High-entropy ferroelastic rare-earth tantalite ceramic: (Y0.2Ce0.2Sm0.2Gd0.2Dy0.2)TaO4

In this study, high-entropy rare-earth tantalate ceramics (Y_0.2Ce_0.2Sm_0.2Gd_0.2Dy_0.2)TaO₄ ((5RE_0.2)TaO₄) have been successfully fabricated. The possibility of formation of (5RE_0.2)TaO₄ was verified via first-principles calculations. In addition, the phase structure, ferroelastic toughening mechanism, thermophysical, and mechanical properties were systematically investigated. The (5RE_0.2)TaO₄ ceramics have lower phonon thermal conductivity (1.2–2.6 W·m^–1·K^–1) in the entire temperature range than that of RETaO₄ and YSZ. (5RE_0.2)TaO₄ has a higher fracture toughness and lower brittleness index than YSZ. The thermal expansion coefficients of (5RE_0.2)TaO₄ are as high as 10.3 × 10^-6 K^–1 at 1200°C and Young's modulus is 66–189 GPa, and thus, (5RE_0.2)TaO₄ possesses great potential for application in thermal barrier coatings (TBCs).     

Biomimetic Lamellar Chitosan Scaffold for Soft Gingival Tissue Regeneration

Mucogingival surgery has become a common procedure for soft gingival tissue reparation in dental clinical practice, which mainly relies on autograft or commercial collagen membranes (CM). However, the autograft faces grand challenges in source availability and long-term post-surgery pain management, and the CM is restricted by its poor mechanical properties in an aqueous environment. Here, it is reported that a bio-inspired lamellar chitosan scaffold (LCS) with long range ordered porous structure, manufactured through a bidirectional freezing method, can serve as a promising gingival tissue engineering material. The LCS not only exhibits excellent mechanical properties in the hydrated state but also accelerates vessel formation and soft tissue regeneration in vivo. Most interestingly, the LCS is found to be capable of inducing macrophage differentiation to M2 macrophages, which is thought to play an important role in tissue regeneration. These advantages combined with its easy and low-cost preparation process make the LCS a promising candidate for dental clinical applications.     

Phase-change regulation criterion based on size-dependent lattice distortion rate and born theory for VO2 nanomaterials

Vanadium dioxide (VO₂) is a promising thermally induced phase transition material because of the abrupt changes in electrical and optical properties. However, the high phase transition temperature of VO₂ and its unspecified modulation relationship need to be resolved urgently. Herein, we proposed a simple and precise regulation criterion for VO₂ materials based on size-dependent lattice distortion rate and Born theory. The results indicated that the application of a tensile stress changed the elastic properties of the VO₂, which promoted VO₂ phase transition, and regulated the phase transition temperature. Moreover, the specific modulation relationship between the stress and phase transition temperature of VO₂ was confirmed experimentally. These results show that our criterion provides theoretical guidance to regulate VO₂ thermally induced phase transition materials.     

Hierarchical composite of biomass derived magnetic carbon framework and phytic acid doped polyanilne with prominent electromagnetic wave absorption capacity

To solve the electromagnetic pollution,herein,a CoFe₂O₄/C/PANI composite was developed by a green route,which was constructed with spinel of metal oxide,graphitized carbon and conductive polymer composites.Benefiting from the designable interfaces and increased dipoles,the microwave dielectric response capability can be boosted significantly and resulted in the enhanced microwave absorbing performance.As revealed by the reflection loss curve,the minimum reflection loss(RLmin) reached-51.81 dB at 12.4 GHz under a matched thickness of 2.57 mm.At 2.5 mm,the effective absorbing band covered 8.88 GHz,suggesting the desirable wideband feature.In our case,the method of utilization of a novel green way to fabricate multiple-component EM absorber can be a promising candidate for high-performance EM absorber.     

