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The Dengfeng coalfield belongs to the typical "three soft" coal seam and has a high gas content ranging from 10 to 13 m3/t, and the coal seam gas content reaches a maximum 13.69 m3/t. Because of its coal seam occurrence, no protective layer can be mined. The conventional regional pre-pumping measures have several problems. For example, the construction of a pre-pumping borehole is difficult, and it easily causes a coal and gas outburst. The low permeability and rheological characteristics of the coal seam lead to the collapse of the borehole and seriously affects the drainage effect. The influence radius of the drainage borehole is small, which results in a larger quantity of new drilling boreholes and significantly increases the operational cost. Compared to the conventional regional pre-pumping measures, floor roadway hydraulic flushing rapid outburst technology can effectively overcomes these issues. Hydraulic flushing uses water to flush the borehole, and the newly formed fractures and the release of free gas greatly reduce the elastic potential and gas expansion energy of coal and rock, which thus significantly improve the permeability of the coal and improve the coal seam degasification efficiency for outburst risk control. In this paper, a hydraulic punching method is utilized for coal seam stimulation in the Machi mine. Reasonable technical parameters of hydraulic punching were obtained: the water pressure of punching and breaking coal is 8–15 MPa, and the equivalent diameter of the hydraulic punching nozzle should be < 7.47 mm. After the implementation of the hydraulic punching measures, the gas extraction capacity of the coal around the borehole is greatly improved. For 90 days gas extraction after stimulation, the gas content of the 11,061 lane decreased from 8.42–12.12 m3/t to 3.09–5.75 m3/t, relieving pressure and increasing permeability of "three soft" coal and simultaneously eliminating the outburst danger of the coal seam. [ABSTRACT FROM AUTHOR]

Unmanned surface vehicles (USVs) are playing a significant role in the marine science and engineering field, e.g., they have been widely used in measuring ocean waves and currents. However, their operation time and range are limited by the energy carried by internal batteries, and this challenge needs to be urgently addressed. In this study, a novel USV concept that can harvest vibration energy excited by ocean waves in the heaving and pitching direction is presented, which provides a sustainable and continuous power supply. A fully coupled wave-to-wire model that considers the viscous damping force is developed to investigate the dynamics and electric power performance of this novel device under site-specific realistic wave climates, with the external electric load optimally tuned for each sea state. Besides, the influence of the forward speed, geometric size, mass ratio and end-stop spring is studied. Numerical results show that the proposed USV in a freely floating situation can efficiently capture and convert harvested energy into electricity with a wave-to-wire efficiency of up to 20. 21 %. Additionally, it can generate an annual mean electric power of 29.73 W, under the wave climates of the national wave energy test site in China. • A novel wave-powered unmanned surface vehicle is designed. • A fully coupled wave-to-wire model is developed. • A high wave-to-wire efficiency up to 20.21% is obtained. • An annual mean electric power of 29.73 W is achieved by the USV. [ABSTRACT FROM AUTHOR]

Improving capacity utilization (CU) is a critical way for China to promote economic transformation and achieve sustainable development. As a market-based environmental regulation proposed to achieve a low-carbon economy and green transformation, whether emission trading system (ETS) can improve CU deserves an in-depth study. We conduct an empirical study by constructing a multi-period difference-in-differences model with 1,037 Chinese A-share listed firms from 2004 to 2020 as the research sample. The result shows that the ETS can significantly improve CU, which still holds after a series of robustness tests. The mechanism analysis shows that the ETS improves CU through three mechanisms: stimulating green innovation, restricting over-investment, and alleviating financing constraints. Based on the heterogeneity analysis, the improvement of CU by ETS is greater among listed firms in heavy-polluting industries, with good ESG performance, excess leverage, and central state ownership. Our study supports the global implementation of the ETS and provides ideas for resolving overcapacity in the context of global decarbonization. [ABSTRACT FROM AUTHOR]

Abstract: GPR (Ground penetrating radar) is one kind of the detection technologies with rapid, non-destruction, uninterrupted detection, and high-resolution. GPR can be applied to detect underground holes and loose soil layer and the other baneful anomalies, and therefore is widely applied to hole survey of the subway project in recent years. Based on briefly describing engineering geological background between F station and L station of a subway project in Beijing, this paper gives the arrangement method of GPR survey line in the construction area of shield method, analyzes detection results, verifies an anomaly by spading, determines the distribution range and its characteristic of the hole anomalies. The results showed that three obvious anomalies were detected in the area between F station and L station, and seriously loose soil layer was the cause of No. 1 and No. 3 anomalies, and hole was the cause of No. 2 anomaly. Thereby the anomalies of loose soil layer and hole could be detected accurately by the GPR technology, and then basic data of underground holes could be obtained. On the base of analyzing these data, effective measures could be adopted to avoid the hidden danger, then the safety of subway construction and surrounding environment of the subway project could be ensured. [Copyright &y& Elsevier]

