The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab b...The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab ballastless track structure.This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects.Specimens were fabricated through on-site experiment.The percent of each area of 6 cm^(2)or more bubble defect was 0 in most of specimens.When the cumulative area of all bub-ble defects reached 12%,the splitting tensile strength value was 0.67 MPa,which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion.Furthermore,when the cumulative area of all bubble defects reached 8%,the splitting tensile strength value was 0.85 MPa,which exceeded the minimum required value of 0.8 MPa,thereby over-coming the negative impact of each area of 10 cm^(2) or more bubble defect.Additionally,keeping the cumulative area of each area of 6 cm^(2) or more bubble defect below 6%ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.展开更多
The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cool...The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cooling rates.The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions,feeding channel characteristics,and feeding capacity.Further,the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability.Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics.An increase in permeability corresponds to a declining number density of shrinkage porosities.This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.展开更多
In natural ecosystems,the timely abscission of seeds in wild plants is a crucial adaptive trait that contributes to reproductive success,population renewal,and colony expansion(Thurber et al.2010).In contrast,the tend...In natural ecosystems,the timely abscission of seeds in wild plants is a crucial adaptive trait that contributes to reproductive success,population renewal,and colony expansion(Thurber et al.2010).In contrast,the tendency for high seed shattering in domesticated crops,such as rice,not only reduces paddy yield but also complicates mechanized harvesting.展开更多
Designing anion-dominated weak solvation structures is often achieved by elevating the concentration of Li salts.However,this is accompanied by the increase in the cost.Herein,a medium concentration electrolyte (1 M) ...Designing anion-dominated weak solvation structures is often achieved by elevating the concentration of Li salts.However,this is accompanied by the increase in the cost.Herein,a medium concentration electrolyte (1 M) with weak solvation structures is established by the multi-anion strategy.Multiple anions in the electrolyte strengthen the anion-solvent interactions through stronger ion–dipole interactions.This reduces the quantity of free solvent and improves the reduction resistance of solvents.In addition,the Li ion–solvent interaction is weakened,facilitating the anions to enter the solvation sheaths of Li ions.This multi-anion-dominated weak solvation structures boost Li ion diffusion in the electrolyte,accelerate the desolvation process of Li ions,and induce inorganic-rich solid electrolyte interphase and uniform Li deposition.An average Coulombic efficiency of 99.1%for repeated Li plating/stripping can be achieved.Li||LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cells with a high cathode loading of 3.0 m A h cm^(-2) can maintain a capacity retention as high as 95% after 150 cycles.This finding provides novel standpoints to modulate the interaction of solvation structures and extend the lifespan of high-energy–density Li metal batteries.展开更多
Metal-support interactions and hydrogen spillover effects in heterogeneous catalysts play a crucial role in aromatic hydrogenation reactions;however,these effects are limited by the metal dispersion on the catalyst an...Metal-support interactions and hydrogen spillover effects in heterogeneous catalysts play a crucial role in aromatic hydrogenation reactions;however,these effects are limited by the metal dispersion on the catalyst and the number of acceptable H*receptors.This study prepares highly dispersed Ni nanoparticles(NPs)catalysts on a Beta substrate via precursor structure topology transformation.In contrast to traditional support materials,the coordination and electronic structure changes between the Ni NPs and the support were achieved,further optimizing the active interface sites and enhancing hydrogen activation and