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Unified description of sand behavior

Feng ZHANG, Bin YE, Guanlin YE

《结构与土木工程前沿（英文）》 2011年第5卷第2期页码 121-150 doi: 10.1007/s11709-011-0104-z

摘要： In this paper, the mechanical behavior of sand, was systematically described and modeled with a elastoplastic model proposed by Zhang et al. [ ]. Without losing the generality of the sand, a specific sand called as Toyoura sand, a typical clean sand found in Japan, has been discussed in detail. In the model, the results of conventional triaxial tests of the sand under different loading and drainage conditions were simulated with a fixed set of material parameters. The model only employs eight parameters among which five parameters are the same as those used in Cam-clay model. Once the parameters are determined with the conventional drained triaxial compression tests and undrained triaxial cyclic loading tests, then they are fixed to uniquely describe the overall mechanical behaviors of the Toyoura sand, without changing the values of the eight parameters irrespective of what kind of the loadings or the drainage conditions may be. The capability of the model is discussed in a theoretical way.

关键词： constitutive model sand stress-induced anisotropy density structure

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Aspects of rock permeability

Lianyang ZHANG

《结构与土木工程前沿（英文）》 2013年第7卷第2期页码 102-116 doi: 10.1007/s11709-013-0201-2

摘要： Effective evaluation of rock permeability is required in different energy, engineering and environmental projects. Although much research has been conducted on rock permeability, it is still one of the most difficult tasks for practicing rock engineers to accurately determine rock permeability. Based on a comprehensive literature review, this paper outlines the key aspects of rock permeability by presenting the representative values of the permeability of different rocks, describing the empirical and semi-empirical correlations for estimating the permeability of rocks, and discussing the main factors affecting the permeability of rocks. The factors discussed include stress, depth, temperature, and discontinuity intensity and aperture. This paper also highlights the scale effect on rock permeability, interconnectivity of discontinuities, and anisotropy of rock permeability. This paper provides the fundamental and essential information required for effective evaluation of rock permeability.

关键词： rock permeability discontinuity stress temperature scale effect anisotropy

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Analysis on annealing-induced stress of blind-via TSV using FEM

Jie SHAO, Tielin SHI, Li DU, Lei SU, Xiangning LU, Guanglan LIAO

《机械工程前沿（英文）》 2018年第13卷第3期页码 401-410 doi: 10.1007/s11465-017-0457-7

摘要：

Copper-filled through silicon via (TSV) is a promising material owing to its application in high-density three-dimensional (3D) packaging. However, in TSV manufacturing, thermo-mechanical stress is induced during the annealing process, often causing reliability issues. In this paper, the finite element method is employed to investigate the impacts of via shape and SiO₂ liner uniformity on the thermo-mechanical properties of copper-filled blind-via TSV after annealing. Top interface stress analysis on the TSV structure shows that the curvature of via openings releases stress concentration that leads to ~60 MPa decrease of normal stresses, s_xx and s_yy, in copper and ~70 MPa decrease s_xx of in silicon. Meanwhile, the vertical interface analysis shows that annealing-induced stress at the SiO₂/Si interface depends heavily on SiO₂ uniformity. By increasing the thickness of SiO₂ linear, the stress at the vertical interface can be significantly reduced. Thus, process optimization to reduce the annealing-induced stress becomes feasible. The results of this study help us gain a better understanding of the thermo-mechanical behavior of the annealed TSV in 3D packaging.

