With the implementation of significant national strategies and rapid socioeconomic development,many ultra-long deep tunnels are being constructed in the Qinghai–Xizang Plateau region.However,the extreme complexity an...With the implementation of significant national strategies and rapid socioeconomic development,many ultra-long deep tunnels are being constructed in the Qinghai–Xizang Plateau region.However,the extreme complexity and variability of the environment in this region pose significant challenges to the safe construction and long-term operation of the planned or under-construction ultra-long deep tunnels.To address these complex technical challenges,this paper provides a detailed analysis of the complex climate and geology features of the Qinghai–Xizang Plateau during tunnel construction.The climate characteristics of the Qinghai–Xizang Plateau include severe coldness,low oxygen,and unpredictable weather changes.The geological characteristics include complex stress distributions caused by the intense internal and external dynamic coupling of tectonic plates,widespread active tectonic structures,frequent high-intensity earthquakes,fractured rock masses,and numerous active fault zones.Based on the analysis,this paper elaborates on potential sources of major disasters resulting from the characteristics of ultra-long deep tunnel projects in the Qinghai–Xizang Plateau region.These potential disaster sources include the crossing of active fault zones,high geostress rockbursts,large deformation disasters,high-pressure water surges,geothermal hazards,inadequate long-distance ventilation and oxygen supply,and multi-hazard couplings.In response to these challenges,this paper systematically summarizes the latest research progress and technological achievements in the domestic and international literature,and proposes innovative ideas and future development prospects for disaster monitoring and early warning,mechanized intelligent construction,long-term safety services,and emergency security and rescue.These innovative measures are intended to address the challenges of tunnel disaster prevention and control in the complex environment of the Qinghai–Xizang Plateau,contributing to the safe construction and long-term operation of ultra-long deep tunnels in this region.展开更多
Ultra-high molecular weight polyethylene(UHMWPE)is widely utilized in low-dimensional materials due to its ultra-long chain imparted excellent strength and modulus.By employing gel-molding technology with a gradient t...Ultra-high molecular weight polyethylene(UHMWPE)is widely utilized in low-dimensional materials due to its ultra-long chain imparted excellent strength and modulus.By employing gel-molding technology with a gradient temperature control,this study successfully produced gel films with varying shish crystal contents of the UHMWPE with a molecular weight of 8.0 million.The structural evolution during film hotstretching was investigated by in-situ wide-angle X-ray diffraction(WAXD),small-angle X-ray scattering(SAXS),ultra-small-angle X-ray scattering(USAXS),and ex-situ methods of scanning electron microscopy(SEM)and differential scanning calorimetry(DSC).The ultra-long molecular chains delay stress transfer during stretching but provide more nucleation sites for shish-kebab crystallization to form well-ordered shish-kebab crystals under high strain.The reserved high-content shish facilitates structural evolution,inducing the formation of highly-ordered shish-kebab crystals that eventually transfer into shish crystals in the later stage of stretching.The samples with low shish content,although the structural evolution is facilitated during stretching,predominantly result in newly formed shish-kebab crystals through melt recrystallization.However,some unoriented lamellae persists in unreserved samples stretching progress,leading to less ordered shish-kebab structures.By comparing with previous work of UHMWPE with low molecular weights,we demonstrate that the ultra-long molecular chains also play a key role on enabling the construction of highly-ordered shish-kebab crystals with high shish content during hot-stretching of UHMWPE gel films,providing new insights into processing control and optimization for engineering applications.展开更多
