Porous hydrogel sensors have attracted significant attention in fields such as smart wearables and medical monitoring due to their high sensitivity.However,existing fabrication methods typically degrade the surface sm...Porous hydrogel sensors have attracted significant attention in fields such as smart wearables and medical monitoring due to their high sensitivity.However,existing fabrication methods typically degrade the surface smoothness of hydrogels when introducing porous structures and face significant challenges in removing fillers completely.To address these challenges,we herein introduce a novel one-step,thermosensitive spray-coating technique for the preparation of aircell hydrogel(ACH).This method leverages the rapid cooling of a thermoresponsive gelatin methacryloyl solution through atomization,enabling rapid cross-linking within seconds and air bubbles encapsulated in situ.Additionally,the transient flow of the pre-gel facilitates the repair of voids formed by ruptured surface bubbles,leading to the creation of the ACH with uniformly distributed inner air bubbles and a smooth outer surface.The mold-free fabrication method is independent of substrate surface properties,enabling the creation of a porous hydrogel film with a thickness as thin as 163 µm.Furthermore,the dual-crosslinked network endows the ACH with excellent anti-swelling properties,and the physical crosslinking between gelatin molecules allows the ACH to self-heal.The ACH exhibits excellent sensitivity in deformation sensing and can even successfully track minor external forces,which enables it to effectively complete various tasks such as facial expression recognition,pitch differentiation,and motion detection.By integrating the ACH into a sensing glove,we also demonstrate the significant potential of the ACH for applications in human-machine interaction and tactile sensing.Ultimately,the ACH sensors are also applied to motion mapping and machine tactile feedback,indicating their promising potential in human-machine interaction.展开更多
We used the ocean reanalysis dataset SODA 2.2.4 to investigate the relationship between the interior branch of subtropical-tropical cells(STCs)in the Pacific Ocean and El Nino-Southern Oscillation(ENSO)over interdecad...We used the ocean reanalysis dataset SODA 2.2.4 to investigate the relationship between the interior branch of subtropical-tropical cells(STCs)in the Pacific Ocean and El Nino-Southern Oscillation(ENSO)over interdecadal timescales between 1930 and 2010,as well as the possible mechanisms involved.Interior transport within the upper pycnocline layers of STCs(InSTC)along 9°S(InSTC9s)shows a significant correlation of 0.54 with ENSO over the study period.However,there is an interdecadal shift in the relationship between InSTC along 9°N(InSTC9n)and ENSO.The correlation coefficient between InSTC9n and ENSO is not statistically significant between 1930 and 1965(PD1),but is as high as 0.68(significant at the 95% confidence level)between 1965 and 2010(PD2).Composite and regression analysis suggests that this shift may be caused by the relationship between InSTC 9 n and the tropical wind field.During PD1,InSTC9n was driven primarily by the local wind field outside equatorial region,with a relatively weak response to the equatorial wind related to ENSO.In contrast,during PD2,the wind field associated with InSTC 9 n showed a similar spatial distribution to that of ENSO within the equatorial region,indicating a close relationship between InSTC9n and ENSO.The wind stress curl associated with ENSO drives the anomalous InSTC9n in off-equatorial regions,whose signal can propagate westward in the form of Rossby wave and modulate the thermal structure of the tropical Pacific,favoring the development of ENSO.The possible connection between the Atlantic Multidecadal Oscillation(AMO)and interdecadal changes in the ENSO-InSTC9n relationship was also examined.There is a significant connection between the AMO and the interdecadal change in the relationship between ENSO and InSTC9n;however,the associated mechanism remains to be explored in future studies.展开更多
An improved large eddy simulation using a dynamic second-order sub-grid-scale （SGS） stress model has been developed to model the governing equations of dense turbulent particle-liquid two-phase flows in a rotating c...An improved large eddy simulation using a dynamic second-order sub-grid-scale （SGS） stress model has been developed to model the governing equations of dense turbulent particle-liquid two-phase flows in a rotating coordinate system, and continuity is conserved by a mass-weighted method to solve the filtered governing equations. In the cur- rent second-order SGS model, the SGS stress is a function of both the resolved strain-rate and rotation-rate tensors, and the model parameters are obtained from the dimensional consistency and the invariants of the strain-rate and the rotation-rate tensors. In the numerical calculation, the finite volume method is used to discretize the governing equations with a staggered grid system. The SIMPLEC algorithm is applied for the solution of the discretized governing equations. Body- fitted coordinates are used to simulate the two-phase flows in complex geometries. Finally the second-order dynamic SGS model is successfully applied to simulate the dense turbu-lent particle-liquid two-phase flows in a centrifugal impeller. The predicted pressure and velocity distributions are in good agreement with experimental results.展开更多
A new instantaneous mobile bed thickness model is presented for sediment transport in skewed asymmetric oscillatory sheet flows. The proposed model includes a basic bed load part and a suspended load part related to t...A new instantaneous mobile bed thickness model is presented for sediment transport in skewed asymmetric oscillatory sheet flows. The proposed model includes a basic bed load part and a suspended load part related to the Shields parameter, and takes into account the effects of mass conservation, phase-lag, and asymmetric boundary layer development, which are important in skewed asymmetric flows but usually absent in classical models. The proposed model is validated by erosion depth and sheet flow layer thickness data in both steady and unsteady flows, and applied to a new instantaneous sediment transport rate formula. With higher accuracy than classical empirical models in steady flows, the new formula can also be used for instantaneous sediment transport rate prediction in skewed asymmetric oscillatory sheet flows.展开更多
Objective:To evaluate the features of testicular torsion presenting with acute abdominal pain and to raise awareness of testicular torsion with specific symptoms.Methods:From October 2005 to June 2016,nine patients wi...Objective:To evaluate the features of testicular torsion presenting with acute abdominal pain and to raise awareness of testicular torsion with specific symptoms.Methods:From October 2005 to June 2016,nine patients with testicular torsion who presented with isolated acute abdominal pain rather than scrotal pain as their primary symptom were retrospectively reviewed.Data,including the age of patients,season at admission,initial medical history,external genital examination,emergency ultrasound findings,operative findings,duration of abdominal pain,complications,and follow-up results,were collected.Results:The average age of patients was 14 years(range 10-17 years).Seven patients whose genitals were not initially examined externally were misdiagnosed as having ordinary abdominal diseases.Surgical exploration revealed that all the involved testes necrotized,and orchidectomy was performed.In the other two patients,scrotal and testicular abnormalities were detected immediately on admission,and emergency surgical exploration determined that the involved testis remained vital,so orchiopexy was performed.The mean duration from symptom onset to diagnosis was 4 h(3-5 h)in the orchiopexy group and 37 h(18-72 h)in the orchidectomy group.Six patients were psychologically affected during postoperative follow-up.Neither recurrence of testicular torsion nor testicular atrophy was recorded.Conclusion:Acute abdominal pain can be the initial and sole symptom of testicular torsion in young males.Physicians should pay close attention to the specific clinical presentation of testicular torsion.展开更多
