汶川地震昭化古城历史建筑震损调查与分析

基于汶川地震后昭化古城210处历史建筑震害调研,对古城木结构、生土结构、石结构历史建筑进行了震损统计与机理分析。昭化古城93.8%的历史建筑为木结构,多采用穿斗木承重构架与竹编夹泥围护墙的结构形式,在汶川地震中表现出了良好的抗震性能。木结构历史建筑的震损形式主要有榫卯连接破坏、木柱折断、柱脚滑移等,土结构历史建筑震损形式主要有承重生土墙的开裂或垮塌、掉瓦、屋架倾斜等,石结构门楼历史建筑共计三处均为轻微破坏,震损形式主要有雉堞震损、拱券开裂及边缘城墙震裂或局部倒塌。     

Influence of Zr/Ti atomic ratio and seed layer on the magnetoelectric coupling of Pb(ZrxTi1−x)O3 film-on-CoFe2O4 bulk ceramic composites

Lead zirconate titanate Pb(Zr_xTi_1−x)O₃ films with various Zr/Ti ratios of 20/80, 40/60, 52/48, 60/40 and 80/20 are deposited on highly dense CoFe₂O₄ ceramics using a simple chemical solution deposition. All Pb(Zr_xTi_1−x)O₃ films are polycrystalline and have no preferential orientations. The dielectric, ferroelectric, piezoelectric and magnetoelectric properties strongly depend on the Zr/Ti ratio. And the Pb(Zr_xTi_1−x)O₃ films with a Zr/Ti ratio close to morphotropic phase boundary exhibit best properties, whose magnetoelectric coefficient is over 1.5 times larger than those of other Zr/Ti ratios. The introduction of a PbO seeding layer between the Pb(Zr_0.52Ti_0.48)O₃ films and CoFe₂O₄ substrates facilitates the (100)-texture. Therefore, the magnetoelectric coefficient was enhanced by 1.5 times. The further improvement of the magnetoelectric coupling could be anticipated by fabricating Pb(Zr_0.52Ti_0.48)O₃ films with more or absolute (100)-texture and using conductive interfacial layer between two phases.     

Preparation of refractory cordierite using amorphous rice husk silica for thermal insulation purposes

This study aims to investigate the effect of sintering temperatures on the phase formation and physical characteristics of refractory cordierite prepared from rice husk silica, Al₂O₃, and MgO powders. The samples were subjected to sintering temperatures of 1050–1350 °C, and development of structures was characterized using Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) coupled with Rietveld analysis, scanning electron microscopy (SEM) and dilatometry. The results obtained indicated the significant role of sintering temperatures on phase transformation of spinel and cristobalite into cordierite, in which at sintering temperatures of 1230–1350 °C the cordierite emerges as a dominant phase, while spinel and cristobalite are practically undetected. Formation of cordierite was followed by decrease in density, porosity, and thermal expansion coefficient, while for hardness and bending strength the opposite was true. Thermal expansion coefficient of the sintered sample at 1350 °C is 3.3×10⁻⁶/°C and the XRD analysis demonstrated that the main crystalline phase is cordierite. Based on these characteristics, the samples are considered as insulator, suggesting their potential use in refractory devices.     

High temperature interfacial phase stability of a Mo/Ti3SiC2 laminated composite

A Mo/Ti₃SiC₂ laminated composite is prepared by spark plasma sintering at 1300 °C under a pressure of 50 MPa. Al powder is used as sintering aid to assist the formation of Ti₃SiC₂. The fabricated composites were annealed at 800, 1000 and 1150 °C under vacuum for 5, 10, 20 and 40 h to study the composite's interfacial phase stability at high temperature. Three interfacial layers, namely Mo₂C layer, AlMoSi layer and Ti₅Si₃ solid solution layer are formed during sintering. Experimental results show that the Mo/Ti₃SiC₂ layered composite prepared in this study has good interfacial phase stability up to at least 1000 °C and the growth of the interfacial layer does not show strong dependence on annealing time. However, after being exposed to 1150 °C for 10 h, cracks formed at the interface.     

Microorganisms in flotation and flocculation: Future technology or laboratory curiosity?

That microorganisms, both living and dead, and products derived from the organisms, can function as flotation agents and flocculation agents is abundantly clear. They can modify the surfaces of minerals. They can function as flotation collectors and as flotation depressants and activators. In many cases they or their products can function as specific flocculation agents.Problems that must be solved before such microorganisms or products from the organisms can be used in commercial operations include culturing the organisms at a cheap cost and reduction in dosages required for various separations. These tasks are formidable. However, the concept of using such natural materials in place of various chemical reagents that may be toxic is very attractive. An attempt is made to show some of the promise of microorganisms in mineral bioprocessing and to consider the problems that must be overcome before commercial application of the technology is realized.     

