When the human society steps into a new epoch, we, in cooperation with the World Intellectual Property Organization (WIPO), hold the Sino-African Intellectual Property Forum, on which we may exchange experiences in de...When the human society steps into a new epoch, we, in cooperation with the World Intellectual Property Organization (WIPO), hold the Sino-African Intellectual Property Forum, on which we may exchange experiences in developing intellectual property systems and discuss issues of common concern. The themes listed in the agenda not only mirror the emerging issues of the development of the international intellectual property system, but also carry significant weight to展开更多
Dissipation, power due to the shear stress at the wall and the boundary layer thickness corresponding to the unsteady flow of a second grade fluid, due to a constantly accelerating plate, are established in exact and ...Dissipation, power due to the shear stress at the wall and the boundary layer thickness corresponding to the unsteady flow of a second grade fluid, due to a constantly accelerating plate, are established in exact and approximate forms. The changing of the kinetic energy with time is also determined from the energetic balance. Exact expressions of the same entities for Newtonian fluids are recovered as limiting cases of general results.展开更多
To say that China wool textile industry association released the"Twelfth Five-Year"excellent report,also have developed Chinese wool textile industry and opened a new situation that must lead the industry to...To say that China wool textile industry association released the"Twelfth Five-Year"excellent report,also have developed Chinese wool textile industry and opened a new situation that must lead the industry to achieve innovative development in next five years.In 12th Five-Year Program period,entire industry constantly formed the cooperation of industry with university,research and applying to promote the ability of innovation.There have been 41 science and tech-展开更多
CONSTANS,CO-like,and TOC1(CCT)family genes play important roles in regulating heading date,which exerts a large impact on the regional and seasonal adaptation of rice.Previous studies have shown that Grain number,plan...CONSTANS,CO-like,and TOC1(CCT)family genes play important roles in regulating heading date,which exerts a large impact on the regional and seasonal adaptation of rice.Previous studies have shown that Grain number,plant height,and heading date2(Ghd2)exhibits a negative response to drought stress by directly upregulating Rubisco activase and exerting a negative effect on heading date.However,the target gene of Ghd2 regulating heading date is still unknown.In this study,CO3 is identified by analyzing Ghd2 ChIP-seq data.Ghd2 activates CO3 expression by binding to the CO3 promoter through its CCT domain.EMSA experiments show that the motif CCACTA in the CO3 promoter was recognized by Ghd2.A comparison of the heading dates among plants with CO3 knocked out or overexpressed and double-mutants with Ghd2 overexpressed and CO3 knocked out shows that CO3 negatively and constantly regulates flowering by repressing the transcription of Ehd1,Hd3a,and RFT1.In addition,the target genes of CO3 are explored via a comprehensive analysis of DAP-seq and RNA-seq data.Taken together,these results suggest that Ghd2 directly binds to the downstream gene CO3,and the Ghd2eCO3 module constantly delays heading date via the Ehd1-mediated pathway.展开更多
The introduction of wireless capsule endoscopy has brought a revolutionary change in the diagnostic procedures for gastrointestinal disorders.Biopsy,an essential procedure for disease diagnosis,has been integrated int...The introduction of wireless capsule endoscopy has brought a revolutionary change in the diagnostic procedures for gastrointestinal disorders.Biopsy,an essential procedure for disease diagnosis,has been integrated into robotic capsule endoscopy to augment diagnostic capabilities.In this study,we propose a magnetically driven biopsy robot based on a Kresling origami.Considering the bistable properties of Krelsing origami and the elasticity of the creases,a foldable structure of the robot with constant force characteristics is designed.The folding motion of the structure is used to deploy the needle into the target tissue.The robot is capable of performing rolling motion under the control of an external magnetic drive system,and a fine needle biopsy technique is used to collect deep tissue samples.We also conduct in vitro rolling experiments and sampling experiments on apple tissues and pork tissues,which verify the performance of the robot.展开更多
Conductor materials with good mechanical performance as well as high electrical and thermal conductivities are particularly important to break through the current bottle-neck limit(~ 100 T) of pulsed magnets. Here, we...Conductor materials with good mechanical performance as well as high electrical and thermal conductivities are particularly important to break through the current bottle-neck limit(~ 100 T) of pulsed magnets. Here, we perform systematic studies on the elastic properties of the Cu–6wt% Ag alloy wire, which is a promising candidate material for the new-generation pulsed magnets, by employing two independent ultrasonic techniques, i.e., resonant ultrasound spectroscopy(RUS) and ultrasound pulse-echo experiments. Our RUS measurements manifest that the elastic properties of the Cu–6wt% Ag alloy wires can be improved by an electroplastic drawing procedure as compared with the conventional cold drawing. We also take this opportunity to test the availability of our newly-built ultrasound pulse-echo facility at the Wuhan National High Magnetic Field Center(WHMFC, China), and the results suggest that the elastic performance of the electroplastically-drawn Cu–6wt% Ag alloy wire remains excellent without anomalous softening under extreme conditions,e.g., in ultra-high magnetic field up to 50 T and nitrogen or helium cryogenic liquids.展开更多