A liquid film flow over a flat plate is investigated by prescribing the unsteady interface velocity. With this prescribed surface velocity, the governing Navier–Stokes(NS) equations are transformed into a similarity ...A liquid film flow over a flat plate is investigated by prescribing the unsteady interface velocity. With this prescribed surface velocity, the governing Navier–Stokes(NS) equations are transformed into a similarity ordinary differential equation, which is solved numerically. The flow characteristics is controlled by an unsteadiness parameter S and the flow direction parameter Λ. The results show that solutions only exist for a certain range of the unsteadiness parameter, i.e., S≤1 for Λ =-1 and S≤-2.815877 for Λ = 1. In the solution domain,the dimensionless liquid film thickness β decreases with S for both the cases. The wall shear stress increases with the decrease of S for Λ =-1. However, for Λ =-1 the shear stress magnitude first decreases and then increases with the decrease of S. There are no zero crossing points for the velocity profiles for both the cases. The profiles of velocity stay either positive or negative all the time, except for the wall zero velocity. Consequently,the vertical velocity becomes a monotonic function. To maintain the prescribed velocity, mass transpiration is generally needed, but for the shrinking film case it is possible to have an impermeable wall. The results are also an exact solution to the full NS equations.展开更多
Objective:In second-stage percutaneous nephrolithotomy(PCNL),because the hydronephrosis has been decompressed,the dilated renal pelvis has resolved and the space is small.Consequently,introduction of the tip of the Am...Objective:In second-stage percutaneous nephrolithotomy(PCNL),because the hydronephrosis has been decompressed,the dilated renal pelvis has resolved and the space is small.Consequently,introduction of the tip of the Amplatz dilator can cause injury to the opposite side of the renal-pelvic mucosa.In this study,we report the experimental and initial clinical performance of a spherical-headed fascial dilator developed specifically for second-stage PCNL.Methods:The novel spherical-headed dilator was compared with existing tapered-headed dilators in configuration and in puncture resistance utilizing a static puncture test.Subsequently,a pilot clinical study was conducted during which patients scheduled to undergo second-stage PCNL from June 2019 to October 2019 in our center were enrolled.A typical ultrasound guided PCNL procedure was performed with the exception that the new spherical-headed fascial dilator was substituted for a tapered-headed one.Results:Experimentally,stab resistance against polyethylene film was significantly increased using the novel spherical-headed dilator compared to the traditional tapered-headed dilators(p<0.005).In the clinical study,the novel dilators were successfully introduced into the renal pelvis and passed down the collecting system in all eight second-stage PCNL cases.There were no cases of renal pelvic perforation or brisk hemorrhage nor need for transfusion.展开更多
The magnetohydrodynamic（MHD） flow induced by a stretching or shrinking sheet under slip conditions is studied.Analytical solutions based on the boundary layer assumption are obtained in a closed form and can be appl...The magnetohydrodynamic（MHD） flow induced by a stretching or shrinking sheet under slip conditions is studied.Analytical solutions based on the boundary layer assumption are obtained in a closed form and can be applied to a flow configuration with any arbitrary velocity distributions. Seven typical sheet velocity profiles are employed as illustrating examples. The solutions to the slip MHD flow are derived from the general solution and discussed in detail. Different from self-similar boundary layer flows, the flows studied in this work have solutions in explicit analytical forms. However, the current flows require special mass transfer at the wall, which is determined by the moving velocity of the sheet. The effects of the slip parameter, the mass transfer at the wall, and the magnetic field on the flow are also demonstrated.展开更多
Deep gas wells and gas fields have the characteristics of high pressure. The vibration of the tubing string during the production of gas wells causes the string to be subjected to severe stress and even dynamic fatigu...Deep gas wells and gas fields have the characteristics of high pressure. The vibration of the tubing string during the production of gas wells causes the string to be subjected to severe stress and even dynamic fatigue failure. Therefore, this article is based on the dynamic finite element theory, aiming at the characteristics of large-size tubing strings in deep gas wells. The finite element mechanics model and mathematical model of the tubing string vibration of the packer of high-pressure gas wells were established, and the ANSYS software was re-developed. The finite element analysis program for the vibration dynamics of the unbuckled and buckled strings of gas wells was compiled with APDL, and the displacement of the longitudinal vibration of the tubing string of high-pressure gas wells was studied. According to different sizes of tubing strings currently used in deep gas wells and gas fields, simulation calculations are carried out, and the axial impact load and buckling damage laws of the tubing strings of the entire well section under different production rates are obtained. It provides a theoretical basis for the prediction of tubing string vibration law and measures to prevent tubing string vibration.展开更多
Piezoelectric stimulation has garnered substantial interest as a promising strategy for tissue regeneration.However,studies investigating its impact on tendon-to-bone healing characterized by fibrocartilage remain sca...Piezoelectric stimulation has garnered substantial interest as a promising strategy for tissue regeneration.However,studies investigating its impact on tendon-to-bone healing characterized by fibrocartilage remain scarce.Moreover,there are considerable technical challenges in achieving minimally invasive application of piezoelectric stimulation on the irregular tendon-to-bone interface.Herein,we developed Janus asymmetric piezoelectric adhesives by assembling adhesive hydrogel(GAN)and non-adhesive hydrogel(GM)on each side of piezoelectric poly(L-lactic acid)nanofiber.Piezoelectric adhesives exhibited superior anti-inflammatory effects both in vitro and ex vivo.Notably,the transient receptor potential(TRP)ion channels,a class of versatile signaling molecules,are closely associated with the regulation of inflammation.This study demonstrated that piezoelectric stimulation promoted Ca2+influx through the activation of transient receptor potential vanilloid 1(TRPV1),further enhancing cAMP signaling pathway in macrophages by RNA sequencing.Additionally,in vivo proteomic analysis revealed Arachidonic acid metabolism and TNF-αsignaling pathway downregulation and VEGF signaling pathway upregulation in a rat rotator cuff repair model.Piezoelectric adhesives ultimately achieved inflammation alleviation,angiogenesis enhancement,and fibrocartilage regeneration promotion,improving the biomechanical strength of the enthesis.This study elucidated the mechanism by which piezoelectric stimulation regulated tendon-to-bone healing through multi-omics analysis.The piezoelectric adhesives hold promise as a convenient and effective strategy for enhancing tendon-to-bone healing in clinical practice.展开更多