Lithium(Li)metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,the application of Li anode in re...Lithium(Li)metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,the application of Li anode in rechargeable Li metal batteries(LMBs)is hindered due to the short cycle life caused by uncontrolled dendrite growth.In this work,a dendrite-free anode(Li–Sn/Cu)is reinforced synergistically by lithophilic alloy,and a 3D grid structure is designed.Li^(+)diffusion and uniform nucleation are effectively induced by the lithophilic alloy Li_(22)Sn_(5).Moreover,homogeneous deposition of Li^(+)is caused by the reversible gridded Li plating/stripping effect of Cu mesh.Furthermore,the local space electric field is redistributed throughout the 3D conductive network,whereby the tip effect is suppressed,thus inhibiting the growth of Li dendrites.Also,the volume expansion of the anode during cycling is eased by the 3D grid structure.The results show that the Li–Sn/Cu symmetric battery can stably cycle for more than 10,000 h at 2 mA.cm^(-2)and 1 mAh.cm^(-2)with a low overpotential.The capacity retention of the LiFePO_(4)full battery remains above 90.7%after 1,000 cycles at 1C.This work provides a facile,low-cost,and effective strategy for obtaining Li metal batteries with ultra-long cycle life.展开更多
The ultra-long electromagnetic wave remote sensing technique developed by Peking University is one of new future techniques, which can detect the submarine geological information from the depth of 20 to 10000 m below ...The ultra-long electromagnetic wave remote sensing technique developed by Peking University is one of new future techniques, which can detect the submarine geological information from the depth of 20 to 10000 m below the surface by receiving natural ultra-long electromagnetic waves (n Hz to n 100 Hz). The new remote sensor is composed of three parts: a main instrument with a portable computer, an antenna with an amplifier and an external power.展开更多
Using Ti powder as reagent,ultra-long TiO2 nanofibers were prepared via hydrothermal method in NaOH solution.The samples were char-acterized respectively by means of field emission scanning electron microscopy (FESEM)...Using Ti powder as reagent,ultra-long TiO2 nanofibers were prepared via hydrothermal method in NaOH solution.The samples were char-acterized respectively by means of field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM) with selected area electron diffraction (SAED),and X-ray diffraction (XRD).The diameter and the length of the ultra-long TiO2 nanofiber were ～100 nm and >200μm,respectively.The ultra-long TiO2 nanofibers were anatase after heat treatment at 450 ?C for 1 h.Moreover,the optical properties of the products were investigated by UV-visible light absorption spectrum.Furthermore,methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens.Under the same testing conditions,the photocatalytic activity of the ultra-long TiO2 nanofibers was higher than that of P25.Direct electrical pathway and improved light-harvesting efficiency were crucial for the superior photocatalytic activity of the ultra-long TiO2 nanofibers.展开更多
A stability of a nonlinear ultra-long wave and its solution are discussed in this paper by employing Burger model which is subject to heat resource. It is of interest noted that the wave solution can be described by a...A stability of a nonlinear ultra-long wave and its solution are discussed in this paper by employing Burger model which is subject to heat resource. It is of interest noted that the wave solution can be described by an equation of KDV or MKDV and that conditions for the existence of the solution are related to characteristic divergences. In addition, a wave velocity expression for nonlinear ultra-long waves and some diagnostic correlations among wave parameters have been obtained.展开更多
The progress of zinc(Zn)metal batteries(ZMBs)is greatly limited by poor cycling stability because of the mutual restrictions of dendrite growth,corrosion reactions,and passivation.In this work,an ultralong lifespan(~7...The progress of zinc(Zn)metal batteries(ZMBs)is greatly limited by poor cycling stability because of the mutual restrictions of dendrite growth,corrosion reactions,and passivation.In this work,an ultralong lifespan(~7800 h),dendrite-free Zn metal anode is enabled via fabricating a functional hydrogel electrolyte out of polyacrylamide/graphene oxide(GO)/agarose(PGA)with a multifully cross-linked network.The synergetic integration of GO nanosheets and double-network structure endows the PGA hydrogel electrolyte with high ionic conductivity and excellent mechanical performance.More importantly,the abundant hydrophilic groups and stable three-dimensional cross-linked network of PGA electrolyte effectively constrain Zn^(2+)diffusion laterally along the Zn surface,which simultaneously prohibits waterinduced corrosion and thus significantly enhances Zn anode reversibility.Both theoretical simulations and experiments reveal that the PGA electrolyte is capable of optimizing de-solvation kinetics and harmonizing Zn^(2+)flux at the electrolyte-electrode interface,ensuring uniform Zn^(2+)deposition.Consequently,an ultra-long lifespan of 7800 h is achieved in the symmetric cell with the PGA electrolyte.Even at a high Zn utilization of 42.7%,it still delivers stable cycling over 1100 h.This work provides a practical and beneficial approach to dramatically extending the lifespan of the Zn anode and thus achieving high-performance ZMBs.