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The purpose of this research is to synthesize Al2O3-ZnO thick films, study the effect of doping and optical excitation on their sensing properties and introduce an…
The purpose of this research is to synthesize Al2O3-ZnO thick films, study the effect of doping and optical excitation on their sensing properties and introduce an attractive candidate for acetone detection in practice.
ZnO nanoparticles doped with Al2O3 were prepared by sol-gel method and characterized via X-ray diffraction and field-emission scanning electron microscopy. The sensing properties to acetone were investigated with an irradiation of UV. The sensing mechanism was also discussed with UV-Vis spectroscopy.
The doping of Al2O3 promoted the sensing response and stability of ZnO nanoparticles. The optimum performance was obtained by 4.96 Wt.% Al2O3-ZnO. The response to acetone (1,000 ppm) was significantly increased to 241.81, even just at an operating temperature of 64°C. It was also demonstrated that optical excitation with UV irradiation greatly enhanced the sensing response and the sensitivity can reach up to 305.14.
The sensor fabricated from 4.96 Wt.% Al2O3-ZnO exhibited excellent acetone-sensing characteristics. It is promising to be applied in low power and miniature acetone gas sensors.
In the present research, the optimum performance was obtained by 4.96 Wt.% Al2O3-ZnO at a low operating temperature of 64°C. The sensing properties were enhanced significantly with optical excitation, and the sensing mechanism was discussed with UV-Vis spectroscopy which has been reported rarely before.
The purpose of this paper is to examine whether China is still a passive price taker from the US soybean futures, or instead domestic futures market has developed certain…
The purpose of this paper is to examine whether China is still a passive price taker from the US soybean futures, or instead domestic futures market has developed certain degrees of pricing power through time. The finding helps to identify the importance of China soybean futures in the perspective of portfolio selection for international futures traders. If China soybean futures market is no longer a price taker after the subprime crisis, traders need to include it as a separate category in their portfolio.
This paper uses exponential generalized autoregressive conditional heteroskedasticity-generalized error distribution (EGARCH-GED) and generalized autoregressive conditional heteroskedasticity-generalized error distribution (GARCH-GED) models to test spillover effects between Dalian Commodity Exchange (DCE) and Chicago Board of Trade (CBOT) soybean futures. The authors divide daily samples into three subperiods based on the subprime crisis. Three research questions – whether China is still the price taker, the importance of Chinese soybean futures in international futures portfolio selection, and the influences of subprime crisis on soybean futures volatility relationship – are examined by comparing estimation results through time and different contracts.
The spillover effect from CBOT soybean futures to DCE No. 1 soybean futures becomes weaker through time. China is no longer a soybean futures price taker after the subprime crisis. The authors also find the shocks of bearish news on DCE soybeans are greater than those of bullish news. Potential volatility of DCE in long positions is bigger than that in short positions.
China is the largest soybean importer. DCE is a very important futures market for non-genetically modified soybeans. It is necessary for both international and domestic futures traders to understand the changes in international soybean futures price relationship and take corresponding strategies. It is also important for market to realize that DCE soybean futures are to a less degree price taker after the subprime crisis.
The paper applies EGARCH-GED and GARCH-GED models to identify changes in spillover effects before, during, and after the subprime crisis. Different from other studies, this paper finds after the subprime crisis, China is no longer the soybean futures price taker. This paper also compares the spillover effects of non-genetically modified soybean futures (No. 1 soybean futures) with genetically modified soybean futures (No. 2 soybean futures).