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Enhanced interfacial polarization is one of the most effective methods for efficient electromagnetic wave absorbing (EMA) performance. In this study, we propose a cladding morphology modulation strategy for preparing high-performance PPy/MWCNTs(PC) by controlling the polymerization cladding morphology of PPy through acid doping using an in-situ polymerization method. By constructing a 3D network structure with a rough surface, many interfaces and pore spaces are generated to increase the multiple reflections and scattering of electromagnetic wave energy, improve the interfacial polarization of the material, and enhance the polarization relaxation process. Meanwhile, the 3D conductive network generated by the cladding provides a channel for electron transfer between MWCNTs and PPy nanoparticles and PC nanorods, which improves the conductivity loss of the material and allows more electromagnetic wave to be dissipated in the form of thermal energy. With the doping acid of p-toluene sulfonic (TsOH), the EMA absorption performance of PC composites can reach a maximum reflection loss( RL min ) of -60.21 dB at the frequency of 8.24 GHz, and the best effective bandwidth (EABmax) of 5.04 GHz for single thickness and 14.08 GHz for full-thickness (EABsun), providing excellent EMA performance. [ABSTRACT FROM AUTHOR]

Robust adhesion is crucial for ionic hydrogels in flexible electronic pressure and strain sensors. Herein, we design a transparent and strong adhesion electronic pressure and strain sensor based on a multifunctional ionic hydrogel with double network using polyacrylamide (PAM) and gum arabic (GA). First, the effect of ionic type on the mechanical properties of hydrogels was measured. The GA/PAM–Fe3+ hydrogel with high extensibility (1835%) and toughness 1. 47 MJ / m 3 was selected as the best sensor material. Moreover, the GA/PAM–Fe3+ hydrogel has good adhesion property with various substrates, and the maximum peel strength of the hydrogel to skin could reach up to 123.9 N/m. Furthermore, the resistance of GA/PAM–Fe3+ hydrogel is sensitive to a wide strain window and the gauge factor shows stable and reliable change during deformation. Due to its compliant and excellent adhesive properties, strain sensors based on this hydrogel can be well fixed on the epidermis without adhesive tape, and can perceive large and gentle body movements. These characteristics demonstrate that GA/PAM–Fe3+ hydrogel is promising for a broad range of practical applications in wearable sensors. [ABSTRACT FROM AUTHOR]

Phenol–formaldehyde resin can be used to improve oil recovery; its key lies in its aggregation behavior and blocking strength. However, the traditional phenol–formaldehyde resin used in the petroleum field is all prepared by phenol and formaldehyde. In order to get rid of the dependence on fossil resources and make full use of renewable biomass resources, we used the abandoned walnut shells of the unique agricultural and forestry crops in Gansu province, which contains lignin partially replaced phenol to synthesize the new sulfonated lignin-based phenol–formaldehyde resin (SLPFR). The results showed that the optimum conditions for microwave polymers were polystyrene substitution rate of 20 wt%, decomposition temperature of 160 ℃, decommissioning time of 20 min, and sodium hydroxide concentration of 0.3 mol/L. Infrared spectroscopes and scanning telescopes have shown that after disintegration, there was an increased concentration of phosphorus, which had more active spots and was more suitable for replacing phenylphenol-synthetic formaldehyde resins. LC–MS indicated the molecular mass of SLPFR and the possible structure of molecules, indicating the successful synthesis of SLPFR. In this work, the aggregation behavior and dispersion stability of SLPFR were investigated from the composition of formation water. The effects of metal cations (Na+, Mg2+, Ca2+) on the dispersion stability of SLPFR in formation water were determined by turbidimetry, and the effects of metal cations on the particle size and zeta potential of the SLPFR system were measured by dynamic light scattering method and electrophoretic light scattering method. The stability of the aggregate structure of the SLPFR system was calculated by combining the fractal dimension. In this paper, the surfactant + SLPFR system and partially hydrolyzed polyacrylamide (HPAM) + SLPFR system were designed for the specific conditions of oil reservoirs, and the effects of metal cations on the aggregation behavior and dispersion stability of these two systems were studied. Based on the above comprehensive analysis, aggregation models were constructed to describe the aggregation behavior and dispersion stability of the HPAM + surfactant + SLPFR system. This makes it possible to predict in real time the migration and plugging of SLPFR aggregates in formation water. [ABSTRACT FROM AUTHOR]

