尿素共沉淀法制备纤维状羟基磷灰石/壳聚糖复合粉料

尿素共沉淀法制备纤维状羟基磷灰石/壳聚糖复合粉料;壳聚糖; 羟基磷酸钙; 尿素共沉淀     

微米级硫酸钙晶须的制备

为了制备分布均一、具有较好光滑性和长径比的微米结构二水硫酸钙(CaSO4.2H2O)晶须,在室温条件下,以CaCl2和(NH4)2SO4为主要原料,通过一步超声反应制备出具有比较理想结构的微米级二水硫酸钙晶须。研究发现,在硫酸钙晶须生成过程中无水乙醇的量起着非常重要的作用,过多、过少的无水乙醇都不利于生成目标产物。CTAB的量对于二水硫酸钙晶须的长径比大小具有较大的调控作用。当无水乙醇的量为20mL,CTAB的浓度为0.9mmol/L,超声时间为1h时可以制备较理想的目标产物。120℃热处理2h晶须变碎,结果与热重结果相一致。与一般的晶体制备不同的是陈化时间对硫酸钙晶须的长径比无影响。通过X射线粉末衍射和热重分析分别对产物的结构和热稳定性进行了表征。结合实验简单探讨了二水硫酸钙晶须生成的机理,从中发现了制备较高长径比的二水硫酸钙晶须的一些规律。     

H2SO4-H2O中硝酸铜对脱硫石膏晶须生长的影响

以处理后的脱硫石膏为原料,在H₂SO₄-H₂O体系中以Cu(NO₃)₂为晶形控制剂采用水热法制备脱硫石膏晶须,探讨了Cu(NO₃)₂对脱硫石膏晶须生长的影响机理。结果表明:Cu(NO₃)₂对脱硫石膏有明显促溶作用,其中Cu²⁺可减小溶液中各离子的活度系数,使溶液中的Ca²⁺浓度增大。NO^-₃通过静电作用在Ca²⁺周围聚集并对SO^2-₄产生屏蔽作用,导致脱硫石膏继续溶解并使Ca²⁺和SO^2-₄的浓度处于相对稳定状态,有利于半水脱硫石膏晶体的形核与生长。此外,Cu²⁺还可在晶须的生长过程中选择性吸附在晶须表面,生成CuSO₄,促进了脱硫石膏的结晶生长,最终在Cu(NO₃)₂用量为2.0%(质量分数)时制备的脱硫石膏晶须长径比约为73。     

Preparation of nano-hydroxyapatite/poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) biocomposite microspheres

Nano-hydroxyapatite (HA)/poly(l-lactide) (PLLA) composite microspheres with relatively uniform size distribution were prepared by a solid-in-oil-in-water (s/o/w) emusion solvent evaporation method. The encapsulation of the HA nanopaticles in microshperes was significantly improved by grafting PLLA on the surface of the HA nanoparticles (p-HA) during emulsion process. This procedure gave a possibility to obtain p-HA/PLLA composite microspheres with uniform morphology and the encapsulated p-HA nanoparticle loading reached up to 40 wt% (33 wt% of pure HA) in the p-HA/PLLA composite microspheres. The microstructure of composite microspheres from core-shell to single phase changed with the variation of p-HA to PLLA ratios. p-HA/PLLA composite microspheres with the diameter range of 2–3 μm were obtained. The entrapment efficiency of p-HA in microspheres could high up to 90 wt% and that of HA was only 13 wt%. Surface and bulk characterizations of the composite microspheres were performed by measurements such as wide angle X-ray diffraction (WAXD), thermal gravimetric analysis (TGA), environmental scanning electron microscope (ESEM) and transmission electron microscopy (TEM).     

TiC晶须的形貌

用气相催化无衬底化学气相沉积法制备TiC高温陶瓷晶须。经X射线物相分析、电子衍射测定和扫描电镜观测。分析了TiC晶须的形貌。     

原位生长高度定向ZnO晶须

采用大气压金属有机化合物化学气相沉积(AP-MOCVD)方法，以Zn(C₅H₇O₂)₂为原料，在玻璃基片上制备出高度定向的ZnO晶须.扫描电子显微镜观察发现晶须垂直基片取向生长，规则排列，长度、形状几乎一致.晶须直径为100nm—800nm,长径比为8—15，尖端曲率半径仅为50nm，甚至更小.x射线衍射(XRD)分析结果表明ZnO晶须为六方晶系纤锌矿结构，并沿c轴高度取向.采用热分析对反应前驱物进行了研究,同时也讨论 关键词： ZnO 取向生长 晶须 MOCVD     

Synthesis of phosphate-type fluorocarbon-hydrocarbon hybrid surfactants and their adsorption onto calcium hydroxyapatite

Five novel phosphate-type hybrid surfactants, C_mF_2m+1C₆H₄CH[OPO₂(OC₆H₅)Na]C_nH_2n+1 (FmPHnPPhNa: m = 4, 6, 8; n = 3, 5; C₆H₄ = p-phenylene, C₆H₅ = phenyl), have been synthesized. When compared with sulfate-type hybrid surfactants, C_mF_2m+1C₆H₄CH(OSO₃Na)C_nH_2n+1 (C₆H₄ = p-phenylene), the new hybrid surfactants are found to have comparable abilities to lower surface tension of water. The critical micelle concentrations of FmPHnPPhNa follow Klevens rule and their occupied areas per molecule increase with increasing m and n. Calcium hydroxyapatite (CaHAp) pellets modified with FmPH3PPhNa gives high hydrophobic and lipophobic surfaces. The hybrid surfactants are expected as new dental reagents for oral hygiene.     

Bioactive Ca10(PO4)6(OH)2−TiO2 composite coating prepared by sol-gel process

The sol-gel prepared titania (TiO₂) has recently been demonstrated with a promising bioactivity [1]. It forms a chemical bond with the living bone in the body, although the bonding is not very strong. The present study is intended to improve the bone-bonding ability of the titania gel. The goal is achieved by impregnating the titania with hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂). The processing route includes the following steps: (1) the titania sol solution was prepared; (2) the solution was mixed with fine hydroxyapatite (HA) powders; (3) the mixture was used to produce a coating on a commercial pure titanium (c.p. Ti) or Ti6A14V plate by a dip coating technique; (4) the coating was fired at 400–600°C. The resulting coating is a composite consisting of hydroxyapatite embedded in the matrix of the titania gel. Such HA-TiO₂ composite coating is capable of inducing the hydroxyapatite precipitation from a simulated body fluid. When implanted in femurs of goat, the composite coating shows a bonding with bone. Its bone-bonding strength is twice as high as that of the pure titania gel coating. The results indicate that impregnating with hydroxyapatite is a promising way to increase the bioactivity of the titania gel.     

SiCw/6061 Al复合材料中界面相的研究

利用电子显微镜分析研究了ＳｉＣ２／６０６１Ａｌ复合材料的界面相。电子衍射分析表明，ＳｉＣｗ／６０６１Ａｌ面相 体心立方结构，点阵常数为１．２８ｎｍ用Ｘ－射线能谱仪测定了界面相的化学成分。     

牛血清蛋白单层膜诱导形成网状结构的羟基磷灰石

0引言近来利用生物矿化的方法来合成具有特殊结构的晶体材料成为材料合成的一个热点[1.2]。羟基磷灰石(HAP)作为一种生物材料,广泛地存在于人和动物的骨骼和牙齿中,是生物矿化的产物。在骨骼的修复、替代和仿生抗菌陶瓷薄膜中有重要的应用[3]。因此,利用生物矿化的方法合成具有