hydrogenation performance.Additionally,the-OH groups at the strong acid sites in zeolite effectively intensified the hydrogen spillover effect as receptors for H^(*)migration and anchoring,accelerating the hydrogenation rate of aromatic rings.Under solvent-free conditions,this catalyst was used for the hydrogenation reaction of aromatic-rich oils,directly producing a C_(8)-C_(14)branched cycloalkanes mixture with an aromatic conversion rate of>99%.The cycloalkanes mixture produced by this method features high density(0.92 g/mL)and a low freezing point(<-60℃),making it suitable for use as high-density aviation fuel or as an additive to enhance the volumetric heat value of conventional aviation fuels in practical applications.展开更多
The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers.At high temperatures,confining pressures,and geostress differences,rock has the mechanical characteristics o...The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers.At high temperatures,confining pressures,and geostress differences,rock has the mechanical characteristics of plastic enhancement,which leads to the unclear mechanism of hydraulic fracture expansion.The current fracturing model and construction design lack pertinence,and the fracturing reform is difficult to achieve the expected effect.This paper established a model of elastoplastic hydraulic fracture propagation in deep reservoirs.It considered the enhancement of plasticity by examining the elastoplastic deformation and nonlinear fracturing characteristics of the rock.The results confirmed that the hydraulic fractures in deep reservoirs propagated due to plastic energy dissipation after fracture tip passivation,while the stress concentration declined,which increased propagation resistance.The relationship between geology,engineering factors,degree of plasticity,and fracture propagation is discussed,while the conditions that promote fracture propagation are analyzed to provide theoretical support for deep reservoir fracturing design.展开更多
传统THz器件长期受限于衍射极限导致的辐射损耗,其品质因子(Q因子)普遍低于10~5,严重制约了通信与传感性能。针对这一技术瓶颈,本研究基于拓扑光子学理论,设计了一种具有C6v对称性的硅基超表面,在THz频段实现了拓扑保护的高Q因子谐振。...传统THz器件长期受限于衍射极限导致的辐射损耗,其品质因子(Q因子)普遍低于10~5,严重制约了通信与传感性能。针对这一技术瓶颈,本研究基于拓扑光子学理论,设计了一种具有C6v对称性的硅基超表面,在THz频段实现了拓扑保护的高Q因子谐振。通过构建三角形晶格光子晶体平板,在晶胞内引入圆柱型蚀刻孔实现对称性保护,并采用理想磁导体边界条件分离TE模式,将连续域束缚态(bound states in the continuum,BIC)的拓扑保护机制引入THz频段。结果显示,Γ点处Q因子达到1010量级,且BIC位于远场辐射的偏振涡旋中心,验证了BIC机制及其拓扑特性,仿真结果良好。最终实现的Q因子较传统器件提升了多个数量级,且拓扑保护机制可以显著抑制加工缺陷与环境扰动对谐振性能的影响,为低损耗通信器件、光学可编程技术与量子光源设计提供了新范式。展开更多
航空标准数据具有结构复杂、语义严谨和跨文档引用频繁等特点,为实现高效、精准的知识获取与问答应用带来挑战,本文提出一种面向航空标准的大语言模型(Large language models,LLMs)迭代检索增强生成(Retrieval-augmented generation,RAG...航空标准数据具有结构复杂、语义严谨和跨文档引用频繁等特点,为实现高效、精准的知识获取与问答应用带来挑战,本文提出一种面向航空标准的大语言模型(Large language models,LLMs)迭代检索增强生成(Retrieval-augmented generation,RAG)方法,设计了基于结构路径感知的标准向量知识库构建与检索机制,结合标准文档的章节结构与标题链条构建支持语境追溯的知识库,并提出基于关键词与语义融合的知识检索机制。在此基础上,设计LLM驱动的自动迭代检索与生成机制,使模型能够自主判断是否需要发起子问题拆解与深层意图识别,并结合多轮检索与动态调度策略,实现问题拆解、信息获取、自主判断与生成控制的一体化闭环,提升对多知识点聚合型、语义递进型等复杂标准问答任务的生成质量与覆盖深度。实验基于7459份航空标准文档构建知识库,针对500条专家标注问答对,在4类涵盖不同参数规模、模型类型及中英文语言能力的主流开源大语言模型上开展对比实验。结果表明,对于中大型参数规模的大模型,此方法在回答准确性、覆盖度和表达质量等指标上均显著优于传统方法。在大模型DeepSeek-R1-70B上,双语评估替补(Bilingual evaluation understudy,BLEU)指标平均提升27.97%,模拟主观评分提升7.99%;在大模型Qwen-2.5-32B上,BLEU指标平均提升54.67%,模拟主观评分提升8.58%。本文所提方法不仅适用于航空标准场景,也可推广至适航规章、维修手册等其他航空结构化文档场景,以及法律、医疗等对回答效果、可信度与可溯源性要求极高的领域,为相关问答系统的构建提供通用的技术框架与实现路径。展开更多
Lactulose is known to improve cognitive function in patients with early hepatic encephalopa- thy; however, the underlying mechanism remains poorly understood. In the present study, we investigated the behavioral and n...Lactulose is known to improve cognitive function in patients with early hepatic encephalopa- thy; however, the underlying mechanism remains poorly understood. In the present study, we investigated the behavioral and neurochemical effects of lactulose in a rat model of early hepatic encephalopathy induced by carbon tetrachloride. Immunohistochemistry showed that lactulose treatment promoted neurogenesis and increased the number of neurons and astrocytes in the hippocampus. Moreover, lactulose-treated rats showed shorter escape latencies than model rats in the Morris water maze, indicating that lactulose improved the cognitive impairments caused by hepatic encephalopathy. The present findings suggest that lactulose effectively improves cog- nitive function by enhancing neuroplasticity in a rat model of early hepatic encephalopathy.展开更多
