Synthesis and structural characterization of macroporous bioactive glass

Porous sol-gel glass of CaO-SiO2-P2O5 system with macropores larger than 100 μm was prepared by adding stearic acid as pore former when the sintering was carried out at 700 ℃ for 3h.The sol-gel porous glass shows an amorphous structure. The diameter of the pore created by pore former varies from 100 to 300 μm, and macroporous glass has a narrow and small pore size distribution in mesoporous scale. The porosity and pore size of macroporous bioactive glass can be controlled.

Evaluation Indicators and Extraction Method for Pitting Corrosion of Structural Steel

A set of evaluation indicators based on corrosion ratio in theory for assessing the extent of pitting corrosion and performance reduction are proposed. In order to quantify the morphology of pitting corrosion and extract the evaluation indicators,the 3D profile data obtained by pitting morphology measurement are imported into a special written program to automatically determine the location of each corrosion pit and distill any desired data pertinent to the pitting morphology. The results show that this method seems to be effective to analyze the corroded surface and characterize the pitting morphology.

Innovative Techniques Unveiled in Advanced Sheet Pile Curtain Design

This thorough review explores the complexities of geotechnical engineering, emphasizing soil-structure interaction (SSI). The investigation centers on sheet pile design, examining two primary methodologies: Limit Equilibrium Methods (LEM) and Soil-Structure Interaction Methods (SSIM). While LEM methods, grounded in classical principles, provide valuable insights for preliminary design considerations, they may encounter limitations in addressing real-world complexities. In contrast, SSIM methods, including the SSI-SR approach, introduce precision and depth to the field. By employing numerical techniques such as Finite Element (FE) and Finite Difference (FD) analyses, these methods enable engineers to navigate the dynamics of soil-structure interaction. The exploration extends to SSI-FE, highlighting its essential role in civil engineering. By integrating Finite Element analysis with considerations for soil-structure interaction, the SSI-FE method offers a holistic understanding of how structures dynamically interact with their geotechnical environment. Throughout this exploration, the study dissects critical components governing SSIM methods, providing engineers with tools to navigate the intricate landscape of geotechnical design. The study acknowledges the significance of the Mohr-Coulomb constitutive model while recognizing its limitations, and guiding practitioners toward informed decision-making in geotechnical analyses. As the article concludes, it underscores the importance of continuous learning and innovation for the future of geotechnical engineering. With advancing technology and an evolving understanding of soil-structure interaction, the study remains committed to ensuring the safety, stability, and efficiency of geotechnical structures through cutting-edge design and analysis techniques.

Band structure calculation of scalar waves in two-dimensional phononic crystals based on generalized multipole technique

A multiple monopole （or multipole） method based on the generalized mul- tipole technique （GMT） is proposed to calculate the band structures of scalar waves in two-dimensional phononic crystals which are composed of arbitrarily shaped cylinders embedded in a host medium. In order to find the eigenvalues of the problem, besides the sources used to expand the wave field, an extra monopole source is introduced which acts as the external excitation. By varying the frequency of the excitation, the eigenvalues can be localized as the extreme points of an appropriately chosen function. By sweeping the frequency range of interest and sweeping the boundary of the irreducible first Brillouin zone, the band structure is obtained. Some numerical examples are presented to validate the proposed method.

Research progress of precise structural regulation of single atom catalyst for accelerating electrocatalytic oxygen reduction reaction

The development and utilization of renewable clean energy can effectively solve the two major problems of energy and environment. As an efficient power generation device that converts hydrogen energy into electric energy, fuel cell has attracted more and more attention. For fuel cells, the oxygen reduction reaction(ORR) at the cathode is the core reaction, and the design and development of high-performance ORR catalysts remain quite challenging. Since the microenvironment of the active center of single atom catalysts(SACs) has an important influence on its catalytic performance, it has been a research focus to improve the ORR activity and stability of electrocatalysts by adjusting the structure of the active center through reasonable structural regulation methods. In this review, we reviewed the preparation and structure–activity relationship of SACs for ORR. Then, the structural precision regulation methods for improving the activity and stability of ORR electrocatalysts are discussed. And the advanced in-situ characterization techniques for revealing the changes of active sites in the electrocatalytic ORR process are summarized. Finally, the challenges and future design directions of SACs for ORR are discussed. This work will provide important reference value for the design and synthesis of SACs with high activity and stability for ORR.