烷基季铵阳离子改性制备有机粘土的研究及应用进展

蒙脱石是属于2∶1型层状硅酸盐类粘土矿物,具有优异的物理化学性能。近年来,烷基季铵盐改性的有机膨润土作为一种新型的化学、化工原料在环境保护和新材料等应用方面引起了广泛的关注并且已成为当前材料科学的研究热点之一。本文概括了蒙脱石、烷基季铵盐的结构特征;阐述了有机膨润土的制备原理及合成工艺;介绍了有机蒙脱石的表征技术和现阶段研究成果;最后对有机粘土应用及发展前景进行了概述和展望。     

一种空空导弹复合制导交接班方案设计

首先分析空空复合制导交接班的特点以及交接时间点。然后结合具体的制导律,设计一种与不同的中段制导律、末段制导律匹配的空空复合制导交接班方案,实现中段制导和末段制导的平滑过渡,确定交接时间点。最后经理想制导系统仿真,验证了方案的有效性。     

Rapid preparation of Bi0.5Na0.5TiO3 ceramics by reactive flash sintering of Bi2O3-NaCO3-TiO2 mixed powders

Lead-free Bi_0.5Na_0.5TiO₃ piezoelectric ceramics were successfully prepared by reactive flash sintering of Bi₂O₃-NaCO₃-TiO₂ mixed powders, where phase transformation and densification occurred simultaneously. The influence of electric field strength, current density and holding time at constant current state on the phase transformation and densification were investigated. The current density had a significant influence on the extent of phase transformation and densification. The holding time had no influence on the phase transformation, but had an important effect on crystallinity of sample. The sintered bulks exhibited the maximum polarization P_m of 16.8 μC/cm², remanent polarization P_r of 9.6 μC/cm², coercive field E_c of 29 kV/cmm, maximum electric-field-induced strain of 0.053 %, and piezoelectric coefficient d₃₃ of 85 pC/N. The reactive flash sintering can prepare the dense and single-phase ceramics from multiphase precursor powders in one step of flash, providing a new way for rapid production of ceramic materials.     

Response of structure and mechanical properties of high entropy pyrochlore to heavy ion irradiation

Material with superior damage tolerance, chemical durability, and structure stability is of increasing interest in high-level radioactive waste management and structural components for advanced nuclear systems. In this paper, high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇ with pyrochlore-type structure was synthesized through conventional solid-state method. The as-synthesized high-entropy oxide maintained crystalline after being irradiated by using Au³⁺ with 9.0 MeV energy at the fluence of 4.5 × 10¹⁵ ions·cm^-2, indicating its high tolerance to heavy-ion irradiation. The irradiation-induced order-disorder transition from pyrochlore structure to defective fluorite structure occurred in high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇. After irradiation, no irradiation-induced segregation was observed at grain boundary. Moreover, the mechanical properties of high-entropy pyrochlore were improved. The heavy-ion irradiation resistance mechanisms of high-entropy pyrochlore were discussed in detail. Our work identified high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇ can be a promising candidate for immobilization of high-level radioactive waste as well as advanced nuclear reactor system from the perspective of irradiation resistance.     

Enhanced Mn2+ solidification and NH4+-N removal from electrolytic manganese metal residue via surfactants

Electrolytic manganese metal residue (EMMR) harmless treatment has always lacked a low-cost and quick processing technology. In this study, surfactants, namely tetradecyl trimethylammonium chloride (TTC), sodium dodecyl benzene sulfonate (SDBS), sodium lignin sulfonate (SLS), and octadecyl trimethylammonium chloride (OTC), were used in the solidification of Mn²⁺ and removal of NH₄⁺-N from EMMR. The Mn²⁺ and NH₄⁺-N concentrations under different reaction conditions, Mn²⁺ solidification and NH₄⁺-N removal mechanisms, and leaching behavior were studied. The results revealed that the surfactants could enhance the Mn²⁺ solidification and NH₄⁺-N removal from EMMR, and the order of enhancement was as follows: TTC > SDBS > OTC > SLS. The NH₄⁺-N and Mn²⁺ concentrations were 12.3 and 0.05 mg·L^-1 with the use of 60.0 mg·kg^-1 TTC under optimum conditions (solid–liquid ratio of 1.5:1, EMMR to BRM mass ratio of 100:8, temperature of 20 ℃, and reaction duration of 12 h), which met the integrated wastewater discharge standard (GB8978-1996). Mn²⁺ was mainly solidified as Mn(OH)₂, MnOOH and MnSiO₃, and NH₄⁺-N in EMMR was mostly removed in the form of ammonia. The results of this study could provide a new idea for cost-effective EMMR harmless treatment.