Exogenous spermidine improved drought tolerance in Ilex verticillata seedlings

Winterberry (Ilex verticillata (L.) A. Gray) is a recently introduced ornamental tree species in China that has not been closely investigated for its drought resistance. In this study, we used two-year-old cuttings from I. verticillata (L.) A. Gray and two representative varieties derived from it, I. verticillata ‘Oosterwijk’ and I. verticillata ‘Jim Dandy’, as materials to investigate how this plant responds to drought stress and whether exogenous spermidine (SPD) can alleviate the negative effects caused by drought stress. The results showed that as the degree of drought stress increased, the leaves of winterberry seedlings became chlorotic, and their edges became dry. Similarly, the relative water content, specific leaf weight, chlorophyll content, leaf nitrogen content, net photosynthetic rate, stomatal conductance and transpiration rate were significantly reduced, whereas the content of malondialdehyde continuously increased with the degree of drought stress. The activities of superoxide dismutase, peroxidase, and catalase increased under moderate drought stress and then decreased under severe drought stress. The levels of soluble sugar and abscisic acid continued to increase, while those of auxin and gibberellic acid decreased. When compared with individual drought stress, an increase in the amount of external SPD clearly alleviated the effect of drought stress on winterberry seedlings. The combined phenotypes and physiological indices of the winterberry leaves under drought stress conditions revealed that the drought resistance of the native species was significantly higher than its two varieties. This finding serves as an important theoretical foundation for the popularization and application of I. verticillata (L.) A. Gray and the two varieties

Research on Periodic Motion Stability of Rotor-Bearing System with Dual-Unbalances

Abstract. Multiple freedom degrees model of rotor-bearing system taking many factors into account is established, the Newmark-β and shooting method are combined during the stability analysis of periodic motion in such system. The paper focused on the influence law of two eccentric phase difference on the instability speed of rotor-bearing system. The results have shown that the instability speed rises constantly with the eccentric phase difference angle increasing in small eccentricity system. When the two unbalance be in opposite direction, the system reached its maximum instability speed. However, the unstable bifurcation generates mutation phenomenon for large eccentricity system with the eccentric phase difference angle increasing. In summary, the larger initial phase angle can inhibit system instability partly. The conclusions have provided a theoretical reference for vibration control and stability design of the more complex rotor-bearing system

Bone Morphogenetic Protein-7 (BMP-7) Promotes Neuronal Differentiation of Bone Marrow Mesenchymal Stem Cells (BMSCs) In Vitro

This study is aimed at investigating the effects of bone morphogenetic protein-7 (BMP-7) on the differentiation of bone marrow mesenchymal stem cells (BMSCs) into neuron-like cells in vitro. The rat BMSCs were isolated and identified, which were divided into the control, empty, recombinant rhBMP-7 transfection, and Lv-BMP-7 transfection groups. BMSCs were induced under different conditions. CCK-8 assay was performed to detect cell proliferation. ALP was used to detect cell activity. Cellular morphology after induction was observed. Immunofluorescence was conducted to detect the expression and location of nerve cell markers. Quantitative real-time PCR and Western blot analysis were performed to detect the mRNA and protein expression levels, respectively. The rhBMP-7 and Lv-BMP-7 promoted the proliferation of BMSCs, accompanied with increased ALP activities. Morphological observations revealed that rhBMP-7 and Lv-BMP-7 induced BMSCs to differentiate into neuron-like cells. Immunofluorescence revealed that the rhBMP-7 and Lv-BMP-7 groups showed positive expression of MAP-2 and Nfh in BMSCs. MAP-2 was mainly distributed in the cell body and cellular protrusion, while Nfh was mainly distributed in the cytoplasm and cell protrusion. Positive mRNA and protein expressions of MAP-2 and Nfh were observed in the cells of the rhBMP-7 and Lv-BMP-7 groups, and the expression levels were significantly higher than the control and empty groups. Both exogenous BMP-7 (rhBMP-7) and endogenous BMP-7 (Lv-BMP-7) can induce BMSCs to differentiate into neuron-like cells highly expressing the neuronal markers MAP-2 and Nfh

