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61.
《Composite Interfaces》2013,20(2):151-165
This study compared bony fusion in autologous bone grafting with HA/ZrO2 graded composite in terms of mineral depositions, histological characteristics, and biomechanical properties of bonding interface. Twenty-four beagle dogs were established four places of bone defect in two adjacent lumbar vertebral bodies (L4 and L5) and were successively implanted with HA/ZrO2 graded composite (group A), HA/ZrO2 unilayer composite (group B), pure ZrO2 (group C), and pure HA (group D). After operation, lumbar vertebral specimens were respectively harvested per time at week 6, 12, and 16. Then, the bony fusion interface was evaluated by fluorescence microscope and computer image analysis system to measure mineral apposition rates (MAR). Histological analysis of specimen was used to determine bone bonding rates (BBR) and possible foreign body reactions associated with each groups. And interface bonding force between implant and autogenous bone was quantified with biomechanical push-out test. Compared with other groups, group A led to significantly higher MAR from week 6 to 12 (p < 0.05). Histologically, new bony tissue and hyaline cartilage were seen around the HA/ZrO2 graded composite, accompanied by mild chronic inflammation. And the BBR of HA/ZrO2 graded composite were the highest (p < 0.05), while reaching (90.3 ± 3.8) % at week 16. Moreover, the biomechanical push-out tests revealed that the maximum interface shear strength of group A was respectively (2.64 ± 0.16) MPa, (2.95 ± 0.19) MPa, and (3.45 ± 0.23) MPa at week 6, 12, and 16, which all possessed significantly statistical differences with other three groups (p < 0.05). 相似文献
62.
Sonia Stita Marta Galera Martínez Huynh Pham Xuan Ange Nzihou Patrick Sharrock 《Composite Interfaces》2013,20(6):503-515
With the expansion of human activities, there are more and more living areas adjacent to industrial and/or agricultural activities such as chemical processes, petroleum processes, paint finishing, food processing, livestock farming, composting plants etc. Bad odor is part of several nuisances caused by industrial and/or agricultural activities. Hydrogen sulfide (H2S) is a typical odorous molecule which causes foul odor at very low concentration. This molecule is formed in different industrial installations, in particular in coal combustion, and petrochemical refinery. The separation and/or transformation of H2S from gas phase to odorless products are important processes for sustainable development. In this paper, we communicate the preparation of new sorbents for the sorption of H2S from a synthetic gas effluent. These sorbents consist in an inorganic phase (hydroxyapatite) as host particles, and well-dispersed particles of a metal oxide as guest particles which are the active phase for the removal of H2S. At room conditions, iron, lead, and zinc doped calcium phosphates were found to be effective for the removal of H2S. The performance of the sorbents depends on preparation method and the nature of active phases. This opens new prospects for the treatment of H2S from gas phase. 相似文献
63.
Li Wenfang South China University of Technology Guangzhou R. R. ChinaDu Shanyi Harbin Institute of Technology Harbin 《Acta Mechanica Solida Sinica》1995,8(1):75-83
The modified equivalent inclusion theory by the authors and the internalvariable theory are employed to investigate the evolution of the microcracks in whiskertoughening ceramics and the influence of the microcracks on the mechanical propertiesof the material. The effect of residual thermostrain, whisker content and aspect ratio isconsidered. The modulus, initial nonlinear load, strength and nonlinear constitutiverelation are calculated and some important conclusions are given. 相似文献
64.
65.
Nemoto Rei Wang Li Ikoma Toshiyuki Tanaka Junzo Senna Mamoru 《Journal of nanoparticle research》2004,6(2):259-265
Hydroxyapatite (HAp) nanocrystals were prepared at room temperature by a coprecipitation method from Ca(OH)2 and H3PO4, in the presence of chemically disintegrated silk fibroin (SF). Adsorbed amounts of cations on SF and crystallinity of HAp in the composite were increased by the chemical disintegration of SF higher order structure. Preferential alignment of c-axis of HAp crystallites along the longitudinal direction of ca. 150nm SF fibril was observed. These changes due to disintegration of SF were discussed in terms of the chemical interaction between HAp and SF. The resulted composite with preferential alignment of HAp nanocrystals is a good candidate as a starting material for bone substitutes. 相似文献
66.
