Multiple gravity assists(MGAs) have become an enabling technology for modern deep space exploration, significantly extending mission reach while minimizing propellant consumption. This paper presents a comprehensive r...Multiple gravity assists(MGAs) have become an enabling technology for modern deep space exploration, significantly extending mission reach while minimizing propellant consumption. This paper presents a comprehensive review of MGAbased trajectory design methodologies employed in deep space missions. A systematic classification framework is established, categorizing MGAs techniques into three fundamental domains based on their underlying dynamical mechanisms:(1) escape and capture orbit techniques,(2) diverse transfer trajectory designs, and(3) orbit adjustment and directional control strategies. Our analysis in each category connects representative methods to their real-world applications and missions. Finally, future research prospects are outlined, aiming to ultimately support the development of advanced MGA-based trajectory planning for deep space missions.展开更多
Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with ...Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.展开更多
BACKGROUND:Hemiplegia,a prevalent stroke-related condition,is often studied for motor dysfunction;however,spasticity remains under-researched.Abnormal muscle tone significantly hinders hemiplegic patients’walking rec...BACKGROUND:Hemiplegia,a prevalent stroke-related condition,is often studied for motor dysfunction;however,spasticity remains under-researched.Abnormal muscle tone significantly hinders hemiplegic patients’walking recovery.OBJECTIVE:To determine whether early suspension-protected training with a personal assistant machine for stroke patients enhances walking ability and prevents muscle spasms.METHODS:Thirty-two early-stage stroke patients from Shenzhen University General Hospital and the China Rehabilitation Research Center were randomly assigned to the experimental group(n=16)and the control group(n=16).Both groups underwent 4 weeks of gait training under the suspension protection system for 30 minutes daily,5 days a week.The experimental group used the personal assistant machine during training.Three-dimensional gait analysis(using the Cortex motion capture system),Brunnstrom staging,Fugl-Meyer Assessment for lower limb motor function,Fugl-Meyer balance function,and the modified Ashworth Scale were evaluated within 1 week before the intervention and after 4 weeks of intervention.RESULTS AND CONCLUSION:After the 4-week intervention,all outcome measures showed significant changes in each group.The experimental group had a small but significant increase in the modified Ashworth Scale score(P<0.05,d=|0.15|),while the control group had a large significant increase(P<0.05,d=|1.48|).The experimental group demonstrated greater improvements in walking speed(16.5 to 38.44 cm/s,P<0.05,d=|4.01|),step frequency(46.44 to 64.94 steps/min,P<0.05,d=|2.32|),stride length(15.50 to 29.81 cm,P<0.05,d=|3.44|),and peak hip and knee flexion(d=|1.82|to|2.17|).After treatment,the experimental group showed significantly greater improvements than the control group in walking speed(38.44 vs.26.63 cm/s,P<0.05,d=|2.75|),stride length,peak hip and knee flexion(d=|1.31|to|1.45|),step frequency(64.94 vs.59.38 steps/min,P<0.05,d=|0.85|),and a reduced support phase(bilateral:24.31%vs.28.38%,P<0.05,d=|0.88|;non-paretic:66.19%vs.70.13%,P<0.05,d=|0.94|).For early hemiplegia,personal assistant machine-assisted gait training under the suspension protection system helps establish a correct gait pattern,prevents muscle spasms,and improves motor function.展开更多
Hebei Province has incorporated targeted assistance services for people with disabilities into livelihood projects,upgrading the quality and efficiency of support services for disadvantaged groups.THE living and nursi...Hebei Province has incorporated targeted assistance services for people with disabilities into livelihood projects,upgrading the quality and efficiency of support services for disadvantaged groups.THE living and nursing allowances provided by the Chinese government for people with disabilities who are unable to work are not only important components of China’s social security system which provide for the needs of its disabled,but also show China’s ability to guarantee the basic living standard and social fairness and justice for this group of people.展开更多
Objective:To identify predictors of pregnancy and live birth outcomes in assisted reproductive technology(ART)cycles based on patient characteristics,hormonal profile,and embryo transfer variables.Methods:This retrosp...Objective:To identify predictors of pregnancy and live birth outcomes in assisted reproductive technology(ART)cycles based on patient characteristics,hormonal profile,and embryo transfer variables.Methods:This retrospective cohort study included 50 fresh in vitro fertilization(IVF)/intracytoplasmic sperm injection(ICSI)cycles selected from ART participants at a single tertiary ART center.Controlled ovarian stimulation was performed using recombinant follicle stimulating hormone(rFSH),gonadotropin-releasing hormone(GnRH)antagonist,and menotropins;oocyte retrieval occurred 36 h after trigger and embryo transfer was performed on day 3 or 5.Outcomes(chemical pregnancy,ongoing pregnancy,abortion,live birth)were compared across groups stratified by maternal age,antral follicle count(AFC),anti-Müllerian hormone(AMH),baseline luteinizing hormone(LH),estradiol(E2)at trigger,and endometrial thickness.Multivariate regression was used to identify independent predictors of live birth.Results:A total of 124 ART patients were screened during the study period,of whom 50 participants meeting the eligibility criteria were included in the final analysis.The median age of the participants was 35.8 years[interquartile range(IQR)32.5–39.6].The median AFC was 8(IQR 4–14),AMH level was 1.4 ng/mL(IQR 0.7–2.9),and the median endometrial thickness at embryo transfer was 10.2 mm(IQR 9.0–11.3).Chemical,ongoing,abortion,and live birth rates were 62%,32%,12%,and 16%,respectively.Younger maternal age(<35 years),higher AFC(>12),AMH 1–4 ng/mL,and endometrial thickness≥10 mm were associated with more favorable pregnancy outcomes.In multivariate analysis,higher baseline LH(β=0.089;95%CI 0.017–0.162;P=0.02)and greater endometrial thickness(β=0.145;95%CI 0.011–0.278;P=0.04)independently predicted live birth,whereas age,AFC,AMH,and E2 did not.Conclusions:Maternal age,ovarian reserve markers,LH levels,and endometrial thickness collectively influence ART outcomes.Baseline LH and endometrial receptivity are key independent predictors of live birth and may guide individualized treatment strategies.展开更多
