Hydroxyapatites enriched in silicon – Bioceramic materials for biomedical and pharmaceutical applications

Hydroxyapatite (Ca10(PO4)6(OH)2, abbreviated as HA) plays a crucial role in implantology, dentistry and bone surgery. Due to its considerable similarity to the inorganic fraction of the mineralized tissues (bones, enamel and dentin), it is used as component in many bone substitutes, coatings of metallic implants and dental materials. Biomaterial engineering often takes advantage of HA capacity for partial ion substitution because the incorporation of different ions in the HA structure leads to materials with improved biological or physicochemical properties. The objective of the work is to provide an overview of current knowledge about apatite materials substituted with silicon ions. Although the exact mechanism of action of silicon in the bone formation process has not been fully elucidated, research has shown beneficial effects of this element on bone matrix mineralization as well as on collagen type I synthesis and stabilization. The paper gives an account of the functions of silicon in bone tissue and outlines the present state of research on synthetic HA containing silicate ions (Si-HA). Finally, methods of HA production as well as potential and actual applications of HA materials modified with silicon ions are discussed.     

温度对40Cr钢温挤压成形的摩擦--磨损性能影响

采用温挤压技术对40Cr钢进行成形试验,考察了不同温度下温挤压试样的摩擦-磨损行为.通过扫描电镜、能谱仪和X射线衍射仪分析了40Cr钢磨损后表面形貌、化学元素分布和物相组成,讨论了40Cr钢温挤压的磨损机理.结果表明,在挤压温度为550℃时试样晶粒尺寸细小,残余奥氏体含量较高,硬度最高,其磨损性能为最佳;而当温度为650℃和750℃时,晶粒尺寸较粗大,残余奥氏体含量降低.在5N载荷作用下,挤压温度为550℃时,摩擦因数为0.7667;当挤压温度达到650℃,摩擦因数为0.8587,提高了12.01%,磨损性能降低;750℃时,摩擦因数为0.8764,相比550℃提高了14.31%,磨损性能进一步变差;在550、650和750℃时,磨损形式主要为磨粒磨损.     

一种[011]取向镍基单晶合金的蠕变断裂

研究了[011]取向的镍基单晶高温合金在750~980℃温度范围和200~680 MPa应力下的蠕变断裂特征。在扫描电镜上对各种实验状态下的蠕变断口和纵向剖面进行了详细观察。研究发现：在低温750℃和中温870℃不同初始蠕变应力条件下,枝晶间区亚晶界处不规则γ＇/γ界面是裂纹主要萌生场所,这些已萌生的裂纹在与外加应力轴垂直的(011)面上沿＜110＞和＜100＞两个方向扩展;980℃不同初始应力条件下,裂纹主要在合金中显微疏松孔洞处萌生,沿与外应力轴垂直的方向扩展。观察750℃和870℃不同应力状态蠕变试样的纵向剖面,对亚晶界区不规则γ＇相面积分数的测量和计算表明,用面积分数表征该合金[011]取向在中低温状态下的蠕变损伤程度是可行的。     

Analysis of Pyrolysates for Polysulphoneamide Fiber by Py-GC/MS

Pyrolysis of polysulphoneamide fiber has been investigated using pyrolysis gas chromatography-mass spectroscopy at the different temperatures from 420℃ to 750℃. Its compositions of pyrolysates have been analyzed. At 420℃,pyrolysis of molecular chain could not completdy take place, 12 compounds of pyrolysis have only been identified. When the temperature increases, the compositions of pyrolysate increase sharply. Several compounds, especially sulfur dioxide, benzene, aniline, benzoic acid, 1,4-benzene dicaronitrile, N-phenyl-acetamide, diphenylamine, benzc[g] isoquinoline, N-phenyl-benzamide, hi-（ 4-cyanophenyl ）benzamide, could be formed. The degradation mechanisms which are determined by structure and amount of the thermal decomposition products are described. During pyrolysis, for polysulphoneamide, polymeric chain scissions take place as a successive removal of the monomer units from the polymeric chain. The chain scissions are followed by secondary reactions, which lead to a variety of compounds. Additional reactions can also take place during pyrolysis.     

