在湿CO2气氛中热处理生成碳酸羟基磷灰石的探讨

将湿化学法合成的不同钙磷摩尔比的粉体,经1 500℃煅烧后,在含水蒸气的CO2中热处理,制备了碳酸羟基磷灰石.应用X射线衍射、红外光谱、差热和热重分析研究了不同热处理温度和不同钙磷摩尔比下产物的化学结构和相组成,讨论了热处理温度和原料钙磷摩尔比对样品相组成的影响.结果表明：所合成的碳酸羟基磷灰石,碳酸根能够进入晶格.热处理温度为800℃时,晶相中有碳酸钙存在,当原料钙磷摩尔比为1.45时,在823～1 000 ℃下热处理结晶相为碳酸羟基磷灰石.当钙磷摩尔比低于或者高于1.45时,存在磷酸三钙、氧化钙、碳酸钙等其它晶相.     

生物活性梯度涂层中羟基磷灰石的相转变与结构稳定性

重点研究了生物活性梯度涂层中羟基磷灰石高温结构稳定性。探讨了羟基磷灰石在喷涂和热处理过程中的相变化,对比研究了不同热处理条件对羟基磷灰石晶体稳定性和羟基恢复的影响。发现经等离子喷涂后的生物活性梯度涂层中的羟基磷灰石结晶程度明显降低,并出现β－ＴＣＰ杂相。羟基磷灰石晶体中的羟基已完全分解脱落。适当条件的热处理可使喷涂涂层中的磷酸三钙转变为羟基磷灰石,晶体中的羟基可大部分恢复,其中大气热处理比真空热处     

固相离子交换法制备碳酸羟基磷灰石涂层的研究

通过涂覆-烧结法在氧化铝(Al2O3)基体上制备羟基磷灰石(HA)/氟羟基磷灰石(FHA)双层涂层,然后采用固相离子交换法在湿CO2气氛中对HA表层进行碳酸化处理。XRD、FTIR和SEM测试结果表明:FHA中间层能有效地抑制HA与Al2O3的反应,湿CO2气氛中的湿气有利于分解相的恢复,而碳酸根能进入到表面涂层结构内部,形成A型替代为主的碳酸羟基磷灰石(CHA)。所获得的双层涂层具有多孔粗糙的表面,但与Al2O3基体结合紧密。     

TZP增韧HA复合材料的微观结构

用透射电子显微镜对四方氧化锆多晶（ZTP）增韧羟基磷灰石（HA）复合材料的微观相结构进行了观察与分析。结果表明,材料的相组成中,既有HA晶体,还有HA晶体在高温、高压成型过程中发生分解反应产生的磷酸三钙（Ca3(PO4)2晶体和磷酸二钙（Ca2P2O7)晶体;同时,样品中还观察到了三种晶形的氧化锆（ZrO2)：即立方（ZrO2)、四方ZrO2和单斜ZrO2,说明材料内部发生了t-ZrO2（高温型）→m-ZrO2（低温型）的马氏体相变。除此以外,还出现了CaZrO3相,CaZrO3相的形成是HA晶体分解出的CaO与ZrO2相互反应的结果。     

氧化铝基体上羟基磷灰石/氟羟基磷灰石双层涂层的制备及性能

通过涂覆-烧结法在氧化铝(Al_2O_3)表面制得羟基磷灰石(HA)/氟羟基磷灰石(FHA)双层涂层,HA和FHA重复沉积在氧化铝基体上形成均匀涂层,然后在1300 ℃进行热处理.在此过程中,如果没有FHA中间层,HA会和Al_2O_3发生严重的反应,形成磷酸三钙和钙铝化合物.SEM、XRD及粘接拉伸试验表明:FHA中间层能有效地抑制HA与Al_2O_3的反应,所获得的双层涂层具有多孔粗糙的表面,但与Al_2O_3基体结合紧密.涂层经1300 ℃热处理后,其结合强度约为30 MPa.     