Self-suspended proppants,which enable clear-water fracturing,represent a promising new class of materials for reservoir stimulation.Given the economic limitations associated with their exclusive use,this study investi...Self-suspended proppants,which enable clear-water fracturing,represent a promising new class of materials for reservoir stimulation.Given the economic limitations associated with their exclusive use,this study investigates proppant transport behavior in hybrid systems combining self-suspended proppants with conventional 40/70 mesh quartz sand at various mixing ratios.A dedicated experimental apparatus was developed to replicate field-relevant complex fracture networks,consisting of a main fracture and two branching fractures with different deflection angles.Using this system,sand bank formation and proppant distribution were examined for both conventional quartz sand fracturing and fracturing augmented with self-suspended proppants.The effects of slurry discharge volume,proppant mixing ratio,sand ratio,and injection location of the self-suspended proppant on transport and placement behavior were systematically analyzed.According to the results,the incorporation of self-suspended proppants markedly enhances the proppant-carrying capacity of the slurry and substantially modifies sand bank morphology.Increasing the discharge volume raises the inlet slope angle and promotes greater proppant penetration into branch fractures.The proportion of self-suspended proppant governs slurry viscoelasticity and,consequently,proppant settling behavior.As the fraction of self-suspended proppant decreases,the equilibrium height of the sand bank increases,while the proppant mass fraction within branch fractures exhibits a non-monotonic response,initially decreasing and then increasing.Variations in sand ratio alter both overall proppant concentration and the self-suspended proppant-to-water ratio,thereby modulating slurry rheology and influencing proppant placement.In addition,changes in injection location affect near-wellbore vortex structures,leading to distinct sand bank morphologies.展开更多
Twinning-induced plasticity(TWIP)steel was processed using electrically assisted friction stir welding(EFSW).The microstructure,mechanical properties,and deformation behavior of the welded joints were systematically i...Twinning-induced plasticity(TWIP)steel was processed using electrically assisted friction stir welding(EFSW).The microstructure,mechanical properties,and deformation behavior of the welded joints were systematically investigated.The results show that the average grain size was refined from 3.67μm in the base material(BM)to 1.39μm in the stir zone(SZ),while it increased to 4.19μm in the heat-affected zone(HAZ).The fraction of twin boundaries(TBs)decreased from 20.7%in the BM to 6.9%in the SZ and increased to24.5%in the HAZ.The ultimate tensile strength,yield strength,and elongation of the BM were 1021 MPa,505 MPa,and 65.8%,respectively.In comparison,the EFSW joint exhibited values of 1055 MPa,561 MPa,and 60.8%,corresponding to 103.3%,111.1%,and 92.4%of those of the BM,respectively.During tensile testing,plastic deformation was primarily concentrated in the BM,although both the SZ and HAZ also exhibited notable plastic deformation.Fracture ultimately occurred in the BM.展开更多
Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is p...Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.展开更多
Dear Editor,We present this case report which discusses a patient who underwent flap amputation after repeated attempts to resolve persistent and severe epithelial ingrowth following laser-assisted in situ keratomileu...Dear Editor,We present this case report which discusses a patient who underwent flap amputation after repeated attempts to resolve persistent and severe epithelial ingrowth following laser-assisted in situ keratomileusis(LASIK)surgery.Epithelial ingrowth is a known complication of LASIK surgery,typically manageable with minimal measures.However,severe cases may necessitate more aggressive interventions,such as flap amputation[1].LASIK is a widely performed refractive surgery with high success rates and excellent visual outcome[2].展开更多
Objective:To investigate the impact of anti-Müllerian hormone(AMH)levels on the outcomes of intracytoplasmic sperm injection(ICSI)cycles in women of advanced age and also to explore the effect of age on the ICSI ...Objective:To investigate the impact of anti-Müllerian hormone(AMH)levels on the outcomes of intracytoplasmic sperm injection(ICSI)cycles in women of advanced age and also to explore the effect of age on the ICSI results in patients with low AMH levels.Methods:This retrospective cohort study involved 143 infertile couples undergoing ICSI cycles at a fertility clinic in Iran from November 2021 to November 2023.Women aged<37 years with AMH<1 ng/mL and those aged≥37 years were included.A standardized ovarian stimulation protocol was followed,leading to oocyte retrieval and ICSI on mature oocytes.Key oocyte quality indexes,including the maturation rate,fertilization rate,and embryo quality metrics,were evaluated.Poisson regression analyses were also employed to investigate the association between AMH levels and oocyte quality parameters in the advanced age groups,as well as the association between age and oocyte quality parameters in patients with low AMH.Results:We analyzed 143 ICSI cycles from 143 infertile couples.The mean ages of the women and their partners were(38.2±4.7)years and(40.6±5.9)years,respectively,with a median(IQR)AMH level of 0.7(0.4–2.0)ng/mL.Younger women with low AMH levels(<1 ng/mL)showed significantly better outcomes in terms of the number of MⅡ oocytes[adjusted odds ratio(aOR)1.89,95%CI 1.31-2.71;P=0.001],fertilized(2PN)oocytes(aOR 1.97,95%CI 1.36-2.86;P<0.001),embryo number(aOR 2.16,95%CI 1.44-3.24;P<0.001),and embryos suitable for freezing(aOR 2.88,95%CI 1.80-4.61;P<0.001)compared to advanced-age women.Furthermore,among women of advanced age,those with normal AMH levels exhibited a significantly higher number of MⅡ oocyte(aOR 3.55,95%CI 2.31-5.44;P<0.001),fertilized(2PN)oocytes(aOR 3.54,95%CI 2.29-5.49;P<0.001),embryo number(aOR 3.89,95%CI 2.48-6.10;P<0.001),and embryos suitable for freezing(aOR 4.75,95%CI 2.79-8.09;P<0.001)compared to those with low AMH levels.Conclusions:AMH level is a significant predictor of oocyte and embryo number and quality in infertile women of advanced age undergoing ICSI cycles.Our findings suggest that maternal age markedly impacts the quality of oocytes and embryos in low AMHlevel patients.展开更多