Carbon-based hydrogels have emerged as a promising material for wearable strain and pressure sensors due to their excellent conductive and mechanical flexibility. However, some shortcomings such as limited stretchability and susceptibility to phase separation have led to a narrow range of applications. In this study, a GPEC hydrogel was prepared by incorporating metal ions and oxidized multi-walled carbon nanotubes (oxCNTs) into a double-network (DN) hydrogel consisting of gum arabic (GA) and a copolymer polymerized by acrylamide (AM), acrylic acid (AA) and N-methylolacrylamide (NMAM). The uniformly distributed oxCNTs and metal ions formed a three-dimensional (3D) structure of the hydrogel through a large amount of metal complex bonds and hydrogen bonds. The strong interaction improved the mechanical properties of the hydrogels, with an elongation at break of 1957% and a strength at break of 915 kPa. Furthermore, the hydrogels exhibited excellent self-adhesive and self-healing properties. The hydrogel also exhibits high conductivity due to the embedded metal ions and oxCNTs forming a conductive network. The as-prepared strain sensor revealed ultra-high sensitivity (GF = 3.08) and fast response (72 ms). Moreover, the GPEC hydrogel exhibits high pressure sensitivity (2.27 kPa−1 in the range of 0–10 kPa and 0.08 kPa−1 in the range of 20–80 kPa) when assembled into a pressure sensor. Consequently, the GPEC hydrogel sensor could be used to monitor the full range of human motion and could be incorporated into pressure sensing devices for handwriting recognition. Research highlights: The oxCNTs are uniformly dispersed in the GA solution via the hydrogen bonding and hydrophobic polypeptide chain. The GPEC hydrogel was fully physically cross-linked. The extensive physical and chemical interactions result in the GPEC hydrogel exhibiting favorable mechanical properties, self-adhesive characteristics, and self-healing properties. The incorporation of LiCl and EG into the GPEC hydrogel conferred upon it remarkable environmental stability. The GPEC hydrogel-based sensor exhibits both strain and pressure sensing properties. [ABSTRACT FROM AUTHOR]

Conductive hydrogels with adjustable mechanical properties, good flexibility, and high sensitivity are considered to be promising and reliable materials for next-generation wearable devices. To enhance the mechanical properties of hydrogels, double-network (DN) strategy was always brought in hydrogel preparation. However, chemical crosslinks in DN hydrogel will lead to lack self-recovery properties and biocompatibility. Thus, we developed a fully physical crosslinked DN gel by a large quantities of metal chelation and hydrogen bonds by adding ions in mixture of gum arabic (GA) and copolymer polymerized by acrylamide (AM), acrylic acid (AA), and N-Methylolacrylamide (NMAM). This hydrogel (we named GPFE gel) exhibited excellent mechanical properties such as superb tensile strain (2340%), tensile strength (198 KPa), and high toughness (1.59 MJ/m3). Besides, benefiting from the large number of hydrogen bonds brought by the introduction of EG, GPFE gel also showed intriguing self-healing property (97.0% healing efficiency after 2 h), adhesive property (both in the air and underwater), and environmental stablity (could be used normally at –20 °C). Wearable flexible sensors prepared directly from GPFE gel can sensitively monitor both daily activities and slight physiological movements, exhibiting high sensitivity (GF = 2.16) and a wide strain detection window (to eleven times the original length). Therefore, the prepared GPFE gel as a high-performance wearable flexible sensor in this study shows tremendous potential applications in a complex environment. Highlights: The GPFE gel was a fully physical crosslinked double-network (DN) hydrogel with excellent mechanical properties. The addition of GA to the GPFE gel served to render it transparent while simultaneously conferring upon it the desirable properties of self-adhesion, both in the air and underwater. The GPFE gel exhibited an intriguing self-healing property, with 97.0% healing efficiency observed after 2 h. The GPFE gel demonstrated environmental stability, with no adverse effects observed when used at temperatures as low as –20 °C. The GPFE gel exhibited high sensitivity (GF = 2.16) with a wide strain detection window (to eleven times the original length). [ABSTRACT FROM AUTHOR]

Water injection demand for oilfields varies greatly in different development periods. The topology and size of the water injection pipeline network should match the changing demand. Long-term benefits should be considered to avoid the frequent expansion of the network. This paper considers the water demand in multiple periods and develops an MINLP model to optimise the layout and size of the water injection pipeline network for existing pipeline networks. The model aims to minimise construction cost and operating cost. Both pipeline transport and truck transport are considered with pressure constraints, pipeline pressure drop constraints, flow constraints, and supply–demand balance constraints. A piecewise linearisation method is proposed to avoid nonlinear terms in pressure drop and cost constraints. A case from an oilfield in Northwest China is taken as an example to verify the model. The water injection planning of an existing water pipeline network in the future three periods is determined. The results show that 14.6% of the total cost can be saved in the final phase compared to the first phase, which mainly benefited from the reduction of truck transported water volume. [ABSTRACT FROM AUTHOR]

