Preparation of Hydroxyapatite Restoration Coating on Enamel Surface and Its Biocompatibility Evaluation

龋病是一种全世界范围内常见的口腔进行性疾病，龋病导致的牙齿功能的丧失严重影响着人们的生活与健康。阻止龋病发展的关键在于对早期龋齿的及时发现和有效的治疗。目前，对于龋病的治疗主要是通过填充从而达到修补龋洞的目的。但这种治疗方式需要磨除部分健康的牙组织，并且由于填充材料与牙齿具有不同的化学成分和微观结构，填充材料与基底之间难以实现完美的结合，在填充以后可能在牙齿与填充材料的界面上发生继发龋。因此，在发生浅龋的牙釉质表面构建与之成分、结构相仿的羟基磷灰石（HA）修复涂层，以达到对早期浅龋无损修复的目的，是解决这一问题的有效途径。 本文基于涂剂法制备牙釉质仿生修复涂层的思路，利用羟基磷灰石粉末在固化...Dental caries is a prevalent chronic and world-wide oral disease. The loss of teeth as a consequence of serious caries greatly reduces the quality of one’s life. The strategy to prevent the development of caries is the effective treatment of early lesions. Currently, enamel defects are frequently refilled with unstructured substitutes. The problems involved in this repair when it is applied to ear...学位：工学硕士院系专业：材料学院材料科学与工程系_材料学学号：2072008115061

牙釉质表面快速修复涂层的制备及其性能研究

以低结晶度羟基磷灰石(HA)粉末与H3PO4/H2O2固化液混合制备糊剂,作用于酸蚀牙釉质表面快速获得修复涂层.通过X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、能谱仪(EDS)、维氏硬度仪对涂层进行表征;采用MTT法和口腔粘膜刺激实验对涂层生物安全性进行初步评价.结果显示,经修复处理15min后的牙釉质表面形成了结构致密的修复涂层,涂层厚度约为10～20μm,其维氏硬度值超过200VHN,细胞毒性为1级,对口腔粘膜无不良刺激反应

Information Code, Abstract and Accounting Standards ——Viewpoint from Information Space Theory

本文从信息空间理论的角度出发,对会计准则的性质进行探讨。在回顾并评价传统解释的基础上,试图得出会计准则“是什么”的一个全新诠释:就静态角度看,会计准则是一种关于企业财务信息编码和抽象的规范体系,其产生根源在于为经济交易的各方提供信息交流和标准化信息转换的平台;就动态角度看,会计准则的变迁则是体系内微观经济个体基于信号发送需要而推动的内涵性变迁和跨体系交易所要求的信息环境共享推动的外延性变迁的共同结果。此外,本文还从会计准则外延性变迁的角度解析了当前各国会计准则存在重大差异的现象。From the point of view of information, this paper tries to explore what accounting standards are. By means of information space theory, it explains the origin and development of accounting standards, while it explains the phenomenon why accounting standards differ in different countrie

Effect of Calcining Process on Crystallization,Morphology and Luminescent Properties of YAG:Ce--(3+) Phosphor Powder Prepared by Polyacrylamide Gel Method

利用高分子网络凝胶法制备yAg:CE3+荧光粉,研究了煅烧温度、煅烧时间等对荧光粉的晶化过程、显微形貌及发光性能的影响。结果表明:高分子网络凝胶法可在1000℃煅烧温度下获得晶型完整的yAg:CE3+荧光粉;随着煅烧温度的升高晶粒尺寸增大,1000℃时平均粒径为50nM,在1300℃时平均粒径为120nM。随温度的升高和粒径的长大其相对发光强度也逐渐提高;随着保温时间的延长,晶粒变化不大,但发光强度逐渐提高,在400MIn时由于CE离子氧化而发生蓝移。Ce-doped YAG phosphor powders were prepared by the polyacrylamide gel method.Effects of calcined temperature and holding time on crystallization and powder morphology as well as luminescent properties of YAG:Ce3+ phosphor powders were studied.The results show that the pure Ce-doped YAG phase was obtained by calcining at 1000 ℃.The grain size grew and the particle agglomeration occurred with the calcining temperature rising up and holding time prolonging; the grain size is about 50 nm for samples calcined at 1000 ℃,and it is about 120 nm for samples calcined at 1300 ℃.The emission intensity increases with the calcining temperature rising up.With the extension of the holding time,the particle has a little change,and the emission intensity gradually increases.At the holding time of 400 min,there is a shift of peaks to shorter wavelengths compared with 300 min