Probabilistic analysis of tunnel face seismic stability in layered rock masses using Polynomial Chaos Kriging metamodel

Face stability is an essential issue in tunnel design and construction.Layered rock masses are typical and ubiquitous;uncertainties in rock properties always exist.In view of this,a comprehensive method,which combines the Upper bound Limit analysis of Tunnel face stability,the Polynomial Chaos Kriging,the Monte-Carlo Simulation and Analysis of Covariance method(ULT-PCK-MA),is proposed to investigate the seismic stability of tunnel faces.A two-dimensional analytical model of ULT is developed to evaluate the virtual support force based on the upper bound limit analysis.An efficient probabilistic analysis method PCK-MA based on the adaptive Polynomial Chaos Kriging metamodel is then implemented to investigate the parameter uncertainty effects.Ten input parameters,including geological strength indices,uniaxial compressive strengths and constants for three rock formations,and the horizontal seismic coefficients,are treated as random variables.The effects of these parameter uncertainties on the failure probability and sensitivity indices are discussed.In addition,the effects of weak layer position,the middle layer thickness and quality,the tunnel diameter,the parameters correlation,and the seismic loadings are investigated,respectively.The results show that the layer distributions significantly influence the tunnel face probabilistic stability,particularly when the weak rock is present in the bottom layer.The efficiency of the proposed ULT-PCK-MA is validated,which is expected to facilitate the engineering design and construction.

认知促进治疗在城市养老机构轻、中度老年期痴呆患者中的测试

目的:对城市养老机构内开展轻、中度老年期痴呆患者认知促进治疗的可行性进行测试。方法:选取天津市某养老院内轻、中度老年期痴呆患者55名,给予7周认知促进治疗,每周2次,共计14次。在干预前和7周末以10/66痴呆诊断工具包中的社区痴呆筛查表(CSID)、简易状态检查量表(MMSE)、阿尔茨海默病认知功能评价量表(ADAS-Cog)和痴呆患者生活质量量表(DEMQOL)对患者的功能和生活质量进行评估。结果:55名老年期痴呆患者经过7周治疗后,CSID和MMSE得分升高,ADAS-Cog得分下降,差异有统计学意义(P<0.05)。结论:认知促进治疗可以在城市养老机构中推广。

Deterministic and probabilistic analysis of great-depth braced excavations:A 32 m excavation case study in Paris

The Fort d’Issy-Vanves-Clamart(FIVC)braced excavation in France is analyzed to provide insights into the geotechnical serviceability assessment of excavations at great depth within deterministic and probabilistic frameworks.The FIVC excavation is excavated at 32 m below the ground surface in Parisian sedimentary basin and a plane-strain finite element analysis is implemented to examine the wall deflections and ground surface settlements.A stochastic finite element method based on the polynomial chaos Kriging metamodel(MSFEM)is then proposed for the probabilistic analyses.Comparisons with field measurements and former studies are carried out.Several academic cases are then conducted to investigate the great-depth excavation stability regarding the maximum horizontal wall deflection and maximum ground surface settlement.The results indicate that the proposed MSFEM is effective for probabilistic analyses and can provide useful insights for the excavation design and construction.A sensitivity analysis for seven considered random parameters is then implemented.The soil friction angle at the excavation bottom layer is the most significant one for design.The soil-wall interaction effects on the excavation stability are also given.

全景视角下智能教育软件的优选与推荐——《2023人工智能促进教育发展报告》节选八

智能教育软件,在智能技术与教育的融合应用中已发展出多样的形态和丰富的功能,在教育全场景中发挥着显著作用,不断影响教与学的效果并促进教育教学方式的变革。从“智能教育软件评估指标体系”看,智能教育软件的发展整体上处于功能全渗透、功用全覆盖、形态多样化的状态。其应用不仅能满足教学中展现、辅助、测评、推荐等多种需要,而且能在融合创新应用中发挥系统性延伸效能,促进教育方式的变革。而智能性的嵌入将为其未来的系统性集成需求提供条件。从学、教、管、评的全景着眼,通过十个特色用途介绍若干智能软件。在面向教师“教”场景下,现有的智能软件较为注重教师教研与授课辅助功能的开发,因此选取教师教研、教师授课两大用途,主要介绍三人行老师等三款教研软件,与畅言智慧课堂白板阅卷等三款授课软件。在面向学生“学”场景下,从自主学习、运动健康、社会实践三大用途展开,其中自主学习由于范围较广,将其分为艺术教育、学科学习、英语学习分支,主要介绍洋葱学院等软件。面向教育评测与管理的场景,智能软件多聚焦于班级管理、学校管理、考试测评,主要介绍智学网等软件。最后在综合性智能教育软件的推荐中,主要选取维词教师版等三款软件进行综合性评价与推荐,以期为中小学智能教育软件实践提供参考。