Phenol-formaldehyde resins combined with polymers have a wide range of industrial applications as plugging agents for profile control and enhanced oil recovery. Due to the structural resemblance between lignin and phenol, there are possibilities for environmentally friendly phenol-formaldehyde resin manufacturing. Sulfonated lignin–based phenol-formaldehyde resin was synthesized by partially replacing phenol with lignin, which improved the utilization rate of lignin and achieved the purpose of environmental preservation and resource conservation. Partially hydrolyzed polyacrylamide is the most widely used polymer in chemical methods for enhanced oil recovery. However, the stability of reservoirs with high salt and high temperatures is weak under these conditions. To solve the problem of low oil recovery in high-salt reservoir environments, polymer flooding is adopted, which utilizes high-molecular-weight polymers to raise the viscosity of injected fluids, thereby improving sweep efficiency and altering mobility ratio between oil and injected fluid. We focus on the stability study of different molecular weights partially hydrolyzed polyacrylamide combined with sulfonated lignin – based phenol-formaldehyde resins in metal ions and surfactants. The zeta potential and hydrodynamic diameter of the partially hydrolyzed polyacrylamide – sulfonated lignin – based phenol-formaldehyde resin system in Ca2+ were measured by dynamic light scattering and static light scattering, and the dispersion stability was analyzed. The interfacial energy – modified DLVO theory was introduced to evaluate the stability of its colloidal solution, which made it possible to predict the aggregation behavior of sulfonated lignin – based phenol-formaldehyde resin and the co-migration process of metal cations in real time. [ABSTRACT FROM AUTHOR]

Enhanced oil recovery research focuses on the phenol–formaldehyde resin (PFR) solution (EOR). We studied PFR's morphology and aggregation kinetics at various pH levels. A hydrated layer formed on the surface of PFR as a result of hydrogen bonding between the hydroxyl and phenolic hydroxyl groups and water molecules. We quantitatively quantified the impact of pH on the morphology and aggregation kinetics of PFR by incorporating the hydrated force into the DLVO (Derjaguin Landau Verwey Overbeek) theory. We were able to predict the situation of aggregates plugging into the reservoir by altering the size of PFR aggregates in a capillary. [ABSTRACT FROM AUTHOR]

The stability of phenol–formaldehyde resin (nHAP) in the oil displacement process influences its flooding and profile control capabilities. There aren't many studies that compare how various surfactants affect PFR stability. The surfactants CTAB, Tween 60, and SDS were selected as representative ones. To look at the changes in stability, spectral turbidity and dynamic light scattering experiments were employed. It was found that the cationic surfactant CTAB can connect with the surface of PFR, just as metal cations, lowering electrostatic repulsion and facilitating the aggregation of PFR composite molecules. Anionic and nonionic surfactants both have some degree of system stability stabilizing properties. When Tween 60 and SDS adsorbed on the surface of the PFR molecule formed a hydrogen bond network with the hydroxymethyl or phenolic hydroxyl group, for example by hydrogen bond interaction, the PFR molecule's dispersion stability was increased. The Tween 60 and PFR composite systems have bigger particle sizes in addition to being more stable. Additionally, the energy barrier of the Tween 60/PFR composite system is determined using the modified DLVO theory for Lewis acid–base hydration, and it is discovered to be consistent with the experimental findings. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. Understanding the co-migration of PFR and surface activity during oil displacement depends heavily on the data. [ABSTRACT FROM AUTHOR]

The anions in the phenol–formaldehyde resin colloid interact with the metal cations in the system to form aggregates with different fractal structures. In this study, Mg2+ and Na+ were studied. At low cationic concentrations, colloid aggregates with the reaction-limited colloidal aggregation (RLCA) mechanism, forming loose aggregates. At high cationic concentrations, colloid aggregates with the diffusion-limited cluster aggregation (DLCA) mechanism, forming dense aggregates. By establishing the triple-layer surface complexation model of phenol–formaldehyde resin, the similarities and differences in interfacial characteristics of phenol–formaldehyde resin under different valence metal cation solutions were explained. The establishment of the triple-layer surface complexation model of phenol–formaldehyde resin is helpful in understanding the change of the aggregation morphology of phenol–formaldehyde resin in the rock gap and groundwater environment, and the change of the colloid interface properties during the co-transport of aggregates and colloidal metal cations. [ABSTRACT FROM AUTHOR]

