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The salt corrosion environment has direct degradation to durability of asphalt mixture and dynamic water also has an important influence on asphalt pavement performance. In order to evaluate the performance of asphalt mixture exposed to dynamic water and chlorine salt erosion, the asphalt mixture dynamic water-salt erosion apparatus was self-designed and the test parameters were reasonably set for the accelerated simulation of chlorine salt-water-temperature-load coupling action to asphalt mixture under real working conditions. Splitting test (25 °C and −10 °C) was adopted for assessing the performance of asphalt mixture suffered from chlorine salt-water-temperature-load coupling action. Then the grey entropy method was applied to analyze the significance of influencing factors on the performance of asphalt mixture such as dynamic water scouring times, temperature, salt solution concentration. Then the mechanism of performance deterioration of asphalt mixture was explored to some extent. The results show that the process of chlorine salt erosion and deterioration to asphalt mixture is accelerated by dynamic water and is closely related to the concentration and temperature of salt solution. Scouring times is the most significant factor influencing the performance of asphalt mixture exposed to dynamic water and chlorine salt erosion. The crystallization erosion caused by salt solution infiltrating into the voids and cracks of asphalt mixture is an important inducement for the performance deterioration.

Bismuth (Bi) has been known as a highly efficient electrocatalyst for CO2 reduction reaction. Stable free-standing two-dimensional Bi monolayer (Bismuthene) structures have been predicted theoretically, but never realized experimentally. Here, we show the first simple large-scale synthesis of free-standing Bismuthene, to our knowledge, and demonstrate its high electrocatalytic efficiency for formate (HCOO−) formation from CO2 reduction reaction. The catalytic performance is evident by the high Faradaic efficiency (99% at −580 mV vs. Reversible Hydrogen Electrode (RHE)), small onset overpotential (, Stable free-standing two-dimensional Bi monolayer (Bismuthene) structures have been predicted theoretically, but never realized experimentally. Here, the authors show a large-scale synthesis of free-standing Bismuthene and its electrocatalytic activity for CO2 reduction to formate.

The electrochemical reduction reaction of carbon dioxide (CO2RR) to carbon monoxide (CO) is the basis for the further synthesis of more complex carbon-based fuels or attractive feedstock. Single-atom catalysts have unique electronic and geometric structures with respect to their bulk counterparts, thus exhibiting unexpected catalytic activities. A nitrogen-anchored Zn single-atom catalyst is presented for CO formation from CO2RR with high catalytic activity (onset overpotential down to 24 mV), high selectivity (Faradaic efficiency for CO (FECO ) up to 95 % at -0.43 V), remarkable durability (>75 h without decay of FECO ), and large turnover frequency (TOF, up to 9969 h-1 ). Further experimental and DFT results indicate that the four-nitrogen-anchored Zn single atom (Zn-N4 ) is the main active site for CO2RR with low free energy barrier for the formation of *COOH as the rate-limiting step.

Sulfate erosion is a threat to durability and sustainability of pavement structure. In this work, the performance degradation of asphalt binder under internal sulfate erosion was investigated. Different dosages of Na2SO4 (0 wt.%, 2.5 wt.%, 5 wt.%, and 10 wt.%) samples were prepared to investigate the effect of sulfate on the performance of the asphalt binder. The surface tension test and low-temperature rheological property test were carried out to evaluate the adhesion of sulfate-incorporated asphalt mastic. Rapid freezing and thawing test with different concentrations of sulfate solution was conducted to explore the effect of sulfate concentrations and freeze-thaw cycles on the softening point and force ductility of matrix asphalt. Phases of the asphalt binder were characterized by Fourier transform infrared (FTIR) spectroscopy. The results show that sulfate has a negative impact on the road performance of the asphalt binder. Internal sulfate erosion decreased the adhesion of the asphalt binder. Also, the low-temperature rheological property of asphalt binder was deteriorated. After the freeze-thaw cycles of external sulfate erosion, softening point and tensile force peak of matrix asphalt increased and the low-temperature ductility decreased. The main reason of performance deterioration of the asphalt binder is the “salt aging” effect causing by sulfate erosion. The research results can provide useful reference for the durability design of asphalt mixture in sulfate-enriched regions.

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Tight reservoirs normally have production problems due to very low matrix permeability and different damage mechanisms during drilling, completion and stimulation operations. These reservoirs have small pore throat size with significant capillary pressure energy suction that imbibes and holds liquid in the capillary pores. Such residues from Guar after gel breaks cause formation damage and low conductivity, and it can significantly reduce well productivity even in tight gas reservoirs. This paper presents a new cellulose derivative of instant dissolution and free of residue. The field test results of the new fluid in tight gas reservoirs in China show importance of minimizing formation damage in a hydraulic fracturing stimulation. Otherwise, the well productivity improvement may not be achieved in the case of excessive residues into formation during hydraulic fracturing operations. A new fluid has been applied in 18 wells in western China and the results show that the new fluid was easy to prepare and rapidly dissolved with no "fish eye", this system can reach 97% of the peak viscosity within 2 minutes, and the surface tension of the gel breaking liquid is 18.44 mN/m. No residue was found after the gel was broken, its conductivity was improved, and the formation damage is less than 13% in the core test. Meanwhile it has excellent properties of proppant suspension. Gas production in multiple wells of the tight gas reservoir increased to 2.13×105 m3/d after stimulation with the new fluid, 4.2 times higher than similar groups of wells using Guar-based fracturing fluids.

Alkaline diagnesis is a diagenetic process that a reservoir undergoes under an alkaline environment. Because of the influence of alkaline formation water, the most typical characteristics of diagnesis is that quartz is obviously dissolved, feldspar is massively enlarged, and less late carbonate cement is formed in the evolution of carbonate minerals. With the decrease of the alkalinity of the formation water in diagenesis, the quartz overgrowths become common. The change in the chemical characteristics of the formation water leads to a more complex distribution of reservoir porosity at different depths than that of the secondary porosity formed by classical acidic water. It also makes the B stage of early diagenesis the important development period of secondary porosity.

OBJECTIVE To study the chemical constituents of aerial parts of Ammopiptanthus mongolicus. METHOD Isolation and purification were carried out on silica gel, Sephadex LH-20 and HPLC column chromatography. The structures of the compounds were identified by physico-chemical properties and spectral analysis. RESULT Nine compounds were isolated and identified as (+)-maackiain (1), brevifolin (2), 7-hydroxy-4'-methoxy isoflavanone (3), daidzein 4',7-diglucoside (4), genistein 4', 7-di-O-beta-D-glucoside (5), isolupalbigenin (6), ononin (7), beta-sitosterol (8), beta-daucosterol (9). CONCLUSION Compounds 2, 4 - 6 were obtained from the genus Ammopiptanthus for the first time.