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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric single cell spectra in snow algae (1998)
    Springer
    Polar biology 20 (1998), S. 303-310 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Single cell dielectric spectroscopy is introduced to investigate the passive electric properties of individual snow algal cells at different developmental stages. This non-destructive technique characterises the conductivities and permittivities of cell compartments, such as the cell wall, cytoplasm and membrane. To calculate the conductivities and permittivities in a quantitative manner, multi-shelled models are introduced. Dielectric spectra of snow algae are determined by the cell wall which has been found to have an extremely low permittivity of 3–5. Very likely this is a consequence of the high content of Al-Fe silicates and a low water content. Compared with cells and protoplasts of higher plants, the cell interior has a lower internal conductivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050307
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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Polyvinylidene fluoride film sensors for measurement of unsteady pressures on aerodynamic surfaces Part II: Application to a small-scale marine propeller in spatially distorted mean flow (1999)
    Springer
    Experiments in fluids 27 (1999), S. 85-91 
    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  Specially-developed Polyvinylidene Fluoride film sensors were used to measure the unsteady surface pressure on a small-scale marine propeller. Pressure response of the propeller blades to a spatially-varying-mean axial velocity flowfield was measured. Raw data were corrected for the thermally-induced sensor output in the nominally stratified flow with the aid of a blade-mounted constant-current anemometer. Corrected pressure measurements showed a phase lag in the blade pressure response relative to the mean velocity cycle. The necessity to consider thermally-induced sensor response was demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050332
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Polyvinylidene fluoride film sensors for measurement of unsteady pressures on aerodynamic surfaces Part I: Design, fabrication, calibration and demonstration (1999)
    Springer
    Experiments in fluids 27 (1999), S. 79-84 
    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  The design and calibration of a unique thin unsteady pressure sensor for use on small-scale marine propellers is presented. The Polyvinylidene Fluoride film-based sensor incorporates a miniature interface circuit suitable for use where space is a premium. Sensitivity of the sensor is comparable to high-quality microphones. Calibration is performed using an acoustic source and an industry-standard microphone. Evaluation of the sensor’s performance is presented for white noise unsteady pressure input. Results show excellent agreement between sensor-measured pressures and standard microphone-measured pressures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050331
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