展开更多
We develop a new electrospinning method to prepare ultra-long ordered La1-xSrxMnO3 （LSMO） nanowires. The length is up to several centimeters and is only limited by the size of the collector. The well-ordered straigh...We develop a new electrospinning method to prepare ultra-long ordered La1-xSrxMnO3 （LSMO） nanowires. The length is up to several centimeters and is only limited by the size of the collector. The well-ordered straight-line structure ensures the transport measurement, which is impossible to be carried out for the random nanowires fabricated by the traditional electrospinning method. Magnetic and transport measurements indicate that the physical properties of the LSMO nanowires depend sensitively on the doping concentration. At the optimum doping, the LSMO wires are ferromagnetic at room temperature with a metal-insulator transition temperature close to room temperature. Magnetic force microscopy studies are also performed to provide a microscopic view of these ultra-long nanowires.展开更多
Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the orig...Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing （RISC） from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials.展开更多
Transparent electrodes made of silver nanowires （AgNWs） exhibit higher flexibility when compared to those made of tin doped indium oxide （ITO） and are expected to be applied in plastic electronics. However, these ...Transparent electrodes made of silver nanowires （AgNWs） exhibit higher flexibility when compared to those made of tin doped indium oxide （ITO） and are expected to be applied in plastic electronics. However, these transparent electrodes composed of AgNWs show high haze because the wires cause strong light scattering in the visible range. Reduction of the wire diameter has been proposed as a way to weaken light scattering, although there have seldom been any studies focusing on the haze because of the difficulty involved in controlling the wire diameter. In this report, we show that the haze can be easily reduced by increasing the length of AgNWs with a large diameter. Ultra-long （u-long） AgNWs with lengths in the range of 20-100 μm and a maximum length of 230 μm have been successfully synthesized by adjusting the reaction temperature and the stirring speed of a one-step polyol process. Compared to typical AgNWs （with diameter and length of 70 nm and 10 μm, respectively） and ITO, a transparent electrode consisting of u-long AgNWs 91 nm in diameter demonstrated a low haze of 3.4%-1.6% and a low sheet resistance of 24-109 Ω/sq. at a transmittance of 94%-97%. Even when fabricated at room temperature without any post-treatment, the electrodes composed of u-long AgNWs achieved a sheet resistance of 19 Ω/sq, at a transmittance of 80%, which is six orders of magnitude lower than that of typical AgNWs.展开更多
The pursuit of complete telomere-to-telomere(T2T)genome assembly in plants,challenged by genomic complexity,has been advanced by Oxford Nanopore Technologies(ONT),which offers ultra-long,realtime sequencing.Despite it...The pursuit of complete telomere-to-telomere(T2T)genome assembly in plants,challenged by genomic complexity,has been advanced by Oxford Nanopore Technologies(ONT),which offers ultra-long,realtime sequencing.Despite its promise,sequencing length and gap filling remain significant challenges.This study optimized DNA extraction and library preparation,achieving DNA lengths exceeding 485 kb;average N50 read lengths of 80.57 kb,reaching up to 440 kb;and maximum reads of 5.83 Mb.Importantly,we demonstrated that combining ultra-long sequencing and adaptive sampling can effectively fill gaps during assembly,evidenced by successfully filling the remaining gaps of a near-complete Arabidopsis genome assembly and resolving the sequence of an unknown telomeric region in watermelon genome.Collectively,our strategies improve the feasibility of complete T2T genomic assemblies across various plant species,enhancing genome-based research in diverse fields.展开更多