磷酸钙生物陶瓷新工艺

近来，一种高强磷酸钙生物陶瓷生产新工艺问世海外。该工艺的问世有效消除了强度与相对密度（生物适应性）之间的技术冲突，为医学应用提供强度高、生物适应性好的磷酸钙生物陶瓷。据介绍，该工艺是将平均粒径为3～30μm的磷酸钙化合物如羟基磷灰石、氟磷灰石、碳酸磷灰石等磷灰石类、磷酸二钙、磷酸三钙或磷酸四钙混合、成型，送入大气炉中于1050～1250℃下预烧一定时间，     

针状缺钙羟基磷灰石涂层的烧结特征及磷酸氢钙相的影响

研究了Ｔｉ６Ａｌ４Ｖ表面针状缺钙羟基磷灰石涂层在４５０－９８０℃空气中烧结后的相组成和显微主磷酸氢钙相的影响,分析了缺钙羟基磷灰石的高温分解行为。烧结过程不仅使Ｔｉ６Ａｌ４Ｖ表面形成致密的ＴｉＯ２保护膜,而且获得了对骨组织生长 有利的 式磷灰石＋β－磷酸三钙双相涂层结构。由此使涂层／基体系统的生物特性和力学性能同时得到改善。     

羟基磷灰石-玻璃复合陶瓷的微波烧结

采用沉淀法合成羟基磷灰石粉体,将R2OAl2O3B2O3SiO3体系玻璃粉按一定的比例与HAP粉混合,采用等静压成型和干压法成型2种成型方法对羟基磷灰石玻璃复合粉体成型,分别在1150℃、1200℃、1250℃下微波烧结。利用XRD、IR和SEM等手段对烧结过程中的相变和陶瓷显微结构进行研究,结果表明随着烧结温度的升高,羟基磷灰石玻璃复合陶瓷的结构逐渐致密;烧结温度低于1200℃时主晶相没有发生明显变化,当烧结温度达到1250℃时等静压成型的样品中HAP发生了明显的分解;等静压成型的羟基磷灰石—玻璃复合陶瓷的致密度优于普通干压法成型的陶瓷。     

相组成对TiO_2薄膜生物活性的影响(英文)

以钛酸正丁酯(Cl6H36TiO4)为原料,采用溶胶-凝胶法制备了TiO2薄膜。TiO2薄膜分别在300,400,500,600,800℃下于空气中热处理2h。将热处理前后的TiO2薄膜浸泡于模拟体液(simulated body fluids,SBF)中,考察其表面诱导类骨磷灰石形成的能力。利用X射线衍射、扫描电子显微镜、能谱仪、Fourier变换红外光谱等测试手段表征TiO2薄膜和磷灰石的微观结构。结果表明:原始和经300℃热处理的TiO2薄膜为无定形结构;随着煅烧温度的升高,TiO2由无定形结构向锐钛矿相转变;温度升高至800℃后,锐钛矿相完全转化为金红石相。TiO2薄膜经SBF浸泡7d后,经400,500,600,800℃热处理的TiO2薄膜表面生成含有碳酸根的羟基磷灰石,且其Ca与P的摩尔比为1.52,接近人体骨骼的钙磷比(1.67)。而原始和经300℃热处理的TiO2薄膜无此现象发生,这说明TiO2薄膜的晶型对其生物活性具有重要影响,锐钛矿和金红石相TiO2薄膜均具有诱导磷灰石生成的能力。     

初始碳酸根含量和热处理对碳酸羟基磷灰石制备和性能的影响

以湿化学法制备了不同碳酸根含量的碳酸羟基磷灰石(carbonated hydroxyapatite,CHA).研究了热处理温度和气氛对这些CHA的烧结、热稳定性和碳酸根替代的影响.通过X射线衍射、Fourier变换红外光谱及热分析等多种测试手段表征了CHA粉体的特性.结果表明:CHA坯体的烧结温度和粉体的热稳定性与初始的碳酸根含量有关,含量越高,烧结温度越低,热稳定性越差.热处理过程中,CHA中碳酸根的替代量随热处理温度的升高而减少,并在热处理过程中A位的碳酸根较B位的碳酸根在更低的温度下失去.湿二氧化碳气氛能促进CHA的烧结,减少碳酸根的损失,提高热稳定性,有利于生成以B型替代为主的CHA.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.