initio and Møller–Plesset (MP) levels. We found that the geometry of the system is appreciably modified by the solvent. The most important changes are the inversion of the water molecule orientation and the increase of the O(formamide)–H(water) distance by about 0.2 A(ring). In the gas phase binding to the carbonyl is energetically equivalent to binding to the amino group. However, in solution, water binds better to the carbonyl oxygen that to the NH group. The nonadditive contributions are, in general, important and can be related to the change in the monomer energies when one passes from the monomeric to the dimeric reaction potential. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471793
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  • 3
    Electronic Resource
    Electronic Resource
    Solvent Effects on Optical Emission and Absorption Spectra: Theoretical Calculation of the 1(n, .pi.) Transition of Formaldehyde in Solution (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 15758-15764 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100043a012
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  • 4
    Electronic Resource
    Electronic Resource
    A multiconfiguration self-consistent field/molecular dynamics study of the (n→π*)1 transition of carbonyl compounds in liquid water (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 6308-6315 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A model is presented for the electrostatic component of solvatochromic shifts in vertical electronic excitation energies. The model, which makes use of the mean-field approximation, combines quantum mechanics (QM) in the description of the solute molecule and molecular mechanics (MM) in the description of the solvent. The method is implemented at the multiconfigurational self-consistent field level. We present illustrative applications to the (n→π*)1 transitions of formaldehyde, acetaldehyde, and acetone in liquid water. The solvent shifts obtained compare well with other ab initio QM/MM calculations and when the electron correlation components are included with the experimental solvent shift, but differ from the results obtained with semiempirical QM/MM and continuum models. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1308283
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  • 5
    Electronic Resource
    Electronic Resource
    A theoretical study of liquid alcohols using averaged solvent electrostatic potentials obtained from molecular dynamics simulations: Methanol, ethanol and propanol (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 1613-1620 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We applied a quantum mechanics/molecular mechanics method that makes use of the mean field approximation to study the polarization of several alcohols in the liquid phase. The method is based on the calculation of the averaged solvent electrostatic potential from molecular dynamics data. Because of the reduced number of quantum calculations that our approximation involves, it permits the use of flexible basis sets, the consideration of the electron correlation and the solvent and solute polarization. We found that the molecules studied undergo strong polarization when they pass from the gas to the liquid phase. From this point of view, the polarization methanol displays a behavior lightly different from ethanol and propanol. The vaporization energies are very well reproduced especially when the correlation energy is included. The differences with the experimental values are less than 3% in the three systems studied. Finally, we consider the effect on the thermodynamics and the structure of the solution of the choice of the Lennard-Jones parameters. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1430253
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  • 6
    Electronic Resource
    Electronic Resource
    Induction of resistance in cocoa against Crinipellis perniciosa and Verticillium dahliae by acibenzolar- S-methyl (ASM) (2002)
    Oxford, UK : Blackwell Science Ltd
    Plant pathology 51 (2002), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The benzothiadiazole compound acibenzolar-S-methyl (ASM) was assessed as an inducer of resistance against Crinipellis perniciosa, agent of witches’ broom, and Verticillium dahliae, agent of vascular wilt, both on cocoa. ASM induced a reduction in incidence of witches’ broom of up to 84·5% when sprayed 30 days before inoculation on cocoa seedlings of cv. Catongo. ASM also induced a reduction in severity of Verticillium wilt to 55·4% on cv. Theobahia. For both pathosystems, effects of dose on disease were not clearly observed. The efficacy of the inducer increased with the interval between sprayings and the respective inoculations with the pathogens. In another experiment, the effect of ASM on the control of witches’ broom on cocoa seedlings was compared with that of cuprous oxide and tebuconazole, all sprayed 15 days before inoculation. ASM reduced disease incidence by 60·1% compared with the inoculated control. ASM was superior to tebuconazole, and there was also a tendency for ASM to be better than cuprous oxide. To understand the mechanism of action of ASM as an inducer of resistance, alterations in the levels of total phenolics, polyphenol oxidases and peroxidases were evaluated 3, 15 and 30 days after spraying of seedlings of cv. Catongo. Enzyme activities from seedlings of cv. Theobahia were evaluated 30 days after spraying. On cv. Catongo, no significant differences in total phenolic content and polyphenol oxidase activity were detected after spraying. However, an increase in peroxidase activity was detected at all times of evaluation. On cv. Theobahia, significant increases in activities of peroxidase and polyphenol oxidase were detected, indicating that defence responses due to ASM were dependent on host genotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3059.2002.00754.x
