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With the large-scale application of composite materials in aircraft structures, the threat of visually invisible damage such as internal delamination of composite materials caused by impact from foreign objects is increasing,therefore, impact event monitoring and impact location identification of composite reinforced structures is essential.In order to verify the engineering validity of the impact localization algorithm, based on the piezoelectric sensing signal of the impact test on the composite large wall plate structure, the localization accuracy of the time-reversal focusing,error function and cross-correlation function impact monitoring algorithms is compared. The results show that, in the monitoring area of 2 360 mm×1 260 mm, the error of the cross-correlation function algorithm is smaller than that of the time-reversal focusing algorithm, and the error of the time-reversal focusing algorithm is larger at the truss, which is not suitable for impact positioning of reinforced structures.

In order to select and cultivate germplasm resources of Leymus chinensis suitable for planting in Hinggan League area, four wild Leymus chinensis germplasm resources from different geographical distribution in Hinggan League were tested for phenological characteristics, morphological indexes, quantitative indexes and nutritional indexes, and correlation analysis and comprehensive evaluation were carried out. The results showed that both morphological and quantitative traits had different degrees of variation, ranging from 2.11%~43.10%. Among the nutritional indexes, the coefficient of variation of dry matter is the smallest, which is 0.26%. The coefficient of variation of crude protein is the highest, which is 20.94%. There was a significant positive correlation between plant height and leaf width (P<0.05) and extremely significant positive correlation with dry weight (P<0.01). The ranking of weighted correlation degree was YC01> YC02>YC04>YC03. The study indicates that YC01 germplasm has good production performance and comprehensive performance in Hinggan League. [ABSTRACT FROM AUTHOR]

The epidemic situation of coronavirus disease 2019(COVID-19) is developing rapidly in the world, and the influence is serious. In this study, the prescription of Mongolian medicine to prevent new type of COVID-19 was investigated. Based on the second edition and the third edition of COVID-19 Mongolian Medicine Prevention and Treatment Guidance Program issued by the Inner Mongolia Autonomous Region Health Commission, using Excel 2007, SPSS Modeler 18, SPSS Statistics 25, Cytoscape 3.7.1 statistical software as a tool, the association rules analysis and cluster analysis of Mongolian medicine included in the standard were carried out. Among the 45 prophylactic prescriptions included in the standard, a total of 34 high-frequency drugs using frequency ≥5 were used, of which Carthami Flos(21 times, 4.46%), Chebulae Fructus(20 times, 4.26%), Moschus(13 times, 2.77%), Myristicae Semen(12 times, 2.55%), Santali Albi Lignum(12 times, 2.55%), and Bovis Calculus(12 times, 2.55%) were the most common. The main drugs for the prevention of COVID-19 were Liang(13 times, 38.23%), Wen(9 times, 26.47%), the flavor was Ku(20 times, 34.48%), Xin(13 times, 22.41%), Gan(11 times, 18.97%), the most used drugs treating hot evil(99 times, 32.46%), treatment of &quot;Heyi&quot; drugs(51 times, 16.72%), treatment of &quot;Badagan&quot; drugs(40 times, 13.11%), treatment of &quot;sticky&quot; drugs(37 times, 12.13%), and a cough, eliminating phlegm and antiasthmatic(31 times, 10.16%), the association rule analysis found that the highest association intensity of the drug pair combination of 11. Clustering analysis using the cluster analysis of inter-group join method found a total of 8 categories. In this study, 45 prescriptions of Mongolian medicine for the prevention of COVID-19 were collec-ted and further analyzed, hoping to provide new ideas for clinical diagnosis and treatment.

Grassland is an important type of terrestrial ecosystem. Using remote sensing technology to study the change and driving force of native grassland productivity at large scale is an important way to understand the ecological status of grassland. In this study, potential and actual net primary productivity (NPP) of Xilingol steppe from 2000 to 2018 were examined based on climatic model and light-use efficiency model, respectively. NPP damage value driven by human activities was calculated from the difference between potential and actual NPP. The least square method was used to analyze the temporal and spatial variation of NPP in Xilingol and the driving role of climate and human activities on NPP. The results showed that NPP in Xilingol increased from west to east, with mean annual NPP being 271.54 g C·m -2 ·a -1 , the area with increased NPP (grassland restoration) being 36500 km 2 , and the area with decreased NPP (grassland degradation) being 59900 km 2 . The potential NPP tended to rise under the driving force of temperature and precipitation, with an average annual increase of 6.5 g C·m -2 ·a -1 , which indicated that regional climate played a positive role in the improvement of NPP in Xilingol steppe, and that human activities were the main driving force for grassland degradation. The value of NPP damage driven by human activities decreased from east to west and from south to north, with the highest value in Wuzhumuqin meadow and southern steppe. Human activities, such as mining and reclamation, had the most obvious negative impact on grassland NPP.

Objective: To explore the potential precursors of the anthraquinone metabolites from Rheum tanguticum and preliminanly identify the synthesis pathway thereof., Methods: Sterile seedlings sprouted from the seeds of Rheum tanguticum were chosen as materials for inducing callus. The effects of different precursors and feeding duration on the callus of Rheum tanguticum and the anthraquinone yield in adult rheum were studied., Results: The greatest improvement of anthraquinone yield was achieved by acetic acid, increasing 43. 9% for the callus and 45. 8% in the adult rheum; the second greatest improvement was achieved by malonic acid, increasing 15. 8% for the callus and only 3. 6% in the adult rheum. The yield of anthraquinone was not influenced significantly by benzoic acid and p-benzoquinone, and in contrast, was inhibited in some degree by shikimic acid and α-ketoglutaric acid. A suitable feeding duration was 36 h, which worked well for the effects of precursors., Conclusion: The precursor for synthesis of anthraquinone metabolites from Rheum tan- guticum is acetic acid, which improves the yields of callus and anthraquinone in adult rheum, concluding that the anthraquinone metabolites are synthesized via polyketone pathway.