The latest generation of aero engines has set higher standards for thrust-to-weight ratio and energy conversion efficiency,making it imperative to address the challenge of efficiently and accurately machining film coo...The latest generation of aero engines has set higher standards for thrust-to-weight ratio and energy conversion efficiency,making it imperative to address the challenge of efficiently and accurately machining film cooling holes.It has been demonstrated that conventional long-pulse lasers are incapable of meeting the elevated quality surface finish requirements for these holes,a consequence of the severe thermal defects.The employment of backside water-assisted laser drilling technology confers a number of distinct advantages in terms of mitigating laser thermal damage,thus representing a highly promising solution to this challenge.However,significant accumulation of bubbles and machining products during the backside water-assisted laser drilling process has been demonstrated to have a detrimental effect on laser transmission and machining stability,thereby reducing machining quality.In order to surmount these challenges,a novel method has been proposed,namely an ultrasonic shock water flow-assisted picosecond laser drilling technique.Numerical models for ultrasonic acoustic streaming and particle tracking for machining product transport have been established to investigate the mechanism.The simulation results demonstrated that the majority of the machining products could rapidly move away from the machining area because of the action of acoustic streaming,thereby avoiding the accumulation of bubbles and products.Subsequent analysis,comparing the process performance in micro-hole machining,confirmed that the ultrasonic field could effectively eliminate bubble and chip accumulation,thus significantly improving micro-hole quality.Furthermore,the impact of ultrasonic and laser parameters on micro-hole quality under varying machining methods was thoroughly investigated.The findings demonstrated that the novel methodology outlined in this study yielded superior-quality micro-holes at elevated ultrasonic and laser power levels,in conjunction with reduced laser frequency and scanning velocity.The taper of the micro-holes produced by the new method was reduced by more than 25%compared with the other conventional methods.展开更多
Based on the Bismuth-Corlette classification of hilar cholangiocarcinoma,the patients with types I,II,and III can undergo radical resection in the absence of extensive intrahepatic metastasis and vascular invasion[1]....Based on the Bismuth-Corlette classification of hilar cholangiocarcinoma,the patients with types I,II,and III can undergo radical resection in the absence of extensive intrahepatic metastasis and vascular invasion[1].Depending on the scope of tumor invasion in bile duct,a combined resection of parts of the liver,hepatic ducts,common bile ducts,regional lymph nodes,and even parts of the duodenum and pancreas is necessary,along with biliary and gastrointestinal reconstructions[2].The surgical plan is complex,involving a large resection area and significant trauma.In recent years,laparoscopic or robot assisted radical resection of hilar cholangiocarcinoma has been applied clinically[3,4].With the advanced laparoscopic equipment,many patients undergo hepatopancreatoduodenectomy successfully[5].The limitations of traditional laparoscopic techniques restrict their wide application in clinical practice.However,the Da Vinci robot has been widely applied due to its clear field of vision and flexible manipulation.However,its utilization in hepato-pancreatoduodenectomy for hilar cholangiocarcinoma is still relatively rare.Here,we report a case with hilar cholangiocarcinoma at clinical stage IIIb who underwent robot-assisted hepato-pancreatoduodenectomy.展开更多
Rationale:This case report describes a couple with recurrent fertilization failure despite undergoing multiple cycles of intracytoplasmic sperm injection(ICSI).The principal clinical concern was suspected oocyte activ...Rationale:This case report describes a couple with recurrent fertilization failure despite undergoing multiple cycles of intracytoplasmic sperm injection(ICSI).The principal clinical concern was suspected oocyte activation deficiency(OAD),in which fertilization is impeded due to the oocyte’s inability to initiate embryogenesis,commonly attributed to inadequate intracellular calcium(Ca^(2+))release following sperm injection.Patient concerns:The couple repeatedly experienced complete or near-complete fertilization failure in previous ICSI cycles,raising suspicion of an underlying oocyte activation defect.Diagnosis:Based on the repeated absence of fertilization post-ICSI and clinical history,a diagnosis of suspected OAD leading to recurrent ICSI fertilization failure was considered.Interventions:Artificial oocyte activation(AOA)using the calcium ionophore A23187 was performed.After ICSI,unfertilized oocytes were exposed to the ionophore to induce Ca^(2+)influx,simulating physiological calcium oscillations essential for oocyte activation.The efficacy of intervention was evaluated through subsequent embryonic development,morphological grading,and chromosomal integrity.Outcomes:Following AOA treatment,successful oocyte activation occurred,resulting in the formation of high-grade embryos with normal developmental progression.Chromosomal analysis revealed no detectable abnormalities,indicating genomic stability.Lessons:Calcium ionophore–mediated AOA may serve as an effective adjunct in cases of recurrent ICSI failure attributed to OAD.This case highlights the importance of individualized therapeutic strategies in assisted reproduction;however,further research is needed to refine protocols,validate broader clinical efficacy,and assess long-term safety,including potential epigenetic risks.展开更多
Dear Editor,This letter presents a model predictive control(MPC)scheme for human-robot interaction(HRI)in a multi-joint exoskeleton robot(ER)driven by series elastic actuator(SEA).The proposed scheme in robot-in-charg...Dear Editor,This letter presents a model predictive control(MPC)scheme for human-robot interaction(HRI)in a multi-joint exoskeleton robot(ER)driven by series elastic actuator(SEA).The proposed scheme in robot-in-charge(RIC)mode facilitates the ER driven by SEA to provide the required assistance and support for the subject.展开更多
Electroslag remelting(ESR) is an important metallurgical process for producing high-purity materials with homogeneous compositions and sound microstructures,and its typical products are ingots or simple castings.The c...Electroslag remelting(ESR) is an important metallurgical process for producing high-purity materials with homogeneous compositions and sound microstructures,and its typical products are ingots or simple castings.The core principle involves the resistive melting of a consumable electrode within a slag pool,followed by the refining of molten metal droplets as they traverse the slag,and subsequent sequential solidification in a water-cooled mold.However,conventional ESR processes face limitations in producing large or complex-shaped components,enhancing production efficiency,achieving highly specialized microstructures,and meeting ultra-high purity demands for advanced applications.Advanced composite ESR technologies have been developed to overcome these limitations by innovatively modifying key process aspects.For instance,electrode systems are improved using vibration,rotation,or multiple electrodes.Enhanced mold design and solidification control are achieved through techniques including conductive molds,mold rotation,and ingot withdrawal.Precise control of the process is realized through the use of protective gas,vacuum,or elevated pressure,as well as the application of external fields such as magnetic fields or ultrasonic vibration.This review comprehensively summarizes these advanced techniques,examining their principles and characteristics,and discussing their specific advantages and challenges.展开更多
