The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,d...The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,deep space exploration,and various other fields.Cl_(2)-assisted reactive ion etching(RIE)stands out as a more effective and efficient method for patterning scalable thin films.However,neither RIE nor high-density RIE has achieved superconducting YBCO nanowires with a width smaller than 3μm.Here,we delve into the factors that limit the line width of Cl_(2)-assisted inductively coupled plasma reactive ion etching(ICP-RIE)processing and the method to elimiate them.Our approach involves utilizing Cl_(2)/Ar as etching gas and incorporating a specialized vacuum heating process after etching.Our experimental results demonstrate the successful realization of 10 nm-thick YBCO nanowires with widths as small as 0.15μm,exhibiting excellent performance in terms of their intrinsic superconducting properties.The mechanism is evidenced by X-ray photoelectron spectroscopy(XPS)analysis in comparison of nanowires with and without heating treatment,in which the residual Cl_(2) on the sidewall of nanowires evaporates and oxidizes Cu^(+)back into Cu^(2+)in an unetched state.展开更多
Finding and designing cathode oxygen reduction reaction(ORR) catalysts with high activity and stability in acidic electrolyte is essential for the large-scale application of fuel cells and metal-air batteries.Pt-based...Finding and designing cathode oxygen reduction reaction(ORR) catalysts with high activity and stability in acidic electrolyte is essential for the large-scale application of fuel cells and metal-air batteries.Pt-based alloys have emerged as potential electrocatalysts for the oxygen reduction reaction.Herein,we adapted a simple pyrolytic reduction method to grow FePt nanoalloys on hollow mesoporous carbon supports.Benefiting from the ultra-high specific surface of the hollow mesoporous carbon,the in situ formed FePt NPs were homogenously deposited on the carbon supports with size smaller than5 nm.The optimized FePt-HMCS showed a remarkably increased mass activity(MA) of 0.582 A·mg^(-1)_(Pt) at 0.75 V in ORR,being 6.3 times higher than that of commercial Pt/C(0.093 A·mg^(-1)_(Pt)).Meanwhile,the FePt NPs showed negligible decay in mass activity with 21 mV of negative shift in the half-wave potential after 5000 electrochemical cycles,which is more stable than that of commercial Pt/C(6.6% decay in MA with 30 mV of negative shift).The study demonstrated a simple strategy for controlling the alloy size with enhanced metal-support interactions to boost their promising application in fuel cells.展开更多
Methyl vinyl silicone rubber (MVQ)/polypropylene (PP) thermoplastic vulcanizate (TPV) combines the good melt processability, recyclability and sealing performance as well as biosafety, stain and fluid resistance, and ...Methyl vinyl silicone rubber (MVQ)/polypropylene (PP) thermoplastic vulcanizate (TPV) combines the good melt processability, recyclability and sealing performance as well as biosafety, stain and fluid resistance, and thus it is especially suitable in bio-safety areas and wearable electronic devices, etc. Nevertheless, the compatibility between MVQ and PP phases is poor. A big challenge on the compatibilization of MVQ/PP blends is that neither MVQ nor PP contains any reactive groups. In this study, a dual reactive compatibilizer composed of ethylenemethyl acrylate-glycidyl methacrylate terpolymer (EMA-co-GMA) and maleic anhydride grafted polypropylene (PP-g-MAH) was designed for the compatibilization of MVQ/PP blends. During melt blending, a copolymer compatibilizer at the MVQ/PP interface can be formed because of the in situ reaction between EMA-co-GMA and PP-g-MAH. The thermodynamic predict of its compatibilization effect through calculating the spreading coefficient of the in situ formed copolymer indicates that it can well compatibilize MVQ/PP blends. The experimental results show that under the GMA/MAH molar ratio of 0.5/1, the interface thickness largely increase from 102 nm for non-compatibilized blend to 406 nm, and the average size of MVQ dispersed phase largely decreases from 2.3 µm to 0.36 µm, the Tg of the two phases shifts toward each other, the mixing torque and mechanical properties of the blend are increased, all indicating its good compatibilization effect. This study provides a good compatibilizing method for immiscible MVQ/PP blends with no reactive groups in both components for the preparation of high performance MVQ/PP TPVs.展开更多
