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Hierarchically superhydrophilic poly(vinylidene fluoride) membrane with self-cleaning fabricated by surface mineralization for stable separation of oily wastewater
No full textLong-term separation of highly emulsified oily wastewater is still challenging in advanced membrane technologies. Herein, 8-FeOOH nanorods were in-situ inlaid on a hierarchically superhydrophilic poly(vinylidene fluoride) (PVDF) ultrafiltration membrane surface via a facile biomimetic mineralization process. The 8-FeOOHdecorated hierarchical PVDF membrane surface with the organic-inorganic hybrids showed excellent hydrophilicity and ultralow underwater oil adhesion force. After in-situ anchoring of 8-FeOOH nanorods, the polydopamine/polyethylenimine (PDA/PEI) modified hierarchical PVDF membrane showed improved permeation flux behaviors, higher oil removal, demulsification, and better anti-oil-fouling properties during 1440-min continuous separation of stabilized soybean oil-in-water (o/w) and crude o/w emulsions. In contrast, the unmodified hierarchically superhydrophilic PVDF membrane maintained efficient emulsion separation for a much shorter period (120 min). Most importantly, the surface-immobilized 8-FeOOH exhibited excellent photocatalytic activity for cleaning the oil foulants (soybean oil and crude oil) through the photo-Fenton reaction in the presence of peroxide, endowing the membrane with self-cleaning capability. As a result, the unwanted foulants were successfully removed from the membrane surface, restoring separation performance of the super hydrophilic PVDF membrane for reuse. Therefore, the self-cleaning membrane can treat more oily wastewater and produce more clean water before replacement. The mineralized superhydrophilic PVDF membrane with hierarchical composite micro-/nano structures exhibits satisfactory stability under simultaneous separation and photocatalysis cleaning, showing great potential for tricky oily wastewater treatment and oil resource recovery
Study of wide temperature range and hard protective La2O3 doped cermet based single-layer solar selective absorbing coating by laser cladding
No full textIn this paper, Ni/TiN-La2O3 single-layer cermet coating was designed and prepared on 316 L substrate by laser cladding. The coating has excellent optical properties in a wide temperature range, with a solar absorption rate (alpha) of 82% and a thermal emissivity (epsilon) of 7%. After heat treatment at 600 degrees C for 24 h, its optical performance stabilized at 78% (alpha) and 3% (epsilon), showing its excellent optical performance in a wide temperature range. The mechanical simulation, Vickers hardness test and electrochemical corrosion test also show that the coating has excellent hardness and corrosion resistance (The hardness is 87.5% higher than that of the substrate). All these advantages endow the proposed single-layer hard protective Ni/TiN-La2O3 cermet absorption coating with potential application in long-term solar energy collection
Interfacial crosslinking for highly thermally conductive and mechanically strong boron nitride/aramid nanofiber composite film
No full textAlways, the interfacial thermal resistance and the phonons scattering greatly restrict the further improvement of boron nitride nanosheets (BNNS)/polymer composites. Herein, the interfacial crosslinking approach was innovatively used to enhance the in-plane thermal conductivity (TC) and mechanical properties of the BNNS/ANFs composites. In order to achieve the interfacial crosslinking, the BNNS was aminated via melting functionalization with urea and the ANFs were activated by hydrolysis with phosphoric acid (PA). The nacre-like cross-linked aminated BNNS/reactive ANFs (C-ABNNs/R-ANFs) composite film was fabricated by vacuum-assisted filtration followed with interfacial crosslinked by condensation reaction with glutaraldehyde (GA). The interfacial crosslinking effectively reduced the interfacial thermal resistance and phonons scattering, simultaneously contributes to the stress transfer between ABNNs and R-ANFs. When the loading amount of ABNNs is 20 wt%, the inplane TC of the C-ABNNs/R-ANFs composite film is -10.15 W m(-1)K(-1) which is nearly two times higher than that of ABNNs/R-ANFs composite film (-5.59 W m(-1)K(-1))
