Size-dependent melting properties of Sn nanoparticles by chemical reduction synthesis

Tin nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent.The Sn nanoparticles smaller than 100 nm were less agglomerated and no obviously oxidized.The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry.The melting temperatures of Sn nanoparticles in diameter of 81,40,36 and 34 nm were 226.1,221.8,221.1 and 219.5？欲espectively.The size-dependent melting temperature and size-dependent latent heat of fusion have been observed.The size-dependent melting properties of tin nanoparticles in this study were also comparatively analyzed by employing different size-dependent theoretical melting models and the differences between these models were discussed.The results show that the experimental data are in accordance with the LSM model and SPI model,and the LSM model gives the better understanding for the melting property of the Sn nanoparticles.

New Easy Method for the Monitoring of Hg Concentration in Fish, Using a Nanostructured Gold Electrode

The applicability of a gold nanoparticle-modified glassy carbon sensor （AuNPs-GCS） for the determination of inorganic mercury in fresh and canned tuna fish by square wave anodic stripping voltammetry （SW-ASV） is demonstrated. Mercury content in sample Tuna Fish ISPRA T22 was determined to value the accuracy of the determination. The concentration in this sample is not certified, so, the Hg amount was determined also with atomic absorption spectroscopy （AAS）： the results obtained with ASV were in good agreement and confirmed literature value reported for this sample. Then, real samples of tuna fish were analyzed. The voltammetric analyses were performed using previously optimized conditions （deposition potential 0 V, step potential 0.004 V, frequency 150 Hz and amplitude 0.003 V）. Medium exchange technique permitted to eliminate possible matrix effects. The concentrations in the real samples were found to be in agreement with the common Hg levels reported in literature for commercialized tuna fish in different countries.

Immobilization of Hemoglobin on Cobalt Nanoparticles-modified Indium Tin Oxide Electrode： Direct Electrochemistry and Electrocatalytic Activity

A cobalt nanoparticles-attached indium tin oxide（CoNPs/ITO） electrode was applied to the immobilization of hemoglobin（Hb） and an Hb modified CoNPs/ITO electrode（Hb/CoNPs/ITO） was prepared. The direct electron transfer of Hb was shown by the well-behaved voltammetric responses for Hb/CoNPs/ITO electrode and the effects of scan rate and pH value were observed. Based on the catalytic activity of Hb immobilized on the CoNPs/ITO electrode toward the reduction of H2O2, a mediator-free H2O2 sensor was developed. A linear relationship existed between the catalytic current and the H2O2 concentration in a range of 1.0--100.0 μmol/L with a detection limit （S/N=3） of 0.2μmol/L.