Study on Electrochemically Controllable Preparation of Nano Hydroxyapapatite Coating and its Formation Mechanism

摘要HA/Ti复合材料可以发挥HA和医用金属的综合优势。已发展了多种制备HA/Ti复合材料的技术，各种方法均有优缺点。电化学沉积法是制备生物陶瓷膜层的一种新方法，其优点是：温和的沉积条件可避免HA晶相的破坏；简单易控的沉积过程易于实现不同性能涂层的可控制备；非线性的涂覆过程，适合于外形复杂的金属基底材料。本文侧重发展电化学沉积法，通过系统研究，实现HA涂层表面形貌结构的可控制备，并探索其结构和性能关系。此外，还对控制条件下羟基磷灰石的电化学沉积机理进行讨论。主要进展和结果如下：1.羟基磷灰石涂层的电化学可控制备发展和完善了从水溶液体系中直接制备结晶完美的纯HA涂层的电化学沉积技术。调节沉积体系...Abstract Hydroxyapatite(HA) coatings can endow the surface metallic materials with bioactivity, thus integrate the proper mechanical properties of the metal substrate with the excellent biological properties of the coating. Many techniques such as plasma spraying, electrophoresis, electrochemical deposition, sol-gel, biomimetic methods, etc. have been developed to prepare HA coatings on metalli...学位：理学硕士院系专业：化学化工学院化学系_物理化学(含化学物理)学号：20022507

Surface Biochemical Modification for the Titanium Implants

综述近年来钛植入体表面生物化学设计和改性的研究进展,重点介绍植入体表面自组装改性新技术及其在生物医用材料中的应用。This paper reviews the progress in biochemical design and modification for the surfaces of titanium implants in recent years,the emphasis being laid on the introduction of the surface molecular construction, self-assembly technique and its application in biomedical materials

Ecotoxicological Effects of Lead and Copper on Seed Germination of Wheat

通过种子萌发试验,研究了不同浓度的Pb2+和Cu2+对小麦种子萌发、幼苗生长以及对小麦α-淀粉酶活性的生态毒理效应。结果表明:Pb2+在低浓度下(5Mg·l-1)对小麦种子萌发过程中的各项指标皆为抑制作用;Pb2+、Cu2+胁迫对小麦α-淀粉酶活性存在低浓度激活和高浓度抑制的效应,且浓度越高,抑制作用越强;Cu2+对小麦种子萌发各项指标的抑制率大于Pb2+,Pb2+、Cu2+对小麦根生长的毒害作用大于对地上部的影响。By seed germination experiments, We studied ecotoxicological effects of Pb2+, Cu2+ on the seed germination, seedling growth and α-amylase activity of wheat.The results showed that the seed germination and seedling growth of wheat could be promoted at low concentrations of Pb2+ (under 0.5 mg·L-1), while they would be inhibited when the concentration of Pb2+ was high; Cu2+ in high concentrations (above 5 mg·L-1) could reduce the germination rate, the seedling growth and vigor markedly; the activity of α-amylase could be enhanced at low concentrations of Pb2+ or Cu2+ but be inhibited at high concentrations, and the injury became severer with the increase of concentration; the inhibition of Cu2+ on seedling growth indices of wheat were larger than that of Pb2+, the stress effects of Pb2+ or Cu2+ was stronger on seed germination than seedling growth.国家高技术研究发展计划(863计划)项目(2007AA10Z441);上海市科委项目(07DZ12055);上海市科委项目(07JC14025

