China has recently implemented a series of agricultural policy reforms to expand its agricultural sector and increase farm income. subsidies supporting agricultural sector growth are the favored policy even though they are known to exert a distorting effect on markets. Using a Policy Analysis matrix (PAm) model, we estimated the extent to which subsidies have distorted domestic markets and whether they have positively influenced China's comparative advantages in crop production and increased farm income. Results suggest that the effective protection of soybean and corn production has not significantly enhanced comparative advantage with respect to these commodities, while the effective protection of production factors used to produce wheat increased comparative advantage in wheat production.
The use of conductive polymer composites (CPCs) as strain sensors has been widely investigated. A wide range of strain sensitivities and high repeatability are vital for different applications of CPCs. In this study, the relations of the conductive filler network and the strain-sensing behavior and electrical stability under fatigue cycles were studied systematically for the first time based on the conductive polymethylvinylsiloxane (PMVS) composites filled with both carbon nanotubes arrays (CNTAs) and carbon black (CB). It was proved that the composites could be fabricated with large strain-sensing capability and a wide range of strain sensitivities by controlling the volume ratio of CNTA/CB and their amounts. Additionally, the CNTA/CB/PMVS composite with 3 vol % content of fillers showed high sensitivity (GF is 10 at 60% strain), high repeatability (the relative standard deviation (RSD) of the max R/R0 value is 3.58%), and electrical stability under fatigue cycles (value range of R/R0 is 1.62 to 1.82) at the same time due to the synergistic effects of the dual conductive network of CNTAs and CB. This could not be achieved by relying on a single CNTA or CB conductive network. This study may provide guidance for the preparation of high performance CPCs for applications in strain sensors.
Gas- and plasma-driven hydrogen permeation through GaInSn/Fe have been systematically investigated in this work. The permeation parameters of hydrogen through GaInSn/Fe, including diffusivity, Sieverts’ constant, permeability and surface recombination coefficient were obtained. The permeation flux of hydrogen through GaInSn/Fe shows a great dependence on external conditions such as temperature, hydrogen pressure, and thickness of liquid GaInSn. What’s more, the hydrogen permeation behavior through GaInSn/Fe is in good agreement with the multilayer permeation theory. In PDP and GDP experiments, hydrogen through GaInSn/Fe satisfies the diffusion-limited regime. In addition, the permeation flux of PDP is greater than that of GDP. The increase of hydrogen plasma density hardly causes the change of hydrogen PDP flux within the test scope of this work, which is due to the dissolution saturation. These findings provide guidance for a comprehensive and systematic understanding of hydrogen isotope recycling, permeation, and retention in plasma-facing components under actual conditions.
Atmospheric pressure plasma jet (APPJ) was used to clean nitrogen-containing carbon films (C-N) fabricated by plasma-assisted chemical vapor deposition (PACVD) method employing the plasma surface interaction linear device at Sichuan University (SCU-PSI). The properties of the contamination films on the surface of pristine and helium plasma pre-irradiated tungsten matrix, such as morphology, crystalline structure, element composition and chemical structure were characterized by scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS). The experimental results revealed that removal of C-N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates. Similar removal rates of 16.82 and 13.78 μm/min were obtained for C-N films deposited on smooth pristine tungsten surface and rough fuzz-covered tungsten surface respectively, which is remarkably improved in comparison to traditional cleaning method. However, slight surface oxidation was found after APPJ cleaning, but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm. Optical emission spectroscopy analysis and mass spectrometry analysis showed that C-N contamination was mainly removed through a chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas. These results make APPJ cleaning a potentially effective method for the rapid removal of C-N films from wall surfaces of fusion devices.
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