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  • 1
    Electronic Resource
    Electronic Resource
    A resonant, dielectric micro-motor driven by low ac-voltages (〈6V) (1997)
    Springer
    Microsystem technologies 3 (1997), S. 168-170 
    Details
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract  An asynchronous, dielectric micro-motor consisting of an Al-SiO2 rotor of 50 to 200 μm diameter was driven with 4 or 8 circularly arranged electrodes in water. The motor elements were fabricated by micromachining. Each electrode was designed to be an oscillatory circuit with a sharp resonance frequency in the upper kHz-range. The resonances at all electrode tips increase the voltage in the stator-rotor gap by a factor of up to 15. As a result, the dielectric rotor operates in a sharp frequency window at 5 Vpp excitation as if driven with more than 75 Vpp. With square wave pulses, the higher order Fourier-components induce several changes in rotor spin direction within two frequency decades. The micro-motor has been driven for hours without noticeable wear. It developed high starting torques and was useful for circular water pumping. The system has the advantage of very sensitive frequency dependence and the low drive voltages (below 10 V) can be produced by most electronic circuits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005420050075
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  • 2
    Electronic Resource
    Electronic Resource
    The problem of pretreatment and unintentional variations in the fumigation-extraction method for time-course measurements in the field (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 167-170 
    Details
    ISSN: 1432-0789
    Keywords: Key words Analytical variations ; Root interference ; Root pre-extraction ; Fumigation-extraction ; Microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A control soil stored at 4°C was analyzed 38 times by fumigation-extraction during a period of 11 months to correct for variations caused by the analytical procedure. The difference in extractable C between fumigated and unfumigated samples oscillated around the average without a positive or negative trend. When data from contemporaneously extracted field samples were corrected with control soil data the variations were lowered. The deviations between corrected and uncorrected biomass C values had maxima of ±12%. Data obtained for seven dates using pre-extraction, wet-sieving, and centrifuging were compared with data obtained by the conventional procedure without any pretreatment. A negative difference from data obtained without pretreatment was found when the soil water content was decreased to 6%. The largest positive difference (+38%) was found in May during the period of highest root growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384450
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  • 3
    Electronic Resource
    Electronic Resource
    High-frequency electric-field trap for micron and submicron particles (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 425-432 
    Details
    ISSN: 0392-6737
    Keywords: Biophysical instrumentation and techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Four e-beam-processed, planar electrodes with gaps between 0.5 and 4 μm were used to create quadrupole electric-field trap. The electrodes were immersed in an aqueous particle suspension and driven by kHz to MHz signals of several volts amplitude. Micron and submicron particles could be stably trapped by negative dielectrophoresis. Latex beads of 1000, 600, 100 and 14 nm diameter could be concentrated between the electrodes (positive dielectrophoresis) or levitated as condensed cloud (negative dielectrophoresis). The results are surprising since polarisation forces depend on the volume of the particle and, up to now, it was expected that thermal forces would dominate the behaviour of particles with diameters 〈100 nm. However, micron-scaled electrode configurations allow the application of extremely strong fields (up to 20 MV/m) and open up new perspectives for microparticle handling and macromolecule trapping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457344
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  • 4
    Electronic Resource
    Electronic Resource
    The vibronically-resolved emission spectrum of disulfur monoxide (S2O): An algebraic calculation and quantitative interpretation of Franck–Condon transition intensities (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 5038-5055 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Emission spectra obtained from jet-cooled disulfur monoxide (S2O) molecules have been interpreted by means of a novel Lie algebraic formalism that makes possible the facile evaluation of multidimensional Franck–Condon factors. Fluorescence accompanying selective excitation of isolated vibronic bands in the S2O C˜ 1A′←X˜ 1A′(π*←π) absorption system has been dispersed under moderate spectral resolution, allowing assignment of ground state levels possessing up to 20 quanta of vibration in the ν2 S–S stretching mode [Evib(X˜)≤13 900 cm−1]. Aside from providing a rigorous and economical description for the inherently anharmonic nature of highly-excited polyatomic species, our algebraic approach enables quantitative information on molecular wavefunctions to be extracted directly from spectroscopic data. The emerging picture of S2O vibrational dynamics suggests that the X˜ 1A′ potential surface is substantially more "local" in character than the C˜ 1A′ manifold. While the observed pattern of X˜ 1A′ vibrational energies could be reproduced well through use of model Hamiltonians that include only diagonal anharmonicities in the local algebraic basis, successful treatment of the C˜ 1A′ state necessitated explicit incorporation of off-diagonal anharmonicities that lead to pervasive mixing of local vibrational character. This disparate behavior is manifest strongly in measured C˜–X˜ transition strengths, thereby allowing detailed investigations of Franck–Condon intensities to discern the underlying dynamics. Structural parameters deduced from algebraic analyses are in good accord with previous predictions of the change in S2O geometry accompanying π*←π excitation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479786
