Hydroxyapatite/tricalcium silicate composites cement derived from novel two-step sol-gel process with good biocompatibility and applications as bone cement and potential coating materials

Tricalcium silicate (C₃S) and hydroxyapatite (HAp) composites were fabricated through the sol-gel process. The aim of this research is to improve the biocompatibility of C₃S through HAp addition and study the potential of using this as coating materials. The composites (HAp/C₃S) were characterised by Fourier transform infrared spectrometry, thermal gravity-differential thermal analysis and X-ray diffraction. The working and setting times of cement pastes were tested using Gillmore needle. Mechanical properties were examined by nanoindentation and material testing system. In vitro biocompatibility of the materials were studied by cell attachment and viability of L929 and MG-63 cells. HAp/C₃S as a coating material on gelatin film were measured with the surface roughness and imaged by scanning electron microscope. With the addition of HAp, no undesirable free CaO was detected with the synthesis by the sol-gel preparation. The pH values of HAp added groups were between 7.54 and 8.76, which were much lower than pure C₃S group (pH?=?11.75). For in vitro studies, the presence of HAp could effectively enhance the cell attachment and viability of both L929 and MG-63 cells grown in the extract or directly on the composites. However, the mechanical properties of the composites were impaired as compared to pure C₃S. Lastly, HAp/C₃S cement could be evenly coated on gelatin film. HAp is successfully demonstrated to improve C₃S biocompatibility with this new composites HAp/C₃S. C-75 (75% C₃S and 25% HAp), in particular, has good biocompatibility, relatively high compressive strength and can be uniformly coated onto gelatin film. Thus, C-75 is a promising material for further investigation as a coating on other biopolymers.     

CAN总线的输送控制系统集成化研究

针对现有技术中输送系统控制不稳定、控制能力低下等问题,本文提出基于工业CAN总线的输送系统集成化控制.在控制系统CAN通信节点利用代码进行数据的转化,通过emit关键字将数据绘制成显示曲线,由输入的代码不断对系统数据进行刷新,实现了输送系统的实时监控,提高了系统运行的安全性.通过时间同步技术将SAEAS6802时钟同步协议与时钟修正算法相结合,有效地对数据处理时间和接收时间进行校正,减少了数据接收误差,提高了时间同步精度.实验结果表明,本文研究方法提高了输送控制系统的运行安全性和可靠性.     

Improving the initialization speed for long-range NRTK in network solution mode

Initialization speed is one of the most important factors in network real time kinematic (NRTK) performance. Owing to the low correlation among the error s     

Enhance cycling performance of LiMn2O4 cathode by Sr2+ and Cr3+ doping

Spinel LiSr_0·1Cr_0·1Mn_1·8O₄ was synthesised by high temperature solid state method in order to enhance the electrochemical performance. The LiSr_0·1Cr_0·1Mn_1·8O₄ (LSCMO) materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests. The XRD and SEM studies confirm that LSCMO had spinel crystal structure with a space group of Fd3m, and the particle of LSCMO shows irregular shape. The cyclic voltammetry data illustrated that the heavy current charge–discharge performance of LMO was improved by Sr²⁺ and Cr³⁺ doping. The galvanostatic charge–discharge of LSCMO cathode materials was measured at 1, 5, 10 and 20 C. The results indicated that LSCMO improved the capacity retention.     

Microstructural and electrical changes in Ca0.9R0.1CeNbMoO8 (R = Y,Sm, Nd,La) ceramics induced by rare-earth ion doping

Rare-earth ions doped Ca_0.9R_0.1CeNbMoO₈ (R = Y, Sm, Nd, La) ceramics have been successfully prepared by solid-state method, and their modifications to the microstructure and electrical properties are also investigated. The rare-earth ions doped ceramics exhibit the scheelite structure. With the increase in the radius of rare-earth ions, the lattice distortion and bond interaction will be enhanced, and the consistency of grain size will be reduced. The ceramics exhibit negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K-1273 K, and the activation energy decreases with the increase of the radius of rare-earth ions. Rare-earth ions doping can increase the content of Ce³⁺ ions and promote the conductivity of ceramics. Except for Sm³⁺-doped ceramics, the high-temperature aging rate of other ceramics is less than 2%. The existence of some metastable Sm²⁺ ions in Sm³⁺-doped ceramics not only increases the activation energy, but also reduces the high-temperature stability of the ceramics.