We report our recent progress in the design and simulation of a high-brightness S-band photo-injector with a ballistic bunching scheme aimed at driving an inverse Compton scattering(ICS)X-ray source.By adding a short ...We report our recent progress in the design and simulation of a high-brightness S-band photo-injector with a ballistic bunching scheme aimed at driving an inverse Compton scattering(ICS)X-ray source.By adding a short standing-wave buncher between the RF gun and first booster in a conventional S-band photo-injector,electron bunches with a 500 pC charge can be compressed to the sub-picosecond level with very limited input RF power and an unchanged basic layout of the photo-injector.Beam dynamics analysis indicates that fine tuning of the focusing strength of the gun and linac solenoid can well balance additional focusing provided by the standing wave buncher and generate a well-compensated transverse emittance.Thorough bunching dynamics simulations with different operating conditions of the buncher show that a buncher with more cells and a moderate gradient is suitable for simultaneously obtaining a short bunch duration and low emittance.In a typical case of a 9-cell buncher with a 38 MV/m gradient,an ultrashort bunch duration of 0.5 ps(corresponding to a compression ratio of>5)and a low emittance of<1 mm mrad can be readily obtained for a 500 pC electron pulse.This feasible ballistic bunching scheme will facilitate the implementation of an ultrashort pulse mode inverse Compton scattering X-ray source on most existing S-band photo-injectors.展开更多
Background:Spinal extradural arachnoid cyst is extremely rare.The longest SEACs that have been reported in previous studies involved no more than 5 spinal segments.This study presents a case of SEAC diagnosed from T9 ...Background:Spinal extradural arachnoid cyst is extremely rare.The longest SEACs that have been reported in previous studies involved no more than 5 spinal segments.This study presents a case of SEAC diagnosed from T9 to L4 and excised through a novel laminectomy/laminoplasty.Case presentation:A 22-year-old female presented with a 5-year history of progressive paraparesis and numbness in both lower limbs.MRI revealed posterolateral epidural cystic mass extending from T9-L4 with a length of 190 mm and width of 15 mm.The cyst was totally removed through surgery.The patient’s symptom was completely relieved 1 year after the surgery.There was no recurrence,compression on the spinal cord,or kyphotic deformity based on MRI and CT taken 1 year after.Conclusion:Spinal extradural arachnoid cysts are relatively uncommon but surgically curable causes of myelopathy.For symptomatic patients,early surgical intervention is suggested for restoring neurological functions.Performing laminectomy by using crainotome is safe and efficient.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFA0718800)the Natural Science Foundation of Sichuan Province(No.2023NSFSC0993)+1 种基金the National Natural Science Foundation of China(Nos.52021001,U22A20132 and 12074056)Sichuan Science and Technology Program(No.2021JDTD0010).
文摘The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,deep space exploration,and various other fields.Cl_(2)-assisted reactive ion etching(RIE)stands out as a more effective and efficient method for patterning scalable thin films.However,neither RIE nor high-density RIE has achieved superconducting YBCO nanowires with a width smaller than 3μm.Here,we delve into the factors that limit the line width of Cl_(2)-assisted inductively coupled plasma reactive ion etching(ICP-RIE)processing and the method to elimiate them.Our approach involves utilizing Cl_(2)/Ar as etching gas and incorporating a specialized vacuum heating process after etching.Our experimental results demonstrate the successful realization of 10 nm-thick YBCO nanowires with widths as small as 0.15μm,exhibiting excellent performance in terms of their intrinsic superconducting properties.The mechanism is evidenced by X-ray photoelectron spectroscopy(XPS)analysis in comparison of nanowires with and without heating treatment,in which the residual Cl_(2) on the sidewall of nanowires evaporates and oxidizes Cu^(+)back into Cu^(2+)in an unetched state.
基金financially supported by the National Natural Science Foundation of China (No.22174133)。
文摘Finding and designing cathode oxygen reduction reaction(ORR) catalysts with high activity and stability in acidic electrolyte is essential for the large-scale application of fuel cells and metal-air batteries.Pt-based alloys have emerged as potential electrocatalysts for the oxygen reduction reaction.Herein,we adapted a simple pyrolytic reduction method to grow FePt nanoalloys on hollow mesoporous carbon supports.Benefiting from the ultra-high specific surface of the hollow mesoporous carbon,the in situ formed FePt NPs were homogenously deposited on the carbon supports with size smaller than5 nm.The optimized FePt-HMCS showed a remarkably increased mass activity(MA) of 0.582 A·mg^(-1)_(Pt) at 0.75 V in ORR,being 6.3 times higher than that of commercial Pt/C(0.093 A·mg^(-1)_(Pt)).Meanwhile,the FePt NPs showed negligible decay in mass activity with 21 mV of negative shift in the half-wave potential after 5000 electrochemical cycles,which is more stable than that of commercial Pt/C(6.6% decay in MA with 30 mV of negative shift).The study demonstrated a simple strategy for controlling the alloy size with enhanced metal-support interactions to boost their promising application in fuel cells.