OBJECTIVE:To investigate the effectiveness of electroacupuncture at Jiaji acupoints(EX-B 2)plus moxibustion and intermediate frequency on postherpetic neuralgia(PHN).METHODS:A total of 140 outpatients who satisfied th...OBJECTIVE:To investigate the effectiveness of electroacupuncture at Jiaji acupoints(EX-B 2)plus moxibustion and intermediate frequency on postherpetic neuralgia(PHN).METHODS:A total of 140 outpatients who satisfied the inclusion criteria and volunteered for this treatment were randomly divided into treatment(n=70)and control(n=70)groups.Both groups received a localized lesion area and electroacupuncture treatment combined with moxibustion and intermediate frequency.The treatment group(TG)increased acupuncture at Jiaji acupoints(EX-B 2)and electroacupuncture.Pain and anxiety were assessed before and after 5,10,15,and 20 treatments by using visual pain simulation score(VAS)and Hamilton anxiety scale(HAMA),respectively.Clinical efficacy was also evaluated.RESULTS:The baseline between the two groups did not significantly differ(P>0.05).The VAS and HAMA scores of the two groups after treatment significantly decreased compared with those of various treatment stages(P>0.05).The HAMA score(P<0.01)of TG was lower than that of the control group(CG).The VAS score of TG was lower than that of CG in the 5th and 10th treatments(P<0.01).In the 15 th and 10 th scores,CG was also superior to TG(P<0.05).CONCLUSION:The combined treatment of electroacupuncture at Jiaji acupoints(EX-B 2),moxibustion,and intermediate frequency can relieve the pain and anxiety symptoms of PHN.The efficacy of the combined treatment was superior to traditional acupuncture.展开更多
Gene therapy is one of the most attractive fields in tumor therapy. In past decades, significant progress has been achieved. Various approaches, such as viral and non-viral vectors and physical methods, have been deve...Gene therapy is one of the most attractive fields in tumor therapy. In past decades, significant progress has been achieved. Various approaches, such as viral and non-viral vectors and physical methods, have been developed to make gene delivery safer and more efficient. Several therapeutic strategies have evolved, including gene-based (tumor suppressor genes, suicide genes, antiangiogenic genes, cytokine and oxidative stress-based genes) and RNA-based (antisense oligonucleotides and RNA interference) approaches. In addition, immune response-based strategies (dendritic cell- and T cell-based therapy) are also under investigation in tumor gene therapy. This review highlights the progress and recent developments in gene delivery systems, therapeutic strategies, and possible clinical directions for gene therapy.展开更多
The clay mineral content of Daqing Gulong shale is in the range of about 35%–45%,with particle sizes less than 0.0039 mm.The horizontal fluidity of oil in Gulong shale is poor,with near-zero vertical flowability.As a...The clay mineral content of Daqing Gulong shale is in the range of about 35%–45%,with particle sizes less than 0.0039 mm.The horizontal fluidity of oil in Gulong shale is poor,with near-zero vertical flowability.As a result,Gulong shale has been considered to lack commercial value.In recent years,however,interdisciplinary research in geoscience,percolation mechanics,thermodynamics,and surface mechanics has demonstrated that Gulong shale oil has a high degree of maturity and a high residual hydrocarbon content.The expulsion efficiency of Gulong shale in the high mature stage is 32%–48%.Favorable storage spaces in Gulong shale include connecting pores and lamellar fractures developed between and within organic matter and clay mineral complexes.The shale oil mainly occurs in micro-and nano-pores,bedding fractures,and lamellar fractures,with a high gas–oil ratio and medium–high movable oil saturation.Gulong shale has the characteristics of high hardness,a high elastic modulus,and high fracture toughness.This study achieves breakthroughs in the exploration and development of Gulong shale,including the theories of hydrocarbon generation and accumulation,the technologies of mobility and fracturing,and recoverability.It confirms the major transition of Gulong shale from oil generation to oil production,which has extremely significant scientific value and application potential for China’s petroleum industry.展开更多
Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive a...Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive amount of resources and the rapid growth of proven geological reserves.The challenges of technology,cost,management,and methodology restrict large-scale and economic development.Based on successful practices,a"one engine with six gears"system engineering methodology is put forward,which includes life-cycle management,overall synergy,interdisciplinary cross-service integration,marketoriented operation,socialized support,digitalized management,and low-carbon and green development.The methodology has been proved to be effective in multiple unconventional oil and gas national demonstration areas,including the Jimusar continental shale oil demonstration area.Disruptive views are introduced-namely,that unconventional oil and gas do not necessarily yield a low return,nor do they necessarily have a low recovery factor.A determination to achieve economic benefit must be a pervasive underlying goal for managers and experts.Return and recovery factors,as primary focuses,must be adhered to during China’s development of unconventional oil and gas.The required methodology transformation includes a revolution in management systems to significantly decrease cost and increase production,resulting in technological innovation.展开更多
Lithium(Li) metal anode has received extensive attentions due to its ultrahigh theoretical capacity and the most negative electrode potential. However, dendrite growth severely impedes the practical applications of th...Lithium(Li) metal anode has received extensive attentions due to its ultrahigh theoretical capacity and the most negative electrode potential. However, dendrite growth severely impedes the practical applications of the Li metal anode in rechargeable batteries. In this contribution, a mesoporous graphene with a high specific surface area was synthesized to host the Li metal anode. The mesoporous graphene host(MGH) has a high specific surface area(2090 m^2/g), which affords free space and an interconnected conductive pathway for Li plating and stripping, thus alleviating the volume variation and reducing the generation of dead Li during repeated cycles. More importantly, the high specific surface area of MGH efficiently reduces the local current density of the electrode, which favors a uniform Li nucleation and plating behavior, rendering a dendritefree deposition morphology at a low overpotential. These factors synergistically boost the Li utilization(90.1% vs. 70.1% for Cu foil) and life span(150 cycles vs. 100 cycles for Cu foil) with a low polarization of MGH electrode at an ultrahigh current of 15.0 mA/cm^2. The as-prepared MGH can provide fresh insights into the electrode design of the Li metal anode operating at high rates.展开更多
A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. T...A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. Thermal cycling behavior of NiCoCrAlY-4 YSZ thermal barrier coatings(TBCs) with and without Pt modification was evaluated in ambient air at 1100?C up to 1000 cycles, aiming to investigate the effect of Pt on formation of thermally grown oxide(TGO) and oxidation resistance. Results indicated that a dual layered TGO, which consisted of top(Ni,Co)(Cr,Al)_2O_4 spinel and underlying α-Al_2O_3, was formed at the NiCoCrAlY/4 YSZ interface with thickness of 8.4μm, accompanying with visible cracks at the interface. In contrast, a single-layer and adherent α-Al_2O_3 scale with thickness of 5.6μm was formed at the interface of Pt-modified NiCoCrAlY and 4 YSZ top coating. The modification of Pt on NiCoCrAlY favored the exclusive formation of α-Al_2O_3 and the reduction of TGO growth rate, and thus could effectively improve overall oxidation performance and extend service life of TBCs. Oxidation and degradation mechanisms of the TBCs with/without Pt-modification were discussed.展开更多
基金supported by a grant from China railway corporation science and technology research and development plan project(Grant No.2017G005-B)funding support by Wuyi University’s Hong Kong and Macao Joint Research and Development Fund(Grants No.2021WGALH15)funding support by the Innovation and Technology Commission of Hong Kong SAR Government to the Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center(Grant No.K-BBY1).
