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The diluent NaCl was introduced into the WO 3 -Mg-C-Na 2 CO 3 system to prepare submicron tungsten carbide (WC) powders via salt-assisted combustion synthesis. The products were analyzed by SEM, EDS and XRD, and the effects of C content on morphology, average particle size and phase composition of the products were studied. Results show that on basis of the m = 0.125 (the number of moles of Na 2 CO 3 ), when the number of moles of carbon in raw material increases from l =2 to 2.25 and 2.5, before leaching, the product is made up of a small number of large size particles and a large number of small size particles; after leaching, samples are composed of aggregates of submicron particles, and the sintering phenomenon between particles is very weak, indicating low degree of aggregation. Particle size distribution of leached product almost falls into the normal distribution, and the particle sizes range from 200 nm to 350 nm. Under the condition of l =2.25, a main target product is WC, and the content of by-products W 2 C is extremely few. That is, k = 2.0 (the number of moles of NaCl), m = 0.125, and l =2.25 are the process conditions for single-phase WC synthesis. [ABSTRACT FROM AUTHOR]

It is currently not understood how some chronic infections exhaust antigen-specific T cells over time and which pathogen components contribute to exhaustion. Here, we dissected the behavior of primed CD4+ T cells exposed to persistent antigen using an inducible transgenic mouse system that allowed us to control antigen presentation as the only experimental variable, independent of the persistent inflammation and disease progression that complicate infectious models. Moreover, this system restricted antigen presentation to dendritic cells (DC5) and avoided confounding B, CD8+ T, or innate cell responses. When antigen presentation was extended beyond the expansion phase, primed CD4+ls survived, but exhibited reduced memory functionality in terms of their proliferative capacity and cytokine expression potential., The effect was antigen dose and time dependent, not associated with increased PD-1 expression or reduced calcium influx, but impaired Jun phosphorylation in response to ICR engagement. Upon antigen removal, the cells regained the ability to proliferate, but remained unable to produce high levels of IL-2 and TNF-α. These data show that persistent antigen by itself rapidly induces a dysfunctional state in CD4+ T cells that is only partially reversible upon antigen removal. These findings have implications for vaccine optimization and for the possible reinvigoration of CD4+ T cells during chronic infection. [ABSTRACT FROM AUTHOR]

A Nile red (NR) dye cathode with an asymmetric redox structure of para C＝N and C＝O bonds was developed for use in an efficient lithium organic battery with a good capacity of 125 mA h g−1 and two visible discharge/charge voltage plateaus (≈2.0 V and ≈1.7 V). The NR cathode demonstrated the advantages of employing cost-effective dyes to achieve multigradient voltage platform regulation. [ABSTRACT FROM AUTHOR]

The strong metal-support interaction and its chemical nature was examined over a Ir/TiO2 catalyst, constructed by dispersing 2 nm Ir colloids on the {001} facets of anatase TiO2. Air-calcination of the Ir/TiO2 sample led to the oxidation of Ir particles into IrOx clusters. Upon H2-reduction at 573 K, the IrOx species were reduced into metallic with a prominent character for H2-chemisrption. As further raising the temperature to 673–773 K for H2-reduction, strong metal-support interactions occurred pronouncedly and the amounts of chemically adsorbed hydrogen dropped significantly. Spectroscopic and microscopic analysis found that the formation of surface Ir-Ti alloys on the Ir particles dominated the metal-support interactions, rather than the traditional encapsulation of the metal particles by TiOx overlayers. The surface Ir-Ti alloy, thus formed, promoted the selectivity for hydrogenating the C = O bond in acetophenone by altering the adsorption model of the C = O bond in the substrate. [ABSTRACT FROM AUTHOR]

The catalytic performance is tunable by controlling the reconstruction process in operando conditions. The surficial and interfacial properties of catalysts determine the catalytic activity of materials. • We tuned the catalytic performance of NiAu-based materials by the heat triggered the surficial and interfacial modification. • We promoted the activity stability of catalysts for hydrogen generation by controlled the reconstruction during reaction. • We used XPS and DFT to verify the synergistic effect between Au and Ni/NiO, in which they show high similarity. Catalytic activity of nanostructured materials are closely tied with structure, thus developing nanomaterials with processable structures has arisen as a new strategy for designing high active catalysts. In this work we report the realization of controllable structural evolution of NiAu-based materials in operando conditions. The structure evolution of NiAu catalysts at atomic scale has been characterized by ex-situ scanning transmission electron microscopy. The catalytic activity for ammonia borane hydrolysis has promoted for 4.4-fold after adapting structural evolution. The catalytic stability has increased for 16-fold of maintaining 75% activity. This work provides inspiration for emerging catalysts design based on bimetallic nanoparticles with both high performance and durability in a catalytic reaction system. [ABSTRACT FROM AUTHOR]