A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that th...A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.展开更多
Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application o...Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.展开更多
With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences too...With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences took on a plurality of accelerator projects.Nevertheless,the stability of the coupler,a crucial system within the cavities of accelerators,has encountered certain difficulties.The alumina ceramics,which constitute the core component of the coupler,are increasingly prone to breakage and solder joint failures due to their inferior environmental adaptability,inadequate mechanical properties,and high gas emissions.Conversely,with the advancements in medical technology and materials science,zirconia ceramics have emerged as a prospective remedy for these problems.This type of ceramic is highly esteemed for its outstanding environmental adaptability,remarkable mechanical properties,and excellent high-temperature resistance,exhibiting extraordinary value in dental applications.This study investigates the use of zirconia ceramics in a 162.5 MHz 3-1/8"standard ceramic window,combining experimental data with finite element RF simulations and multi-physics analysis.A new coupler featuring a zirconia ceramic window was tested on a Quarter-Wave Resonator,demonstrating excellent alignment between electromagnetic simulations and measurement results.This reveals the substantial application potential and practical worth of the zirconia ceramic material in the context of accelerators.展开更多
The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclea...The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.展开更多
The management of patients with colorectal cancer(CRC)mainly lies on the use of magnetic resonance imaging(MRI)technique as a diagnostic tool for both staging and restaging.AIM To explore the preoperative value of qua...The management of patients with colorectal cancer(CRC)mainly lies on the use of magnetic resonance imaging(MRI)technique as a diagnostic tool for both staging and restaging.AIM To explore the preoperative value of quantitative parameters of dynamic contrastenhanced MRI(DCE-MRI)in evaluating clinical stages of CRC.METHODS A total of 86 CRC patients undergoing DCE-MRI examinations were included and then classified into CRC group(n=46)and benign tumor group(n=40)according to surgical and pathological results.Quantitative parameters of DCE-MRI,including volume transfer constant(Ktrans),rate constant(Kep)and extravascular extracellular volume fraction(Ve),were analyzed between two groups and among CRC at different stages.Receiver operating characteristic(ROC)curves with of quantitative parameters of DCE-MRI for clinical diagnosis and preoperative staging of CRC were plotted.RESULTS The CRC group had 9 cases with tumor in the upper segment,21 cases in the middle segment,16 in the low segment,10 cases with well differentiation,27 cases with moderate differentiation,and 9 cases with poor differentiation.The Ktrans,Kep,and Ve in the CRC group were higher than those in the benign tumor group(P<0.05).The ROC curves indicated that the optimal cutoff values of Ktrans,Kep and Ve for diagnosing CRC were 0.905 minute-1,0.225 minute-1 and 0.585%,respectively.The Ktrans,Kep and Ve as a combined tool to diagnose CRC yielded 0.863 of area under the curve and 82.60%of sensitivity,and both values were higher than those yielded by Ktrans,Kep,or Ve alone(P<0.05).The Ktrans,Kep and Ve in CRC patients at T3-T4 stage or N1-N2 stage were higher than those at T1-T2 stage or N0 stage(P<0.05).Results of Spearman correlation analysis showed that the Ktrans,Kep and Ve were correlated with advanced T and N stages in CRC patients(P<0.05).The ROC results indicated that the Ktrans produced a higher specificity(81.48%)and sensitivity(94.70%)in evaluating preoperative T stage of CRC.The Kep generated a higher specificity(96.00%)and sensitivity(81.00%)in evaluating preoperative N stage of CRC.CONCLUSION The study suggests that the values of Ktrans,Kep and Ve of DCE-MRI exhibit good performance in diagnosing CRC and preoperative assessment of clinical stages.However,relatively small sample size should be considered for data interpretation.展开更多
In this paper,we explicitly establish Poincaréinequality for 1≤p<∞ over simple geometric domains,such as segment,rectangle,triangle or tetrahedron.We obtain sharper bounds of the constant in Poincaré in...In this paper,we explicitly establish Poincaréinequality for 1≤p<∞ over simple geometric domains,such as segment,rectangle,triangle or tetrahedron.We obtain sharper bounds of the constant in Poincaré inequality and,in particular,the explicit relation between the constant and the geometric characters of the domain.展开更多
