1 EXTREME DROUGHT AND HYDROGEODESY TECHNOLOGIES The World Meteorological Organization has officially declared 2023 as the hottest year on record,with the average global temperature surpassing pre-industrial(1850-1900)...1 EXTREME DROUGHT AND HYDROGEODESY TECHNOLOGIES The World Meteorological Organization has officially declared 2023 as the hottest year on record,with the average global temperature surpassing pre-industrial(1850-1900)average by 1.45℃.While temperature is not the only climate observable from the complex processes for the geneses of droughts,recent hottest years have witnessed numerous instances of extreme droughts.展开更多
The first total synthesis of marine sesquiterpene(hydro)quinone meroterpenoids dysideanones A and E–G(1 and 4–6)has been accomplished in an enantioselective and divergent way.The sesquiterpene fragment and the aroma...The first total synthesis of marine sesquiterpene(hydro)quinone meroterpenoids dysideanones A and E–G(1 and 4–6)has been accomplished in an enantioselective and divergent way.The sesquiterpene fragment and the aromatic moiety were efficiently connected via a site-selective and diastereoselective intermolecular alkylation of Wieland–Miescher ketone derivative 9 and benzyl bromide 10.The core 6/6/6/6-fused backbone of dysideanones was efficiently constructed through an intramolecular radical cyclization reaction.Dysideanone G(6)was easily prepared on a gram-scale and dysideanones A,E,and F(1,4,and 5)were divergently transformed from dysideanone G(6)in one or two steps.展开更多
Background: Wrist pain is prevalent. Activities such as dexterous sports, prolonged use of personal handheld devices, and extensive desktop keyboard usage are common contributors to wrist pain. Intersection syndrome, ...Background: Wrist pain is prevalent. Activities such as dexterous sports, prolonged use of personal handheld devices, and extensive desktop keyboard usage are common contributors to wrist pain. Intersection syndrome, a form of inflammatory tenosynovitis, occurs at the intersection of the first and second dorsal compartments of the wrist. The first dorsal compartment is comprised of the tendons of abductor pollicis longus and extensor pollicis brevis, while the second dorsal compartment contains the tendons of extensor carpi radialis longus and extensor carpi radialis brevis. Intersection syndrome is diagnosed by pain localized to the dorsoradial forearm, approximately five cm proximal to the wrist joint, which worsens with resisted wrist and thumb extension. To date, the use of hydro dissection with 5% dextrose under ultrasound guidance as a treatment for Intersection syndrome has not been reported. This case report presents the first report on ultrasound-guided hydro dissection as a therapeutic approach for intersection syndrome. Methods: A case report, with informed consent, involving a 32-year-old male athlete. The patient, a hurling player, presented with chronic right wrist pain diagnosed as intersection syndrome. The condition significantly affected his work, sporting activities, and daily living activities. Previous conservative management and physiotherapy had failed to alleviate his symptoms. To confirm the diagnosis, relevant imaging was performed, supplemented by dynamic ultrasound assessment. The procedure was performed aseptically. Continuous ultrasound guidance was employed to ensure accurate needle placement. Once the needle tip position was confirmed, an initial injection of 5 mL of 0.25% chirocaine was administered. 10 mL of 5% dextrose was injected under ultrasound guidance for hydro dissection, with good visualization of the solution’s distribution. Conclusion: Ultrasound-guided hydro dissection has not previously been documented as a treatment option for intersection syndrome. In this case, it proved to be an effective pain-relieving therapy with sustained effect at three-month clinical follow-up. Further studies are required.展开更多
Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runne...Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runner rim,increasing tip clearance and triggering leakage flow and cavitation.These effects reduce hydraulic efficiency and accelerate blade surface erosion,posing serious risks to unit safety and operational stability.This study investigates the influence of tip clearance on cavitation performance in a 24 MW prototype bulb turbine.A three-dimensional numericalmodel is developed to simulate various operating conditions with different tip clearance values(3.0,4.5,and 6.0 mm)and cavitation numbers(σ=1.20–1.33).Internal flow characteristics—including pressure distribution,velocity fields,hydraulic efficiency,and pressure pulsation—are analyzed to elucidate the impact of tip clearance on cavitation development.Results show that underσ=1.2 and a 4.5 mm tip clearance,the pressure pulsation amplitude at the blade tip reaches 4870 Pa—approximately 1.5 times higher than that near the hub.At partial flowconditions,turbine efficiency decreases by up to 6.8%compared to the rated condition.Increasing the tip clearance from 1.5 to 6.0 mm expands the low-pressure area near the blade tip by around 32%,significantly intensifying cavitation.Frequency domain analysis reveals dominant pulsation frequencies between 10–20Hz,characterized by blade-passing features and a wave-clipping effect.These findings provide theoretical insight and quantitative evidence to support the optimization of tip clearance design and cavitation mitigation strategies in bulb turbines,aiming to improve both efficiency and operational stability.展开更多
Aim To determine efficiency of multi-range hydro-mechanical stepless transmis- sion(HMT).Methods Ageneral model of HMT was of HMT was structured.On the basis of power flow analysis, the efficiency was obtained,Results...Aim To determine efficiency of multi-range hydro-mechanical stepless transmis- sion(HMT).Methods Ageneral model of HMT was of HMT was structured.On the basis of power flow analysis, the efficiency was obtained,Results efficiency of multi-range HMT changes continuously with output speed in speed range and is higher than the highest point of the hydraulic efficiency,The volumetric efficiency can potentially result in the speed fluctuation, which can be reduced or eliminated through controlling the ratio of the displacements ofhydraulic unity properly or changing the point of range exchanging .And the mechanical- constant output torque or different output torque under the condition of constant pressure when the transmission works in different parts of a range,Conclusion The multi-range HMT is an ideal stepless transmission with high efficiency.展开更多
基金funded by the National Natural Science Fund of China(Nos.42442015,42274111)。
文摘1 EXTREME DROUGHT AND HYDROGEODESY TECHNOLOGIES The World Meteorological Organization has officially declared 2023 as the hottest year on record,with the average global temperature surpassing pre-industrial(1850-1900)average by 1.45℃.While temperature is not the only climate observable from the complex processes for the geneses of droughts,recent hottest years have witnessed numerous instances of extreme droughts.