关键词： through silicon via (TSV) annealing-induced stress interface stress plastic deformation finite element method

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Experimental study on compaction-induced anisotropic mechanical property of rockfill material

Xiangtao ZHANG, Yizhao GAO, Yuan WANG, Yu-zhen YU, Xun SUN

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 109-123 doi: 10.1007/s11709-021-0693-0

摘要： The anisotropy of rockfill materials has a significant influence on the performance of engineering structures. However, relevant research data are very limited, because of the difficulty with preparing specimens with different inclination angles using traditional methods. Furthermore, the anisotropy test of rockfill materials is complex and complicated, especially for triaxial tests, in which the major principal stress plane intersects with the compaction plane at different angles. In this study, the geometric characteristics of a typical particle fraction consisting of a specific rockfill material were statistically investigated, and the distribution characteristics of particle orientation in specimens prepared via different compaction methods were examined. For high-density rockfill materials, a set of specimen preparation devices for inclined compaction planes was developed, and a series of conventional triaxial compression tests with different principal stress direction angles were conducted. The results reveal that the principal stress direction angle has a significant effect on the modulus, shear strength, and dilatancy of the compacted rockfill materials. Analysis of the relationship between the principal stress direction angles, change in the stress state, and change in the corresponding dominant shear plane shows that the angle between the compacted surface and dominant shear plane is closely related to interlocking resistance associated with the particle orientation. In addition, different principal stress direction angles can change the extent of the particle interlocking effect, causing the specimen to exhibit different degrees of anisotropy.

关键词： rockfill inclination of specimen preparation anisotropy mechanical property mechanism

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The early signal substances induced by heat stress in brains of mice

WANG Chunxu, WANG Hanxing

《医学前沿（英文）》 2008年第2卷第4期页码 391-395 doi: 10.1007/s11684-008-0075-1

摘要： To study the effects of early signal substances induced by heat stress in brains of Kunming mice, six-month-old mice ( = 72) were pretreated with heat stress and subsequent ischemia/reperfusion by clipping of their bilateral cervical common arteries for 7 min. According to different treatments, animals were randomly divided into four groups: (1) normal control group; (2) heat stress pretreatment followed by ischemia and reperfusion group (HS/IR); (3) ischemia and reperfusion group (IR); (4) heat stress group (HS). Animals in the later three groups were subdivided into 3 subgroups (1 day, 4 days, 14 days), respectively. The changes in the expression of cAMP response element binding protein (CREB) and calcitonin gene-related peptide (CGRP) were detected by immunohistochemistry and computer image analysis methods. The results showed that compared with the normal group, the expressions of CREB in the hippocampal CA1 region increased significantly in the HS, HS/IR and IR groups ( < 0.05). Compared to the normal group, heat stress could result in CGRP excretion and redistribution in the cerebrum, with the highest level in the 4 d HS/IR group. Following heat stress, CGRP immunoreactivity was observed in varicose fibers and neuronal perikarya within the CA1 region. The results indicate that heat stress can induce CREB expression, which in turn stimulates CGRP secretion.

关键词： calcitonin gene-related subsequent ischemia/reperfusion computer cerebrum CGRP excretion

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煤矿开采动静载叠加诱发断层冲击地压机理 Article

蔡武, 窦林名, 司光耀, 胡亚伟

《工程（英文）》 2021年第7卷第5期页码 687-700 doi: 10.1016/j.eng.2020.03.017

摘要：

断层作为煤层采掘过程中普遍存在的一种地质构造，其独特不连续结构控制着煤岩的变形、破坏与力学性质，该结构与煤层采掘活动之间的相互作用是断层活化及其诱发冲击地压的关键。本文通过调研总结煤层采掘活动与断层赋存状态之间的概念模型，提出了采动应力主导和矿震动载主导两种断层活化类型的力学机制及其动静载叠加诱冲机理；其次，结合物理实验、数值模拟和现场微震监测结果验证了模型与机理的合理性；在此基础上，针对性地探讨了断层冲击地压监测与防治的方法和策略。研究结果表明，断层冲击地压是由断层煤柱高静载与断层活化动载叠加诱发，其中，断层煤柱高静载是断层与顶板结构双重作用导致，断层活化动载是由采动应力主导型局部解锁活化、等效劈裂破坏和矿震动载主导型超低摩擦效应组成。研究结果对于系统理解断层冲击地压机理、监测与防治具有重要指导意义。

