MXene, as a new 2-dimensional (2D) material, has excellently potential applications in the field of electrochemistry owing to its high conductivity and fast charge transporting speed. Especially, ...MXene/polymer composites have attracted widely attentions due to their extensive application in the area of multi-functional materials. Herein, the composites of Ti3C2Tx MXene/polyaniline (PANI) with different PANI contents have been successfully prepared. The microwave absorption mechanism of these materials was investigated. Attributing to the multiple layer structure, the dielectric property of Ti3C2Tx MXene and PANI, and the synergistic effect between the Ti3C2Tx and PANI, the as-prepared composites possessed a specific microwave absorbing behavior. With a proper content of PANI, the MXene/PANI composites in a paraffin matrix exhibited a maximum reflection loss of −56.30 dB at 13.80 GHz with the thickness of 1.8 mm. In addition, the effective absorption bandwidth (>90%) ranged from X-band (8–12.4 GHz) to Ku-band (12.4–18 GHz) with the tunable thickness ranging from 1.5 to 2.6 mm. The results indicate that MXene/PANI composites has great potential to be used in the field of microwave absorption.
•The synergetic effects of GO and PVP on membrane performance were investigated.•The surface hydrophilicity of membrane was enhanced by the synergistic effects.•The anti-fouling performance was ...obviously improved in PVDF/GO/PVP membrane.•The optimized performance can be obtained at the stipulated GO and PVP contents.
Membrane surface and cross-sectional morphology created during membrane formation is one of the most essential factors determining membrane separation performance. However, the complicated interactions between added nanoparticles and additives influencing membrane morphology and performance during building membrane architectures had been generally neglected. In this study, asymmetric PVDF composite ultrafiltration (UF) membranes containing graphene oxides (GO) were prepared by using N-methyl pyrrolidone (NMP) as solvent and polyvinylpyrrodione (PVP) as the pore forming reagent. In the first time, the effects of mutual interactions between GO and PVP on membranes surface compositions, morphology and performance were investigated in detail. The variation in chemical properties of different membranes and hydrogen bonds in the membrane containing GO and PVP were confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle (CA) were utilized to clarify the synergetic effects of GO and PVP on morphologies and surface hydrophilicity of membranes. Besides, water flux, bovine serum albumin (BSA) rejection and attenuate coefficient were also determined to investigate filtration performance of various membranes. Compared with pure PVDF membrane, the comprehensive performance of PVDF/GO/PVP membrane has been obviously improved. The surface hydrophilicity and anti-fouling performance were enhanced by the synergistic effects of incorporated GO and PVP. When the PVP content was 0.25wt.% and the GO content was 0.5wt.%, the optimized performance can be obtained due to the formation of hydrogen bonds between GO and PVP.
Metal and metalloid nanoparticles (NPs) have attracted substantial attention from research communities over the past few decades. Traditional methodologies for NP fabrication have also been intensely ...explored. However, drawbacks such as the use of toxic agents and the high energy consumption involved in chemical and physical processes hinder their further application in various fields. It is well known that some bacteria are capable of binding and concentrating dissolved metal and metalloid ions, thereby detoxifying their environments. Bioinspired fabrication of NPs is environmentally friendly and inexpensive and requires only low energy consumption. Some biosynthesized NPs are usually used as heterogeneous catalysts in environmental remediation and show higher catalytic efficiency because of their enhanced biocompatibility, stability and large specific surface areas. Therefore, bacteria used as nanofactories can provide a novel approach for removing metal or metalloid ions and fabricating materials with unique properties. Even though a wide range of NPs have been biosynthesized, and their synthetic mechanisms have been proposed, some of these mechanisms are not known in detail. This review focuses on the synthesis and catalytic applications of NPs obtained using bacteria. The known mechanisms of bioreduction and prospects in the design of NPs for catalytic applications are also discussed.