The macro kinetics of selective hydrogenation of pyrolysis gasoline (PG) over commercial Pd/Al2O3 catalyst is studied in an adiabatic integral fixed-bed reactor. The effects of reaction temperature, pressure and space velocity on the hydrogenation performance are investigated. The power function equation is proposed and successfully fits to the experimental data. The kinetic parameters are estimated by using the fourth-order Runge–Kutta method together with the Levenberg–Marquardt algorithm, which minimized the residual sum of squares between the experimental concentrations and the calculated values. The calculated results of diene value and bromine value are in good agreement with the experimental data in hydrogenation products, indicating that the established kinetic model is appropriate for the first stage hydrogenation of PG. The estimated activation energies of hydrogenation of dienes and monoenes on Pd/Al2O3 catalyst are 29.72 and 41.18 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

In this paper, waste hollow fiber filter membrane is used as a carbon source and KOH as an activator under an atmosphere of protective argon gas to prepare hollow fiber filter membrane-based porous carbon material ZKC-T via a high-temperature pyrolysis activation method. Hollow fiber filter membrane-based porous carbon ZKC-T was found to consist of amorphous carbon, with an irregular three-dimensional network interconnecting pore structure, specific surface area of up to 2934 m2 g−1, and a reasonable pore size distribution. Cyclic voltammetry and constant current charge and discharge tests showed that the hollow fiber filter-based porous carbon material ZKC-700 has excellent electrochemical performance. The carbon material shows a specific capacitance of up to 289 F g−1 at a current density of 1 A g−1 in 6 M KOH electrolyte. In addition, the material shows good cycle stability; after 5000 charge and discharge cycles, the capacitance retention rate is as high as 92.8%. The hollow fiber filter membrane-based porous carbon prepared by this method exhibits excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

Three-dimensional porous graphene/polyaniline (3D-G/PANI) electrode materials were fabricated with hydroquinone-functionalized three-dimensional porous graphene (3D-G) as the substrate. To obtain 3D-G/PANI, the functionalized 3D-G substrate was synthesized through a hydrothermal method first, and then, polyanilines (PANIs) were grown onto the skeleton of functionalized 3D-G substrate by the in situ polymerization of aniline (An). The effect of An amount was optimized to improve the electrochemical performance of 3D-G/PANI. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy and infrared spectroscopy reveal that functionalized 3D-G was successfully prepared and PANIs were uniformly grown on the skeleton of functionalized 3D-G in the form of nanoparticles. The 3D-G/PANI prepared with 80 μL of An exhibits a highest specific capacitance of 542 F/g at 1.5 mA/cm2 (1.14 A/g), 2.05 and 1.54 times those of functionalized 3D-G and PANI, respectively. And the 3D-G/PANI retains a specific capacitance of 435 F/g even at 30 mA/cm2 (22.73 A/g). Moreover, the capacity retention is 82% of initial specific capacitance after 3000 charge/discharge cycles, which is much higher than that of PANI (62%) after 1000 cycles. [ABSTRACT FROM AUTHOR]

Metal–organic framework compounds with abundant network structures are widely used in gas separation and storage, non-linear optics, catalysis, functional materials, and other applications. Here, self-doped nitrogen porous carbon was prepared by a one-step carbonization of Zn2(ATRZ)2SO4·3H2O synthesized using a hydrothermal method. The self-doped nitrogen porous carbon material (ZYC-800) features a three-dimensional network structure, high specific surface area of 725 m2 g−1, and high nitrogen (7.26%) and oxygen (5.46%) contents. Consequently, the ZYC-800 electrode shows a high specific capacitance of 205.5 F g−1 at a current density of 1.0 A g−1 and high capacitance retention rate of 71.1% after 5000 cycles. Moreover, a composite electrode material (ZYC-800-5.3) with small redox additives was prepared and showed a high specific capacitance of 274.1 F g−1 at a current density of 1.0 A g−1. After 5000 cycles, the capacitance retention rate is 72.8%. The results show that the addition of redox additives in self-doped nitrogen porous carbon is an effective method in the development of high performance supercapacitors. [ABSTRACT FROM AUTHOR]

