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Tight oil is widely distributed around the world, and industrialized exploitation has been developed and applied in North America, greatly alleviating the contradiction between supply and demand of energy. The main storage space of tight oil reservoirs is micro-nano pores, and a reliable method for studying the occurrence of tight oil in micro-nano pores has not been studied. In this paper, the microscopic occurrence of tight oils in the Songliao Basin, Ordos Basin, and Tarim Basin in China are studied in combination with nuclear magnetic resonance (NMR) and field emission scanning electron microscopy (FE-SEM) scanning techniques. A method for characterizing the storage space, occurrence state, and influencing factors of tight oil based on SEM and NMR was proposed. The results show that the storage space of tight oil reservoirs is nanoscale cracks and pores. Mainly, these are distributed on the scale of less than 1 μm and more than 10 μm, the volume of porecracks is less than 1 μm, which account for more than 80% of the total volume. This indicates that the tight oil mainly exists in the nanoscale pore throat. The scattered distribution of crude oil in the black shape of oil spot is mainly in the micro-nano pores, and the crude oil content in the micro-cracks is small, indicating that nanoscale cracks are the main space for the occurrence of tight oil. However, some micro-cracks can penetrate oil spots or oil stains, and can connect the oil spots with scattered distribution, which will greatly improve the mobility of crude oil. In addition, oil spot accumulation areas often develop illite and illite/smectite mixed-layer, and clay minerals have developed nanoscale pores. The crude oil and clay minerals have certain associated characteristics. This study is of great significance for understanding the law of the occurrence and migration of tight oil and the basic theoretical research and technological innovation of the development of tight oil reservoir.

In unconventional petroleum reservoirs, such as shale gas, shale oil, tight oil, and tight gas reservoirs, the microscopic pore structure, namely, the size, geometry, distribution, and interconnected relations of the pores and throats of a shale rock, directly affects the porosity, storage, and permeability. Studies related to the microscopic pore structure of shale are considered important for evaluating shale resources and for elucidating their distribution characteristics; additionally, these studies aim to improve the productivity and recovery ratio of both oil and gas. Therefore, methods that can accurately characterize the microscopic pore structure of shale have received considerable attention. In this study, we used the electrodeposition method to fill the interconnected pores of a rock sheet with metal and then used selective dissolution of the rock portion of the rock sheet to obtain the metal complex of the pore-throat structure. The structure and morphology of the obtained metal complex, which represents the microscopic pore structure of the shale, are characterized by a scanning electron microscope (SEM). By combining electrochemical deposition and SEM images, we could directly observe the three-dimensional microstructure of the shale at a scale smaller than 50 nm with a large observation area. Additionally, the surface areas of the connected pores and throats of the shale were calculated.

The aging behaviors of PMMA in liquid scintillator at different temperatures of 30 °C, 40 °C, 50 °C and 55 °C under static tensile stress were experimentally investigated with dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), and the service life of the PMMA was predicted on the basis of the time-temperature superposition approach. The results showed that the higher the aging temperature, the faster the tensile strength of PMMA decreased. Acceleration of aging can be realized by applying high temperatures, and a master curve can be constructed using the time-temperature superposition concept. The linear behavior of the plot of the shift factors versus the inverse aging temperature indicated that the aging mechanism was consistent with Arrhenius's law, and the lifetime of PMMA was predicted to be 25 years at 20 °C. Keywords: PMMA, Tensile stress, Aging, Time-temperature superposition, Lifetime prediction, Liquid scintillator

The microscopic pore structure of unconventional petroleum reservoirs, such as shale gas、 tight oil、tight gas, and so on, namely the size, geometry, distribution, and interconnected relations of the pores and throats of a shale rock, directly affects their porosity, storage, and permeability. Studies related to the microscopic pore structure of shale are considered to be attractive to evaluate the shale resource and to elucidate their distribution law; additionally, studies aim to improve the productivity and recovery ratio of both oil and gas. Therefore, methods that can be used to accurately characterize the microscopic pore structure of shale have received considerable attention. In this study, we combine electrochemical deposition and scanning electrode microscopy to characterize the microscopic pore structure of shale. Therefore, we could directly observe the three-dimensional microstructure of shale that are smaller than 50 nm with a large observing area. Additionally, the surface areas of the connected pores and throats of the shale are calculated.

