Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed ...Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.展开更多
Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes.Polyolefin elastomers(POE)are a typical example.Due to cost,only a ...Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes.Polyolefin elastomers(POE)are a typical example.Due to cost,only a few linear a-olefins(e.g.,1-butene,1-hexene,and 1-octene)are used as comonomers in solution polymerization in industry.However,a-olefin comonomers with other structures may have different effects on polymerization in comparison with common linear ones.Moreover,the properties of the corresponding materials may differ significantly.In this work,copolymers of ethylene with linear and endcyclized a-olefins are synthesized using a metallocene catalyst.The copolymerization of ethylene with linear a-olefins results in a higher turn-over frequency(TOF)and lower incorporation than copolymerization with end-cyclized a-olefins,which may indicate that end-cyclized a-olefins have a higher coordination probability and lower insertion rate.In this reaction,the comonomer is distributed randomly in the polymer chain and efficiently destroys crystallization.End-cyclized a-olefins exhibit a much stronger crystallization destructive capacity(CDC)in the copolymer than linear a-olefins,possibly because linear a-olefins act mainly in the radial direction of the main chain of the polymer,while end-cyclized a-olefins act mainly in the axial direction of the main chain.展开更多
In order to extend the usage of PLA-based nanocomposites, the modification of multi-walled carbon nanotubes (MWCNT) and preparation of surfactant modified carbon nanotubes (SMCNT) involved PLA nanocomposites (PLA/SMCN...In order to extend the usage of PLA-based nanocomposites, the modification of multi-walled carbon nanotubes (MWCNT) and preparation of surfactant modified carbon nanotubes (SMCNT) involved PLA nanocomposites (PLA/SMCNT) were investigated. The morphologies, electrical properties and crystallization behavior of PLA/SMCNT composites were investigated. The TEM images indicated that SMCNTs were dispersed homogenously in the PLA matrix without forming aggregates. The electrical conductivity of PLA/SMCNT was greatly improved and the percolation threshold of PLA/SMCNT was calculated to be 0.61% which is much lower than 1.45% of PLA/MWCNT composite. The crystallization behavior suggested that SDBS together with MWCNT acted as heterogeneous nucleating agent and accelerated the nucleation. Meanwhile, the SMCNT also devoted further restrained effect to spherulites growth due to its well dispersion and improved compatibility with matrix.展开更多
A Ni(Ⅱ)coordination complex 1 with a novel boron-oxamido radical ligand was synthesized and isolated.Reactions of 1 with N,N-dimethyl-4-pyridinamine(DMAP)and 4,4'-bpy resulted in 2 and 3,respectively,accompanied ...A Ni(Ⅱ)coordination complex 1 with a novel boron-oxamido radical ligand was synthesized and isolated.Reactions of 1 with N,N-dimethyl-4-pyridinamine(DMAP)and 4,4'-bpy resulted in 2 and 3,respectively,accompanied by the spin state transition from S=1/2 to S=3/2.Both 2 and 3 were isolated as stable crystals and characterized to feature an S=3/2 spin state,with the S=1 Ni(Ⅱ)atoms ferromagnetically coupled with the ligand-centred radicals,by SQUID measurement and EPR spectroscopy.Complex 3 represents the first example of one-dimensional magnetic chain constructed by S=3/2 Ni(Ⅱ)-radical units.展开更多
Residual water-induced decomposition is one of the dominant reasons for the decay of power conversion efficiency (PCE) in perovskite solar cells (Pero-SCs). To solve this problem, we introduce traces amount of sodium ...Residual water-induced decomposition is one of the dominant reasons for the decay of power conversion efficiency (PCE) in perovskite solar cells (Pero-SCs). To solve this problem, we introduce traces amount of sodium hyaluronate (SH) into the perovskite active layer to reduce the remaining water during the preparation of perovskite films. Unlike the traditionally adopted passive protection of perovskite from exterior water by low surface energy coatings, this study provides active control of the interior water by the addition of a water adsorbent into the perovskite films. The encapsulated Pero-SCs with SH retain approximately 70% of their initial PCE in 4000 h, while those without SH retain 32% of their initial PCE in 1000 h under the dark and ambient atmosphere. The unencapsulated Pero-SCs with SH stored in N2 atmosphere maintain over 94% of the initial PCE in 3000 h at room temperature away from light and remain over 88% of the initial PCE in 2000 h even the devices are heated to 70 °C. It has been proven that the improved stability is mainly due to the well-controlled residual water in perovskite films. Concomitantly, the PCE of p-i-n solar cells based on (FAPbI3)0.85(MAPbBr3)0.15 is improved from 19.34% to 21.54%.展开更多
