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Previous studies on graptolites have mainly focused on stratigraphic division and sedimentary environment analysis. On the basis of previous studies of Ordovician and Silurian graptolites in the Middle–Upper Yangtze region, this paper makes full use of core analysis, drilling geological, experimental analysis, and logging data from wells and combines graptolite types in different sedimentary environments to identify 4 graptolite zones, WF1–WF4, and 9 graptolite zones, LM1–LM9, in the Silurian Longmaxi Formation in the Middle–Upper Yangtze region, among which WF2–LM4 present high total organic carbon (TOC), organic pore development, and shale gas enrichment and are favorable development zones. This study reveals that enrichment in graptolites has positive correlations with TOC, organic porosity, and total hydrocarbon content. The evolution of graptolites has contributed to the enrichment in organic matter and the formation of organic pores in shales and affects shale gas–bearing properties to a certain extent, which is an important indicator for shale gas reservoir evaluation.

An intelligent fault detection and classification for abnormal current data of transmission lines is proposed. According to the monthly report and the abnormal condition information stored in the system, four kinds of abnormal state data are chosen. By extracting three fault features of data, combining k-means algorithm and TSNE dimensionality reduction algorithm, fault categories can be clearly and intuitively distinguished, and the purpose of intelligent alarm for abnormal state current is realized.

The origin of the organic-rich shale in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation is complex and controversial. This paper reports the geochemical data of Wufeng-Longmaxi Formations in the Upper Yangtze region to restore the paleoenvironment and explore the accumulation mechanism of organic matter. The total organic carbon (TOC) content of the Wufeng Formation was relatively high, with an average of 2.86%. The Lower Longmaxi Formation showed the highest TOC content, with an average of 3.99%, and the upper part was a continuously low value with an average of 1.22%. The paleoproductivity proxies (Babio, Cu/Al, Ni/Al, Siexcess) showed that in the Katian and Rhuddanian-Aeronian Stages, the Upper Yangtze Sea had high primary productivity, indicating that organic matter accumulation was more affected by terrigenous influx and redox conditions. Al, Zr, and Zr/Al indicated that terrigenous influx was relatively high in the Kaitian-Hirnantian Stages, it was at a constant low in the Rhuddanian Stage, and increased again in the Aeronian Stage. The correlations between redox-sensitive trace elements (Mo, U, V) and TOC indicate that the organic-rich shale of the Wufeng Formation was deposited in the anoxic&ndash, euxinic environment. In the Longmaxi Formation, organic-rich shales formed in a more hypoxic environment, and overlying organic-lean shales formed in a suboxic environment. Therefore, the anoxic&ndash, euxinic conditions of the Late Ordovician Yangtze Sea were the main reason for the organic matter accumulation, but the high terrigenous influx caused by regression and/or structural controls diluted the organic matter to some extent. For the Early Silurian, a complete transgression&ndash, regression cycle changed terrigenous influx and redox conditions, resulting in significant differences in organic matter accumulation.

In order to effectively evaluate shale gas reservoirs with low porosity, extra-low permeability, and no natural productivity, dipole array acoustic logging, which can provide various types of information including P-wave slowness (DTC) and S-wave slowness (DTS), is widely used. As the dipole array acoustic logging tool has a larger investigation depth and is suitable for complex borehole environments, such as those with a high wellbore temperature, high drilling fluid column pressure, or irregular borehole wall, it has been mainly applied to the evaluation of lithology, gas potential, fractures, and stimulation potential in shale gas reservoirs. The findings from a case study of the Sichuan Basin in China reveal that the acoustic slowness, S-P wave slowness ratio (RMSC), and S-wave anisotropy of the dipole array acoustic logging can be used to qualitatively identify reservoir lithology, gas potential, and fractures. Using the relationship between DTC and the total porosity of shale gas reservoirs, and combined with the compensated neutron (CNL) and shale content (Vsh) of the reservoir, a mathematical model for accurately calculating the total porosity of the shale gas reservoir can be established. By using the relationship between the RMSC and gas saturation in shale gas reservoirs and tied with density log (DEN), a mathematical model of gas saturation can be established, and the determination of gas saturation by the non-resistivity method can be achieved, delivering a solution to the issue that the electric model is not applicable under low resistivity conditions. The DTS, DTC, and DEN of shale can be used to calculate rock mechanic parameters such as the Poisson’s ratio (POIS) and Young’s modulus (YMOD), which can be used to evaluate the shale stimulation potential.