67.
Lin-Li Xu Xiu-Ju Zhang Lin-Hua Zhu Xiao-Nan Lian Kai Xu Ming-Cai Chen 《Journal of Macromolecular Science: Physics》2013,52(1):89-99
Pimelic acid (PA) was used to modify the surface of magnesium sulfate whiskers (M-HOS). The treated M-HOS and its effects as a function of concentration on the crystallization and morphology of isotactic polypropylene (iPP) were investigated. Scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), thermogravimetic analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) revealed that PA reacted with M-HOS and formed magnesium pimelate on the surface after the reaction. The results of differential scanning calorimetry (DSC) and polarized light microscopy (PLM) showed that the treated M-HOS had the ability to induce β-spherulites, increase the crystallization temperature and decrease the size of spherulites in iPP. It was the most effective to form β-spherulites when the content of PA treated M-HOS was 5 wt%. 相似文献
68.
High-density polyethylene (HDPE) nanocomposites reinforced with hydroxyapatite nanorods (nHA) were fabricated by means of extrusion and injection molding. The thermal, mechanical, and dry sliding wear properties of HDPE-based nanocomposites filled with nHA loadings up to 20 wt% were investigated. The results of mechanical property characterization showed that nHA additions improved the hardness, elastic modulus, and yield strength of HDPE at the expense of its tensile ductility and impact strength. Thermogravimetric analysis and heat deflection temperature measurements revealed that nHA fillers are very effective to enhance the thermal stability of HDPE. The wear behavior of HDPE/nHA nanocomposites was studied using a pin-on-disk tribometer. nHA fillers of a large aspect ratio improved the wear resistance of HDPE substantially because of their load-bearing effect and the formation of a continuous transfer film on the steel counterface. 相似文献
69.
Modulus–porosity relationships are critical for engineered bone tissue scaffold materials such as hydroxyapatite (HA), where porosity is essential to biological function. Resonant ultrasound spectroscopy (RUS) measurements revealed that the Young's modulus, E, and shear modulus, G, of both alumina and HA decrease monotonically with increasing volume fraction porosity, P, for 0.06 < P < 0.39 (alumina) and 0.05 < P < 0.51 (HA). Although the elastic moduli of porous materials have been measured by a number of different ultrasonic resonance techniques (of which the RUS technique is one example) and over the last decade the elastic moduli of many solids have been measured by the RUS technique, this study is the first systematic RUS study of porous materials. Comparison of E versus P data for alumina (which has been studied extensively) with literature data from several measurement techniques indicates the RUS technique is effective for modulus–porosity measurements. Another key result is that although the HA specimens included in this study have a unimodal pore size distribution, the details of the decrease in E and G with increasing P agree well with literature data for HA with both unimodal and bimodal pore size distributions. In addition, Poisson's ratio exhibits a local minimum in the porosity range of 0.2 < P < 0.25 for both HA and alumina, which may be related to the pore morphology evolution during sintering. 相似文献
70.
利用酸水解稻壳中的半纤维素制备木糖, 并将糖渣经过炭化后分离出碳和硅, 碳采用稀碱溶液活化改性制备电容炭, 硅采用水热法合成了硅酸钙晶须, 从而使稻壳所有组分得到充分利用. 采用循环伏安(CV)和恒流充放电(GCD)研究了电容炭的电化学性能. 通过X射线衍射(XRD)和扫描电子显微镜(SEM)对所得硅酸钙晶须的结构和形貌进行了表征. 实验结果表明, 稻壳酸水解的最优条件为硫酸浓度7%(质量分数)、 固液比(g/mL)为1:8、 反应时间为2.0 h, 在该条件下, 一次水解、 二次水解和三次水解的木糖收率(Y1/Y2/Y3)和浓度(质量分数, C1/C2/C3)都能达到最大值, Y1=98.5%, C1=3.6%; Y2=85.4%, C2=6.3%; Y3=76.6%, C3=9.0%. 采用15 mL 8%(质量分数) NaOH稀碱溶液活化改性制得的电容炭(AC/15)比电容值为77.32 F/g, 而且具有较好的倍率性和循环稳定性; 硅酸钙晶须为扫帚状针钠钙石晶须. 相似文献