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  • 1
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A model is proposed which assumes that the pseudorotational potential in five-membered rings is given by the combination of contributions from the unsubstituted ring, from the individual substituents and from interactions between pairs of substituents. The application of this model to the potentials calculated by the MM2 force field for the cis and trans-2,5-dimethoxytetrahydrofuran shows that the contributions from the individual substituents explain the main features of the potentials of these disubstituted rings. The pseudorotational analysis from vicinal proton spin-spin coupling constants 3JHH confirms the realibility of the MM2 potentials.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 55-62 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The determination of minima and saddle points on the potential energy surfaces of the hydrogen bonded species O2-HF and O2-H2O is performed with unrestricted Hartree-Fock calculations. Geometries, electron density distributions, and relative energies for every stationary point are reported. Only one true minimum is found for O2-HF and for O2-H2O, and this approximately corresponds to a structure where the partially positive hydrogen atom is located along one of the superoxide ion electron lone-pair directions. Calculated ΔH, ΔS, and ΔG values for the reaction between O2- and H2O are in good agreement with experimental data.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 13 (1992), S. 1199-1209 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new formalism is presented, based upon the finite element method, that permits a dual representation of orbitals in terms of exponential or Gaussian functions as both an integral over the space of exponential parameters and as a linear combination of basis functions. The method has been implemented for the atomic Hartree-Fock problem using exponential functions and test calculations made for atoms ranging from B to Cl. Accurate and consistent results can be obtained for a variety of atoms in a simple way using computational schemes that are systematic and hierarchic in nature. The new formalism is promising for any method where the calculation of integrals is not a major problem, such as some approaches of the density functional method and the pseudospectral formulation of ab initio methods. © 1992 by John Wiley & Sons, Inc.
    Additional Material: 6 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 782-790 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have applied the FEM-MP2 method (an implementation of the p-version finite element technique within the framework of second-order Møller-Plesset perturbation theory, [J. Chem. Phys., 98, 5642 (1993), and references therein]) to calculate second-order correlation energies for the atoms Be, Ca, Sr, Ba, Yb, Cd, and Hg and thus to complete our studies on closed-shell elements. The FEM-MP2 method permits the use of virtual orbitals of very high angular momentum (lmax = 12) in combination with radial basis sets which are very close to completeness, in such a way that we are able to obtain results that could be the most accurate published so far and, in some cases, the only values available in the literature. We hope they may be useful as a reference for basis set saturation tests and for new methods to calculate correlation energies. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 10 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 183-189 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: In the forerunner of this article, we described a MNDO modification designed for studies of compounds with intramolecular O—H…O hydrogen bonds. Here, we report the further verification of the modification by means of its application to 14 compounds not considered in its development. Comparison of the calculated structural parameters and proton transfer characteristics with available experimental or ab initio results, and with those obtained using MNDO, AM1, MNDO/H, MNDO/M, and PM3, supports the validity of the new modification for prediction of hydrogen bond characteristics. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 887-895 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An equation is formulated on the basis of theoretical INDO/FPT calculations which describes the angular dependence of the propanic long-range coupling constant 4JMeH in substituted HCCCH3 fragments. This equation is a truncated Fourier series in the torsion angle φ, HCCMe, which takes into account the dependence of the Fourier coefficients on the bond angle θ, CCMe. The substituent effects are assumed to be additive. Some parameters in the equation may be obtained from the 4JMeH couplings in propane and neopentane derivatives. The calculated effect upon 4JMeH of changes in the bond angle θ is significant and it seems to be in part the cause of some effects which have been attributed to conformational dependence.