BACKGROUND Gastric phytobezoars(GPBs)are very common in northern China.Combined therapy involving carbonated beverage consumption and endoscopic lithotripsy has been shown to be effective and safe.Existing studies on ...BACKGROUND Gastric phytobezoars(GPBs)are very common in northern China.Combined therapy involving carbonated beverage consumption and endoscopic lithotripsy has been shown to be effective and safe.Existing studies on this subject are often case reports highlighting the successful dissolution of phytobezoars through Coca-Cola consumption.Consequently,large-scale prospective investigations in this domain remain scarce.Therefore,we conducted a randomized controlled trial to examine the effects of Coca-Cola consumption on GPBs.AIM To evaluate the impact of Coca-Cola on GPBs,including the dissolution rate,medical expenses,ulcer rate,and operation time.METHODS A total of 160 consecutive patients diagnosed with GPBs were allocated into two groups(a control group and an intervention group)through computer-generated randomization.Patients in the intervention group received a Coca-Cola-based regimen(Coca-Cola 2000-4000 mL per day for 7 d),while those in the control group underwent emergency fragmentation.RESULTS Complete dissolution of GPBs was achieved in 100% of the patients in the intervention group.The disparity in expenses between the control group and intervention group(t=25.791,P=0.000)was statistically significant,and the difference in gastric ulcer occurrence between the control group and intervention group(χ^(2)=6.181,P=0.013)was also statistically significant.CONCLUSION Timely ingestion of Coca-Cola yields significant benefits,including a complete dissolution rate of 100%,a low incidence of gastric ulcers,no need for fragmentation and reduced expenses.展开更多
目的探讨牛鼻子引流(nose ring drain,NRD)技术结合Ilizarov环形外固定一期治疗GustiloⅢA型Pilon骨折的疗效。方法2017年3月—2019年12月,收治GustiloⅢA型Pilon骨折患者17例。其中男11例,女6例;年龄24~63岁,平均38.2岁。交通事故伤3例...目的探讨牛鼻子引流(nose ring drain,NRD)技术结合Ilizarov环形外固定一期治疗GustiloⅢA型Pilon骨折的疗效。方法2017年3月—2019年12月,收治GustiloⅢA型Pilon骨折患者17例。其中男11例,女6例;年龄24~63岁,平均38.2岁。交通事故伤3例,高处坠落伤13例,贯通伤1例。急诊入院13例,骨折手术治疗后创面感染4例。合并腓骨骨折2例、外踝骨折3例。采用NRD技术结合Ilizarov环形外固定一期治疗。结果患者均获随访,随访时间8~12个月,平均9.9个月。创面均Ⅰ期愈合,4例术前感染患者随访期间无复发。17例患者术后3~7个月(平均4.5个月)骨折愈合后拆除外固定物。末次随访时,踝关节Kofoe评分中疼痛评分40~50分,平均44分;功能评分17~27分,平均25分;活动度评分8~18分,平均14分;获优8例,良7例,可1例,差1例。结论NRD技术结合Ilizarov环形外固定一期治疗GustiloⅢA型Pilon骨折,骨折固定及引流效果良好,大大降低了传统治疗方案并发症发生风险,减少了手术次数。展开更多
We present a series of results acquired at a 2-kilometer distance using our lidar system under several weather conditions, clear, cloudy, light rain, moderately foggy, and night. The experimental results show that gho...We present a series of results acquired at a 2-kilometer distance using our lidar system under several weather conditions, clear, cloudy, light rain, moderately foggy, and night. The experimental results show that ghost imaging lidar via spar-sity constraints can realize imaging in all these weather conditions.展开更多
Water temperature not only affects the solubility of gas in water but can also be an important factor in the dissipation process of supersaturated total dissolved gas （TDG）. The quantitative relationship between the...Water temperature not only affects the solubility of gas in water but can also be an important factor in the dissipation process of supersaturated total dissolved gas （TDG）. The quantitative relationship between the dissipation process and temperature has not been previously described. This relationship affects the accurate evaluation of the dissipation process and the subsequent biological effects. This article experimentally investigates the impact of temperature on supersaturated TDG dissipation in static and turbulent conditions. The results show that the supersaturated TDG dissipation coefficient increases with the temperature and turbulence intensity. The quantitative relationship was verified by straight flume experiments. This study enhances our understanding of the dissipation of supersaturated TDG. Furthermore, it provides a scientific foundation for the accurate prediction of the dissipation process of supersaturated TDG in the downstream area and the negative imp）acts of high dam projects on aquatic ecosystems.展开更多
