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  • Articles  (805)
  • Chemistry and Pharmacology  (805)
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  • Articles  (805)
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  • 1
    Electronic Resource
    Electronic Resource
    On the Munn–Silbey approach to nonlocal exciton–phonon coupling (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2335-2345 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A canonical transformation method originally proposed by Munn and Silbey is used to partially diagonalize a model Hamiltonian which incorporates both local and nonlocal exciton–phonon coupling. At the heart of the method is a secular elimination principle which poses a difficult self-consistency problem. A limited form of this self-consistency problem was solved in an approximate fashion by primarily analytical methods in the original work of Munn and Silbey. We take a numerical approach, solving the general self-consistency problem to desired accuracy. Among the differences between our findings and those of the original work are polaron binding energies much larger and Debye–Waller factors much smaller than originally anticipated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466480
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  • 2
    Electronic Resource
    Electronic Resource
    Reduced density matrix and combined dynamics of electrons and nuclei (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4016-4027 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nuclear dynamics is incorporated into an efficient density matrix formalism of electronic dynamics which has been applied to molecular systems containing thousands of atoms. The formalism for the combined dynamics of electrons and nuclei is derived from the Dirac–Frenkel variational principle. The single electron reduced density matrices and the Glauber coherent states are used for the electronic and nuclear degrees of freedom, respectively. The new formalism is applicable to simulate the dynamics of large molecular systems. As an illustration of its validity, the formalism is employed to calculate the electron and nuclei dynamics of hydrogen molecules. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288374
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  • 3
    Electronic Resource
    Electronic Resource
    Dependence of C60 Formation on Orientation of Graphite Lattice Plane (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 13440-13442 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100102a002
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  • 4
    Electronic Resource
    Electronic Resource
    Variational energy band theory for polarons: Mapping polaron structure with the Toyozawa method (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 3159-3178 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this article we revisit from a contemporary perspective a classic problem of polaron theory in one space dimension following the variational approach originally taken by Toyozawa. Polaron structure is represented by variational surfaces giving the optimal values of the complete set of exciton and phonon amplitudes for every value of the joint exciton-phonon crystal momentum κ. Through this exfoliation of the exciton-phonon correlations comprising the polaron, characteristic small polaron, large polaron, and nearly free phonon structures are identified, and the manner in which these compete and/or coexist is examined in detail. Through such examination, the parameter space of the problem is mapped, with particular attention given to problematic areas such as the highly quantum mechanical weak-coupling regime, the highly nonlinear intermediate-coupling regime, and to the self-trapping transition that may be said to mark the onset of the strong-coupling regime. Through such examination of the complete parameter space at all κ, it is found that the common notion of a self-trapping phenomenon associated with κ=0 is a limiting aspect of a more general finite-κ phenomenon. Quantities such as phonon number distributions, complete ground state energy bands, and effective masses are obtained for all κ. The inverse problem of associating localized functions with the variational energy bands is addressed, with attention given to the concept of solitons and with the explicit construction of polaron Wannier states. The successes and failures of the Toyozawa method are assessed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474667
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  • 5
    Electronic Resource
    Electronic Resource
