Showing papers by "University of Science and Technology of China published in 1996"
TL;DR: A thermal reaction of Li3N and GaCl3 in which benzene was used as the solvent under pressure has been carried out for the preparation of 30-nanometer particles of gallium nitride (GaN) at 280°C, and the yield of GaN reached 80%.
Abstract: A thermal reaction of Li3N and GaCl3 in which benzene was used as the solvent under pressure has been carried out for the preparation of 30-nanometer particles of gallium nitride (GaN) at 280°C. This temperature is much lower than that of traditional methods, and the yield of GaN reached 80%. The x-ray powder diffraction pattern indicated that sample was mainly hexagonal-phase GaN with a small fraction of rocksalt-phase GaN, which has a lattice constant a = 4.100 angstroms. This rocksalt structure, which had been observed previously only under high pressure (at least 37 gigapascals) was observed directly with high-resolution electron microscopy.
398 citations
TL;DR: The celestial objects were observed for 1.5 h as they passed through the meridian and the shape of the reflecting Schmidt plate has to be changed with each different declination δ and in the tracking process.
Abstract: A special reflecting Schmidt telescope is used to observe celestial objects The telescope has an aperture of 4m, f ratio of 5, and a 5° field of view Its optical axis is fixed and tilted 25° to the horizontal that runs from south to north The celestial objects were observed for 15 h as they passed through the meridian The shape of the reflecting Schmidt plate has to be changed with each different declination δ and in the tracking process This is achieved with active optics The sky area to be observed is -10° ≤ δ ≤ +90° There are plans to place ~4000 optical fibers on the telescope focal surface that will lead to a dozen spectrographs
269 citations
241 citations
TL;DR: In this article, the authors constructed digital (t, s)-sequences in a prime-power base, where the quality parameter was defined as the least possible order of magnitude, using algebraic function fields over the finite field of order, which contained many places of degree 1 relative to the genus.
190 citations
TL;DR: In this paper, a linear theory underlying dynamic response of multilayered anisotropic plates with nonuniformly weakened bonding is presented from Hamilton's principle, and conditions of imposing traction continuity and displacement jump across each interface are used in modeling interphase properties.
Abstract: Rigorous kinematical analysis offers a general representation of displacement variation through thickness of multilayered plates, which allows discontinuous distribution of displacements across each interface of adjacent layers so as to provide the possibility of incorporating effects of interfacial imperfection. A spring-layer model, which has recently been used efficiently in the field of micromechanics of composites, is introduced to model imperfectly bonded interfaces of multilayered plates. A linear theory underlying dynamic response of multilayered anisotropic plates with nonuniformly weakened bonding is presented from Hamilton’s principle. This theory has the same advantages as conventional higher-order theories over classical and first-order theories. Moreover, the conditions of imposing traction continuity and displacement jump across each interface are used in modeling interphase properties. In the special case of vanishing interface parameters, this theory reduces to the recently well-developed zigzag theory. As an example, a closed-form solution is presented and some numerical results are plotted to illustrate effects of the interfacial weakness.
175 citations
TL;DR: The trace elements characteristics with flat REE pattern of these tholeiites are similar to those of MORB and their trace elements and Nd isotope compositions suggest an oceanic basin developed from a rift on the continental margin of the Yangtze Block during the late Paleozoic and closed in the Triassic.
Abstract: The metavolcanic rocks of greenschist fades developed at Heigouxia Valley in the Mian-Lue tectonic zone, South Qinling orogenic belt is a bimodal volcanic series. It is composed of K-poor, Na-rich tholeiite and dacite-rhyolite. The trace elements characteristics with flat REE pattern of these tholeiites are similar to those of MORB. The Sm-Nd whole rock isochron age of(242±21) Ma and Rb-Sr whole rock isochron age of (221±13) Ma of this metavolcanic series consistently indicate their rnetamorphic time. Their relatively high initial eNd value of +6.1 at the rnetamorphic age (242 Ma) suggest that the volcanic rocks were derived from a depleted MORB type mantle source. Their trace elements and Nd isotope compositions suggest an oceanic basin developed from a rift on the continental margin of the Yangtze Block during the late Paleozoic and closed in the Triassic, This is the first case clearly showing the existence of relict of late Paleozoic oceanic crust in Fast Qinling belt, which provides important evidence for the Mian-Lue tectonic zone as a structure zone.