Implantable electronic medical devices(IEMDs)are revolutionary advancements in healthcare,enabling continuous health monitoring and disease treatments.To support their further development,IESDs that include supercapac...Implantable electronic medical devices(IEMDs)are revolutionary advancements in healthcare,enabling continuous health monitoring and disease treatments.To support their further development,IESDs that include supercapacitors(SCs)and batteries are now garnering intensive worldwide research efforts.In this review,we discuss and analyze the research advancements and challenges associated with batteries and SCs in the realm of IESDs.First,we summarize the main components of IESDs,including electrodes,electrolytes,and encapsulation materials.Subsequently,we elucidate the main application scenarios of multifunctional energy storage devices,specifically biosafe,stretchable/self-healing,biodegradable,miniaturized,injectable,and edible IESDs.We then summarize research progress to date on the integration of IESDs with energy harvesters and wireless charging.State-of-the-art studies of IESDs categorized by human organ systems are covered in depth,including cardiovascular,nervous,gastrointestinal,musculoskeletal,vision,and systemic recording and stimulation.We close by briefly outlining the challenges and future prospects for IESDs.展开更多
Bioelectricity has been stated as a key factor in regulating cell activity and tissue function in electroactive tissues.Thus,various biomedical electronic constructs have been developed to interfere with cell behavior...Bioelectricity has been stated as a key factor in regulating cell activity and tissue function in electroactive tissues.Thus,various biomedical electronic constructs have been developed to interfere with cell behaviors to promote tissue regeneration,or to interface with cells or tissue/organ surfaces to acquire physiological status via electrical signals.Benefiting from the outstanding advantages of flexibility,structural diversity,customizable mechanical properties,and tunable distribution of conductive components,conductive fibers are able to avoid the damage-inducing mechanical mismatch between the construct and the biological environment,in return to ensure stable functioning of such constructs during physiological deformation.Herein,this review starts by presenting current fabrication technologies of conductive fibers including wet spinning,microfluidic spinning,electrospinning and 3D printing as well as surface modification on fibers and fiber assemblies.To provide an update on the biomedical applications of conductive fibers and fiber assemblies,we further elaborate conductive fibrous constructs utilized in tissue engineering and regeneration,implantable healthcare bioelectronics,and wearable healthcare bioelectronics.To conclude,current challenges and future perspectives of biomedical electronic constructs built by conductive fibers are discussed.展开更多
Ligament regeneration is a complicated process that requires dynamic mechanical properties and allowable space to regulate collagen remodeling.Poor strength and limited space of currently available grafts hinder tissu...Ligament regeneration is a complicated process that requires dynamic mechanical properties and allowable space to regulate collagen remodeling.Poor strength and limited space of currently available grafts hinder tissue regeneration,yielding a disappointing success rate in ligament reconstruction.Matching the scaffold retreat rate with the mechanical and spatial properties of the regeneration process remains challenging.Herein,a scaffold matching the regeneration process was designed via regulating the trajectories of fibers with different degradation rates to provide dynamic mechanical properties and spatial adaptability for collagen infiltration.This core-shell structured scaffold exhibited biomimetic fiber orientation,having tri-phasic mechanical behavior and excellent strength.Besides,by the sequential material degradation,the available space of the scaffold increased from day 6 and remained stable on day 24,consistent with the proliferation and deposition phase of the native ligament regeneration process.Furthermore,mature collagen infiltration and increased bone integration in vivo confirmed the promotion of tissue regeneration by the adaptive space,maintaining an excellent failure load of 67.65%of the native ligament at 16 weeks.This study proved the synergistic effects of dynamic strength and adaptive space.The scaffold matching the regeneration process is expected to open new approaches in ligament reconstruction.展开更多
Recent progress in bioresorbable stents(BRSs)has provided a promising alternative for treating coronary artery disease.However,there is still lack of BRSs with satisfied compression and degradation performance for ped...Recent progress in bioresorbable stents(BRSs)has provided a promising alternative for treating coronary artery disease.However,there is still lack of BRSs with satisfied compression and degradation performance for pediatric patients with congenital heart disease,leading to suboptimal therapy effects.Here,we developed a mechanically self-reinforced composite bioresorbable stent(cBRS)for congenital heart disease application.The cBRS consisted of poly(p-dioxanone)monofilaments and polycaprolactone/poly(p-dioxanone)core-shell composite yarns.Interlacing points in cBRS structure were partially bonded,offering the cBRS with significantly higher compression force compared to typical braids and remained good compliance.The suitable degradation profile of the cBRS can possibly preserve vascular remodeling and healing process.In addition,the controllable structural organization provides a method to customize the performance of the cBRS by altering the proportion of different components in the braids.The in vivo results suggested the cBRS supported the vessel wall similar to that of metallic stent.In both abdominal aorta and iliac artery of porcine,cBRS was entirely endothelialized within 1 month and maintained target vessels with good patency in the 12-month follow-up.The in vivo degradation profile of the cBRS is consistent with static degradation results in vitro.It is also demonstrated that there is minimal impact of pulsatile pressure of blood flow and variation of radial force on the degradation rate of the cBRS.Moreover,the lumen of cBRS implanted vessels were enlarged after 6 months,and significantly larger than the vessels implanted with metallic stent in 12 months.展开更多
