Porous agarose/Gd-hydroxyapatite composite bone fillers with promoted osteogenesis and antibacterial activity

Artificial bone fillers are essentially required for repairing bone defects, and developing the fillers with synergistic biocompatibility and anti-bacterial activity persists as one of the critical challenges. In this work, a new agarose/gadolinium-doped hydroxyapatite filler with three-dimensional porous structures was fabricated. For the composite filler, agarose provides three-dimensional skeleton and endows porosity, workability, and high specific surface area, hydroxyapatite (HA) offers the biocompatibility, and the rare earth element gadolinium (Gd) acts as the antibacterial agent. X-ray photoelectron spectroscopy detection showed the doping of Gd in HA lattice with the formation of Gd-HA interstitial solid solution. Attenuated total reflection Fourier transform infrared spectroscopy imaging suggested chemical interactions between agarose and Gd-HA, and the physical structure of agarose was tuned by the Gd-doped HA. Cytotoxicity testing and alizarin red staining experiments using mouse pro-osteoblasts (MC3T3-E1) revealed remarkable bioactivity and osteogenic properties of the composite fillers, and proliferation and growth rates of the cells increased in proportion to Gd content in the composites. Antibacterial testing using the gram-positive bacteria S. aureus and the gram-negative bacteria E. coli indicated promising antibacterial properties of the fillers. Meanwhile, the antibacterial properties of composite filles were enhanced with the increase of Gd content. The antibacterial fillers with porous structure and excellent physicomechanical properties show inspiring potential for bone defect repair.     

改性剂与矿物填料界面结合关系研究

本文通过对改性矿物填料的热稳定性，红外光谱以及比表面积测定研究，揭示了改性剂与矿物填料的界面结合关系。     

New printing inks with barrier performance for packaging applications: Design and investigation

Barrier properties of packaging materials against moisture and oxygen penetration are of high relevance. Enhanced protection of existing materials against weather conditions can be achieved by application of printed coatings. To improve barrier performance of packaging materials, new inks for obtaining printed coatings with a layered structure were developed and investigated. The proposed ink compositions for flexographic printing on paper substrates are based on an environmentally friendly acrylic binder and contain inorganic fillers with platelet particles incorporated in the polymer matrix. Coatings based on the developed printing inks demonstrate significantly decreased water vapour permeability compared to traditional polymer inks. The effect of decreased permeability was investigated considering inks rheological behaviour, the coating structure, mechanical properties, surface energy and water uptake for different ink formulations. The developed inks provide variable optical properties including coatings with a relatively high transparency. The development of the functional barrier inks contributes to saving natural resources by prolonging life performance of packaging materials and goods.     

常见农药制剂填料的表面性质研究

利用扫描电镜(SEM)、BET比表面积分析仪等手段研究了包括硅藻土、海泡石、高岭土、白炭黑、滑石粉、蒙脱石和玉米淀粉等7种常见农药制剂填料的表面形貌、晶型结构、比表面积和孔容等性质。用不同填料制备了80%烯酰吗啉WDG,比较了不同填料制备的WDG的悬浮率、分散性和崩解性等性能,结果显示用玉米淀粉制备的WDG其物理悬浮率最高,达96.2%。     

350 km/h高速铁路有砟轨道基床结构的技术条件分析

采用车辆轨道路基垂向耦合动力学模型,研究了轨道高低不平顺下有砟轨道路基动力影响系数φ_i的概率分布特性;根据循环荷载下路基粗粒土典型填料单元模型试验反映出的累积变形状态特征与荷载水平的关系,明确了基床以下填料处于无时间效应变形状态、基床填料处于微弱时间效应变形状态的设计工作状态;以基床结构的动强度、长期动力稳定性、循环变形为设计控制指标,开展了高速铁路有砟轨道基床结构的技术条件分析。研究表明:表征路基承受列车动力效应程度的φ_i沿线路纵向服从对数正态分布;列车荷载作用下,路基各结构层的累积变形状态与填料性质密切相关;基床结构的长期动力稳定性为设计主控因素,据此,提出了适用于350km/h有砟轨道高铁基床双层结构型式的技术标准建议。     

