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In coal fire control, grouting/water extinguishing is often repeated for reasons such as re-ignition. The surrounding rock undergoes repeated heating and water cooling, resulting in strength reduction and damage, and collapse and cracks on the extended surface, resulting in potential safety hazards. Therefore, the change of rock mechanics under high temperature and cold cycle after peak is studied. Taking sandstone as the research object, the ultrasonic wave velocity and water absorption rate of rock samples were tested, and the uniaxial compression test was carried out. The mechanical damage characteristics of sandstone were analyzed, and its energy consumption evolution law was further explored. The results show that: from 500 ℃ after the peak, the attenuation rate of ultrasonic wave velocity and the change rate of water absorption of rock samples change from positive to negative, the wave velocity decreases and the water absorption increases; 500 ℃ is the threshold temperature of mechanical sudden change of high-temperature rock sample after the peak, and then the peak point of stress-strain curve moves rapidly to the right, the peak stress declines greatly, and the initial thermal damage caused by cold and hot cycles intensifies, and the ductile failure is obvious; the evolution characteristics of energy consumption are different in different stages of rock samples under pressure. From 500 ℃ after the peak, the proportion of dissipated strain energy before the peak is gradually larger than that of elastic strain energy, and the dissipated strain energy is negatively correlated with the mechanical strength.

BiFe1-xZnxO3 (BFZO) (x = 0, 2%, 4%, 6%) thin films were successfully prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. The effect of Zn doping on the structure, surface morphology, leakage current density, ferroelectric and ferromagnetic properties of BiFeO3 (BFO) thin films were investigated systematically. XRD patterns show that all samples match well with the perovskite structure without impurity phase. SEM images show that BFZO thin films with x = 4% exhibit uniform fine grains and higher density, which is instrumental for the improvement of leakage current density. The leakage current density curve shows that BiFe0.96Zn0.04O3 thin films have the lowest leakage current density (J = 1. 56 x 10-6 A/cm²) under the electric field strength of 300 kV/ cm, which is three orders of magnitude lower than that of pure BFO thin films. Furthermore, BiFe0.96Zn0.04O3 thin film exhibits the largest remnant polarization (2Pr = 20. 91 μC/cm²) at room temperature, which is more than four times as large as that of pure BFO (2Pr = 4. 96 μC/cm²). Additionally, compared with BFO thin film, Zn doping also enhances the ferromagnetic properties of BFO thin films, and as Zn doping concentration increases, the saturation magnetization of BFZO thin films is significantly enhanced, which provides potential applications in information storage. [ABSTRACT FROM AUTHOR]

Use of fish as biological early warning indicator for ecological hazards of water pollutants is efficient and fast. However, there is still a lack of attempts to apply fish shoaling behavior to biological early warning. Herein, cluster score was used to evaluate and quantify shoaling behavior of rare minnow ( Gobiocypris rarus) in their health state. Combined with the results of 24 h acute toxicity exposure experiment, the response of rare minnow shoaling behavior to Cd2+, MS222 and p-chloroaniline was tested by gradient exposure experiment and burst pollu- tion simulation experiment. The results showed that rare minnow had obvious shoaling behavior with a cluster score between 3 and 5, which changed significantly when exposed to chemicals. The LOEC values of shoaling behavior of rare minnow exposed to Cd2+, MS222 and p-chloroaniline for 1 h were 3, 11 and 10 mg·L-1, respective- ly. The shoaling behavior of rare minnow was sensitive to the chemical reaction and showed obvious response within 10 min after exposure to the three chemicals. Therefore, cluster score is an excellent quantitative parameter of fish shoaling score, and the shoaling behavior of rare minnow is a great indicator of biological early warning. [ABSTRACT FROM AUTHOR]

