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  • 1
    Electronic Resource
    Electronic Resource
    Sonicated X-ray contrast agents for quantitative myocardial contrast echocardiography — a critical approach (1995)
    Springer
    Heart and vessels 10 (1995), S. 96-105 
    Details
    ISSN: 1615-2573
    Keywords: Non-ionic radiographic contrast agent ; Sonication ; Microbubbles ; Backscatter intensity ; Quantitative myocardial blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Contrast echocardiography with sonicated radiographic contrast agents has been used for the qualitative and quantitative determination of myocardial blood flow. One major problem has been the size of the microbubbles since only bubbles smaller than 8 µm are expected to pass the capillary bed and larger bubbles may obstruct the capillaries and, thus, alter myocardial blood flow. These techniques have been used for several years, but their reliability has not yet been assessed accurately. Five different methods for the production of sonicated radiographic contrast agents (methods 1–3 from the literature, and 4 and 5 from our laboratory; M1–5) were evaluated for their use in quantitative contrast echocardiography. The sonication of non-ionic X-ray contrast media was performed with a standard titanium probe (20 kHz) for methods 1–4, with variation in the sonication time and the number of sonication jets used for each method. In M5, we used bubbles that were produced by the insufflation of oxygen in the X-ray contrast agent; large (〉8 µm) bubbles were destroyed by sonication at 380kHz (resonance method). Mean bubble size was determined by computerized videomicroscopy. The effect of bubble size on the backscatter of the ultrasonic signal was calculated for each method. Mean bubble size (±1 SD) ranged between 11.5 ± 4µm and 16.1 ± 14 µm for M1–M5. The best values, i.e., the smallest bubbles, were found with M4 (prepressurized contrast medium). Assuming capillary passage for bubbles smaller than 8 µm, only 14%–48% of the bubbles were smaller than 8 µm (M1–M5). The best results with regard to bubble size (≤8 µm) were observed with M5 (48% ≤8 µm). In regard to the influence of bubble size on the backscatter of the ultrasonic signal, 56%–98.5% of the signal was produced by bubbles larger than 15 µm (M1–5) but the best results were obtained with M4. It is concluded that capillary-passage of sonicated microbubbles (≤8 µm) can be expected in only 14%–48% of the bubbles for the five different sonication techniques. More than 50% of all microbubbles produced by these techniques are larger than the expected 8 µm. These large bubbles are responsible for the backscatter of the ultrasonic signal in the vast majority of cases. Thus, the sonication of radiographic contrast agents appears to be inappropriate for the production of uniformly small microbubbles and, thus, this method is not suitable for quantitative measurements of coronary blood flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01744500
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  • 2
    Electronic Resource
    Electronic Resource
    Spin projected EHF method: Calculations for a four-electron model system (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 363-372 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spin projected extended Hartree-Fock equations for successive optimization of the orbitals are derived for the four-electron case and applied to butadiene in the PPP approximation. The method shows an excellent convergence and gives 91.4% of the correlation energy for the given model-Hamiltonian.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080305
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  • 3
    Electronic Resource
    Electronic Resource
    Spin-projected EHF method. II. The equations for successive optimization of the orbitals in the many-electron case (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 9 (1975), S. 517-526 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extended Hartree-Fock equations of the spin-projected scheme are derived in a form suitable for the construction of a surely convergent method of solution using successive optimization of the individual orbitals. The derivation is based on a specific form of the generalized Brillouin theorem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560090314
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  • 4
    Electronic Resource
    Electronic Resource
    Bond order and valence: Relations to Mulliken's population analysis (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 419-419 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560280309
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  • 5
    Electronic Resource
    Electronic Resource
    Bond orders and valences from ab initio wave functions (1986)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 29 (1986), S. 477-483 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The definition and properties of the bond order and valence indices calculated from ab initio wave functions are summarized. Their physical interpretation relationships to the exchange effects in bonding and generalization to correlated wave functions are also discussed. Some examples with typical bond order and valence values are shown.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560290320
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  • 6
    Electronic Resource
    Electronic Resource
    Spin-Projected extended Hartree-Fock equations. II. Odd-electron systems (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 893-899 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spin-projected extended Hartree-Fock equations discussed in Part I for an even number of electrons are given here for the odd-electron case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080605
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  • 7
    Electronic Resource
    Electronic Resource
    Erratum (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 9 (1975), S. 555-555 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560090318
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  • 8
    Electronic Resource
    Electronic Resource
    A comparison of different DODS methods when the number of electrons increases (1976)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 10 (1976), S. 961-966 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have performed RHF, UHF, UHF with subsequent spin projection, and EHF calculations for the π-electrons of some polyene chains of different lengths in order to investigate the relations among these methods when the number of electrons increases. Special attention is paid to the importance of spin projection for different energetic quantities.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560100606
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  • 9
    Electronic Resource
    Electronic Resource
    EHF Description of superexchange: Relations to Anderson's model (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 783-796 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the treatment of the superexchange in insulators, based on the spin projected extended Hartree-Fock (EHF) method may be considered as a direct generalization of Anderson's ligand field (or kinetic exchange) theory: the EHF methods permits to construct explicitly the effective orbitals for the magnetic electrons and to determine all the parameters occurring in Anderson's theory from only one variational problem.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180312
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  • 10
    Electronic Resource
    Electronic Resource
    Towards a “Chemical” Hamiltonian (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 23 (1983), S. 341-363 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analysis of the LCAO Hamiltonian is performed in terms of a “mixed” formulation of the second quantization for nonorthogonal orbitals, compressing the different interactions to one- and two-center terms as far as possible by performing appropriate projections. For this purpose an operator of atomic charge is also introduced, the expectation values of which are the Mulliken gross atomic populations on the individual atoms. The LCAO Hamiltonian is decomposed into terms having different physical meaning and significance: (i) sum of effective atomic Hamiltonians; (ii) the electrostatic interactions in the point-charge approximation; (iii) the electrostatic effects connected with the deviation of the actual charge distribution from the pointlike one; (iv) two-center overlap effects; (v) finite basis (“counterpoise”) correction terms related to the individual atoms; and (vi) similar finite basis correction terms with respect to the two-center interactions. Only terms of types (i) to (iv), containing no three- or four-center integrals, are considered as having physical significance. Based on the analysis of the Hamiltonian, an energy partitioning scheme is developed, and explicit expressions are given for one- and two-center (and basis extension) components of the SCF energy. The approach is also applied to the problem of intermolecular interactions, and an explicit formula is given permitting calculation of the “counterpoise” part of the supermolecule energy by properly taking into account that it depends not only on the extension of the basis, but also on the occupation of the additional orbitals in the intervening molecule - a factor completely overlooked in the usual scheme of calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560230203
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