Pyrolysis of Polytrimethylene Terephthalate （PTT） Fiber by Pyrolysis Gas Chromatography-Mass Spectroscopy

Pyrolysis of polytrimethylene terephthalate (PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of the temperature on its composition of pyrolysates. At 400℃, pyrolysis of molecular chain could occur, only 13 pyrolysates could be identified. The trimethylene moieties bound to the macromolecular core by ester bonds are cleaved at around 400℃. At 550℃ -750℃, pyrolysis of molecular chain could completely take place, 46 pyrolysates could be found. As the temperature increases, the compositions of pyrolysate are distinctly increased. Several compounds, especially benzoic acid, monopropenyl-p-phthalate, 2 - propenyl benzoate, di - 2 - propenyl ester, 1,4 -benzenedicarboxylic acid, benzene, 1, 5 - hexadiene, biphenyl and 1, 3 - propanediol dibenzoate could be formed. The thermal degradation mechanism, which is determined by structure and amount of the thermal decomposition products, are described. During pyrolysis of polytrimethylene terephthalate, polymeric chain scissions take place a peeling reaction as a successive removal of the dimer units from the polymeric chain. The chain scissions are followed by the elimination reaction, linkage action and secondary reactions, which bring about a variety fragment.     

多晶MgB2相形成中纳米尺寸硼粉的作用

原料硼粉在MgB2相形成中的作用已经利用原位高温电阻率(HT-ρT)的测量技术进行了研究.MgB2相形成中的起始转变温度Tonset和相转变完成温度TPF在完成了的热处理过程中已直接确定了.用纳米硼粉和镁粉制备MgB2样品(简称为NanoB-MgB2)时的Tonset和TPF这2个温度值分别是440和 490 ℃,类似于用微米硼粉和纳米镁粉制备MgB2样品(简称为MicroB-MgB2)的情况.这表明MgB2相形成的温度并不特别依赖于硼粉的尺寸.另外,烧结温度的上极限TN是750 ℃,在此温度下NanoB-MgB2样品的超导电性将丧失.此温度远低于用微米硼粉和毫米尺寸的镁粉制备的MgB2样品(简称为DM-MgB2)的TN= 980 ℃.把直接在650 ℃＜T N,烧结的样品与先在750 ℃下烧结,之后又再次重磨和处理后,并于富镁的环境中在650 ℃下再烧结处理的样品相比较,观察到了MgB2的不可逆的晶体结构转变.     

粒化碱性高炉矿渣中原始矿物相的形成研究

研究了粒化碱性高炉矿渣中晶出原始矿物相的类型与矿渣化学成分之间的关系.结果表明：不同化学成分的矿渣当加热温度高于700℃以上时,莫硅镁钙石首先结晶析离,并随温度的升高转化为黄长石.黄长石的结构参数,按其化学成分是在钙铝黄长石和镁黄长石之间变化,黄长石作为原始矿物相在碱性矿渣中比较罕见.     

水热法合成含锌羟基磷灰石

自然骨中的无机组分并不是纯的羟基磷灰石[（Ca10（PO4）6（OH）2,Hydroxyapatite,简称HA],还含有微量镁离子（Mg2＋）、锌离子（Zn2＋）等。为满足临床的需要,常常需要在HA中添加锌元素制成含锌羟基磷灰石（Zn-HA）,其有望成为新一代的骨修复和替换材料。以硝酸钙、磷酸三铵、硝酸锌为原料,在210℃下水热处理8h合成Zn-HA和Ca19Zn2（PO4）14混合粉末。采用X射线衍射（XRD）、电子扫描电镜（SEM）和热重—差热分析（TG-DTA）法对合成粉体的晶相、形貌和热稳定性进行分析。结果表明：在210℃、8h的实验条件下,反应釜的填充度较大时容易合成Zn-HA,但Zn掺量的摩尔分数不宜超过4%;随着Zn掺量和反应釜填充度的增加,HA的结晶度下降;Zn的掺入促使HA易分解,使其热稳定性较差。     

低温固相反应法制备NiFe_2O_4纳米粉及机理研究

采用机械研磨方法制备前驱体,再将前驱体进行煅烧得到NiFe2O4纳米粉.重点研究了煅烧温度对粉体物相和形貌的影响以及固相反应过程与机理.结果表明:煅烧过程中晶粒长大活化能为12.08 k J·mol-1,主要以界面扩散为主;煅烧温度为700℃时粉体团聚严重,颗粒之间存在片状非晶态化合物,结晶度低;750℃煅烧1 h得到的NiFe2O4纳米粉物相单一,粒径分布在35~85 nm之间,温度过高时晶粒明显长大;机械研磨洗涤后前驱体主要由Fe2O3,NiO和NiFe2O4组成,反应产物结晶度低,反应不完全;盐颗粒的存在能抑制晶粒生长,减小产物粒径.     

