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  • 1
    Electronic Resource
    Electronic Resource
    Improved coupling coefficient of laser radiation to aluminum by means of absorptive polymer coatings (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1829-1833 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The application of a polymer coating to aluminum is shown to provide a convenient energy-absorbing coating which increases the absorptance of the surface in a theoretically predictable way that is independent of the applied coating thickness. The dynamic absorptance of the coated surface for continuous-wave CO2 laser radiation was measured and found to agree with a theoretical model. Above temperatures of 400–500 °C, the polymer coating was completely removed, leaving a clean aluminum surface. It is shown that up to this temperature the absorptance of the surface was approximately 0.30 and also dependent on the incident laser intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336407
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  • 2
    Electronic Resource
    Electronic Resource
    Multichannel Fourier analysis of patterns in protein sequences (1993)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 3000-3006 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100114a028
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  • 3
    Electronic Resource
    Electronic Resource
    Protein Structure and Function (1972)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 23 (1972), S. 165-192 
    Details
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pc.23.100172.001121
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  • 4
    Electronic Resource
    Electronic Resource
    Structural Implications of the Myosin Amino Acid Sequence (1984)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 13 (1984), S. 167-189 
    Details
    ISSN: 0084-6589
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.bb.13.060184.001123
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  • 5
    Electronic Resource
    Electronic Resource
    Repeated folding pattern in copper–zinc superoxide dismutase (1980)
    [s.l.] : Nature Publishing Group
    Nature 285 (1980), S. 267-268 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The copper-zinc superoxide dismutase from bovine eryth-rocytes has a structural core of eight antiparallel -sheet strands which can be considered as either a flattened barrel24,25 or a two-layered sandwich with four strands on each face (see Fig. 1 A). The inter-strand connections are similar to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/285267a0
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  • 6
    Electronic Resource
    Electronic Resource
    Entropy phase dynamics (1993)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 49 (1993), S. 75-85 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The entropy-dynamics method seeks maxima for the entropy of the electron density for N atoms in a crystal cell, when the Fourier amplitudes are fixed, but their phases are unknown. By analogy with molecular dynamics, the effective potential energy is the negative entropy V = −NS. The kinetic energy is proportional to the squared velocities of the electron densities at grid points in the map. It reduces to a sum of Fourier-mode rotor energies. Each rotor angle experiences a couple equal to the phase gradient of S, and local dynamical equilibrium yields a Boltzmann distribution of S. Discrete phase angles (e.g. signs) are treated as quantized rotor modes. The distributions depend on a popularity function of the entropy histogram. Trial calculations have been made of phase averages and correlations in a centrosymmetric projection of the membrane protein bacteriorhodopsin. The maximum-entropy solution and the correct solution do not always coincide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444992008102
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  • 7
    Electronic Resource
    Electronic Resource
    The pair-functional method for direct solution of molecular structures. I. Statistical principles (2001)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 125-139 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The pair-functional principle shows how to construct a unique statistical ensemble of strongly interacting atoms that corresponds to any feasible measured set of X-ray intensities. The ensemble and all its distribution functions are strictly periodic in the crystal lattice, so that each unit cell has exactly the same arrangement of atoms at all times. The mean particle density in the cell is uniform because the ensemble has undefined phases and the origin is not fixed. The atoms in this maximum-entropy ensemble interact through pairwise additive periodic statistical forces within the unit cell. The ensemble average pair-correlation function is matched to the observed originless Patterson function of the crystal. The derived pairing force then becomes approximately proportional to the Ornstein–Zernicke direct correlation function of the ensemble. The atoms have a many-body Boltzmann distribution and the logarithm of the likelihood of any particular conformation is related to its total pairing potential. The pairing potential of a group of atoms acts like a local field in the cell. This property is used in the pair-functional method. Molecular structures can be solved by a direct search in real space for clusters of atoms with high pair potentials. During a successful search, the atoms move from their original random positions to form larger and larger clusters of correctly formed fragments. Finally, every atom belongs to a single cluster, which is the correct solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767300013696
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  • 8
    Electronic Resource
    Electronic Resource
    The pair-functional method. III. The pairing forces (2001)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 152-162 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The theory of the pair-functional ensemble is developed to provide estimates of the pairing forces from experimental X-ray intensities. The statistical mechanics of the grand ensemble leads to a diagram expansion for the forces, in terms of the direct correlation function of the fluid ensemble combined with a series of small higher-order corrections. A simpler treatment, based on a biased Gaussian probability distribution, gives approximate formulae, valid for reflections of any type in all space groups. The role of symmetry is analysed. The entropy of an asymmetrical ensemble can always be increased by averaging it over equivalent positions of the atoms in the true space group, with the result that the atoms naturally tend to adopt the highest symmetry compatible with the data. In a cell with different types of atom, the atoms experience a single force function but they interact with a strength proportional to the products of their scattering factors. Numerical estimates are given for typical cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767300013714
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  • 9
    Electronic Resource
    Electronic Resource
    The pair-functional method for direct solution of molecular structures. II. Small-molecule tests (2001)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 140-151 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The new pair-functional direct method has been implemented and tested. Like the Patterson function, the pairing force has valuable imaging properties at high resolution. Two simple iterative algorithms were designed to refine on the total pair potential and the normalized intensity correlation coefficient of an atomic model. The first algorithm is a peak-picking method which selects the best-paired high peaks from a density map and then uses the strong reflections to generate a new Fourier filtered map. The second algorithm, the pair-and-square method, uses a tangent formula step instead of the Fourier and is a little more efficient. Computational experiments on a point-atom grid model, with perfect data, reached exact ab initio solutions for up to 600 atoms. Point-atom models were also solved by searching for reduced structures that contained as few as one quarter of the atoms. Seeded searches, guided by a small known fragment, solved up to 30000 atoms on the grid. Realistic tests on actual molecules showed that Sheldrick's [Acta Cryst. (1990), A46, 467–473] test structures of 50–200 atoms can be solved under a variety of conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767300013702
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  • 10
    Electronic Resource
    Electronic Resource
    A mathematical procedure for superimposing atomic coordinates of proteins (1972)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 28 (1972), S. 656-657 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A procedure is given which determines the best rigid-body rotation and translation that matches a given set of measured atomic coordinates to a fixed set of guide coordinates and minimizes the weighted sum of squared deviations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739472001627
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