As major contributor to the blue carbon sink,intertidal zones play a crucial role in the global carbon cycle.In recent years,more attention has been given to the carbon cycle in intertidal wetlands.However,due to high...As major contributor to the blue carbon sink,intertidal zones play a crucial role in the global carbon cycle.In recent years,more attention has been given to the carbon cycle in intertidal wetlands.However,due to highly variable and uncertain environmental conditions,it is difficult to clarify the quantitative relationship between soil respiration and environmental factors through in-situ experiments.In this study,the response of soil respiration characteristics to variations in the temperature and water table was investigated using a monitoring apparatus of CO_(2)flux at the soil-air interface in the intertidal zone.The results showed that soil respiration flux was significantly correlated with temperature,and the correlation best fitted the DoseResp function.Meanwhile,the respiration flux was enhanced with the descent of water table,a relationship could be described by a quadratic function.The effect of the water table on soil respiration became more pronounced with the rise of temperature.These results provide significant clarification of the impact of human activities on the carbon cycle in bare intertidal zones and as well as support for numerical simulations of the carbon cycle in bare intertidal zones.展开更多
Super-resolution(SR)imaging has been widely used in several fields like remote sensing and microscopy.However,it is challenging for existing SR approaches to capture SR images in a single shot,especially in dynamic im...Super-resolution(SR)imaging has been widely used in several fields like remote sensing and microscopy.However,it is challenging for existing SR approaches to capture SR images in a single shot,especially in dynamic imaging scenarios.展开更多
Inorganic perovskitenanostructures have attracted considerable attention for their tunable band gaps and excellent optoelectronic properties.It is inevitable that phase segregation of halide perovskite usually occurs ...Inorganic perovskitenanostructures have attracted considerable attention for their tunable band gaps and excellent optoelectronic properties.It is inevitable that phase segregation of halide perovskite usually occurs in mixed-halide perovskites under a focused laser llumination,which caused by photo-induced halide-ion segregation.Here,we reported an uniform perovskite alloy nanowires via a chemical vapor deposition(CvD)method.Microstructural characterization reveals that these perovskite nanowires have independent linear morphology_with high-quality crystalline.Micro-photoluminescence(PL)spectra exhibit that these nanowire structures show a dual-wavelength emissions at 690 and 570 nm,respectively.Additionally,time-dependent PL intensity of the emission peak at 690 nm increased by the decrease of the emission peak at 570 nm under a focused laser llumination,indicating the formation of phase segregation at the excited positions.Moreover,based on these as-grown halide perovskite CsPbBr2.52lo.48 nanowires,a reasonably optical switch is designed and constructed.This optical switch may have potential applications in timed blasting system and time-delay circuit in the future.展开更多
Bandgap engineering of semiconductor nanowires or nanoribbons(NRs)offers a promising material foundation for multifunctional integrated optoelectronic devices and circuits.Among these materials,all-inorganic halide pe...Bandgap engineering of semiconductor nanowires or nanoribbons(NRs)offers a promising material foundation for multifunctional integrated optoelectronic devices and circuits.Among these materials,all-inorganic halide perovskites have emerged as a leading candidate for next-generation photoelectronic applications due to their outstanding optoelectronic properties.In this work,we report the direct synthesis of high-quality bandgap gradient lead halide perovskite(CsPbCl_(3−3x)Br_(3x)and CsPbBr_(3−3x)I_(3x)(x=0-1))NRs using a magnetic-pulling source-moving chemical-vapor-deposition(CVD)method.Microstructural