NaCl掺杂浓度对方钠石结构的影响

文章用水热法合成了含氯方钠石粉末,并讨论了 NaCI的掺杂浓度、晶化时间和晶化温度对方钠石结构的影响。通过X射线衍射（XRD）,扫描电镜（SEM）和热重分析（TG -DTA -DSC）对合成方钠石结构、形貌和热稳定性进行分析。结果表明,NaCI的掺杂量在2％～10％内合成样品产物为单一方钠石结构,当掺杂量达到20％时,合成产物结构发生变化,最佳晶化温度为80℃,晶化时间为6h。扫描电镜图片显示样品颗粒均匀,粒径为01．～02．μm。热重分析表明样品在230℃附近有吸热反应。     

矿物-腐殖酸复合体对菲的吸附研究

摘要:选用高岭土、蒙脱土、针铁矿为代表性矿物，腐殖酸（HA）为代表性有机质，制备了矿物-HA复合体，通过FTIR、XRD、DSC等表征手段分析HA与矿物复合前后的形态结构的变化，并研究不同溶液化学条件下HA与矿物复合前后对菲吸附规律. 结果表明:与矿物复合后HA的玻璃态转变温度Tg由64.6℃变为32.6（高岭土-HA）、51.5（针铁矿-HA）、16.5、77.7℃（蒙脱土-HA），体现了HA的结构及致密程度发生了改变. 矿物-HA复合体对菲吸附的Koc值比未复合的HA减小50%左右，线性程度有所增强. 相对于Ca2+而言，Na+的存更有利于HA及其复合体对菲的吸附. 离子强度对菲在不同矿物-HA复合体上吸附的影响并不完全一致；较低的pH 4有利于菲在各种矿物-有机质复合体上的吸附，此时，蒙脱土-HA复合体对菲的吸附亲和力最大. 研究为阐明HOCs在土壤/沉积物中的迁移转化规律具有重要的意义.     

La_(0.9)Mg_(0.1)Cr_(1-x)M_xO_3钙钛矿型氧化物的制备及催化性能研究

采用溶胶-凝胶法制备一系列钙钛矿复合氧化物La0.9Mg0.1Cr1-xMxO3(M为Fe、Cu和Ni),并考察其催化性能.同时利用扫描电子显微镜和X射线衍射等分析方法,表征催化剂性能与结构之间的关系.实验结果表明:750℃焙烧制得的La0.9Mg0.1Cr0.8Cu0.2O3具有良好的三效催化性能,在该催化剂上C3H6、CO和NO的起燃温度T50较低,分别为229℃、202℃和286℃;完全转化温度T90分别为325℃、247℃和348℃;500℃转化率分别高达91.1%、99.3%和93.9%.La0.9Mg0.1Cr0.8Cu0.2O3具有良好的钙钛矿晶体结构,晶粒为纳米级,热稳定性高,所以催化性能良好.     

SiO2-Al2O3-ZnO-SrO-La2O3系微晶玻璃性能的研究

SiO2-Al2O3-ZnO-SrO-La2O3为基本成分制备了微晶玻璃样品,在750℃下不同时间热处理。用微波微扰法测量其微波介电性能,结合扫描电镜和X射线衍射分析了其晶相。结果表明,随保温时间的延长,样品的主晶相经历了SrZrSi2O7→SrAl2Si2O8→新玻璃相La2ZrTiO7的变化。SrAl2Si2O8相是亚稳过渡相。反应生成的新玻璃相La2ZrTiO7的Q值高达1800,温度系数约为＋500×10^-6／℃。     

组装法制备壳聚糖/羟基磷灰石/海藻酸复合膜及其性能测定

利用壳聚糖和海藻酸能通过正负电荷吸引形成聚电解质膜的特点,采用层层组装的方法制备了壳聚糖/羟基磷灰石/海藻酸复合膜.用电子扫描电镜观察了复合膜的断裂面和膜内羟基磷灰石(HA)的形貌.研究了复合膜的透光率、溶胀率及热稳定性.结果表明复合膜内HA为贝壳状和花瓣状的纳米晶体,复合膜的断裂面为紧密的连续结构.随着组装次数增加,复合膜的溶胀率变化不大,复合膜的分解温度为301℃.这种具有片状纳米HA的复合膜可能成为一种潜在的骨细胞培养支架材料.     