基金supported by the National Natural Science Foundation of China(No.51525301).
文摘Methyl vinyl silicone rubber (MVQ)/polypropylene (PP) thermoplastic vulcanizate (TPV) combines the good melt processability, recyclability and sealing performance as well as biosafety, stain and fluid resistance, and thus it is especially suitable in bio-safety areas and wearable electronic devices, etc. Nevertheless, the compatibility between MVQ and PP phases is poor. A big challenge on the compatibilization of MVQ/PP blends is that neither MVQ nor PP contains any reactive groups. In this study, a dual reactive compatibilizer composed of ethylenemethyl acrylate-glycidyl methacrylate terpolymer (EMA-co-GMA) and maleic anhydride grafted polypropylene (PP-g-MAH) was designed for the compatibilization of MVQ/PP blends. During melt blending, a copolymer compatibilizer at the MVQ/PP interface can be formed because of the in situ reaction between EMA-co-GMA and PP-g-MAH. The thermodynamic predict of its compatibilization effect through calculating the spreading coefficient of the in situ formed copolymer indicates that it can well compatibilize MVQ/PP blends. The experimental results show that under the GMA/MAH molar ratio of 0.5/1, the interface thickness largely increase from 102 nm for non-compatibilized blend to 406 nm, and the average size of MVQ dispersed phase largely decreases from 2.3 µm to 0.36 µm, the Tg of the two phases shifts toward each other, the mixing torque and mechanical properties of the blend are increased, all indicating its good compatibilization effect. This study provides a good compatibilizing method for immiscible MVQ/PP blends with no reactive groups in both components for the preparation of high performance MVQ/PP TPVs.
基金supported by National Natural Science Foundation of China(NSFC)(Nos.12005211,11905210,11975218 and 11805192).
文摘We report our recent progress in the design and simulation of a high-brightness S-band photo-injector with a ballistic bunching scheme aimed at driving an inverse Compton scattering(ICS)X-ray source.By adding a short standing-wave buncher between the RF gun and first booster in a conventional S-band photo-injector,electron bunches with a 500 pC charge can be compressed to the sub-picosecond level with very limited input RF power and an unchanged basic layout of the photo-injector.Beam dynamics analysis indicates that fine tuning of the focusing strength of the gun and linac solenoid can well balance additional focusing provided by the standing wave buncher and generate a well-compensated transverse emittance.Thorough bunching dynamics simulations with different operating conditions of the buncher show that a buncher with more cells and a moderate gradient is suitable for simultaneously obtaining a short bunch duration and low emittance.In a typical case of a 9-cell buncher with a 38 MV/m gradient,an ultrashort bunch duration of 0.5 ps(corresponding to a compression ratio of>5)and a low emittance of<1 mm mrad can be readily obtained for a 500 pC electron pulse.This feasible ballistic bunching scheme will facilitate the implementation of an ultrashort pulse mode inverse Compton scattering X-ray source on most existing S-band photo-injectors.
文摘Background:Spinal extradural arachnoid cyst is extremely rare.The longest SEACs that have been reported in previous studies involved no more than 5 spinal segments.This study presents a case of SEAC diagnosed from T9 to L4 and excised through a novel laminectomy/laminoplasty.Case presentation:A 22-year-old female presented with a 5-year history of progressive paraparesis and numbness in both lower limbs.MRI revealed posterolateral epidural cystic mass extending from T9-L4 with a length of 190 mm and width of 15 mm.The cyst was totally removed through surgery.The patient’s symptom was completely relieved 1 year after the surgery.There was no recurrence,compression on the spinal cord,or kyphotic deformity based on MRI and CT taken 1 year after.Conclusion:Spinal extradural arachnoid cysts are relatively uncommon but surgically curable causes of myelopathy.For symptomatic patients,early surgical intervention is suggested for restoring neurological functions.Performing laminectomy by using crainotome is safe and efficient.