characterizations reveal that these as-grown NRs possess high-quality single crystalline structures with continuously tunable compositions.The photoluminescence emissions of these perovskite NRs can be finely tuned across the entire visible spectrum(417-702 nm).Furthermore,photodetectors based on these perovskite NRs demonstrate exceptional photoelectric performance,including a high I_(ON)/I_(OFF)ratio(10^(4)),superior responsivity(37.5 A/W),and remarkable detectivity(2.81×10^(13)Jones).A spatially resolved imaging sensor based on these perovskite NRs is also demonstrated,indicating promising applications in photoelectronic imaging circuits.These bandgap-tunable perovskite NRs provide a versatile materials platform for future integrated devices in electronics and optoelectronics.展开更多
根据国际电信联盟关于IMT-2030愿景,第6代移动通信系统(the 6th generation mobile networks,6G)的覆盖服务需求将从单场景覆盖向多场景覆盖扩展,6G基础设施的部署也将逐步从2D覆盖向3D覆盖扩展、从局部覆盖向全球覆盖扩展、从中低频段...根据国际电信联盟关于IMT-2030愿景,第6代移动通信系统(the 6th generation mobile networks,6G)的覆盖服务需求将从单场景覆盖向多场景覆盖扩展,6G基础设施的部署也将逐步从2D覆盖向3D覆盖扩展、从局部覆盖向全球覆盖扩展、从中低频段融合使用向更高频段按需开启.上述需求使得6G在提升容量的同时,需要进一步考虑无线覆盖扩展需求.本文针对如何在6G网络结构时空尺度跨度大、全场景业务需求差异大、超密集覆盖能耗大等关键挑战下实现容量和能效约束下的覆盖能力扩展这一重大科学问题,首先提出了面向6G无线覆盖扩展的智能柔性组网架构;其次研究了面向6G无线覆盖扩展的关键技术,包括面向6G广域覆盖的多维立体空天地覆盖扩展技术、面向深度覆盖的超密集异构覆盖扩展技术和面向6G平滑度覆盖的超高速移动覆盖扩展技术;接着分析了基于语义通信的覆盖扩展技术;最后给出了6G全场景无线覆盖扩展仿真验证,通过定义6G无线覆盖扩展技术指标体系,进行了典型场景的覆盖性能仿真验证.展开更多
Dyslipidemia affects approximately half of all people with gout,and prior Mendelian randomization analysis suggested a causal role for elevated triglycerides in hyperuricemia(HU),but the underlying mechanisms remain e...Dyslipidemia affects approximately half of all people with gout,and prior Mendelian randomization analysis suggested a causal role for elevated triglycerides in hyperuricemia(HU),but the underlying mechanisms remain elusive.We hypothesize that dyslipi-demia promotes hepatic urate biosynthesis in HU and gout and fatty acid(FA)oxidation(FAO)drives this process.Here we devel-oped a targeted metabolomics to quantify major metabolites in purine metabolic pathway in the sera of a human cohort with HU,gout,and normaluricemic controls.We found that the levels of major purine metabolites and multiple FAs were significantly elevated in HU and gout groups compared to normouricemic controls,whereas hypoxathine showed opposite trend.Furthermore,the levels of multiple serum FAs were positively correlated with urate,xanthine,and inosine but negatively with hypoxanthine,which was also observed in a murine model of high-fat diet-induced HU.Using a stable isotope-labeled metabolic flux assay,we discovered that exogenous hypoxanthine plays a key role in urate synthesis.Moreover,FAO-induced hypoxia-inducible factor 1 alpha(HIF-1α)activation upregulated 5ʹ-nucleotidase II(NT5C2)and xanthine dehydrogenase(XDH)levels to facilitate hypox-anthine uptake from the blood to the liver and activation of urate biosynthesis.Our findings were further supported by data in human hepatocytes and 50 paired serum and liver tissues from liver transplant donors.Together,this study uncovers a mecha-nism by which FAO promotes hepatic urate synthesis by activating HIF-1α-NT5C2/XDH pathways,directly linking lipid metabo-lism to HU.展开更多
In DC distributed power systems(DPSs),the complex impedance interactions possibly lead to DC bus voltage oscillation or collapse.In previous research,the stability analysis of DPSs is implemented based on mathematical...In DC distributed power systems(DPSs),the complex impedance interactions possibly lead to DC bus voltage oscillation or collapse.In previous research,the stability analysis of DPSs is implemented based on mathematical analysis in control theory.The specific mechanisms of the instability of the cascade system have not been intuitively clarified.In this paper,the stability analysis of DPSs based on the traditional Nyquist criterion is simplified to the resonance analysis of the seriesconnected port impedance(Z=R+jX)of source and load converters.It reveals that the essential reason for impedance instability of a DC cascade system is that the negative damping characteristic(R<0)of the port the overall impedance