One-dimensional NiS-CNT@Li7P3S11 nanocomposites as ionic/electronic additives for LiCoO2 based all-solid-state lithium batteries
No full textIncreasing active material content is critical to realize high energy density for all-solid-state lithium bat-teries (ASSLBs), which is generally impeded by limited ionic/electronic conductions in cathode layer. Herein, one-dimensional NiS-CNT@Li7P3S11 nanocomposites are synthesized by wet chemistry method and possess high mixed ionic/electronic conductivities. When employed as additives for LiCoO2, the NiS-CNT@Li7P3S11 nanocomposites can efficiently improve the electrochemical performances of LiCoO2 cathode in the ASSLBs. Specifically, the resultant Li/75%Li2S-24%P2S5-1%P2O5/Li10GeP2S12/LiCoO2-5%NiS-CNT@Li7P3S11 ASSLBs with 70 wt% LiCoO2 content deliver a reversible capacity of 114.3 mAh g(-1) after 50 cycles under 0.1 C and 99.6 mAh g(-1) at 0.5 C after 100 cycles at room temperature. Even if the active material LiCoO2 content increases to 80%, a high reversible discharge capacity of 124 mAh g(-1) can be achieved at 0.05 C after 25 cycles. Obviously, the excellent electrochemical performances are attributed to the improved ionic/electronic conductivities with assistance of NiS-CNT@Li7P3S11. This work provides an efficient strategy to design cathode materials with high ionic/electronic conductivities and paves the way for the practical application of ASSLBs. (C) 2021 Elsevier Ltd. All rights reserved
Inhibition of oxidative stress in vivo through enzyme-like activity of carbon dots
No full textOxidative stress is a huge challenge to human health, and effective agents for resisting this adverse ef-fect are remains limited recently. Here, an excellent enzyme-like activity of carbon dots (e-CDs) via a facile solvothermal method is reported. In addition, e-CDs exert protective effects in HUVEC cell model by decreasing apoptosis. e-CDs also efficiently diminish ROS and apoptosis damage in mice treated with D-galactose. Furthermore, e-CDs-pretreated mice shows decrease apoptotic proteins in the brain and liver, confirming that e-CDs ameliorate D-galactose induced aging. Compared with general nanozymes, biocom-patible e-CDs demonstrate their high potential for anti-aging by the inhibition of oxidative stress. (c) 2021 Elsevier Ltd. All rights reserved
Laser-Mediated antibacterial effects of Few- and Multi-Layer Ti3C2Tx MXenes
No full textTi3C2Tx nano-sheets (MXenes) with excellent light-conversion capacity have gained importance in treating infectious diseases due to their limited bacterial resistance. In this study, we exploit this property to design photothermal antibacterial therapy using few- (FX) and multi-layer (MX) Ti3C2Tx nano-sheets. We demonstrate that FX have a higher cytocompatibility and conversion of light to heat, but MX show a better efficacy in inhibiting growth of S. aureus and E. coli due to MXenes' reversible bacteria trapping. For MX (25 mu g/mL), square 37% of E. coli and square 23% of S. aureus cells survived, while the effect was less pronounced for FX with square 72% of E. coli and square 46% of S. aureus viable cells after treatment. After using 100 mu g/mL of MX, square 11% of E. coli and square 46% of S. aureus survived, while FX had only a mild effect on both species. The NIR laser treatment increased the efficacy of both materials: 100 mu g/mL of MX combined with 5 min laser treatment at 5.7 W cm(-2) completely killed both species. For FX, the treatment with 3 W cm(-2) and the highest concentration (100 mu g/mL) induced an effect comparable to MX (87% on E. coli, 95% on S.aureus). The combined NIR MXene treatment causes an irreversible cell death linked to the loss of cell integrity (DNA release quantification and bacteria debris observation)
Growth of wrinkle-free and ultra-flat Bi-layer graphene on sapphire substrate using Cu sacrificial layer