Photoelectrochemical (PEC) splitting of water into hydrogen and oxygen by the direct use of sunlight is an ideal, renewable method for solar-to-chemical conversion. Photocathodes based on p-type copper oxide (CuO) are promising materials for large-scale and widespread PEC water splitting due to the abundance of copper element, suitable band gap, and favorable band alignments. In this work, we fabricated one-dimensional CuO nanowires on Cu foils via a facile thermal-treatment process for PEC water splitting. The well-defined CuO nanowire-based photocathodes exhibit an obvious photocurrent responsive character of a p-type semiconductor with onset potential at ∼700 mV vs. RHE. The CuO photocathode shows a photocurrent of ∼1.4 mA cm−2 at 0 V vs. RHE under AM 1.5 G irradiation, which is one of the highest photocurrents based on bare CuO photocathode. Further depositing Pt nanoparticles as cocatalyst on the surface of CuO nanowires to accelerate surface reaction and inhibit charge accumulating at semiconductor/solution interface, resulting in a significant improvement of the stability for photoelectrodes. Our work reports a promising method for fabricating well-defined metal oxides-based photoelectrodes, which providing a promising candidate for highly efficient no bias PEC devices for solar fuels production.

Solar-driven water evaporation plays an important role in the recycling of low-energy water resources. Here, we have prepared porous hydrophilic/hydrophobic cellulose graphene aerogel (CGA) to achieve efficient water recycling in solar-driven desalination and purification of heavy metal wastewater. The aerogel can reach water evaporation of 7.2 kg·m-2 for 4 h from simulated or actual seawater under 1 sun irradiation, which meets the daily water demand of two adults. Due to the interfacial evaporation and the formation of hydrogen and chelating bonds between heavy metal ions and oxygen-containing functional groups, CGA can effectively reduce the amount of heavy metal sewage to obtain water without biotoxicity. The efficient water recycling of aerogel is mainly attributed to the photothermal conversion of hydrophobic reductive graphene oxide (rGO), the interconnected porous structure formed by random stacking and cross-linking of hydrophilic cellulose sheets as well as holes in it serve as supply channel of water evaporation. In addition, ambient factors such as wind, humidity and ambient temperature boost the water evaporation of CGA in open system, while in closed system reducing the light reflection of condensed water and the relative humidity of the space is more conducive to improving evaporation efficiency.

Oxygen vacancies can regulate the energy band structure of semiconductor photocatalytic materials, and serve as electron traps and active sites to improve the photocatalytic activity of the photocatalyst. Herein, we prepared Bi2MoO6 flower spheres with a double-layer structure by a simple solvothermal method, and achieved the controllable introduction of oxygen vacancies through subsequent air calcination at different temperatures. The double-layer structure of Bi2MoO6 improved the light absorption because of multiple reflections. Compared with the pristine Bi2MoO6, the introduction of oxygen vacancies regulated the energy band structure of Bi2MoO6, improved the separation and transfer rate of electron-hole pairs, and produced more active species such as h+ and 1O2. Among all samples prepared, BMO-350 had the best activity, which could degrade 90.6% of ciprofloxacin (10 mg/L) within 80 min under the irradiation of 6000 K visible LED light. While under ultraviolet, 3000 K, 4500 K, 6000 K visible, red Led light and xenon lamp irradiation, the CIP degradation efficiency reached 94.9%, 73.77%, 85.9%, 89%, 16.24%, and 94.7%, respectively, demonstrated that the appreciable photocatalytic activity under the low energy light source.

Sulfidated microscale zero-valent iron (SmZVI) attracts much attention recently in remediation of contaminated groundwater, but whether polymer coating on SmZVI would impact on its reactivity and capacity is yet to be understood. In this work, SmZVI was prepared by milling mZVI with elemental sulfur, and its stability in agar solution was evaluated. The impact of polymer coating on SmZVI grains’ capacity and reactivity for chromate reduction was then examined. Experimental results indicated that SmZVI having the best overall performance was attained by grinding mZVI with elemental sulfur at 0.05 S/Fe molar ratio for 10 h. SmZVI’s stability can be substantially improved if dispersed in 2.0 g/L agar solution. Existence of agar films on the SmZVI grain (A-SmZVI) lowered the material’s capacity for chromate reduction by 56%, and the associated reaction kinetics by 70.4%, as estimated by pseudo first-order reaction model using the early-stage experimental data. Analysis of XPS spectra of A-SmZVI post reaction with chromate indicated that multiple reductive species including Fe0, Fe(II), FeS, and S(-II) may have jointly participated in the redox reaction taking place on the A-SmZVI-water interface. Fitting of XPS data supported that S(-II) was oxidized to SO42-, S2O32-, and S0, in order of decreasing surface concentration.