Ultra-high-speed, ultra-large-capacity and ultra-long-haul （3U） are the forever pursuit of optical communication. As a new mode of optical communication, 3U transmission can greatly promote next generation optical i...Ultra-high-speed, ultra-large-capacity and ultra-long-haul （3U） are the forever pursuit of optical communication. As a new mode of optical communication, 3U transmission can greatly promote next generation optical internet and broadband mobile communication network development and technological progress, therefore it has become the focus of international high-tech intellectual property competition ground. This paper introduces the scientific problems, key technologies and important achievements in 3U transmission research.展开更多
In this paper, aiming at practical dense wavelength division multiplexing （DWDM） system with ultralong fiber span, a simple co-fiber remotely pumped erbium-doped fiber amplifier （RP-EDFA） scheme is proposed to ext...In this paper, aiming at practical dense wavelength division multiplexing （DWDM） system with ultralong fiber span, a simple co-fiber remotely pumped erbium-doped fiber amplifier （RP-EDFA） scheme is proposed to extend span distance with simple configuration and low pump power. Equivalent noise figure of -6 dB is achieved under 300-mW pump power. Using the experiment results, numerical simulation of ultra-long span systems shows that for a 40 × 11.6-Gb/s transmission system, the RP-EDFA scheme can support transmission of 1760 km with a fiber span of 160 km. These results demonstrate the potential of the PR-EDFA scheme in ultra-long span transmission.展开更多
With the expansion of tunnel construction scale,accurate modeling of 3D unsteady flow fields in ultra-long tunnels requires high computational resources.In this study,a resistance compensation method based on the St a...With the expansion of tunnel construction scale,accurate modeling of 3D unsteady flow fields in ultra-long tunnels requires high computational resources.In this study,a resistance compensation method based on the St and Eu similarity criterion is proposed to construct the simplified model to rapidly and precisely replicate the train-driven unstable airflow.A 6000 m ultra-long tunnel is utilized as a reference model and simplified models with the scale ratio varying from 80%to 10%are developed to assess the method performance.The multi-region dynamic mesh model is employed to simulate train tracking motion.After weighing the computational accuracy and efficiency,the results show that 20%is the optimal scale ratio.The unsteady wind speed of the simplified model deviates 6.96%from the reference model,while the simulation computation time is reduced by 85.01%.On this basis,the simplified model is applied to analyze the impacts of tunnel friction coefficients,blockage rates,train lengths and speeds,and departure intervals.The mean bias error(MBE)and Pearson correlation coefficient(PCC)are within 10%and over 0.8 respectively,confirming the reliability of the simplified model.The resistance compensation method is a crucial technique to improve the accuracy and efficiency of the unsteady flow field in ultra-long tunnels.展开更多
Objective:Overweight and obesity are increasingly epidemic and negatively related to reproductive outcome.The aim of this study was to investigate the advantages of a modified ultra-long downregulation protocol on pre...Objective:Overweight and obesity are increasingly epidemic and negatively related to reproductive outcome.The aim of this study was to investigate the advantages of a modified ultra-long downregulation protocol on pregnancy outcomes of patients with high body mass index(BMI)undergoingin vitro fertilization(IVF)/intracytoplasmic sperm injection(ICSI),compared to the long protocol(LP).Methods:We retrospectively analyzed the clinical data of 3,920 infertile patients at the Reproductive and Genetic Hospital of Citic-Xiangya from January 2012 to December 2017 by propensity score matching(PSM).Patients were divided into two groups:modified ultra-LP(MULP)(n=1,960)and LP(n=1,960).Results:In the MULP group,live birth rate(52.65%vs.46.79%,P<0.001,odds ratio[OR]:1.784,95%confidence interval[CI]:1.563-2.036),clinical pregnancy rate(62.50%vs.57.91%,P=0.003,OR:1.211,95%CI:1.066-1.377),and implantation rate(53.24%vs.49.65%,P=0.004,OR:1.155,95%CI:1.048-1.272)were statistically significantly higher than those of the LP group.Moreover,the cycle cancellation rates(12.70%vs.15.15%,P=0.027,OR:0.815,95%CI:0.68-0.977),abortion rates(12%vs.14.8%,P=0.046,OR:0.785,95%CI:0.619-0.996),and ectopic pregnancy rates(1.06%vs.2.11%,P=0.04,OR:0.497,95%CI:0.252-0.98)were lower than those in the LP group.Conclusion:The modified ultra-long downregulation protocol improved the pregnancy outcomes in patients with high BMI undergoing IVF/ICSI treatment,providing a potential option for physicians when deciding an optimized ovary stimulation protocol for high BMI patients.展开更多
