Dependence of crystal structure on mechanical and thermophysical properties of magnetoplumbite-type LnMgAl11O19 ceramics with substitution of Ln3+ Ions

Lanthanum hexaaluminate is a promising candidate to establish yttria partially stabilized zirconia as a thermal barrier coating material for super alloy due to their remarkable stability and thermophysical performance. In order to understand the relationship between the structure and properties and gain new low thermal conducting materials, the LnMgAl₁₁O₁₉ (LnMA, Ln: La, Pr, Nd, Sm, Eu, Gd) materials were synthesized firstly and further used to produce the LnMA ceramics. With the increasing relative atomic mass of the replaced Ln³⁺ ions from La to Gd, the lattice parameters and grain sizes of the LnMA platelets decrease, while the mechanical properties increase, and the thermal physic properties decrease. The GdMgAl₁₁O₁₉ ceramics obtain the lowest thermal conductivity with the value of 1.91-1.78 W/m K in the range from room temperature to 800°C, which could be considered as a promising candidate for application in thermal barrier coating materials. These results could further provide reference for developing novel materials lower thermal conductivity.     

Characterization of the Chemical Composition of Chinese Moringa oleifera Seed Oil

This work focused on physicochemical property assaying, fatty acid composition, triacylglycerol (TAG) profiles, and unsaponifiable matter composition of the Chinese Moringa oleifera seed oil. The results indicated that there was no significant difference in approximate nutritional components between M. oleifera seeds from China and India, while variations in the mineral element contents are significant. Both the Soxhlet extraction method and the aqueous enzymatic extraction method were adopted to extract oil from Chinese M. oleifera seeds. Oil yield obtained using the Soxhlet extraction method was higher than that obtained using the aqueous enzymatic extraction method. While both the iodine value and unsaponifiable matter content of the aqueous enzymatic extracted oil were a little higher than that of the Soxhlet extracted oil. Both oils possess a very low acid value and peroxide value, suggesting their good quality as edible oil. Fatty acid composition results indicated that this oil was especially high in oleic acid. Characterization of the TAG composition was achieved by a two-dimensional high-performance liquid chromatography (HPLC) coupling of nonaqueous reverse-phase and silver ion HPLC with the atmospheric pressure chemical ionization mass spectrometry method. A total of 22 TAG including 16 regioisomers were determined. Composition results of unsaponifiable matters revealed that this oil possesses a number of phytosterols, in which β-sitosterol and stigmasterol are most predominant.     

辐照用小尺寸样品力学性能表征技术研究进展

由于辐照空间尺寸限制、降低样品放射性和提高辐照参数精度等原因，小尺寸样品被广泛应用于核反应堆材料的辐照后力学性能表征。本文就国内外小尺寸拉伸、冲击、断裂韧性、疲劳、蠕变和小冲杆等测试表征技术的研究现状进行了综合论述，分析了小尺寸样品测试中的关键影响因素以及数据归一化方法，总结了小尺寸样品存在的问题，并结合我国需求对小尺寸样品技术的发展进行了分析和展望，以期为小尺寸样品技术及测试分析数据进一步规范化和工程应用发展提供参考。     

煤油共炼残渣性质分析

采用元素分析、工业分析、热重、X射线衍射、扫描电镜、红外光谱等手段对煤油共炼残渣的组成、微观结构、官能团进行分析表征，并通过红外谱图的分峰拟合对官能团含量进行半定量计算。结果表明：残渣的有机物由具有片层堆积结构碳质颗粒组成，无机物由煤油共炼催化剂和煤中的无机矿物质组成；残渣颗粒粒径呈10 μm和2 μm的两级分布，颗粒呈整体无序、局部有序的分布状态。分别采用工业分析和热重分析得到挥发分、固定碳和灰分的含量，两组数据一致：残渣的氢键中羟基自缔合结构占到了47.95%；脂肪氢中亚甲基结构占64%左右；含氧官能团主要以碳氧键和羰基形式存在，含有微量的硅氧键，没有羧基；芳香结构中烷基侧链取代基较多，五取代氢的芳香结构只占约4.5%。     

一种酰胺类沥青乳化剂的制备及性能研究

首先通过脂肪酸与酸酐反应，得到多元羧酸中间体，再将其与改性多乙烯多胺经过一系列反应合成一种酰胺类沥青乳化剂，采用傅里叶红外光谱对乳化剂结构进行表征。实验室对比测试了自制乳化剂与进口乳化剂的表面活性及其所制乳化沥青的性能。结果表明：两种乳化剂制备乳化沥青的各项性能指标均可满足微表处施工技术要求，且自制乳化剂具有较高的固含量和较好的储存稳定性，乳化沥青8 min即可破乳，用于微表处养护可快速开放交通；自制乳化剂价格仅为进口乳化剂的76.4%左右，应用前景良好。     

Feasibility study to control fiber distribution for enhancement of composite properties via three-dimensional printing

The distribution of fibers in the composite (which takes into account both their locations and orientations) is one of the important factors that affect the mechanical properties of FRCs. However, this parameter depends on various factors during composite fabrication, and controlling the distribution of fibers in the produced material represents a significant challenge. In this study, the applicability of three-dimensional (3D) printing technique for controlling fiber distributions was evaluated. The fibers fabricated using a 3D printer were placed inside a mold to produce cementitious composites. Three-point bending tests were conducted and the results of the experiment were discussed.     

Progress in pressureless sintering of boron carbide ceramics – a review

ABSTRACT

Boron carbide (B₄C) ceramics has many outstanding performance, such as extremely high hardness, low density, high melting point, high elastic modulus, high thermoelectromotive force, high chemical resistance, high neutron absorption cross section, high impact and excellent wear resistance. Therefore, B₄C ceramics can be used in various industrial applications, such as lightweight ceramic armour, high temperature thermocouples, neutron absorber, reactor control rods in nuclear power engineering, polishing media for hard materials, abrasive media for lapping and grinding, and wear resistant components (blasting nozzles, die tips and grinding wheels). Pressureless sintering is the method with industrialised application value for B₄C ceramics, however, it is impossible to sinter pure B₄C ceramics to high densities without additives by pressureless sintering. So sintering additives must be used to promote the densification of B₄C ceramics. The different sintering additives used to promote the densification of boron carbide will be described in this review, including carbon additives, metallic additives, oxide additives, non-oxide additives, combined additives and rare earth oxide additives. Finally, the recent research trends for sintering methods and sintering additives of B₄C ceramics will also be proposed.     

Extended vertical lists for temporal pattern mining from multivariate time series

In this paper, the problem of mining complex temporal patterns in the context of multivariate time series is considered. A new method called the Fast Temporal Pattern Mining with Extended Vertical Lists is introduced. The method is based on an extension of the level‐wise property, which requires a more complex pattern to start at positions within a record where all of the subpatterns of the pattern start. The approach is built around a novel data structure called the Extended Vertical List that tracks positions of the first state of the pattern inside records and links them to appropriate positions of a specific subpattern of the pattern called the prefix. Extensive computational results indicate that the new method performs significantly faster than the previous version of the algorithm for Temporal Pattern Mining; however, the increase in speed comes at the expense of increased memory usage.