Novel Fabrication of High-Quality ZrO2 Ceramic Thin Films from Aqueous Solution

We report on the direct deposition of high-quality ZrO₂ thin films on various kinds of substrates by the liquid phase deposition method. After reaction for 24 h, thin films formed on various kinds of substrates, and the obtained thin film was comprised of densely packed nano-sized particles. The film annealed at 500°C showed a tetragonal phase at room temperature and this phenomenon has been discussed from the viewpoint of crystallite size effect. The result of optical transmittance measurement revealed that high transparency, more than 70% transmittance, has been achieved for the film after annealing at 900°C.     

Electromechanical Properties of Porous Piezoelectric Ceramics

A theoretical approach is forwarded to predict the electromechanical properties of porous piezoelectric ceramics. The analysis is able to account for the effects of porosity shape and concentration and is applicable to piezoelectric ceramics of arbitrary material symmetry. By coupling the exact solution for a single ellipsoidal pore embedded in an infinite piezoelectric matrix with an effective medium approximation, the theory considers, in an approximate manner, interaction effects at finite porosity concentrations. The theoretical estimates are developed using a matrix formulation which enables all elastic, dielectric, and piezoelectric moduli of the porous solid to be readily computed. Numerical results are presented to illustrate the effects of the shape and concentration of the porosity on the effective electroelastic moduli and transducer parameters of practical importance. Particular attention is devoted to assessing the sensitivity of the effective electromechanical properties to the accuracy of the input data. Finally, theoretical estimates are shown to be in good agreement with existing experimental results for porous piezoelectric ceramics with various microstructural geometries.     

Low-Temperature Synthesis of NaNbO3 Nanopowders and their Thin Films from a Novel Carbon-Free Precursor

We have demonstrated a synthetic procedure for nano-sized NaNbO₃ powder and its thin films using a carbon-free precursor prepared by the reaction of H₂O₂ with sodium and niobium alkoxides. A combination of X-ray powder diffraction, Raman spectra, and thermal gravity and differential thermal analysis, carbon analysis, fourier transform infrared spectra, transmission electron microscopy, and atomic force microscopy was used to characterize the resulting materials and precursor compounds. Results show that this procedure demonstrates the major advantages of low-temperature synthesis (∼400°C) and low weight loss during transformation into NaNbO₃ because of its carbon-free nature, which also provides the option of preparing nano-sized particles and dense, crack-free NaNbO₃ thin films.     

The effect of the addition of silica particles on linear spherulite growth rate of isotactic polypropylene and its explanation by lamellar cluster model

The effect of the addition of silica particles on spherulite growth rates of isotactic polypropylene has been investigated using an optical microscope. The spherulite growth rate remained constant with time and the growth rates decreased with increasing the silica content. The addition of silica particles generally causes a reduction of the average distance between adjacent silica particles and the linear growth rates become zero when the inter-particle distance reached to the end-to-end distance of the matrix chains. The reduction in the linear growth rate can be explained by assuming the lamellar clustering process that the precursor or solidified units with the single chain space, which spontaneously are built up from the melt, act as the crystallizing units and the diffusive mobility of the units was restricted by spatial confinement between adjacent silica particles.     

Annealing effects of a high-quality ZnTe substrate

The sharp photoluminescence (PL) and optical-reflection spectra in the bandedge region of the high-quality nondoped ZnTe substrate (100) were observed at 4.2 K. Free exciton, associated with lower and upper polaritons (EX^L and EX^U) at 2.382 eV and 2.381 eV, respectively, were clearly observed. This meant that this substrate was high quality. The intensity of a bound exciton peak (2.375 eV), which is caused by a Zn vacancy, of a neutral acceptor decreased with an increase of the Zn vapor pressures.     

Plausible guard effect on the active sites of heterogeneous Ziegler–Natta catalyst by coordinating monomers and growing polymer chains in the initial stage of propene polymerization

Investigation of propene polymerization by a modified stopped‐flow technique using TiCl₄/ethylbenzoate(EB)/MgCl₂ Ziegler–Natta catalyst with or without pretreating the catalyst with triethylaluminium (TEA) within an ultra‐short period (ca 1 s) was conducted to gain new understanding of the nature of active sites related to TEA in the early stage of polymerization. When the catalyst was pretreated by a cocatalyst, deactivation behaviour was clearly observed, even within an extremely short pretreatment period. In contrast, without pretreatment, the deactivation of active sites can be neglected within the polymerization period indicating that the activated Ti species might be protected from deactivation by TEA when monomer is present in the system. A plausible guard effect on the active sites by coordinating monomer and growing polymer chains in the initial stage of polymerization is proposed to account for this phenomenon. Copyright © 2004 Society of Chemical Industry     

Digit recognition in a natural scene with skew and slant normalization

This paper proposes a method to recognize digits in a natural scene, such as telephone numbers on a signboard. Candidate regions of digits are extracted from an image through contrast enhancement, edge extraction, and labeling. Since the target text patterns are in a 3D space, unlike traditional character recognition problems, we have to deal with the image transformation effect due to the orientation in the 3D space and projection. We have to cancel the effect as much as possible before digit recognition. In our method, the image transformation effect is modeled as skew and slant. In the proposed method, simplified Hough transform is used for the skew normalization. After the skew normalization, the remaining effect of image transformation is corrected by circumscribing digit patterns with tilted rectangles and affine transformation. In experiments, we tested a total of 1,332 images of signboards with 11,939 digits. We obtained a digit extraction rate of 99.2% and a correct digit recognition rate of 98.8%.Received: 15 December 2003, Accepted: 21 October 2004, Published online: 2 February 2005     

Small epitope‐linker modules for PCR‐based C‐terminal tagging in Saccharomyces cerevisiae

PCR‐mediated gene modification is a powerful approach to the functional analysis of genes in Saccharomyces cerevisiae. One application of this method is epitope‐tagging of a gene to analyse the corresponding protein by immunological methods. However, the number of epitope tags available in a convenient format is still low, and interference with protein function by the epitope, particularly if it is large, is not uncommon. To address these limitations and broaden the utility of the method, we constructed a set of convenient template plasmids designed for PCR‐based C‐terminal tagging with 10 different, relatively short peptide sequences that are recognized by commercially available monoclonal antibodies. The encoded tags are FLAG, 3 × FLAG, T7, His‐tag, Strep‐tag II, S‐tag, Myc, HSV, VSV‐G and V5. The same pair of primers can be used to construct tagged alleles of a gene of interest with any of the 10 tags. In addition, a six‐glycine linker sequence is inserted upstream of these tags to minimize the influence of the tag on the target protein and maximize its accessibility for antibody binding. Three marker genes, HIS3MX6, kanMX6 and hphMX4, are available for each epitope. We demonstrate the utility of the new tags for both immunoblotting and one‐step affinity purification of the regulatory particle of the 26S proteasome. The set of plasmids has been deposited in the non‐profit plasmid repository Addgene ( http://www.addgene.org ). Copyright © 2009 John Wiley & Sons, Ltd.