文摘With the implementation of significant national strategies and rapid socioeconomic development,many ultra-long deep tunnels are being constructed in the Qinghai–Xizang Plateau region.However,the extreme complexity and variability of the environment in this region pose significant challenges to the safe construction and long-term operation of the planned or under-construction ultra-long deep tunnels.To address these complex technical challenges,this paper provides a detailed analysis of the complex climate and geology features of the Qinghai–Xizang Plateau during tunnel construction.The climate characteristics of the Qinghai–Xizang Plateau include severe coldness,low oxygen,and unpredictable weather changes.The geological characteristics include complex stress distributions caused by the intense internal and external dynamic coupling of tectonic plates,widespread active tectonic structures,frequent high-intensity earthquakes,fractured rock masses,and numerous active fault zones.Based on the analysis,this paper elaborates on potential sources of major disasters resulting from the characteristics of ultra-long deep tunnel projects in the Qinghai–Xizang Plateau region.These potential disaster sources include the crossing of active fault zones,high geostress rockbursts,large deformation disasters,high-pressure water surges,geothermal hazards,inadequate long-distance ventilation and oxygen supply,and multi-hazard couplings.In response to these challenges,this paper systematically summarizes the latest research progress and technological achievements in the domestic and international literature,and proposes innovative ideas and future development prospects for disaster monitoring and early warning,mechanized intelligent construction,long-term safety services,and emergency security and rescue.These innovative measures are intended to address the challenges of tunnel disaster prevention and control in the complex environment of the Qinghai–Xizang Plateau,contributing to the safe construction and long-term operation of ultra-long deep tunnels in this region.
基金supported by the National Natural Science Foundation of China(Nos.52173021,52373038 and 52073149)S&T Innovation 2025 Major Special Programme of Ningbo(No.2023Z079)。
文摘Ultra-high molecular weight polyethylene(UHMWPE)is widely utilized in low-dimensional materials due to its ultra-long chain imparted excellent strength and modulus.By employing gel-molding technology with a gradient temperature control,this study successfully produced gel films with varying shish crystal contents of the UHMWPE with a molecular weight of 8.0 million.The structural evolution during film hotstretching was investigated by in-situ wide-angle X-ray diffraction(WAXD),small-angle X-ray scattering(SAXS),ultra-small-angle X-ray scattering(USAXS),and ex-situ methods of scanning electron microscopy(SEM)and differential scanning calorimetry(DSC).The ultra-long molecular chains delay stress transfer during stretching but provide more nucleation sites for shish-kebab crystallization to form well-ordered shish-kebab crystals under high strain.The reserved high-content shish facilitates structural evolution,inducing the formation of highly-ordered shish-kebab crystals that eventually transfer into shish crystals in the later stage of stretching.The samples with low shish content,although the structural evolution is facilitated during stretching,predominantly result in newly formed shish-kebab crystals through melt recrystallization.However,some unoriented lamellae persists in unreserved samples stretching progress,leading to less ordered shish-kebab structures.By comparing with previous work of UHMWPE with low molecular weights,we demonstrate that the ultra-long molecular chains also play a key role on enabling the construction of highly-ordered shish-kebab crystals with high shish content during hot-stretching of UHMWPE gel films,providing new insights into processing control and optimization for engineering applications.