文摘The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab ballastless track structure.This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects.Specimens were fabricated through on-site experiment.The percent of each area of 6 cm^(2)or more bubble defect was 0 in most of specimens.When the cumulative area of all bub-ble defects reached 12%,the splitting tensile strength value was 0.67 MPa,which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion.Furthermore,when the cumulative area of all bubble defects reached 8%,the splitting tensile strength value was 0.85 MPa,which exceeded the minimum required value of 0.8 MPa,thereby over-coming the negative impact of each area of 10 cm^(2) or more bubble defect.Additionally,keeping the cumulative area of each area of 6 cm^(2) or more bubble defect below 6%ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3701000)the National Natural Science Foundation of China(Nos.52471118,52101125,U2037601,and U21A2048)Young Elite Scientists Sponsorship Program by CAST,China(No.2022QNRC001)。
文摘The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cooling rates.The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions,feeding channel characteristics,and feeding capacity.Further,the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability.Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics.An increase in permeability corresponds to a declining number density of shrinkage porosities.This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.
基金supported by the National Natural Science Foundation of China(32372118 and 32188102)the Qian Qian Academician Workstation,China+3 种基金the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province,China(YSPTZX202303)the Nanfan Special Project,Chinese Academy of Agricultural Sciences(ZDXM2315)the Chinese Academy of Agricultural Sciences Talent Plan-Outstanding Young Talentthe Zhejiang Province’s High-level Talent Special Support Plan-Young Talent,China。
文摘In natural ecosystems,the timely abscission of seeds in wild plants is a crucial adaptive trait that contributes to reproductive success,population renewal,and colony expansion(Thurber et al.2010).In contrast,the tendency for high seed shattering in domesticated crops,such as rice,not only reduces paddy yield but also complicates mechanized harvesting.
基金funded by National Natural Science Foundation of China (22379072, 92372111, 22179070)the Startup Foundation for Introducing Talent of NUIST (2022r038)+1 种基金the Jiangsu Specially Appointed Professor Program, the Natural Science Foundation of Jiangsu Province (BK20220073)the Fundamental Research Funds for the Central Universities (RF1028623157)。
文摘Designing anion-dominated weak solvation structures is often achieved by elevating the concentration of Li salts.However,this is accompanied by the increase in the cost.Herein,a medium concentration electrolyte (1 M) with weak solvation structures is established by the multi-anion strategy.Multiple anions in the electrolyte strengthen the anion-solvent interactions through stronger ion–dipole interactions.This reduces the quantity of free solvent and improves the reduction resistance of solvents.In addition,the Li ion–solvent interaction is weakened,facilitating the anions to enter the solvation sheaths of Li ions.This multi-anion-dominated weak solvation structures boost Li ion diffusion in the electrolyte,accelerate the desolvation process of Li ions,and induce inorganic-rich solid electrolyte interphase and uniform Li deposition.An average Coulombic efficiency of 99.1%for repeated Li plating/stripping can be achieved.Li||LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cells with a high cathode loading of 3.0 m A h cm^(-2) can maintain a capacity retention as high as 95% after 150 cycles.This finding provides novel standpoints to modulate the interaction of solvation structures and extend the lifespan of high-energy–density Li metal batteries.