In order to clarify the main meteorological risk factors and their spatial and temporal distributions for flue-cured tobacco growing in Guizhou Province, daily average temperature, maximum temperature and rainfall data of 64 counties (districts or cities) in Guizhou Province from 2008 to 2017 were gathered. The main meteorological risk factors of flue-cured tobacco at different growth stages in different counties and districts were evaluated using cluster analysis method to classify the meteorological risk factors. The results showed that the main meteorological risks were low temperature from the shoot restoring stage to the root extending stage (average daily temperature ≤13 c from late-April to mid-May), high temperature at the mature stage (the highest daily temperature ≥35 c from mid-July to late-August), low temperature at the late mature stage (average daily temperature ≤20 C from early-August to early-September) and heavy rain (daily rainfall ≥50 mm). The risk of low temperature from the shoot restoring to the root extending stage as well as the late mature stage mainly occurred in western Guizhou, including Weining and Dafang in Bijie, Shuicheng in Liupanshui, and Pu'an in Qianxinan. Among them, Weining in Bijie had the highest risk of low temperature whose average number of low temperature days in the early period (from late April to mid-May) was 12 days and was as high as 40 days in the latter period (from early August to early September). The risk of high temperature at the mature stage mainly occurred in Tongren and Qiandongnan. Among them, the risk of high temperature for Yanhe in Tongren was the highest. Within the growth stages of flue-cured tobacco, the rainfall was abundant, but the inter-annual differences were large. The rainfall in the southwest and the eastern regions was significantly higher than that in the central region. The central region only experienced drought in a few years with the longest consecutive rain-free period of 10-15 days. Heavy rains occurred in Anshun and its surrounding counties. The annual average number of rainstorm days was about 4 days, and the average annual rainstorm rainfall was greater than 300 mm. Songtao in Tongren faced dual risks of heavy rain and high temperature at the mature stage. [ABSTRACT FROM AUTHOR]

In order to optimize tobacco flue-curing processing parameters, the temperature and humidity data during flue-curing were collected from 3 tobacco planting areas in Henan by using the technology of IoTs (internet of things) . The durations and indexes of temperature and humidity of the curing process were analyzed and compared with flue-curing technologies at home and abroad. The results showed that: 1) The total curing time of middle and upper tobacco leaves was mainly in ranges of 6.5-8.0 days and 7.0-8.5 days respectively, and the fluctuation of wet bulb temperature was relatively drastic during the flue-curing process of upper leaves. 2) The proportions of yellowing, color-fixing and stem-drying durations to total flue-curing time were about 40%, 35% and 25% respectively in south and west Henan, while the yellowing duration in middle Henan was longer, accounting for 55% of the total flue-curing time. 3) The temperatures during yellowing, color-fixing and stem-drying stages were mainly in ranges of 40-42 °C, 43-48 °C and above 61 °C respectively. The wet bulb temperature from the late yellowing stage to stem-drying stage of each area was 1-2 °C lower than the three-phase curing technology. 4) Correlation analysis indicated that the regulation of wet bulb temperature from yellowing stage to middle color-fixing stage was closely related with the curing process. Considering the flue-curing technology at home and abroad, the durations of yellowing stage at 38 °C and color fixing stage at 54 °C could be appropriately prolonged, and the wet bulb temperature from late yellowing stage to color-fixing stage should be reasonably regulated to avoid drastic fluctuation, so as to promote the rational transformation of chemical components in tobacco leaves during flue-curing process. [ABSTRACT FROM AUTHOR]

Objective: To review the effects and mechanisms of various myokines secreted by skeletal muscle on various bone tissue cells., Methods: Literature related to myokines and their regulation of bone tissue cells was reviewed and analyzed comprehensively in recent years., Results: Bone and skeletal muscle are important members of the motor system, and they are closely related in anatomy, genetics, and physiopathology. In recent years, it has been found that skeletal muscle can secrete a variety of myokines to regulate bone marrow mesenchymal stem cells, osteoblasts, osteoclasts, and bone cells; these factors mutual crosstalk between myoskeletal unit, contact each other and influence each other, forming a complex myoskeletal micro-environment, and to some extent, it has a positive impact on bone repair and reconstruction., Conclusion: Myokines are potential targets for the dynamic balance of bone tissue cells. In-depth study of its mechanism is helpful to the prevention and treatment of myoskeletal diseases.