Lacustrine carbonate-rich shales are well developed within the Mesozoic-Cenozoic strata of the Bohai Bay Basin (BBB) of eastern China and across southeast Asia. Developing an understanding of the ...diagenesis of these shales is essential to research on mass balance, diagenetic fluid transport and exchange, and organic-inorganic interactions in black shales. This study investigates the origin and distribution of authigenic minerals and their diagenetic characteristics, processes, and pathways at the scale of lacustrine laminae within the Es4s-Es3x shale sequence of the BBB. The research presented in this study is based on thin sections, field emission scanning electron microscope (FESEM) and SEM-catholuminescence (CL) observations of well core samples combined with the use of X-ray diffraction (XRD), energy dispersive spectroscopy, electron microprobe analysis, and carbon and oxygen isotope analyses performed using a laser microprobe mass spectrometer. The dominant lithofacies within the Es4s-Es3x sequence are a laminated calcareous shale (LCS-1) and a laminated clay shale (LCS-2). The results of this study show that calcite recrystallization1 is the overarching diagenetic process affecting the LCS-1, related to acid generation from organic matter (OM) thermal evolution. This evolutionary transition is the key factor driving the diagenesis of this lithofacies, while the transformation of clay minerals is the main diagenetic attribute of the LCS-2. Diagenetic differences occur within different laminae and at variable locations within the same lamina level, controlled by variations in mineral composition and the properties of laminae interfaces. The diagenetic fluid migration scale is vertical and responses (dissolution and replacement) are limited to individual laminae, between zero and 100 μm in width. In contrast, the dominant migration pathway for diagenetic fluid is lateral, along the abrupt interfaces between laminae boundaries, which leads to the vertical transmission of diagenetic responses. The recrystallization boundaries between calcite laminae act as the main migration pathways for the expulsion of hydrocarbons from these carbonate-rich lacustrine shales. However, because the interaction between diagenetic fluids and the shales themselves is limited to the scale of individual lamina, this system is normally closed. The occurrence of abnormal pressure fractures can open the diagenetic system, however, and cause interactions to occur throughout laminae; in particular, the closed-open (C–O) diagenetic process at this scale is critical to this shale interval. Multi-scale C–O systems are ubiquitous and episodic ranging from the scale of laminae to the whole basin. Observations show that such small-scale systems are often superimposed onto larger ones to constitute the complex diagenetic system seen within the BBB combining fluid transport, material and energy exchange, and solid-liquid and organic-inorganic interactions.
The black shale of the Upper Ordovician and Lower Silurian is a significant target for shale gas exploration in the Southern Sichuan Basin. In this study, we introduced a lithofacies classification ...for shale based on rock mineral composition. Because the pore structure of gas shale reservoirs are complex and greatly affect the gas storage and transport in shale, four different methods of low-pressure nitrogen gas adsorption, high-pressure mercury intrusion, scanning electron microscopy (SEM) and gas expansion methods were used to investigate the reservoir pore structure and storage space. Combined with X-ray diffraction, total organic matter content (TOC), gas content, methane adsorption, porosity and permeability and wireline data, the key factors that affect shale gas content and storage of shale gas were analyzed.
According to our shale classification, three main lithofacies, i.e., calcareous mudstone (CM), high calcareous mixed mudstone (HCMM) and low calcareous mixed mudstone (LCMM), were identified in our study area. The experiment indicates that the shale has a high TOC, thermal maturity and gas content. The methane adsorption isotherms show that the sorbed gas content has a positive correlation with TOC. Difference of TOC between the three is small. Nitrogen adsorption indicates that mesopores dominate the shale pore composition and organic matter is the main source of mesopores. Mercury injection shows that the macropore volume accounts for approximately 14–22% of the total pore volume. No obvious pore structure differences were found for different lithofacies. However, taking the porosity into consideration, LCMM has the largest macropore volume. The SEM observations revealed that organic matter pores, interparticle pores and intraparticle pores are the main pore types. Interparticle pores mainly develop in LCMM which has a relatively high quartz and low carbonate content, it may be the major reason for high porosity, high macropore volume, and high free gas content of LCMM. Free gas and absorbed gas are the major storage form of shale gas. Given similar temperature and pressure conditions, the total organic matter content is the major factor that affects the adsorbed gas content. Therefore, with high free gas and adsorbed gas content, LCMMs with high total organic matter contents would be the most favorable type of lithofacies in this region.
•A lithofacies classification for shale based on rock mineral composition is introduced.•Four methods were used to investigate the reservoir pore structure and storage space of three lithofacies.•Mesopores dominate the shale pores and organic matter is the main source of mesopores.•Low calcareous mixed mudstone with high total organic matter content is the most favorable lithofacies.
Fibrous carbon materials have been attracted many researchers' attentions. Carbon fibers have been developed as one of the most important industrial materials for modern science and technology since ...1960s 1. Due to the superior mechanical properties including high-specific strength and modulus, low density and thermal expansion, heat resistance, and chemical stability, carbon fibers as reinforcement materials have provided the impetus for researchers in developing high-performance composite materials. Nowadays, carbon fiber reinforced plastics (CFRP) are widely applied in the industries of aeronautic, aerospace, sporting goods, as well as new energy.
The region between the fibers and matrix, contains unique micromechanical properties, is characteristically called the interphase and influence the bulk composite properties. Interface between fibers (reinforcements) and matrix is an important component for CFRP which may govern the CFRP performances 2. For example, the interphase determines the off-axis strength and impact toughness of CFRP, environmental stability of CFRP and functional performance of CFRP. The effect of interface on composite can be achieved by regulating the composition, structure and distribution of the interface 3. It has been proved that there has an optical interface for polymer based composite through the match of composite interface, reinforcement and polymer matrix. However, in terms of the smooth surface and chemical inertness of carbon fiber, the interface between carbon fiber and resin matrix is unsatisfactory. The interface should be modified and carefully controlled, which can be through by increasing the surface polarity of carbon fiber, improving the wettability between carbon fiber and resin, as well as promoting the chemical reaction. Obey these principles, the interfacial modification methods have been well developed.
