Commonly used flow improvers in oilfields,such as ethylene–vinyl acetate copolymer(EVA),poly(octadecyl acrylate)(POA),and polymethylsilsesquioxane(PMSQ)are proven to be effective to enhance the flowability of crude o...Commonly used flow improvers in oilfields,such as ethylene–vinyl acetate copolymer(EVA),poly(octadecyl acrylate)(POA),and polymethylsilsesquioxane(PMSQ)are proven to be effective to enhance the flowability of crude oil.However,the addition of these flow improvers may change the stability of the emulsion and make the crude oil treatment process challenging.In this research,the impacts of different flow improvers on the interfacial properties of the emulsions containing asphaltenes are systematically investigated.The co-adsorption behaviors of the flow improvers and asphaltenes are analyzed through dynamic interfacial tension(DIFT).The rheological properties of the interfacial layer after the adsorption are explored via dilational viscoelasticity.Significant difference is observed in the structural properties of the interface adsorbed by different flow improvers,which is attributed to different interactions between the flow improvers and asphaltenes.To investigate these interactions,conductivity,asphaltenes precipitation,dynamic light scattering(DLS),and contact angle experiments are conducted systematically.Results show that EVA and POA can alter the interfacial properties by changing the asphaltene dispersion state.The interaction between EVA and asphaltenes is stronger than that between POA and asphaltenes due to the difference in molecular structures.Unlike EVA and POA,the change of interfacial property with the addition of PMSQ is attributed to the partial adsorption of asphaltenes on PMSQ.展开更多
MnO_(2)has emerged as one of the favored cathode materials for aqueous zinc ion batteries(AZIBs)due to its high theoretical capacity and abundant crystalline structures.However,MnO_(2)cathode generally suffers from po...MnO_(2)has emerged as one of the favored cathode materials for aqueous zinc ion batteries(AZIBs)due to its high theoretical capacity and abundant crystalline structures.However,MnO_(2)cathode generally suffers from poor electrical conductivity and rapid capacity degradation due to unavoidable manganese dissolution during cycling,limiting their further utilization.In this study,we modify the d-band center of Mn by introducing non-precious metal Bi atoms into the MnO_(2)system,thereby strengthening the Mn-O bonding to inhibit manganese dissolution.Theoretical calculations reveal that the d-band center of Mn in Bi-MnO_(2)shifts upward,promoting electron transfer from O 2p orbitals to Mn-O bonding orbitals.This enhances the Mn-O bond strength,stabilizing Mn atoms in the crystal lattice and reducing manganese solvation loss.As a result,the conductivity and cyclic stability of Bi-MnO_(2)are significantly improved.The results demonstrate that Bi-MnO_(2)exhibits outstanding electrochemical properties,with a capacity of 392.3 mAh g^(-1)after 100 cycles at 0.2 A g^(-1)and a capacity retention of 83.25%after 5000 cycles at 1.0 A g^(-1).This study presents a new approach to address the manganese dissolution issue,which could further advance the application of d-band center theory in MnO_(2)materials.展开更多
X-rays are widely used in probing inside information nondestructively,enabling broad applications in the medical radiography and electronic industries.X-ray imaging based on emerging lead halide perovskite scintillato...X-rays are widely used in probing inside information nondestructively,enabling broad applications in the medical radiography and electronic industries.X-ray imaging based on emerging lead halide perovskite scintillators has received extensive attention recently.However,the strong self-absorption,relatively low light yield and lead toxicity of these perovskites restrict their practical applications.Here,we report a series of nontoxic double-perovskite scintillators of Cs_(2)Ag_(0.6)Na_(0.4)In_(1-y)Bi_(y)Cl_(6).By controlling the content of the heavy atom Bi^(3+),the X-ray absorption coefficient,radiative emission efficiency,light yield and light decay were manipulated to maximise the scintillator performance.A light yield of up to 39,000±7000 photons/MeV for Cs_(2)Ag_(0.6)Na_(0.4)In_(0.85)Bi_(0.15)Cl_(6) was obtained,which is much higher than that for the previously reported lead halide perovskite colloidal CsPbBr_(3)(21,000 photons/MeV).The large Stokes shift between the radioluminescence(RL)and absorption spectra benefiting from self-trapped excitons(STEs)led to a negligible selfabsorption effect.Given the high light output and fast light decay of this scintillator,static X-ray imaging was attained under an extremely low dose of ∼1μGy_(air),and dynamic X-ray imaging of finger bending without a ghosting effect was demonstrated under a low-dose rate of 47.2μGy_(air) s^(−1).After thermal treatment at 85℃ for 50 h followed by X-ray irradiation for 50 h in ambient air,the scintillator performance in terms of the RL intensity and X-ray image quality remained almost unchanged.Our results shed light on exploring highly competitive scintillators beyond the scope of lead halide perovskites,not only for avoiding toxicity but also for better performance.展开更多