Stretchable conductive fibers have attracted much attention due to their potential use in wearable electronics.However,the ultrahigh strain insensitive conductivity is hindered by mechanical mismatch in Young’s modul...Stretchable conductive fibers have attracted much attention due to their potential use in wearable electronics.However,the ultrahigh strain insensitive conductivity is hindered by mechanical mismatch in Young’s modulus and failure of stretchable structures under large deformation.This challenge is addressed with a conductive and elastic multifilament made of the polyurethane monofilaments that are surface-coated with buckled polypyrrole(PPy)of which flexibility is improved by sodium sulfosalicylate.Such parallel conductive monofilaments with PPy buckling on surface reduce the influence of cracks in the conductive coating on the overall conductivity,displaying an ultra-high strain insensitive behavior(quality factor Q=10.9).Remarkably,various complex forms of wearable electronic textiles made by this conductive multifilament maintain the strain-insensitive behavior of the original multifilament,even upon the large deformation of human joint.This multifilament with wrinkled PPy has attractive advantages in the application of super-stretched wearable electronic devices.展开更多
During the postoperative management of urinary diseases,oral or intravenous administration of drugs and implanting ureteral stents are usually required,making localized drug delivery by ureteral stent a precise and ef...During the postoperative management of urinary diseases,oral or intravenous administration of drugs and implanting ureteral stents are usually required,making localized drug delivery by ureteral stent a precise and effective medication strategy.In the traditional drug loading method,the drug was premixed in the implants in production lines and the versatility of drugs was restricted.However,the complex situation in the urinary system fails the possibility of finding a“one fits all”medication plan,and the intraoperative drug-loading of implants is highly desired to support customized therapy.Here,we designed an ultrathin(8μm),elastic,and self-adhesive nanofiber bio-tape(NFBT)that can easily encapsulate drugs on the stent surface for controllable localized drug delivery.The NFBT exhibited high binding strength to a ureteral stent,a sustained release over 7 d in PBS for hydrophilic drug,and a zero-order release curve over 28 days for the hydrophobic drug nitrofurantoin(NFT).Further in vivo experiments using a porcine ureteral tract infection model demonstrated that NFBT loaded with NFT could significantly reduce the bacterial concentration in urine.The total amount of NFT delivered by the NFBT was about 2.68 wt%of the recommended dose for the systemic administration.展开更多
Fibrosis is a common problem in soft tissue regeneration,often caused by the differentiation of fibroblasts into myofibro-blasts.Because of the nanoscale topology that regulates the mechanical transduction of cells,na...Fibrosis is a common problem in soft tissue regeneration,often caused by the differentiation of fibroblasts into myofibro-blasts.Because of the nanoscale topology that regulates the mechanical transduction of cells,nanofibers or nanoparticles are commonly used to modulate fibroblast differentiation.However,the strength of nanofibers is insufficient,and the physi-ological toxicity of nanoparticles still remains to be verified.In this study,self-induced crystallization was used to construct nano-protrusions on the random and aligned polycaprolactone microfibers to regulate the behavior of fibroblasts.The results revealed that the mechanical properties of microfibers with a nanoscale topology were improved.Immunofluorescence staining manifested that nano-protrusions impeded the activation of integrins and vinculins,thereby inhibiting the nuclear transfer of Yes-associated protein,resulting in a decrease in the expression ofα-smooth muscle actin.Nanoscale topology of microfibers hampered the activation of the Rho/ROCK signalling pathway.In general,we used a simple process to con-struct a fibrous scaffold with a micro-nano multilevel structure.This structure can hinder the transformation of fibroblasts into myofibroblasts on both random and aligned fibers,which is expected to prevent fibrosis.展开更多
Lattice Boltzmannmodel(LBM)in conjunction with an accurate Large Eddy Simulation(LES)technology was proposed to simulate various vortical structures and their evolutions in open pump intakes.The strain rate tensor in ...Lattice Boltzmannmodel(LBM)in conjunction with an accurate Large Eddy Simulation(LES)technology was proposed to simulate various vortical structures and their evolutions in open pump intakes.The strain rate tensor in the LES model is locally calculated by means of non-equilibrium moments based on Chapman-Enskog expansion,and bounce-back scheme was used for non-slip condition on solid walls and reflection scheme for free surface.The presentedmodel was applied to investigate free-surface and wall-attached vortices for different water levels and flow rate.The vortex position,shapes and vorticities were predicted successfully under three flowing cases(i.e.critical water level(CWL),lower water level,lower flow rate),and the numerical velocity and streamline distribution were analyzed systematically.For CWL based on Froude number considering open channel flows,the shape and the location of various dynamic vortices were captured.Compare to the experimental results of CWL,more vortices were predicted for lower water level,and less vortices were observed for lower flow rate.The predicted velocities and vortex locations are in good agreement with the experimental of a small physical model.The comparisons demonstrated the feasibility and stability of above-mentioned model and numerical method in predicting vortex flows inside open pump intakes.展开更多
基金financially supported by the National Key R&D Program of China(Grant No.2023YFE0108900)EU HORIZON 2021 L4DNANO(No.101086227)。
文摘Porous hydrogel sensors have attracted significant attention in fields such as smart wearables and medical monitoring due to their high sensitivity.However,existing fabrication methods typically degrade the surface smoothness of hydrogels when introducing porous structures and face significant challenges in removing fillers completely.To address these challenges,we herein introduce a novel one-step,thermosensitive spray-coating technique for the preparation of aircell hydrogel(ACH).This method leverages the rapid cooling of a thermoresponsive gelatin methacryloyl solution through atomization,enabling rapid cross-linking within seconds and air bubbles encapsulated in situ.Additionally,the transient flow of the pre-gel facilitates the repair of voids formed by ruptured surface bubbles,leading to the creation of the ACH with uniformly distributed inner air bubbles and a smooth outer surface.The mold-free fabrication method is independent of substrate surface properties,enabling the creation of a porous hydrogel film with a thickness as thin as 163 µm.Furthermore,the dual-crosslinked network endows the ACH with excellent anti-swelling properties,and the physical crosslinking between gelatin molecules allows the ACH to self-heal.The ACH exhibits excellent sensitivity in deformation sensing and can even successfully track minor external forces,which enables it to effectively complete various tasks such as facial expression recognition,pitch differentiation,and motion detection.By integrating the ACH into a sensing glove,we also demonstrate the significant potential of the ACH for applications in human-machine interaction and tactile sensing.Ultimately,the ACH sensors are also applied to motion mapping and machine tactile feedback,indicating their promising potential in human-machine interaction.