基金financially supported by the National Natural Science Foundation of China(Grant 22278439,21776313)the Shandong Province Higher Education Youth Innovation Technology Support Program(Grant 2022KJ074)。
文摘Metal-support interactions and hydrogen spillover effects in heterogeneous catalysts play a crucial role in aromatic hydrogenation reactions;however,these effects are limited by the metal dispersion on the catalyst and the number of acceptable H*receptors.This study prepares highly dispersed Ni nanoparticles(NPs)catalysts on a Beta substrate via precursor structure topology transformation.In contrast to traditional support materials,the coordination and electronic structure changes between the Ni NPs and the support were achieved,further optimizing the active interface sites and enhancing hydrogen activation and hydrogenation performance.Additionally,the-OH groups at the strong acid sites in zeolite effectively intensified the hydrogen spillover effect as receptors for H^(*)migration and anchoring,accelerating the hydrogenation rate of aromatic rings.Under solvent-free conditions,this catalyst was used for the hydrogenation reaction of aromatic-rich oils,directly producing a C_(8)-C_(14)branched cycloalkanes mixture with an aromatic conversion rate of>99%.The cycloalkanes mixture produced by this method features high density(0.92 g/mL)and a low freezing point(<-60℃),making it suitable for use as high-density aviation fuel or as an additive to enhance the volumetric heat value of conventional aviation fuels in practical applications.
基金The Youth Science Fund Project of National Natural Science Foundation of China,52404027,Jinbo Lithe General Program of the National Natural Science Foundation of China,52274036,Suling Wang。
文摘The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers.At high temperatures,confining pressures,and geostress differences,rock has the mechanical characteristics of plastic enhancement,which leads to the unclear mechanism of hydraulic fracture expansion.The current fracturing model and construction design lack pertinence,and the fracturing reform is difficult to achieve the expected effect.This paper established a model of elastoplastic hydraulic fracture propagation in deep reservoirs.It considered the enhancement of plasticity by examining the elastoplastic deformation and nonlinear fracturing characteristics of the rock.The results confirmed that the hydraulic fractures in deep reservoirs propagated due to plastic energy dissipation after fracture tip passivation,while the stress concentration declined,which increased propagation resistance.The relationship between geology,engineering factors,degree of plasticity,and fracture propagation is discussed,while the conditions that promote fracture propagation are analyzed to provide theoretical support for deep reservoir fracturing design.
文摘传统THz器件长期受限于衍射极限导致的辐射损耗,其品质因子(Q因子)普遍低于10~5,严重制约了通信与传感性能。针对这一技术瓶颈,本研究基于拓扑光子学理论,设计了一种具有C6v对称性的硅基超表面,在THz频段实现了拓扑保护的高Q因子谐振。通过构建三角形晶格光子晶体平板,在晶胞内引入圆柱型蚀刻孔实现对称性保护,并采用理想磁导体边界条件分离TE模式,将连续域束缚态(bound states in the continuum,BIC)的拓扑保护机制引入THz频段。结果显示,Γ点处Q因子达到1010量级,且BIC位于远场辐射的偏振涡旋中心,验证了BIC机制及其拓扑特性,仿真结果良好。最终实现的Q因子较传统器件提升了多个数量级,且拓扑保护机制可以显著抑制加工缺陷与环境扰动对谐振性能的影响,为低损耗通信器件、光学可编程技术与量子光源设计提供了新范式。
基金supported by a grant from the National Natural Science Foundation of China,No.30873390
文摘Lactulose is known to improve cognitive function in patients with early hepatic encephalopa- thy; however, the underlying mechanism remains poorly understood. In the present study, we investigated the behavioral and neurochemical effects of lactulose in a rat model of early hepatic encephalopathy induced by carbon tetrachloride. Immunohistochemistry showed that lactulose treatment promoted neurogenesis and increased the number of neurons and astrocytes in the hippocampus. Moreover, lactulose-treated rats showed shorter escape latencies than model rats in the Morris water maze, indicating that lactulose improved the cognitive impairments caused by hepatic encephalopathy. The present findings suggest that lactulose effectively improves cog- nitive function by enhancing neuroplasticity in a rat model of early hepatic encephalopathy.