165 citations
TL;DR: In this paper, a class of multivariate distributions that are mixtures of the positive powers of a max-infinitely divisible distribution is studied, where all weighted minima or maxima belong to a given location or scale family.
143 citations
TL;DR: In this article, the lightest oxygen isotope compositions so far reported for metarnorphic rocks in the world were found in mineral separates from an ec10gite pod (containing quartz-schist bands) in the Su-Lu terrane, East China.
Abstract: The unusually low Ö180 values of -10.3 to -6.8%0 are found in mineral separates from an ec10gite pod (containing quartz-schist bands) in the Su-Lu terrane, East China. These are the lightest oxygen isotope compositions so far reported for metarnorphic rocks in the world. Oxygen isotope equilibrium has been approached among the minerals within both ec10gite and quartz-schist. This not only yields the concordant isotope temperatures of 655 to 765°C, but also indicates that the rocks have exchanged oxygen isotopes with a very 180-depleted fluid. A plausible interpretation for the anomalously low Ö180 values of the ec10gite pod is that it equilibrated isotopically with ancient meteoric water prior to ec1ogite-facies metamorphism and thus preserved the premetamorphic isotopic signature. The hydrothermally altered basaltic rocks kept this isotopic signature through all stages of progressive UHP metamorphism as weIl as subsequent exhumation and cooling. This provides insight into limited crust-mantle interactions under ultrahigh pressure metamorphic conditions in the suture zone of a continent-continent collision. Key-words: oxygen isotopes, water-rock interaction, isotope geothermometry, ec1ogite, UHP metamorphism, continental collision, Dabie Mountains.
128 citations
TL;DR: In this article, the surface adsorptive and lattice oxygen govern the sensing properties of LaFeO3 and CaxLa1−x FeO3 ceramics, and partial substitution of La3+ with Ca2+ can enhance the sensitivity of the materials to reducing gases.
Abstract: LaFEO3 and CaxLa1−xFeO3 ceramic powders have been prepared by the coprecipitation method from La(NO3)3, Fe(NO3)3 and Ca(NO3)2 aqueous solutions. The orthorhombic perovskite phases of LaFeO3 and CaxLa1−xFeO3 are characterized by X-ray diffraction patterns. The sensors fabricated with those powders have high sensitivity to alcohol. Partial substitution of La3+ in LaFeO3 with Ca2+ can enhance the sensitivity of the materials to reducing gases. The resistance of an LaFeO3 sensor in air, vacuum and alcohol-containing air has been measured. Complex impedance spectroscopy has been used to try and analyse the gas-sensing mechanism. According to the experimental results, it can be deduced that the surface adsorptive and lattice oxygen govern the sensing properties of LaFeO3 and CaxLa1−xFeO3 ceramics.
115 citations
TL;DR: In this article, the authors investigated the fracture toughness of poly(styrene-co-acrylonitrile) (SAN) with 25 wt% SAN content with uncured bisphenol-A (DGEBA) type epoxy resin.
87 citations
TL;DR: This study studied the responses of 164 relay cells in layer A and A1 of the dorsal lateral geniculate nucleus (LGNd) to grating stimuli to suggest that grating adaptation is a general property, independent of cell type.