A Study on the Educational Mode and Optimization Strategies of“Micro Ideological and Political Education”

The model of“micro ideological and political education”is adapted to the characteristics of the new era and the real needs of ideological and political education in colleges and universities.Based on the work of“micro ideological and political education”in colleges and universities under the development of all-media integration,this study summarizes the main practices,achievements,and problems of“micro ideological and political education”in colleges and universities,and proposes to optimize and improve the work of“micro ideological and political education”from the perspectives of platform construction,work creation,team building,and guarantee mechanism.Optimization and enhancement are needed to effectively improve the relevance and effectiveness of“micro ideological and political education”work.

Rapid Detection of Accelerants in Fire Debris Using a Field Portable Mid-Infrared Quantum Cascade Laser Based Analyzer

Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.

Stability of Perfectly Matched Layers for Time Fractional Schrödinger Equation

It is an important issue to numerically solve the time fractional Schrödinger equation on unbounded domains, which models the dynamics of optical solitons propagating via optical fibers. The perfectly matched layer approach is applied to truncate the unbounded physical domain, and obtain an initial boundary value problem on a bounded computational domain, which can be efficiently solved by the finite difference method. The stability of the reduced initial boundary value problem is rigorously analyzed. Some numerical results are presented to illustrate the accuracy and feasibility of the perfectly matched layer approach. According to these examples, the absorption parameters and the width of the absorption layer will affect the absorption effect. The larger the absorption width, the better the absorption effect. There is an optimal absorption parameter, the absorption effect is the best.

工艺条件对聚丙烯/乙烯-醋酸乙烯酯共聚物原位微纤复合材料的微纤形态及流变性能影响

通过微纳层叠共挤技术实现聚丙烯(iPP)在乙烯-醋酸乙烯酯共聚物(EVA)中的原位成纤,研究不同牵引速率、螺杆转速对iPP/EVA(15/85)原位微纤复合材料(MFCs)中微纤形态及流变性能影响。扫描电子显微镜结果显示,在不同的牵引速率下,iPP均在EVA中形成微纤,随着牵引速率的增大,iPP微纤的直径先下降后增大。在不同螺杆转速下,iPP均形成长径比较大的微纤,随着螺杆转速的增加,形成的iPP微纤平均直径先增大后减小,微纤直径分布范围逐渐变窄。流变分析测试表明,当牵引速率为50r/min时,MFCs的G′、G″和η^*均最大;当螺杆转速为250r/min时,MFCs的G′、G″和η^*均最低。

天然嵌合基因的结构特性及其对基因设计的启示

天然嵌合基因(natural chimeric gene)是由两个或两个以上的独立基因天然融合而成的新基因,该类型基因的发现,突破了"一个基因对应一个染色体座位"的经典认知,扩展了基因的概念。在人类癌症研究过程中,诸多的嵌合基因可导致肿瘤相关疾病,并作为癌症分子的诊断标志而受到人们的广泛关注。本文基于嵌合基因生物信息学方面的相关研究,以癌基因为切入点,从天然嵌合基因的融合特点、转录、调控,以及融合蛋白的结构域组合形式和功能等方面,结合本研究组前期的相关工作,综述了嵌合基因融合结构和功能的研究进展,探讨了当前研究工作的困难与挑战,并对嵌合规律在新基因设计的应用作了展望。

气相二氧化硅物理吸附水测定及与表面硅羟基含量之间关系

热重分析法测定气相二氧化硅表面硅羟基含量操作简便、无化学试剂、误差小,近年来越来越受到关注。但是,其中物理吸附水脱除的条件还存在争议。文中选用国内外2家代表性公司生产的相同比表面积的气相二氧化硅为对象,详细地研究了升温模式、升温速率、等温温度和等温时间对其表面物理吸附水脱除的影响。确定了物理吸附水脱除的最优测试条件:10℃/min升温至200℃等温5 min。对比发现,相同条件下,国外产品的脱水量高于国内产品,这可能是由于国外产品具有更高的硅羟基含量所致。本工作不但找到了国内外产品关键性能的差距,而且完善了热重分析法测定气相二氧化硅表面羟基含量,并为相关测试标准的发展提供技术支撑。