The Newtonian gravitational constant G is one of the most important fundamental constants of nature, but still remains resistant to the standard model of physics and disconnected from quantum theory. During the past &...The Newtonian gravitational constant G is one of the most important fundamental constants of nature, but still remains resistant to the standard model of physics and disconnected from quantum theory. During the past >100 years, hundreds of G values have been measured to be ranging around 6.66 to 6.7559 × 10−11 m3·kg−1·s−2 using macroscopic masses. More recently, however, a G value ((6.04 ± 0.06) × 10−11 m3·kg−1·s−2) measured using millimetre-sized masses shows significant deviation (by ~9%) from the reference G value, which the authors explained is resulted from “the known systematic uncertainties”. However, based on the observation of historical G values and the protocol of the millimetre-sized masses based experiment, here we proposed a theory that this deviation is not from “systematic uncertainties” but actually G will rapidly decrease when masses sphere diameter is less than 0.02 metres. Moreover, this theory predicted the G value will be 5.96 × 10−11 m3·kg−1·s−2 between masses whose diameter are 2 millimetres (0.002 metres), which matches the measured G value very well.展开更多
A fatal issue of Zn-based electrochemical energy storage is uneven Zn^(2+)deposition on the Zn metal anode.Unfortunately,the modulation for the inherent electric field,the origin of driving force for ion diffusion,has...A fatal issue of Zn-based electrochemical energy storage is uneven Zn^(2+)deposition on the Zn metal anode.Unfortunately,the modulation for the inherent electric field,the origin of driving force for ion diffusion,has been given insufficient importance.Herein,the redistribution of the surrounding electric field is demonstrated to depend on the permittivity of the surface medium for the first time,where highpermittivity particles can simultaneously enhance vertical components and reduce horizontal components of the electric field through polarization.Consequently,a bacterial cellulose-based separator is proposed by incorporating a high-permittivity surface medium.Cellulose serves as a robust substrate with a rather low thickness to enable homogeneous dispersion of high-permittivity particles on the surface,which can regulate the localized electric field to guide even Zn deposition by inhibiting twodimensional(2D)Zn^(2+)diffusion and suppressing side reactions by repulsing anion migration toward the Zn anode.The separator achieves significantly enhanced Zn anode stability of 2880 h at 1 mA cm^(-2)and a cumulative capacity of 3.5 Ah cm^(-2)at 10 mA cm^(-2).It also enables a long-term lifespan of 50,000 cycles in Zn||AC capacitor and 1000 cycles at a limited negative/positive(N/P)ratio of 3:1.This work provides a new view to stabilize Zn anode by electric field modulation.展开更多
There are limited quantitative studies on condensate gas using microfluidics under high-pressure and high-temperature conditions.This study employed microfluidics chips based on real porous media structures to conduct...There are limited quantitative studies on condensate gas using microfluidics under high-pressure and high-temperature conditions.This study employed microfluidics chips based on real porous media structures to conduct constant volume depletion experiments and investigate the microscopic mechanisms of condensate gas recovery.The aim of the experiments was to reveal the phase-behavior differences between bulk-phase gas and gas contained in porous media.The results revealed that condensate oil recovery in microfluidics experiments was higher than that in PVT cell tests,and nonuniform condensation and evaporation were exclusively observed in the microfluidics experiments.Furthermore,lower pore connectivity resulted in higher depletion recovery,while more developed fractures led to reduced recovery.Specifically,the chip with fewer fractures achieved the highest recovery(71.15%),whereas the highly fractured chip exhibited the lowest recovery(56.11%).These findings demonstrate that oil saturation during the process of constant volume depletion(CVD)of gas condensate within porous media is lower than that observed in the PVT cell,thus providing experimental evidence for optimizing condensate gas development in field applications.展开更多
To adapt to the trend of increasing miniaturization and high integration of microelectronic equipments,there is a high demand for multifunctional thermally conductive(TC)polymeric films combining excellent flame retar...To adapt to the trend of increasing miniaturization and high integration of microelectronic equipments,there is a high demand for multifunctional thermally conductive(TC)polymeric films combining excellent flame retardancy and low dielectric constant(ε).To date,there have been few successes that achieve such a performance portfolio in polymer films due to their different and even mutually exclusive governing mechanisms.Herein,we propose a trinity strategy for creating a rationally engineered heterostructure nanoadditive(FG@CuP@ZTC)by in situ self-assembly immobilization of copper-phenyl phosphonate(CuP)and zinc-3,5-diamino-1,2,4-triazole complex(ZTC)onto the fluorinated graphene(FG)surface.Benefiting from the synergistic effects of FG,CuP,and ZTC and the bionic lay-by-lay(LBL)strategy,the as-fabricated waterborne polyurethane(WPU)nanocomposite film with 30 wt%FG@CuP@ZTC exhibits a 55.6%improvement in limiting oxygen index(LOI),66.0%and 40.5%reductions in peak heat release rate and total heat release,respectively,and 93.3%increase in tensile strength relative to pure WPU film due to the synergistic effects between FG,CuP,and ZTC.Moreover,the WPU nanocomposite film presents a high thermal conductivity(λ)of 12.7 W m^(−1) K^(−1) and a lowεof 2.92 at 106 Hz.This work provides a commercially viable rational design strategy to develop high-performance multifunctional polymer nanocomposite films,which hold great potential as advanced polymeric thermal dissipators for high-power-density microelectronics.展开更多
