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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 121-123 (Mar. 2007), p. 1325-1328 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Nanocrystalline ZnO powders, whose crystalline sizes were 14.3, 21.2,24.1, and 35.3 nm, respectively, were prepared by homogeneous precipitation process.Nanocrystalline ZnO powders were characterized with powder X-ray diffractometer(XRD), transmission electron microscopy (TEM) and X ray photoelectronspectroscopy (XPS). The performance of desulfurization of H2S at room temperaturewas investigated. Results demonstrated that the smaller the size of nanocrystallineZnO, the darker the color of desulfurization products would be, which was moresimilar to the characteristics of multi-sulfide results, indicating that the mechanism ofdesulfurization of nanocrystalline ZnO was not the same as that of the analytical pureZnO. Nanocrystalline ZnO improved the performance of desulfurization of H2S atroom temperature, and the activity time of nanocrystalline ZnO (14.3 nm) for thedesulfurization was 34 times that of analytical pure ZnO at absence of oxygen. Whenthe oxygen was present in reaction, the accuracy of desulfurization was improved, inwhich H2S was prone to be oxidized into element S, and SO2 was not detected atoutlet of the reactor
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 44.50.+f ; 68.65.+g
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A complete theoretical treatment for the determination of thermal diffusivity of superlattices by the “mirage” technique has been performed. An effective “medium approximation” model of the thermal conductivity and thermal diffusivity of both sublayers is presented, which is different from the simple models with the thermal diffusivity or thermal conductivity in series or parallel. The numerical calculation of the transverse component of the probe beam deflection in the “mirage” effect shows that the results obtained from the complete thermal-wave theory and the “medium approximation” model, for the optically and thermally thick superlattices, are in good agreement with each other. However, the further study on the thermally thin superlattices shows that either the series or the parallel model of the thermal conductivity should be chosen according to whether the thermal impedance of the superlattice is larger or less than that of substrate, respectively.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1084
    Keywords: Key words: Lung neoplasms ; Thin-section CT ; Tumor growth ; Cancer screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to clarify the thin-section CT features of small peripheral carcinomas of the lung on the basis of pathologic findings of tumor growth patterns. Thin-section CT and pathologic correlation was evaluated in 19 patients with surgically verified small peripheral carcinomas of the lung ( 〈 20 mm in size) that had been detected in a screening trial for lung cancer using spiral CT. Four thin-section CT types of nodules were observed: (a) type L1 (4 of 19, 21 %), a fairly well-defined nodule with ground-glass attenuation, corresponding to tumor lepidic growth without alveolar collapse; (b) type L2 (4 of 19, 21 %), a partly lobulated nodule with a low but inhomogeneous attenuation, corresponding to tumor lepidic growth with scattered foci of alveolar collapse; (c) type L3 (4 of 19, 21 %), an ill-defined nodule with an irregularly shaped higher-density central zone in a ground-glass attenuation peripheral zone, accompanied by convergence of the bronchovascular structures from the surrounding lung parenchyma, which corresponded to desmoplastic response in the central zone and to tumor lepidic growth in the peripheral zone; and (d) type H (7 of 19, 37 %), a well-defined nodule with a solid homogeneous attenuation, corresponding to tumor hilic growth. Thin-section CT features of small peripheral carcinomas of the lung can be classified into four types, based on the density distribution of the tumor, which reflect the histologic findings.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1084
    Keywords: Digital radiography ; Image processing ; Subtraction ; Thorax ; Tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Digital tomosynthesis makes it possible to reconstruct multiple tomographs from digital data obtained during a single tomographic motion and permits digital processing, which adds a number of special advantages to the well-known advantages of conventional tomography. We performed digital tomosynthesis with a fluororadiographic TV unit with tomographic function which was capable of producing pulsed low-and high-energy X-rays alternately, and we studied digital image processing to improve the image clarity of the reconstructed tomographs. To identify the optimal parameters for processing image data by means of spatial frequency filtration we evaluated the spatial frequency distribution of image data in linear tomographs of the lung, and on the basis of the results of this study we developed several types of digital image processing to reduce tomographic blur and system noise, to improve visualisation of faint opacities, to reduce resistant tomographic blur as well as overall blur, and to generate low-noise bone images based on dual-energy subtraction tomosynthesis.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 128 (1999), S. 86-91 
    ISSN: 1432-1106