The universality of carbon fiber and polymer matrix, and the variability of the composite material forming process result in the complexity of polymer-based composites interface problems. Meanwhile the scale of the interface region is very small, it has great difficulty in characterizing the chemical structure, physical properties and mechanical characteristics. Recently, a series of effective characterization methods have been developed and initial interface characterization system is always being improved. With interface characterization techniques, the interfacial composition, structure morphology and micro-mechanical characteristics of interface can be researched easily, which can provide the basis for studying the interface physical and chemical properties. Hence interface characterization techniques not only are theory researches, but also have important practical significance for solving practical application problems of carbon fiber composites. Interface characterization techniques have become an important research direction of interface engineering research.
In this paper, the researches in this field of carbon fiber interface were described, such as carbon fiber composite material characterization methods, interface control, and interfacial modification methods. With reference to the research achievements of a large number of scholars at present, so their current development trend were systemic concluded.
Debris avalanche deposits are developed on slopes in various environments, including submarine volcanoes, continental volcanoes, continental slopes, and mountain ranges. In contrast, research is ...relatively scarce on the coarse-grained subaqueous debris avalanche deposits formed by the collapse of steep basin margins in continental small rift basins, which are controlled by tectonics. Through the interpretation of satellite imagery, field investigations, and the study of the morphological characteristics and internal structures of sediments, a massive debris avalanche event during the Early Cretaceous, Xiguayuan Formation of the Luanping Basin at the northern edge of the Yanshan tectonic belt on the North China Block, named the Wangying Debris Avalanche Deposit (WYDAD), has been identified and analyzed for its kinematics, dynamics, and long-runout mechanisms. The study reveals that based on sedimentology, internal structures, and basal characteristics, five different types of sedimentary morphologies can be identified from the source zone to the distal zone: convergent ridges and grooves (longitudinal expansion and lateral compression), transverse ridges and grooves (compression), longitudinal ridges and grooves (shearing and stretching), arcuate ridges and grooves (compression), and mixed sediments (radial extension). The grain size of coarse-grained debris avalanche deposits decreases with increasing transport distance and fragmentation due to jigsaw cracking, while matrix content increases. Additionally, the entrainment of fine-grained substrate and the mixing of lake waters during the transport of debris avalanches often evolve into secondary debris flows or high-density turbidity currents. Debris avalanches are likely primarily controlled by regional tectonic activity and volcanic action. Compared to subaerial debris avalanche deposits, the subaqueous WYDAD exhibits characteristics such as low fragmentation, smooth underwater terrain due to water resistance and buoyancy, and higher fluidity. The mechanism for the long-distance, high-speed transport of the WYDAD is explained by “hydroplaning” and high pore pressure generated by non-draining shear. This study provides insights into the transport processes of coarse-grained subaqueous debris avalanche deposits in continental rift basins. It verifies whether such sediments can serve as a primary sedimentary system for CCUS or potential resource storage.
The upper fourth member of the Eocene Shahejie Formation (Es4s) is a typical example of a Bohai Bay Basin lacustrine shale. These sedimentary units are characterized by markedly different mineral ...compositions compared to marine siliciclastic shales. Thus, understanding the characteristics and sedimentary environment of lacustrine shales enables analysis of their origin, enrichment of organic matter (OM), distribution of organic rich shales, and exploration targets for shale oil and gas. Based on thin sections and field emission scanning electron microscope observations from well core samples, combined with X-ray diffraction and geochemistry, the mineralogy, lithofacies, organic and geochemical characteristics as well as the sedimentary environment of the Es4s shale are analyzed in this paper. The results show that, across the study area, the Es4s shale is mainly composed of calcite, clay minerals, and quartz, but also contains subordinate dolomite, feldspar, pyrite, and anhydrite. On the basis of mineral composition, total organic carbon (TOC) content and sedimentary structures, eight lithofacies are identified. The TOC content of samples ranges between 0.15% and 11.4%, with an average of 2.27%, while OM primarily consists of Type I kerogen. Based on paleoclimate and paleosalinity data as well as redox conditions and primary productivity, the sedimentary environment of the Es4s shale can be further divided into four intervals: Intervals I, II, III, and IV, and these four intervals have large differences, rather than persistently warm-damp climate and reducing condition. The evolution of these intervals is also analyzed in detail in this study, and the controls on lithofacies and OM accumulation are also discussed. The results of this study suggest that the development of mineral compositions and frequent vertical lithofacies associations are strongly controlled by the cyclic evolution of the sedimentary environment. Thus, the accumulation of OM occurs as the result of a number of inter-connected factors including primary productivity, terrestrial inputs, and variation in oxidizing-reducing conditions. Across a given interval, these factors can either work together, or one can play a leading role.
•Petrology and geochemistry characteristics of Es4s shale are detailed analyzed.•Sedimentary environment of different intervals has been detailed analyzed.•The sedimentary environmental controlling on petrology and organic matter accumulation has been discussed.
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