基金supported by the National Natural Science Foundation of China(No.52401221)Shandong Provincial Natural Science Foundation,China(No.ZR2022QE014)+1 种基金the Basic Scientific Research Fund for Central Universities(No.202112018)the Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education)。
文摘Lithium(Li)metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,the application of Li anode in rechargeable Li metal batteries(LMBs)is hindered due to the short cycle life caused by uncontrolled dendrite growth.In this work,a dendrite-free anode(Li–Sn/Cu)is reinforced synergistically by lithophilic alloy,and a 3D grid structure is designed.Li^(+)diffusion and uniform nucleation are effectively induced by the lithophilic alloy Li_(22)Sn_(5).Moreover,homogeneous deposition of Li^(+)is caused by the reversible gridded Li plating/stripping effect of Cu mesh.Furthermore,the local space electric field is redistributed throughout the 3D conductive network,whereby the tip effect is suppressed,thus inhibiting the growth of Li dendrites.Also,the volume expansion of the anode during cycling is eased by the 3D grid structure.The results show that the Li–Sn/Cu symmetric battery can stably cycle for more than 10,000 h at 2 mA.cm^(-2)and 1 mAh.cm^(-2)with a low overpotential.The capacity retention of the LiFePO_(4)full battery remains above 90.7%after 1,000 cycles at 1C.This work provides a facile,low-cost,and effective strategy for obtaining Li metal batteries with ultra-long cycle life.
文摘The ultra-long electromagnetic wave remote sensing technique developed by Peking University is one of new future techniques, which can detect the submarine geological information from the depth of 20 to 10000 m below the surface by receiving natural ultra-long electromagnetic waves (n Hz to n 100 Hz). The new remote sensor is composed of three parts: a main instrument with a portable computer, an antenna with an amplifier and an external power.
基金supported by Peak of Six Major Human Resources Plan of Jiangsu Province and Jiangsu Key Technology R&D Program (BE2009130)
文摘Using Ti powder as reagent,ultra-long TiO2 nanofibers were prepared via hydrothermal method in NaOH solution.The samples were char-acterized respectively by means of field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM) with selected area electron diffraction (SAED),and X-ray diffraction (XRD).The diameter and the length of the ultra-long TiO2 nanofiber were ～100 nm and >200μm,respectively.The ultra-long TiO2 nanofibers were anatase after heat treatment at 450 ?C for 1 h.Moreover,the optical properties of the products were investigated by UV-visible light absorption spectrum.Furthermore,methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens.Under the same testing conditions,the photocatalytic activity of the ultra-long TiO2 nanofibers was higher than that of P25.Direct electrical pathway and improved light-harvesting efficiency were crucial for the superior photocatalytic activity of the ultra-long TiO2 nanofibers.
文摘A stability of a nonlinear ultra-long wave and its solution are discussed in this paper by employing Burger model which is subject to heat resource. It is of interest noted that the wave solution can be described by an equation of KDV or MKDV and that conditions for the existence of the solution are related to characteristic divergences. In addition, a wave velocity expression for nonlinear ultra-long waves and some diagnostic correlations among wave parameters have been obtained.
基金supported by the National Key R&D Program of China(No.2020YFC1910200)the National Natural Science Foundation of China(Nos.51873011 and U1664251).
文摘The progress of zinc(Zn)metal batteries(ZMBs)is greatly limited by poor cycling stability because of the mutual restrictions of dendrite growth,corrosion reactions,and passivation.In this work,an ultralong lifespan(~7800 h),dendrite-free Zn metal anode is enabled via fabricating a functional hydrogel electrolyte out of polyacrylamide/graphene oxide(GO)/agarose(PGA)with a multifully cross-linked network.The synergetic integration of GO nanosheets and double-network structure endows the PGA hydrogel electrolyte with high ionic conductivity and excellent mechanical performance.More importantly,the abundant hydrophilic groups and stable three-dimensional cross-linked network of PGA electrolyte effectively constrain Zn^(2+)diffusion laterally along the Zn surface,which simultaneously prohibits waterinduced corrosion and thus significantly enhances Zn anode reversibility.Both theoretical simulations and experiments reveal that the PGA electrolyte is capable of optimizing de-solvation kinetics and harmonizing Zn^(2+)flux at the electrolyte-electrode interface,ensuring uniform Zn^(2+)deposition.Consequently,an ultra-long lifespan of 7800 h is achieved in the symmetric cell with the PGA electrolyte.Even at a high Zn utilization of 42.7%,it still delivers stable cycling over 1100 h.This work provides a practical and beneficial approach to dramatically extending the lifespan of the Zn anode and thus achieving high-performance ZMBs.