Effects of Cadmium Stress on Seed Germination and Seedling Growth of Dwarf Beans

为比较系统地探讨Cd2+的生物毒性,作者以水培法研究了不同浓度的Cd2+溶液对四季豆种子萌发和幼苗生长发育过程中植物外部生长指标及内部生理生化变化的影响。结果表明:当Cd2+浓度较低时,Cd2+对种子萌发及幼苗生长发育毒害作用较小,一定浓度范围内(0.05~0.5Mg/l)还有促生作用,高浓度Cd2+(5~100Mg/l)能严重抑制四季豆幼苗根及下胚轴的生长;Cd2+胁迫对四季豆幼苗体内过氧化物酶(POd),超氧化物歧化酶(SOd),过氧化氢酶(CAT)活性存在低浓度激活和高浓度抑制的效应,且同一浓度的Cd2+对四季豆幼苗POd、CAT活性的抑制作用表现为根系大于下胚轴,Cd2+浓度>0.5Mg/l时,根系SOd活性大于下胚轴中的活性;Cd2+胁迫下,四季豆下胚轴和根的丙二醛(MdA)含量增加,且根部含量大于下胚轴的量。Cd2+对矮生四季豆种苗生长发育的影响因Cd2+浓度及幼苗部位的不同而异。In order to explore the biological toxicity of Cd2+more systematically, the effects of Cd2+ on the external and internal physiological and biochemical changes in the process of dwarf beans seed germination and seedling growth were studied with hydroponic culture experiments.The results showed that when the concentration of Cd2+ at low level, the effects of Cd2+ on the seed germination and seedling growth were not significant.Seeds germination were activated at a certain extent when Cd2+ concentration ranged from 0.05mg/L to 0.5 mg/L concentrations.The roots and Hypocotyls of seedling exhibited a significant decrease in growth at higher level of Cd2+ concentrations (5～100mg/L).The activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT)could be enhanced at low Cd2+concentrations but inhibited at higher concentration.The activities of POD, CAT were more inhibited in roots than in Hypocotyls at the same Cd2+ concentrations, while that of SOD was higher in roots than in Hypocotyls when the concentration of Cd2+ was more than 0.5mg/L.The malondialdehyde (MDA) contents were continuously increased with Cadmium exposure in both roots and Hypocotyls.The effects of Cd2+on the dwarf beans’growth were varied with the concentration of Cd2+ and the parts of plants.“2007AA10Z441”项目的资助;“07JC14025”项目的资助;“07DZ12055”项目的资

Pricing Lookback Option of Discrete Arithmetic Averaging Assets′Floating Striking Price in Models with Jumps

在标的资产价格遵循跳跃扩散过程的假设下,运用风险中性定价法和EdgEWOrTH级数逼近及条件期望等相关知识,推导出以离散算术平均资产为浮动执行价的回望买入期权的价格公式.When the underlying asset price follows the jump-diffuse process,we deduce the analyzing pricing formula of the lookback options of the discrete arithmetic averaging assets′floating striking price that utilizes the risk-neutral pricing method,Edgeworth series expansion,and the relevant knowledge of conditional expectation.国家自然科学基金(11071202

Synthesis,Mossbauer Spectra and Magnetic Properties of a Dimeric Spin-crossover Complex

自旋交叉化合物的电子构型双稳性使其在分子传感器、信息存储器件等方面具有可观的应用前景.合成了一个在高温区发生自旋交叉转变的双核化合物并对其进行表; 征.173; K的单晶结构解析显示该化合物的所有${\rm{F}}{{\rm{e}}^{{\rm{II}}}}$离子都处于低自旋态.${\rm{F}}{{\r; m{e}}^{{\rm{II}}}}$离子通过与三氰基甲烷阴离子配体桥连,形成双核结构.常温穆斯堡尔谱显示该化合物含有2个独立的低自旋${\rm; {F}}{{\rm{e}}^{{\rm{II}}}}$组分.变温磁化率测试表明,大约50%的该化合物分子在高温区(286~390; K)发生从低自旋态到高自旋态的转变.该结果表明使用具有较强配体场的桥连配体可有效诱导自旋交叉行为.Spin-crossover materials have attracted considerable interests due to; their potential applications such as the deve-lopment of miniature; molecule-based display devices or data storage elements. We report here; in the synthesis and characterization of a dimeric Fen complex that; shows spin crossover at high temperatures.Single-crystal X-ray; diffraction studies at 173 K revealed that the; ${\rm{F}}{{\rm{e}}^{{\rm{II}}}}$ ions were bridged by tricyanomethanide; groups to form a dimeric structure,and the resulting complex was in a; whole low-spin state. The Mossbauer spectrum at room temperature; indicated that the complex was composed of two low-spin Fen species.; Variable-temperature magnetic susceptibility measurements implied that; about 50% of the complex molecules underwent a low-spin-to-high-spin; conversion in the 286-390 K temperature range.The result indicates that; spin crossover can be induced by strong bridging ligands.国家自然科学基