The natural clay have attracted significant interest in microwave absorption (MA) field. In this work, for the first time, a series of modified sepiolite/La-barium ferrite@polyaniline composites (ASEP/BF@PANI) were fabricated by sol–gel self-propagating combustion method and followed by in situ chemical oxidation polymerization and developed into MA materials. The structure, morphology, and magnetic properties of the as-prepared composites were investigated in detail. The electromagnetic parameters of paraffin composites were measured at 2–18 GHz to evaluate their MA properties. After in situ growth of conductive PANI on the ASEP/BF surface, the optimized composites of ASEP/BF@PANI-2 with a filler loading of 60 wt% displays ultra-strong MA properties with the minimum reflection loss (RLmin) of − 71.98 dB (almost 100% absorption) at 10.80 GHz with a thickness of 2.4 mm and the broadest effective absorption bandwidth (EAB, RL below − 10 dB) is as broad as 4.27 GHz (11.41–15.68 GHz) at a thinner thickness of 2.0 mm. More importantly, by adjusting thickness from 1.5 to 2.8 mm, it is also found that the RLmin values are all below − 20 dB (99% absorption) and the qualified EAB ranges from Ku to X bands. Mechanism analysis reveals that the superior MA property of ASEP/BF@PANI-2 composites can be attributed to the improved impedance matching, interference cancellation, and good attenuation ability simultaneously. Therefore, it has great potential to be used as a high-efficiency and tunable MA materials in the future. We think this work could open up a new avenue to promote the electromagnetic applications of low-cost sepiolite-based composites. [ABSTRACT FROM AUTHOR]

The present work aims to combine carbon quantum dots (CQDs) with the good water solubility, biocompatibility, and low toxicity and nano-sized silver sulfide with excellent antibacterial effect in the synthesized composite. The composite was further treated with polyethyleneimine (PEI) and conjugated with graphene oxide (GO). The as-prepared composite Ag2S–CQDs–PEI–GO exhibits a core of Ag2S with the size of 20–50 nm and the shell of CQDs with the average particle size of 1.8 nm. The core shell structure is loaded on the template of PEI–GO. Strong antibacterial effect was observed on Ag2S–CQDs composite against four strands of bacteria Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Enterococcus faecalis (E. faecalis), and Pseudomonas aeruginosa (P. aeruginosa). We briefly discussed the bacteriostatic mechanism of the composite. The as-prepared composite has huge potential in the development of biomedicine. [ABSTRACT FROM AUTHOR]

In this work, La-Ce-doped hexagonal barium ferrite nanoparticles BaLa0.4Ce0.1Fe11.5O19 were prepared by sol–gel self-propagation method. Based on the influence of material structure and impedance matching on microwave absorption properties, bar-shaped attapulgite (ATP) and highly conductive polyaniline (PANI) were introduced, and BaLa0.4Ce0.1Fe11.5O19/attapulgite/polyaniline (BaLa0.4Ce0.1Fe11.5O19/ATP/PANI) ternary composites were prepared by one-step in situ polymerization. The effects of the mass ratio of BaLa0.4Ce0.1Fe11.5O19 and ATP, the content of BaLa0.4Ce0.1Fe11.5O19 and ATP, polymerization time, and polymerization temperature on the microwave absorption properties have been investigated. The phase composition, micromorphology, absorption properties, and microwave absorption mechanism of the materials were analyzed. The results show that the ternary composite has excellent microwave absorption properties and may become one of the most promising absorption materials. After optimization of the preparation process, when the mass ratio of BaLa0.4Ce0.1Fe11.5O19 and ATP is 93:7, the content of BaLa0.4Ce0.1Fe11.5O19 and ATP is 20 wt%, the polymerization time is 8 h, and the polymerization temperature is 0 °C, BaLa0.4Ce0.1Fe11.5O19/attapulgite/polyaniline(BaLa0.4Ce0.1Fe11.5O19/ATP/PANI) ternary composite has unparalleled microwave absorption performance, the minimum reflection loss can reach − 46.40 dB at 16.2 GHz with a thickness of only 1.6 mm, and the absorption bandwidth with reflection loss below − 10 dB is up to 4.1 GHz (13.9–18 GHz). [ABSTRACT FROM AUTHOR]

Pyrolysis gasoline is applied to extract aromatics and to be gasoline blending stock, and its stabilization by catalytic hydrogenation under mild temperature is an important reaction in petrochemical field. Thereinto, styrene hydrogenation was considered as an example for the assessment of the catalysis performance for pyrolysis gasoline hydrogenation. In this work, the adsorption and diffusion of reactants (styrene and H) and the activation energy of styrene hydrogenation on Pd(111), Pd(100), and Pd(110) surfaces are discussed by density functional theory calculations. The adsorption energy of reactants (styrene and H) decreases in the order of Pd(110) > Pd(111) > Pd(100). The activation barriers with feasible intermediate products are investigated and the reaction activity based on the activation barriers follows the order of Pd(111) > Pd(100) > Pd(110). In addition, the diffusion barrier for styrene or H is smaller than the reaction barrier of styrene hydrogenation, indicating the true rate limiting step is the process of hydrogenation rather than the diffusion. Our results provide theoretical guide for the prepared catalyst with feasible surfaces by careful selection of preparation techniques in experiments. [ABSTRACT FROM AUTHOR]

