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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 7144-7154 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Tracer diffusion on a surface is studied by performing Monte Carlo simulations in a two-dimensional noninteracting lattice gas with an emphasis on high coverages. Three different models were investigated: (1) The canonical model (CM), where the background particles on the surface can only diffuse in the parallel direction to the surface. (2) The grand canonical model (GM), where background particles are only allowed to desorb from or adsorb onto the surface (which means that the total number of particles on the surface fluctuates). (3) The combined grand canonic model (CGM), where background particles may both move in parallel (diffusion) or perpendicular (adsorption–desorption) to the surface. In all of these models the tracer is allowed to move only parallel to the surface. The results of the simulations were cast in the form of a correlation factor (the ratio between the calculated diffusion coefficient and the diffusion coefficient of a mean-field approximation). Correlation factors of the tracer were calculated for different surface coverages, and for different ratios between the jump rate of the tracer and the adsorption–desorption rate or/and jump rate of the background particles. In all of the cases, correlation factors showed an identical qualitative behavior: they decreased as surface coverage increases and as background particles became slower. This dependence of the correlation factors on surface coverage and on background particles rate becomes stronger for high surface coverage (above 70%), and for very slow background particles. Comparison to the theory of Harrison and Zwanzig (HZ) shows that it predicts reasonably well the general tendency of the correlation factors in different conditions and even agrees very well with the combined grand canonical simulations (Model 3) when the rates of adsorption–desorption and diffusion of background particles are of the same order.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1728-1730 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a new source of femtosecond light pulses which is broadly tunable in the infrared. A singly resonant optical parametric oscillator based on a thin crystal of KTiOPO4 is pumped by intracavity femtosecond pulses at 620 nm from a standard colliding-pulse passively mode-locked dye laser. Oscillation results in stable, continuous outputs of femtosecond pulses at 108 Hz repetition rate and milliwatt average power levels in both signal and idler beams. Here we demonstrate tuning from 820 to 920 nm and 1.90 to 2.54 μm with a single set of mirrors. With multiple sets of mirrors, continuously tunable outputs from ∼0.72 to ∼4.5 μm should be possible, making this a uniquely versatile femtosecond laser source.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 2211-2213 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intracavity doubling in β-BaB2 O4 (BBO) of femtosecond pulses into the ultraviolet with high efficiency is reported. Pulse widths down to 43 fs at a 108 Hz repetition rate and outputs as high as 20 mW per arm of the femtosecond laser on a continuous-wave basis can be achieved. The ultraviolet pulse widths were determined through detailed cross-correlation measurements based on sum-frequency mixing to 210 nm in ultrathin BBO crystals.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 579-583 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A device is presented that sweeps out programmable optical delays of 300 ps (or less) at 30 Hz, with shorter-delay scans possible at much higher rates. It is compact, vibration-free, linear to within 0.02%, and has a position repeatability of 1 part in 105. With this scanner and a PC-based signal-averaging data acquisition system, ultrafast autocorrelation measurements with very high signal/noise are demonstrated in both the fs and ps domains.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 30 (2000), S. 229-262 
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The increasingly rapid transition of the electronics industry to high-density, high-performance multifunctional microprocessor Si technology has precipitated migration to new materials alternatives that can satisfy stringent requirements. One of the recent innovations has been the substitution of copper for the standard aluminum-copper metal wiring in order to decrease resistance and tailor RC delay losses in the various hierarchies of the wiring network. This has been accomplished and the product shipped only since the fall of 1998, after more than a decade of intensive development. Critical fabrication innovations include the development of an electroplating process for the copper network, dual-damascence chem-mech polishing (CMP), and effective liner material for copper diffusion barrier and adhesion promotion. The present copper technology provides improved current-carrying capability by higher resistance to electromigration, no device contamination by copper migration, and the performance enhancement analytically predicted. This success of the shift to copper will accelerate the industry movement to finer features and more complex interconnect structures with sufficient device density and connectivity to integrate full systems on chips. The next innovation will be the introduction of low-dielectric constant material that, in combination with copper, will create added excitement as the industry learns how to utilize this new capability.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 173 (1990), S. 932-939 
    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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  • 7
    ISSN: 0005-2795
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Experimental Gerontology 6 (1971), S. 25-28+IN1-IN2+29-36 
    ISSN: 0531-5565
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 173 (1990), S. 932-939 
    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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  • 10
    ISSN: 1432-0428
    Keywords: Diabetic retinopathy ; rat model ; hypertension ; SHR ; aminoguanidine ; glycation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Arterial hypertension has been identified as a major secondary risk factor for diabetic retinopathy. However, the mechanisms by which hypertension worsens retinopathy are unknown. Inhibition of advanced glycation product formation prevents the development of experimental diabetic retinopathy in normotensive diabetic rats. In this study the effect of hypertension on the rate of diabetic retinopathy development and the formation of arteriolar thrombosis was evaluated. We also evaluated the effect of aminoguanidine, an inhibitor of advanced glycation end product formation on retinal pathology of diabetic hypertensive rats. After 26 weeks of diabetes, hypertension accelerated the development of retinopathy despite a lower mean blood glucose level than in the non-hypertensive group (diabetic spontaneous hypertensive rats (SHR) 16.00±6.83 mmol/l; diabetic normotensive Wistar Kyoto rats (WKY) 34.9±3.64 mmol/l; p〈0.0001). Diabetic SHR had nearly twice as many acellular capillaries as diabetic WKY (SHR diabetic: 91.9±7.5 acellular capillaries per mm2 of retinal area vs WKY diabetic: 53.7±8.5 acellular capillaries per mm2 of retinal area), and a 3.8-fold increase in the number of arteriolar microthromboses (SHR diabetic 23504±5523 μm2 vs SHR non-diabetic 6228±2707 μm2). Aminoguanidine treatment of SHR diabetic rats reduced the number of acellular capillaries by 50%, and completely prevented both arteriolar deposition of PAS-positive material and abnormal microthrombus formation. These data suggest that hypertension-induced deposition of glycated proteins in the retinal vasculature plays a central role in the acceleration of diabetic retinopathy by hypertension.
    Type of Medium: Electronic Resource
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