基金Supported by the National Basic Research Program of China under Grant Nos 2016YFA0300700,2013CB932901 and2014CB921104the National Natural Science Foundation of China under Grant Nos 11274071 and 11504053the Shanghai Municipal Natural Science Foundation under Grant No 11ZR140260
文摘We develop a new electrospinning method to prepare ultra-long ordered La1-xSrxMnO3 （LSMO） nanowires. The length is up to several centimeters and is only limited by the size of the collector. The well-ordered straight-line structure ensures the transport measurement, which is impossible to be carried out for the random nanowires fabricated by the traditional electrospinning method. Magnetic and transport measurements indicate that the physical properties of the LSMO nanowires depend sensitively on the doping concentration. At the optimum doping, the LSMO wires are ferromagnetic at room temperature with a metal-insulator transition temperature close to room temperature. Magnetic force microscopy studies are also performed to provide a microscopic view of these ultra-long nanowires.
基金The financial supports of the National Natural Science Foundation of China (grant nos. 21373042, 21677029 and 51402036)the Fundamental Research Funds for the Central Universities (grant no. DUT15YQ109)
文摘Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing （RISC） from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials.
文摘Transparent electrodes made of silver nanowires （AgNWs） exhibit higher flexibility when compared to those made of tin doped indium oxide （ITO） and are expected to be applied in plastic electronics. However, these transparent electrodes composed of AgNWs show high haze because the wires cause strong light scattering in the visible range. Reduction of the wire diameter has been proposed as a way to weaken light scattering, although there have seldom been any studies focusing on the haze because of the difficulty involved in controlling the wire diameter. In this report, we show that the haze can be easily reduced by increasing the length of AgNWs with a large diameter. Ultra-long （u-long） AgNWs with lengths in the range of 20-100 μm and a maximum length of 230 μm have been successfully synthesized by adjusting the reaction temperature and the stirring speed of a one-step polyol process. Compared to typical AgNWs （with diameter and length of 70 nm and 10 μm, respectively） and ITO, a transparent electrode consisting of u-long AgNWs 91 nm in diameter demonstrated a low haze of 3.4%-1.6% and a low sheet resistance of 24-109 Ω/sq. at a transmittance of 94%-97%. Even when fabricated at room temperature without any post-treatment, the electrodes composed of u-long AgNWs achieved a sheet resistance of 19 Ω/sq, at a transmittance of 80%, which is six orders of magnitude lower than that of typical AgNWs.
基金supported by the Key R&D Program of Shandong Province,China(grant no.ZR202211070163)the National Natural Science Foundation of China(grant nos.32170574 and 32200249)+1 种基金the Natural Science Foundation of Shandong Province(grant nos.ZR2023QC026 and ZR2023QC106)the Young Taishan Scholars Program and Yuandu Scholars Program.
文摘The pursuit of complete telomere-to-telomere(T2T)genome assembly in plants,challenged by genomic complexity,has been advanced by Oxford Nanopore Technologies(ONT),which offers ultra-long,realtime sequencing.Despite its promise,sequencing length and gap filling remain significant challenges.This study optimized DNA extraction and library preparation,achieving DNA lengths exceeding 485 kb;average N50 read lengths of 80.57 kb,reaching up to 440 kb;and maximum reads of 5.83 Mb.Importantly,we demonstrated that combining ultra-long sequencing and adaptive sampling can effectively fill gaps during assembly,evidenced by successfully filling the remaining gaps of a near-complete Arabidopsis genome assembly and resolving the sequence of an unknown telomeric region in watermelon genome.Collectively,our strategies improve the feasibility of complete T2T genomic assemblies across various plant species,enhancing genome-based research in diverse fields.