Wearable electronic devices have emerged as a pivotal technology in healthcare and artificial intelligence robots. Among the materials that are employed in wearable electronic devices, organic thermoelectric materials possess great application potential due to their advantages such as flexibility, easy processing ability, no working noise, being self-powered, applicable in a wide range of scenarios, etc. However, compared with classic conductive materials and inorganic thermoelectric materials, the research on organic thermoelectric materials is still insufficient. In order to improve our understanding of the potential of organic thermoelectric materials in wearable electronic devices, this paper reviews the types of organic thermoelectric materials and composites, their assembly strategies, and their potential applications in wearable electronic devices. This review aims to guide new researchers and offer strategic insights into wearable electronic device development. [ABSTRACT FROM AUTHOR]

Hybrid nanostructures with a plasmonic core and catalytic shell often show significantly enhanced catalytic efficiency under illumination of specific frequency. Excitation of localized surface plasmonic resonance on plasmonic metals under illumination can generate hot electrons that assist in the catalytic reaction. However, the correlation between the microstructural geometry, dielectric environment, internal energy flow in the hybrid structure, and the chemical reaction rate is so far not clear. Here, a composite with a plasmonic Au metal yolk and a nearly transparent Ni3S2 shell is designed to maximize the absorption of incident light by forming strong localized surface plasmonic resonance at the yolk as predicted by 3D finite element method. The incoming photoenergy is dominantly dissipated on the shell by forming electron–hole pairs, leading to higher energy flow rate for oxygen evolution reaction. The overpotential is 252 mV at 10 mA cm−2 and the catalytic activity of Au@Ni3S2 achieves ca. 85‐fold that of pure Ni3S2 under illumination and surpasses the commercial IrO2 catalyst. The study opens the door of exploration of highly effective hybrid composite catalysts for energy applications. Composite materials with a plasmonic Au metal yolk and a Ni3S2 shell maximize the absorption of incident light by forming strong localized surface plasmonic resonance at the yolk. The incoming photoenergy is dominantly dissipated on the shell by forming electron–hole pairs, leading to higher energy flow rate for oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Conversion of CO2 gas to CO fuels is one of the most promising solutions for the increasing threat of global warming and energy crisis. The efficient catalyst Ni–Au dumbbell converting CO2 into CO at elevated temperatures has high CO product selectivity; however, the accompanied atomic diffusion and subsequent surface reconstruction affect the catalytic efficiency of chemical reaction. Atomic scale characterization of structural evolution of the catalyst, which is essential to correlate the functional mechanism to active catalyst surfaces, is yet to be studied. Here, in situ transmission electron microscopy experiments and atomistic simulations are performed to characterize the structural evolution of Ni–Au dumbbell nanoparticles under two different external stimuli. In the condition of high temperature and vacuum, the Ni–Au nanostructure reveals a clear shape reconstruction from the initial dumbbell to core–shell‐like, which is induced by capillary force to minimize free surface energy of the system. The shape transformation involves two stages of processes, initial fast Au diffusion followed by slow source‐controlled diffusion. At ambient temperature, the combination of CO2 and electron flux surprisingly induces analogous structural transformation of Ni–Au nanostructure, where the associated chemical reaction and CO absorption stimulate the Au migration on Ni surface. Such surface reconstruction can be widely present in catalytic reactions in different environmental conditions, and the results herein demonstrate the detailed processes of Ni–Au structure evolution, which provide important insights for understanding the catalyst performance. At high temperature or gas environment, the Ni‐Au nanostructure reconstructs from dumbell to core‐shell. Such surface reconstruction is widely present in catalytic applications, and the dynamical structural evolution provides important insights for understanding catalyst performance. [ABSTRACT FROM AUTHOR]