    A variational approach to nonlocal exciton–phonon coupling (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2728-2740 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we apply variational energy band theory to a form of the Holstein Hamiltonian in which the influence of lattice vibrations (optical phonons) on both local site energies (local coupling) and transfers of electronic excitations between neighboring sites (nonlocal coupling) is taken into account. A flexible spanning set of orthonormal eigenfunctions of the joint exciton–phonon crystal momentum is used to arrive at a variational estimate (bound) of the ground state energy for every value of the joint crystal momentum, yielding a variational estimate of the lowest polaron energy band across the entire Brillouin zone, as well as the complete set of polaron Bloch functions associated with this band. The variation is implemented numerically, avoiding restrictive assumptions that have limited the scope of previous assaults on the same and similar problems. Polaron energy bands and the structure of the associated Bloch states are studied at general points in the three-dimensional parameter space of the model Hamiltonian (electronic tunneling, local coupling, nonlocal coupling), though our principal emphasis lies in the understudied area of nonlocal coupling and its interplay with electronic tunneling; a phase diagram summarizing the latter is presented. The common notion of a "self-trapping transition'' is addressed and generalized. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473793
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  • 6
    Electronic Resource
    Electronic Resource
    Variational energy band theory for polarons: Mapping polaron structure with the Merrifield method (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 5622-5630 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we revisit from a contemporary perspective a classic problem of polaron theory following the variational approach originally taken by Merrifield. Polaron structure is represented by a variational surface giving the optimal values of the complete set of phonon amplitudes for every value of the joint exciton–phonon crystal momentum κ. Quantities such as complete ground state energy bands (all κ) and effective masses (κ=0) are obtained. The parameter space of the problem is mapped, with careful attention given to the self-trapping transition. Through this examination of the complete parameter space at all κ, it is found that the common notion of a sharp self-trapping phenomenon associated with κ=0 is a limiting aspect of a more general finite-κ phenomenon. The idea of polaron Wannier states is addressed briefly, and the properties of such states tied to characteristics of the polaron energy band. The successes and failures of the Merrifield method are assessed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473598
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  • 7
    Electronic Resource
    Electronic Resource
    Expression of constitutive heat shock protein-70 in normal (non-stressed) rabbit urinary bladder tissue (1993)
    Springer
    Molecular and cellular biochemistry 121 (1993), S. 13-19 
    Details
    ISSN: 1573-4919
    Keywords: heat shock protein 70 (HSP-70) ; urinary bladder smooth muscle ; immunoblotting ; immunofluorescence ; laser densitometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of constitutive HSP-70 in the urinary bladder was determined by SDS-PAGE and western blotting using a mouse monoclonal antibody against HSP-70. The western blot analysis showed that the mouse anti-HSP-70 cross-reacted with a 70 kDa protein present in the extracts of the urinary bladder muscle and mucosa. Densitometric scanning of the western blots allowed us to specifically quantitate the relative amounts of the HSP-70. The quantitation of the HSP-70 by combining immunoblotting and densitometry using a laser scanner is reproducible and this technique requires only a small amount of tissue. The amounts of HSP-70 can be estimated from a standard curve of nanogram(ng) of HSP-70 vs absorption from the immunoblots. The amounts of HSP-70 in the muscular and mucosal layers in the body of the urinary bladder are more than those in the base of the bladder. The presence of HSP-70 in the muscle and mucosal epithelium of the bladder was demonstrated by immunohistochemical analysis of freshly removed tissue from the base and the body of bladder from normal animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00928695
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  • 8
    Electronic Resource
    Electronic Resource
    Partial outlet obstruction of the rabbit bladder results in changes in the mitochondrial genetic system (1994)
    Springer
    Molecular and cellular biochemistry 141 (1994), S. 47-55 
    Details
    ISSN: 1573-4919
    Keywords: bladder ; outlet obstruction ; mitochondria ; genetic function ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In the rabbit, partial outlet obstruction of the urinary bladder results in significant changes in the physiology, cellular structure, and cellular metabolism of that organ. One of the most striking changes observed is a 50% decrease in oxidative metabolism. Here we investigate whether the function of the mitochondrial (mt) genetic system is altered in rabbit bladder tissue following partial outlet obstruction. Southern analyses of total DNA prepared from bladder tissue excised as a function of time after initiation of partial outlet obstruction showed that the relative number of copies of the mt genome decreases as much as 10-fold during the first 7 d after obstruction, and that this attenuated mt genome copy number is maintained until at least 14 d post-obstruction. Northern analyses, in contrast, showed that mtCOII and cytochromeb transcript levels initially decrease but recover to control levels by about 5 d after obstruction; that level is maintained through 14 d post-obstruction. Enzymatic analysis