erized by a periodic real-space modulation of the superconducting pairing order parameter,is a novel quantum phase observed in superconducting(SC)systems.It is believed to play a key role in understanding the pseudoga...erized by a periodic real-space modulation of the superconducting pairing order parameter,is a novel quantum phase observed in superconducting(SC)systems.It is believed to play a key role in understanding the pseudogap phase of superconductors and has recently been discovered in bulk cuprates,transition-metal dichalcogenide,and other unconventional superconductors.However,artificially engineered PDW in designable two-dimensional materials remain rare.In this paper,we report a strain-assisted strategy to realize cooper-pair density modulation in a van der Waals heterostructure:graphene on SC 2H-NbSe2.Superconductivity is induced in graphene via the proximity effect.Meanwhile,the graphene membrane spontaneously buckles into a periodic structure owing to strain,featuring a spatially modulated local density of states(LDOS).The interplay between the spatially modulated LDOS and the proximity-induced superconductivity results in an oscillatory pair density determined by the buckled geometry,constituting an artificial PDW.This approach enables the engineering of PDWs with periodicities of up to tens of nanometers and allows their realization in a variety of heterostructures with tailored designs.Our work provides new insights into the investigation of PDW physics using predesigned two-dimensional materials.展开更多
Genomic disorders affecting the central nervous system(CNS)are among the most complex and devastating conditions in human health.Moreover,these disorders,such as Rett syndrome,spinal muscular atrophy,and Fragile X syn...Genomic disorders affecting the central nervous system(CNS)are among the most complex and devastating conditions in human health.Moreover,these disorders,such as Rett syndrome,spinal muscular atrophy,and Fragile X syndrome,are typically caused by mutations in genes essential for neural development,synaptic function,or cellular homeostasis.Despite the genetic diversity involved,these diseases share key pathological features,including progressive neurodegeneration,disruption of neural circuits,and loss of cognitive or motor function.Meanwhile,one of the significant clinical challenges in treating CNS disorders is the limited regenerative capacity of the adult nervous system,which makes reversing disease progression extremely difficult once symptoms appear.In addition,the blood-brain barrier(BBB)restricts the passage of most systemically administered therapeutics,further complicating effective intervention.Consequently,current treatment options remain largely palliative,and effective cures remain elusive.展开更多
Cases of widespread bone hydatid infection are relatively rare in clinical practice.In this study,we reported for the first time a validated integrated repair therapy for multiple bone tissues,including the hip,femur,...Cases of widespread bone hydatid infection are relatively rare in clinical practice.In this study,we reported for the first time a validated integrated repair therapy for multiple bone tissues,including the hip,femur,and knee,caused by echinococ cosis.Artificial intelligence(AI)was used to develop a targeted surgical plan and to design a personalized prosthesis.Finite element analysis(FEA)was used to optimize the mechanical effectiveness of a customized integrated replacement prosthesis and to model stress distribution in the surrounding bone.Three-dimensional(3 D)printing was used to fabricate a customized prosthesis.With the assistance of AI,FEA,and 3 D printing technology,a personalized surgical plan and customized prosthesis were successfully constructed based on the patient’s disease.This approach achieved a successful therapeutic effect,demonstrating that AI-assisted personalized medicine holds great promise for the future.展开更多
Near-Earth asteroids have gained a lot of interest and the development in low-thrust propulsion technology makes complex deep space exploration missions possible. A mission from low-Earth orbit using low-thrust electr...Near-Earth asteroids have gained a lot of interest and the development in low-thrust propulsion technology makes complex deep space exploration missions possible. A mission from low-Earth orbit using low-thrust electric propulsion system to rendezvous with near-Earth asteroid and bring sample back is investigated. By dividing the mission into five segments, the complex mission is solved separately. Then different methods are used to find optimal trajectories for every segment. Multiple revolutions around the Earth and multiple Moon gravity assists are used to decrease the fuel consumption to escape from the Earth. To avoid possible numerical difficulty of indirect methods, a direct method to parameterize the switching moment and direction of thrust vector is proposed. To maximize the mass of sample, optimal control theory and homotopic approach are applied to find the optimal trajectory. Direct methods of finding proper time to brake the spacecraft using Moon gravity assist are also proposed. Practical techniques including both direct and indirect methods are investigated to optimize trajectories for different segments and they can be easily extended to other missions and more precise dynamic model.展开更多
基金supported in part by the National Natural Science Foundation of China (Grant Nos. 12322202, 12172013, and 12272116)。
文摘Multiple gravity assists(MGAs) have become an enabling technology for modern deep space exploration, significantly extending mission reach while minimizing propellant consumption. This paper presents a comprehensive review of MGAbased trajectory design methodologies employed in deep space missions. A systematic classification framework is established, categorizing MGAs techniques into three fundamental domains based on their underlying dynamical mechanisms:(1) escape and capture orbit techniques,(2) diverse transfer trajectory designs, and(3) orbit adjustment and directional control strategies. Our analysis in each category connects representative methods to their real-world applications and missions. Finally, future research prospects are outlined, aiming to ultimately support the development of advanced MGA-based trajectory planning for deep space missions.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(No.52325506)the Fundamental Research Funds for the Central Universities(No.DUT22LAB501)。
文摘Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.