Abstract: Adaptation of visual cortical cells' responses is observed following repeated presentation of grating stimuli. Grating adaptation is believed to exist only at the cortical level. The purpose of this study was to see if grating adaptation also occurs in the lateral geniculate nucleus. We studied the responses of 164 relay cells in layer A and A1 of the dorsal lateral geniculate nucleus (LGNd) to grating stimuli. Normal cats, as well as cats in which visual cortex was ablated, were studied. Adaptation was investigated using repeated presentation of gratings of different contrasts and orientations. The results showed the following: (1) Grating adaptation reduced the responses of 46% of the LGNd cells recorded. The responses normally decreased within 30 s and then stabilized. However, there was heterogeneity in the effects observed. About 38% of the cells studied were not affected by the adapting gratings. Some cells (16%) showed facilitation rather than habituation of their responses to test stimuli. (2) There was no significant difference between X and Y cells in their susceptibility to adaptation. This suggests that grating adaptation is a general property, independent of cell type. (3) The contrast-response curves of 57% of the LGNd cells studied shifted down after exposure to high-contrast adapting gratings. (4) Adapting gratings of the cells' preferred orientation decreased the orientation sensitivity of 56% of the orientation-sensitive cells. Adapting gratings at the nonpreferred orientation did not affect orientation sensitivity. (5) Prolonged grating adaptation also reduced the responses of 49% of the LGNd cells after inactivation of cortical inputs to the LGNd.
TL;DR: In this article, a scheme for preparing Schrodinger cat states for a cavity field with controllable weighting factors is presented based on state-selective measurements on nonresonant atoms crossing the cavity.
TL;DR: In this article, numerical solutions of the two-dimensional incompressible Navier-Stokes equations using primitive variables were used to demonstrate the viability and accuracy of the method, and some basic patterns of vortex shedding can be identified according to their calculated results and are in good agreement with available experiments.
TL;DR: The results of the searches for neutral Higgs boson production in the process e + e − → Z ∗ H 0 are reported in this paper, focusing on Higgs Boson masses below 70 GeV.
TL;DR: In this article, a spring-layer model is employed to characterize the weakened interfaces, and a von Karman-type nonlinear theory is developed, taking into account the initial geometric imperfection.
Abstract: The problem of modeling elastic behavior of geometrically imperfect laminated composite plates is addressed, with particular attention paid to the effects of interfacial weakness. A spring-layer model is employed to characterize the weakened interfaces, and a von Karman-type nonlinear theory is developed, taking into account the initial geometric imperfection. The proposed theory includes the recently well-developed third-order zigzag theory as a special case. The displacement-based and mixed governing equations are shown to contain five and four unknowns, respectively. Simple numerical results are given to illustrate the effects of interfacial weakness on the buckling and bending behavior of laminated composite plates.
TL;DR: In this paper, two kinds of nano-TiO 2 samples, including nano-anatase and nano-rutile, were prepared by the hydrothermal method and the gas condensation method, respectively.
Abstract: Two kinds of nano-TiO 2 samples, including nano-anatase and nano-rutile, were prepared by the hydrothermal method and the gas condensation method, respectively. Results of dielectric measurements are as follows: 1. Nano-TiO 2 bulk samples (anatase and rutile) exhibit much higher dielectric constant than coarse-grain samples in the low measuring frequency range. 2. For both nano-anatase and nano-rutile, one peak appears in the spectrum of dielectric constant versus temperature, and it is located in the measuring temperature range of -150 to 150 °C for nano-anatase and in the measuring temperature range of 25 to 450 °C for nano-rutile. 3. For both nano-anatase and nano-rutile, in the spectrum of dielectric loss versus temperature there exists one peak. The mechanisms of the above-mentioned phenomena were discussed in detail.
TL;DR: By contour integration, it is shown that the phase operator (one of the pair of Susskind-Glogower operators) also possesses eigenkets |\ensuremath{\gamma}${〉}}_{\mathrm{*}}$, which are the dual vector of ${\mathit{e}\mathit{\^{}}}^{\mathit-i}\mathrm{\ensureMath{\varphi}}}$'s eigen kets.