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  • 5
    Electronic Resource
    Electronic Resource
    Growth of anchorage-dependent mammalian cells on microstructures and microperforated silicon membranes (1996)
    Springer
    Journal of materials science 7 (1996), S. 85-97 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Anchorage-dependent cells (mouse fibroblasts L929 and 3T3) were cultivated on microstructures made by semiconductor technology. Both cell lines showed normal growth on silicon surfaces covered with microelectrode arrays as well as on microperforated silicon membranes with square pores made by anisotropic etching (5, 10 or 20 μm edge length at the top and 1.2, 6.2 or 16.2 μm at the bottom). The cells spread over the 5 and 10 μm pores, but mostly failed to cover the 20 μm ones. They were able to cross the silicon membrane through the pores and to grow and spread on the under side of the membrane. Small pores (about 1 μm2) impeded but did not prevent cells crossing the membrane. Medium and large pores were freely crossed. Negative dielectrophoresis was used to achieve accurate positioning of cells above pores or to repel them from the chip surface (a.c., square wave, 2.5 V peak-to-peak, 5 MHz). The results are discussed with respect to their microtool applications for single-cell technologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058719
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  • 6
    Electronic Resource
    Electronic Resource
    cis-Dipyridine Complex of Bis(ω-nitroacetophenonato)zinc(II) (1995)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 859-861 
    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/S010827019401293X
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  • 7
    Electronic Resource
    Electronic Resource
    cis-Dipyridine Complex of Bis(ω-nitroacetophenonato)manganese(II) (1996)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 307-309 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In the title compound, bis(ω-nitroacetophenonato-O,O')bis(pyridine)manganese(II), [Mn(C8H6NO3)2(C5H5N)2], the ω-nitroacetophenone (ω-nap) ligands chelate the manganese center, forming a six-membered ring with a bite angle of 80.13 (11)°. The distance from the metal to the nitro-O atom is longer than that from the metal to the carbonyl O atom, indicating that the latter is more strongly bound and suggesting a keto-to-enol mechanism preceding the binding of ω-nap to the metal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270195008304
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  • 8
    Electronic Resource
    Electronic Resource
    Accurate elastic scattering factors for lithium to argon based on correlated wavefunctions (1995)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 171-177 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Elastic scattering factors (or atomic form factors) f (s) for Li to Ar have been derived in the first Born approximation from ab initio MR-SDCI (multireference singly and doubly excited configuration interaction) calculations which recover between 90 and 99% of the estimated total correlation energy. The correlation effects on f (s) are contrasted with the relativistic effects known from the literature. Atomic form factors are presented that take into account correlation and relativistic contributions in an additive manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767394009748
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  • 9
    Electronic Resource
    Electronic Resource
    The Flame of Common Salt (1876)
    [s.l.] : Nature Publishing Group
    Nature 13 (1876), S. 448-449 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] HAVING been much interested in the progress of the investigations concerning the blue flame of common salt when thrown into a coal fire, I made the following experiments, by which I came to the conclusion that the origin of the blue flame is due to the presence of copper, which occurs in nearly ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/013448d0
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  • 10
    Electronic Resource
    Electronic Resource
    An experimental investigation of the sources of propeller noise due to the ingestion of turbulence at low speeds (1995)
    Springer
    Experiments in fluids 18 (1995), S. 277-287 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Noise radiation from a four bladed, 10 in. diameter propeller operating in air at a rotational speed of 3000 RPM and a freestream velocity of 33 ft/s was experimentally analyzed using hot-wire and microphone measurements in an anechoic wind tunnel. Turbulence levels from 0.2 to 5.5% at the propeller location were generated by square-mesh grids upstream of the propeller. Autobicoherence measurements behind the blade trailing edges near the hub and tip showed regions of high phase-coherence between the blade-passage harmonics and the broadband frequencies. Inflow turbulence reduced this coherence. By relating the fluctuation velocities in the propeller wake to the unsteady blade forces, the primary regions of tonal noise generation have been identified as the hub and tip regions, while the midspan has been identified as a region responsible for broadband noise generation. These measurements were complimented by cross-spectra between the propeller wake-flow and the measured sound. The effect of turbulence on the radiated noise level showed an overall increase of 2 dB in the broadband levels for every 1% increase in turbulence. This effect varied for different frequency bands in the acoustic spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195098
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