amplifies the internal resonance source at reactance zero-crossing frequency.The simplified stability criterion for DC cascade systems can be concluded as:in the negative damping frequency ranges(R<0),there exists no zero-crossing point of the reactance component(i.e.,X=0).According to the proposed stability criterion,the oscillation modes of cascade systems are classified.A typical one is the internal impedance instability excited by the negative damping,and the other one is that the external disturbance amplified by negativity in a low stability margin.Thus,the impedance reshaping method for stability improvement of the system can be further specified.The validity of the simplified criterion is verified theoretically and experimentally by a positive damping reshaping method.展开更多
Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC sub-grids.However,the variety of control modes and flexible bidirectional power flow complicate th...Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC sub-grids.However,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system reliability.This study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence network.Second,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation condition.Current amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus voltage.Compared with conventional methods,potential current limit failure and distortions under asymmetric faults can also be avoided.Finally,experiments verify feasibility of the proposed method.展开更多
An islanded microgrid exhibits poor transient power sharing between synchronous generators(SGs)and inverterinterfaced distributed generators(IIDGs).This large error of transient power-sharing may result in the overloa...An islanded microgrid exhibits poor transient power sharing between synchronous generators(SGs)and inverterinterfaced distributed generators(IIDGs).This large error of transient power-sharing may result in the overload of generators and a large deviation in frequency.In this paper,the mechanism that leads to poor transient power sharing is revealed.Then,a parameter design and a coordinated control strategy are proposed to improve transient power sharing.A coordinated enhanced power-sharing(EPS)control strategy is proposed for IIDGs,which prevents the overload of IIDGs in grid-forming mode and is compatible with the existing power sharing strategies.By using a hierarchical control structure,accurate transient power sharing is achieved without the knowledge of connecting impedance.The analysis results and the proposed control method are validated by simulation.展开更多
文摘BACKGROUND Gastric phytobezoars(GPBs)are very common in northern China.Combined therapy involving carbonated beverage consumption and endoscopic lithotripsy has been shown to be effective and safe.Existing studies on this subject are often case reports highlighting the successful dissolution of phytobezoars through Coca-Cola consumption.Consequently,large-scale prospective investigations in this domain remain scarce.Therefore,we conducted a randomized controlled trial to examine the effects of Coca-Cola consumption on GPBs.AIM To evaluate the impact of Coca-Cola on GPBs,including the dissolution rate,medical expenses,ulcer rate,and operation time.METHODS A total of 160 consecutive patients diagnosed with GPBs were allocated into two groups(a control group and an intervention group)through computer-generated randomization.Patients in the intervention group received a Coca-Cola-based regimen(Coca-Cola 2000-4000 mL per day for 7 d),while those in the control group underwent emergency fragmentation.RESULTS Complete dissolution of GPBs was achieved in 100% of the patients in the intervention group.The disparity in expenses between the control group and intervention group(t=25.791,P=0.000)was statistically significant,and the difference in gastric ulcer occurrence between the control group and intervention group(χ^(2)=6.181,P=0.013)was also statistically significant.CONCLUSION Timely ingestion of Coca-Cola yields significant benefits,including a complete dissolution rate of 100%,a low incidence of gastric ulcers,no need for fragmentation and reduced expenses.