文摘OBJECTIVE:To investigate the effectiveness of electroacupuncture at Jiaji acupoints(EX-B 2)plus moxibustion and intermediate frequency on postherpetic neuralgia(PHN).METHODS:A total of 140 outpatients who satisfied the inclusion criteria and volunteered for this treatment were randomly divided into treatment(n=70)and control(n=70)groups.Both groups received a localized lesion area and electroacupuncture treatment combined with moxibustion and intermediate frequency.The treatment group(TG)increased acupuncture at Jiaji acupoints(EX-B 2)and electroacupuncture.Pain and anxiety were assessed before and after 5,10,15,and 20 treatments by using visual pain simulation score(VAS)and Hamilton anxiety scale(HAMA),respectively.Clinical efficacy was also evaluated.RESULTS:The baseline between the two groups did not significantly differ(P>0.05).The VAS and HAMA scores of the two groups after treatment significantly decreased compared with those of various treatment stages(P>0.05).The HAMA score(P<0.01)of TG was lower than that of the control group(CG).The VAS score of TG was lower than that of CG in the 5th and 10th treatments(P<0.01).In the 15 th and 10 th scores,CG was also superior to TG(P<0.05).CONCLUSION:The combined treatment of electroacupuncture at Jiaji acupoints(EX-B 2),moxibustion,and intermediate frequency can relieve the pain and anxiety symptoms of PHN.The efficacy of the combined treatment was superior to traditional acupuncture.
基金supported by Foundation from Knowl edge Innovation Program in CAS (No. KSCX1-YW-R-10)National Natural Science Foundation of China(No. 30973448)
文摘Gene therapy is one of the most attractive fields in tumor therapy. In past decades, significant progress has been achieved. Various approaches, such as viral and non-viral vectors and physical methods, have been developed to make gene delivery safer and more efficient. Several therapeutic strategies have evolved, including gene-based (tumor suppressor genes, suicide genes, antiangiogenic genes, cytokine and oxidative stress-based genes) and RNA-based (antisense oligonucleotides and RNA interference) approaches. In addition, immune response-based strategies (dendritic cell- and T cell-based therapy) are also under investigation in tumor gene therapy. This review highlights the progress and recent developments in gene delivery systems, therapeutic strategies, and possible clinical directions for gene therapy.
基金supported by the National Natural Science Foundation of China(72088101 and 42090025)the China National Petroleum Corporation(2019E-26 and YGJ2020-3)。
文摘The clay mineral content of Daqing Gulong shale is in the range of about 35%–45%,with particle sizes less than 0.0039 mm.The horizontal fluidity of oil in Gulong shale is poor,with near-zero vertical flowability.As a result,Gulong shale has been considered to lack commercial value.In recent years,however,interdisciplinary research in geoscience,percolation mechanics,thermodynamics,and surface mechanics has demonstrated that Gulong shale oil has a high degree of maturity and a high residual hydrocarbon content.The expulsion efficiency of Gulong shale in the high mature stage is 32%–48%.Favorable storage spaces in Gulong shale include connecting pores and lamellar fractures developed between and within organic matter and clay mineral complexes.The shale oil mainly occurs in micro-and nano-pores,bedding fractures,and lamellar fractures,with a high gas–oil ratio and medium–high movable oil saturation.Gulong shale has the characteristics of high hardness,a high elastic modulus,and high fracture toughness.This study achieves breakthroughs in the exploration and development of Gulong shale,including the theories of hydrocarbon generation and accumulation,the technologies of mobility and fracturing,and recoverability.It confirms the major transition of Gulong shale from oil generation to oil production,which has extremely significant scientific value and application potential for China’s petroleum industry.