Perylene dianhydride (PDA), a low-cost, readily available, and chemically stable organic cathode material, has received extensive attention in recent years. However, its large π planar structure often results in poor or difficult-to-control micro-nanostructures during conventional electrode processing methods, such as dry mixing. This leads to limited cycling life and rate performance. Here, we present a simple electrospinning strategy for controlling the micro-nanostructures of electrodes based on PDA, carbon black Super P (SP), and polyvinylidene fluoride (PVDF) composites. The spinnable PVDF polymer not only provides the micro-nanofibrous structure but also realizes the function of the binder in the electrodes, offering the hierarchical micro-nanostructures of the electrospun PDA (PDA-es) electrodes. The unique structure enables PDA-es electrodes to possess rapid charge transport properties and ultrafast reaction kinetics. Specifically, the PDA electrode based on high molecular weight electrospun PVDF (PDA-es-H) demonstrates a high initial specific capacity (126.2 mA h g−1), robust cycling stability (∼95% and ∼60% capacity retention after 100 cycles at 50 mA h g−1 and 1000 cycles at 100 mA h g−1, respectively), and excellent rate performance. This study provides a straightforward and efficient strategy for realizing the micro-nanostructures of organic electrodes for high-performance lithium-organic batteries. [ABSTRACT FROM AUTHOR]

An in situ gel separator based on an electrospun three-layer nanofibrous membrane (PSE11-Gel) is developed for high-performance lithium-organic batteries (LOBs). The highly efficient shuttle effect inhibition of organic cathode molecules or lithiated intermediates has been demonstrated for PSE11-Gel to realize high-capacity stable LOBs. [ABSTRACT FROM AUTHOR]

Dual-layer and tri-layer broadband antireflective (AR) films with excellent transmittance were successfully fabricated using base-/acid-catalyzed mixed sols and propylene oxide (PO) modified silica sols. The sols and films were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), transmission electron microscope (TEM), and scanning transmission electron microscope (STEM). FTIR and TEM results suggest that the PO molecules were covalently bonded to the silica particles and the bridge structure existing in PO modified silica sol is responsible for the low density of the top layer. The density ratio between different layers was measured by cross-sectional STEM, and the results are 1.69:1 and 2.1:1.7:1 from bottom-layer to top-layer for dual-layer and tri-layer films, respectively. The dual-layer film demonstrates good stability with 99.8% at the central wavelength of 351 nm and nearly 99.5% at the central wavelength of 1053 nm in laser system, and for the tri-layer AR film, the maximum transmittance reached nearly 100% at both the central wavelengths of 527 and 1053 nm. [ABSTRACT FROM AUTHOR]

Terahertz (THz) technologies provide opportunities ranging from calibration targets for satellites and telescopes to communication devices and biomedical imaging systems. A main component will be broadband THz absorbers with switchability. However, optically switchable materials in THz are scarce and their modulation is mostly available at narrow bandwidths. Realizing materials with large and broadband modulation in absorption or transmission forms a critical challenge. This study demonstrates that conducting polymer‐cellulose aerogels can provide modulation of broadband THz light with large modulation range from ≈ 13% to 91% absolute transmission, while maintaining specular reflection loss < −30 dB. The exceptional THz modulation is associated with the anomalous optical conductivity peak of conducting polymers, which enhances the absorption in its oxidized state. The study also demonstrates the possibility to reduce the surface hydrophilicity by simple chemical modifications, and shows that broadband absorption of the aerogels at optical frequencies enables de‐frosting by solar‐induced heating. These low‐cost, aqueous solution‐processable, sustainable, and bio‐friendly aerogels may find use in next‐generation intelligent THz devices. [ABSTRACT FROM AUTHOR]

Abstract Surface modification of nanostructured catalysts is fundamental in accelerating sluggish oxygen evolution reaction (OER). Herein we demonstrate that nanostructured Nickel Selenide (NiSe2) exhibits excellent capability for OER owing to the high compatibility between (200) plane and alkaline solution. The dendrite-like nickel selenide achieves a specific current density of 10 mA/cm2 at an overpotential low to ∼299 mV. The NiSe2 has high stability, in which overpotential decreased ∼2 mV after 10 000 cycles. We demonstrated that the catalytic efficiency of OER could be promoted by increasing the exposure ratio of (200) plane. This work discloses that kinetics of OER are related to specific facets exposure, in which it opens up the possibility of designing active and stable catalysts for OER utilization. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

