Applications of analytical electron microscopy to guide the design of boron carbide

Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics.     

Characterization of biogenic hydroxyapatite derived from animal bones for biomedical applications

In this work, the viability of producing biogenic hydroxyapatite from bio-waste animal bones, namely bovine (cow), caprine (goat) and galline (chicken), through a heat treatment process has been investigated. The animal bones were locally sourced, cleaned to remove collagen and subsequently heat treated in air atmosphere at different temperatures ranging from 600?°C to 1000?°C. From the range of sintering temperatures investigated, it was found that hydroxyapatite derived from bovine bone showed good thermal stability while those produced from caprine and galline bones exhibited phase instability with traces of tri-calcium phosphate (TCP) being detected after heat treatment beyond 700?°C. The porous nature of the bone samples can be observed from the microstructures obtained and supported by low relative density. Heating the bovine and caprine bones at selected temperatures yielded porous HA body, having hardness values that are comparable with human cortical bone. However, the sintered galline bone sample showed higher porosity levels and low hardness when compared to the other two bone types.     

β-Selective C−H Arylation of Electron-Deficient Thiophenes,Pyrroles, and Furans

A general β-C−H arylation of electron-deficient thiophenes, pyrroles, and furans has been developed using ligand-modulated palladium catalyst. The use of a modified norbornene is crucial for reversing the conventional α-selectivity of these substrates. This method features good yields, high β-selectivity, and good tolerance of functional groups.     

Combination of double and single cyclic pressure alternation technique to increase CO2 sequestration with heat mining in enhanced geothermal reservoirs by thermo-hydro-mechanical coupling method

The rise in global temperature due to an unceasingly increase in non-condensable gases (NCG) prompts more development of safe and economical CCUS (Carbon Capture Utilization and Storage) technologies. Carbon dioxide (CO₂) sequestration with heat mining in deep enhanced geothermal systems (EGSs) is one of the promising methods to reduce CO₂ emitted to the atmosphere. In this study, a cyclic alternation of pressures at the injection and production wells is applied in an EGS for heat mining together with CO₂ deposit. Simultaneous alternation of the injection and production pressures can significantly increase the amount of CO₂ sequestrated compared to applying a fixed pumping or withdrawing pressures at the injector and producer respectively. At the injection well, alternation in pumping pressures at high frequency (small interval of days) increased CO₂ sequestration rate. Reducing the pumping frequency resulted in the lowering of the total amount of CO₂ sequestrated, lesser than using a fixed pumping pressure. The alternation in pumping frequency has a direct relationship to the CO₂ sequestration rate. The frequency of the injection and production pressures refers to the interval in days of the interchange in pressure between high to a low value and vice-versa. Furthermore, simultaneous alternation of pressures at the injection and production wells respectively (double cyclic method) improved geothermal heat extraction efficiency, thus higher performance for both geothermal and CO₂ sequestration projects.     

Addressing amorphization and transgranular fracture of B4C through Si doping and TiB2 microparticle reinforcing

Over the last two decades, many studies have contributed to improving our understanding of the brittle failure mechanisms of boron carbide and provided a road map for inhibiting the underlying mechanisms and improving the mechanical response of boron carbide. This paper provides a review of the design and processing approaches utilized to address the amorphization and transgranular fracture of boron carbide, which are mainly based on what we have found through 9 years of work in the field of boron carbides as armor ceramics.     

Multimedia Services for Highway Infrastructure Management

Photographic logging systems used by highway agencies provide engineers with information in the analysis of traffic accidents, design improvements, and highway pavement management. However, there exist limitations for such systems in the areas of accessibility, search capability of the image library, and synchronization video data with traditional engineering site data. More important, there are situations in which multiple users may need to examine the video footage at the same time. This capability cannot be provided by current systems. The analog nature of the video signals also presents difficulties in integrating the visual information with other types of data. This paper introduces a type of multimedia service that can be applied in a state highway department environment for highway infrastructure management. This multimedia‐based information system utilizes state‐of‐the‐art technologies in digital video, high‐speed networking, and video server. This paper discusses the requirements of high‐speed networking systems and presents a new computer network that has the potential to become a dominant technology for the transmission of multimedia data. In addition, design concerns regarding the video server and its structure are also discussed. A data‐synchronization algorithm is also presented on how to dynamically display digital video frames with traditional engineering data sets that contain information such as as‐built data, pavement condition and performance, traffic safety, geometric features, and other infrastructure data.     

重庆购房户住宅需求取向分析

为了解决重庆房地产市场住宅市场供求不平衡这一个难题,我们提出了住宅产业化这个方案,但是在大规模的生产产业化住宅以前,首先必须知道重庆市居民对住宅的需求取向,正是因为这个原因,我们进行了一次问卷调查。问卷调查的目的是：摸清影响重庆市潜在购房户购房行为的因素,为重庆住宅产业化工程的实施构建一个模型。因此本文的目的就是：分析影响重庆市潜在购房户购房行为的因素,找出本市居民喜欢的住宅类型,我们研究组的总体研究目的是：立足于本地的资源,探索在重庆实施住宅产业化工程的可行性,如果可行,那么我们将在充分利用本地建筑材料的基础上,设计出切实可行的产业化住宅模型。在目前这个阶段,工作的重心是摸清重庆建筑业的概况,为下一步的研究铺平道路。而本文的中心是：找出本市居民喜欢的住宅类型。     

Effect of Alumina on the Structure and Mechanical Properties of Spark Plasma Sintered Boron Carbide

Uniform densification of relatively thick (~7 mm) consolidated boron carbide plates at relatively low temperatures (e.g. 1800°C) and low facture toughness are two of the primary challenges for further development of boron carbide applications. This work reports that these two challenges can be overcome simultaneously by adding 5 wt% alumina as a sintering aid. Nearly fully dense (97%), fine grained boron carbide (B₄C) samples were produced using spark plasma sintering at 1700°C and above in the B₄C‐5 wt% Al₂O₃ system. The alumina and boron carbide matrix reacted to form an Al₅O₆BO₃ (a mullite‐like phase) during sintering. The Al₅O₆BO₃ phase facilitated uniform densification via liquid phase sintering. This secondary phase is dispersed throughout the intergranular pores, providing obstacles for crack propagation and resulting in tougher boron carbide ceramics.