基金Financial support for this work was provided by the National Natural Science Foundation of China(Nos.22171146,21971121,and 22188101)the Fundamental Research Funds for the Central Universities,Nankai University(No.63231199)the State Key Laboratory of Medicinal Chemical Biology。
文摘The first total synthesis of marine sesquiterpene(hydro)quinone meroterpenoids dysideanones A and E–G(1 and 4–6)has been accomplished in an enantioselective and divergent way.The sesquiterpene fragment and the aromatic moiety were efficiently connected via a site-selective and diastereoselective intermolecular alkylation of Wieland–Miescher ketone derivative 9 and benzyl bromide 10.The core 6/6/6/6-fused backbone of dysideanones was efficiently constructed through an intramolecular radical cyclization reaction.Dysideanone G(6)was easily prepared on a gram-scale and dysideanones A,E,and F(1,4,and 5)were divergently transformed from dysideanone G(6)in one or two steps.
文摘Background: Wrist pain is prevalent. Activities such as dexterous sports, prolonged use of personal handheld devices, and extensive desktop keyboard usage are common contributors to wrist pain. Intersection syndrome, a form of inflammatory tenosynovitis, occurs at the intersection of the first and second dorsal compartments of the wrist. The first dorsal compartment is comprised of the tendons of abductor pollicis longus and extensor pollicis brevis, while the second dorsal compartment contains the tendons of extensor carpi radialis longus and extensor carpi radialis brevis. Intersection syndrome is diagnosed by pain localized to the dorsoradial forearm, approximately five cm proximal to the wrist joint, which worsens with resisted wrist and thumb extension. To date, the use of hydro dissection with 5% dextrose under ultrasound guidance as a treatment for Intersection syndrome has not been reported. This case report presents the first report on ultrasound-guided hydro dissection as a therapeutic approach for intersection syndrome. Methods: A case report, with informed consent, involving a 32-year-old male athlete. The patient, a hurling player, presented with chronic right wrist pain diagnosed as intersection syndrome. The condition significantly affected his work, sporting activities, and daily living activities. Previous conservative management and physiotherapy had failed to alleviate his symptoms. To confirm the diagnosis, relevant imaging was performed, supplemented by dynamic ultrasound assessment. The procedure was performed aseptically. Continuous ultrasound guidance was employed to ensure accurate needle placement. Once the needle tip position was confirmed, an initial injection of 5 mL of 0.25% chirocaine was administered. 10 mL of 5% dextrose was injected under ultrasound guidance for hydro dissection, with good visualization of the solution’s distribution. Conclusion: Ultrasound-guided hydro dissection has not previously been documented as a treatment option for intersection syndrome. In this case, it proved to be an effective pain-relieving therapy with sustained effect at three-month clinical follow-up. Further studies are required.
基金Funded by the National Natural Science Foundation of China(52066011)Jiuquan Science and Technology Plan Project University-Level Key Project(2024XJKXM03)Foundation of Key Laboratory of Solar Power System(Grant No.2024SPKL03).
文摘Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runner rim,increasing tip clearance and triggering leakage flow and cavitation.These effects reduce hydraulic efficiency and accelerate blade surface erosion,posing serious risks to unit safety and operational stability.This study investigates the influence of tip clearance on cavitation performance in a 24 MW prototype bulb turbine.A three-dimensional numericalmodel is developed to simulate various operating conditions with different tip clearance values(3.0,4.5,and 6.0 mm)and cavitation numbers(σ=1.20–1.33).Internal flow characteristics—including pressure distribution,velocity fields,hydraulic efficiency,and pressure pulsation—are analyzed to elucidate the impact of tip clearance on cavitation development.Results show that underσ=1.2 and a 4.5 mm tip clearance,the pressure pulsation amplitude at the blade tip reaches 4870 Pa—approximately 1.5 times higher than that near the hub.At partial flowconditions,turbine efficiency decreases by up to 6.8%compared to the rated condition.Increasing the tip clearance from 1.5 to 6.0 mm expands the low-pressure area near the blade tip by around 32%,significantly intensifying cavitation.Frequency domain analysis reveals dominant pulsation frequencies between 10–20Hz,characterized by blade-passing features and a wave-clipping effect.These findings provide theoretical insight and quantitative evidence to support the optimization of tip clearance design and cavitation mitigation strategies in bulb turbines,aiming to improve both efficiency and operational stability.
文摘Aim To determine efficiency of multi-range hydro-mechanical stepless transmis- sion(HMT).Methods Ageneral model of HMT was of HMT was structured.On the basis of power flow analysis, the efficiency was obtained,Results efficiency of multi-range HMT changes continuously with output speed in speed range and is higher than the highest point of the hydraulic efficiency,The volumetric efficiency can potentially result in the speed fluctuation, which can be reduced or eliminated through controlling the ratio of the displacements ofhydraulic unity properly or changing the point of range exchanging .And the mechanical- constant output torque or different output torque under the condition of constant pressure when the transmission works in different parts of a range,Conclusion The multi-range HMT is an ideal stepless transmission with high efficiency.