This study investigated the effects of free-range (FR) and cage-rearing (CR) systems on intestinal health, carcass traits, and microbial diversity in the Danzhou chicken breed. Two groups of 125 hens in each group, aged 42 wk, were reared under FR and CR systems. At 50 wk, 50 hens from each group were randomly selected for carcass analysis and 10 hens for intestinal morphology and microbiota profiling. Results indicated a significant increase in villus height (VH) in the duodenum (P < 0.05) , jejunum (P < 0.01), and ileum (P < 0.001) of the CR group. Additionally, the ratio of VH to crypt depth (VR) significantly (P < 0.001) increased in the jejunum, while crypt depth (CD) decreased significantly (P < 0.001) in the same section in the CR group. Carcass traits, including dress weight (DW), eviscerated with giblet weight (EGW), eviscerated weight (EW), and leg muscle weight (LW) significantly improved (P < 0.05) in the CR group. Microbial diversity showed significant β-diversity differences, with Lactobacillus, Enterococcus , and Oxalobacteraceae as dominant biomarkers in the CR group. Conversely, Actinomycetaceae, Erysipelotrichaceae, Coriobacteriaceae, Eubacterium, Actinomyces, Scardovia, and Lachnospiraceae were dominant in the FG group. Correlation analysis showed duodenum Lactobacillus was positively correlated with VH (P < 0.05) , EW (P < 0.05), and LW (P < 0.001). Jejunum Lactobacillus was positively correlated considerably with VH (P < 0.01), VR (P < 0.05) , DW (P < 0.05), EGW (P < 0.01), and LW (P < 0.001). Ileum Lactobacillus was positively correlated with EGW (P < 0.01), EW (P < 0.05), and LW (P < 0.01). Aeriscardovia in duodenum was positively (P < 0.01) associated with EGW. Enterococcus in the duodenum was positively (P < 0.05) associated with EGW and in Jejunum positively correlated with VH (P < 0.05) and VR (P < 0.01). The study concludes that cage rearing improves intestinal health, carcass traits, and microbial diversity in Danzhou chickens, with Lactobacillus and Enterococcus playing key roles. [ABSTRACT FROM AUTHOR]

Because of the booming industry, the leaked oily wastewater has seriously threatened human health and the ecological environment. To address this issue, we herein report a composite membrane for oil–water separation. Firstly, a silicone semi-interpenetrated network (IPN) was synthesized by the in situ polymerization of aminopropyl trimethoxysilane and vinyl trimethoxysilane in a polylactic acid (PLA) solution. Then, the PLA@silicone semi-IPN fibrous membranes were obtained via electrospinning the synthesized solution. The silicone semi-IPN offers adjustable inner morphologies and a good porous structure for fibrous membranes. Specifically, the PLA@silicone semi-IPN fibrous membrane shows an outstanding oil-absorbing value of 83.9 g/g and a good lipophilic/hydrophobic performance with a contact angle of 158.7°. More importantly, the obtained fibrous membrane owned a good oil–water selectivity. The oil droplets could be spread and absorbed by the fibrous membrane in water within 2.2 s. Such efficient separation for oil and water mixtures will make the PLA@silicone semi-IPN fibrous membrane a good candidate for oil-polluted water treatments. [ABSTRACT FROM AUTHOR]

• ZnO-Al 2 O 3 layer has a mesoporous structure and good affinity to H 2 S gas. • ZnO in layer can selectively adsorb and react with H 2 S gas molecules to form ZnS. • The formation of ZnS increases layer's elastic modulus and the sensing performance. • The SAW sensor can detect 10 ppb H 2 S gas with a response of 500 Hz. ZnO-Al 2 O 3 nanocomposite was synthesized and developed as a high performance sensitive and selective layer for surface acoustic wave (SAW) sensor, aiming for in-situ detection of H 2 S gas in ppb level operated at room temperature. ZnO-Al 2 O 3 nanocomposite, synthesized though a sol-gel method, was spin-coated onto a quartz based SAW resonator. This composite layer inherits the mesoporous structure of the Al 2 O 3 layer and good affinity to H 2 S gas molecules of the ZnO layer, and thus can selectively adsorb and react with H 2 S gas molecules to form ZnS compounds on its surface. This reaction leads to significant decreases of both pore sizes and total pore volume of the layer, an increase of layer's elastic modulus, thus causing a large positive shift of the frequency responses of the SAW sensor. The sensor operated at room temperature shows a frequency response of ∼500 Hz to 10 ppb H 2 S, with an excellent selectivity and good recovery property. [ABSTRACT FROM AUTHOR]