文摘BACKGROUND:Hemiplegia,a prevalent stroke-related condition,is often studied for motor dysfunction;however,spasticity remains under-researched.Abnormal muscle tone significantly hinders hemiplegic patients’walking recovery.OBJECTIVE:To determine whether early suspension-protected training with a personal assistant machine for stroke patients enhances walking ability and prevents muscle spasms.METHODS:Thirty-two early-stage stroke patients from Shenzhen University General Hospital and the China Rehabilitation Research Center were randomly assigned to the experimental group(n=16)and the control group(n=16).Both groups underwent 4 weeks of gait training under the suspension protection system for 30 minutes daily,5 days a week.The experimental group used the personal assistant machine during training.Three-dimensional gait analysis(using the Cortex motion capture system),Brunnstrom staging,Fugl-Meyer Assessment for lower limb motor function,Fugl-Meyer balance function,and the modified Ashworth Scale were evaluated within 1 week before the intervention and after 4 weeks of intervention.RESULTS AND CONCLUSION:After the 4-week intervention,all outcome measures showed significant changes in each group.The experimental group had a small but significant increase in the modified Ashworth Scale score(P<0.05,d=|0.15|),while the control group had a large significant increase(P<0.05,d=|1.48|).The experimental group demonstrated greater improvements in walking speed(16.5 to 38.44 cm/s,P<0.05,d=|4.01|),step frequency(46.44 to 64.94 steps/min,P<0.05,d=|2.32|),stride length(15.50 to 29.81 cm,P<0.05,d=|3.44|),and peak hip and knee flexion(d=|1.82|to|2.17|).After treatment,the experimental group showed significantly greater improvements than the control group in walking speed(38.44 vs.26.63 cm/s,P<0.05,d=|2.75|),stride length,peak hip and knee flexion(d=|1.31|to|1.45|),step frequency(64.94 vs.59.38 steps/min,P<0.05,d=|0.85|),and a reduced support phase(bilateral:24.31%vs.28.38%,P<0.05,d=|0.88|;non-paretic:66.19%vs.70.13%,P<0.05,d=|0.94|).For early hemiplegia,personal assistant machine-assisted gait training under the suspension protection system helps establish a correct gait pattern,prevents muscle spasms,and improves motor function.
文摘Hebei Province has incorporated targeted assistance services for people with disabilities into livelihood projects,upgrading the quality and efficiency of support services for disadvantaged groups.THE living and nursing allowances provided by the Chinese government for people with disabilities who are unable to work are not only important components of China’s social security system which provide for the needs of its disabled,but also show China’s ability to guarantee the basic living standard and social fairness and justice for this group of people.
文摘Objective:To identify predictors of pregnancy and live birth outcomes in assisted reproductive technology(ART)cycles based on patient characteristics,hormonal profile,and embryo transfer variables.Methods:This retrospective cohort study included 50 fresh in vitro fertilization(IVF)/intracytoplasmic sperm injection(ICSI)cycles selected from ART participants at a single tertiary ART center.Controlled ovarian stimulation was performed using recombinant follicle stimulating hormone(rFSH),gonadotropin-releasing hormone(GnRH)antagonist,and menotropins;oocyte retrieval occurred 36 h after trigger and embryo transfer was performed on day 3 or 5.Outcomes(chemical pregnancy,ongoing pregnancy,abortion,live birth)were compared across groups stratified by maternal age,antral follicle count(AFC),anti-Müllerian hormone(AMH),baseline luteinizing hormone(LH),estradiol(E2)at trigger,and endometrial thickness.Multivariate regression was used to identify independent predictors of live birth.Results:A total of 124 ART patients were screened during the study period,of whom 50 participants meeting the eligibility criteria were included in the final analysis.The median age of the participants was 35.8 years[interquartile range(IQR)32.5–39.6].The median AFC was 8(IQR 4–14),AMH level was 1.4 ng/mL(IQR 0.7–2.9),and the median endometrial thickness at embryo transfer was 10.2 mm(IQR 9.0–11.3).Chemical,ongoing,abortion,and live birth rates were 62%,32%,12%,and 16%,respectively.Younger maternal age(<35 years),higher AFC(>12),AMH 1–4 ng/mL,and endometrial thickness≥10 mm were associated with more favorable pregnancy outcomes.In multivariate analysis,higher baseline LH(β=0.089;95%CI 0.017–0.162;P=0.02)and greater endometrial thickness(β=0.145;95%CI 0.011–0.278;P=0.04)independently predicted live birth,whereas age,AFC,AMH,and E2 did not.Conclusions:Maternal age,ovarian reserve markers,LH levels,and endometrial thickness collectively influence ART outcomes.Baseline LH and endometrial receptivity are key independent predictors of live birth and may guide individualized treatment strategies.
基金the China National Petroleum Corporation’s Forward-Looking Fundamental Technology Breakthrough Project(2021DJ2305).
