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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 29 (2000), S. 429-438 
    ISSN: 1432-1017
    Keywords: Key words Horseradish peroxidase ; Spectral hole burning ; Protein isothermal compressibility ; Stark effect ; Porphyrin Q-band splitting ; AbbreviationsHRPC isozyme C of horseradish peroxidase ; MP mesoporphyrin IX ; MP-HRP mesoporphyrin IX horseradish peroxidase C ; MgMP ; Mg(II)-mesoporphyrin IX ; MgMP-HRP Mg(II)-mesoporphyrin IX horseradish peroxidase C ; NHA 2-naphthohydroxamic acid ; SHB spectral hole burning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract To clarify the role of metal ion coordination in horseradish peroxidase C (HRPC), the effect of pressure and of an externally applied electric field on spectral holes was compared for both metal-free and Mg-mesoporphyrin-substituted horseradish peroxidase C (MP-HRP and MgMP-HRP), as affected by the binding of 2-naphthohydroxamic acid (NHA). The data are compared to earlier studies performed on the same derivatives. Results obtained for MP-HRP show the presence of a predominant MP tautomer, as well as that of another small population with different pocket field and isothermal compressibility (0.12 vs 0.24 GPa−1). Binding NHA induces the formation of two new almost equal populations of MP-HRP tautomer complexes and the protein compressibility in both forms is increased to 0.50 and 0.36 GPa−1. The protein structure becomes much softer than in the absence of NHA. Binding the same substrate to MgMP-HRP resulted in MgMP adopting a single conformation with no compressibility changes, while without NHA, two forms were possible. Stark effect results show charge rearrangement upon substrate binding in both cases. We propose that it is the presence of the metal that stabilizes the structure during the reorganization of the protein matrix induced by the substrate binding event. With the metal, only one conformation is adopted, without significant structural rearrangement but with charge redistribution. The dissociation constants determined for NHA binding to both derivatives and to native HRPC show that studies using mesoporphyrin and Mg-mesoporphyrin derivatives are relevant to investigating the specificity of the substrate-binding pocket in this enzyme.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 15 (1964), S. 43-49 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 5565-5570 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Site-selective excitation of Eu+3 β‘-alumina into the 5D0 level (568–579 nm) shows that the europium ion occupies at least two types of site distributions. The first distribution occurs at the higher energy of the tuning range and has site symmetry C3v or C3. It corresponds to the crystallographic Beevers–Ross position. The other site distribution is observed at lower energy and is associated with the mid-oxygen crystallographic position (site symmetry: C2h ). We also show that interpretation of the site-selective spectroscopy of Eu+3 β‘-alumina must take into account the occurrence of site-to-site energy transfer linked to vibronic coupling phenomena.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The beating between two colinear Nd-YLF and Nd-YAG lasers in a homogeneous plasma generates intense relativistic plasma waves associated with a high longitudinal electric field of the order of 1 GV/m. It is shown that these electron waves couple with ion waves in the regime of modulational instability. Electric field amplitude and saturation time obtained by Thomson scattering are in agreement with theoretical predictions taking this mechanism into account.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 1972-1978 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A plasma with a modulated density of ñ/n=8% was produced by illuminating a grating with a ruby laser at an intensity of 1010 W/cm2. A CO2 laser of intensity 3×1011 W/cm2 then irradiated this modulated plasma and generated plasma waves. The phase speeds of the waves are vph = ±ω0/kg, where kg is the wave number of the grating and ω0 is the frequency of the CO2 laser. Electrons were injected at an energy of 92 keV in one of the plasma waves. In order for the phase speed of the wave to synchronize with the accelerating electrons, a grating with constantly increasing line spacing (chirped) was used. Some electrons accelerated by 70 keV in 70 μm (gradient of 1 GeV/m) were detected, but the number of accelerated electrons was three orders of magnitude less than the expected value. This discrepency is the result of a large electric field perpendicular to the surface of the grating, which deflects the electrons onto the grating. This detrimental field is produced when fast electrons are emitted by the plasma, and leave it positively charged. Some techniques to remedy this difficulty are proposed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 2708-2714 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A 6 nsec 1010 W/cm2 ruby laser pulse irradiates a grating with spacing in the 6–35 μm range. The expansion of the plasma above the surface is observed using interferometry and shadowgraphy. The plasma is found to be modulated with ñ/n up to 8%. Such a plasma can be used to accelerate charged particles.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 839-853 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Pulsed transverse electric (TE) glow discharges used to produce population inversions in gas lasers at 1–20 atm require high-speed, high-voltage, high-current capacitor banks. In this article we first review and compare the circuits in common use to produce the required fast, self-sustained glow discharges in CO2, excimer, and N2 lasers. The parameters and circuit types given will be useful to future designers of pulsed gas lasers to design and to optimize any proposed circuit in order to yield any desired operating conditions and parameters. The n-stage circuit types presented are capacitor-transfer (C-C), L-C inversion, Marx bank, and fourfold L-C inversion, with their double-sided counterparts, and also their transmission-line counterparts, such as the Blumlein circuit. A one-parameter differential equation is developed which describes the general series C-L-R circuit. Electrical pulses measured on various lasers are compared with the differential equation solutions for various bank impedances and load resistances. We then present the design and measurements of a new automatically preionized, double-sided, L-C inversion circuit for an 800-mJ, TE CO2 laser, and compare it to previous systems. Methods to lengthen the discharge pulse, and some novel active mode locking techniques are discussed. We compare the L-C inversion circuit, the fourfold L-C inversion circuit, the conventional Marx bank, and the "double Marx bank'' for lasers and other applications, such as pulsed particle accelerators. Finally, we discuss capacitor bank interconnections, electro-optic probe systems, and various triggering methods.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Luminescence 55 (1993), S. 159-166 
    ISSN: 0022-2313
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Luminescence 59 (1994), S. 263-268 
    ISSN: 0022-2313
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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