罗丹明6G酰肼水杨醛席夫碱锌离子配合物的合成及光致变色性能表征综合实验

设计了一个6学时的综合化学实验,结合光致变色这一化学研究热点,向学生传授有机合成、波谱分析等相关知识。在本实验中,学生通过两步反应合成罗丹明6G酰肼水杨醛席夫碱分子,进而与锌离子结合,得到具有可逆光致变色性能的罗丹明6G酰肼水杨醛席夫碱锌离子配合物。学生通过观察溶液和固体基质中该配合物在光照前后的颜色和紫外光谱变化,了解光致变色现象。结合课堂讲解、文献阅读,了解光致变色现象产生的机理。本实验所需的试剂仪器简单、成本低廉,适于在化学或相关专业的本科实验教学中推广。此外,本实验现象明显,具有较强的趣味性,通过本实验不但可以提高学生的知识水平和专业素养,也可以培养其对化学的兴趣和热爱。

Automatic analytical approach for the determination of 12 illicit drugs and nicotine metabolites in wastewater using on-line SPE-UHPLC-MS/MS

In this study,we developed a novel on-line solid phase extraction(SPE)-ultra-high-performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS)-based analytical method for simultaneously quantifying 12 illicit drugs and metabolites(methamphetamine,amphetamine,morphine,codeine,6-monoacetylmorphine,benzoylecgonine,3,4-methylenedioxymethamphetamine,3,4-methylenedioxyamphetamine,cocaine,ketamine,norketamine,and methcathinone)and cotinine(COT)in wastewater samples.The analysis was performed by loading 2 m L of the sample onto an Oasis hydrophilic-lipophilic balance cartridge and using a cleanup step(5%methanol)to eliminate interference with a total run time of 13 min.The isotope-labeled internal standard method was used to quantify the target substances and correct for unavoidable losses and matrix effects during the on-line SPE process.Typical analytical characteristics used for method validation were sensitivity,linearity,precision,repeatability,recovery,and matrix effects.The limit of detection(LOD)and limit of quantification(LOQ)of each target were set at 0.20 ng/L and 0.50 ng/L,respectively.The linearity was between 0.5 ng/L and250 ng/L,except for that of COT.The intra-and inter-day precisions were<10.45%and 25.64%,respectively,and the relative recovery ranged from 83.74%to 162.26%.The method was used to analyze various wastewater samples from 33 cities in China,and the results were compared with the experimental results of identical samples analyzed using off-line SPE.The difference rate was between 19.91%and-20.44%,and the error range could be considered acceptable.These findings showed that on-line SPE is a suitable alternative to off-line SPE for the analysis of illicit drugs in samples.

Experimental study on evolution law for particle breakage during coal and gas outburst

Coal and gas outburst is a dynamic phenomenon in underground mining engineering that is often accompanied by the throwing and breakage of large amounts of coal.To study the crushing effect and its evolution during outbursts,coal samples with different initial particle sizes were evaluated using a coal and gas outburst testing device.Three basic particle sizes,5–10 mesh,10–40 mesh,and 40–80 mesh,as well as some mixed particle size coal samples were used in tests.The coal particles were pre-compacted at a pressure of 4 MPa before the tests.The vertical ground stress(4 MPa)and the horizontal ground stress(2.4 MPa)were initially simulated by the hydraulic system and maintained throughout.During the tests,the samples were first placed in a vacuum for 3 h,and the coal was filled with gas(CH4)for an adsorption time of approximately 5 h.Finally,the gas valve was shut off and the coal and gas outburst was induced by quickly opening the outburst hole.The coal particles that were thrown out by the outburst test device were collected and screened based on the particle size.The results show the following.(1)Smaller particle sizes have a worse crushing effect than larger sizes.Furthermore,the well-graded coal particles are weakly broken during the outburst process.(2)As the number of repeated tests increases,the relative breakage index grows;however,the increment of growth decreases after each test,showing that further fragmentation becomes increasingly difficult.