A visible-light responsive self-assembled perylenetetracarboxylic diimide (PDI)/reduced graphene oxide (rGO) composite film was obtained and showed excellent photocatalytic performance and efficient interfacial steam generation. The degree of π-π interactions between Perylenetetracarboxylic diimide supramolecular nanofibers (nano-PDI) and rGO regulated the energy band structure and redox potential of the composite film to produce h+ and O2− active species. The photothermal conversion of the composite film under visible light irradiation was realized, which was mainly because the above-bandgap electrons and holes of the upper nano-PDI relaxed to the edge of the band and converted the excess energy into heat. The unique energy band structure of rGO also promotes the effective photothermal conversion of the composite film. The composite film degraded 94.31 % (10 mg/L) of ciprofloxacin hydrochloride (CIP) under 0.5 sun visible light irradiation within 120 min. The corresponding interfacial steam generation efficiency via photothermal conversion of the composite film was 10.92 %. Furthermore, the composite film retained its excellent photothermal performance, when used to remove CIP from real water samples, including Yellow River water, Weihe River water, and tap water.

Marine biofouling is perplexing the development of marine industry, and the traditional antifouling methods are restricted by the requirements of marine environmental friendliness. Marine bacteria attachment is the initial stage of marine fouling and it can be effectively reduced by reducing bacterial attachment. In this study, two modification methods were reported to synthesize antibacterial surfaces based on the different order of Magainin Ⅱ (MAG Ⅱ) modification. The preparation of SS-DA-M was generated by modifying the 304 stainless steel (304 SS) surface with dopamine firstly and then grafting the MAG Ⅱ onto the dopamine modified surface; SS-M-DA was obtained by modifying 304 SS surface using MAG Ⅱ derivative which synthesized by MAG Ⅱ and dopamine under weak acid condition. XPS, contact angle, film thickness and surface topography analysis showed that both methods grafted MAG Ⅱ onto the 304 SS surface successfully, changing the morphology and wettability of the substrates. Antibacterial results demonstrated that the two modified surfaces possessed strong resistance against V. natriegens, and the antibacterial efficiency of SS-DA-M and SS-M-DA reached 98.07 % and 99.79 %, respectively. Robustness results illustrated that the modified surface could keep strong antibacterial capacity in seawater for a long time. The phy-chemical properties and antibacterial properties of SS-M-DA surface were superior to SS-DA-M surface because more MAG Ⅱ were grafted onto 304 SS surface and the distribution was more uniform than the SS-DA-M surface. The investigation may offer a new and promising strategy to tackle surface fouling of hull, aquaculture cage and other marine facilities.

Fast detection of toxic metals in crops is important for monitoring pollution and ensuring food safety. In this study, laser-induced breakdown spectroscopy (LIBS) was used to detect the chromium content in rice leaves. We investigated the influence of laser wavelength (532 nm and 1064 nm excitation), along with the variations of delay time, pulse energy, and lens-to-sample distance (LTSD), on the signal (sensitivity and stability) and plasma features (temperature and electron density). With the optimized experimental parameters, univariate analysis was used for quantifying the chromium content, and several preprocessing methods (including background normalization, area normalization, multiplicative scatter correction (MSC) transformation and standardized normal variate (SNV) transformation were used to further improve the analytical performance. The results indicated that 532 nm excitation showed better sensitivity than 1064 nm excitation, with a detection limit around two times lower. However, the prediction accuracy for both excitation wavelengths was similar. The best result, with a correlation coefficient of 0.9849, root-mean-square error of 3.89 mg/kg and detection limit of 2.72 mg/kg, was obtained using the SNV transformed signal (Cr I 425.43 nm) induced by 532 nm excitation. The results indicate the inspiring capability of LIBS for toxic metals detection in plant materials.