Spatio-temporal development characteristics of major geohazards in Sichuan Province around "5·12" Wenchuan earthquake

The temporal and spatial development law of regional geohazards is the result of the joint action of internal and external geological forces, which are relatively stable within a large area. Therefore, the source, magnitude and occurrence time of earthquakes are the main factors affecting the temporal and spatial development law of regional geohazards. In order to study the impact of "5·12" Wenchuan earthquake on the spatial and temporal development of geohazards in Sichuan Province, based on the data of landslide, collapse, debris flow, earthquake and rainfall from 1998 to 2018, the spatial and temporal characteristics of major geohazards in Sichuan Province around the Wenchuan earthquake were analyzed by mathematical statistics and spatial analysis methods, The results show that: ① Activity in major disasters in Sichuan Province shows cycles, under normal circumstances, it presents a small cycle of about 3 years, after the earthquake geohazards increased year by year, to the peak of 4a, then decreased year by year; the impact is not obvious after 8 years; ② The relative intensity of major geohazards has little change after the earthquake, but the activity and intensity of geohazards are not corresponding before the earthquake. In the geomorphic division, the largest number of geohazards is in Sichuan Basin, and the most active is in Northwest Sichuan Plateau. Compared with that before the earthquake, the occurrence of geohazards in the quaternary system is higher than that in the hard rock area. The geohazards in the tectonic zones have obvious zoning characteristics. The earthquake intensity of the Yangtze quasi-platform is much greater than that of the Songpan-Ganzi geosynclinal fold system before and after the earthquake, but the disaster activity is obviously weaker than that of the Songpan-Ganzi geosynclinal fold system, and the basic structural units have similar characteristics

Potential Sources, Pollution, and Ecological Risk Assessment of Potentially Toxic Elements in Surface Soils on the North-Eastern Margin of the Tibetan Plateau

Due to increased levels of human activity, various pollutants are frequently detected on the Tibetan Plateau, where the environment is extremely fragile and sensitive. Therefore, this study investigated the sources, pollution, and ecological risks of soil potentially toxic elements (PTEs) in different landscape areas within the Qaidam Basin in the northeastern part of the Qinghai–Tibet Plateau. The contents of seven PTEs (Cd, Cu, Pb, Zn, As, Cr, and Ni) in 32 topsoil samples (0–2 cm) were analyzed in different regions of the Qaidam Basin. The concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn were 10.4–29.9 mg/kg, 0.08–4.45 mg/kg, 19–66 mg/kg, 8.2–40 mg/kg, 11.7–30.8 mg/kg, 11.1–31.2 mg/kg, and 32–213 mg/kg, respectively. The correlation between Pb and Cd in unpopulated areas was 0.896 (p < 0.01). The correlations among Pb, Cd, and Zn in agricultural areas, among As, Cd, Cr, and Zn in saline lake areas, and among As, Cd, Cr, Cu, Ni, Pb, and Zn in residential areas were all greater than 0.65 (p < 0.05). The principal component analysis results showed that Pb and Cd in unpopulated areas, Pb, Cd, and Zn in agricultural areas, As, Cd, Cr, Zn, and Pb in saline lake areas, and As, Cd, Cr, Cu, Ni, Pb, and Zn in residential areas were affected by human activities (significant factor >0.70). Based on the geological accumulation index and single-factor pollution index results, the maximum Cd values were found to be 4.93 and 45.88, respectively; Cd was thus the most serious PTE pollutant. The comprehensive pollution index of Nemero showed that moderately and severely polluted areas accounted for 18.89% and 18.46% of the total area, respectively. The results of the potential risk index showed that very strong and strong ecological risk points together accounted for 18.8% of the total points. The spatial variations in PTE pollution and the potential ecological risk index had similar patterns; both increased from the unpopulated areas in the northeastern Qaidam Basin to Golmud city in the south-western Qaidam Basin. These results indicate that human activities negatively impacted the soil ecological environment in the Qaidam Basin during the rapid development of the economy and urbanization and that these negative impacts tended to spread to unpopulated areas. Therefore, it is necessary to emphasize the significant impacts of human activities on environmental quality and formulate preventive measures to reduce PTE pollution in the Qinghai–Tibet Plateau