文摘Self-suspended proppants,which enable clear-water fracturing,represent a promising new class of materials for reservoir stimulation.Given the economic limitations associated with their exclusive use,this study investigates proppant transport behavior in hybrid systems combining self-suspended proppants with conventional 40/70 mesh quartz sand at various mixing ratios.A dedicated experimental apparatus was developed to replicate field-relevant complex fracture networks,consisting of a main fracture and two branching fractures with different deflection angles.Using this system,sand bank formation and proppant distribution were examined for both conventional quartz sand fracturing and fracturing augmented with self-suspended proppants.The effects of slurry discharge volume,proppant mixing ratio,sand ratio,and injection location of the self-suspended proppant on transport and placement behavior were systematically analyzed.According to the results,the incorporation of self-suspended proppants markedly enhances the proppant-carrying capacity of the slurry and substantially modifies sand bank morphology.Increasing the discharge volume raises the inlet slope angle and promotes greater proppant penetration into branch fractures.The proportion of self-suspended proppant governs slurry viscoelasticity and,consequently,proppant settling behavior.As the fraction of self-suspended proppant decreases,the equilibrium height of the sand bank increases,while the proppant mass fraction within branch fractures exhibits a non-monotonic response,initially decreasing and then increasing.Variations in sand ratio alter both overall proppant concentration and the self-suspended proppant-to-water ratio,thereby modulating slurry rheology and influencing proppant placement.In addition,changes in injection location affect near-wellbore vortex structures,leading to distinct sand bank morphologies.
基金financially supported by the National Natural Science Foundation of China(Nos.52034005,52227807,52104383,and 52222410)the Shaanxi Province National Science Fund for Distinguished Young Scholars,China(No.2022JC-24)+1 种基金the Key Research and Development Program of Shaanxi Province,China(No.2022JBGS2-01)the Central Guidance on Local Science and TechnologyDevelopment Fund of Shaanxi Province,China(No.2024ZY-JCYJ-04-09).
文摘Twinning-induced plasticity(TWIP)steel was processed using electrically assisted friction stir welding(EFSW).The microstructure,mechanical properties,and deformation behavior of the welded joints were systematically investigated.The results show that the average grain size was refined from 3.67μm in the base material(BM)to 1.39μm in the stir zone(SZ),while it increased to 4.19μm in the heat-affected zone(HAZ).The fraction of twin boundaries(TBs)decreased from 20.7%in the BM to 6.9%in the SZ and increased to24.5%in the HAZ.The ultimate tensile strength,yield strength,and elongation of the BM were 1021 MPa,505 MPa,and 65.8%,respectively.In comparison,the EFSW joint exhibited values of 1055 MPa,561 MPa,and 60.8%,corresponding to 103.3%,111.1%,and 92.4%of those of the BM,respectively.During tensile testing,plastic deformation was primarily concentrated in the BM,although both the SZ and HAZ also exhibited notable plastic deformation.Fracture ultimately occurred in the BM.
基金supported by National Natural Science Foundation of China(No.52025055 and 52275571)Basic Research Operation Fund of China(No.xzy012024024).
文摘Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.
文摘Dear Editor,We present this case report which discusses a patient who underwent flap amputation after repeated attempts to resolve persistent and severe epithelial ingrowth following laser-assisted in situ keratomileusis(LASIK)surgery.Epithelial ingrowth is a known complication of LASIK surgery,typically manageable with minimal measures.However,severe cases may necessitate more aggressive interventions,such as flap amputation[1].LASIK is a widely performed refractive surgery with high success rates and excellent visual outcome[2].
文摘Objective:To investigate the impact of anti-Müllerian hormone(AMH)levels on the outcomes of intracytoplasmic sperm injection(ICSI)cycles in women of advanced age and also to explore the effect of age on the ICSI results in patients with low AMH levels.Methods:This retrospective cohort study involved 143 infertile couples undergoing ICSI cycles at a fertility clinic in Iran from November 2021 to November 2023.Women aged<37 years with AMH<1 ng/mL and those aged≥37 years were included.A standardized ovarian stimulation protocol was followed,leading to oocyte retrieval and ICSI on mature oocytes.Key oocyte quality indexes,including the maturation rate,fertilization rate,and embryo quality metrics,were evaluated.Poisson regression analyses were also employed to investigate the association between AMH levels and oocyte quality parameters in the advanced age groups,as well as the association between age and oocyte quality parameters in patients with low AMH.Results:We analyzed 143 ICSI cycles from 143 infertile couples.The mean ages of the women and their partners were(38.2±4.7)years and(40.6±5.9)years,respectively,with a median(IQR)AMH level of 0.7(0.4–2.0)ng/mL.Younger women with low AMH levels(<1 ng/mL)showed significantly better outcomes in terms of the number of MⅡ oocytes[adjusted odds ratio(aOR)1.89,95%CI 1.31-2.71;P=0.001],fertilized(2PN)oocytes(aOR 1.97,95%CI 1.36-2.86;P<0.001),embryo number(aOR 2.16,95%CI 1.44-3.24;P<0.001),and embryos suitable for freezing(aOR 2.88,95%CI 1.80-4.61;P<0.001)compared to advanced-age women.Furthermore,among women of advanced age,those with normal AMH levels exhibited a significantly higher number of MⅡ oocyte(aOR 3.55,95%CI 2.31-5.44;P<0.001),fertilized(2PN)oocytes(aOR 3.54,95%CI 2.29-5.49;P<0.001),embryo number(aOR 3.89,95%CI 2.48-6.10;P<0.001),and embryos suitable for freezing(aOR 4.75,95%CI 2.79-8.09;P<0.001)compared to those with low AMH levels.Conclusions:AMH level is a significant predictor of oocyte and embryo number and quality in infertile women of advanced age undergoing ICSI cycles.Our findings suggest that maternal age markedly impacts the quality of oocytes and embryos in low AMHlevel patients.