Enhanced soft dielectric composite generators: the role of ceramic fillers

A notable issue in the field of dielectric elastomers is the characterization of composite materials with improved electromechanical coupling destined for mechanical-to-electrostatic energy converters. To this aim, random composites, where ceramic fillers with high dielectric constant are dispersed in a silicone matrix, represent an interesting option. Currently, the most promising reinforcing materials to be immersed in a silicone matrix, already tested for soft dielectric actuators, are lead magnesium niobate–lead titanate (PMN–PT) and lead zirconate-titanate (PZT). To estimate the performance improvement entailed by the composite device with respect to the homogeneous matrix, a typical four-phase cycle is considered in the model, where nominal load and electric charge are alternately held constant. Different materials are being studied: a composite consisting of a matrix in poly-dimethyl-siloxane (PDMS) reinforced with PMN–PT, assuming a filler concentration of 10% in volume and a PDMS–PZT composite with a 1% volume fraction of the ceramic component. In comparison with pure PDMS, the PDMS–10%PMN–PT allows an increase of more than 60% in the harvested energy per unit volume, while the PDMS–1%PZT composite, entailing a minor improvement, here in the range 23.5–37.4%, exhibits a better performance in terms of generated energy per unit weight. These results provide a guide for the choice and design of materials suitable for the realization of enhanced energy harvesters.     

Wettability and interfacial reaction mechanism between Ag–Cu alloy and Si3N4 ceramics in air atmosphere

The wetting behaviour and interfacial reaction mechanism between Ag–Cu alloy fillers (with varying copper contents) and Si₃N₄ ceramics using reactive air brazing at 970 °C were systematically investigated. As the copper content increased, the contact angles of the Ag–Cu filler on the Si₃N₄ ceramics decreased. A violent boiling-like interfacial reaction was observed during the experiment, and mass spectrometry analysis identified the gaseous products as N₂, NO and NO₂. The solid products SiO₂ and Cu–O formed at the interface, and the interfacial reactions improved the wettability of the Ag–Cu filler on the Si₃N₄ ceramics. Owing to buoyancy and the pushing of the gases, the interfacial products floated to the surface of the filler and their distribution increased along with the increasing copper content. Two different microstructures were formed at the interface near the triple line. Thick and thin SiO₂ layers were respectively formed on the triple line interface of the fillers with low (Ag–3Cu/Ag–5Cu) and high (Ag–6.6Cu/Ag–16Cu) copper content. The interfacial bonding zones formed in Ag–5Cu, Ag–6.6Cu, and Ag–16Cu samples indicated that the corresponding Ag–Cu fillers were effectively brazed with the Si₃N₄ ceramics.     

真空电子器件用Ga基堵漏钎料的研究

研制成功三种无氧铜真空电子器件堵漏钎料。应用扫描电镜、能谱分析仪、微观硬度仪,研究了三种钎料形成的扩散接头界面连接情况,进行了不同扩散温度下的对比试验。结果表明：三种钎料都能与无氧铜形成良好的相互扩散效果;在三种钎料中,Ga-15In钎料与无氧铜形成的相互扩散效果最好;在不同扩散温度下进行试验,Ga-15In钎料在650℃达到与无氧铜形成的相互扩散效果最佳。     

粉体材料在涂料中的应用技术Ⅰ

涂料用颜填料、粉体助剂和纳米材料统称粉体材料。本文重点介绍不同结构及性能的颜填料组合后的复配改性技术和协同增效技术,有效地提升涂料配方设计水平和涂料产品应用效能,为科学合理地选择颜填料提出了指导性的可操作方法。     

Mechanical and shape‐memory behavior of shape‐memory polymer composites with hybrid fillers

Shape‐memory polymer (SMP) materials have several drawbacks such as low strength, low stiffness and natural insulating tendencies, which seriously limit their development and applications. Much effort has been made to improve their mechanical properties by adding particle or fiber fillers to reinforce the polymer matrix. However, this often leads to the mechanical properties being enhanced slightly, but the shape‐memory effect of reinforced SMP composites being drastically reduced. The experimental results reported here suggested that the mechanical resistive loading and thermal conductivity of a composite (with hybrid filler content of 7.0 wt%) were improved by 160 and 200%, respectively, in comparison with those of pure bulk SMP. Also, the glass transition temperature of the composite was enhanced to 57.28 °C from the 46.38 °C of a composite filled with 5.5 wt% hybrid filler, as determined from differential scanning calorimetry measurements. Finally, the temperature distribution and recovery behavior of specimens were recorded with infrared video in a recovery test, where a 28 V direct current circuit was applied. The effectiveness of carbon black and short carbon fibers being incorporated into a SMP with shape recovery activated by electricity has been demonstrated. These hybrid fillers were explored to improve the mechanical and conductive properties of bulk SMP. Copyright © 2010 Society of Chemical Industry