Dielectric breakdown behavior of ferroelectric ceramics: The role of pores

Dielectric breakdown is a fundamental issue for ferroelectric ceramics. In this work, a phase-field method is introduced to study the breakdown behavior of ferroelectric ceramics with pores randomly distributed. Effects of the position and the size of pores on the breakdown behavior are analyzed. Results indicate that the position of pores, for example in grains or at grain boundaries, has a significant influence on the breakdown strength of ferroelectric ceramics. The nominal breakdown strength of ferroelectric ceramics with 2 % pores at grain boundaries is almost 50 % higher than 2 % pores in grains. Further, for ferroelectric ceramics with a certain porosity, the smaller the pore size, the higher the breakdown strength. As the nominal pore size decreases from 2.5 to 1, the nominal breakdown strength is enhanced from 0.73 to 1.16. Such results agree well with the widely accepted Gerson-Marshall model and previously published experimental observations.     

川东南丁山地区燕山期—喜马拉雅期差异构造-热演化与页岩气保存

中国的海相富有机质页岩经历了多期构造改造，其含气性具有明显的差异。页岩气在不同构造演化阶段的保存条件是揭示页岩气差异富集机理的关键科学问题之一，开展构造-热演化研究可以明确其热演化史和构造隆升-剥蚀过程，为其评价提供演化格架。研究以丁山地区下古生界页岩为对象，联合磷灰石裂变径迹、磷灰石（U-Th）/He和锆石（U-Th）/He等多个古温标反演热演化史，结合镜质体反射率重建的最高古地温剖面，对丁山地区燕山期以来的差异构造隆升过程和剥蚀量进行了恢复，并在此基础上结合流体包裹体分析对丁山地区龙马溪组页岩的压力演化过程进行了模拟；根据页岩在埋藏—抬升过程中的温、压演化特征，定量表征了不同抬升阶段页岩含气量的变化，建立了龙马溪组页岩"埋藏—生烃—抬升"的演化格架。分析表明，丁山地区在燕山期和喜马拉雅期经历了不同的构造隆升过程。燕山期表现为"早期快速隆升—晚期缓慢隆升"的分段隆升，具有自NW向SE递进隆升且隆升幅度逐渐增大的特征；喜马拉雅期表现为整体快速隆升。燕山期是丁山地区产生差异构造隆升的主要时期。受这种差异构造隆升-剥蚀作用的影响，龙马溪组页岩的降温、降压过程和页岩气的散失过程具有明显的差异。燕山期的差异构造隆升是造成丁山地区龙马溪组页岩含气性呈平面分带的主要原因。     

基于U-Net改进的太阳暗条自动检测

提出一种基于改进后的U-Net深度学习网络进行自动识别Hα全日面太阳图像中的太阳暗条方法.这种方法不仅可以准确识别暗条,而且可以最大限度地减少太阳图像噪声的影响.首先,建立一个原始暗条数据集,由深度学习所需的数万张图像组成;其次,使用改进后的U-Net深度卷积网络开发一种用于太阳暗条识别的自动化方法.为了验证该方法的性能,使用一个包含50对手动校正的Hα全日面图像的数据集进行测试,这些图像是从2013年大熊湖太阳天文台/全日面Hα望远镜(BBSO/FDHA)获得的.经过交叉验证,结果表明该技术可以有效地识别全日面Hα图像中的暗条.     

阶梯管件的矫直方法研究

针对单弧度弯曲阶梯管件,采用三点过弯压力矫直的修正方式,根据材料弹塑性力学理论,基于双线性强化弹塑性材料本构关系,解析了考虑变截面处应力集中因素的阶梯管件变形过程,推导了矫直行程计算公式.利用有限元软件显示动力学分析的阶梯管件矫直模拟过程以及相应的矫直实验对模型的正确性进行了验证,仿真和实验结果表明,矫直后的阶梯管件具有直线度高,矫直效果好的特点.     

复杂地质条件下浅埋暗挖隧道下穿河道设计案例与关键技术

北京某地下工程与地铁连接通道施工中,针对富水砂层复杂地质条件下浅埋暗挖隧道下穿河道危险性大、安全风险高等问题,采用围堰导流、超前深孔注浆、水平旋喷注浆及信息化设计施工等关键技术,创造了稳定可靠的干地施工条件,保证了河道安全和施工质量.     

水夹点技术在高校食堂洗菜工艺中的应用

以洗菜工艺为例,利用水夹点技术对某高校中某食堂清洁用水进行分析,实现了生活用水的节水减排目标,节约水量分别占洗菜工艺和全用水过程的65％和28％.