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  • 1
    Publication Date: 2014-10-14
    Description: Time-resolved soft X-ray photoelectron spectroscopy (PES) experiments were performed with time scales from picoseconds to nanoseconds to trace relaxation of surface photovoltage on the ZnO(0001) single crystal surface in real time . The band diagram of the surface has been obtained numerically using PES data, showing a depletion layer which extends to 1  μ m. Temporal evolution of the photovoltage effect is well explained by a recombination process of a thermionic model, giving the photoexcited carrier lifetime of about 1 ps at the surface under the flat band condition. This lifetime agrees with a temporal range reported by the previous time-resolved optical experiments.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 2
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1741-0444
    Keywords: Computer simulation ; Intravenous injection ; Radioactive tracer ; Transfer function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A method for solving the convolution-type integral equation $$y(t) = \int\limits_0^t x (t - t'){\mathbf{ }}h{\mathbf{ }}(t'){\mathbf{ }}dt'$$ is introduced from the analogy of the synthetic kernel approximation used in the analytical approach of the neutron slowing down problem. The method is chosen to find h(t), the transfer function, in the case where the values of the given data x(t) for the input of the system remain large during the sampling range and decrease almost monoexponentially at a sufficiently large t (time), which is usually the case with the intravenous injection of radioactive tracers. The accuracy of the method is examined using computer simulations. In these simulations, any smoothing technique is applied except for the determination of the analytical representation for the dominant part of x(t), which is called ‘the trend’ in this paper. It was found out that there was a possibility of obtaining transfer functions with accurate mean time value even when the given data x(t) and y(t) have large statistical fluctuations.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1741-0444
    Keywords: Mass spectrometer ; Response time ; Transcutaneous pCO2 ; Transcutaneous pO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The paper describes steady-state and transient responses of transcutaneous pO2 and pCO2 by mass spectrometry. The effects of factors affecting the responses were estimated from a mathematical model comprising the skin, a membrane of a sampler and a tube connected to a mass spectrometer. The effect of heading temperature, membrane thickness, gas permeabilities of the membrane and the dimensions of the connecting tube were verified experimentally. Transcutaneous tension (tcp) in O2 in a steady state was much more dependent on temperature and membrane thickness than in CO2. The transient response of the tcp was found to be improved, without decreasing the magnitude of the steady-state tcp, by a thinner membrane with a lower permeability and by a shorter connecting tube of a larger inner diameter. The method of calibration was also examined because the magnitude of tcp by mass spectrometry was influenced in particular by water vapour.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper deals with a three-dimensional deformation analysis of workpieces mounted in fixtures, where the workpieces are finite solid cylinders. The analysis is carried out using a three-dimensional theory of elasticity, where clamping forces caused by chucks are regarded as an axi-asymmetrical load. In numerical calculations, the effects of a number of chuck jaws, the diameter of workpieces and the grasping area on the roundness of the workpieces are shown. For verification, a three-dimensional photoelastic experiment is performed. In addition, the deformation of workpieces is measured by an electric comparator and by holography. The analytical results are satisfactorily consistent with the experimental results.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Key words: Cerebral ganglion ; Dorsal strand ; Granulated cells ; Immunoelectron microscopy ; Neural complex ; Pituitary gland ; Prolactin ; Halocynthia roretzi (Tunicata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Electron-microscopic studies of the neural complex (neural gland, dorsal strand, and cerebral ganglion) of an ascidian, Halocynthia roretzi, were performed, paying particular attention to the secretory systems. We found that cells scattered along the dorsal strand and neural cells in the cerebral ganglion contained electron-dense secretory granules of variable size. Immunoelectron-microscopic studies with an antiserum to bullfrog prolactin revealed that the secretory granules (100–250 nm in diameter) of some granulated cells contained a prolactin-like substance. Cells belonging to the neural gland and dorsal strand neither contained electron-dense granules nor showed immunoreactivity. The possibility that cells in the cerebral ganglion and those along the dorsal strand are phylogenetic progenitors of vertebrate adenohypophyseal cells is discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1617-4623
    Keywords: Key wordsEscherichia coli ; Deletion mutant ; Illegitimate recombination ; Repeated sequence ; Asymmetric crossover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosomal tonB gene of Escherichia coli was used as a target for the detection of spontaneous deletion mutations. The deletions were isolated in both recA + and recA − cells, and mutants carrying large deletions were identified because they also lacked part or all of the trp operon. The frequencies of tonB-trp deletion were 1.79 × 10−9 and 1.09 × 10−9 for recA + and recA − cells, respectively. We analyzed 12 deletions from recA + and 10 from recA − cells by cloning and direct sequencing. The deletions ranged in size from 5612 bp to 15142 bp for recA + and from 5428 bp to 13289 for recA − cells. Three deletions from recA + cells and five deletions from recA − cells were found to have occurred between short sequence repeats at the termini of the deletion, leaving one copy of the repeat in the mutant sequence. Seven deletions from recA + cells and three deletions from recA − cells did not have repeats at their termini; in these cases, the DNA sequences that are adjacent to the deletion termini in the wild-type are characterized by short (2–4 bp) repeats. From these results, a model is presented for the generation of deletion mutations which involves formation of an asymmetric crossover mediated by repeated sequences of 2- to 4-bp.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 57 (Sept. 2008), p. 73-79 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: This paper presents on a new damping element called the colloidal damper which is used aprinciple of surface extension force in nano pore. The direction acting of the surface extension forceof water in hydrophobic nano pore is different in pressurization and decompressurization processes[1,2]. This principle is applied to a damping element. The nano pore is constructed by silica gel. Asilica gel ball of 100-200 micrometer dia. has many nano pores of 5-20 nanometer dia. in it [3,4].The coated spherical silica gel and water are inserted in a piston - cylinder unit in order to work as adamper. If compression and decompression forces are added to the piston - cylinder unit (damper),water flows into and moves out the nano pore under balance of pressure. A contact angle ofcompression formed by the hydrophobic nano pore and water is larger than that of decompression.This difference of the contact angle produces a damping energy.In this paper, behavior of water in the pore of silica gel is investigated using the moleculardynamics. Dissipation energy of the colloidal damper is concerned with the contact angles of waterin the pore. So the contact angles are calculated for changing parameters, i.e. size of the pore, lengthof the hydrophobic material, velocity (pressure) of water flows into the pore. Then these results arecompared with the experimental ones
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 31 (1996), S. 3299-3308 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A lattice model has been developed to explore impact damage patterns in brittle materials. The damage evolution was modelled as a process involving the change of strain-energy distribution by cracking. Using a cubic lattice system, a large strain energy was supplied to the system surface. Crack growth initiated by this local energy supply was followed by means of computer simulations. The damage patterns were compared for systems which have different distributions of strain energy stored prior to the local energy supply. The simulations reveal a characteristic difference in the damage pattern. Impact damage for a system with a spatially fluctuating distribution of strain energy is limited around an impact point. Impact damage for a systen with a relatively uniform distribution of strain energy penetrates deeply. The results of the simulations are discussed in connection with the material evaluation and the material resistance.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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