A promising material for supercapacitors based on 4-methylaniline reduced graphene oxide/polyaniline (GP) composite was successfully prepared through a facile one-pot synthesis route. During the preparation process, 4-methylaniline acted as a reducing agent for graphene oxide (GO) as well as a spacer for the resulting reduced graphene oxide (RGO) sheets. The characterization results reveal that GO was successfully reduced by 4-methylaniline and the RGO sheets covered by polyaniline (PANI) nanowires retain favorable dispersibility in the GP composite. The GP composite shows a high specific capacitance (530.4 F g−1 at 0.5 A g−1) with a good cycling stability (87.61% retention after 3000 cycles). Moreover, the GP composite also delivers a good rate performance of 77.5% retention from 0.5 A g−1 to 20 A g−1, but for the graphene oxide/polyaniline (GOP) composite and pure PANI, the retentions are only 47.2% and 28.9%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a promising electrode material for supercapacitor based on P-toluidine-reduced graphene oxide/Mn3O4 (GM) composite was successfully synthesized through a new one-pot synthesis route. To obtain GM composite, graphite oxide (GO) was reduced by P-toluidine first, and then, the resulting reduced graphene oxide (RGO) was hydrothermally treated accompanied with KMnO4 and K2SO4. The effect of K2SO4 on the microstructure and electrochemical performance of as-synthesized composites was investigated. At the weight feed ratio of the theoretical amount of Mn3O4 to GO is 13:1, the GM composite prepared with K2SO4 displays a network structure, but under the same conditions, GM composite prepared without K2SO4 presents a different-sized lumps structure closely piled up by Mn3O4 nanoparticles. A specific capacitance of the GM composite prepared with K2SO4 reaches to 331.6 F/g, almost two times higher than that of the composite prepared without K2SO4. Moreover, the specific capacitance retention of the composite is above 88% after 1000 cycles at 5.0 A/g. [ABSTRACT FROM AUTHOR]

Porous LiMn2O4 spheres was easily fabricated with MnCO3 spheres and MnO2 as precursors and characterized in terms of structure and performance as the cathode of a lithium ion battery. The presence of pores with the average size of about 50 nm throughout the whole LiMn2O4 microspheres was confirmed by scanning electron microscope (SEM) and N2 adsorption-desorption measurements. The electrochemical tests show that the synthesized product has smaller electrochemical polarization, faster Li-ion intercalation kinetics and higher electrochemical stability. It exhibits excellent rate capability and cyclic stability: delivering a reversible discharge capacity of 71 mA h g−1 at a 5 C rate and yielding a capacity retention of over 92% at a rate of 0.5 C after 100 cycles. The superior performance of the synthesized product is attributed to its special structure: porous secondary spheres particles consisting of primary single-crystalline nanoparticles. The nanoparticle reduces the path of Li-ion diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge-discharge and the single crystalline nanoparticle endows the spinel with the best stability. Taking the excellent electrochemical performance and facile synthesis into consideration, the presented porous LiMn2O4 spheres could be a competitive candidate cathode material for high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In the present work, a hybrid Ag@CeO2 nanostructure composite was synthesized via a facile oxidation redox coating approach. The characterization by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy indicates Ag nanoparticles (NPs) are firmly attached to the surface of the CeO2 nanoparticles, driven by the strong interfacial interaction between Ag NPs and CeO2. The antibacterial effects of the Ag@CeO2 hybrid nanocomposite against prokaryotic bacteria were tested using disk diffusion and turbidity method. The plausible mechanism was proposed for the inhibition of bacterial growth. [ABSTRACT FROM AUTHOR]

Supercapacitors are a promising high-power energy storage device due to highly reversible charge-storage process and long cyclic stability. However, the major limitation of supercapacitors lies in their energy density. Here, a high voltage carbon-based supercapacitor is built by using 2 M CH3COONa aqueous solution as electrolyte. In three-electrode system, this paper uses the potentiostatic polarization curves to study the 1.8 V high operating voltage window with the nitrogen-self-doped mesoporous carbon materials (FBNC-700) as electrode materials. In two-electrode system, the FBNC-700 displayed a specific capacitance of 111 F g−1 at a current density of 0.5 A g−1 in 2 M CH3COONa aqueous electrolyte. The 2 M CH3COONa aqueous electrolytes which can improve the energy density to 3.8 times than the 1 M H2SO4 aqueous electrolyte exhibits an excellent performance. Also, following 5000 cycles at a current density of 1 A g−1, the FBNC-700 had good stability with 74.2% capacitance retention. As an aqueous electrolyte, 2 M CH3COONa which has the 1.8 V high operating voltage window can improve the energy density in carbon-based supercapactor. [ABSTRACT FROM AUTHOR]