Control and manipulation of single charges and their internal degrees of freedom, such as spins, is a fundamental goal of nanoscience with promising technological applications. Recently, atomically thin semiconductors such as WSe$_2$ have emerged as a platform for valleytronics, offering rich possibilities for optical, magnetic and electrical control of the valley index. While progress has been made in controlling valley index of ensemble of charge carriers, valley control of individual charges, crucial for valleytronics, remains unexplored. Here, we provide unambiguous evidence for localized holes with net spin in optically active WSe$_2$ quantum dots (QDs) and control their spin-valley state with the helicity of the excitation laser under small magnetic field. We estimate a lower bound on the valley lifetime of a single charge in QD from recombination time to be $\sim$ nanoseconds. Remarkably, neutral QDs do not exhibit such a control, demonstrating the role of excess charge in prolonging the valley lifetime. Our work extends the field of 2D valleytronics to the level of single spin-valley, relevant for quantum information and sensing applications

The advanced oxidation technology dominated the disposal of reverse osmosis concentrate in textile and dyeing industry due to its extremely low biodegradability. For resource conservation and sustainable development, the reverse osmosis concentrate was reused in dyeing procedure after being treated properly with combining method of persulfate oxidation and lime-soda softening. Firstly, the refractory organics was oxidized by persulfate thermal activation and the results indicated that the most efficient and economical reaction happened with initial pH = 5.0, 1000 mg/L initial persulfate concentration and 75 °C. In this process, chemical oxygen demand degradation fitted the pseudo-first-order model well and the sodium sulfate concentration increased from 9600 to about 10,350 mg/L. Then, the hardness of reverse osmosis concentrate including Ca 2+ and Mg 2+ hardness was softened efficiently by lime-soda softening technology and appropriate lime and soda concentration was determined to be 150 mg/L and 800 mg/L, respectively. Finally, the effluent was employed as the dyeing water to test the reuse feasibility in dyeing of reactive dyes. Color strength, color difference and color fastness were all used to evaluate the dyeing performance and dyeing results showed that the effluent which was treated properly (COD ≤ 21.5 mg/L, total hardness ≤17.0 mg/L) was available for reuse in reactive dyes dyeing procedure. The study provided a novel method to treat and reuse reverse osmosis concentrate and more importantly, it promoted sodium sulfate concentration and saved its supplementation and dyeing cost in dyeing procedure.

A large volume of water is required in shale gas development, especially for large-scale hydraulic fracturing in horizontal wells. This study focuses on 334 shale gas wells in the largest production field Fuling in China. Models are formulated to estimate the water use at each stage of the development process, including pre-drilling preparation, drilling and cementing, fracturing, gas testing, production testing. Domestic water used by employee community of shale gas companies are also fully considered. The results show that the average fracturing water use per well was 34,756.0 m3 in Fuling, which accounted for 98% of the total water use. By the end of 2017, the total fracturing water used in Fuling was 1.09 × 107 m3, and a total of 2.28 × 106 m3 of flowback fluid was achieved with 2.16 × 106 m3 of water reused. In addtion, the domestic water used by the employee community was found to be 2.19 × 106 m3, which was equivalent to the water saved from the flowback fluid. China’s special “development campaign” mode for shale gas extraction is the reason. The results improve the understanding of water use in China’s shale gas development and also provide important implications for water management.

Herein, fabrication of polyurethane glucose sensor membranes doped with next generation biocompatible macromolecular nitric oxide-releasing scaffolds (hyperbranched polyesters, hyperbranched polyurethanes, alginate) was reported. Nitric oxide-releasing S-nitrosothiol-modified hyperbranched polyesters-doped membranes achieved extended nitric oxide-release (> 48 h) and promising in vitro sensor performance (sensitivity 20.9 nA/mM, linear dynamic range 0 – 15 mM). Nitric oxide-releasing N-diazeniumdiolate-modified hyperbranched polyurethanes-doped membranes showed desirable smooth membrane morphology, but had relatively limited nitric oxide-releasing duration (up to 18 h) and half-life (~ 0.4 h). Nitric oxide-releasing N-diazeniumdiolate-modified alginate-doped membranes showed significantly longer nitric oxide-releasing half-life (~ 1.2 h) with hyperbranched polyurethanes, but their nitric oxide-releasing duration (< 20 h) was still limited. Challenges for future studies on this subject lie in extending the nitric oxide-releasing lifetimes of the membranes and obtaining more control over the nitric oxide-release kinetics.