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  • 1
    Electronic Resource
    Electronic Resource
    Numerical calculation of the height of velocity-matching step of flux-flow type Josephson oscillator (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4703-4709 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The height of the velocity-matching step (VM step) of a flux-flow type Josephson oscillator is studied systematically by numerical simulations. It is defined by the phase velocity of the propagating fluxons equaling that of the electromagnetic wave in the junction structure. The height of VM step (γm) is an important parameter for the practical application of such a device. The results presented on γm are important data in order to save computer time in the simulation of electromagnetic properties, such as the output voltage, at the velocity-matching condition. The detailed simulations were performed using the perturbed sine-Gordon equation (PSGE) with a uniformly distributed bias current γ. The PSGE was solved numerically by using an implicit finite-difference scheme. The distributions of electromagnetic fields in an overlap, long Josephson junction in the flux-flow state are mapped. The parameters influencing γm are discussed. We show that γm increases almost linearly with an external magnetic field βe or with the quasiparticle damping α, while it is less dependent on surface loss β. γm increases slowly with junction length above a minimum length, and it levels out at long lengths. We also present an approximate expression for γm which fits numerical results well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346150
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  • 2
    Electronic Resource
    Electronic Resource
    Theory of operation of high temperature Josephson fluxon-antifluxon transistor (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5483-5488 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We provide two qualitative models for the operation of Josephson fluxon–antifluxon transistor based on the pendulum model and image currents induced in the junction. This device, which is a variant of a Josephson vortex flow transistor, utilizes high temperature superconductor long Josephson junctions with a control line on top of the junction. Our models are consistent with the experimental observation that the coupling efficiency increases with this geometry. We also provide a quantitative model using numerical simulations to confirm the static and dynamic characteristics predicted by the intuitive models. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362738
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  • 3
    Electronic Resource
    Electronic Resource
    High-temperature superconducting Josephson fluxon–antifluxon transistors (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3257-3259 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have realized the Josephson fluxon–antifluxon transistor (JFAT) in high temperature superconductivity using an asymmetric control line on top of either bicrystal junctions or Co-doped YBa2Cu3Ox superconductor–normal–superconductor (SNS) junctions. We have measured current gains as high as 6 for 30 μm-wide bicrystal JFATs (30 K) and as high as 3 for Co-doped SNS JFATs (50 K). An improvement in gain over the Josephson vortex flow transistor, due to improved coupling efficiency, is demonstrated. There is also a reduction of control line inductance that should lead to an improvement in gate speed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118028
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  • 4
    Electronic Resource
    Electronic Resource
    Linewidth measurements of Josephson flux-flow oscillators in the band 280–330 GHz (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 3195-3197 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An integrated receiver consisting of two Josephson flux-flow oscillators and a superconductor-insulator-superconductor (SIS) mixer has been used to measure the linewidth of the oscillators. The oscillators are coupled to the SIS mixer using two centerfed interdigital capacitors, one of which with a fairly weak (−20 dB) coupling. By biasing the two oscillators (a few microvolt apart) on their velocity matching steps, the two resulting oscillations (280–330 GHz) were mixed in the SIS mixer. The difference frequency was amplified and detected on a spectrum analyzer. The combined linewidth of the two oscillators was 2.1 MHz throughout the band. The calculated available power incident on the SIS mixer was 430 nW at 320 GHz. The rf power from the oscillators, which could be tuned by changing the current bias, is high enough to pump the SIS mixer optimally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109127
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  • 5
    Electronic Resource
    Electronic Resource
    Improved step edges on LaAlO3 substrates by using amorphous carbon etch masks (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1177-1179 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a technique for the fabrication of sharp and straight step edges on LaAlO3 (LAO) substrates by ion milling. An electron beam lithography defined amorphous carbon film was used as an etch mask. It had very low ion milling rate and was easily prepared and removed. Atomic force microscopy was used to determine the step profile. YBa2Cu3O7 step edge junctions fabricated at the LAO steps show promising results. An IcRn product of 1 mV was obtained at 30 K. A Fraunhofer-like magnetic field dependence of Ic was obtained up to ±2 Φ0. One weak link or possibly identical weak links in series for these step edge junctions were observed from the current-voltage (I-V) curves as well as from the magnetic field dependence of the I-V curves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112138
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  • 6
    Electronic Resource
    Electronic Resource
    Flux-flow transistors based on long YBa2Cu3O7−δ bicrystal grain boundary junctions (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1153-1155 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Josephson flux-flow transistors were made from long YBa2Cu3O7−δ bicrystal grain boundary junctions. A normal metal loop, separated from the junction by an SiO layer, was used as the current control line. The line modulated the critical current, Ic , which for temperatures ≤60 K showed the typical dependence for a long junction, while at higher temperatures the regular small junction modulation was seen. Current gain larger than unity was obtained below 70 K. The current gain increased with the junction length, and varied roughly like (square root of)Ic when decreasing the temperature. A transresistance larger than 5 Ω was obtained at 15 K. Better performance is expected from junctions with higher current densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110836
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  • 7
    Electronic Resource
    Electronic Resource
    Underdamped long Josephson junction coupled to overdamped single-flux-quantum circuits (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1863-1865 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a circuit that integrates an underdamped long Josephson junction with overdamped single-flux-quantum (SFQ) circuits. We confirm that the resonant soliton modes in the long junction are not affected by SFQ cells coupled to the junction, and demonstrate that the radiation frequency and linewidth of the soliton resonances can be measured with SFQ T-flip-flops. Our experimental results also show that a 4π quantum mechanical phase leap at the end of the long junction, which is due to the reflection of a soliton, creates two single flux quanta propagating in the overdamped Josephson transmission line. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119423
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  • 8
    Electronic Resource
    Electronic Resource
    The DNA excision repair system of the highly radioresistant bacterium Deinococcus radiodurans is facilitated by the pentose phosphate pathway (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 48 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Deinococcus radiodurans is highly resistant to radiation and mutagenic chemicals. Mutants defective in the putative glucose-6-phosphate dehydrogenase gene (zwf–) and the aldolase gene (fda–) were generated by homologous recombination. These mutants were used to test the cells’ resistance to agents that cause dimer formation and DNA strand breaks. The zwf – mutants were more sensitive to agents that induce DNA excision repair, such as UV irradiation and H2O2, but were as resistant to DNA strand break-causing agents such as methylmethanesulphonic acid (MMS) and mitomycin C (MMC) as the wild-type cells. Analysis of the cytoplasmic fraction of zwf– cells showed that the concentrations of inosine monophosphate (IMP) and uridine monophosphate (UMP) were only 30% of those found in the wild-type cells. The fda– mutants were slightly more resistant to UV light and H2O2. Results suggested that the deinococcal pentose phosphate pathway augmented the DNA excision repair system by providing cells with adequate metabolites for the DNA mismatch repair.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03486.x
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  • 9
    Electronic Resource
    Electronic Resource
    Glycosylation using a one-electron-transfer, homogeneous reagent. Application to an efficient synthesis of the trimannosyl core of N-glycosylproteins
    Amsterdam : Elsevier
    Carbohydrate Research 236 (1992), S. 73-88 
    Details
    ISSN: 0008-6215
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0008-6215(92)85007-M
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  • 10
    Electronic Resource
    Electronic Resource
    Spiro[(2,3-époxycyclohexane)-1:4'-(2',3'-dihydro-8'-méthoxybenzo-4H-pyranne)] (1992)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 885-887 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270191011605
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