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Grassland degradation levels determine plant eco‐physiological properties, and thus influences ecosystem function. However, how land degradation affects the relationship between plant biomass and eco‐physiological properties of native and artificially restored grasslands is insufficiently understood. Here, we evaluated aboveground biomass (AGB), plant photosynthetic capacity, as well as soil texture, in a series of native grasslands (non‐degraded, slightly degraded, moderately degraded, heavily degraded, and extremely degraded) and artificially restored grasslands with different growth times (5, 9, 11, 14 and 17 years) within the alpine grassland ecosystem of the Qinghai–Tibet Plateau during the plant growing season. Results showed that, in native grasslands, land degradation significantly decreased the nitrogen (N) concentration and AGB of grasses but did not impact the phosphorus (P) concentration. In actively restored grasslands, the AGB, photosynthetic rate (Pn), N and P of grasses decreased significantly after 9 years or longer of replanting time. Furthermore, the AGB of grasses in actively restored grasslands showed stronger association with eco‐physiological properties than in native grasslands. In native grasslands, degradation affected AGB directly, but also indirectly through Pn. In actively restored grasslands, degradation affected AGB directly, but also indirectly through Pn, N and P. Our findings suggest that the mechanisms by which grass species respond to degradation differ between native and actively restored grasslands. Also, compared to native grasslands, the eco‐physiological properties of grasses are more sensitive to changing environmental conditions in actively restored grasslands. More importantly, the differing response mechanisms are likely to alter the plant community dynamics and future ecosystem stability. [ABSTRACT FROM AUTHOR]

• Net ecosystem exchange (NEE) and its components are very sensitive to land degradation. • The alpine meadow ecosystems were a net carbon sink even though in ED grassland. • Land degradation eventually shifted Reco from autotrophic dominated to heterotrophic dominated. The effect of grassland degeneration on the emissions and sinks of carbon dioxide (CO 2) received extensive attention because of the increase of degraded area and the degeneration level in alpine meadow. To quantify its effect, we investigated net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (Reco), plant respiration (Rplant) and heterotrophic respiration (Rh), as well as environmental variability (soil water content (SWC), soil total carbon (STC), soil total nitrogen content (STN) and aboveground biomass (AGB)) from different degraded grasslands and non-degraded (ND) grassland in alpine meadow, Qinghai-Tibetan Plateau in growing season. The results indicated that compared with ND grassland, land degradation significantly decreased net CO 2 uptake (- NEE), GPP, Reco , Rplant and Rh by 60.61%, 63.22%, 67.53% 78.82% and 43.56%, respectively in extremely degraded (ED) grassland. These consistent responses suggested that the ecosystem CO 2 fluxes were very sensitive to grassland degradation. Degradation also decreased Rplant / Reco and Rplant / GPP by 16.8% and 8.1%, respectively, while increased Rh / Reco , Rh/Rplant and Rh/GPP by 16.8%, 41.4% and 3.8%, respectively, suggested that grassland degradation could eventually shifted Reco from autotrophic dominated to heterotrophic dominated. Four structural equation models (SEM) indicated that decline in NEE , GPP and Reco directly related to AGB and STC and decline in Rplant directly related to AGB , and indirectly related to SWC and STN. Our study highlighted that the consistent responses of CO 2 fluxes to grassland degradation could alter the ecosystem's carbon balance, and further would be influence carbon-climate feedbacks under deterioration of ecological environment. [ABSTRACT FROM AUTHOR]

Longwave infrared spectral imaging (LWIR-SI) has potential in many important civilian and military fields. However, conventional LWIR-SI systems based on traditional dispersion elements always suffer the problems of high cost, large volume and complicated system structure. Micro-electro-mechanical systems Fabry-Perot filtering chips (MEMS-FPFC) give a feasible way for realizing miniaturized, low cost and customizable LWIR-SI systems. The LWIR MEMS-FPFC ever reported can't meet the demands of the next-generation LWIR-SI systems, due to the limitation of small aperture size and nonlinear actuation. In this work, we propose a large-aperture, widely and linearly tunable electromagnetically actuated MEMS-FPFC for LWIR-SI. A multi-field coupling simulation model is built and the wafer-scale bulk-micromachining process is applied to realize the design and fabrication of the proposed MEMS-FPFC. Finally, with the rational structural design and fabrication process, the filtering chip after packaging has an aperture size of 10 mm, which is the largest aperture size of LWIR MEMS-FPFC ever reported. The fabricated electromagnetically actuated MEMS-FPFC can be tuned continuously across the entire LWIR range of 8.39-12.95 µm under ±100 mA driving current with a pretty good linear response of better than 98%. The developed electromagnetically actuated MEMS-FPFC can be directly used for constructing miniaturized LWIR-SI systems, aiming for such applications as military surveillance, gas sensing, and industry monitoring.

Fiber optic extrinsic Fabry-Perot interferometric (EFPI) sensors are ideal candidates for on-line partial discharges (PDs) monitoring due to their inherent advantages, such as immunity to electromagnetic interference (EMI), highly compact sensing probes, and remote signal transmission. However, up to date, the design and fabrication of high-performance sensing diaphragms still remain challenging, and most of the reported diaphragms utilize circular structures with the peripheral sidewalls completely fixed. Herein, a novel EFPI ultrasonic sensor for on-line PDs monitoring is demonstrated. The proposed sensing diaphragm combines a silicon beam-supported diaphragm and a fixed boundary ring with a thickness of 5 µm, which was optimized through the multi-objective genetic algorithm (MOGA) revealing its high design flexibility and manufactured by using the microelectromechanical systems (MEMS) processing technology on a silicon-on-insulator (SOI) wafer. Compared with the circular and beam-supported diaphragm, the developed structure exhibits a higher sensitivity. The testing results show that the developed sensor owns the sensitivity and noise-limited minimum detectable ultrasonic pressure (MDUP) of -10 dB re. 1V/Pa and 63 µPa/sqrt(Hz) at its designed resonant frequency, respectively. Finally, the sensor's ability to detect PDs is validated in a temporary built PDs experimental environment, further proving its great potential to perform the on-line PDs monitoring.