Estimating the macrobenthic species richness with an optimized sampling design in the intertidal zone of Changjiang Estuary

It is a challenge in the field sampling to face conflict between the statistical requirements and the logistical constraints when explicitly estimating the macrobenthos species richness in the heterogeneous intertidal wetlands. To solve this problem, this study tried to design an optimal, efficient and practical sampling strategy by comprehensively focusing on the three main parts of the entire process(to optimize the sampling method, to determine the minimum sampling effort and to explore the proper sampling interval) in a typical intertidal wetland of the Changjiang(Yangtze) Estuary, China. Transect sampling was selected and optimized by stratification based on pronounced habitat types(tidal flat, tidal creek, salt marsh vegetation). This type of sampling is also termed within-transect stratification sampling. The optimal sampling intervals and the minimum sample effort were determined by two beneficial numerical methods: Monte Carlo simulations and accumulative species curves. The results show that the within-transect stratification sampling with typical habitat types was effective for encompassing 81% of the species, suggesting that this type of sampling design can largely reduce the sampling effort and labor. The optimal sampling intervals and minimum sampling efforts for three habitats were determined: sampling effort must exceed 1.8 m^2 by 10 m intervals in the salt marsh vegetation, 2 m^2 by 10 m intervals in the tidal flat, and 3 m^2 by 1 m intervals in the tidal creek habitat. It was suggested that the differences were influenced by the mobility range of the dominant species and the habitats' physical differences(e.g., tidal water, substrate, vegetation cover). The optimized sampling strategy could provide good precision in the richness estimation of macrobenthos and balance the sampling effort. Moreover, the conclusions presented here provide a reference for recommendations to consider before macrobenthic surveys take place in estuarine wetlands. The sampling strategy, focusing on the three key parts of the sampling design, had a good operational effect and could be used as a guide for field sampling for habitat management or ecosystem assessment.

Review on mechanisms and structure-activity relationship of hypoglycemic effects of polysaccharides from natural resources

Diabetes mellitus(DM)is a common multifactorial disease,causing various complications,such as chronic metabolism.The current therapies for diabetes mellitus are commercial diabetic drugs that have different definite side effect.However,polysaccharides mainly extracted from natural resources,have advantages of safety,accessibility,and anti-diabetic potential.We have summarized recent research of natural polysaccharides with hypoglycemic activities,focusing on different pharmacological mechanisms in various cell and animal models.The relationships of structure-hypoglycemic effect are also discussed in detail.This review could provide a comprehensive perspective for better understanding on development and mechanism of natural polysaccharides against diabetes mellitus,which have been required by clinical studies yet.

弥漫性大B细胞淋巴瘤的治疗选择

弥漫性大B细胞淋巴瘤(diffuse large B-cell lymphpma,DLBCL)是非霍奇金淋巴瘤中最常见的类型,在分子遗传学、免疫表型等方面具有高度异质性,患者临床预后也截然不同。R-CHOP方案为DLBCL标准治疗方案,如何进一步提高DLBCL疗效是近年来的研究热点。2015年美国临床肿瘤学会(ASCO)提出基于细胞起源分型进行R-CHOP+X方案治疗的策略,但这些方案相继失败。基于更加精准的分层方法,筛选出不同DLBCL亚组并进行针对性治疗,是未来DLBCL治疗的方向。此外,抗体-药物偶联物、双特异性抗体和嵌合抗原受体T细胞(chimeric antigen receptor T-cell,CAR-T)等免疫治疗近年来取得突破性进展,为DLBCL患者带来新的希望。本文针对基于精准分层的DLBCL靶向治疗、免疫治疗的最新进展及遗传学检测方法予以综述。

Characterization of oil component and solid particle of oily sludge treated by surfactant-assisted ultrasonication

The ultrasonic technique has been demonstrated to be a promising method for the disposal of hazardous oily sludge.However,the separation of oil from the surfaces of the solid particles is still difficult due to the strong interaction between the oil and solid particle.In this study,three types of surfactants were used to assist the ultrasonic treatment of oily sludge.The oil component,surface composition,and structure of the solid particle were determined.The results showed that different surfactants had different oil removal abilities.In the three surfactant-assisted sonication systems,the oil removal rate increased during the starting reaction period and then decreased with longer sonication time.The results of four components analysis suggested that surfactant easy to be ionized in water posed a better removal effect on resins,while the amphiphilic surfactant preferred saturates,aromatics and asphaltenes.The morphology analysis indicated that particle size was shattered into smaller ones by the ultrasonic process,and the wettability of the solid surface also changed during this treatment.The characterization of the oil component and solid particle during surfactant-assisted ultrasonication treatment will help to better understand the separation of oil from oily sludge and improve the oil recovery efficiency from oily sludge.