Oil and gas pipeline networks are a key link in the coordinated development of oil and gas both upstream and downstream. To improve the reliability and safety of the oil and gas pipeline network, inspections are implemented to minimize the risk of leakage, spill and theft, as well as documenting actual incidents. In recent years, unmanned aerial vehicles have been recognized as a promising option for inspection due to their high efficiency. However, the integrated optimization of unmanned aerial vehicle inspection for oil and gas pipeline networks, including physical feasibility, the performance of mission, cooperation, real-time implementation and three-dimensional (3-D) space, is a strategic problem due to its large-scale, complexity as well as the need for efficiency. In this work, a novel mixed-integer nonlinear programming model is proposed that takes into account the constraints of the mission scenario and the safety performance of unmanned aerial vehicles. To minimize the total length of the inspection path, the model is solved by a two-stage solution method. Finally, a virtual pipeline network and a practical pipeline network are set as two examples to demonstrate the performance of the optimization schemes. Moreover, compared with the traditional genetic algorithm and simulated annealing algorithm, the self-adaptive genetic simulated annealing algorithm proposed in this paper provides strong stability. [ABSTRACT FROM AUTHOR]

In this paper, pristine and nitrogen doped ordered porous carbon materials were fabricated by using maltose and amino-maltose synthesized by hydrothermal reaction as precursors via template strategy. The fabricated pristine ordered porous carbon (OPC) and nitrogen doped ordered porous carbon (NOPC) exhibit excellent textural properties and good capacitance performance, which specific surface area ( S) reach 1107 and 726 m g for the pristine OPC and NOPC materials while the specific capacitance reach up to 139 and 183 F g under a current density of 0.5 A g, respectively. The capacitance retention rate for the pristine OPC and NOPC reaches ca. 81 and 92% as the current density increased from 0.5 to 20 A g, and no apparent capacitance decrease was observed after 5000 cycles. Although a sharp decrease of specific surface area was observed after N doping, the specific capacitance of NOPC was improved about 31% than that of the pristine OPC, the enhanced wettability and surface availability after N doping were found to be responsible for the enhanced capacitance performance of NOPC. [ABSTRACT FROM AUTHOR]

Nano-sized LiMnO materials are synthesized via a simple one-step solid-state reaction using lithium acetate and lithium oxalate as lithium sources, respectively. The physical and electrochemical properties of LiMnO materials are investigated by X-ray diffraction, scanning electron microscopy and electrochemical measurements. The results show that both of the as-prepared materials are pure nano-sized LiMnO with narrow particle size distribution. Compared with lithium oxalate, lithium acetate is propitious to improve the crystallinity and size distribution of nano-sized LiMnO. Besides, LiMnO synthesized from lithium acetate shows low resistance, good ability to inhibit Mn dissolution, long cycle life and excellent rate property. Finally, the adverse effect of nano-sized LiMnO, which has increased contact area between acid-containing electrolyte and LiMnO cathode electrode to aggravate dissolution and corrosion behavior, is treated by LiCO additive in electrolyte. Results show that electrochemical performance of nano-sized LiMnO is improved, due to the fact that LiCO additive can not only consume HF and other Lewis acid in the commonly used LiPF-based electrolyte, but also decrease interfacial impedance to promote the migration of Li ions through cathode surface film. [ABSTRACT FROM AUTHOR]

Lithium bis(oxalate)borate (LiBOB) is a promising salt for lithium-ion batteries. However, it is necessary to exert the electrochemical performance of LiBOB by the appropriate solvent. With dimethyl sulfite (DMS) as mixed solvents, the electrochemical behavior of γ-butyrolactone (GBL) with LiBOB is studied in this paper. It shows that LiBOB-GBL/DMS electrolyte has high oxidation potential (>5.3 V) and satisfactory conductivities. When used in lithium and mesophase carbon microbead cells, the novel electrolyte exhibits not only excellent film-forming characteristics but also low impedances of the interface films. Besides, when used in LiFeO/Li cells, compared to the cell with the electrolyte system of 1 mol L LiPF-ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v/v), LiBOB-based electrolyte exhibits several advantages, such as more stable cycle performance at room temperature and higher mean voltage. [ABSTRACT FROM AUTHOR]