of cytochrome oxidase and NADH cytochromec reductase activities in obstructed bladder tissue gave results which paralleled the pattern in the mt RNA analyses. Surprisingly, transcript levels for the mt-related nuclearCOIV gene rapidly decreased to about 50% of control levels following obstruction and remained there until 14 d post-obstruction. These results indicate that partial outlet obstruction of the rabbit bladder leads to significant changes in the status and expression of the mt genetic system in bladder tissue. The maintenance of mt transcription under such circumstances may be an attempt to keep mt protein products at control levels, and this transcriptional adjustment may be responsible in part for the observed maintenance of bladder function during the initial (compensated) period which follows partial outlet obstruction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00935590
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  • 9
    Electronic Resource
    Electronic Resource
    Expression of stress proteins (HSP-70 and HSP-90) in the rabbit urinary bladder subjected to partial outlet obstruction (1994)
    Springer
    Molecular and cellular biochemistry 130 (1994), S. 49-55 
    Details
    ISSN: 1573-4919
    Keywords: stress protein 70 and 90 (HSP-70 and-90) ; urinary bladder outlet obstruction ; Western blot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Partial obstruction of the rabbit bladder outlet induces a rapid hypertrophy characterized by increased bladder mass, increased smooth muscle content, and increased collagen deposition. In addition, partial outlet obstruction induces decreased contractile responses to both field stimulation and postsynaptic receptor stimulation. Although the morphological and contractile responses to partial outlet obstruction have been well characterized, there is little information on the cellular and molecular mechanisms of these changes. In a previous study, we demonstrated that one of the earliest genes to be expressed following partial outlet obstruction in rabbits was the gene expressing stress protein-70 (HSP-70). In order to further define the genetic and molecular basis of these responses, the expression of stress gene products HSP-70 and HSP-90 in rabbit urinary bladder subjected to partial outlet obstruction has been quantitatively evaluated by Western blot coupled with laser densitometry using anti-HSP-70 and-90 monoclonal antibodies. The data show that stress gene products HSP-70 and HSP-90 are constitutively expressed in control rabbit bladder tissue and transiently increased following partial outlet obstruction. Increased content of HSP-70 was detected at 6 hr after obstruction and reached a maximum (2.7-fold over the control level) at 24 hr. Increased HSP-90 was also detected at 6 hr but reached a maximum (4.5-fold over the control level) at 12 hr. By 7 day post-obstruction, the content of these two proteins returned to the control levels. This study suggests that alterations of stress gene expression resulting in increased HSP-70 and 90 may play an important role in the response of the bladder to partial outlet obstruction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01084267
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  • 10
    Electronic Resource
    Electronic Resource
    Assessment of stress gene mRNAs (HSP-27, 60 and 70) in obstructed rabbit urinary bladder using a semi-quantitative RT-PCR method (1995)
    Springer
    Molecular and cellular biochemistry 148 (1995), S. 1-7 
    Details
    ISSN: 1573-4919
    Keywords: bladder outlet obstructions ; stress proteins ; HSP-27,-60, and-70 ; reverse transcription reaction (RT) ; polymerase chain reaction (PCR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Stress proteins (HSPs) participate in the cellular response to various stresses including hyperthermia, hypoxia and injury. A previous work using northern blot analysis demonstrated increased expression of stress protein 70 (HSP-70) in rabbit bladder tissue subjected to partial outlet obstruction. In order to determine if the increased expression was specific for HSP-70 or, alternatively, indicated a generalized stress protein response, a modified quantitative RT-PCR technique was used to quantitate HSP mRNAs (HSP-27, 60, and 70) in normal and obstructed rabbit urinary bladder tissues. The results show the following: 1) The modified semi-quantitative RT-PCR is a sensitive and reproducible technique for detecting mRNA in bladder tissue. 2) Constitutive levels of HSP-27, HSP-60, and HSP-70 mRNAs were detected in control bladder tissues; the relative signal intensity was highest for HSP-70 and lowest for HSP-27.3) A transient increase in HSP mRNAs was observed after obstruction; the mRNAs of HSP-27, 60 and 70 increased 4.3-, 5.6-, and 2.4-fold, respectively, at 24 h following obstruction, then gradually returned to control levels by the end of one week post-obstruction and remained stable up to 14 days post-obstruction. These data indicate that the modified quantitative RT-PCR is a useful technique for detecting mRNA in bladder tissue; the stress response which occurs in rabbit urinary bladder tissue following partial outlet obstruction is a general phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00929496
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