Construction of case base system of mine water disaster under background of big data

In order to improve informationization level of coal mine water disaster prevention, and realize changes of mine water disaster prevention work from qualitative to quantitative and from experience to science, purpose and principles of construction of case base system of coal mine water disaster prevention and control under background of big data were proposed, and structure and function modules were designed. Key technologies of IoT, cloud computing, big data were analyzed. The case base system of coal mine water disaster integrates accident management, water disaster prevention, safety education and technical training

Soil ecological risk assessment of ten industrial areas in China based on the TRIAD and VIKOR methods

The TRIAD approach is widely used as a scientific methodology available to deal with site-specific contamination scenarios. In this study, a soil environmental risk assessments (SERA) of ten industrial sites in China was conducted by ranking risks across multiple sites based on the TRIAD method, and attempted to provide an alternative method for risk ranking, the VIKOR method, when reference screening values for assessing individual indicators are unavailable. The VIKOR method was developed to address ranking and selection problems in multi-criteria decision-making, particularly in complex decision environments. The present assessments analyzed 33 chemical analysis indicators, 14 ecotoxicological indicators, and 5 ecological indicators related to soil microbial diversity, subsequently compared and discuss the differences in risk ranking results obtained using the two methods. The results of the TRIAD approach showed that six sites (including F, G, E, B, J and I) were ranked high in the risk order, which were in the moderate-risk range (Integrated risk value, 0.5–0.75). While the results of the VIKOR method showed that four sites (including F, G, H, and E) were ranked high in the risk order, followed by another four sites (including D, A, B, and C). Although there were differences in the assessment results, both methods consistently identified three sites (including F, G, and E) with relatively higher risks. The results indicated that when the TRIAD method is not applicable in special cases, the VIKOR comprehensive evaluation can be used to infer the relative ecological risk of the assessed site

Precision Grinding Technology of Silicon Carbide (SiC) Ceramics by Longitudinal Torsional Ultrasonic Vibrations

Silicon carbide (SiC) ceramic material has become the most promising third-generation semiconductor material for its excellent mechanical properties at room temperature and high temperature. However, SiC ceramic machining has serious tool wear, low machining efficiency, poor machining quality and other disadvantages due to its high hardness and high wear resistance, which limits the promotion and application of such materials. In this paper, comparison experiments of longitudinal torsional ultrasonic vibration grinding (LTUVG) and common grinding (CG) of SiC ceramics were conducted, and the longitudinal torsional ultrasonic vibration grinding SiC ceramics cutting force model was developed. In addition, the effects of ultrasonic machining parameters on cutting forces, machining quality and subsurface cracking were investigated, and the main factors and optimal parameters affecting the cutting force improvement rate were obtained by orthogonal tests. The results showed that the maximum improvement of cutting force, surface roughness and subsurface crack fracture depth by longitudinal torsional ultrasonic vibrations were 82.59%, 22.78% and 30.75%, respectively. A longitudinal torsional ultrasonic vibrations cutting force prediction model containing the parameters of tool, material properties and ultrasound was established by the removal characteristics of SiC ceramic material, ultrasonic grinding principle and brittle fracture theory. And the predicted results were in good agreement with the experimental results, and the maximum error was less than 15%. The optimum process parameters for cutting force reduction were a spindle speed of 22,000 rpm, a feed rate of 600 mm/min and a depth of cut of 0.011 mm