基金Supported by the National Natural Science Foundation of China(No.41976027)the Laoshan Laboratory(No.LSKJ202201601)。
文摘We used the ocean reanalysis dataset SODA 2.2.4 to investigate the relationship between the interior branch of subtropical-tropical cells(STCs)in the Pacific Ocean and El Nino-Southern Oscillation(ENSO)over interdecadal timescales between 1930 and 2010,as well as the possible mechanisms involved.Interior transport within the upper pycnocline layers of STCs(InSTC)along 9°S(InSTC9s)shows a significant correlation of 0.54 with ENSO over the study period.However,there is an interdecadal shift in the relationship between InSTC along 9°N(InSTC9n)and ENSO.The correlation coefficient between InSTC9n and ENSO is not statistically significant between 1930 and 1965(PD1),but is as high as 0.68(significant at the 95% confidence level)between 1965 and 2010(PD2).Composite and regression analysis suggests that this shift may be caused by the relationship between InSTC 9 n and the tropical wind field.During PD1,InSTC9n was driven primarily by the local wind field outside equatorial region,with a relatively weak response to the equatorial wind related to ENSO.In contrast,during PD2,the wind field associated with InSTC 9 n showed a similar spatial distribution to that of ENSO within the equatorial region,indicating a close relationship between InSTC9n and ENSO.The wind stress curl associated with ENSO drives the anomalous InSTC9n in off-equatorial regions,whose signal can propagate westward in the form of Rossby wave and modulate the thermal structure of the tropical Pacific,favoring the development of ENSO.The possible connection between the Atlantic Multidecadal Oscillation(AMO)and interdecadal changes in the ENSO-InSTC9n relationship was also examined.There is a significant connection between the AMO and the interdecadal change in the relationship between ENSO and InSTC9n;however,the associated mechanism remains to be explored in future studies.
基金the National Natural Science Foundation of China(50779069 and 90510007)the Start-up Scientific Research Foundation of China Agricultural University(2006021)the Beijing Natural Science Foundation(3071002).
文摘An improved large eddy simulation using a dynamic second-order sub-grid-scale （SGS） stress model has been developed to model the governing equations of dense turbulent particle-liquid two-phase flows in a rotating coordinate system, and continuity is conserved by a mass-weighted method to solve the filtered governing equations. In the cur- rent second-order SGS model, the SGS stress is a function of both the resolved strain-rate and rotation-rate tensors, and the model parameters are obtained from the dimensional consistency and the invariants of the strain-rate and the rotation-rate tensors. In the numerical calculation, the finite volume method is used to discretize the governing equations with a staggered grid system. The SIMPLEC algorithm is applied for the solution of the discretized governing equations. Body- fitted coordinates are used to simulate the two-phase flows in complex geometries. Finally the second-order dynamic SGS model is successfully applied to simulate the dense turbu-lent particle-liquid two-phase flows in a centrifugal impeller. The predicted pressure and velocity distributions are in good agreement with experimental results.
基金supported by the National Natural Science Foundation of China (Grants 51609244, 11472156, and 51139007)the National Science-Technology Support Plan of China (Grant 2015BAD20B01)
文摘A new instantaneous mobile bed thickness model is presented for sediment transport in skewed asymmetric oscillatory sheet flows. The proposed model includes a basic bed load part and a suspended load part related to the Shields parameter, and takes into account the effects of mass conservation, phase-lag, and asymmetric boundary layer development, which are important in skewed asymmetric flows but usually absent in classical models. The proposed model is validated by erosion depth and sheet flow layer thickness data in both steady and unsteady flows, and applied to a new instantaneous sediment transport rate formula. With higher accuracy than classical empirical models in steady flows, the new formula can also be used for instantaneous sediment transport rate prediction in skewed asymmetric oscillatory sheet flows.
基金The study was partially supported by the Medical Records Room,Heze Municipal Hospital,Shandong Province,China.