基金supported by the National Natural Science Foundation of China(No.52205468,No.52275431,No.52375186)China Postdoctoral Science Foundation(No.2025M771349)Zhejiang Province Natural Science Foundation(No.LD22E050001)。
文摘The latest generation of aero engines has set higher standards for thrust-to-weight ratio and energy conversion efficiency,making it imperative to address the challenge of efficiently and accurately machining film cooling holes.It has been demonstrated that conventional long-pulse lasers are incapable of meeting the elevated quality surface finish requirements for these holes,a consequence of the severe thermal defects.The employment of backside water-assisted laser drilling technology confers a number of distinct advantages in terms of mitigating laser thermal damage,thus representing a highly promising solution to this challenge.However,significant accumulation of bubbles and machining products during the backside water-assisted laser drilling process has been demonstrated to have a detrimental effect on laser transmission and machining stability,thereby reducing machining quality.In order to surmount these challenges,a novel method has been proposed,namely an ultrasonic shock water flow-assisted picosecond laser drilling technique.Numerical models for ultrasonic acoustic streaming and particle tracking for machining product transport have been established to investigate the mechanism.The simulation results demonstrated that the majority of the machining products could rapidly move away from the machining area because of the action of acoustic streaming,thereby avoiding the accumulation of bubbles and products.Subsequent analysis,comparing the process performance in micro-hole machining,confirmed that the ultrasonic field could effectively eliminate bubble and chip accumulation,thus significantly improving micro-hole quality.Furthermore,the impact of ultrasonic and laser parameters on micro-hole quality under varying machining methods was thoroughly investigated.The findings demonstrated that the novel methodology outlined in this study yielded superior-quality micro-holes at elevated ultrasonic and laser power levels,in conjunction with reduced laser frequency and scanning velocity.The taper of the micro-holes produced by the new method was reduced by more than 25%compared with the other conventional methods.
文摘Based on the Bismuth-Corlette classification of hilar cholangiocarcinoma,the patients with types I,II,and III can undergo radical resection in the absence of extensive intrahepatic metastasis and vascular invasion[1].Depending on the scope of tumor invasion in bile duct,a combined resection of parts of the liver,hepatic ducts,common bile ducts,regional lymph nodes,and even parts of the duodenum and pancreas is necessary,along with biliary and gastrointestinal reconstructions[2].The surgical plan is complex,involving a large resection area and significant trauma.In recent years,laparoscopic or robot assisted radical resection of hilar cholangiocarcinoma has been applied clinically[3,4].With the advanced laparoscopic equipment,many patients undergo hepatopancreatoduodenectomy successfully[5].The limitations of traditional laparoscopic techniques restrict their wide application in clinical practice.However,the Da Vinci robot has been widely applied due to its clear field of vision and flexible manipulation.However,its utilization in hepato-pancreatoduodenectomy for hilar cholangiocarcinoma is still relatively rare.Here,we report a case with hilar cholangiocarcinoma at clinical stage IIIb who underwent robot-assisted hepato-pancreatoduodenectomy.
文摘Rationale:This case report describes a couple with recurrent fertilization failure despite undergoing multiple cycles of intracytoplasmic sperm injection(ICSI).The principal clinical concern was suspected oocyte activation deficiency(OAD),in which fertilization is impeded due to the oocyte’s inability to initiate embryogenesis,commonly attributed to inadequate intracellular calcium(Ca^(2+))release following sperm injection.Patient concerns:The couple repeatedly experienced complete or near-complete fertilization failure in previous ICSI cycles,raising suspicion of an underlying oocyte activation defect.Diagnosis:Based on the repeated absence of fertilization post-ICSI and clinical history,a diagnosis of suspected OAD leading to recurrent ICSI fertilization failure was considered.Interventions:Artificial oocyte activation(AOA)using the calcium ionophore A23187 was performed.After ICSI,unfertilized oocytes were exposed to the ionophore to induce Ca^(2+)influx,simulating physiological calcium oscillations essential for oocyte activation.The efficacy of intervention was evaluated through subsequent embryonic development,morphological grading,and chromosomal integrity.Outcomes:Following AOA treatment,successful oocyte activation occurred,resulting in the formation of high-grade embryos with normal developmental progression.Chromosomal analysis revealed no detectable abnormalities,indicating genomic stability.Lessons:Calcium ionophore–mediated AOA may serve as an effective adjunct in cases of recurrent ICSI failure attributed to OAD.This case highlights the importance of individualized therapeutic strategies in assisted reproduction;however,further research is needed to refine protocols,validate broader clinical efficacy,and assess long-term safety,including potential epigenetic risks.
基金supported in part by the National Natural Science Foundation of China(62173048,62373065,61873304,62106023)the Key Science and Technology Projects of Jilin Province,China(20230204081YY)the Research and Innovation Team of Anhui Province(2024AH010023)。
文摘Dear Editor,This letter presents a model predictive control(MPC)scheme for human-robot interaction(HRI)in a multi-joint exoskeleton robot(ER)driven by series elastic actuator(SEA).The proposed scheme in robot-in-charge(RIC)mode facilitates the ER driven by SEA to provide the required assistance and support for the subject.
基金supported by the National Natural Science Foundation of China (NSFC 52175352)。
文摘Electroslag remelting(ESR) is an important metallurgical process for producing high-purity materials with homogeneous compositions and sound microstructures,and its typical products are ingots or simple castings.The core principle involves the resistive melting of a consumable electrode within a slag pool,followed by the refining of molten metal droplets as they traverse the slag,and subsequent sequential solidification in a water-cooled mold.However,conventional ESR processes face limitations in producing large or complex-shaped components,enhancing production efficiency,achieving highly specialized microstructures,and meeting ultra-high purity demands for advanced applications.Advanced composite ESR technologies have been developed to overcome these limitations by innovatively modifying key process aspects.For instance,electrode systems are improved using vibration,rotation,or multiple electrodes.Enhanced mold design and solidification control are achieved through techniques including conductive molds,mold rotation,and ingot withdrawal.Precise control of the process is realized through the use of protective gas,vacuum,or elevated pressure,as well as the application of external fields such as magnetic fields or ultrasonic vibration.This review comprehensively summarizes these advanced techniques,examining their principles and characteristics,and discussing their specific advantages and challenges.