基金supported by the National Natural Science Foundation of China(51704315)。
文摘Commonly used flow improvers in oilfields,such as ethylene–vinyl acetate copolymer(EVA),poly(octadecyl acrylate)(POA),and polymethylsilsesquioxane(PMSQ)are proven to be effective to enhance the flowability of crude oil.However,the addition of these flow improvers may change the stability of the emulsion and make the crude oil treatment process challenging.In this research,the impacts of different flow improvers on the interfacial properties of the emulsions containing asphaltenes are systematically investigated.The co-adsorption behaviors of the flow improvers and asphaltenes are analyzed through dynamic interfacial tension(DIFT).The rheological properties of the interfacial layer after the adsorption are explored via dilational viscoelasticity.Significant difference is observed in the structural properties of the interface adsorbed by different flow improvers,which is attributed to different interactions between the flow improvers and asphaltenes.To investigate these interactions,conductivity,asphaltenes precipitation,dynamic light scattering(DLS),and contact angle experiments are conducted systematically.Results show that EVA and POA can alter the interfacial properties by changing the asphaltene dispersion state.The interaction between EVA and asphaltenes is stronger than that between POA and asphaltenes due to the difference in molecular structures.Unlike EVA and POA,the change of interfacial property with the addition of PMSQ is attributed to the partial adsorption of asphaltenes on PMSQ.
基金supported by the Beijing Natural Science Foundation(No.2202050).
文摘MnO_(2)has emerged as one of the favored cathode materials for aqueous zinc ion batteries(AZIBs)due to its high theoretical capacity and abundant crystalline structures.However,MnO_(2)cathode generally suffers from poor electrical conductivity and rapid capacity degradation due to unavoidable manganese dissolution during cycling,limiting their further utilization.In this study,we modify the d-band center of Mn by introducing non-precious metal Bi atoms into the MnO_(2)system,thereby strengthening the Mn-O bonding to inhibit manganese dissolution.Theoretical calculations reveal that the d-band center of Mn in Bi-MnO_(2)shifts upward,promoting electron transfer from O 2p orbitals to Mn-O bonding orbitals.This enhances the Mn-O bond strength,stabilizing Mn atoms in the crystal lattice and reducing manganese solvation loss.As a result,the conductivity and cyclic stability of Bi-MnO_(2)are significantly improved.The results demonstrate that Bi-MnO_(2)exhibits outstanding electrochemical properties,with a capacity of 392.3 mAh g^(-1)after 100 cycles at 0.2 A g^(-1)and a capacity retention of 83.25%after 5000 cycles at 1.0 A g^(-1).This study presents a new approach to address the manganese dissolution issue,which could further advance the application of d-band center theory in MnO_(2)materials.
基金the support from the National Key Research and Development Program of China(2017YFA0207700)Outstanding Youth Fund of Zhejiang Natural Science Foundation of China(LR18F050001)National Natural Science Foundation of China(61804134,61525106,U1809204).
文摘X-rays are widely used in probing inside information nondestructively,enabling broad applications in the medical radiography and electronic industries.X-ray imaging based on emerging lead halide perovskite scintillators has received extensive attention recently.However,the strong self-absorption,relatively low light yield and lead toxicity of these perovskites restrict their practical applications.Here,we report a series of nontoxic double-perovskite scintillators of Cs_(2)Ag_(0.6)Na_(0.4)In_(1-y)Bi_(y)Cl_(6).By controlling the content of the heavy atom Bi^(3+),the X-ray absorption coefficient,radiative emission efficiency,light yield and light decay were manipulated to maximise the scintillator performance.A light yield of up to 39,000±7000 photons/MeV for Cs_(2)Ag_(0.6)Na_(0.4)In_(0.85)Bi_(0.15)Cl_(6) was obtained,which is much higher than that for the previously reported lead halide perovskite colloidal CsPbBr_(3)(21,000 photons/MeV).The large Stokes shift between the radioluminescence(RL)and absorption spectra benefiting from self-trapped excitons(STEs)led to a negligible selfabsorption effect.Given the high light output and fast light decay of this scintillator,static X-ray imaging was attained under an extremely low dose of ∼1μGy_(air),and dynamic X-ray imaging of finger bending without a ghosting effect was demonstrated under a low-dose rate of 47.2μGy_(air) s^(−1).After thermal treatment at 85℃ for 50 h followed by X-ray irradiation for 50 h in ambient air,the scintillator performance in terms of the RL intensity and X-ray image quality remained almost unchanged.Our results shed light on exploring highly competitive scintillators beyond the scope of lead halide perovskites,not only for avoiding toxicity but also for better performance.