文摘Objective:To evaluate the features of testicular torsion presenting with acute abdominal pain and to raise awareness of testicular torsion with specific symptoms.Methods:From October 2005 to June 2016,nine patients with testicular torsion who presented with isolated acute abdominal pain rather than scrotal pain as their primary symptom were retrospectively reviewed.Data,including the age of patients,season at admission,initial medical history,external genital examination,emergency ultrasound findings,operative findings,duration of abdominal pain,complications,and follow-up results,were collected.Results:The average age of patients was 14 years(range 10-17 years).Seven patients whose genitals were not initially examined externally were misdiagnosed as having ordinary abdominal diseases.Surgical exploration revealed that all the involved testes necrotized,and orchidectomy was performed.In the other two patients,scrotal and testicular abnormalities were detected immediately on admission,and emergency surgical exploration determined that the involved testis remained vital,so orchiopexy was performed.The mean duration from symptom onset to diagnosis was 4 h(3-5 h)in the orchiopexy group and 37 h(18-72 h)in the orchidectomy group.Six patients were psychologically affected during postoperative follow-up.Neither recurrence of testicular torsion nor testicular atrophy was recorded.Conclusion:Acute abdominal pain can be the initial and sole symptom of testicular torsion in young males.Physicians should pay close attention to the specific clinical presentation of testicular torsion.
文摘A liquid film flow over a flat plate is investigated by prescribing the unsteady interface velocity. With this prescribed surface velocity, the governing Navier–Stokes(NS) equations are transformed into a similarity ordinary differential equation, which is solved numerically. The flow characteristics is controlled by an unsteadiness parameter S and the flow direction parameter Λ. The results show that solutions only exist for a certain range of the unsteadiness parameter, i.e., S≤1 for Λ =-1 and S≤-2.815877 for Λ = 1. In the solution domain,the dimensionless liquid film thickness β decreases with S for both the cases. The wall shear stress increases with the decrease of S for Λ =-1. However, for Λ =-1 the shear stress magnitude first decreases and then increases with the decrease of S. There are no zero crossing points for the velocity profiles for both the cases. The profiles of velocity stay either positive or negative all the time, except for the wall zero velocity. Consequently,the vertical velocity becomes a monotonic function. To maintain the prescribed velocity, mass transpiration is generally needed, but for the shrinking film case it is possible to have an impermeable wall. The results are also an exact solution to the full NS equations.
基金This study was funded by grants from Shanghai Sailing Program(19YF1427200)National Natural Science Foundation of China(81902556)+2 种基金Shanghai Municipal Commission of Health and Family Planning Program(20184Y0151)Shanghai Association of Chinese Integrative Medicine Program(ZHYY-ZXYJHZX-1-03)Shanghai Ninth People’s Hospital Chuangke Projects(CK2018009).
文摘Objective:In second-stage percutaneous nephrolithotomy(PCNL),because the hydronephrosis has been decompressed,the dilated renal pelvis has resolved and the space is small.Consequently,introduction of the tip of the Amplatz dilator can cause injury to the opposite side of the renal-pelvic mucosa.In this study,we report the experimental and initial clinical performance of a spherical-headed fascial dilator developed specifically for second-stage PCNL.Methods:The novel spherical-headed dilator was compared with existing tapered-headed dilators in configuration and in puncture resistance utilizing a static puncture test.Subsequently,a pilot clinical study was conducted during which patients scheduled to undergo second-stage PCNL from June 2019 to October 2019 in our center were enrolled.A typical ultrasound guided PCNL procedure was performed with the exception that the new spherical-headed fascial dilator was substituted for a tapered-headed one.Results:Experimentally,stab resistance against polyethylene film was significantly increased using the novel spherical-headed dilator compared to the traditional tapered-headed dilators(p<0.005).In the clinical study,the novel dilators were successfully introduced into the renal pelvis and passed down the collecting system in all eight second-stage PCNL cases.There were no cases of renal pelvic perforation or brisk hemorrhage nor need for transfusion.
文摘The magnetohydrodynamic（MHD） flow induced by a stretching or shrinking sheet under slip conditions is studied.Analytical solutions based on the boundary layer assumption are obtained in a closed form and can be applied to a flow configuration with any arbitrary velocity distributions. Seven typical sheet velocity profiles are employed as illustrating examples. The solutions to the slip MHD flow are derived from the general solution and discussed in detail. Different from self-similar boundary layer flows, the flows studied in this work have solutions in explicit analytical forms. However, the current flows require special mass transfer at the wall, which is determined by the moving velocity of the sheet. The effects of the slip parameter, the mass transfer at the wall, and the magnetic field on the flow are also demonstrated.
文摘Deep gas wells and gas fields have the characteristics of high pressure. The vibration of the tubing string during the production of gas wells causes the string to be subjected to severe stress and even dynamic fatigue failure. Therefore, this article is based on the dynamic finite element theory, aiming at the characteristics of large-size tubing strings in deep gas wells. The finite element mechanics model and mathematical model of the tubing string vibration of the packer of high-pressure gas wells were established, and the ANSYS software was re-developed. The finite element analysis program for the vibration dynamics of the unbuckled and buckled strings of gas wells was compiled with APDL, and the displacement of the longitudinal vibration of the tubing string of high-pressure gas wells was studied. According to different sizes of tubing strings currently used in deep gas wells and gas fields, simulation calculations are carried out, and the axial impact load and buckling damage laws of the tubing strings of the entire well section under different production rates are obtained. It provides a theoretical basis for the prediction of tubing string vibration law and measures to prevent tubing string vibration.
基金the National Natural Science Foundation of China(Grant No.82372491,82172509,82102634,32371402).