A large number of micro–nanopores constitute the main reservoir space of shale oil and gas reservoirs. To evaluate a reservoir pore throat system's structure, it is of great significance to quantitatively characterize the pore distribution. There are two commonly used methods for characterizing the pore structure: mercury intrusion and gas adsorption analysis. The mercury intrusion method is to determine the pore size distribution by measuring the amount of mercury in the pores under different external pressure. The detection range of this method is pores with diameters of 3 nm–400 μm, and the optimal detection range is pores with diameters of 100 nm–100 μm. The gas adsorption analysis method is to measure the adsorption amount of nitrogen and other gases at the liquid nitrogen temperature. the optimal detection range of this method is pores with diameters of 0.4–100 nm. Because of the complex structure of porous materials, the results of different experimental methods are inconsistent, and the pore structure information provided by a single method is limited. Since different porous solid materials have different chemical and physical properties and different pore diameter range, it is necessary to select experimental methods for the target material. This paper introduces a new method of measuring pore distribution, which is a Low Field Cryoporometry NMR method. Based on the principle of the nanometer-confined effect, this method can measure mesoporous distribution of different porous materials and shale. The logarithmic pore diameter distribution and the pore diameter distribution histogram indicate that the shale sample's pore volume is mainly comprised of pores with a diameter of 80–500 nm, which is consistent with the pore statistical results of the SEM analysis. The porous size distribution (PSD) was obtained by Croporometry NMR (NMRC) for shale samples, which was compared with that from the measurements by Brunauer-Emmett-Teller Method (BET). This method enlarges the scope of the classical gas adsorption method, then can be used to study pore diameters from 10 nanometers to micron size. Furthermore, it provides an important reference to the study of the pore structure of shale oil and gas reservoirs.

In this contribution, a nano-pore template with controllable pore size was used to simulate pore-throats in shale. Considering the wettability at the solid-liquid contact, the seepage of oil in channels with different pore sizes was examined to figure out the effect of pore diameter on oil storage capacity scientifically and systematically for the first time. The simulation shows that the lower threshold of pore-throat to store oil can be 20nm under certain conditions. The new threshold value of pore size for oil storage has brought about revolutionary changes in the estimation of geologic reserves, recoverable reserves and economically recoverable reserves of shale oil.

Rapid detection of Cd content in soil is beneficial to the prevention of soil heavy metal pollution. In this study, we aimed at exploring the rapid quantitative detection ability of laser- induced breakdown spectroscopy (LIBS) under the conditions of air and Ar for Cd in soil, and finding a fast and accurate method for quantitative detection of heavy metal elements in soil. Spectral intensity of Cd and system performance under air and Ar conditions were analyzed and compared. The univariate model and multivariate models of partial least-squares regression (PLSR) and least-squares support vector machine (LS-SVM) of Cd under the air and Ar conditions were built, and the LS-SVM model under the Ar condition obtained the best performance. In addition, the principle of influence of Ar on LIBS detection was investigated by analyzing the three-dimensional profile of the ablation crater. The overall results indicated that LIBS combined with LS-SVM under the Ar condition could be a useful tool for the accurate quantitative detection of Cd in soil and could provide reference for environmental monitoring.

Rapid detection of soil nutrient elements is beneficial to the evaluation of crop yield, and it’s of great significance in agricultural production. The aim of this work was to compare the detection ability of single-pulse (SP) and collinear double-pulse (DP) laser-induced breakdown spectroscopy (LIBS) for soil nutrient elements and obtain an accurate and reliable method for rapid detection of soil nutrient elements. 63 soil samples were collected for SP and collinear DP signal acquisition, respectively. Macro-nutrients (K, Ca, Mg) and micro-nutrients (Fe, Mn, Na) were analyzed. Three main aspects of all elements were investigated, including spectral intensity, signal stability, and detection sensitivity. Signal-to-noise ratio (SNR) and relative standard deviation (RSD) of elemental spectra were applied to evaluate the stability of SP and collinear DP signals. In terms of detection sensitivity, the performance of chemometrics models (univariate and multivariate analysis models) and the limit of detection (LOD) of elements were analyzed, and the results indicated that the DP-LIBS technique coupled with PLSR could be an accurate and reliable method in the quantitative determination of soil nutrient elements.

With increasing environmental awareness, novel strategies to effectively separate oil from industrial wastewaters and polluted oceanic water are highly desired. Using special wettability to design new materials for oil/water separation is an effective and facile way. Herein, polyimide (PI) aerogel is designed and prepared by freeze-drying PI precursor poly(amic acid) ammonium salt (PAS) water solution followed by imidization. With high hydrophobicity, the PI aerogel can be used for the absorption and separation of oil and water. 30–195 times weight of organic pollutants and oils can be absorbed by PI aerogel. To demonstrate the cyclic distillation test, cyclohexane was absorbed by the PI aerogel. As the size and the porosity structures of PI aerogel stayed the same during the separation/distillation cycles, no obvious change in absorption capacity was found after five cycles, indicating the highly stable recycling performance. During separation, water quickly permeated through the PI aerogel and dropped into the beaker below, while oil was retained above it and no external force was employed. Additionally, PI aerogel is also usable under harsh conditions. This research paved the way for fabricating high efficient and recyclable oil/water separation PI aerogel which can be used in the petroleum industry in the future.