Meizhouwan Vocational Technology College

Putian, China

Meizhouwan Vocational Technology College

Putian, China

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Xu Z.,Guangdong University of Technology | Xu Z.,Meizhouwan Vocational Technology College | Wu F.,Guangdong University of Technology | Guo Z.,Guangdong University of Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2012

The low frequency phononic band structures of two-dimensional arc-shaped phononic crystals (APCs) were studied by the transfer matrix method in cylindrical coordinates. The results showed the first phononic band gaps (PBGs) of APCs from zero Hz with low modes. Locally resonant (LR) gaps were obtained with higher-order rotation symmetry, due to LR frequencies corresponding to the speeds of acoustic waves in the materials. These properties can be efficiently used in a structure for low frequencies that are forbidden, or in a device that permits a narrow window of frequencies. © 2012 Elsevier B.V. All rights reserved.


Xu Z.,Guangdong University of Technology | Xu Z.,Meizhouwan Vocational Technology College | Wu F.,Guangdong University of Technology | Guo Z.,Guangdong University of Technology
Modern Physics Letters B | Year: 2012

We have studied the compression (P) wave band structures at a low frequency in two-dimensional solidsolid phononic crystals. The plane-wave expansion method based on the decomposition of elastic waves was used. The pressure field distribution of P-wave localized modes at Γ points in the lowest bands, including multiple flat bands of systems comprising different configurations, were analyzed. The results show that a lower symmetry of the scatterer are an effective method to enhance the localization of vibration modes. The property has potential applications in the design of waveguides. © 2012 World Scientific Publishing Company.


Xu Z.,Guangdong University of Technology | Xu Z.,Meizhouwan Vocational Technology College | Wu F.,Guangdong University of Technology | Guo Z.,Guangdong University of Technology
Solid State Communications | Year: 2013

The shear-wave (S-wave) band structure of a two-dimensional phononic crystals (PCs) was studied. The PCs consist of lead cylinders in a magnetorheological elastomer matrix with square lattice. Numerical results showed that S-wave band gaps can be obtained and tuned as frequency-selective filters by application of an external contactless magnetic field. This magnetic field can be rotated or possesses a variable magnitude. These approaches can be potentially applied in the design of S-wave band gap-tunable devices. © 2012 Elsevier Ltd.


Xu Z.,Guangdong University of Technology | Xu Z.,Meizhouwan Vocational Technology College | Wu F.,Guangdong University of Technology | Guo Z.,Guangdong University of Technology
Guangxue Xuebao/Acta Optica Sinica | Year: 2012

By using the plane-wave expansion method, the effect of point group symmetry on irreducible Brillouin zone in two-dimensional photonic crystals is studied. Additional cylinder in unit cell of single-cylinder two-dimensiional photonic crystal is designed as symmetrical structures with different operation numbers of symmetry, eigen-frequencies of the five lowest energy bands in the Brillouin zone are calculated. The results show that in the calculation of two-dimensional photonic crystal band structure, if the photonic crystal point group symmetry operation number is n, the irreducible Brillouin zone should be 1/n of the whole first Brillouin zone.


Yang H.,Xiamen University | Yang H.,Meizhouwan Vocational Technology College | Lin L.,Xiamen University | Odoom-Wubah T.,Xiamen University | And 4 more authors.
Separation and Purification Technology | Year: 2014

In this paper, a microorganism-mediated, cetyltrimethylammonium bromide (CTAB)-directed (MCD) aggregation of Au nanostructures around Escherichia coli cells (ECCs) for enhanced Au recovery, from aqueous HAuCl4 is demonstrated for the first time. Owing to the coordination of cell-CTAB-ascorbic acid (AA), one dimensional Au nanostructures grew around the ECCs, inducing the rapid aggregation of Au and the ECCs. The concentrations of CTAB and AA had insignificant effect on the precipitation if the ECC dosage and HAuCl 4 concentration were matched. The Au recovery efficiency decreased with increasing CTAB concentration, while a minimum AA concentration was required for higher Au recovery efficiency. The ECC-binding Au ions were reduced to form Au nuclei over the cell surface that provided preferential nucleation sites. Meanwhile, the free ligand-substituted anions in the solution were reduced to Au atoms that served as Au source for growing the Au nanostructures around the ECCs. This work exemplifies a new avenue to enhance the efficiency of recovering Au through the engineering of Au nanostructures. © 2014 Elsevier B.V. All rights reserved.


Yang H.,Xiamen University | Yang H.,Meizhouwan Vocational Technology College | Du M.,Xiamen University | Odoom-Wubah T.,Xiamen University | And 4 more authors.
Journal of Chemical Technology and Biotechnology | Year: 2014

BACKGROUND: The facile use of microorganisms as green templates for shape-control of Au nanostructures can not only utilize their characteristic nanoscale dimensions and versatility, but also bridge the gap between bulk materials and Au nanostructures for technical applications. RESULTS: Using Escherichia coli cells (ECCs), closely packed, hierarchically branched, chemically difficult-to-synthesize and stable Au nanowires (AuNWs) were fabricated through a seedless microorganism-mediated, hexadecyltrimethylammonium bromides (CTAB)-directed method. The ECCs played dual roles in the biosorption of Au ions and acted as preferential nucleation sites for Au nanocrystals in the formation of the AuNWs. In addition, proper CTAB concentration and just a little excessive ascorbic acid were essential to the formation of the AuNWs. The preferential nucleation sites that were simultaneously mediated by adjacent cells favored branched growth. Random growth of the same nanowire with multiple branched points gave rise to hierarchically branched AuNWs. Interestingly, the AuNW/ECC nanocomposites exhibited a noticeable absorbance at around 1900 nm in the near-infrared (NIR) region. CONCLUSION: This study verifies the general strategy by combining a microorganism and CTAB for the fabrication of functional AuNW/microorganism nanocomposites. © 2013 Society of Chemical Industry.

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