Natural bone is a composite tissue made of organic and inorganic components,showing piezoelectricity.Whitlockite(WH),which is a natural magnesium-containing calcium phosphate,has attracted great attention in bone form...Natural bone is a composite tissue made of organic and inorganic components,showing piezoelectricity.Whitlockite(WH),which is a natural magnesium-containing calcium phosphate,has attracted great attention in bone formation recently due to its unique piezoelectric property after sintering treatment and sustained release of magnesium ion(Mg^(2+)).Herein,a composite scaffold(denoted as PWH scaffold)composed of piezoelectric WH(PWH)and poly(ε-caprolactone)(PCL)was 3D printed to meet the physiological demands for the regeneration of neuro-vascularized bone tissue,namely,providing endogenous electric field at the defect site.The sustained release of Mg^(2+)from the PWH scaffold,displaying multiple biological activities,and thus exhibits a strong synergistic effect with the piezoelectricity on inhibiting osteoclast activation,promoting the neurogenic,angiogenic,and osteogenic differentiation of bone marrow mesenchymal stromal cells(BMSCs)in vitro.In a rat calvarial defect model,this PWH scaffold is remarkably conducive to efficient neo-bone formation with rich neurogenic and angiogenic expressions.Overall,this study presents the first example of biomimetic piezoelectric scaffold with sustained Mg^(2+)release for promoting the regeneration of neuro-vascularized bone tissue in vivo,which offers new insights for regenerative medicine.展开更多
基金the scientific research project of China Petroleum&Chemical Corporation(Grant No.411048).
文摘Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.
文摘Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes.Polyolefin elastomers(POE)are a typical example.Due to cost,only a few linear a-olefins(e.g.,1-butene,1-hexene,and 1-octene)are used as comonomers in solution polymerization in industry.However,a-olefin comonomers with other structures may have different effects on polymerization in comparison with common linear ones.Moreover,the properties of the corresponding materials may differ significantly.In this work,copolymers of ethylene with linear and endcyclized a-olefins are synthesized using a metallocene catalyst.The copolymerization of ethylene with linear a-olefins results in a higher turn-over frequency(TOF)and lower incorporation than copolymerization with end-cyclized a-olefins,which may indicate that end-cyclized a-olefins have a higher coordination probability and lower insertion rate.In this reaction,the comonomer is distributed randomly in the polymer chain and efficiently destroys crystallization.End-cyclized a-olefins exhibit a much stronger crystallization destructive capacity(CDC)in the copolymer than linear a-olefins,possibly because linear a-olefins act mainly in the radial direction of the main chain of the polymer,while end-cyclized a-olefins act mainly in the axial direction of the main chain.
文摘In order to extend the usage of PLA-based nanocomposites, the modification of multi-walled carbon nanotubes (MWCNT) and preparation of surfactant modified carbon nanotubes (SMCNT) involved PLA nanocomposites (PLA/SMCNT) were investigated. The morphologies, electrical properties and crystallization behavior of PLA/SMCNT composites were investigated. The TEM images indicated that SMCNTs were dispersed homogenously in the PLA matrix without forming aggregates. The electrical conductivity of PLA/SMCNT was greatly improved and the percolation threshold of PLA/SMCNT was calculated to be 0.61% which is much lower than 1.45% of PLA/MWCNT composite. The crystallization behavior suggested that SDBS together with MWCNT acted as heterogeneous nucleating agent and accelerated the nucleation. Meanwhile, the SMCNT also devoted further restrained effect to spherulites growth due to its well dispersion and improved compatibility with matrix.