关键词：冲击地压断层活化采动应力矿震动载应力断层煤柱

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树盘干缩异向性引起应变的测算及分析

付宗营,赵景尧,蔡英春

《中国工程科学》 2014年第16卷第4期页码 25-29

摘要：

研究探讨了干燥过程中树盘受抑制干缩应变、自由干缩应变、弹性应变、黏弹性蠕变应变以及机械吸附蠕变的图像解析测算法；运用该方法测算了白桦树盘常规缓慢干燥（含水率分布均匀）过程中干缩异向性引起的弦向各应变，分析了干燥过程中不同含水率阶段的应力状态及应力与各应变的关系。结果表明：应变的图像解析测算法可满足精度要求；树盘干燥至fiber saturation point( FSP)以下，弦向首先受拉伸应力作用，随着干燥的进行，拉伸应力转变为压缩应力；应力方向与各应变对应关系不同，与黏弹性蠕变应变无明显对应关系，与机械吸附蠕变基本对应。

关键词：图像解析法树盘干缩异向性干燥应力弦向应变

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Apigenin alleviates neomycin-induced oxidative damage via the Nrf2 signaling pathway in cochlear hair

《医学前沿（英文）》 2022年第16卷第4期页码 637-650 doi: 10.1007/s11684-021-0864-3

摘要： Oxidative stress plays an important role in the pathogenesis of aminoglycoside-induced hearing loss and represents a promising target for treatment. We tested the potential effect of apigenin, a natural flavonoid with anticancer, anti-inflammatory, and antioxidant activities, on neomycin-induced ototoxicity in cochlear hair cells in vitro. Results showed that apigenin significantly ameliorated the loss of hair cells and the accumulation of reactive oxygen species upon neomycin injury. Further evidence suggested that the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway was activated by apigenin treatment. Disruption of the Nrf2 axis abolished the effects of apigenin on the alleviation of oxidative stress and subsequent apoptosis of hair cells. This study provided evidence of the protective effect of apigenin on cochlear hair cells and its underlying mechanism.

关键词： apigenin aminoglycosides ototoxicity oxidative stress Nrf2 signaling pathway

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Stress induced polarization switching and coupled hysteretic dynamics in ferroelectric materials

Linxiang WANG, Roderick MELNIK, Fuzai LV

《机械工程前沿（英文）》 2011年第6卷第3期页码 287-291 doi: 10.1007/s11465-011-0230-2

摘要：

The dynamic responses of ferroelectric materials upon external mechanical and electrical stimulations are inherently nonlinear and coupled. In the current paper, a macroscopic differential model is constructed for the coupled hysteretic dynamics via modeling the orientation switching induced in the materials. A non-convex potential energy is constructed with both mechanic and electric field contributions. The governing equations are formulated as nonlinear ordinary differential equations by employing the Euler-Lagrange equation, and can be easily recast into a state space form. Hysteresis loops associated with stress induced polarization switching and butterfly-shaped behavior in ferroelectric materials are also successfully captured. The effects of mechanical loadings on the electrically induced switching are numerically investigated, as well as the mechanically-induced switching with various bias electric fields.

关键词： differential model state space electromechanical switching butterfly effects hysteresis

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TA2板料激光热应力弯曲成形及其力学性能研究

周益军,张永康,游文明

《中国工程科学》 2007年第9卷第10期页码 40-44

摘要：

用HVS-1000显微硬度测试仪、X-350A型X射线应力测定仪，以2.5 kW SM2000SM快轴流CO₂激光器对0.6 mm厚的TA2板料进行扫描，按照正交试验理论安排成形工艺参数，研究了TA2板料弯曲成形时主要工艺参数对弯曲角度的影响，以及试样表面残余应力的分布和试样断面上的显微硬度变化。结果表明：正交试验中的4个工艺参数的作用是不同的，按其变化对弯曲变形量影响的大小排序，依次是扫描次数、光斑直径、激光束功率、扫描速度；成形参数对试样表面的残余应力分布也存在一定的影响；试样变形区断面上的显微硬度变化呈现出一定的规律。