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of dopamine D2 and D3 antagonists on spontaneous motor activity and morphine-induced hyperactivity in male mice (1999)
    Springer
    Psychopharmacology 143 (1999), S. 82-88 
    Details
    ISSN: 1432-2072
    Keywords: Key words U-99194A-maleate ; Morphine ; Haloperidol ; Sulpiride ; Motor activity ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: Dopaminergic neurotransmission, in particular the mesolimbic pathway, is involved in spontaneous locomotor activity and in morphine-induced hyperactivity, since the drugs acting on DA receptors can modify the action of morphine and this effect could be dependent on the type of DA receptor affected. Objective: In this study, the action of U-99194A maleate, haloperidol, sulpiride and morphine (5, 10, 20, 40 mg/kg) on locomotor activity in male mice was evaluated. Likewise, the effects of these dopaminergic antagonists on morphine-induced hyperactivity were studied. Methods: Animals treated with U-99194A maleate (2.5, 5, 10, 20 mg/kg), haloperidol (0.075, 0.1 mg/kg), sulpiride (20, 40 mg/kg), or morphine (5, 10, 20, 40 mg/kg), and animals treated with these neuroleptics plus morphine were tested in an actimetre at different time points. Results: It was found that an increase in locomotor activity was produced between 0 and 30 min after the administration of 20 mg/kg U-99194A maleate and between 30 and 60 min after the administration of 20 and 40 mg/kg morphine. This dose of U-99194A maleate and the high dose of sulpiride reverts the hyperactivity induced by 20 mg/kg morphine. Haloperidol reversed the hyperactivity induced by all doses of morphine. Conclusions: Our results confirm that the action of DA D2 and D3 receptors could be dependent on the dopaminergic state, in this case modified by the action of morphine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050922
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  • 8
    Electronic Resource
    Electronic Resource
    SiOxNy Films deposited with SiCl4 by remote plasma enhanced CVD (1999)
    Springer
    Journal of materials science 34 (1999), S. 3007-3012 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Silicon oxynitride films have been deposited with SiCl4 by remote-plasma enhanced chemical vapor deposition (PECVD) at a substrate temperature of 250°C. Different mixtures of O2 and NH3 were used to obtain different oxynitride compositions ranging from SiO2 to an stoichiometry close to that of silicon nitride. Rutherford backscattering spectrometry was used to determine the chemical composition of the SiOxNy films. The behavior of the IR absorption spectra as well as the refractive index measured by ellipsometry were used to estimate the effect of the different deposition parameters. It was found that the IR spectra show a shift of the characteristic peak associated with the stretching vibration mode of the Si-O-Si bonds towards lower wavenumbers as the relative concentration of ammonia was increased with respect oxygen. No double peaks associated with silicon oxide and silicon nitride were observed, indicating the formation of an homogeneous alloy. The IR spectra did not show any presence of water or hydrogen related impurities in the film. Also the effect of a hydrogen flow added during the deposition process on the structural characteristics of the deposited films was studied using dielectric spectroscopy and atomic force microscopy measurements showing that the hydrogen flow added during deposition results in a reduction of the film roughness and a planarization effect, which is very interesting for the application of these films in microelectronics devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004620409994
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  • 9
    Electronic Resource
    Electronic Resource
    Naturalness of the space of states in quantum mechanics (1997)
    Springer
    International journal of theoretical physics 36 (1997), S. 883-921 
    Details
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We show how certain constructions of quantum mechanics, like monopoles, instantons, and the Schrödinger-von Neumann equation, are related to geometric functors which are representable. We study the differential geometry of the projective bundle associated with an infinite-dimensional separable Hilbert space, and we construct a universal connection which, is described as a subspace of skwe-Hermitian operators. This connection is responsible for the Berry phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02435791
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  • 10
    Electronic Resource
    Electronic Resource
    Topology of the Symmetry Group of the Standard Model (1999)
    Springer
    International journal of theoretical physics 38 (1999), S. 2485-2509 
    Details
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the topological structure of thesymmetry group of the standard model, GSM =U(1) × SU(2) × SU(3). Locally,GSM ≃ S1 ×(S3)2 × S5. For SU(3), whichis an S3-bundle over S5 (and therefore a local product of thesespheres) we give a canonical gauge i.e., a canonical setof local trivializations. These formulas give explicitlythe matrices of SU(3) without using the Lie algebra (Gell-Mann matrices). Globally, we prove thatthe characteristic function of SU(3) is the suspensionof the Hopf map $$s^3 \underrightarrow hs^2$$ . We also study the case of SU(n) forarbitrary n, in particular the cases of SU(4), a flavor group, and of SU(5),a candidate group for grand unification. We show thatthe 2-sphere is also related to the fundamentalsymmetries of nature due to its relation to SO0(3, 1), the identity component of the Lorentz group, asubgroup of the symmetry group of several gauge theoriesof gravity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026649024484
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