文摘目的探讨牛鼻子引流(nose ring drain,NRD)技术结合Ilizarov环形外固定一期治疗GustiloⅢA型Pilon骨折的疗效。方法2017年3月—2019年12月,收治GustiloⅢA型Pilon骨折患者17例。其中男11例,女6例;年龄24~63岁,平均38.2岁。交通事故伤3例,高处坠落伤13例,贯通伤1例。急诊入院13例,骨折手术治疗后创面感染4例。合并腓骨骨折2例、外踝骨折3例。采用NRD技术结合Ilizarov环形外固定一期治疗。结果患者均获随访,随访时间8~12个月,平均9.9个月。创面均Ⅰ期愈合,4例术前感染患者随访期间无复发。17例患者术后3~7个月(平均4.5个月)骨折愈合后拆除外固定物。末次随访时,踝关节Kofoe评分中疼痛评分40~50分,平均44分;功能评分17~27分,平均25分;活动度评分8~18分,平均14分;获优8例,良7例,可1例,差1例。结论NRD技术结合Ilizarov环形外固定一期治疗GustiloⅢA型Pilon骨折,骨折固定及引流效果良好,大大降低了传统治疗方案并发症发生风险,减少了手术次数。
文摘We present a series of results acquired at a 2-kilometer distance using our lidar system under several weather conditions, clear, cloudy, light rain, moderately foggy, and night. The experimental results show that ghost imaging lidar via spar-sity constraints can realize imaging in all these weather conditions.
基金supported by the National Natural Science Foundation of China (No.51279115)
文摘Water temperature not only affects the solubility of gas in water but can also be an important factor in the dissipation process of supersaturated total dissolved gas （TDG）. The quantitative relationship between the dissipation process and temperature has not been previously described. This relationship affects the accurate evaluation of the dissipation process and the subsequent biological effects. This article experimentally investigates the impact of temperature on supersaturated TDG dissipation in static and turbulent conditions. The results show that the supersaturated TDG dissipation coefficient increases with the temperature and turbulence intensity. The quantitative relationship was verified by straight flume experiments. This study enhances our understanding of the dissipation of supersaturated TDG. Furthermore, it provides a scientific foundation for the accurate prediction of the dissipation process of supersaturated TDG in the downstream area and the negative imp）acts of high dam projects on aquatic ecosystems.
基金supported by the National Natural Science Foundation of China(Grant No.U2040209)the Open Funds of the Key Laboratory of Ocean Space Resource Management Technology of Ministry of Natural Resources(Grant No.KF-2021-108)the Fundamental Research Funds for the Central Universities(Grant No.B210204001).
文摘As major contributor to the blue carbon sink,intertidal zones play a crucial role in the global carbon cycle.In recent years,more attention has been given to the carbon cycle in intertidal wetlands.However,due to highly variable and uncertain environmental conditions,it is difficult to clarify the quantitative relationship between soil respiration and environmental factors through in-situ experiments.In this study,the response of soil respiration characteristics to variations in the temperature and water table was investigated using a monitoring apparatus of CO_(2)flux at the soil-air interface in the intertidal zone.The results showed that soil respiration flux was significantly correlated with temperature,and the correlation best fitted the DoseResp function.Meanwhile,the respiration flux was enhanced with the descent of water table,a relationship could be described by a quadratic function.The effect of the water table on soil respiration became more pronounced with the rise of temperature.These results provide significant clarification of the impact of human activities on the carbon cycle in bare intertidal zones and as well as support for numerical simulations of the carbon cycle in bare intertidal zones.
基金National Natural Science Foundation of China(62201165,62475270,62471147)National Key Research and Development Program of China(2024YFF0505601,2024YFF0505602,2024YFF0505600).
文摘Super-resolution(SR)imaging has been widely used in several fields like remote sensing and microscopy.However,it is challenging for existing SR approaches to capture SR images in a single shot,especially in dynamic imaging scenarios.
基金The authors are grateful to the National Natural Science Foundation of China(No.52373246)the Fundamental Research Program of Shanxi Provinces(No.20210302123128)the National Key Research and Development Program of China(No.2022YFA1404201)for financial support.
