Performing high-temperature measurements on the rotating parts of aero-engine systems requires wireless passive sensors. Surface acoustic wave (SAW) sensors can measure high temperatures wirelessly, making them ideal for extreme situations where wired sensors are not applicable. This study reports a new SAW temperature sensor based on a langasite (LGS) substrate that can perform measurements in environments with temperatures as high as 1300 °C. The Pt electrode and LGS substrate were protected by an AlN passivation layer deposited via a pulsed laser, thereby improving the crystallization quality of the Pt film, with the function and stability of the SAW device guaranteed at 1100 °C. The linear relationship between the resonant frequency and temperature is verified by various high-temperature radio-frequency (RF) tests. Changes in sample microstructure before and after high-temperature exposure are analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The analysis confirms that the proposed AlN/Pt/Cr thin-film electrode has great application potential in high-temperature SAW sensors.

The rotation of the helical micromachines can produce efficient motion efficiency at small-scale conditions and have the potential for multi-field applications. In this study, we propose self-scrolling schemes aiming at a flexible bilayer structure that includes the strained layer and magnetic layer. The magnetic layer is composed of magnetic nanocomposites and can respond to an external magnetic field. To cope with multistructural configurations, multipatterned manufacturing solutions of machines were investigated. Under the actuation of the rotating magnetic field, the swimming abilities of the helical machines are investigated in water and in a more viscous medium, exhibiting excellent movement abilities. For the purpose of transport capacities, the machines could be patterned with the containers, and their magnetic properties were studied to evaluate the effect of containers of different lengths on the movement performance; here, the direction of the magnetic axis and the stability of the rotational motion were investigated under different magnetization conditions. The result demonstrated that the larger radial deviation of the magnetic axis allows the machines to swim wobbly, and these instabilities can be reduced by radial magnetization.

Mercury (Hg) is a global pollutant that may potentially have serious impacts on human health and ecologies. The gaseous elemental mercury (GEM) exchanges between terrestrial surfaces and the atmosphere play important roles in the global Hg cycle. This study investigated GEM exchange fluxes over two land cover types (including Artemisia anethifolia coverage and removal and bare soil) using a dynamic flux chamber attached to the LumexR RA915+ Hg analyzer during the growing season from May to September of 2018, in which the interactive effects of plant coverage and meteorological conditions were highlighted. The daily mean ambient levels of GEM and the total mercury concentrations of the soil (TSM) were determined to be 12.4 ± 3.6 to 16.4 ± 5.6 ng·m−3 and 32.8 to 36.2 ng·g−1, respectively, for all the measurements from May to September. The GEM exchange fluxes (ng·m−2·h−1) during the five-month period for the three treatments included the net emissions from the soil to the atmosphere (mean 5.4 to 7.1; range of −27.0 to 47.3), which varied diurnally, with releases occurring during the daytime hours and depositions occurring during the nighttime hours. Significant differences were observed in the fluxes between the vegetation coverage and removal during the growing months (p < 0.05). In addition, it was determined that the Hg fluxes were positively correlated with the solar radiation and air/soil temperature levels and negatively correlated with the air relative humidity and soil moisture under all the conditions (p < 0.05). Overall, the results obtained in this study demonstrated that the grassland soil served as both a source and a sink for atmospheric Hg, depending on the season and meteorological factors. Furthermore, the plants played an important inhibiting role in the Hg exchanges between the soil and the atmosphere.

Dehui county is a typical agricultural area, with cultivated land accounting for more than 70% of the total land area. It has become a national agricultural demonstration area of "high yield, high quality and high efficiency". As a typical agricultural county in northeastern China and with the only title “China’s famous food city” in all the county-level cities, the environmental conditions of the soil in Dehui County with over 100 years city history face high ecological risks. In the present study, in order to more fully understand the characteristics of the soil mercury content and its related health risks in the main areas of Dehui County, the pollution degrees were evaluated using the data of land accumulation indexes (Igeo), potential ecological risk indexes (Er), and health risk assessment methods. The mercury content (TSM) levels in the soil, along with the atmospheric mercury content (TGM) levels, were analyzed. The results showed that the mean value of the mercury content in the soil in Dehui County was 0.0481 ± 0.0866 mg/kg, and the concentration range was between 0.0055 and 0.8155mg/kg. It was found that the mercury content levels in 34% of the soil samples exceeded the background value of soil (0.040 mg/kg). There was no significant correlation between atmospheric mercury concentration at 0 cm and soil mercury content. This may be due to the obvious migration of surface soil and fugitive dust due to the scouring of urban streets by runoff, which affects the distribution of mercury in surface soil. In addition, the low population density of small towns, the small number of large centralized coal-fired boilers, the low height of exhaust funnel and the absence of mercury removal measures for tail gas lead to the multi-source dry and wet deposition of atmospheric mercury on the surface. The mercury content levels in the soil were found to vary from different directions, with the mercury content found to be the highest in the central and eastern section of the county. However, there were no significant differences in mercury content of any direction. Igeo showed that 24.0% of the sample points were polluted. The insanitary areas were mainly concentrated in the central and western sections of the county. The mercury content levels in the soil of Dehui County ranged from pollution-free to mild pollution levels overall. The Er indicated that the potential ecological risk level was high in the central and eastern sections of Dehui County. However, the soil mercury levels in Dehui County presented a low level of ecological risk overall. The average values of the non-carcinogenic risks (HQ) and the total non-carcinogenic risk assessment indexes (HI) in all directions within Dehui County were determined to be far less than 1. Therefore, it was concluded that the soil mercury levels were not potentially harmful to human health.

Mercury (Hg) is a global and widely distributed heavy metal pollutant. Mercury can affect human health as well as the health of ecosystems and poses ecological risks. The subjects of this study are three types of grassland in the Beidianzi region, Songnen Plains, Northeastern China, characterized by different degrees of degradation. The mercury content levels in the atmosphere, soil, and forage grass on the different grasslands were determined. In addition, the relationships between the mercury pollution levels in the atmosphere and soil, and the mercury distribution correlations between the soil and plants, were examined in detail. The potential risk index (RI), single factor index (PI), and ground accumulation index (Igeo) were used to evaluate the ecological risks. The results showed that the mercury content in the soils of three types of grassland exceeded the China national standard (GB36600-2018), and the soil mercury content in the moderately degraded grassland was the highest. The single factor index method and land accumulation index method showed that the three types of grassland were slightly polluted, while the potential risk index showed that the three types of grassland were severely polluted, and the potential risk index of the moderately degraded grassland was the highest. The potential risk index decreased with the increase of soil depth. The variation trend of atmospheric mercury content was lower in the morning and evening and higher in the afternoon. The potential risk index of atmospheric mercury indicated that all types of grassland were at severe risk. There was a significant positive correlation between atmospheric mercury and soil mercury. The mercury content in herbage increased with the increase of degradation. The BP neural network prediction model constructed had good accuracy and had certain reference value.