A ca. 4000a decadal-resolution climate proxy record of the mean grain-size from a lake (or mash) sediment at the southern margin of the Tarim Basin, correlates visually with the atmospheric 14C record from tree ring (residual Δ14C, solar proxy) and the GISP2 ice core δ18O record (temperature proxy). In general, Δ14C maxima (solar minima) are coincident with cold (wet) periods in the study area and cold periods in the Greenland ice core. Power spectrum analysis revealed statistically significant periodicities of 196a, 121a, 97a, 62a, 45a and 33-30a, which are similar to those principal solar-oscillation periods as inferred from the atmospheric radiocarbon and other proxy records. Possible solar forcing is addressed to be the main driving forcing of climate change in the southern margin of Tarim Basin. [ABSTRACT FROM AUTHOR]

In global climate change, improving carbon productivity holds great importance for China's sustainable growth. Based on panel data of 30 Chinese provinces and cities from 1997-2017, the drivers, spatial effects, and convergence characteristics of carbon productivity in China are explored by combining a factor decomposition framework and a spatial panel model. The findings show that (1) China's carbon productivity shows continuous positive growth, and the substitution effect of capital for energy dominates this changing pattern; (2) There is a β-convergence trend and club convergence in China's carbon productivity, and the spatial technology spillover accelerates the convergence rate; (3) With its accelerated industrial transformation and technological upgrading, China's current carbon productivity converges faster than its earlier stage, and the role of physical capital investment has gradually shifted to suppression. In contrast, the positive push of human capital investment has been strengthened; (4) From the perspective of the realization mechanism, the convergence of carbon productivity in China mainly comes from the convergence of energy restructuring and capital-energy substitution. These findings can help China narrow the inter-provincial carbon productivity gap in terms of improving factor structure, upgrading technology, etc., and provide references for sustainable growth decision making in China and around the world.

Information on placental transfer and adverse outcomes of short-chain per- and polyfluoroalkyl substance (PFASs) is limited, and factors responsible for PFAS placental transfer are still unclear. In the present study, concentrations of 21 PFASs were analyzed in 132 paired maternal and cord serum samples collected from residents in Beijing, China, and the placental transfer efficiency (PTE) of each PFAS was calculated. PTEs of short-chain perfluoroalkyl acids (PFAAs), including PFBA (146%), PFBS (97%), PFPeA (118%), and PFHxA (110%), were first reported, and a complete U-shaped trend of PTEs from C4 to C13 of perfluoroalkyl carboxylic acids (PFCAs) was obtained. Positive association between maternal weight and PTE of perfluorooctanesulfonate (PFOS) ( p < 0.05) and negative association between maternal PFBA concentration and birth length ( p < 0.01) were observed. Using in vitro experiments, we further determined equilibrium dissociation constants ( K d s) of human serum albumin (HSA)-PFAS complexes ( K d-HP ), serum proteins-PFAS complexes ( K d-SP ), and liver-fatty acid binding protein (L-FABP)-PFAS complexes ( K d-LP ) and found that they were all significantly correlated with PTEs of PFASs. The correlation coefficient was 0.92, 0.89, and 0.86, respectively ( p < 0.01 in all three tests), suggesting that K d s of protein (serum)-PFAS complexes can play an important role in trans-placental transfer of PFASs in human and K d-HP plays a pivotal role.

The vertical and horizontal distribution of nonylphenol polyethoxylates (NPEO(n), n = number of ethoxy units) and their derivatives in the Upper Nansi Lake, North China, were investigated using high-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. For the water-phase concentrations of these compounds, data are omitted because of their low concentration levels. The content of NPEO(n) (n = 1 to 15) bound onto the sediment of this lake changed in the range of 60.7 to 631.5 microg/kg dry for sediment cores with a thickness up to 350 mm. A typical increasing trend of the nonylphenol (NP) content was revealed along the water flow direction of this lake. Carbonated NPEO(n) (NPE(n)C) showed an increasing trend from upstream to downstream, with the total concentrations of the NPEO(n) falling in the range of 2.13 to 23.1 microg/kg dry. Results indicate that this lake received some effluent from wastewater treatment plants, whose treatment ratios are relatively low in this area. The nonoxidative hydrolytic transformation is a significant process occurring within the sediment phase of Nansi Lake.