    Keywords: Key words Grip force ; Dynamics ; Collision ; Anticipation ; Forward models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This experiment investigated the prediction of load force (LF) in impulsive collisions inferred from anticipatory adjustments of grip force (GF) used to stabilise a hand-held object. Subjects used a precision grip to hold the object between thumb and index finger of their right hand and used the arm either: (1) to move the object to produce a collision by hitting the lower end of a pendulum, causing it to swing to one of three target angles, or (2) to hold the object still while receiving a collision produced by the experimenter releasing the pendulum from one of three angles. Visual feedback of the pendulum’s trajectory was available in the production task only. In all conditions, subjects increased GF in advance of the collision. In receiving the collision without advance information, subjects set GF levels to the mid-range of the experienced forces. When subjects possessed knowledge about the maximum angle of pendulum swing – either because they were going to produce it or because they were verbally informed – magnitude of the anticipatory-GF magnitude response was scaled to the predicted LF magnitude. Furthermore, GF was scaled to LF with a higher gain when producing compared to receiving the collision. This suggests that updating forward models through a semantic route is not as powerful as when the updating is achieved through the more direct route of dynamic exploration.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Journal of metastable and nanocrystalline materials Vol. 23 (Jan. 2005), p. 105-108 
    ISSN: 1422-6375
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: By means of solid-state reactions method, ZnSnO3 nanoparticles were prepared in the reactions of ZnCl2 and SnCl4·5H2O with KOH in the presence of added KCl crystal, and were assembled into 3-D aggregates with tetragonal-like shape in the size range of 20-200 nm. The products were characterized by powder X-ray diffraction (XRD), and the microstructures of the samples were investigated by transmission electron microscope (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscope (HRTEM) in detail. Probable mechanisms for the formation of such tetragonal-like shape of ZnSnO3 3-D aggregates are proposed
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Applied mechanics and materials Vol. 10-12 (Dec. 2007), p. 466-470 
    ISSN: 1662-7482
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Biped robot with heterogeneous legs (BRHL) is a new pattern humanoid robot. Thispaper first introduces the conception, research purpose and configuration of HRHL. Thencoordinated dynamics model and magneto-rheological (MR) damper model are given. In the end,this paper discusses the control model of BRHL and gives combined control simulation. The resultindicates that intelligent bionic leg controlled by MR damper can track artificial leg’s gait well
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 1178-1182 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Thirteen bound vibrational levels (v=0–12) and a portion of the continuum of the Na2 a 3Σ+u state have been observed in rotationally resolved fluorescence spectra from single rotation-vibration levels of two 3Πg states. These 3Πg states were populated by A 1Σ+u∼b 3Πu perturbation-facilitated optical–optical double resonance from the X 1Σ+g state. Analysis, using a LeRoy–Bernstein long-range expression for the energy levels, produced an RKR potential curve from which were derived, in combination with recent results obtained by Barrow et al. on the X 1Σ+g state, principal constants for the a 3Σ+u state of re=5.0911(30) A(ring), De=174.45(36) cm−1, ωe=24.47(21) cm−1, and Te=5848.21(35) cm−1. In addition, the exchange interaction between two ground state Na atoms was found from the difference between the X 1Σ+g and a 3Σ+u potential curves to be well represented by an exponential, A exp(-BR), A=9.44(71)×105 cm−1, B=1.448(14) A(ring)−1 for R(approximately-greater-than)5.0 A(ring).
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 142-149 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The advantages of the cut or section method in describing quasicrystal structures and phason defects are given. The real and reciprocal quasilattice formulation is derived straightforwardly. It is shown that the linear phason strain which leads to the quasilattice distortion is equivalent to a rotation of physical space relative to the high-dimensional space. A continuous rotation of the physical space will make the quasilattice deviate from its idealized form and turn gradually into a periodic lattice. The derivation of a geometrical relationship between the icosahedral quasilattice and the corresponding b.c.c. lattice becomes simple and clear. This will be beneficial to the construction of a quasicrystal structure model by reference to the corresponding b.c.c. crystal structure.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 473-478 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A possible approach to direct phasing of quasicrystal diffraction data is described. The data are first converted to a set of structure-factor amplitudes of a multidimensional crystal. The Patterson function of the quasicrystal is used to derive the converting factor. A direct method is then used to solve the phase problem in multi-dimensional space. The method has been tested with a hypothetical one-dimensional quasicrystal yielding a satisfactory result.
    Type of Medium: Electronic Resource
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