Shape optimization of plate with static and dynamic constraints via virtual laminated element

The virtual laminated element method (VLEM) can resolve structural shap e optimization problems with a new method. According to the characteristics of V LEM , only some characterized layer thickness values need be defined as design v ariables instead of boundary node coordinates or some other parameters determini ng the system boundary. One of the important features of this method is that it is not necessary to regenerate the FE(finite element) grid during the optimizati on process so as to avoid optimization failures resulting from some distortion grid elements. Th e thickness distribution in thin plate optimization problems in other studies be fore is of stepped shape. However, in this paper, a continuous thickness distrib ution can be obtained after optimization using VLEM, and is more reasonable. Fur thermore, an approximate reanalysis method named ″behavior model technique″ ca n be used to reduce the amount of structural reanalysis. Some typical examples are offered to prove the effectiveness and practicality of the proposed method.

LARGE DEFLECTION ANALYSIS OF RECTANGULAR PLATES BY COMBINED PERTURBATION AND FINITE STRIP METHOD

The perturbation method and finite strip method are combined to solve the large deflection bending problems of rectangular plates. Perturbation method is used to reduce the nonlinear differential equations into a series of linear differential equations. The finite strip method is then employed to tackle these linear equations. Some calculation examples are compared with those got by other methods.

Research progress on multiscale structural characteristics and characterization methods of iron ore sinter

At present,blast furnace ironmaking is still the main process for producing molten iron,and sinters are the main raw material for blast furnace ironmaking.A sinter with good metallurgical performance can not only ensure smooth operation of the blast furnace but also reduce the blast furnace fuel ratio and increase the molten iron production.Structure is the most important factor affecting the metallurgical properties of the sinter.Thus,the research progress of sinter pore and mineral phase structures was reviewed and the mechanism by which they influence sinter properties was expounded.Multiscale characterization methods for the sinter and their advantages and disadvantages were introduced,and the future research direction of sinter was discussed.

垂直电性源瞬变电磁监测在典型地质构造中的应用

矿井地层中存在的地质构造易引起地质灾害的发生,对矿井安全生产造成极大威胁。为提高瞬变电磁法探测精度与探测范围,以电磁场扩散理论为基础,运用正演模拟方法,分析了垂直电性源瞬变电磁场的响应曲线衰减规律,设计了矿井地质构造致灾区垂直电性源在线监测系统,并模拟了垂直电性源TEM对典型断层地质构造的识别能力。结果表明:当发射源长度为1 000 m时,可监测的偏移距离在500~4 500 m,监测深度可达2 000 m,可以满足地质构造的探测需求。感应电动势与电场的六分量在平面图中均可对断层地质构造进行有效识别,其中z方向分量的识别效果最好。在衰减曲线图中,dBx/t与dBy/t对于断层的识别能力较弱,而其余的四个分量均可对断层构造进行有效识别。

两种方法制备微晶玻璃的介电与储能特性的影响

作为一种有潜质的电介质材料,微晶玻璃材料得以广泛研究。目前开展的相关研究都聚焦于材料体系与结构的优化,而有关制备工艺对性能的影响鲜有报导。本研究在之前工作基础上,系统性的研究了熔融法与烧结法两种不同的制备工艺对磷酸盐体系微晶玻璃的结构、介电与储能特性的影响。结果表明,采用熔融法所制备的微晶玻璃具有更有序的显微结构,同时获得了更高的介电常数和更低的介电损耗,兼具最佳的能量释放特性与能量效率的特性。

裸藻多糖超声碱提工艺优化、结构表征及抗氧化活性研究

该文探究了裸藻多糖(Euglena gracilis polysaccharide,EGP)的提取率、结构表征及体外抗氧化活性。采用超声碱提工艺结合Plackett-Burman和响应面设计对EGP提取率进行优化,采用凝胶渗透色谱、离子色谱、傅里叶变换红外光谱、扫描电镜和自由基清除实验对EGP的分子质量、单糖组成、基团构成、微观结构和抗氧化活性进行分析。超声碱提法用于EGP提取的最佳工艺参数为料液比为1∶40(g∶mL),水浴温度为41℃,水浴时间为0.9 h,NaOH溶液浓度为1 mol/L,超声功率为120 W,超声时间为3 min,在此条件下,EGP的提取率为(62.84±0.49)%。结果表明,EGP由100%葡萄糖组成,通过β-糖苷键连接,分子质量为2.13×10^(4)Da。抗氧化实验结果表明,EGP对羟自由基、DPPH自由基、ABTS阳离子自由基、超氧阴离子自由基均表现出良好的抗氧化活性。EGP的结构研究为裸藻的继续开发利用提供了科学的理论依据。

