Nano-Ag particles/polyacrylamide （PAM） composites were synthesized by γ irradiation method and then blended with ethylene vinyl acetate （EVA）. Dielectric behaviors of the Ag/PAM/EVA composites are investigated as...Nano-Ag particles/polyacrylamide （PAM） composites were synthesized by γ irradiation method and then blended with ethylene vinyl acetate （EVA）. Dielectric behaviors of the Ag/PAM/EVA composites are investigated as a function of both the concentration and size of Ag particles. When concentration of the Ag fillers is rarely low, dielectric anomalies were first observed in contrast to the traditional percolation theory. As concentration of Ag increases, volume resistivity and breakdown field strength are enhanced, loss tangent （tan δ） reduced and dielectric constant kept invariable. In addition, the above variation became larger when the diameter of the Ag nano-particles is smaller. Such dielectric anomalies may be understood by considering the unique ＂Coulomb Blockade Effect＂ of the nano-sized Ag particles.展开更多
Carboxylic acid-functionalized nano-sized magnetic composite polymers (COOH-NMPs) were synthesized and used for the preparation of the modified glassy carbon electrode, i.e., COOH-NMPs/GCE and DNA/COOH-NMPs/GCE. The e...Carboxylic acid-functionalized nano-sized magnetic composite polymers (COOH-NMPs) were synthesized and used for the preparation of the modified glassy carbon electrode, i.e., COOH-NMPs/GCE and DNA/COOH-NMPs/GCE. The electrochemical behaviors of melamine (MM) were investigated on COOH-NMPs/GCE by cyclic voltammetry (CV) in both cases of DNA in the solution and immobilized on the electrode surface. The electron transfer coefficient (a) and the rate constant (ks) kept unchanged in the absence and presence of DNA. Based on the electrochemical properties of the interaction of MM on the surface of the DNA/COOH-NMPs/GCE, a direct method for the determination of MM in liquid milk was established. The detection limit of this method was 2.0 ng·L﹣1, with average recoveries at 95.9% - 104.2% and RSD at 4.5% - 8.2%. The proposed method was provided to have a good accuracy, high stability and good reproducibility with a simple and environmental friendly process. 10 kinds of liquid milk samples bought from the market randomly were tested, and only 1 of them was found at relatively low level of MM residue with the amount of 0.12 ug·L﹣1.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No.50277029） .
文摘Nano-Ag particles/polyacrylamide （PAM） composites were synthesized by γ irradiation method and then blended with ethylene vinyl acetate （EVA）. Dielectric behaviors of the Ag/PAM/EVA composites are investigated as a function of both the concentration and size of Ag particles. When concentration of the Ag fillers is rarely low, dielectric anomalies were first observed in contrast to the traditional percolation theory. As concentration of Ag increases, volume resistivity and breakdown field strength are enhanced, loss tangent （tan δ） reduced and dielectric constant kept invariable. In addition, the above variation became larger when the diameter of the Ag nano-particles is smaller. Such dielectric anomalies may be understood by considering the unique ＂Coulomb Blockade Effect＂ of the nano-sized Ag particles.
文摘Carboxylic acid-functionalized nano-sized magnetic composite polymers (COOH-NMPs) were synthesized and used for the preparation of the modified glassy carbon electrode, i.e., COOH-NMPs/GCE and DNA/COOH-NMPs/GCE. The electrochemical behaviors of melamine (MM) were investigated on COOH-NMPs/GCE by cyclic voltammetry (CV) in both cases of DNA in the solution and immobilized on the electrode surface. The electron transfer coefficient (a) and the rate constant (ks) kept unchanged in the absence and presence of DNA. Based on the electrochemical properties of the interaction of MM on the surface of the DNA/COOH-NMPs/GCE, a direct method for the determination of MM in liquid milk was established. The detection limit of this method was 2.0 ng·L﹣1, with average recoveries at 95.9% - 104.2% and RSD at 4.5% - 8.2%. The proposed method was provided to have a good accuracy, high stability and good reproducibility with a simple and environmental friendly process. 10 kinds of liquid milk samples bought from the market randomly were tested, and only 1 of them was found at relatively low level of MM residue with the amount of 0.12 ug·L﹣1.
