RESUMO
One of the main challenges for advanced metallic nanoparticles (NPs) supported functional perovskite catalysts is the simultaneous achievement of a high population of NPs with uniform distribution as well as long-lasting high performance. These are also the essential requirements for optimal electrode catalysts used in solid oxide fuel cells and electrolysis cells (SOFCs and SOECs). Herein, we report a facile operando manufacture way that the crystal reconstruction of double perovskite under reducing atmosphere can spontaneously lead to the formation of ordered layered oxygen deficiency and yield segregation of massively and finely dispersed NPs. The real-time observation of this emergent process was performed via an environmental transmission electron microscope. Density functional theory calculations prove that the crystal reconstruction induces the loss of coordinated oxygen surrounding B-site cations, serving as the driving force for steering fast NP growth. The prepared material shows promising capability as an active and stable electrode for SOFCs in various fuels and SOECs for CO2 reduction. The conception exemplified here could conceivably be extended to fabricate a series of supported NPs perovskite catalysts with diverse functionalities.
RESUMO
In this work, within the framework of an inhomogeneous wave, we study the wave transmission at the boundary between air and a lossy extrinsic semiconductor of n-type indium antimonide. Transmission properties such as negative refraction are specifically investigated. The choice of such a semiconductor enables us to study the tunable features in the negative refraction because its permittivity is a function of the frequency, the temperature, and the doping concentration. It is found that there exist a threshold temperature and a threshold frequency in order to obtain the negative refraction. The dependence of threshold temperature on the doping concentration and the operating frequency will be numerically demonstrated. The analysis of negative refraction can be used to study the electromagnetic response for a lossy and extrinsic semiconductor.
RESUMO
OBJECTIVE: To explore the effects of traffic exhausts on children's neurobehavioral functions. METHODS: A field study was conducted in Quanzhou, Fujian province where two primary schools were chosen based on the numbers of automobiles passing by,and the data of ambient air pollutants from the monitoring system. School B and School A located at the high traffic exhausts pollution area and the clear area, respectively. Neurobehavioral functions of pupils in grade 2 and 3 were scored. RESULTS: School B had very similar score of Ruiwen Test with School A, while the score of Digit Eras Test was lower than that in School A with marginal significance. The scores of Digit Symbol,Aim Tracing, Sign Register and Cormect Number test were 38.5 +/- 9.96, 84.3 +/- 27.83, 37.4 +/- 11.62 and 17.1 +/- 5.88 in School B,respectively, which were significantly lower than those in School A (41.6 +/- 12.97, 95.5 +/- 35.80, 42.3 +/- 15.58 and 18.7 +/- 5.78) respectively. Scores in Digit Symbol,Aim Tracing,Sign Register and Cormect Number of pupils in School B were 2.9, 11.5, 5.6 and 1.6 lower than those in School A after adjusting on other confounding factors. CONCLUSION: It was suggested that traffic exhausts might cause damage to children's neurobehavioral functions.