文摘Piezoelectric stimulation has garnered substantial interest as a promising strategy for tissue regeneration.However,studies investigating its impact on tendon-to-bone healing characterized by fibrocartilage remain scarce.Moreover,there are considerable technical challenges in achieving minimally invasive application of piezoelectric stimulation on the irregular tendon-to-bone interface.Herein,we developed Janus asymmetric piezoelectric adhesives by assembling adhesive hydrogel(GAN)and non-adhesive hydrogel(GM)on each side of piezoelectric poly(L-lactic acid)nanofiber.Piezoelectric adhesives exhibited superior anti-inflammatory effects both in vitro and ex vivo.Notably,the transient receptor potential(TRP)ion channels,a class of versatile signaling molecules,are closely associated with the regulation of inflammation.This study demonstrated that piezoelectric stimulation promoted Ca2+influx through the activation of transient receptor potential vanilloid 1(TRPV1),further enhancing cAMP signaling pathway in macrophages by RNA sequencing.Additionally,in vivo proteomic analysis revealed Arachidonic acid metabolism and TNF-αsignaling pathway downregulation and VEGF signaling pathway upregulation in a rat rotator cuff repair model.Piezoelectric adhesives ultimately achieved inflammation alleviation,angiogenesis enhancement,and fibrocartilage regeneration promotion,improving the biomechanical strength of the enthesis.This study elucidated the mechanism by which piezoelectric stimulation regulated tendon-to-bone healing through multi-omics analysis.The piezoelectric adhesives hold promise as a convenient and effective strategy for enhancing tendon-to-bone healing in clinical practice.
基金support from the Natural Science Foundation of Shanghai(Grant No.23ZR1401500)the Fundamental Research Funds for the Central Universities(CUSF-DH-T-2023051)the Fundamental Research Funds for the DHU Distinguished Young Professor Program.
文摘Implantable electronic medical devices(IEMDs)are revolutionary advancements in healthcare,enabling continuous health monitoring and disease treatments.To support their further development,IESDs that include supercapacitors(SCs)and batteries are now garnering intensive worldwide research efforts.In this review,we discuss and analyze the research advancements and challenges associated with batteries and SCs in the realm of IESDs.First,we summarize the main components of IESDs,including electrodes,electrolytes,and encapsulation materials.Subsequently,we elucidate the main application scenarios of multifunctional energy storage devices,specifically biosafe,stretchable/self-healing,biodegradable,miniaturized,injectable,and edible IESDs.We then summarize research progress to date on the integration of IESDs with energy harvesters and wireless charging.State-of-the-art studies of IESDs categorized by human organ systems are covered in depth,including cardiovascular,nervous,gastrointestinal,musculoskeletal,vision,and systemic recording and stimulation.We close by briefly outlining the challenges and future prospects for IESDs.
基金The authors acknowledge the support from the National Natural Science Foundation of China(Grant No.52005097)the Natural Science Foundation of Shanghai(Grant No.21ZR1401300)+3 种基金the Fundamental Research Funds for the Central Universities(2232022A-05)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(CUSF-DH-D-2021022)the 111 Project(Grant No.BP0719035)the Fundamental Research Funds for DHU Distinguished Young Professor Program.
文摘Bioelectricity has been stated as a key factor in regulating cell activity and tissue function in electroactive tissues.Thus,various biomedical electronic constructs have been developed to interfere with cell behaviors to promote tissue regeneration,or to interface with cells or tissue/organ surfaces to acquire physiological status via electrical signals.Benefiting from the outstanding advantages of flexibility,structural diversity,customizable mechanical properties,and tunable distribution of conductive components,conductive fibers are able to avoid the damage-inducing mechanical mismatch between the construct and the biological environment,in return to ensure stable functioning of such constructs during physiological deformation.Herein,this review starts by presenting current fabrication technologies of conductive fibers including wet spinning,microfluidic spinning,electrospinning and 3D printing as well as surface modification on fibers and fiber assemblies.To provide an update on the biomedical applications of conductive fibers and fiber assemblies,we further elaborate conductive fibrous constructs utilized in tissue engineering and regeneration,implantable healthcare bioelectronics,and wearable healthcare bioelectronics.To conclude,current challenges and future perspectives of biomedical electronic constructs built by conductive fibers are discussed.
基金This work was supported by the National Key Research and Development Program of China(2018YFC1106200,2018YFC1106201)the Fundamental Research Funds for the Central Universities(2232020G-01)the 111 Project(BP0719035).
文摘Ligament regeneration is a complicated process that requires dynamic mechanical properties and allowable space to regulate collagen remodeling.Poor strength and limited space of currently available grafts hinder tissue regeneration,yielding a disappointing success rate in ligament reconstruction.Matching the scaffold retreat rate with the mechanical and spatial properties of the regeneration process remains challenging.Herein,a scaffold matching the regeneration process was designed via regulating the trajectories of fibers with different degradation rates to provide dynamic mechanical properties and spatial adaptability for collagen infiltration.This core-shell structured scaffold exhibited biomimetic fiber orientation,having tri-phasic mechanical behavior and excellent strength.Besides,by the sequential material degradation,the available space of the scaffold increased from day 6 and remained stable on day 24,consistent with the proliferation and deposition phase of the native ligament regeneration process.Furthermore,mature collagen infiltration and increased bone integration in vivo confirmed the promotion of tissue regeneration by the adaptive space,maintaining an excellent failure load of 67.65%of the native ligament at 16 weeks.This study proved the synergistic effects of dynamic strength and adaptive space.The scaffold matching the regeneration process is expected to open new approaches in ligament reconstruction.
基金The project is supported by the Fundamental Research Funds for the Central Universities(grant No.2232017A-05,2232019A3-06)Science and Technology Support Program of Shanghai(grant No.16441903803,18441902600)the Chinese Universities Scientific Fund(grant No.CUSF-DH-D-2017012)and 111 project(grant No.B07024).