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 13 (1992), S. 860-866 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Application of MNDO, AM1, PM3, MNDO/H, and MNDO/M methods to a set of compounds with intramolecular hydrogen bonds suggested that none of these methods accurately modeled the characteristics of the hydrogen bonds. Since the MNDO/H and MNDO/M methods work well for intermolecular hydrogen bonds, we followed their example and modified MNDO for intramolecular hydrogen bonds by altering the empirical core-core repulsion energy function for all pairs of atoms involved in intramolecular O-H—O bonds. The resulting modified method models the behavior of these bonds quite well, especially as regards their geometry and the barrier to proton transfer. © 1992 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 922-927 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A quantitative comparative analysis of molecular electrostatic potential (MEP) distributions generated from different wave functions was carried out. Wave functions were computed by using MNDO, AMl, STO-3G, 3-21G, 4-31G, 6-31G, 4-31G*, 6-31G*, and 6-31G** methods. Ten different compounds, which include usual atoms and groups of biomolecules, such as hydroxyl, carbonyl, amine, amide, imine, double and triple bonds, and heteroaromatic rings, were studied. For each compound, MEP values in the points of a common 3-D grid were computed; thereafter, the similarity between each pair of MEP distributions generated by different methods was assessed. Similarities were measured using the Spearman rank correlation coefficient. A similarity matrix was obtained for each compound. Similarity matrices were averaged and a hierarchical cluster analysis was carried out to classify the different quantum chemical methods. In the compounds studied, the main conclusion is the negligible difference between the pattern of MEP distributions generated from all split valence basis sets (with and without polarization functions). © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 9
    Publication Date: 2021-05-19
    Description: El presente proyecto se llevó a cabo en el puerto de Cartagena de Indias, Colombia, por la necesidad que tiene el país de reglamentar el Convenio Internacional 1973 para prevenir la contaminación pro buques y su protocolo de 1978 “MARPOL 73/78”, aprobado por el país mediante Ley 12 de 1981; asimismo, la Dirección General Marítima (DIMAR), de acuerdo con lo prescrito por el Decreto 2324/84, es la garante de la adecuada aplicación en Colombia de los convenios marítimos a los cuales se adhiere la nación. Durante 1992 se llevó a cabo la fase I en el puerto de Cartagena de Indias, el cual posee cerca de 53 muelles dedicados a diferentes actividades, de las cuales el 85% son de carácter privado y el 15 de carácter oficial. De estos, 19 deben cumplir con el Anexo I del Convenio MARPOL 73/78, pero sólo ECOPETROL Y CODI-MOBIL poseen infraestructura en tierra y servicios para recibir, tratar y eliminar residuos de los buques.
    Description: This study was undertaken in the port of Cartagena de Indias, Colombia, following the regulation established by the International Convention for the Prevention of Pollution at Sea and its Protocol MARPOL 73/78, ratified by the country through the Law 12 of 1981. The Dirección General Marítima (DIMAR), the Colombian Maritime Authority, according with the Decreto 2324 of 1984, is responsibles for the correct applications in Colombia of the internacional maritime agreements signed by the country. Phase I was accomplished during 1992 on the Port of Cartagena de Indias, where there are 53 piers dedicated to different activities, of which 85% are private, and the other 15% belong to the government. Of this, 19 must follow Annex 1 of MARPOL 73\78, but only ECOPETROL and CODI-MOBIL have the infrastructure in land to receieve, manipulate and eliminate residues from ships.
    Description: Published
    Keywords: Muelle. ; Puerto. ; Residuos. ; Buque ; ASFA_2015::C::Chemical oceanography ; ASFA_2015::H::Hydrology ; ASFA_2015::C::Contamination ; ASFA_2015::I::International relations
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: Pp.47-66
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  • 10
    Publication Date: 2021-05-19
    Description: In 1985 the CIOH started a program of marine pollution monitoring by oil in the Colombia Caribbean. With this project Colombia was integrated to the CARIPOL Program of IOCARIBE, which inputs information tu CARIPOL since march 1985. During 1985 the zone between punta Canoas and Barbacoas mas studied, where concentrations of disolved asid disperse hydrocarbons were detected, mainly in Cartagena bay with average values between 0.7 and 17.9 mg/L. The greater amount of these residues is attributed to maritime transportation, dock activity arad industrial uses.
    Description: En 1985 el CIOH inició el programa de “Vigilancia de la contaminación marina por residuos del petróleo en el Caribe colombiano”. Con este proyecto, se integró definitivamente Colombia al Programa CARIPOL de IOCARIBE, al cual se le aporta información desde marzo de ese año. Durante 1985 se ha estudiado la zona entre punta Canoas y punta Barbacoas, en donde se detectaron concentraciones de hidrocarburos disueltos y dispersos, principalmente en las estaciones situadas en el bahía de Cartagena; los valores promedio oscilan entre 0.7 y 17.9 ug/L. Se atribuye el mayor aporte de estos residuos al transporte marítimo, actividades de muelles y desembarcaderos, y usos industriales.
    Description: Published
    Keywords: Hidrocarburo ; Transporte marítimo ; ASFA_2015::C::Contamination ; ASFA_2015::C::Chemical oceanography
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: Pp.101-118
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