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NanShan District of Shenzhen, China

Lu B.,Japan National Institute of Environmental Studies | Li Z.,Shenzhen Academy of Metrology and Quality Inspection | Kawamoto K.,Japan National Institute of Environmental Studies
Materials Research Bulletin | Year: 2013

The synthesis of mesoporous ceria (CeO2) without a template was studied in detail using NaOH and NH4OH solution. We first synthesized nanosized mesoporous CeO2 without a template by the direct hydrothermal synthesis method with NaOH. By using NaOH, mesoporous CeO 2 could be obtained without a template through the oxidation of Ce3+ ions, the hydrolysis of Ce4+ ions, polymerization and precipitation. Under appropriate synthesis conditions, the obtained mesoporous CeO2 had a high surface area, a narrow pore size distribution and an ordered structure with uniform mesopores. The surface area of the mesoporous CeO2 increased with increasing synthesis temperature. The NaOH concentration induced different behavior on the mesoporous CeO2 surface with and without a template. The mesoporous CeO2 had nanoarrays with uniform mesopores (intercrystalline voids). However, when NH4OH solution was used, the CeO2 had nanoarrays with a hierarchical pore network. The mesoporous CeO2 obtained without template had relatively high thermal stability that increased with increasing synthesis temperature. © 2013 Elsevier Ltd. All rights reserved.

Chen Z.,Guilin University of Technology | Li Y.,Shenzhen Academy of Metrology and Quality Inspection | Lin S.,Hong Kong Baptist University | Wei M.,Guilin University of Technology | And 2 more authors.
Biochemical and Biophysical Research Communications | Year: 2014

In this study, an easy and efficiency protein digestion method called continuous microwave-assisted protein digestion (cMAED) with immobilized enzyme was developed and applied for proteome analysis by LC-MSn. Continuous microwave power outputting was specially designed and applied. Trypsin and bromelain were immobilized onto magnetic micropheres. To evaluate the method of cMAED, bovine serum albumin (BSA) and protein extracted from ginkgo nuts were used as model and real protein sample to verify the digestion efficiency of cMAED. Several conditions including continuous microwave power, the ratio of immobilized trypsin/BSA were optimized according to the analysis of peptide fragments by Tricine SDS-PAGE and LC-MSn. Subsequently, the ginkgo protein was digested with the protocols of cMAED, MAED and conventional heating enzymatic digestion (HED) respectively and the LC-MSn profiles of the hydrolysate was compared. Results showed that cMAED combined with immobilized enzyme was a fast and efficient digestion method for protein digestion and microwave power tentatively affected the peptide producing. The cMAED method will be expanded for large-scale preparation of bioactive peptides and peptide analysis in biological and clinical research. © 2014 Elsevier Inc. All rights reserved.

Liu X.-Q.,Zhengzhou University | Li Z.-Y.,Shenzhen Academy of Metrology and Quality Inspection | Yuan X.-J.,Zhengzhou University | Wu B.-L.,Zhengzhou University
Journal of Coordination Chemistry | Year: 2012

A purine-containing multifunctional ligand, 2-(6-oxo-6H-purin-1(9H)-yl) acetic acid (HL), and two new 2-D coordination polymers, [Co(L) 2(H 2O) 2] n2nH 2O (1) and [Ni(L) 2(H 2O) 2] n2nH 2O (2), were synthesized and characterized. Polymers 1 and 2 have isomorphous structures with (4,4)-connected topologies composed of left- and right-handed metal-organic helices sharing common metal centers. Two helical conformations in the same net are stabilized by strong π-π stacking interactions between purine groups. Through direct and water-mediated interlayer hydrogen-bond interactions those layers are assembled into stable 3-D supermolecules where slight differences in the strength of hydrogen bonds and coordination bonds result in their decomposition behaviors. © 2012 Taylor and Francis.

Li Q.,Shenzhen Academy of Metrology and Quality Inspection | You J.,Hong Kong Polytechnic University | Zhang D.,Hong Kong Polytechnic University
Expert Systems with Applications | Year: 2012

Automated segmentation of blood vessels in retinal images can help ophthalmologists screen larger populations for vessel abnormalities. However, automated vessel extraction is difficult due to the fact that the width of retinal vessels can vary from very large to very small, and that the local contrast of vessels is unstable. Further, the small vessels are overwhelmed by Gaussian-like noises. Therefore the accurate segmentation and width estimation of small vessels are very challenging. In this paper, we propose a simple and efficient multiscale vessel extraction scheme by multiplying the responses of matched filters at three scales. Since the vessel structures will have relatively strong responses to the matched filters at different scales but the background noises will not, scale production could further enhance vessels while suppressing noise. After appropriate selection of scale parameters and appropriate normalization of filter responses, the filter responses are then extracted and fused in the scale production domain. The experimental results demonstrate that the proposed method works well for accurately segmenting vessels with good width estimation. © 2012 Elsevier Ltd. All rights reserved.

Liu C.,Harbin Engineering University | Ji Z.,Harbin Engineering University | Xu H.,Shenzhen Academy of Metrology and Quality Inspection
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2012

The three-dimensional time-domain computational fluid dynamics (CFD) approach is employed to compute the acoustic attenuation performance of perforated tube silencers with flow. For both cases with and without impulse signal imposed at the inlet of silencer, the time histories of the pressures at the upstream and downstream monitors of the silencer can be obtained through the unsteady calculations. The differences between two computational results at the same monitor are the impulse signal and corresponding reflective signal. The acoustic pressures in time domain are then transformed to the frequency domain by using the Fast Fourier Transform, and the transmission loss of silencer may be determined. The transmission loss of the straight-through perforated tube silencers and cross-flow perforated tube silencer is calculated using this method. The numerical predictions are compared with the experimental measurements and the calculated results from the frequency domain approach, which show that the three-dimensional time-domain CFD approach could predict accurately the acoustic attenuation performance of perforated tube silencers. Finally, the effects of gas flow velocity and temperature on the transmission loss of cross-flow perforated tube silencer are analyzed. The mean flow shifts the transmission loss curve to the lower frequency and increases the transmission loss in many frequencies. The transmission loss curve is moved to the higher frequency as the temperature increases. © 2012 Journal of Mechanical Engineering.

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