In this study, acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization. The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly (acrylic acid) (WPU-PAA) dispersion and the films were systematically investigated. The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid, leading to enhancement of the mechanical properties and water resistance of WPU-PAA films. Notably, with the increase in content of acrylic acid, the tensile strength, Young’s modulus, and toughness of the WPU-PAA-110 film increased by 3 times, and 8 times, and 2.4 times compared with WPU-PAA-80, respectively. The WPU-PAA-100 film showed the best water resistance, and the water absorption rate at 96 h was only 3.27%. This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.
Cathode material SmBaCoFeO5+δ (SBCF) was synthesized by a combined EDTA-citrate complexing sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), AC impendence spectroscopy, respectively. The results showed that the SBCF cathode had an orthorhombic perovskite-structure and formed a good contact with the Ce0.9Gd0.1O1.95 (GDC) electrolyte after sintering at 950°C for 2h. Based on symmetric cell test, area specific resistance of SBCF on GDC electrolyte was as low as 0.1Ω cm2 at 800°C. The maximum power densities of a cell using the SBCF cathode are 431 mWcm−2, 313mWcm−2 and 200mWcm−2 at 800°C, 750°C and 700°C, respectively. Preliminary results demonstrate that SBCF is a very promising cathode material for application in intermediate-temperature solid oxide fuel cells (IT-SOFCs).
This paper aimed at the high added value use of a deoiled asphaltene.Monodispersed highly graphitized graphitic spheres (GSs)with high thermal stability were synthesized by vacuum thermal processing followed chemical vapor deposition (CVD).The carbon microbeds and the synthesized GSs were compared by means of SEM,HRTEM,XRD and TGA.Vacuum thermal processed GSs are of high degree of graphitization and good thermal stability.The disordered structure of carbon microbeds were thermodynamically propelled to transit to the graphitic structure,forming the GSs.
Lithium-sulfur batteries with high energy density (2600 Wh•kg -1 ) and theoretical capacity (1675 mAh•g -1 ) have attracted much attention.Furthermore, as a cathode active material, sulfur has prominent advantages such as rich in natural resources, low cost and environmental friendliness.Attributed to the above merits, lithium-sulfur batteries deemed to be one of the most promising energy storage devices.However, poor utilization of sulfur and the shuttle effect of lithium polysulfides (LiPSs) causes dramatic capacity degradation, which severely restricts the commercial application of lithium-sulfur batteries.These problems are mainly attributed to the insulating nature of sulfur and its final discharge products (Li2S2/Li2S), which reduces the sulfur utilization, as well as the poor adsorption capability and slow reaction kinetics, which give rise to the shuttle effect of soluble LiPSs.To solve the above problems, carbon materials are regarded as the most suitable cathode materials for lithium-sulfur batteries, because its superior electrical conductivity and rich porous structure can effectively improve the sulfur utilization and mitigate the shuttle effect of LiPSs.However, the shuttling of LiPSs is difficult to suppressed completely due to the weak adsorption interaction between nonpolar carbon materials and polar LiPSs.Based on this, heteroatom doping is beneficial to enrich the chemical adsorption sites of LiPSs in carbon materials, enhancing the interaction between carbon materials and LiPSs.Thus, the shuttle effect of LiPSs is efficiently suppressed and the cycle stability of lithium-sulfur batteries is improved.Hence, N, P co-doped reduced graphene oxide (NPG) with hierarchical porous structure was prepared by one-step high-temperature reduction method and used for the polypropylene (PP) separator modification of lithium-sulfur batteries.The highly conductive NPG with abundant hierarchical porous structure provides a large number of anchor sites for LiPSs and sufficient ion/electron transport channels, facilitating the conversion of the soluble intermediates and efficiently suppressing the shuttle effect of LiPSs.In consequence, the NPG/PP modified separator can effectively inhibit the shuttle of LiPSs and improve the sulfur utilization.The results show that the cells with NPG/PP modified separator exhibit excellent cycling performance (the degradation per cycle is only 0.052% and the capacity remains at 612.5 mAh•g -1 after 500 cycles at 1 C) and excellent rate performance (high specific capacity of 617.9 mAh•g -1 at 2 C).This idea of constructing hierarchical porous N, P co-doped rGO modified separators provides a new strategy for the study of lithium-sulfur battery.
We report a multi-mode interference-based optical gate switch using a Ge(2)Sb(2)Te(5) thin film with a diameter of only 1 µm. The switching operation was demonstrated by laser pulse irradiation. This switch had a very wide operating wavelength range of 100 nm at around 1575 nm, with an average extinction ratio of 12.6 dB. Repetitive switching over 2,000 irradiation cycles was also successfully demonstrated. In addition, self-holding characteristics were confirmed by observing the dynamic responses, and the rise and fall times were 130 ns and 400 ns, respectively.
Monitoring and understanding long-term fate and regenerative therapy of administrated stem cells in vivo is of great importance. Herein we report organic nanodots with aggregation-induced emission characteristics (AIE dots) for long-term tracking of adipose-derived stem cells (ADSCs) and their regenerative capacity in living mice. The AIE dots possess high fluorescence (with a high quantum yield of 25 ± 1%), excellent biological and photophysical stabilities, low in vivo toxicity, and superb retention in living ADSCs with negligible interference on their pluripotency and secretome. These AIE dots also exhibit superior in vitro cell tracking capability compared to the most popular commercial cell trackers, PKH26 and Qtracker 655. In vivo quantitative studies with bioluminescence and GFP labeling as the controls reveal that the AIE dots can precisely and quantitatively report the fate of ADSCs and their regenerative capacity for 42 days in an ischemic hind limb bearing mouse model.
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