MgB2超导材料的薄膜制备及其超导器件的实现

报道了采用电子束蒸发技术实现MgB₂薄膜制备的实验工作。通过蒸镀B膜和Mg/B多层膜两种前驱体,分别经高温区(～900℃)和中温区(～700℃)退火处理后成功获得了高质量的MgB₂薄膜样品。对样品的超导性能、晶体结构和表面形貌进行了详细的测量和表征,并对两类样品性质上所表现出的差异进行了分析。此外,还报道了在薄膜制备基础上利用微加工技术实现的超导微波谐振器的结果。     

用磷灰石裂变径迹研究西湖凹陷的古地温

对西湖凹陷HY1411井的岩心和岩屑样品中的磷灰石进行了系统的裂变径迹测定 ,并对该井所代表的西湖凹陷地热史进行了分析和模拟。研究结果表明 ,西湖凹陷磷灰石裂变径迹退火带深度为 2 0 0 0～ 390 0m ,相应的古地温为 70～ 12 5℃ ,古地温梯度为 2 .8℃ / (10 0m)。西湖凹陷主要生油岩是下第三系暗色泥页岩 ,其大量生成油气的温度约为 90℃ ,生油门限是 2 80 0m左右。西湖凹陷的磷灰石裂变径迹长度为单峰分布 ,说明此地区自第三纪以来仅经历了一次热事件作用 ,且与该地区大地构造活动一致。这说明此方法是可信的 ,值得进一步推广。     

Closure temperature of (U-Th)/He system in apatite obtained from natural drillhole samples in the Tarim basin and its geological significance

The apatite(U-Th)/He thermochronometry has been used to study the tectono-thermal evolution of mountains and sedimentary basins for over ten years.The closure temperature of helium is important for the apatite(U-Th)/He thermochronometry and has been widely studied by thermal simulation experiments.In this paper,the apatite He closure temperature was studied by establishing the evolutionary pattern between apatite He ages and apatite burial depth based on examined apatite He ages of natural samples obtained from drillholes in the Tarim basin,China.The study showed that the apatite He closure temperature of natural samples in the Tarim basin is approximately 88±5℃,higher than the result(～75℃) obtained from the thermal simulation experiments.The high He closure temperature resulted from high effective uranium concentration,long-term radiation damage accumulation,and sufficient particle radii.This study is a reevaluation of the conventional apatite He closure temperature and has a great significance in studying the uplifting events in the late period of the basin-mountain tectonic evolution,of which the uplifting time and rates can be determined accurately.     

A study on in vitro and in vivo bioactivity of nano hydroxyapatite/polymer biocomposite

When bioactive materials are implanted in vivo, a bone-like apatite layer can be found on their surfaces, which is critical to the establishment of bone-bonding between materials and living tissues. In this study, bone-like apatite formation in vitro and in vivo on surface of nano apatite/polyamide (n-HA/PA66) composite was investigated, and the interface between the implanted composite and surrounding bone tissue of rabbit were also examined. The results revealed that in both simulated body fluids (SBF) and dorsal muscles of rabbit, bone-like apatite could form on the biocomposite surface. When the samples were implanted in cortical bone, they combined directly with the natural bone without fibrous tissue in-between. The results showed that the n-HA/PA66 biocomposite had excellent bioactivity, which might be a good candidate for bone defect replacement.     

水蒸气活化液化木基活性碳纤维孔隙结构表征

 研究了不同活化温度、不同活化时间下,水蒸气活化液化木基活性碳纤维的孔隙结构特性。-196℃氮气吸附脱附等温线用于检测孔隙结构。结果表明,随着活化温度或活化时间的增加,比表面积和烧失率增加,且在较高活化温度时增加率更高。随着活化时间延长,活化温度为750~800℃时总孔容和微孔孔容增加明显,中孔孔容在650~700℃活化初期和750~800℃活化后期均有所发展。各活化温度下,随着活化时间的延长,在微孔范围内孔径分布均有所扩大且趋向多样化。     

不同条件对钙钛矿型BaZrO3储存NOx的影响

采用改进的柠檬酸络合溶胶-凝胶法制备了钙钛矿型BaZrO3催化剂, 考察了焙烧温度, 吸附温度及SO2浓度对BaZrO3样品富氧条件下的NOx储存性能(NSC)的影响; 对其储存的NOx进行了程序升温脱附(TPD-MS)测试, 并用BET比表面测定(SA), X射线衍射(XRD)等方法研究了催化剂的结构及其对性能的影响. 结果表明, 750℃下焙烧的BaZrO3具有相当高的比表面(84.0 m2/g), 而900 ℃下焙烧的BaZrO3样品烧结程度较高, BaZrO3是主要的NOx吸附中心, BaZrO3-750 ℃的NSC高于BaZrO3-900 ℃. BaZrO3样品储存NOx的最佳温度应该在400 ℃左右.