• The surfactant- and polymer-free synthesis of a new kind of nonmetallic N-doped Pt nanoparticles. • The N doping within Pt lattice induces tensile strain, leading to an enhanced ORR activity and excellent durability. • This N-doped Pt nanocatalyst shows a negligible degradation in ORR activity (only 3.7%) after a 20,000-cycle ADT. • Provide a competitive strategy for preparation of Pt-based oxygen reduction catalysts in PEMFCs. The availability of highly active and durable Pt based catalysts at a high metal loading is a prerequisite for practical applications in proton exchange membrane fuel cells (PEMFCs). Herein, we for the first time report the simple surfactant- and polymer-free synthesis of nonmetallic N doped Pt nanoparticles as electrocatalysts with an enhanced activity and excellent durability for oxygen reduction reaction (ORR) and such a synthetic procedure has been extended in a large-scale (>100 g/batch) for practical production already. X-ray diffraction and aberration-corrected transmission electron microscopy results clearly confirm that the doping of N within Pt lattice leads to the tensile strain in Pt nanoparticles. The tensile-strained Pt nanoparticles exhibit a negligible ORR activity decay by only 3.7% after a 20,000-cycle accelerated durability test (ADT) between 0.6 and 1.1 V/RHE, which places it among the most durable Pt-based catalysts reported for the ORR. While eliminating the strain effect, the activity degradation of the ORR on the Pt nanoparticles increases to 18.1%, close to that of commercial Pt/C catalyst (27.9%). Importantly, the tensile strain of N doped Pt nanoparticles is still remained after the ADT, assessing the structural stability of N-doped Pt nanoparticles. Theoretical calculations reveal that the N-doped Pt nanoparticles are chemically more stable than pristine ones due to Pt-N bonding effect, thus explaining well its excellent durability during the ORR. PEMFC integrated with as-prepared catalyst delivers a cell voltage of 0.65 V at the current density of 1.4 A·cm−2, satisfying the needs for vehicle use. The simple surfactant- and polymer-free approach presented here can be readily applied to other nonmetal doped Pt nanostructures and provides a promising potential for the practical applications in PEMFCs. [ABSTRACT FROM AUTHOR]