A study on controllable preparation of nano-hydroxyapatite coatings on Ti substrate by electrochemical deposition

采用电化学沉积法在医用金属钛表面制备钙磷盐涂层,通过XRD、FT-IR和SEM表征,侧重探索电化学沉积技术在温和条件下制备结晶结构优良的纯羟基磷灰石涂层的可控性。通过控制电流密度和反应时间,即研究在恒电量条件下羟基磷灰石涂层的电化学沉积规律性,并获得电化学沉积制备纳米有序结构羟基磷灰石涂层的最佳实验条件,同时对纳米有序结构羟基磷灰石涂层的电化学沉积机理进行讨论。The Ca/P coatings was moderately prepared by electrochemical deposition on Ti substrate in a special experiment condition in constant electric quantity.The prepared coatings was then characterized by XRD,FT-IR and SEM to correlate their chemical composition,structure and morphology with the preparation parameters.The results indicated that the electrochemically prepared Ga/P coating was pure hydroxyapatite with a fine crystallization.The formation rules of the hydroxyapatitie coatings were elucidated in the different experimental conditions.It was demonstrated that it is possible to realize a controllable preparation of nano hydroxyapatitie coatings on Ti substrate by adjusting supplied current and deposition time in the experimental conditions.国家自然科学基金资助项目(20273055);; 教育部博士点基金资助项目(20020384012);; 国家高技术研究发展计划(863计划)资助项目(2003AA302230);; 福建省重大项目资助课题(20031001

The Crystal Growth Behavior of Hydro xyapatite Coating on Titanium Subst rate under Electrochemical Deposition Condit ions

采用恒电流电化学沉积方法从含钙与磷盐水溶液中直接在纯金属钛电极表面沉积纳米羟基磷灰石涂层,运用EDS、SEM、XRD、FTIR等方法对其进行表征.重点考察了一种典型制备条件下钙磷沉积层的形貌、结构及组分随沉积时间的变化,进而探讨相应条件下电化学沉积羟基磷灰石涂层晶体生长过程的基本规律.研究表明电化学沉积法可用于在医用金属表面直接涂覆含钙离子缺陷的纳米羟基磷灰石涂层,典型条件下涂层的生长规律为:(1)沉积过程中羟基磷灰石晶粒以c轴方向沿沉积面法线方向择优生长,且这一趋势延续整个沉积过程;(2)内层晶粒的生长受到外层晶粒生长的抑制,对于同层的晶粒,当晶粒分布密集时,晶粒生长可能发生相互制约;(3)随沉积时间的延长,沉积量增加,而膜层的化学组成基本不发生变化.A nano-hydroxyapatite coating on ti tanium substrate was directly prepared by electrochemical de-position method and was characteriz ed by EDS,SEM,XRD and FTIR.It was observed that under a wide range of deposition conditions calcium-d eficient hydroxyapatite coatings with different topographies can be pr epared.Under a representative preparation condition,i.e.a titanium substrate was used as working electrode with a Pt electrode as counter electrode,the electrolyte was composed of 4.2×10 -4 mol ·L -1 Ca (NO 3 ) 2 ,2.5×10 -4 mol ·L -1 NaH 2 PO 4 and 0.9%NaCl,with a pH adjusted to be6.0,and galvanostatic mode with 1mA·cm -2 cathodic current density was applied at the te mperature of 100℃,a series of hydroxyapatite coatings under different deposition durations(15,30,60,120and 240min)were prepared and characterized to i nvestigate the coating growth behavior.Following laws of c oating growth were observed:(1)preferential growth with the c-axis of the hydroxyapatite crystal perpendicu lar to working surface is always dete cted in the XRD measurements with the peak of (002)crystal face being greatly intensif ied;(2)the growth of grains at inner layer is impeded by the growth of those at outer layer;when g rains are packed closely,competition between the growths of grains at th e same layer takes place;(3)the amount of deposited coating increases with deposition time while the chemical composition almost keeps the same.国家自然科学基金(20273055);; 教育部博士点基金(20020384012);; 国家高技术研究发展规划(2003AA302230)资助项目~