Abstract: By contour integration we show that the phase operator ${\mathit{e}\mathit{\^{}}}^{\mathrm{\ensuremath{-}}\mathit{i}\mathrm{\ensuremath{\varphi}}}$ (one of the pair of Susskind-Glogower operators) also possesses eigenkets |\ensuremath{\gamma}${\mathrm{〉}}_{\mathrm{*}}$, which are the dual vector of ${\mathit{e}\mathit{\^{}}}^{\mathit{i}\mathrm{\ensuremath{\varphi}}}$'s eigenkets. The properties of |\ensuremath{\gamma}${\mathrm{〉}}_{\mathrm{*}}$ are studied and we see that |\ensuremath{\gamma}${\mathrm{〉}}_{\mathrm{*}}$ and ${\mathit{e}\mathit{\^{}}}^{\mathit{i}\mathrm{\ensuremath{\varphi}}}$'s eigenkets can also make up a phase-state representation. \textcopyright{} 1996 The American Physical Society.
TL;DR: In this article, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to obtain a uniform particle size of 70 nm for amorphous and hexagonal selenium powder.
TL;DR: The differential scattering cross sections and generalized oscillator strengths of the 1-2-2 transitions of helium have been measured by angle-resolved electron-energy-loss spectroscopy with an incident electron energy of 1500 eV and within the range of scattering angles.
Abstract: The differential scattering cross sections and the generalized oscillator strengths of the 1${\mathrm{}}^{1}$S\ensuremath{\rightarrow}2${\mathrm{}}^{1}$S and 1${\mathrm{}}^{1}$S\ensuremath{\rightarrow}2${\mathrm{}}^{1}$P transitions of helium have been measured by angle-resolved electron-energy-loss spectroscopy with an incident electron energy of 1500 eV and within the range 2\ifmmode^\circ\else\textdegree\fi{}--11.5\ifmmode^\circ\else\textdegree\fi{} of scattering angles. The corrections for angular factors and density effects have also been made for the experimental results. The differential cross sections and generalized oscillator strength values are absolute and are the first to be measured at such a high impact energy. The experimental results are compared with other measurements and theoretical calculations in the literature. \textcopyright{} 1996 The American Physical Society.
TL;DR: In this article, the first results of spectroscopic properties of X1-Y2SiO5:Eu3+ were reported, which showed that the sample under UV or dye laser excitation at room temperature exhibits a strong orange-red fluorescence.
TL;DR: In this paper, a reduced χ2 fit to the data reveals a DAZQ white dwarf with Teff = 22,500 ± 500 K, log g = 8, and photospheric abundances C = 0.5 solar, N = 5.0 solar, O = 2.2 solar, Si = 0., Fe = 0, and all other metals being 0.3 solar, with a rapidly spinning accretion belt with Vrot = 3350 km s-1, Tbelt = 26,000 ± 1000 K, and a fractional belt area
Abstract: Hubble Faint Object Spectrograph (FOS) observations of VW Hyi one day after the end of a normal dwarf nova outburst reveal a heated white dwarf with deep, broad Lyα, narrow metallic absorption features, and evidence of a hotter Keplerian-broadened component manifested in quiescence as a broad continuum hump. Our best reduced χ2 fit to the data reveals (1) a DAZQ white dwarf with Teff = 22,500 ± 500 K, log g = 8, and photospheric abundances C = 0.5 solar, N = 5.0 solar, O = 2.0 solar, Si = 0.2 solar, Fe = 0.5 solar, with all other metals being 0.3 solar, and (2) a rapidly spinning accretion belt with Vrot = 3350 km s-1, Tbelt = 26,000 ± 1000 K, log g = 6.0, and a fractional belt area of approximately 11%. Our earlier FOS spectrum obtained 10 days after superoutburst reveals a cooler DAZQ white dwarf (20,500 ± 1000 K), relatively lower metal abundances, and a smaller fractional area (3%) for the accretion belt. Thus, 1 day after a normal outburst, the white dwarf is ≈ 2000 K hotter, the accretion belt fractional area is a factor of 3 greater, the accretion belt temperature appears to be cooler than at 10 days post-superoutburst, and the accreted atmosphere has relatively higher metal abundances. Finally, the accretion belt maintained during quiescence may provide a natural explanation for the 14 s soft X-ray oscillations, requires a deeper source of heating (compression and shear mixing), and implies a lower limit to the viscous spin-down timescale of 10 days.
