Current views of drought research: experimental methods, adaptation mechanisms and regulatory strategies

Drought stress is one of the most important abiotic stresses which causes many yield losses every year. This paper presents a comprehensive review of recent advances in international drought research. First, the main types of drought stress and the commonly used drought stress methods in the current experiment were introduced, and the advantages and disadvantages of each method were evaluated. Second, the response of plants to drought stress was reviewed from the aspects of morphology, physiology, biochemistry and molecular progression. Then, the potential methods to improve drought resistance and recent emerging technologies were introduced. Finally, the current research dilemma and future development direction were summarized. In summary, this review provides insights into drought stress research from different perspectives and provides a theoretical reference for scholars engaged in and about to engage in drought research

Preparation of Pb-doped tailings-based nano-TiO2 and study on photocatalytic degradation of PAM wastewater

As an efficient flocculant, polyacrylamide (PAM) is widely used in water treatment process. The acrylamide monomer (AM) produced by depolymerization of residual PAM has been listed as a class IIA carcinogen, and its treatment is imminent. Flotation tailing (TC) was used as raw material to prepare a modified tailing matrix by alkali excitation. Nano-TiO2 was loaded onto the modified tailing matrix by hydrothermal method to prepare tailing-based nano-TiO2 composite (TiO2/TC) and Pb-doped tailing-based nano-TiO2 composite (Pb-TiO2/TC). The photocatalytic degradation properties of TC, modified coal matrix, TiO2/TC and Pb-TiO2/TC were analyzed with PAM as the target pollutant. The samples were characterized by XRD, SEM, UV-vis and BET, and the degradation products were analyzed and studied by high performance liquid chromatography-mass spectrometry. The degradation mechanism of PAM was explored. The results show that TC is irregular and the surface is rough; the surface of TiO2/TC is loose, the pore structure is obvious, and the fine tubular TiO2 is uniformly coated on the surface of modified tailings. The structure of Pb-TiO2/TC is more fluffy, and the modified coal matrix is loaded with more tubular TiO2. The band gap of TiO2/TC was 3.16 eV, and Pb2+ doping reduced the band gap of Pb-TiO2/TC to 3.08 eV. The specific surface area of TiO2 is 286.66 m2/g, the specific surface area of TiO2/TC and Pb-TiO2/TC are 360.33 m2/g and 358.54 m2/g. The higher specific surface area provides more active sites for the reaction, and the adsorption-catalytic synergistic effect significantly improves the photocatalytic efficiency. The degradation rates of PAM by TC and modified tailing matrix were 3.39% and 4.68%. The degradation rates of polyacrylamide by TiO2/TC and Pb-TiO2/TC loaded with TiO2 increased to 38.92% and 63.87%. After five cycles, the photocatalytic properties of TiO2/TC and Pb-TiO2/TC remained basically unchanged. In the degradation process of PAM, the macromolecular PAM breaks into small molecular weight PAM molecules, and further decomposes into NO3−, acrylic acid, acetamide and acetic acid

Correlation and predictive ability of sensory characteristics and social interaction in children with autism spectrum disorder

BackgroundIndividuals with autism spectrum disorder (ASD) often have different social characteristics and particular sensory processing patterns, and these sensory behaviors may affect their social functioning. The objective of our study is to investigate the sensory profiles of children with ASD and their association with social behavior. Specifically, we aim to identify the predictive role of sensory processing in social functioning.MethodsThe Short Sensory Profile (SSP) was utilized to analyze sensory differences between ASD children and their peers. The Social Responsiveness Scale (SRS) and other clinical scales were employed to assess the social functioning of children with ASD. Additionally, the predictive ability of sensory perception on social performance was discussed using random forest and support vector machine (SVM) models.ResultsThe SSP scores of ASD children were lower than those of the control group, and there was a significant negative correlation between SSP scores and clinical scale scores (P < 0.05). The random forest and SVM models, using all the features, showed higher sensitivity, while the random forest model with 7-feature factors had the highest specificity. The area under the receiver operating characteristic (ROC) curve (AUC) for all the models was higher than 0.8.ConclusionAutistic children in our study have different patterns of sensory processing than their peers, which are significantly related to their patterns of social functioning. Sensory features can serve as a good predictor of social functioning in individuals with ASD

An approved frequency tracking method in connected element interferometry

Carrier tracking loop is a basic method of frequency tracking in CEI (connected element interferometry), but the tracking error is very large or even worse at high dynamic. To solve this problem, a frequency tracking method assisted by open loop frequency estimation is proposed in this paper. First, an open-loop frequency estimation algorithm is used to estimate the frequency of signals at different moments, then, the least squares fitting method is used to estimate the corresponding dynamic parameters of different orders. Next, a local signal is generated to compensate the received signal. After eliminating most of the dynamic characteristics, the signal is fed into PLL (Frequency locked loop) and high-precision frequency tracking results can be obtained. Simulation results show that, in the condition of low SNR, the new method has higher accuracy than the method assisted by FLL (Frequency locked loop), and the processing time is shorter. When there is a two order Doppler frequency change, the open-loop assisted method can overcome the steady phase error of the PLL, and is of great significance in the applications of connected elements interferometry

Channel Modelling and Performance Analysis of the Near Space based on the DS Signal System

In order to describe the near space communication channel efficiently and analyse the the reasons that cause quality deterioration of ground-to-air communication link, design the Channel modelling program of the near space and establish the near space channel model based on the DS signal system which considers rain attenuation and multipath fading. Complete the analysis of rainfall impact on signal fading and estimate related parameters under different elevation. Set up the statistical model of multipath fading. Complete the simulation of Ka-band geostationary near space channel performance under different elevation. Draw bit error rate performance simulation curve under different weather conditions. The result of MATLAB simulation shows that the model can reflect the fading characteristic of the near space communication channel. This program improves the signal fading and interference tolerance. The findings can provide a better simulation Platform for the follow-up job according to the correctness and practicability of established model and be of great significance in exploration and research of near space communication