Dielectric films are critical components in the fabrication of capacitors. However, their reliance on petroleum-derived polymers presents significant environmental challenges. To address this issue, we report on a hig...Dielectric films are critical components in the fabrication of capacitors. However, their reliance on petroleum-derived polymers presents significant environmental challenges. To address this issue, we report on a high-performance biomass-based dielectric material derived from vanillin(VA), a renewable aromatic aldehyde. Vanillin was first esterified to synthesize vanillin methacrylate(VMA), which was then copolymerized with methyl methacrylate(MMA) via free-radical polymerization to yield P(VMA-MMA). By crosslinking the aldehyde groups in VMA with the amine groups in the polyether amine D400(PEA), we fabricated a series of P(VMA-MMA)@PEA dielectric films with precisely tunable crosslinking densities. The unique molecular structure of vanillin, featuring both a benzene ring and an ester group, facilitates strong δ-π interactions and dipolar polarization, synergistically enhancing energy storage density while minimizing dielectric loss. At an optimal P(VMA-MMA) ratio of 1:10and 80% theoretical crosslinking degree, the dielectric constant reaches 3.4 at 10^(-3 )Hz, while the breakdown strength reaches 670.2 MV/m. Furthermore, the film exhibits an energy storage density of 7.1 J/cm3at 500 MV/m while maintaining a charge-discharge efficiency exceeding 90%.This study demonstrates a green and reliable strategy for designing biomass-based dielectric materials and opens new avenues for the development of eco-friendly energy-storage technologies.展开更多
In high-frequency electrical energy systems,polyimide(PI)composite insulation materials need to possess a low dielectric constant,sufficient thermal conductivity,and robust interfacial adhesion to ensure reliable perf...In high-frequency electrical energy systems,polyimide(PI)composite insulation materials need to possess a low dielectric constant,sufficient thermal conductivity,and robust interfacial adhesion to ensure reliable performance under elevated temperatures and pressures.These aspects are crucial for preventing local overheating and electrical breakdown,thereby ensuring reliable equipment operation.Traditional PI insulation materials often exhibit high dielectric constants and pronounced dielectric losses,compromising their insulation efficiency.In this study,molecular dynamics simulations were employed to incorporate polyhedral oligomeric silsesquioxanes(POSS)into PI through physical blending and chemical bonding to enhance dielectric properties.Key parameters of the PI/POSS composite system,including dielectric constant,thermal conductivity,glass transition temperature,Young’s modulus,Poisson’s ratio,and interfacial adhesion energy,were systematically evaluated for both doping methods.The degradation behavior of the PI composites under high-temperature and electric field conditions was also simulated to elucidate degradation pathways and product distributions,providing insights for designing low-dielectric insulation materials.Doping with POSS significantly reduces the dielectric constant of PI,thereby improving insulation performance,thermal stability,mechanical strength,and interfacial adhesion.At an optimal POSS doping ratio,the thermal conductivity of PI is enhanced.Compared with the physical blending system,the chemical bonding system yields more substantial improvements across all evaluated properties.Under high-temperature and strong electric field conditions,POSS doping enhances interfacial adhesion and thermal stability,effectively suppressing the cleavage of key chemical bonds,reducingCOemissions,and increasing the formation of oxygen-containing intermediates and water molecules,which contributes to improved environmental sustainability.展开更多
文摘When the human society steps into a new epoch, we, in cooperation with the World Intellectual Property Organization (WIPO), hold the Sino-African Intellectual Property Forum, on which we may exchange experiences in developing intellectual property systems and discuss issues of common concern. The themes listed in the agenda not only mirror the emerging issues of the development of the international intellectual property system, but also carry significant weight to
文摘Dissipation, power due to the shear stress at the wall and the boundary layer thickness corresponding to the unsteady flow of a second grade fluid, due to a constantly accelerating plate, are established in exact and approximate forms. The changing of the kinetic energy with time is also determined from the energetic balance. Exact expressions of the same entities for Newtonian fluids are recovered as limiting cases of general results.
