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Nowadays, the demand of consumers and industrial users for satellite-terrestrial integrated communications is evolving to achieve seamless coverage and anytime, anywhere access, and the integration of satellite and terrestrial communication capabilities will be the development direction of future mobile phones. The application scenarios for direct-to-handset connectivity, domestic and international development paths, and related technical solutions were introduced. Subsequently, the network architecture and key technology for realizing direct-to-handset connectivity with respect to the 3GPP NTN standard scheme were analyzed. The requirements and potential improvement schemes for multi-mode terminals in satellite communication scenarios in terms of integrated design, antenna capabilities, voice capabilities and power saving, were also identified. Finally, by exploring the key regulatory challenges (e.g. radio-frequency spectrum) related to direct-to-handset communications, feasible pathways for the future development of satellite-terrestrial integrated terminals were provided.

Heavy metal contaminants in vegetable oils can cause irreversible damage to human health. In this study, the quantitative detection of Cd in vegetable oils was investigated based on Raman spectroscopy combined with chemometric methods. The necessary preprocessing of the Raman signal was performed using baseline calibration and the Savitzky–Golay method. Three variable optimization methods were applied to the preprocessed Raman spectra. Namely, bootstrap soft shrinkage, multiple feature spaces ensemble strategy with least absolute shrinkage and selection operator, and competitive adaptive reweighted sampling (CARS), respectively. Partial least squares regression (PLSR) modeling for the determination of Cd in vegetable oils. The results show that three variable optimization algorithms improved the predictive performance of the model. Among them, the CARS–PLSR model has strong generalization performance and robustness. Its prediction coefficient of determination (RP2$R_{\mathrm{P}}^2$) was 0.9995, the root mean square error of prediction was 0.3533 mg/kg, and the relative prediction deviation was 44.3748, respectively. In summary, rapid quantitative analysis of Cd contamination in vegetable oils can be realized based on Raman spectroscopy combined with chemometrics. [ABSTRACT FROM AUTHOR]

Organic thermoelectric (TE) materials provide a brand new perspective to search for high-efficiency TE materials, due to their low thermal conductivity. The overlap of pz orbitals, commonly existing in organic π-stacking semiconductors, can potentially result in high electron mobility comparable to that of inorganic materials. Here we propose a strategy to utilize the overlap of pz orbitals to increase the TE efficiency of a layered polymeric carbon nitride (PCN). Through first-principles calculations and classical molecular dynamics simulations, we find that an A–A stacked PCN has unexpectedly high cross-plane ZT up to 0.52 at 300 K, and can contribute to n-type TE groups. The high ZT originates from its one-dimensional charge transport and low thermal conductivity. The thermal contribution of the overlap of pz orbitals is investigated, which slightly enhances the thermal transport when compared with that without considering the overlap effect. That is, there is a limited influence of orbital overlap to thermal conductivity. To explore the physical insight behind its TE advantages, we find that the low-dimensional charge transport results from strong pz-overlap interactions and the in-plane electron confinement, by comparing π-stacking carbon nitride derivatives and graphite. This study can provide guidance to search for layered materials with high cross-plane TE performance. [ABSTRACT FROM AUTHOR]

Both electron and phonon transport properties of single layer MoS2 (SLMoS2) are studied. Based on first-principles calculations, the electrical conductivity of SLMoS2 is calculated by Boltzmann equations. The thermal conductivity of SLMoS2 is calculated to be as high as 116.8 Wm(-1) K(-1) by equilibrium molecular dynamics simulations. The predicted value of ZT is as high as 0.11 at 500 K. As the thermal conductivity could be reduced largely by phonon engineering, there should be a high possibility to enhance ZT in the SLMoS2-based materials.