THERMODYNAMIC FORMALISM FOR SUBADDITIVE SEQUENCE OF DISCONTINUOUS FUNCTIONS

The topological pressure for subadditive sequence of discontinuous functions is defined on any invariant subset having a nested family of subsets in the compact metric space. Two subadditive variational principles associated with two different relatively weak conditions are developed for the defined topological pressure. As an application, we give an example on systems with nonzero Lyapunov exponents.

TEMPERATURE EFFECT ON LOW-CYCLE FATIGUE BEHAVIOR OF NICKEL-BASED SINGLE CRYSTALLINE SUPERALLOY

基于镍的单个水晶 superalloy 与的低周期的疲劳(LCF ) 行为[001 ] 取向在 T0 掳 C 的中间的温度和 T0 + 的更高的温度被学习在 10 的经常的低紧张率下面的 250 掳 C ? 3 s ? 1 在周围的空气。superalloy 展出了依赖于温度并且使用紧张振幅的周期的紧张压缩不对称现象。破裂表面上的分析证明表面和表面下的扔 micropores 是主要裂缝开始地点。内部 Ta 富有的碳化物经常在所有标本被观察。骨折的二种不同类型被 frac-togaphy 建议。一种类型被模式描绘 -- 我与一台用显微镜裂开在 T0 + 的不平的表面 250 掳 C。而在更低的温度 T0C 的另外的类型赞成了中的一个或几八面 { 111 } 飞机，与正常模式相对照 -- 我生长模式典型地在低装载观察了频率(几 Hz ) 。为二个裂开的模式的失败机制纬鈥 ? 正在砍在 T0 + 在矩阵和纬 / 纬鈥 ? 接口在 T0 掳 C 和裂开的反对 ned 和矩阵猛抛 250 掳 C。

Citron C-05 inhibits both the penetration and colonization of Xanthomonas citri subsp.citri to achieve resistance to citrus canker disease

Citrus canker,caused by Xanthomonas citri subsp.citri(Xcc),is a serious bacterial disease that affects citrus production worldwide.Citron C-05(Citrus medica)is the only germplasm in the Citrus genus that has been identified to exhibit strong resistance to Xcc.However,it has not been determined when,where,and how Xcc is restricted in the tissues of Citron C-05 during the infection process.In the present study,we investigated the spatiotemporal growth dynamics of an eGFP-labeled virulent Xcc(eGFP-Xcc)strain in Citron C-05 along with five susceptible biotypes(i.e.,lemon,pummelo,sour orange,sweet orange,and ponkan mandarin)upon inoculation via the spraying or leaf infiltration of a bacterial suspension.The results from extensive confocal laser scanning microscopy analyses showed that while Xcc grew rapidly in plants of all five susceptible genotypes,Xcc was severely restricted in the epidermal and mesophyll cell layers of the leaves of Citron C-05 in the early stage of infection.Not surprisingly,resistance against Xcc in Citron C-05 was found to be associated with the production of reactive oxygen species and hypersensitive response-like cell death,as well as greater upregulation of several defense-related genes,including a pathogenesis-related gene(PR1)and a glutathione S-transferase gene(GST1),compared with sweet orange as a susceptible control.Taken together,our results not only provide further valuable details of the spatiotemporal dynamics of the host entry,propagation,and spread of Xcc in both resistant and susceptible citrus plants but also suggest that resistance to Xcc in Citron C-05 may be attributed to the activation of multiple defense mechanisms.

Microstructure evolution of T91 steel after heavy ion irradiation at 550℃

Fe-Cr ferritic/martensitic(F/M)steels have been proposed as one of the candidate materials for the Generation IV nuclear technologies.In this study,a widely-used ferritic/martensitic steel,T91 steel,was irradiated by 196-MeV Kr^(+)ions at 550℃.To reveal the irradiation mechanism,the microstructure evolution of irradiated T91 steel was studied in details by transmission electron microscope(TEM).With increasing dose,the defects gradually changed from black dots to dislocation loops,and further to form dislocation walls near grain boundaries due to the production of a large number of dislocations.When many dislocation loops of primary a0/2<111>type with high migration interacted with other defects or carbon atoms,it led to the production of dislocation segments and other dislocation loops of a0<100>type.Lots of defects accumulated near grain boundaries in the irradiated area,especially in the high-dose area.The grain boundaries of martensite laths acted as important sinks of irradiation defects in T91.Elevated temperature facilitated the migration of defects,leading to the accumulation of defects near the grain boundaries of martensite laths.