文摘To say that China wool textile industry association released the"Twelfth Five-Year"excellent report,also have developed Chinese wool textile industry and opened a new situation that must lead the industry to achieve innovative development in next five years.In 12th Five-Year Program period,entire industry constantly formed the cooperation of industry with university,research and applying to promote the ability of innovation.There have been 41 science and tech-
基金supported by the Natural Science Foundation of China(U20A2031)the Earmarked Fund for China Agricultural Research System(CARS-01).
文摘CONSTANS,CO-like,and TOC1(CCT)family genes play important roles in regulating heading date,which exerts a large impact on the regional and seasonal adaptation of rice.Previous studies have shown that Grain number,plant height,and heading date2(Ghd2)exhibits a negative response to drought stress by directly upregulating Rubisco activase and exerting a negative effect on heading date.However,the target gene of Ghd2 regulating heading date is still unknown.In this study,CO3 is identified by analyzing Ghd2 ChIP-seq data.Ghd2 activates CO3 expression by binding to the CO3 promoter through its CCT domain.EMSA experiments show that the motif CCACTA in the CO3 promoter was recognized by Ghd2.A comparison of the heading dates among plants with CO3 knocked out or overexpressed and double-mutants with Ghd2 overexpressed and CO3 knocked out shows that CO3 negatively and constantly regulates flowering by repressing the transcription of Ehd1,Hd3a,and RFT1.In addition,the target genes of CO3 are explored via a comprehensive analysis of DAP-seq and RNA-seq data.Taken together,these results suggest that Ghd2 directly binds to the downstream gene CO3,and the Ghd2eCO3 module constantly delays heading date via the Ehd1-mediated pathway.
基金supported by the National Natural Science Foundation of China(Grant Nos.51805047 and 52175003)the Outstanding Youth Program of Hunan Education Department(Grant No.23B0335)the Natural Science Foundation of Hunan Province(Grant Nos.2023JJ30021 and 2023JJ50077).
文摘The introduction of wireless capsule endoscopy has brought a revolutionary change in the diagnostic procedures for gastrointestinal disorders.Biopsy,an essential procedure for disease diagnosis,has been integrated into robotic capsule endoscopy to augment diagnostic capabilities.In this study,we propose a magnetically driven biopsy robot based on a Kresling origami.Considering the bistable properties of Krelsing origami and the elasticity of the creases,a foldable structure of the robot with constant force characteristics is designed.The folding motion of the structure is used to deploy the needle into the target tissue.The robot is capable of performing rolling motion under the control of an external magnetic drive system,and a fine needle biopsy technique is used to collect deep tissue samples.We also conduct in vitro rolling experiments and sampling experiments on apple tissues and pork tissues,which verify the performance of the robot.
基金Project supported by the National Key R&D Program of China (Grant Nos. 2022YFA1602602 and 2023YFA1609600)the National Natural Science Foundation of China (Grant No. U23A20580)+3 种基金the open research fund of Songshan Lake Materials Laboratory (Grant No. 2022SLABFN27)Beijing National Laboratory for Condensed Matter Physics (Grant No. 2024BNLCMPKF004)Guangdong Basic and Applied Basic Research Foundation (Grant No. 2022B1515120020)the interdisciplinary program of Wuhan National High Magnetic Field Center at Huazhong University of Science and Technology (Grant No. WHMFC202132)。
文摘Conductor materials with good mechanical performance as well as high electrical and thermal conductivities are particularly important to break through the current bottle-neck limit(~ 100 T) of pulsed magnets. Here, we perform systematic studies on the elastic properties of the Cu–6wt% Ag alloy wire, which is a promising candidate material for the new-generation pulsed magnets, by employing two independent ultrasonic techniques, i.e., resonant ultrasound spectroscopy(RUS) and ultrasound pulse-echo experiments. Our RUS measurements manifest that the elastic properties of the Cu–6wt% Ag alloy wires can be improved by an electroplastic drawing procedure as compared with the conventional cold drawing. We also take this opportunity to test the availability of our newly-built ultrasound pulse-echo facility at the Wuhan National High Magnetic Field Center(WHMFC, China), and the results suggest that the elastic performance of the electroplastically-drawn Cu–6wt% Ag alloy wire remains excellent without anomalous softening under extreme conditions,e.g., in ultra-high magnetic field up to 50 T and nitrogen or helium cryogenic liquids.