Interfacial Morphology and Bonding Mechanism of Explosive Weld Joints

Interfacial structure greatly affects the mechanical properties of laminated plates.However,the critical material properties that impact the interfacial morphology,appearance,and associated bonding mechanism of explosive welded plates are still unknown.In this paper,the same base plate(AZ31B alloy)and different flyer metals(aluminum alloy,copper,and stainless steel)were used to investigate interfacial morphology and structure.SEM and TEM results showed that typical sine wave,wave-like,and half-wave-like interfaces were found at the bonding interfaces of Al/Mg,Cu/Mg and SS/Mg clad plates,respectively.The different interfacial morphologies were mainly due to the differences in hardness and yield strength between the flyer and base metals.The results of the microstructural distribution at the bonding interface indicated metallurgical bonding,instead of the commonly believed solid-state bonding,in the explosive welded clad plate.In addition,the shear strength of the bonding interface of the explosive welded Al/Mg,Cu/Mg and SS/Mg clad plates can reach up to 201.2 MPa,147.8 MPa,and 128.4 MPa,respectively.The proposed research provides the design basis for laminated composite metal plates fabrication by explosive welding technology.

Reducing defect of inorganic perovskite film by sulphur-containing Lewis base for robust photodetectors

Sluggish charge transfer in perovskite film induced by inherent defects such as uncoordinated Pb2+undoubtedly hinders the rapid response of self-powered photovoltaic-typed detector.Based on interaction between Lewis acids and bases,herein,we employ thiourea molecule as a multifunctional Lewis base to significantly improve the quality of all-inorganic CsPbIBr2 perovskite film.After careful characterizations,the quality of perovskite film has been well regulated.Arising from the reduced defect and the reinforced the interfacial charge extraction owing to the strong interaction between uncoordinated Pb2+ions and the-C=S groups in thiourea and the formation of hydrogen bond at perovskite/TiO_(2) interface,an enhanced responsivity of 0.335 A W-1 and specific detectivity of 3.92×10^(12) Jones has been achieved for the self-powered,carbon-electrode based photodetector,which is comparable to the state-of-theart device based on CsPbIBr2 film.More importantly,the device free of encapsulation remains 82.8%of initial performance after storage over 56 days in ambient atmosphere,promoting the practical deployment of perovskite products.

Application of hydrophobic ionic liquid [Bmmim][PF6] in solvent extraction for oily sludge

In this study, an ionic liquid(IL), 1-butyl-2,3-dimmmethylimidazolium hexafluorophosphate([Bmmim][PF6]),was used in combination with a composite solvent of methyl acetate and n-heptane to enhance the oil extraction from oily sludge. The oil recovery increased by approximately 15% compared with that of solvent extraction without [Bmmim][PF6] at the optimal ratios of IL to sludge and solvents to sludge, which were at 2:5(M/M) and 4:1(V/M), respectively. The saturate, aromatic, resin and asphaltene(SARA) analysis revealed that the recovery of resins and asphaltenes was increased by 14% and 38%, respectively, in the solvent extraction with the addition of [Bmmim][PF6]. [Bmmim][PF6] maintained a good performance after its reuse four times. The addition of[Bmmim][PF6] changed the adhesion forces between oil and soil. The IL-assisted solvent extraction procedure followed the pseudo second-order kinetic model, while the unassisted solvent extraction procedure followed the pseudo first-order kinetic model. The results also demonstrated that [Bmmim][PF6] decreased the solvent consumption by approximately 60% each time. Additionally, [Bmmim][PF6] can be easily separated. The results suggested that enhancing the solvent extraction with this IL is a promising way to recover oil from oily sludge with a higher oil recovery rate and lower organic solvent consumption than those with the unassisted solvent extraction method.