文摘Recent progress in bioresorbable stents(BRSs)has provided a promising alternative for treating coronary artery disease.However,there is still lack of BRSs with satisfied compression and degradation performance for pediatric patients with congenital heart disease,leading to suboptimal therapy effects.Here,we developed a mechanically self-reinforced composite bioresorbable stent(cBRS)for congenital heart disease application.The cBRS consisted of poly(p-dioxanone)monofilaments and polycaprolactone/poly(p-dioxanone)core-shell composite yarns.Interlacing points in cBRS structure were partially bonded,offering the cBRS with significantly higher compression force compared to typical braids and remained good compliance.The suitable degradation profile of the cBRS can possibly preserve vascular remodeling and healing process.In addition,the controllable structural organization provides a method to customize the performance of the cBRS by altering the proportion of different components in the braids.The in vivo results suggested the cBRS supported the vessel wall similar to that of metallic stent.In both abdominal aorta and iliac artery of porcine,cBRS was entirely endothelialized within 1 month and maintained target vessels with good patency in the 12-month follow-up.The in vivo degradation profile of the cBRS is consistent with static degradation results in vitro.It is also demonstrated that there is minimal impact of pulsatile pressure of blood flow and variation of radial force on the degradation rate of the cBRS.Moreover,the lumen of cBRS implanted vessels were enlarged after 6 months,and significantly larger than the vessels implanted with metallic stent in 12 months.
基金support from the Natural Science Foundation of Shanghai (Grant No.21ZR1401300)the National Natural Science Foundation of China (Grant No.52005097)+4 种基金the Fundamental Research Funds for the Central Universities (2232022A-05)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University (CUSF-DH-D-2021022)the 111 Project (Grant No.BP0719035)the Fundamental Research Funds for DHU Distinguished Young Professor ProgramThe technical assistance of Jing。
文摘Stretchable conductive fibers have attracted much attention due to their potential use in wearable electronics.However,the ultrahigh strain insensitive conductivity is hindered by mechanical mismatch in Young’s modulus and failure of stretchable structures under large deformation.This challenge is addressed with a conductive and elastic multifilament made of the polyurethane monofilaments that are surface-coated with buckled polypyrrole(PPy)of which flexibility is improved by sodium sulfosalicylate.Such parallel conductive monofilaments with PPy buckling on surface reduce the influence of cracks in the conductive coating on the overall conductivity,displaying an ultra-high strain insensitive behavior(quality factor Q=10.9).Remarkably,various complex forms of wearable electronic textiles made by this conductive multifilament maintain the strain-insensitive behavior of the original multifilament,even upon the large deformation of human joint.This multifilament with wrinkled PPy has attractive advantages in the application of super-stretched wearable electronic devices.
基金the National Science Foundation for Young Scientists of China(No.81902556)the Fundamental Research Funds for the Central Universities(No.2232020G-01)+2 种基金the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D-2021019)China Scholarship Council(No.202006630061)111 Project(No.BP0719035).
文摘During the postoperative management of urinary diseases,oral or intravenous administration of drugs and implanting ureteral stents are usually required,making localized drug delivery by ureteral stent a precise and effective medication strategy.In the traditional drug loading method,the drug was premixed in the implants in production lines and the versatility of drugs was restricted.However,the complex situation in the urinary system fails the possibility of finding a“one fits all”medication plan,and the intraoperative drug-loading of implants is highly desired to support customized therapy.Here,we designed an ultrathin(8μm),elastic,and self-adhesive nanofiber bio-tape(NFBT)that can easily encapsulate drugs on the stent surface for controllable localized drug delivery.The NFBT exhibited high binding strength to a ureteral stent,a sustained release over 7 d in PBS for hydrophilic drug,and a zero-order release curve over 28 days for the hydrophobic drug nitrofurantoin(NFT).Further in vivo experiments using a porcine ureteral tract infection model demonstrated that NFBT loaded with NFT could significantly reduce the bacterial concentration in urine.The total amount of NFT delivered by the NFBT was about 2.68 wt%of the recommended dose for the systemic administration.
基金Supported by Shanghai Sailing Program(Grant No.20YF1400800)Shanghai Science and Technology Development Fund(21S31900700)111 Project 2.0(Grant no.BP0719035).
文摘Fibrosis is a common problem in soft tissue regeneration,often caused by the differentiation of fibroblasts into myofibro-blasts.Because of the nanoscale topology that regulates the mechanical transduction of cells,nanofibers or nanoparticles are commonly used to modulate fibroblast differentiation.However,the strength of nanofibers is insufficient,and the physi-ological toxicity of nanoparticles still remains to be verified.In this study,self-induced crystallization was used to construct nano-protrusions on the random and aligned polycaprolactone microfibers to regulate the behavior of fibroblasts.The results revealed that the mechanical properties of microfibers with a nanoscale topology were improved.Immunofluorescence staining manifested that nano-protrusions impeded the activation of integrins and vinculins,thereby inhibiting the nuclear transfer of Yes-associated protein,resulting in a decrease in the expression ofα-smooth muscle actin.Nanoscale topology of microfibers hampered the activation of the Rho/ROCK signalling pathway.In general,we used a simple process to con-struct a fibrous scaffold with a micro-nano multilevel structure.This structure can hinder the transformation of fibroblasts into myofibroblasts on both random and aligned fibers,which is expected to prevent fibrosis.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51479196,51179192,51139007)the Program for New Century Excellent Talents in University(NCET)(Grant No.NETC-10-0784).
文摘Lattice Boltzmannmodel(LBM)in conjunction with an accurate Large Eddy Simulation(LES)technology was proposed to simulate various vortical structures and their evolutions in open pump intakes.The strain rate tensor in the LES model is locally calculated by means of non-equilibrium moments based on Chapman-Enskog expansion,and bounce-back scheme was used for non-slip condition on solid walls and reflection scheme for free surface.The presentedmodel was applied to investigate free-surface and wall-attached vortices for different water levels and flow rate.The vortex position,shapes and vorticities were predicted successfully under three flowing cases(i.e.critical water level(CWL),lower water level,lower flow rate),and the numerical velocity and streamline distribution were analyzed systematically.For CWL based on Froude number considering open channel flows,the shape and the location of various dynamic vortices were captured.Compare to the experimental results of CWL,more vortices were predicted for lower water level,and less vortices were observed for lower flow rate.The predicted velocities and vortex locations are in good agreement with the experimental of a small physical model.The comparisons demonstrated the feasibility and stability of above-mentioned model and numerical method in predicting vortex flows inside open pump intakes.