基金supported by the Project of Basic Science Center for the National Natural Science Foundation of China(72088101)。
文摘Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive amount of resources and the rapid growth of proven geological reserves.The challenges of technology,cost,management,and methodology restrict large-scale and economic development.Based on successful practices,a"one engine with six gears"system engineering methodology is put forward,which includes life-cycle management,overall synergy,interdisciplinary cross-service integration,marketoriented operation,socialized support,digitalized management,and low-carbon and green development.The methodology has been proved to be effective in multiple unconventional oil and gas national demonstration areas,including the Jimusar continental shale oil demonstration area.Disruptive views are introduced-namely,that unconventional oil and gas do not necessarily yield a low return,nor do they necessarily have a low recovery factor.A determination to achieve economic benefit must be a pervasive underlying goal for managers and experts.Return and recovery factors,as primary focuses,must be adhered to during China’s development of unconventional oil and gas.The required methodology transformation includes a revolution in management systems to significantly decrease cost and increase production,resulting in technological innovation.
基金supported by the National Key Research and Development Program (Nos. 2016YFA0202500 and 2016YFA0200102)National Natural Science Foundation of China (Nos. 21676160, 21825501, 21805161, 21808121, and U1801257)the Tsinghua University Initiative Scientific Research Program.
文摘Lithium(Li) metal anode has received extensive attentions due to its ultrahigh theoretical capacity and the most negative electrode potential. However, dendrite growth severely impedes the practical applications of the Li metal anode in rechargeable batteries. In this contribution, a mesoporous graphene with a high specific surface area was synthesized to host the Li metal anode. The mesoporous graphene host(MGH) has a high specific surface area(2090 m^2/g), which affords free space and an interconnected conductive pathway for Li plating and stripping, thus alleviating the volume variation and reducing the generation of dead Li during repeated cycles. More importantly, the high specific surface area of MGH efficiently reduces the local current density of the electrode, which favors a uniform Li nucleation and plating behavior, rendering a dendritefree deposition morphology at a low overpotential. These factors synergistically boost the Li utilization(90.1% vs. 70.1% for Cu foil) and life span(150 cycles vs. 100 cycles for Cu foil) with a low polarization of MGH electrode at an ultrahigh current of 15.0 mA/cm^2. The as-prepared MGH can provide fresh insights into the electrode design of the Li metal anode operating at high rates.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51,671,202 and 51,301,184)the Defense Industrial Technology Development Program(Grant No. JCKY2016404C001)sponsored by the "Liaoning BaiQianWan Talents" Program
文摘A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. Thermal cycling behavior of NiCoCrAlY-4 YSZ thermal barrier coatings(TBCs) with and without Pt modification was evaluated in ambient air at 1100?C up to 1000 cycles, aiming to investigate the effect of Pt on formation of thermally grown oxide(TGO) and oxidation resistance. Results indicated that a dual layered TGO, which consisted of top(Ni,Co)(Cr,Al)_2O_4 spinel and underlying α-Al_2O_3, was formed at the NiCoCrAlY/4 YSZ interface with thickness of 8.4μm, accompanying with visible cracks at the interface. In contrast, a single-layer and adherent α-Al_2O_3 scale with thickness of 5.6μm was formed at the interface of Pt-modified NiCoCrAlY and 4 YSZ top coating. The modification of Pt on NiCoCrAlY favored the exclusive formation of α-Al_2O_3 and the reduction of TGO growth rate, and thus could effectively improve overall oxidation performance and extend service life of TBCs. Oxidation and degradation mechanisms of the TBCs with/without Pt-modification were discussed.