基金financially supported by the National Natural Science Foundation of China(Grant No.42172292)Taishan Scholars Project Special Funding,and Shandong Energy Group(Grant No.SNKJ 2022A01-R26).
文摘A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.
基金Research and Development Project on Voltage Sensors by China Southern Power Grid Digital Research Institute(210000KK52220017)。
文摘Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.
文摘With rapid advancements in physics and particle medicine,the domestic accelerator industry has grown rapidly.During the 12th Five-Year Plan period,the Institute of Modern Physics of the Chinese Academy of Sciences took on a plurality of accelerator projects.Nevertheless,the stability of the coupler,a crucial system within the cavities of accelerators,has encountered certain difficulties.The alumina ceramics,which constitute the core component of the coupler,are increasingly prone to breakage and solder joint failures due to their inferior environmental adaptability,inadequate mechanical properties,and high gas emissions.Conversely,with the advancements in medical technology and materials science,zirconia ceramics have emerged as a prospective remedy for these problems.This type of ceramic is highly esteemed for its outstanding environmental adaptability,remarkable mechanical properties,and excellent high-temperature resistance,exhibiting extraordinary value in dental applications.This study investigates the use of zirconia ceramics in a 162.5 MHz 3-1/8"standard ceramic window,combining experimental data with finite element RF simulations and multi-physics analysis.A new coupler featuring a zirconia ceramic window was tested on a Quarter-Wave Resonator,demonstrating excellent alignment between electromagnetic simulations and measurement results.This reveals the substantial application potential and practical worth of the zirconia ceramic material in the context of accelerators.
基金National Natural Science Foundation of China(12135008,12132005)。
文摘The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.
文摘The management of patients with colorectal cancer(CRC)mainly lies on the use of magnetic resonance imaging(MRI)technique as a diagnostic tool for both staging and restaging.AIM To explore the preoperative value of quantitative parameters of dynamic contrastenhanced MRI(DCE-MRI)in evaluating clinical stages of CRC.METHODS A total of 86 CRC patients undergoing DCE-MRI examinations were included and then classified into CRC group(n=46)and benign tumor group(n=40)according to surgical and pathological results.Quantitative parameters of DCE-MRI,including volume transfer constant(Ktrans),rate constant(Kep)and extravascular extracellular volume fraction(Ve),were analyzed between two groups and among CRC at different stages.Receiver operating characteristic(ROC)curves with of quantitative parameters of DCE-MRI for clinical diagnosis and preoperative staging of CRC were plotted.RESULTS The CRC group had 9 cases with tumor in the upper segment,21 cases in the middle segment,16 in the low segment,10 cases with well differentiation,27 cases with moderate differentiation,and 9 cases with poor differentiation.The Ktrans,Kep,and Ve in the CRC group were higher than those in the benign tumor group(P<0.05).The ROC curves indicated that the optimal cutoff values of Ktrans,Kep and Ve for diagnosing CRC were 0.905 minute-1,0.225 minute-1 and 0.585%,respectively.The Ktrans,Kep and Ve as a combined tool to diagnose CRC yielded 0.863 of area under the curve and 82.60%of sensitivity,and both values were higher than those yielded by Ktrans,Kep,or Ve alone(P<0.05).The Ktrans,Kep and Ve in CRC patients at T3-T4 stage or N1-N2 stage were higher than those at T1-T2 stage or N0 stage(P<0.05).Results of Spearman correlation analysis showed that the Ktrans,Kep and Ve were correlated with advanced T and N stages in CRC patients(P<0.05).The ROC results indicated that the Ktrans produced a higher specificity(81.48%)and sensitivity(94.70%)in evaluating preoperative T stage of CRC.The Kep generated a higher specificity(96.00%)and sensitivity(81.00%)in evaluating preoperative N stage of CRC.CONCLUSION The study suggests that the values of Ktrans,Kep and Ve of DCE-MRI exhibit good performance in diagnosing CRC and preoperative assessment of clinical stages.However,relatively small sample size should be considered for data interpretation.
基金Supported by National Natural Science Foundation of China(Grant Nos.12001170 and 11601124)Innovative Funds Plan of Henan University of Technology(Grant No.2021ZKCJ11).