文摘Inorganic perovskitenanostructures have attracted considerable attention for their tunable band gaps and excellent optoelectronic properties.It is inevitable that phase segregation of halide perovskite usually occurs in mixed-halide perovskites under a focused laser llumination,which caused by photo-induced halide-ion segregation.Here,we reported an uniform perovskite alloy nanowires via a chemical vapor deposition(CvD)method.Microstructural characterization reveals that these perovskite nanowires have independent linear morphology_with high-quality crystalline.Micro-photoluminescence(PL)spectra exhibit that these nanowire structures show a dual-wavelength emissions at 690 and 570 nm,respectively.Additionally,time-dependent PL intensity of the emission peak at 690 nm increased by the decrease of the emission peak at 570 nm under a focused laser llumination,indicating the formation of phase segregation at the excited positions.Moreover,based on these as-grown halide perovskite CsPbBr2.52lo.48 nanowires,a reasonably optical switch is designed and constructed.This optical switch may have potential applications in timed blasting system and time-delay circuit in the future.
基金the National Natural Science Foundation of China(Nos.52373246,62127817,and U23A20380)the National Key Research and Development Program of China(No.2022YFA1404201)+2 种基金Science and Technology Major Special Project of Shanxi Province(No.202201010101005)the Shanxi Province Graduate Innovation Project(No.RC2400005577)the Shanxi Basic Research Program Project(No.20210302123128)for financial support.
文摘Bandgap engineering of semiconductor nanowires or nanoribbons(NRs)offers a promising material foundation for multifunctional integrated optoelectronic devices and circuits.Among these materials,all-inorganic halide perovskites have emerged as a leading candidate for next-generation photoelectronic applications due to their outstanding optoelectronic properties.In this work,we report the direct synthesis of high-quality bandgap gradient lead halide perovskite(CsPbCl_(3−3x)Br_(3x)and CsPbBr_(3−3x)I_(3x)(x=0-1))NRs using a magnetic-pulling source-moving chemical-vapor-deposition(CVD)method.Microstructural characterizations reveal that these as-grown NRs possess high-quality single crystalline structures with continuously tunable compositions.The photoluminescence emissions of these perovskite NRs can be finely tuned across the entire visible spectrum(417-702 nm).Furthermore,photodetectors based on these perovskite NRs demonstrate exceptional photoelectric performance,including a high I_(ON)/I_(OFF)ratio(10^(4)),superior responsivity(37.5 A/W),and remarkable detectivity(2.81×10^(13)Jones).A spatially resolved imaging sensor based on these perovskite NRs is also demonstrated,indicating promising applications in photoelectronic imaging circuits.These bandgap-tunable perovskite NRs provide a versatile materials platform for future integrated devices in electronics and optoelectronics.
文摘根据国际电信联盟关于IMT-2030愿景,第6代移动通信系统(the 6th generation mobile networks,6G)的覆盖服务需求将从单场景覆盖向多场景覆盖扩展,6G基础设施的部署也将逐步从2D覆盖向3D覆盖扩展、从局部覆盖向全球覆盖扩展、从中低频段融合使用向更高频段按需开启.上述需求使得6G在提升容量的同时,需要进一步考虑无线覆盖扩展需求.本文针对如何在6G网络结构时空尺度跨度大、全场景业务需求差异大、超密集覆盖能耗大等关键挑战下实现容量和能效约束下的覆盖能力扩展这一重大科学问题,首先提出了面向6G无线覆盖扩展的智能柔性组网架构;其次研究了面向6G无线覆盖扩展的关键技术,包括面向6G广域覆盖的多维立体空天地覆盖扩展技术、面向深度覆盖的超密集异构覆盖扩展技术和面向6G平滑度覆盖的超高速移动覆盖扩展技术;接着分析了基于语义通信的覆盖扩展技术;最后给出了6G全场景无线覆盖扩展仿真验证,通过定义6G无线覆盖扩展技术指标体系,进行了典型场景的覆盖性能仿真验证.
基金funded by grants from the National Key Research and Development Program of China(2022YFC2503300 and 2018YFA0800300)the National Natural Science Foundation of China(32030053 and 32241017)+3 种基金the startup fund from City University of Hong Kong(9380154)the RGC Theme-based Research Scheme(8770011)the TBSC Project fund,and Shenzhen Medical Research Fund(B2302042)R.T.was supported by the VA Research Service(I01 BX005927)and NIH(PAG007996).