TL;DR: In this article, an extended X-ray absorption spectroscopy (EXAFS) was used to determine the local structure of luminescence centres in Eu 3+ doped, Eu-Bi doped and Eu Tb doped nanoscale yttrium oxide as well as Eu 2.5 + doped Eu silicate.
TL;DR: In this article, the Raman spectra of nanometer-sized Cr2O3 particles at room temperature are reported and it is shown that the correlation between the change of the spectrum and the crystal size is different from that of other nano-sized materials.
Abstract: The Raman spectra of nanometer-sized Cr2O3 particles (annealed in air and in vacuum at different temperatures) at room temperature are reported. The results show that the correlation between the change of the Raman spectrum of nanometer Cr2O3 and its crystal size is different from that of other nanometer-sized materials. It was shown that the shifting and broadening of the Raman spectra were related to the defect structures produced by an oxygen deficiency in the material and was not due to a grain size effect.
TL;DR: In this paper, the core-shell morphology of silicone rubber/polystyrene and poly(methyl methacrylate-divinyl benzene) composite particles were obtained by polymerization of vinyl monomers in the presence of crosslinked and linear poly(dimethyl siloxane-methyl vinyl Siloxane) latex.
Abstract: Silicone rubber particles with core–shell structure were prepared by polymerization of vinyl monomers in the presence of crosslinked and linear poly(dimethyl siloxane-methyl vinyl siloxane) latex. The monomers were added with either continuous or swelled-continuous addition mode. The core–shell morphology of silicone rubber/polystyrene [PST] and silicone rubber/poly(methyl methacrylate-divinyl benzene) [P(MMA-DVB)] composite particles were obtained. The effects of monomer addition mode, the compatibilities of the monomers or their homopolymer with silicone rubber, and the reactivity of polysiloxane with vinyl monomers on the formation of the core–shell structure were discussed. © 1996 John Wiley & Sons, Inc.
TL;DR: In this article, an expanded local mode approach was proposed for XY2 (C2v symmetry) molecules, based on a careful analysis of the transformation coefficients lNαλ and the properties of the intramolecular potential function.
TL;DR: In this paper, thin films of NiO (200 nm) with a preferred [lcub]110[rcub] orientation were deposited by a spray pyrolysis method.
TL;DR: In this paper, a coated fiber bundle model is proposed for tensile impact testing of glass-fibre-reinforced epoxy. But the model is not suitable for the case of high temperature and transient temperature rise.
TL;DR: In this article, the difference between consecu~ve primes was discussed and the following theorem was established: the funct ion g(x) satisfies g (x) K log log x fox* every K > 0 and x>fzo(tC) for any A > 0 ~e$
Abstract: This paper discusses two problems which relate to the difference between consecu~ve primes. Let p. be the nth prime, and d. = p . + l p . . (1) We want to find a funct ion f(,~) such that d . 0 is a given constant and cl is a number which satisfies ~*((r, T) ~O, (4) provided the funct ion g(x) satisfies g(x) K loglog x fox* every K > 0 and x>fzo(tC). This paper establishes the following theorem and so improves on the above result. Theorem 1. Suppose that the estimate (4) hoZds and the est~mata N (or, T) 0 and q'z>0. For any A > 0 ~e$
TL;DR: In this paper, the structure of hadronic events recorded by the L3 detector at center-of-mass energies of 130 and 136 GeV was studied and a comparison of the data with resummed O(alpha_s^2) QCD calculations was made.
TL;DR: In this article, a two layer ultrafiltration alumina membrane was prepared by a sol-gel process using boehmite sol as a precursor, and the results showed that the membrane thickness and surface morphology were affected by the dipping time, the viscosity and the temperature.