文摘In this paper,we explicitly establish Poincaréinequality for 1≤p<∞ over simple geometric domains,such as segment,rectangle,triangle or tetrahedron.We obtain sharper bounds of the constant in Poincaré inequality and,in particular,the explicit relation between the constant and the geometric characters of the domain.
文摘The Newtonian gravitational constant G is one of the most important fundamental constants of nature, but still remains resistant to the standard model of physics and disconnected from quantum theory. During the past >100 years, hundreds of G values have been measured to be ranging around 6.66 to 6.7559 × 10−11 m3·kg−1·s−2 using macroscopic masses. More recently, however, a G value ((6.04 ± 0.06) × 10−11 m3·kg−1·s−2) measured using millimetre-sized masses shows significant deviation (by ~9%) from the reference G value, which the authors explained is resulted from “the known systematic uncertainties”. However, based on the observation of historical G values and the protocol of the millimetre-sized masses based experiment, here we proposed a theory that this deviation is not from “systematic uncertainties” but actually G will rapidly decrease when masses sphere diameter is less than 0.02 metres. Moreover, this theory predicted the G value will be 5.96 × 10−11 m3·kg−1·s−2 between masses whose diameter are 2 millimetres (0.002 metres), which matches the measured G value very well.
基金financial support from the National Natural Science Foundation of China(NSFC No.52202253,ter for Microscopy and Analysis at the Nanjing University of Aero52372193,52472211,22293041)the Natural Science Foundation of Jiangsu Province(No.BK20220914)the Large Instrument and Equipment Sharing Fund of NUAA。
文摘A fatal issue of Zn-based electrochemical energy storage is uneven Zn^(2+)deposition on the Zn metal anode.Unfortunately,the modulation for the inherent electric field,the origin of driving force for ion diffusion,has been given insufficient importance.Herein,the redistribution of the surrounding electric field is demonstrated to depend on the permittivity of the surface medium for the first time,where highpermittivity particles can simultaneously enhance vertical components and reduce horizontal components of the electric field through polarization.Consequently,a bacterial cellulose-based separator is proposed by incorporating a high-permittivity surface medium.Cellulose serves as a robust substrate with a rather low thickness to enable homogeneous dispersion of high-permittivity particles on the surface,which can regulate the localized electric field to guide even Zn deposition by inhibiting twodimensional(2D)Zn^(2+)diffusion and suppressing side reactions by repulsing anion migration toward the Zn anode.The separator achieves significantly enhanced Zn anode stability of 2880 h at 1 mA cm^(-2)and a cumulative capacity of 3.5 Ah cm^(-2)at 10 mA cm^(-2).It also enables a long-term lifespan of 50,000 cycles in Zn||AC capacitor and 1000 cycles at a limited negative/positive(N/P)ratio of 3:1.This work provides a new view to stabilize Zn anode by electric field modulation.
基金supported by the National Natural Science Foundation of China(grant number 52404044).
文摘There are limited quantitative studies on condensate gas using microfluidics under high-pressure and high-temperature conditions.This study employed microfluidics chips based on real porous media structures to conduct constant volume depletion experiments and investigate the microscopic mechanisms of condensate gas recovery.The aim of the experiments was to reveal the phase-behavior differences between bulk-phase gas and gas contained in porous media.The results revealed that condensate oil recovery in microfluidics experiments was higher than that in PVT cell tests,and nonuniform condensation and evaporation were exclusively observed in the microfluidics experiments.Furthermore,lower pore connectivity resulted in higher depletion recovery,while more developed fractures led to reduced recovery.Specifically,the chip with fewer fractures achieved the highest recovery(71.15%),whereas the highly fractured chip exhibited the lowest recovery(56.11%).These findings demonstrate that oil saturation during the process of constant volume depletion(CVD)of gas condensate within porous media is lower than that observed in the PVT cell,thus providing experimental evidence for optimizing condensate gas development in field applications.
基金financially supported by the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20240372)China Postdoctoral Science Foundation(Grant No.2024M750728)+4 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2024ZB514)National Natural Science Foundation of China(Nos.21975185 and 51978239)Natural Science Foundation of Jiangsu Province(No.BK20220989)National Key R&D Program of China(Nos.2022YFC3203702 and 2023YFC3208900)the Australian Research Council(Nos.LP220100278,DP240102628 and DP240102728).