文摘Dyslipidemia affects approximately half of all people with gout,and prior Mendelian randomization analysis suggested a causal role for elevated triglycerides in hyperuricemia(HU),but the underlying mechanisms remain elusive.We hypothesize that dyslipi-demia promotes hepatic urate biosynthesis in HU and gout and fatty acid(FA)oxidation(FAO)drives this process.Here we devel-oped a targeted metabolomics to quantify major metabolites in purine metabolic pathway in the sera of a human cohort with HU,gout,and normaluricemic controls.We found that the levels of major purine metabolites and multiple FAs were significantly elevated in HU and gout groups compared to normouricemic controls,whereas hypoxathine showed opposite trend.Furthermore,the levels of multiple serum FAs were positively correlated with urate,xanthine,and inosine but negatively with hypoxanthine,which was also observed in a murine model of high-fat diet-induced HU.Using a stable isotope-labeled metabolic flux assay,we discovered that exogenous hypoxanthine plays a key role in urate synthesis.Moreover,FAO-induced hypoxia-inducible factor 1 alpha(HIF-1α)activation upregulated 5ʹ-nucleotidase II(NT5C2)and xanthine dehydrogenase(XDH)levels to facilitate hypox-anthine uptake from the blood to the liver and activation of urate biosynthesis.Our findings were further supported by data in human hepatocytes and 50 paired serum and liver tissues from liver transplant donors.Together,this study uncovers a mecha-nism by which FAO promotes hepatic urate synthesis by activating HIF-1α-NT5C2/XDH pathways,directly linking lipid metabo-lism to HU.
基金supported by National Key Research and Development Program of China(2018YFB0904100)Science and Technology Project of SGCC(SGHB0000KXJS1800685).
文摘In DC distributed power systems(DPSs),the complex impedance interactions possibly lead to DC bus voltage oscillation or collapse.In previous research,the stability analysis of DPSs is implemented based on mathematical analysis in control theory.The specific mechanisms of the instability of the cascade system have not been intuitively clarified.In this paper,the stability analysis of DPSs based on the traditional Nyquist criterion is simplified to the resonance analysis of the seriesconnected port impedance(Z=R+jX)of source and load converters.It reveals that the essential reason for impedance instability of a DC cascade system is that the negative damping characteristic(R<0)of the port the overall impedance amplifies the internal resonance source at reactance zero-crossing frequency.The simplified stability criterion for DC cascade systems can be concluded as:in the negative damping frequency ranges(R<0),there exists no zero-crossing point of the reactance component(i.e.,X=0).According to the proposed stability criterion,the oscillation modes of cascade systems are classified.A typical one is the internal impedance instability excited by the negative damping,and the other one is that the external disturbance amplified by negativity in a low stability margin.Thus,the impedance reshaping method for stability improvement of the system can be further specified.The validity of the simplified criterion is verified theoretically and experimentally by a positive damping reshaping method.
文摘Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC sub-grids.However,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system reliability.This study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence network.Second,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation condition.Current amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus voltage.Compared with conventional methods,potential current limit failure and distortions under asymmetric faults can also be avoided.Finally,experiments verify feasibility of the proposed method.
基金supported in part by National Natural Science Foundation of China under Grant 52125705in part by National Natural Science Foundation of China under Grant 52107194.
文摘An islanded microgrid exhibits poor transient power sharing between synchronous generators(SGs)and inverterinterfaced distributed generators(IIDGs).This large error of transient power-sharing may result in the overload of generators and a large deviation in frequency.In this paper,the mechanism that leads to poor transient power sharing is revealed.Then,a parameter design and a coordinated control strategy are proposed to improve transient power sharing.A coordinated enhanced power-sharing(EPS)control strategy is proposed for IIDGs,which prevents the overload of IIDGs in grid-forming mode and is compatible with the existing power sharing strategies.By using a hierarchical control structure,accurate transient power sharing is achieved without the knowledge of connecting impedance.The analysis results and the proposed control method are validated by simulation.