CuCo 2 S 4 is regarded as a promising electrode material for supercapacitor, but has inferior conductivity and poor cyclic stability which restrict its wide-range applications. In this work, hierarchically hybrid composite of CuCo 2 S 4 /carbon nanotubes (CNTs) was synthesized using a facile hydrothermal and sulfuration process. The embedded CNTs in the CuCo 2 S 4 matrix provided numerous effective paths for electron transfer and ion diffusion, and thus promoted the faradaic reactions of the CuCo 2 S 4 electrode in the energy storage processes. The CuCo 2 S 4 /CNTs-3.2% electrode exhibited a significantly increased specific capacitance of 557.5 F g−1 compared with those of the pristine CuCo 2 S 4 electrode (373.4 F g−1) and CuO/Co 3 O 4 /CNTs-3.2% electrode (356.5 F g−1) at a current density of 1 A g−1. An asymmetric supercapacitor (ASC) was assembled using the CuCo 2 S 4 /CNTs-3.2% as the positive electrode and the active carbon as the negative electrode, which exhibited an energy density of 23.2 Wh kg−1 at a power density of 402.7 W kg−1. Moreover, the residual specific capacitance of this ASC device retained 85.7% of its original value after tested for 10,000 cycles, indicating its excellent cycle stability. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ar ion implantation modifies the surface of fused silica and improves the LIDTs of the optics at moderate fluences. • The generation of compressive stress layer strengthens the surface of fused silica by surface densification. • The surface molecular structure of fused silica changes during the Ar ion implantation process. • The concentration of defects at fused silica surface reduces when the ion fluence is below 1 × 1017 ions/cm2. Abstract In this work, effects of 10 keV argon ion implantation on laser-induced damage threshold (LIDT) of fused silica were systematically investigated with ion fluences ranged from 1 × 1016 ions/cm2 to 1 × 1018 ions/cm2. Results show that only when the ion fluence increases above 1 × 1017 ions/cm2, the surface roughness apparently increases due to the formation of argon bubbles in the surface of fused silica. The concentration of defects decreases with the increased fluences up to 1 × 1017 ions/cm2 but then increases further, especially for the oxygen deficient center (ODC) defect. Based on the nanoindentation test results, Ar ion implantation generates large compressive stress and strengthens the surface of fused silica by surface densification. With the increase of the Ar ion fluences, the LIDTs of the samples increase due to the increases in both surface compressive stress and defects annihilation. However, at higher ion fluences, the increase of the densities of defects and argon bubbles are identified as the key reasons for the decrease of the LIDTs. Therefore, Ar ion implantation can improve the LIDTs of fused silica at moderate fluences. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pt 3 Fe particle is individually confined by SiO 2 forming the Pt 3 Fe@SiO 2 core–shell nanostructure. • The crystal-phase of a single Pt 3 Fe particle is tuned from the disordered A1 to the ordered L1 2. • L1 2 phase exhibits the superior behaviors than A1 phase for C 2 H 2 hydrogenation toward C 2 H 4. • Pt 3 ensemble with isolated 3-fold hollow site is enriched on L1 2 particle. Tuning the crystal-phase of bimetallic particles enables a precise control of catalytically active sites but is experimentally challenged by the averaging ensemble effects that are caused by the particle communications occurred during the crystal-phase transformation. Here, H 2 -treatment at 773–973 K of Pt 3 Fe single-nanoparticle, confined by a permeable silica shell, achieved crystal-phase transformation from the disordered A1 phase to the chemically ordered L1 2 phase. Detailed microscopic and spectroscopic characterizations have identified that the disordered A1 particle possessed contiguously connected large Pt domains while the ordered L1 2 particle afforded regularly populated Pt 3 ensembles surrounded by Fe single-atoms. The isolated 3-fold hollow Pt site in the three-atom ensemble efficiently boosted the adsorption of acetylene, yielding a much higher hydrogenation activity. The reaction rate of the L1 2 particle was twice of that for the A1 particle. Moreover, the charge transfer from the neighboring Fe single-atoms to the Pt atoms on the L1 2 particle expedited the desorption of ethylene, promoting the selectivity as well. Overall, both geometric and electronic interactions in the ordered crystal-phase synergistically facilitated the selective hydrogenation of acetylene to ethylene. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel polyimide-based nanofiltration membranes were prepared by constructing dual coordination interactions. • The skin and supporting layers of NF membranes can be controlled by designing coordination interactions. • Nanofiltration membrane performance optimized by controllable microstructure. Polyimide-based nanofiltration membranes (NF) featuring customizable chemical structure and outstanding comprehensive performance have garnered tremendous interest for potential applications in ions rejection. Coordinated interactions can build supramolecular networks in polyimide that reshuffle phase separation behavior during membrane formation, thus conferring microstructural flexibility to nanofiltration membranes. In this paper, novel nanofiltration membranes were prepared by constructing dual coordination interactions in polyimide, and the structures were confirmed by NMR, FTIR, EDX, and XPS analyses. As expected, the skin and supporting layers of the PI-based NF membranes can be controlled by designing coordination conditions during membrane formation. A promising result is that the resulted NF membranes occur higher reject of metal ions than the pristine membranes prepared by conventional non-solvent induced phase separation methods. The optimized performance showed significantly higher permeability for removing Mg2+ ions, giving water permeance of 477.7 L m−2 h−1·bar−1 and a rejection of over 80%. Moreover, the resulted PI-based NF membranes occur better solvent resistance than the pristine NF membranes due to the enhanced coordination structures. As a preliminary study, this work gives a new strategy to regulate the microstructure of nanofiltration membranes, promising further potential for applications in ion removal. [ABSTRACT FROM AUTHOR]

