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111.
Jong Hyun Bae 《Applied Surface Science》2007,253(9):4150-4155
Surface functionalization of single-walled carbon nanotube was carried out by introducing ylides groups containing anchored phenol structures. The functionalized nanotube is characterized using elemental analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis, Raman spectroscopy and zeta potential measurements. Elemental and FT-IR analysis reveal the successful functionalization of azomethine ylides. Raman spectroscopic studies corroborates that the surface functionalization does not affect the basic crystal domain size of the nanotubes. Functionalized carbon nanotubes exhibit higher zeta potential values showing its higher dispersant ability in water and acetone solvent in comparison to pure carbon nanotube. 相似文献
112.
Silicic acid high purity was produced by passing sodium silicate solution under pressure through a column packed with ion exchange resin. The effect of sodium chloride concentration on the gel formation process was studied. We proposed that, besides amorphous sol, chain-like compounds were also formed in the silicic acid gelatinization process. Polysilicic acid solution was obtained by slow polymerization of the silicic acid at lower temperature. Some organic solvents were added to this solution at room temperature, resulting in a novel material species - partial crystallized polysilicic acid powder. Characterization techniques such as XRD, IR, TEM, TGA and DTA were used to investigate the materials. The new findings in the present study supported the previously proposed mechanism for silicic acid chain polymerization. 相似文献
113.
Formation of Co germanosilicides on Si0.8Ge0.2 virtual substrates with a Co/Au/Co sandwich thin film after different heat treatments has been investigated. The sequence of phase formation is the same as the reaction of blanket Co thin film with (001)Si. The presence of thin interposing Au layers was found to significantly enhance the formation of low-resistivity CoSi2 on (001)Si0.8Ge0.2 substrates. The formation temperature of CoSi2 phase in the Co/Au/Co/(001)Si0.8Ge0.2 samples was lowered by about 200 °C compared to that of Co/(001)Si0.8Ge0.2 samples. From TEM and EDS analysis, some of Au atoms were found to diffuse from the original interface position to disperse within the CoSi2 layers during silicidation reactions. The mechanisms for the enhanced formation of CoSi2 in the Co/Au/Co/Si0.8Ge0.2 system were explained in the context of classical nucleation theory. 相似文献
114.
E. Dietrich A. Lucas-Girot Y. Le Gal S. Jeanne G. Cathelineau 《Applied Surface Science》2008,255(2):391-395
Bioactive glasses in the system SiO2-CaO-Na2O-P2O5 were synthesized pure and doped with magnesium or zinc by melt-derived method. The bioactivity was studied during in vitro assays: the ability of hydroxycarbonate apatite (HCA) layer to form on the glass surface was examined after contact with simulated body fluid (SBF). The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies were performed before and after immersion in vitro assays. The SBF solutions were also analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES).Introduction of magnesium and zinc as trace element induces several modifications on the observed phenomena at the glass surface and in SBF solution after immersion of the samples. The chemical durability of the glasses, the formation of the silica-rich layer and the crystallization of the HCA layer were affected, but not present the same modifications as the introduced doping element. 相似文献
115.
Scaling approach of the convective drying of a porous medium 总被引:1,自引:0,他引:1
P. Coussot 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(3):557-566
We propose a simplified, theoretical approach of the evolution of liquid distribution during the convective drying of a granular
packing. In the absence of gravity effects three regimes are distinguished according to the relative importance of surface
evaporation, capillarity or evaporation from the interior of the sample. The evolution of the drying rate as a function of
the saturation can be inferred from the characteristic velocities associated to each of these effects. We also carried out
drying experiments of bead packings saturated with ethanol, at four different velocities of the boundary convection current,
and with bead size ranging from 4.5 to 100 μm. The drying curves exhibit different regimes with a scaling as a function of
particle radius and current velocity as predicted by the theory.
Received 7 June 1999 and Received in final form 25 October 1999 相似文献
116.
F. Kokai M. Taniwaki M. Ishihara Y. Koga 《Applied Physics A: Materials Science & Processing》2002,74(4):533-536
We deposited amorphous thin films of boron carbide by pulsed laser deposition using a B4C target at room temperature. As the laser fluence increased from 1 to 3 J/cm2, the number of 0.25–5 μm particulates embedded in the films decreased, and the B/C atomic ratio of the films increased from
1.8 to 3.2. The arrival of melt droplets, atoms, and small molecular species depending on laser fluence appeared to be involved
in the film formation. In addition, with increasing fluence the nanoindentation hardness of the films increased from 14 to
32 GPa. We believe that the dominant factor in the observed increase in the films’ hardness is the arrival of highly energetic
ions and atoms that results in the formation of denser films.
Received: 23 March 2001 / Accepted: 1 July 2001 / Published online: 2 October 2001 相似文献
117.
E.V. Astrova T.S. Perova S.A. Grudinkin V.A. Tolmachev V.A. Melnikov 《Journal of luminescence》2006,121(2):298-300
The paper reports on composite periodic structures fabricated by means of wet anisotropic etching of (1 1 0)-oriented Si on a SOI platform and infiltrated with liquid crystal E7. The electro-optical effect under low voltages was registered for inter-digital structures by both optical microscopy and micro-Raman spectroscopy. 相似文献
118.
Test of Determination of (p,γ) Astrophysical S-Factors Using the Asymptotic Normalization Coefficients from Neutron Transfer Reactions
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The asymptotic normalization coefficients (ANCs) for the virtual decay ^17 O→^16 O+n are derived from the angular distributions of the 16 O(d, p)^17O reaction leading to the ground and first excited states of ^17O, respectively, using the distorted wave Born approximation and the adiabatic wave approximation. The ANCs of ^17F are then extracted according to charge symmetry of mirror nuclei and used to calculate the astrophysical S-factors of ^16 O(p, γ)^17 F leading to the first two states of ^17 F. The present results are in good agreement with those from the direct measurement. This provides a test of this indirect method to determine direct astrophysical S-factors of (P, γ) reaction. In addition, the S-factors at zero energy for the direct captures to the ground and first excited states of ^17 F are presented, without the uncertainty associated with the extrapolation from higher energies in direct measurement. 相似文献
119.
The spinel NiCo2O4 nanofibers with diameters of 50-100 nm were prepared by high temperature calcinations of a simple inorganic-polymer composite fibers, which were obtained by electrospinning of the PVA/cobalt acetate/nickel acetate composite precursor. The crystallinity, purity, and surface morphology of the as-prepared NiCo2O4 nanofibers were investigated by XRD, FT-IR, SEM, respectively. 相似文献
120.
We perform a first-principles study on the electronic structure and elastic properties of TiaA1C with an antiperovskite structure. The absence of band gap at the Fermi level and the finite value of the density of states at the Fermi energy reveal the metallic behavior of this compound. The elastic constants of Ti3AlC are derived yielding c11 = 356 GPa, c12 = 55 GPa, c44 = 157 GPa. The bulk modulus B, shear modulus G and Young's modulus E are determined to be 156, 151 and 342 GPa, respectively. These properties are compared with those of Ti3AlC2 and Ti2AlC with a layered structure in the Ti-Al-C system and FeaAlC with the same antiperovskite structure. 相似文献