No full textThe transfer process of chemical vapor deposition graphene film leads to unavoidable crack, wrinkles, doping, and contamination, which limits its function to establish stable and high-performance devices. It raises a growing interest to fabricate high-quality graphene on the target substrate directly. Here, bi-layer graphene (BLG) film can be grown on sapphire substrate by a Cu sacrificial layer using atmospheric-pressure chemical vapor deposition. The as-obtained BLG at the interface between sapphire and Cu layer is free of wrinkles, and the corresponding surface roughness Ra is as low as 0.66 nm. The square resistance of the graphene is 898.1 ohm sq(-1), which is the lowest among the records of graphene film directly grown on nonmetal substrates
Effect of surface Nd-rich phase and oxygen content of melt-spun flakes on formation of coarse grains in hot-pressed Nd-Fe-B magnet
No full textNd-Fe-B hot-pressed (HP) magnet prepared from melt-spun MQU-F flakes features coarse grains (CG) with the average size of both 200 nm (CG(S)) and 700 nm (CG(L)) at flake boundary. The grain growth at the flake boundary of Nd2Fe14B/alpha-Fe composite HP magnet before and after diffusion of low-melting-point Pr82Cu18 phase was investigated, revealing the indispensable role of surface RE-rich phase of melt-spun flakes in the formation of CG in HP magnet. The dominant role of surface oxygen content of melt-spun flakes in the formation of CG(L) has been clarified with etching method. The HP magnet prepared from the etched flakes with dramatically decreased oxygen content exhibits the CG regions merely with homogeneous equiaxed CG(S) at flake boundary. Consequently, the coercivity (mu H-0(c)) shows significant increase while remanent magnetization (mu M-0(r)) inappreciable change. Further investigation with sieving method reveals the elimination of CG(L) via removal of the fine Nd-Fe-B flakes smaller than 54 mu m due to their much higher oxygen content, confirming the dominant role of oxygen content in the formation of CG(L). The quantitative analysis on the magnetic properties of the above HP magnets reveals the monotonic increase of coercivity (mu H-0(c)) and negligible change of remanent magnetization (mu M-0(r)) with decreased oxygen contents of Nd-Fe-B flakes. The maximum value of coercivity (mu H-0(c)) increases from 2.26 to 2.47 T as the oxygen content decreases from 0.1692 wt% to 0.079 wt%. (C) 2021 The Authors. Published by Elsevier B.V
Humidification of high-performance and multifunctional polyimide/carbon nanotube composite foams for enhanced electromagnetic shielding
No full textThough conductive polymer composite (CPC) foams have been investigated widely for electromagnetic interference (EMI) shielding owing to their low density and high EM absorption, fabricating high-performance CPC foams through a simple and easy-to-scale preparation process, as well as exploring new approach to achieve the shielding enhancement of CPC foams under mild conditions for meeting some special circumstances that needing higher shielding effectiveness (SE) in a short time, is still of great importance. In this work, multifunctional polyimide/carbon nanotube composite foams (PIF/CNT) were manufactured by the combination of effective chemical-foaming method and simple solution dipcoating approach. The resultant PIF/CNT with ultralow density exhibited the integration of excellent performances on absorbing-dominant EMI shielding with the extreme-temperature adaptability, flame retardancy, thermal insulation, infrared stealth and Joule-heating functions. On the other hand, the idea of humidifying-enhanced EMI shielding is proposed, and the EMI SE of wetted PIF/CNT samples can be massively improved due to the easy adsorption of strongly polar water molecules on the open-cell foam skeleton with hydrophilic poly (vinyl pyrrolidone). By the humidifying-drying cycles to enhance or restore the SE performance, our PIF/CNT material can be adjusted within a certain SE range to achieve intelligent electromagnetic response, providing another important guide for the design of novel intelligent EMI shields. (C) 2021 Elsevier Ltd. All rights reserved