基金the National Key R&D Program of China(Grant 2018YFA0306004)the National Natural Science Foundation of China(Grant 21525102)for financial support.
文摘A Ni(Ⅱ)coordination complex 1 with a novel boron-oxamido radical ligand was synthesized and isolated.Reactions of 1 with N,N-dimethyl-4-pyridinamine(DMAP)and 4,4'-bpy resulted in 2 and 3,respectively,accompanied by the spin state transition from S=1/2 to S=3/2.Both 2 and 3 were isolated as stable crystals and characterized to feature an S=3/2 spin state,with the S=1 Ni(Ⅱ)atoms ferromagnetically coupled with the ligand-centred radicals,by SQUID measurement and EPR spectroscopy.Complex 3 represents the first example of one-dimensional magnetic chain constructed by S=3/2 Ni(Ⅱ)-radical units.
基金supported by the National Natural Science Foundation of China(51673139,91633301)a Priority Academic Program Development of Jiangsu Higher Education Institutions,State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials.
文摘Residual water-induced decomposition is one of the dominant reasons for the decay of power conversion efficiency (PCE) in perovskite solar cells (Pero-SCs). To solve this problem, we introduce traces amount of sodium hyaluronate (SH) into the perovskite active layer to reduce the remaining water during the preparation of perovskite films. Unlike the traditionally adopted passive protection of perovskite from exterior water by low surface energy coatings, this study provides active control of the interior water by the addition of a water adsorbent into the perovskite films. The encapsulated Pero-SCs with SH retain approximately 70% of their initial PCE in 4000 h, while those without SH retain 32% of their initial PCE in 1000 h under the dark and ambient atmosphere. The unencapsulated Pero-SCs with SH stored in N2 atmosphere maintain over 94% of the initial PCE in 3000 h at room temperature away from light and remain over 88% of the initial PCE in 2000 h even the devices are heated to 70 °C. It has been proven that the improved stability is mainly due to the well-controlled residual water in perovskite films. Concomitantly, the PCE of p-i-n solar cells based on (FAPbI3)0.85(MAPbBr3)0.15 is improved from 19.34% to 21.54%.
基金This work was supported by the National Natural Science Foundation of China(U22A20159,52003161)the Central Universities(buctrc202220),and the SINOPEC project(421029).
文摘Natural bone is a composite tissue made of organic and inorganic components,showing piezoelectricity.Whitlockite(WH),which is a natural magnesium-containing calcium phosphate,has attracted great attention in bone formation recently due to its unique piezoelectric property after sintering treatment and sustained release of magnesium ion(Mg^(2+)).Herein,a composite scaffold(denoted as PWH scaffold)composed of piezoelectric WH(PWH)and poly(ε-caprolactone)(PCL)was 3D printed to meet the physiological demands for the regeneration of neuro-vascularized bone tissue,namely,providing endogenous electric field at the defect site.The sustained release of Mg^(2+)from the PWH scaffold,displaying multiple biological activities,and thus exhibits a strong synergistic effect with the piezoelectricity on inhibiting osteoclast activation,promoting the neurogenic,angiogenic,and osteogenic differentiation of bone marrow mesenchymal stromal cells(BMSCs)in vitro.In a rat calvarial defect model,this PWH scaffold is remarkably conducive to efficient neo-bone formation with rich neurogenic and angiogenic expressions.Overall,this study presents the first example of biomimetic piezoelectric scaffold with sustained Mg^(2+)release for promoting the regeneration of neuro-vascularized bone tissue in vivo,which offers new insights for regenerative medicine.