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ABSTRACT Purpose: To explore the role and mechanism of curcumin (Cur) in reducing oxidative stress damage in rats with nephrolithiasis induced by ethylene glycol (EG). Methods: Thirty male rats were divided into normal control, model, positive (10% potassium citrate), Cur-10 (10 mg/kg curcumin) and Cur-20 (20 mg/kg curcumin) groups. Results: The results of kidney tissue section stained by hematoxylin-eosin and von Kossa showed that curcumin treatment can inhibit the formation of kidney stones. The biochemical test results showed that the urea (Ur), creatinine (Cr), uric acid (UA), inorganic phosphorus and Ca2+ concentrations in urine decreased after being treated with curcumin. There were significant differences between different doses of curcumin (P < 0.05). Compared with the Cur-10 group, Cur-20 had a more significant inhibitory effect on malondialdehyde (MDA) (P < 0.05). In addition, reverse transcription polymerase chain reaction (PCR) detection and immunohistochemical results indicated that the osteopontin (OPN) in the kidney was significantly reduced after curcumin treatment. Conclusions: Curcumin could reduce the oxidative stress damage caused by EG-induced kidney stones.

The conflict between ecological protection and socio-economic development in the old revolutionary base areas along the route of Long March can be addressed by ecological compensation. In this study, we collected 2018 data of land use, net primary productivity of vegetation, climate factors and so on. The ecosystem service value of 310 counties in the old revolutionary base areas was calculated using the data and modified equivalent factor. Then, the regional differentiated ecological compensation estimation method was applied to estimate the priority and amount of ecological compensation within the area. We further proposed the ecological compensation strategy adopted for the old revolutionary base areas along the route of Long March. The results showed that the total value of ecosystem services in the old revolutionary base areas along the route of Long March amounted to 2593.74 billion yuan in 2018. Forest services took the highest proportion (58.8%), followed by grassland and waters. The total amount of ecological compensation made for the old revolutionary base areas along the route of Long March reached 183.405 billion yuan. Compared with this amount, there was a large gap in the actual compensation funds available to the region. In addition, the total amount of ecological compensation accounted for only 0.04% of the aggregate GDP in this area, which put some strain on local fiscal resources and showed certain viability in ecological compensation. In 2018, totally 100 old revolutionary base areas along the route of Long March were designated as the priority areas for ecological compensation, consistent with the national key eco-function zone policy. However, there were deviations in the allocation of ecological compensation funds, with some priority areas receiving no compensation. As for the compensation strategy, it is necessary to put in place a diversified, market-oriented and comprehensive ecological compensation mechanism to increase the sources of ecological compensation funds at first. Then, efforts should be continued to optimize the spatial selection of ecological compensation in the old revolutionary base areas along the route of Long March and to improve the efficiency of regional ecological compensation mechanism.

Exploring the spatial-temporal variations of agricultural eco-efficiency (AEE) and its driving factors is of vital importance to achieve high-quality agro-ecological development in China. In this study, we used the super efficiency slack-based measure (SBM) model to measure the inter-provincial AEE based on the relevant panel data of 30 provinces/regions/cities in China from 2000 to 2018. Based on the time series analysis, spatial visualization, and trend surface analysis, the geographical detector model was further used to identify the core factors driving the spatial-temporal variations of AEE. The results showed that China's AEE level maintained stable upward progress from 2000 to 2018, which was still at a low level with much room for improvement. The AEE in China exhibited a significant spatial-temporal variation, presenting higher levels in the eastern and western parts but lower in the central part. The spatial variation of AEE was influenced by many factors, including agricultural resource endowment, socioeconomic condition, and the natural ecological environment. There were obvious variations in the influence factors on the spatial-temporal variation of AEE. The interactions among factors would enhance the spatial variation of AEE. Therefore, due to the spatial-temporal variation of AEE, emphasis should be placed on its core driving factors as well as the inter-parts agricultural cooperation in order to achieve high-quality agro-ecological development in China.

Based on the panel data of 255 cities in China, this study built a spatial Durbin model to study the impact of China's industrialization on the PM 2.5 pollution level. Meanwhile, an environmental governance tool characterized by forest and grass coverage was introduced to explore the internal mechanism and exogenous driving force of EKC. The results show that ① the relationship between industrialization and PM 2.5 concentration is obviously an inverted u-shaped, and the EKC hypothesis was verified. ② The formation of the EKC curve was caused by the external factors and not the endogenous mechanism of economic growth. Forest-grass coverage plays a regulating role in the relationship between industrialization and PM 2.5 pollution level, namely the inverted u-shaped structure of environmental EKC results from environmental governance tool with forest and grass cover rather than the automatic adjustment of economic growth. ③ The influence of industrialization on PM 2.5 concentration has a spatial spillover effect. Urban industrialization not only affects the PM 2.5 concentration in local regions but also its neighboring region.