沥青混合料中集料迁移的表征方法与评价指标综述

集料作为沥青混合料的主要组成部分,通过表征其在混合料中的迁移特性来量化其形态特征和粒径对沥青混合料性能的影响,对研究混合料细观结构变化及预估路面变形类病害有重要意义。目前,表征不同形态特征和粒径集料迁移特性方法的系统性研究仍有待完善。为评述不同集料迁移特性的表征方法与评价指标,本文对表征集料形态特征及粒径分布的传统试验、图像、数值仿真方法进行总结;从数字图像处理、传感器、离散元方法等角度,对现有追踪不同集料迁移及分布特征的光学扫描设备、算法、传感器、软件种类及适用范围等进行对比;通过分析可量化集料迁移特性的空间位移、空间旋转角、欧拉角、加速度、位移增量等17种指标,对混合料中不同集料颗粒运动规律的评价方法进行研究。最后,基于现有表征和评价不同集料迁移特性方法和指标的不足,对未来研究沥青混合料细观结构的方法和评价指标进行展望。

压汞法和液氮吸附法在高阶煤孔隙结构表征中的适用性

沁水盆地南部煤储层是中国典型的高阶煤储层,也是我国煤层气开采的重要基地,其煤孔隙结构表征对煤层气开采、CO_(2)封存及瓦斯突出危险性评价等至关重要。选取沁水盆地样品,采用压汞法和液氮吸附法分别对煤样孔径分布和孔隙形态进行了测试计算。结果表明:相比压汞法,氮气吸附法所测孔体积随孔径的变化率随孔径增加而缓慢上升,孔径所对应的dV/dlgD-D值低,其结果更符合高阶煤微小孔径特征;对比采用压汞法和液氮吸附法所测试的孔隙形态,并结合测量孔径值和典型矿区高阶煤孔隙特点,发现采用液氮吸附法所测得的孔隙形状可以更好地表征高阶煤微小孔径特点。因此,高阶煤孔径5~50 nm孔隙结构表征宜采用液氮吸附法。该研究结果为沁南盆地南部高煤阶孔隙结构精细表征提供了理论依据和实践经验。

孔隙结构对黏土持水性及抗剪强度的影响

为研究双峰孔隙结构对非饱和土力学特性的影响,以广西南宁和桂林2种典型双峰孔隙结构黏土为研究对象,分析了其在不同饱和度情况下的抗剪强度特性;辅以滤纸法及核磁共振(nuclear magnetic resonance,NMR)技术探究了2种土体在双峰孔隙结构情况下孔隙水分布状态对强度的影响机理。结果表明:饱和状态下,2种土体试样的T2分布曲线为双峰结构,且土样持水特性整体上均呈现双峰土水特征曲线;2种土体的应力-位移关系变化规律相似,抗剪强度与饱和度密切相关;在饱和度为40%前后土样黏聚力变化趋势发生改变,而内摩擦角则是在饱和度为80%时达到最小值。

超声辅助复合酶法提取板栗仁中可溶性膳食纤维工艺优化及其结构表征

以燕山板栗为原料,采用超声辅助复合酶法提取板栗膳食纤维。通过单因素试验考察复合酶(m(α-淀粉酶)∶m(糖化酶)=4∶1)添加量、中性蛋白酶添加量和超声波处理时间对板栗膳食纤维得率的影响,设计响应面试验对酶解工艺中各影响因素进行优化,并采用扫描电镜、红外光谱和热质量分析对其结构进行表征。结果表明,以板栗的质量计量,超声辅助复合酶法提取膳食纤维最佳条件为:复合酶添加量为11%,中性蛋白酶添加量为4%,超声波处理时间15 min。在此条件下,板栗膳食纤维得率为22.22%。扫描电镜显示板栗膳食纤维呈现松散的片状或层状结构,表面具有较多的孔洞。红外光谱显示其具有膳食纤维的特征吸收峰。热质量分析板栗膳食纤维适合在400℃以下温度加工。超声辅助复合酶法能有效用于板栗中膳食纤维的提取。