Multi-fracture hydraulic fracturing has been widely used in unconventional oil or gas production. Determining the fracture geometry at the end of multi-fracture propagating simultaneously and early estimating of the stimulation performance can improve the understanding of the well productivity. Coupled with other information on treatment execution, this understanding may help define changes in treatment design and execution that increase well productivity. G-function pressure drop curves analysis is an important method to determine the single fracture geometry. However, it is difficult to estimate the multi-fracture geometry in each fracturing stage by G-function model. In this paper, we propose a new model to calculate the multi-fracture geometry based on the G-function plot of pressure falloff data after hydraulic-fracture treatment in each fracturing stage. First, stress shadow and the dynamic partitioning of flow rate are first considered in the G-function model for the calculation of multi-fracture geometry distribution. Second, proportional function of fracture length is incorporated in the G-function model in this paper, which solves the problem of the non-uniqueness of fracture lengths and widths calculation outcomes. Through comparing with the numerical simulation results, our model is verified. Finally, a sensitivity analysis of the fracture control parameters is performed based on our model. This paper provides a new semi-analytical method to quickly determine the multi-fracture geometry after each horizontal well fracturing stage. It can be used to evaluate the performance of multi-fracture hydraulic fracturing and help improve the well productivity. • A field-scale model was proposed to determine multi-fracture geometry by hydraulic-fracture treatment pressure falloff data. • Stress shadow and partitioning of flow rate were considered in the G-function model for calculating multi-fracture geometry. • Effects of physical parameters (N , σ min , n ′ , d , and H) related to multi-fracture characteristics were analyzed. [ABSTRACT FROM AUTHOR]

Developing fully rigid-chain polyimides with reversible sol-gel/gel-sol transitions is of great interest for designing high-performance materials. To date, few approaches have been employed to construct polyimide gels other than hydrogen bonding. Here, we report a polyimide-Zn(II) complex with thermo-responsive sol-gel/gel-sol transition behavior by introducing supramolecular coordination interactions. The tunable dynamic sol-gel behaviors of polyimide-Zn(II) complexes were confirmed using rheological methods. Microstructure analysis shows that coordination interactions occur between the benzimidazole molecules and Zn(II) ions. As a result, the apparent viscosity of the polyimide-Zn(II) complex even rises approximately four orders of magnitude higher than that of the PI-neat oligomer solution. Based on the 2D-correlation spectra and X-ray diffraction results, we deduced that the formation of dense chain stacking caused by coordination effects plays an essential part in the reversible sol-gel transition. As a preliminary experiment, this work gives a novel strategy to construct polyimide gels, showing application prospects in the fabrication of porous polyimide membranes, high-performance polyimide fibers, and aerogels, etc. • A novel polyimide-Zn(II) organogel was prepared by introducing supramolecular coordination bonds. • Strong interactions undergo between the benzimidazole molecules and Zn(II) ions. • The chain stacking behavior caused by coordination effects plays an essential part in the reversible sol-gel transition. [ABSTRACT FROM AUTHOR]

Photocatalytic overall water and CO2 conversion splitting under visible light irradiation. • Synthesis of phosphorus doped g-C3N4 (P-CN) with its coupling to CdSe quantum dots (QDs). • For band gap engineering conformation DFT and Time depended-DFT were used. • Expending visible-light response of g-C3N4 upto near infra-red region (700 nm). • Photocatalytic Activities for solar fuel production and environmental remediation. Solar energy harvesting and conversion into useful chemical energy with the aid of semiconductor photocatalysts is a promising technique to solve both energy and environmental issues. This work reports a successful synthesis of CdSe quantum dots (QDs) modified phosphorus doped g-C 3 N 4 (P-CN) for advanced photocatalytic applications. Phosphorus doping and structural coupling with CdSe QDs are shown to significantly extend visible-light response of g-C 3 N 4 up to 700 nm. The optimized sample 4CdSe/P-CN demonstrates enhanced visible-light driven overall water splitting activities for H 2 and O 2 evolution i.e. 113 and 55.5 μmol.h−1. g−1, respectively, as well as very high photocatalytic CO 2 to CH 4 conversion efficiency (47 μmol.h−1. g−1). It also exhibit higher activity (78 %) for 2,4-dichlorophenol degradation as compared to pristine CN-sample. Combined photoluminescence, transient/single wavelength photocurrent, photoelectrochemical, and coumarin fluorescence spectroscopy demonstrate that 4CdSe/P-CN nanocomposite exhibit enhanced charge separation efficiency which is responsible for improved visible light catalytic activities. Our work thus provide a new strategy to design low-cost and sustainable photocatalysis with wide visible-light activity for practical overall water splitting and CO 2 reduction applications. [ABSTRACT FROM AUTHOR]