Novel hard materials with controlled (W_(0.5)Al_(0.5))C grain shapes: in-situ high pressure preparation and mechanical properties

A novel hard material with various (W0.5Al0.5)C grain shapes was successfully prepared through mechanical alloying and in-situ high-pressure sintering process. X-ray diffraction apparatus and scanning electron microscopy were used to characterize the phase and the microstructures of the samples. The novel hard materials with "fibrous", "rounded" and "plate-like" grains, which do not contain sharp edges, have the improved mechanical properties. The bulk boundless (W0.5Al0.5)C hard material with various (W0.5Al0.5)C grain shapes possesses good mechanical properties and light weight. The formation mechanism for the non-equilibrium (W0.5Al0.5)C grains during in-situ high-pressure sintering is also discussed.

Review of Hydrogen Embrittlement in Metals: Hydrogen Diffusion, Hydrogen Characterization, Hydrogen Embrittlement Mechanism and Prevention

Hydrogen dissolved in metals as a result of internal and external hydrogen can affect the mechanical properties of the metals, principally through the interactions between hydrogen and material defects. Multiple phenomena such as hydrogen dissolution, hydrogen diffusion, hydrogen redistribution and hydrogen interactions with vacancies, dislocations, grain boundaries and other phase interfaces are involved in this process. Consequently, several hydrogen embrittlement(HE) mechanisms have been successively proposed to explain the HE phenomena, with the hydrogen-enhanced decohesion mechanism, hydrogenenhanced localized plasticity mechanism and hydrogen-enhanced strain-induced vacancies being some of the most important. Additionally, to reduce the risk of HE for engineering structural materials in service, surface treatments and microstructural optimization of the alloys have been suggested. In this review, we report on the progress of the studies on HE in metals, with a particular focus on steels. It focuses on four aspects:(1) hydrogen diffusion behavior;(2) hydrogen characterization methods;(3) HE mechanisms;and(4) the prevention of HE. The strengths and weaknesses of the current HE mechanisms and HE prevention methods are discussed, and specific research directions for further investigation of fundamental HE mechanisms and methods for preventing HE failure are identified.

Ground movements due to deep excavations in Shanghai： Design charts

当挖掘在软地面被做时，最近的研究澄清了表明自己的地面变丑机制的顺序。而且，在工作压力范围描述泥土的 deformability 的一个新框架用以前出版的土壤测试的一个大数据库被设计了。这篇论文试图利用这些进展，由分析与在上海的 braced 挖掘联系的地面运动的一个扩展数据库。它被看图表没能拿土壤 deformability 或相关变丑机制的特征的说明任何一个的那个常规图案，因此介绍重要散布。提供在与软地面的深度的关系澄清挖掘的土壤 deformability，墙僵硬，和几何学的影响的一套设计图表的表示的新方法被发现的 A。

In-situ observation and finite element analysis of fretting fatigue crack propagation behavior in 1045 steel

In this paper fretting fatigue crack behavior in 1045 steel is studied by in-situ observation and finite element analysis.in-situ fretting fatigue experiments are conducted to capture real-time fretting fatigue crack formation and propagation process.The fretting fatigue tests under different load conditions are carried out,then the lifetime and fracture surface are obtained.The crack propagation rates under different loading conditions are measured by in-situ observations.With in-situ observation,crack initiation location and direction are analyzed.Finite element model is used to calculate J-integral which then is applied to fitting with experimental crack growth rate,and establishing crack growth rate model.From fitted S-N curve,it turns out that smaller load ratio leads to higher lifetime.Crack initiates slightly below the point equivalent to line contact of the contact surface in different test conditions,and crack direction shows no obvious relationship with load parameters.The established crack growth rate model well agrees with the test results.

Simultaneous enhancement of strength and ductility in friction stir processed 2205 duplex stainless steel with a bimodal structure:experiments and crystal plasticity modeling

Achieving excellent strength-ductility synergy is a long-lasting research theme for structural materials.However,attempts to enhance strength usually induce a loss of ductility,i.e.,the strength-ductility trade-off.In the present study,the strength-ductility trade-off in duplex stainless steel(DSS)was overcome by developing a bimodal structure using friction stir processing(FSP).The ultimate tensile strength and elongation were improved by 140%and 109%,respectively,compared with those of the asreceived materials.Plastic deformation and concurrent dynamic recrystallization(DRX)during FSP were responsible for the formation of bimodal structure.Incompatible deformation resulted in the accumulation of dislocations at the phase boundaries,which triggered interpenetrating nucleation between the austenite and ferrite phases during DRX,leading to a bimodal structure.The in situ mechanical responses of the bimodal structure during tensile deformation were investigated by crystal plasticity finite element modeling(CPFEM).The stress field distribution obtained from CPFEM revealed that the simultaneous enhancement of strength and ductility in a bimodal structure could be attributed to the formation of a unique dispersion-strengthened system with the austenite and ferrite phases.It is indicated that the present design of alternating fine austenite and coarse ferrite layers is a promising strategy for optimizing the mechanical properties of DSSs.