文摘Ultra-high-speed, ultra-large-capacity and ultra-long-haul （3U） are the forever pursuit of optical communication. As a new mode of optical communication, 3U transmission can greatly promote next generation optical internet and broadband mobile communication network development and technological progress, therefore it has become the focus of international high-tech intellectual property competition ground. This paper introduces the scientific problems, key technologies and important achievements in 3U transmission research.
文摘In this paper, aiming at practical dense wavelength division multiplexing （DWDM） system with ultralong fiber span, a simple co-fiber remotely pumped erbium-doped fiber amplifier （RP-EDFA） scheme is proposed to extend span distance with simple configuration and low pump power. Equivalent noise figure of -6 dB is achieved under 300-mW pump power. Using the experiment results, numerical simulation of ultra-long span systems shows that for a 40 × 11.6-Gb/s transmission system, the RP-EDFA scheme can support transmission of 1760 km with a fiber span of 160 km. These results demonstrate the potential of the PR-EDFA scheme in ultra-long span transmission.
基金supported by the Laboratory Basic Research Program of China State Railway Group Co.,Ltd.(L2021G011).
文摘With the expansion of tunnel construction scale,accurate modeling of 3D unsteady flow fields in ultra-long tunnels requires high computational resources.In this study,a resistance compensation method based on the St and Eu similarity criterion is proposed to construct the simplified model to rapidly and precisely replicate the train-driven unstable airflow.A 6000 m ultra-long tunnel is utilized as a reference model and simplified models with the scale ratio varying from 80%to 10%are developed to assess the method performance.The multi-region dynamic mesh model is employed to simulate train tracking motion.After weighing the computational accuracy and efficiency,the results show that 20%is the optimal scale ratio.The unsteady wind speed of the simplified model deviates 6.96%from the reference model,while the simulation computation time is reduced by 85.01%.On this basis,the simplified model is applied to analyze the impacts of tunnel friction coefficients,blockage rates,train lengths and speeds,and departure intervals.The mean bias error(MBE)and Pearson correlation coefficient(PCC)are within 10%and over 0.8 respectively,confirming the reliability of the simplified model.The resistance compensation method is a crucial technique to improve the accuracy and efficiency of the unsteady flow field in ultra-long tunnels.
基金support from the National Natural Science Foundation of China(grant No.81501328)。
文摘Objective:Overweight and obesity are increasingly epidemic and negatively related to reproductive outcome.The aim of this study was to investigate the advantages of a modified ultra-long downregulation protocol on pregnancy outcomes of patients with high body mass index(BMI)undergoingin vitro fertilization(IVF)/intracytoplasmic sperm injection(ICSI),compared to the long protocol(LP).Methods:We retrospectively analyzed the clinical data of 3,920 infertile patients at the Reproductive and Genetic Hospital of Citic-Xiangya from January 2012 to December 2017 by propensity score matching(PSM).Patients were divided into two groups:modified ultra-LP(MULP)(n=1,960)and LP(n=1,960).Results:In the MULP group,live birth rate(52.65%vs.46.79%,P<0.001,odds ratio[OR]:1.784,95%confidence interval[CI]:1.563-2.036),clinical pregnancy rate(62.50%vs.57.91%,P=0.003,OR:1.211,95%CI:1.066-1.377),and implantation rate(53.24%vs.49.65%,P=0.004,OR:1.155,95%CI:1.048-1.272)were statistically significantly higher than those of the LP group.Moreover,the cycle cancellation rates(12.70%vs.15.15%,P=0.027,OR:0.815,95%CI:0.68-0.977),abortion rates(12%vs.14.8%,P=0.046,OR:0.785,95%CI:0.619-0.996),and ectopic pregnancy rates(1.06%vs.2.11%,P=0.04,OR:0.497,95%CI:0.252-0.98)were lower than those in the LP group.Conclusion:The modified ultra-long downregulation protocol improved the pregnancy outcomes in patients with high BMI undergoing IVF/ICSI treatment,providing a potential option for physicians when deciding an optimized ovary stimulation protocol for high BMI patients.