关键词：激光技术热应力板料弯曲成形残余应力显微硬度

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Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1480-1493 doi: 10.1007/s11709-021-0776-y

摘要： In waterfront geotechnical engineering, seismic and drainage conditions must be considered in the design of retaining structures. This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions. The method comprises the following steps: i) determination of the total head, ii) upper bound solution of seismic active earth thrust, and iii) deduction for the earth pressure distribution. The determination of total head h(x,z) relies on the Fourier series expansions, and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem. Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure. The numerical results confirm the validity of the total head distribution. Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure. The method can be applied to the seismic design of waterfront retaining walls.

关键词： seismic active earth pressure partial seepage flow pore pressure anisotropy upper bound theorem

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Phosphorene: Current status, challenges and opportunities

Anandarup Goswami, Manoj B. Gawande

《化学科学与工程前沿（英文）》 2019年第13卷第2期页码 296-309 doi: 10.1007/s11705-018-1783-y

摘要： The field of 2-dimensional (2D) materials has witnessed a sharp growth since its inception and can majorly be attributed to the substantial technical and scientific developments, leading to significant improvements in their syntheses, characterization and applications. In the list of 2D materials, the relatively newer addition is phosphorene, which ideally consists of a single layer of black phosphorous. Keeping in mind the past, and ongoing research activities, this short account offers a brief overview of the present status and the associated challenges in the field of phosphorene-related research, with special emphasis on their syntheses, properties, applications and future opportunities.

关键词： phosphorene black phosphorous anisotropy single layer thermoelectric chemical vapor deposition catalysis battery supercapacitor

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Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 110-122 doi: 10.1007/s11709-018-0476-4

摘要： Asphalt concrete (AC) overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing pavements. The strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement material. This study was conducted to analyze the influence of anisotropy, modulus gradient properties, and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays, as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA). The mechanical behaviors of the AC overlay were numerically obtained using the three-dimensional finite element method with the aid of ABAQUS a commercial program. Variations in the AC overlay’s modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients method. Comparing the mechanical behavior in terms of surface deflection, stress, and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC overlay. In addition, the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore, future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.

关键词： asphalt concrete overlay anisotropy temperature gradients modulus gradients finite element simulation sensitivity analysis

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Treatment of gingival hyperplasia induced by cyclosporine A

MA Jingzhi, LI Ming, CAO Yingguang

《医学前沿（英文）》 2008年第2卷第3期页码 290-294 doi: 10.1007/s11684-008-0055-5

摘要： The clinical therapy for cyclosporine A (CsA)-induced gingival hyperplasia (GH) and the pathological changes in hyperplastic gingival tissues were investigated. Nine cases of CsA-induced GH after renal transplantation were subjected to periodontal non-surgical treatment and surgical treatment and were followed up. Gingival index (GI), dental plaque index (PLI) and GH degree (GHD) at different time points were measured. Under light and electron microscopy, the pathological changes in hyperplastic gingival tissues were observed. The CsA concentrations in gingival tissues and blood were determined by using fluorescence polarization immunoassay with TDFL monoclonal antibody. The results showed that GI, PLI and GHD in patients with GH declined after periodontal treatment. Two patients suffered from different degrees of GH during the 6 months to 54 months post-transplantation. Under transmission electron microscopy, fibroblasts in the hyperplastic gingival tissues were enlarged, cytoplasmic rough endoplasmic reticula were abundant and expanded slightly, and a few fibroblasts with early apoptotic changes were seen. The concentrations of CsA in hyperplastic gingival tissues were from 351.00 to 1345.47 ng/mL, which were significantly higher than in the blood of the same patients taken at the same time points. It was concluded that GI and PLI declined after periodontal treatment in combination with surgical treatment in patients taking CsA for a long time, but in some patients, GH recurred. The fact that the concentration of CsA in hyperplastic gingival tissues is higher than in blood awaits further studies.

关键词： post-transplantation Gingival cytoplasmic CsA-induced further