Distinctive terahertz (THz) absorption spectra of ninhydrin and indane-1,2,3-trione ranging from 0.5 to 4.5 THz were observed firstly in our experiment by terahertz time-domain spectroscopy (THz-TDS). The dehydration process of ninhydrin was also monitored online. The experimental results indicate that THz spectroscopy is highly sensitive to the crystal structure, weak intermolecular interactions, and the environmental change. Multitechniques including differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) were also carried out to further investigate ninhydrin and indane-1,2,3-trione. And the results support the reliability of THz spectroscopy. Density functional theory (DFT) calculations based on the samples’ crystalline structures were performed for better understanding the THz characteristic spectra. The calculations agree with the experimental observation, and the corresponding vibrational modes of ninhydrin and indane-1,2,3-trione are assigned.
To check students’ daily language learning tasks and give students corresponding reasonable scores based on their daily behavior is hard for teachers. The existing online language learning systems are vulnerable and easy to be modified by teachers or system managers. Blockchain can provide immutable and trusted storage service and automatic calculation service. Therefore, a blockchain-based online language learning system is proposed in this paper to monitor students’ daily study and automatically evaluate their behavior so as to save teachers from tedious and complex homework verification workload and provide trusted and reliable evaluation on students’ behavior. This paper first introduces the current situation of language learning in universities and the related works on blockchain-based online language learning system. Then the system is detailed in its structure and smart contracts. At last, we implement this system and do the analysis and summary.
An equivalent circuit model of a pixellated-metal-mirror ferroelectric liquid crystal (FLC) optically addressed spatial light modulator (OASLM) is proposed. Using both structure and FLC material parameters of a real device and real material as the simulation parameters, the model is firstly confirmed by good agreement of simulation results and the reported experimental ones, and then utilized to optimize gray-scale performance of the OASLM. The model is developed from an improved FLC equivalent circuit, and has the ability to describe the voltage dropped across the modulating layer and to predict how optical outputs vary over time with the input drive voltage and control image. Simulation results indicate that gray-scale performance of the OASLM is highly dependent on write pulse width. More than 10 gray scales are observed when write pulse width is 100 μs and the number reduces to four when it reaches 500 μs. Other parameters of drive voltage can be set to adjust the region of write light intensity over which gray scales are best produced, and write pulses are found to be primary at high write light intensities, whereas erase pulses are dominant at low write light intensities. Furthermore, although gray-scale performance is weakly dependent on erase-light intensity, the erase light is necessary to ensure a proper erasure of the device and at least 1 mW/cm2 is required in this study. 相似文献