Mesoporous carbons (NZMC) were synthesized by using single-step nanocasting in which maltose was used as carbon precursors and natural zeolite as template. Physical property characterization methods such as field emission scanning electron microscopy, transmission electron microscopy, N absorption/desorption, and X-ray diffraction were employed to determine the structure and crystallinity of NZMC. The results show that the materials possess a disordered lamellar structure and numerous nanopores. The specific surface area and pore volume reach up to 1076.9 m/g and 1.46 cm/g, respectively. Typical electrochemical measurements such as constant current charge/discharge test, cyclic voltammetry (CV), and electrochemical impedance spectra revealed that NZMC has excellent charge storage capability. Specific capacitance is 176 F/g in the alkaline media when the current density is 600 mA/g. The CV curve maintains a typical CV quasi-rectangular feature at a scan rate of 5-100 mV/s, which indicates that the materials perform well rate capability. The combination resistance of the carbon materials is 0.78 Ω. After 750 cycles, the specific capacitance retention value is 94.5 %, which proves that NZMC is a promising electrode material for electrochemical capacitors because of its long-term cycle stability. [ABSTRACT FROM AUTHOR]

Microsilica, one kind of industrial solid waste material, was utilized firstly to prepare a carbon-microsilica composite adsorbent (CMS). The prepared adsorbent was characterized with XPS, SEM and Gas sorption experiments. The results indicated the SOH groups, which are very effective in capturing cationic organic dye, were introduced onto the surface of CMS; the Brunauer-Emmett-Teller (BET) surface area (S) and total pore volume (V) of CMS reach 51m/g and 0.045 cm/g, respectively. Meanwhile, the possibility of the utilization of the adsorbent for removal of methylene blue (MB) from aqueous solution was investigated. The effect of pH, contact time and initial MB concentration for MB removal were studied. Equilibrium data were modeled using the Langmuir, Freundlich and Dubinin-Radushkevich equations to describe the equilibrium isotherms. It was found that data fit to the Langmuir equation better than the Freundlich equation. Maximum monolayer adsorption capacity was calculated at different temperatures (298, 308, and 318 K) reach 251.81, 283.76 and 309.70 mg/g, respectively. It was observed that adsorption kinetics obeys the pseudo-first-order equation. [ABSTRACT FROM AUTHOR]

The growing significance of biodegradable plastics for environmental protection underscores the need to enhance their performance of degradation in natural environments. This study prepared PLA/PVA blends with varying ratios to assess the impact of PVA on their thermal properties, mechanical properties, and degradation behavior. Results indicated that as the PVA content increased from 0 to 100%, both tensile and flexural strengths initially decreased before increasing. Furthermore, the decomposition temperature of the blends decreased by 18–35 °C as the PVA content increased. Specifically, pure PLA exhibited a thermal degradation temperature of 332 °C; while, the blend with 80% PVA showed a reduced temperature of 296 °C. Hydrolysis tests showed that weight loss increased significantly with higher PVA content, with the 20PLA/80PVA blend losing 78.9% of its weight after 30 days, compared to only 0.13% for pure PLA. The mechanical properties of the 20PLA/80PVA blend decreased by 98.31% in tensile strength and 79.19% in hardness after 30 days of hydrolysis, demonstrating accelerated degradation. Soil degradation tests further revealed that the 20PLA/80PVA blend lost over 85% of its weight within 20 days; while, pure PLA lost less than 1%. These results suggest that altering the PLA/PVA ratio can substantially enhance degradation rates, offering valuable insights for the development of efficient biodegradable plastics. [ABSTRACT FROM AUTHOR]

The electrochemical performance of supercapacitors with mesoporous carbon FBNC-700 as electrode material and sodium citrate solution as electrolyte was investigated using a two-electrode system. The results revealed a specific capacitance of mesoporous carbon FBNC-700 of 112.4 F g−1 at current density of 0.5 A g−1 in 0.75 M sodium citrate electrolyte in the voltage window from −1.0 to 0 V. The maximum stable voltage window of sodium citrate electrolyte reached 2.1 V (−1.3 to 0.8 V), and mesoporous carbon FBNC-700 exhibited high cycle stability (14.53% loss over 5000 cycles at 2 A g−1 current density). In addition, the energy density of the capacitor reached 87.79 Wh kg−1 at the maximum voltage window, being significantly higher than that obtained using H2SO4 or KOH electrolyte. [ABSTRACT FROM AUTHOR]