国外固体火箭发动机药柱结构完整性评估技术发展及启示

药柱结构完整性评估对于固体火箭发动机的设计和使用维护至关重要。文章第一部分以二十年为一个阶段,回顾了美国从20世纪50年代到本世纪初药柱结构完整性评技术的发展历史。每个阶段按发展重点,从黏弹性理论分析、强度失效、试验测试方法、药柱状态监测及老化性能研究等角度进行了概述,分析了技术演变过程和相互关系。第二部分,分析了美国药柱结构完整性评估技术发展历程对固体推进剂性能试验技术、固体推进剂数值方法、失效评估及寿命预估四个关键问题研究带来的启示,讨论了固体推进剂及粘接界面性能表征方法、多尺度本构与仿真技术、高精度失效评估与寿命预测、药柱结构验证性试验技术以及跨学科方法的发展趋势。

Characterization Methods for Azobenzene Photoisomerization Energy Storage: A Review

The development of azobenzene photoisomerization materials marks a pivotal advancement in solar-thermal conversion technologies.Their properties and performance,explored through comprehensive characterization,are vital for further progress.Despite extensive research in this area,a detailed summary of characterization methods for azobenzene materials remains largely unexplored.This review addresses this gap by detailing structural and performance characterization techniques.It provides an in-depth overview of various experimental methods,highlighting their objectives,operational mechanics,and practical applications.This detailed review sheds light on the complex relationship between the materials'structure and their performance.Moreover,the review presents a critical analysis of these methods,assessing their strengths and limitations.By doing so,it highlights the revolutionary potential of azobenzene materials in the realm of solar energy conversion and underscores their significance in fostering sustainable energy solutions.

单原子催化剂的制备与分析方法的研究进展

单原子催化剂(SACs)因负载的金属单原子分散在适当载体表面,不仅最大限度地提高了金属原子的利用效率,还可以调节催化反应活性和选择性,具有性能优异、成本低、催化活性高的优点。本文介绍了单原子催化剂目前常用的主要制备方法,如共沉淀法、原位生长法、水热合成法、湿浸渍法等。阐述了单原子催化剂的电子显微镜、同步辐射表征、密度泛函理论(DFT)计算等表征方法,以反映其结构和化学状态。讨论了单原子Ag催化剂和单原子Fe催化剂对水中典型有机物的降解性能。最后,对单原子催化剂新的研究方向和未来发展趋势进行了探讨。

针对双目摄像技术的岩体结构面非接触调查评述

为准确评估岩体质量的优劣,以及了解其在稳定性方面的差异,进行岩体质量分级工作是必要的,其中最关键的部分是调查岩体的结构面。现阶段,对于岩体质量分级中的岩体结构面的调查方法主要有现场接触法、钻孔测量以及非接触扫描测量3类方法。随着科技发展,基于双目摄像技术的岩体结构面非接触调查法在识别准确率上有质的提升,同时大大节省人力物力成本。该文结合基于双目摄像技术的岩体结构面非接触调查法的基本原理、采集过程及数据处理过程对这项技术进行详细介绍,同时通过应用实例对该技术的实用性进行评述。该技术符合现场实际条件,能够快速评价岩体质量,为矿山企业提供重要依据来选择工程结构参数,并有效指导生产。

既有建筑混凝土结构加固改造技术应用与管理

在城市更新的进程中,减少新建工程对资源土地的浪费,推进既有建筑的升级改造当前已成为建筑行业的大趋势。既有建筑混凝土结构加固工程中加固方式的选择和技术应用是此类工程的难点和重点,需经过对原有结构检测和设计单位反复验算论证后,才能确定科学可行的加固方式。目前应用较广泛的加固方式有改变结构形式、加大构件截面尺寸、植筋法、粘贴钢板、碳纤维布加固等。实际工程应用中往往通过这几种方式的结合才能取得良好的效果,满足建筑的使用功能。论文结合实际工程案例浅述既有建筑结构加固技术在工程中的应用和管理,为同行业提供参考。