An Electrochemical Etch Technique on the Preparation of High Performance of HA/Ti Compound Biomaterials

电化学沉积法在光滑钛表面上得到的羟基磷灰石涂层存在着不耐载荷,应力作用下结合界面易被破坏的缺陷.本文采用电化学刻蚀技术在钛表面形成微观的粗糙结构.然后用电化学方法在粗糙化的钛表面直接沉积纯的羟基磷灰石,并应用XRD,SEM,FTIR漫反射光谱,电化学交流阻抗及拉伸结合力实验等对复合膜层的化学组成、结构及力学性能进行表征.结果表明,钛表面经粗糙化后可改善羟基磷灰石与钛基体之间的界面状况,显著提高羟基磷灰石涂层与钛基体的结合力.实验表明,电化学沉积可获得纳米尺度均匀致密的纯羟基磷灰石涂层,有望提高植入体的表面生物活性.Electrochemical technique has been developed to prepare HA biomaterial coating on Ti substrate.This technique shows overwhelming advantageous over others.However,the adhesion strength between the HA coating and the substrate produced by the electrochemical deposition method is much lower than that by the plasma spray method.In order to solve this problem,an electrochemical etching technique has been developed by treating Ti in NaBr solution,to form a suitable microstructure on Ti surface.After electrochemical etching there formed a rougher surface with a secondary structure of 1~3 μm porous.The diameter of the titanium surface can be easily controlled by altering the etch condition.After the pretreatment of titanium surface,the electrochemical deposition was conducted to prepare the composite biomaterial of HA/Ti.XRD,SEM,FTIR,electrochemical impedance spectra and mechanical experiment have been used to characterize the prepared HA/Ti biomaterial.It has been indicated that the adhesion strength between the Ti surface and HA coating can be greatly increased on account for the microstructure of Ti surface,and it can be of very high bioactivity due to the excellent structure and pure composition of HA deposited by the electrochemical technique.国家自然科学基金(20273055;;1130 K16002);; 教育部博士点基金(20020384012)资

CORRELATION BETWEEN COMPOSITION of REINFORCING STEEL SURFACE FILM AND STEEL CORROSION BEHAVIOR IN SIMULATED CONCRETE PORE SOLUTIONS

采用XPS分析钢筋经模拟混凝土孔隙液浸泡后表面膜的化学组成,结合线性极化法和动电位扫描阳极极化曲线测试,研究钢筋在模拟混凝土孔隙液中表面膜化学组成与腐蚀电化学行为的关联.结果表明:钢筋在纯模拟液中处于钝化状态.在含Cl和不同PH值的模拟混凝土孔隙液中,随着Cl---浓度的增加和PH值的降低,钢筋的腐蚀电位负移,电流密度增大;钢筋表面钝化膜fE--(2+)的含量增加,fE--(3+)的含量减少.当模拟液中外加Cl---浓度达0.6MOl/l或PH值降至11.31时,钢筋表面不发生钝化,但加入0.24MOl/l nAnO_2缓蚀剂后又可使钢筋钝化从而抑制腐蚀.It is well known that reinforcing steel in concrete can be protected from corrosion by forming a compact passive film on its surface in a concrete pore solution with high alkalinity.The corrosion behavior of the steel is related to its passivation and depassivation.The pH value and the Cl---concentration in a concrete pore solution are of the most important parameters affecting the passivity of reinforcing steel in concrete.In the present work,XPS analysis,linear polarization and potentiodynamic anodic polarization tests were used to study the relationship between the electro-chemical corrosion behavior of reinforcing steel immersed in a simulated concrete pore solution and the chemical composition of the steel surface film.The results showed that with the increase of the Cl---concentration or the decrease of the pH value in the solution,the corrosion potential of the steel shifted negatively and its corrosion current density rose,and the Fe--(2+)content of the steel surface film increased and the Fe--(3+)content decreased.The steel was in an active state in the solution with Cl--- concentration higher than 0.6 mol/L or pH lower than 11.31,and the addition of 0.24 mol/L NaNO_2 to the solution could protect steel from corrosion.国家自然科学基金项目21073151;国家自然科学基金重点项目50731004;国家高技术研究发展计划项目2009AA03Z327资助---