基金supported by the National Natural Science Foundation of China (Grant Nos.12474477,12550405,and 61888102)the Beijing Outstanding Young Scientist Program+4 种基金the National Key R&D Program of China (Grant No.2024YFA1207700)the Fundamental Research Funds for the Central Universitiesthe Scientific Research Innovation Capability Support Project for Young Faculty (Grant No.SRICSPYF- ZY2025071)the Robotic AI-Scientist Platform of the Chinese Academy of Sciencesfinancial support from the Flemish Research Foundation (Grant Nos.FWO/11E5821N and FWO/G0A5921N)。
文摘erized by a periodic real-space modulation of the superconducting pairing order parameter,is a novel quantum phase observed in superconducting(SC)systems.It is believed to play a key role in understanding the pseudogap phase of superconductors and has recently been discovered in bulk cuprates,transition-metal dichalcogenide,and other unconventional superconductors.However,artificially engineered PDW in designable two-dimensional materials remain rare.In this paper,we report a strain-assisted strategy to realize cooper-pair density modulation in a van der Waals heterostructure:graphene on SC 2H-NbSe2.Superconductivity is induced in graphene via the proximity effect.Meanwhile,the graphene membrane spontaneously buckles into a periodic structure owing to strain,featuring a spatially modulated local density of states(LDOS).The interplay between the spatially modulated LDOS and the proximity-induced superconductivity results in an oscillatory pair density determined by the buckled geometry,constituting an artificial PDW.This approach enables the engineering of PDWs with periodicities of up to tens of nanometers and allows their realization in a variety of heterostructures with tailored designs.Our work provides new insights into the investigation of PDW physics using predesigned two-dimensional materials.
基金the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2024-00344633)HYC acknowledges the financial support from the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2023-00211360)Biomaterials Specialized Graduate Program through the Korea Environmental Industry&Technology Institute(KEITI)funded by the Ministry of Environment(MOE).
文摘Genomic disorders affecting the central nervous system(CNS)are among the most complex and devastating conditions in human health.Moreover,these disorders,such as Rett syndrome,spinal muscular atrophy,and Fragile X syndrome,are typically caused by mutations in genes essential for neural development,synaptic function,or cellular homeostasis.Despite the genetic diversity involved,these diseases share key pathological features,including progressive neurodegeneration,disruption of neural circuits,and loss of cognitive or motor function.Meanwhile,one of the significant clinical challenges in treating CNS disorders is the limited regenerative capacity of the adult nervous system,which makes reversing disease progression extremely difficult once symptoms appear.In addition,the blood-brain barrier(BBB)restricts the passage of most systemically administered therapeutics,further complicating effective intervention.Consequently,current treatment options remain largely palliative,and effective cures remain elusive.
基金partially supported by the National Natural Science Foundation of China(Nos.32471474 and 82102574)the Precision Medicine Project of People’s Hospital of Xinjiang Uygur Autonomous Region(No.20220305)+4 种基金Chengdu Advanced Metal Materials Industry Technology Research Institute Co.,Ltd.Support Project(No.24H0802)Sichuan Science and Technology Program(Nos.2025YFHZ0086,2023YFS0053,2024YFHZ0125,and 2025ZNSFSC0381)Project of Tianfu Jincheng Laboratory(No.2025ZH009)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515220102)Xinjiang Autonomous Region Science and Technology Support Project Plan(Directive)Project(No.2024E02049)。
文摘Cases of widespread bone hydatid infection are relatively rare in clinical practice.In this study,we reported for the first time a validated integrated repair therapy for multiple bone tissues,including the hip,femur,and knee,caused by echinococ cosis.Artificial intelligence(AI)was used to develop a targeted surgical plan and to design a personalized prosthesis.Finite element analysis(FEA)was used to optimize the mechanical effectiveness of a customized integrated replacement prosthesis and to model stress distribution in the surrounding bone.Three-dimensional(3 D)printing was used to fabricate a customized prosthesis.With the assistance of AI,FEA,and 3 D printing technology,a personalized surgical plan and customized prosthesis were successfully constructed based on the patient’s disease.This approach achieved a successful therapeutic effect,demonstrating that AI-assisted personalized medicine holds great promise for the future.
基金supported by the National Natural Science Foundation of China(Grant No.11432001)the Tsinghua University Initiative Scientific Research Program(Grant No.20131089268)
文摘Near-Earth asteroids have gained a lot of interest and the development in low-thrust propulsion technology makes complex deep space exploration missions possible. A mission from low-Earth orbit using low-thrust electric propulsion system to rendezvous with near-Earth asteroid and bring sample back is investigated. By dividing the mission into five segments, the complex mission is solved separately. Then different methods are used to find optimal trajectories for every segment. Multiple revolutions around the Earth and multiple Moon gravity assists are used to decrease the fuel consumption to escape from the Earth. To avoid possible numerical difficulty of indirect methods, a direct method to parameterize the switching moment and direction of thrust vector is proposed. To maximize the mass of sample, optimal control theory and homotopic approach are applied to find the optimal trajectory. Direct methods of finding proper time to brake the spacecraft using Moon gravity assist are also proposed. Practical techniques including both direct and indirect methods are investigated to optimize trajectories for different segments and they can be easily extended to other missions and more precise dynamic model.