文摘To adapt to the trend of increasing miniaturization and high integration of microelectronic equipments,there is a high demand for multifunctional thermally conductive(TC)polymeric films combining excellent flame retardancy and low dielectric constant(ε).To date,there have been few successes that achieve such a performance portfolio in polymer films due to their different and even mutually exclusive governing mechanisms.Herein,we propose a trinity strategy for creating a rationally engineered heterostructure nanoadditive(FG@CuP@ZTC)by in situ self-assembly immobilization of copper-phenyl phosphonate(CuP)and zinc-3,5-diamino-1,2,4-triazole complex(ZTC)onto the fluorinated graphene(FG)surface.Benefiting from the synergistic effects of FG,CuP,and ZTC and the bionic lay-by-lay(LBL)strategy,the as-fabricated waterborne polyurethane(WPU)nanocomposite film with 30 wt%FG@CuP@ZTC exhibits a 55.6%improvement in limiting oxygen index(LOI),66.0%and 40.5%reductions in peak heat release rate and total heat release,respectively,and 93.3%increase in tensile strength relative to pure WPU film due to the synergistic effects between FG,CuP,and ZTC.Moreover,the WPU nanocomposite film presents a high thermal conductivity(λ)of 12.7 W m^(−1) K^(−1) and a lowεof 2.92 at 106 Hz.This work provides a commercially viable rational design strategy to develop high-performance multifunctional polymer nanocomposite films,which hold great potential as advanced polymeric thermal dissipators for high-power-density microelectronics.
基金supported by the National Natural Science Foundation of China(No.52203011).
文摘Dielectric films are critical components in the fabrication of capacitors. However, their reliance on petroleum-derived polymers presents significant environmental challenges. To address this issue, we report on a high-performance biomass-based dielectric material derived from vanillin(VA), a renewable aromatic aldehyde. Vanillin was first esterified to synthesize vanillin methacrylate(VMA), which was then copolymerized with methyl methacrylate(MMA) via free-radical polymerization to yield P(VMA-MMA). By crosslinking the aldehyde groups in VMA with the amine groups in the polyether amine D400(PEA), we fabricated a series of P(VMA-MMA)@PEA dielectric films with precisely tunable crosslinking densities. The unique molecular structure of vanillin, featuring both a benzene ring and an ester group, facilitates strong δ-π interactions and dipolar polarization, synergistically enhancing energy storage density while minimizing dielectric loss. At an optimal P(VMA-MMA) ratio of 1:10and 80% theoretical crosslinking degree, the dielectric constant reaches 3.4 at 10^(-3 )Hz, while the breakdown strength reaches 670.2 MV/m. Furthermore, the film exhibits an energy storage density of 7.1 J/cm3at 500 MV/m while maintaining a charge-discharge efficiency exceeding 90%.This study demonstrates a green and reliable strategy for designing biomass-based dielectric materials and opens new avenues for the development of eco-friendly energy-storage technologies.
基金financially supported by the Natural Science Foundation of Shandong Province(No.ZR2021ME011)State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(No.LAPS20001)。
文摘In high-frequency electrical energy systems,polyimide(PI)composite insulation materials need to possess a low dielectric constant,sufficient thermal conductivity,and robust interfacial adhesion to ensure reliable performance under elevated temperatures and pressures.These aspects are crucial for preventing local overheating and electrical breakdown,thereby ensuring reliable equipment operation.Traditional PI insulation materials often exhibit high dielectric constants and pronounced dielectric losses,compromising their insulation efficiency.In this study,molecular dynamics simulations were employed to incorporate polyhedral oligomeric silsesquioxanes(POSS)into PI through physical blending and chemical bonding to enhance dielectric properties.Key parameters of the PI/POSS composite system,including dielectric constant,thermal conductivity,glass transition temperature,Young’s modulus,Poisson’s ratio,and interfacial adhesion energy,were systematically evaluated for both doping methods.The degradation behavior of the PI composites under high-temperature and electric field conditions was also simulated to elucidate degradation pathways and product distributions,providing insights for designing low-dielectric insulation materials.Doping with POSS significantly reduces the dielectric constant of PI,thereby improving insulation performance,thermal stability,mechanical strength,and interfacial adhesion.At an optimal POSS doping ratio,the thermal conductivity of PI is enhanced.Compared with the physical blending system,the chemical bonding system yields more substantial improvements across all evaluated properties.Under high-temperature and strong electric field conditions,POSS doping enhances interfacial adhesion and thermal stability,effectively suppressing the cleavage of key chemical bonds,reducingCOemissions,and increasing the formation of oxygen-containing intermediates and water molecules,which contributes to improved environmental sustainability.
