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Characterization of mechanothermal-synthesized hydroxyapatite-magnesium titanate composite nanopowders

Journal of Advanced Ceramics 2013年第1期2卷 63-70页

作者： abbas fahami Bahman NASIRI-TABRIZI Materials Engineering Department Najafabad BranchIslamic Azad UniversityNajafabadIsfahanIran

Hydroxyapatite-magnesium titanate composite nanopowders have been developed using a mechanothermal *** treatment of the milled powders at 700℃resulted in the formation of HAp/MgTiO_(3)-MgO nanocomposite.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and energy dispersive X-ray spectroscopy(EDX)techniques were utilized to characterize the synthesized *** results revealed that the dominant phases after mechanical activation were hydroxyapatite,anatase(TiO_(2))and periclase(MgO);while after thermal annealing process at 700℃,hydroxyapatite along with geikielite(MgTiO_(3))and periclase(MgO)were the major *** on the XRD analysis,the evaluation of structural features of the samples indicated that the average crystallite sizes of hydroxyapatite after 10 h of milling and subsequent thermal treatment at 700℃were about 21 nm and 34 nm,*** observations illustrated that the synthesized powders contained large agglomerates which consisted of significantly finer particles with spheroidal *** is concluded that the mechanothermal method can be used to produce hydroxyapatite-based nanocomposite with appropriate structural and morphological features.

关键词： HAp/MgTiO_(3)-MgO nanocomposite characterization methods mechanothermal

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Structural characterization and strengthening mechanism of forsterite nanostructured scaffolds synthesized by multistep sintering method

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Journal of Materials Science & Technology 2018年第12期34卷 2263-2270页

作者： Fariborz Tavangarian abbas fahami Guoqiang Li Mohammadhassan Kazemi Anoosha Forghani Mechanical Engineering Program School of ScienceEngineering and TechnologyPennsylvania State University Department of Mechanical Engineering Texas A&M University Department of Mechanical and industrial Engineering Louisiana State University Department of Mechanical and Aerospace Engineering University at Buffalo Department of Biomedical Engineering Millennium Science ComplexPennsylvania State UniversityUniversity Park

In this study, highly porous forsterite scaffolds with interconnected porosities were synthesized using multi-step sintering(MSS) method. The starting powder was nanosized forsterite, which was synthesized from talc and magnesium carbonate powders. The phase composition, average particle size and morphology of the produced forsterite powder were characterized by X-ray diffraction technique(XRD) and transition electron microscopy(TEM). Forsterite scaffolds were produced by foamy method using polymeric sponges. MSS process including three steps was used to efficiently sinter the forsterite nanopowders without destroying the initial porous structure of polymeric sponges. The results showed that MSS technique is an efficient and appropriate procedure to produce highly porous forsterite scaffolds with pore size in the range of 100-300 μm. The compressive strength, compressive modulus and porosity of C12 specimen(sintered at 1650℃ for 1 h with subsequent annealing at 1000℃ for 1000 min) was 1.88 MPa, 29.2 MPa, and 72.4%, respectively, which is very close to that of cancellous bone. The approach studied in this research can be developed for other nanostructure ceramics to produce highly porous scaffolds with interconnected porosities for load bearing applications.

关键词： Forsterite Multi-step sintering Scaffolds Porosity

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Structural insights of mechanically induced aluminum-doped hydroxyapatite nanoparticles by Rietveld refinement

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Chinese Journal of Chemical Engineering 2017年第2期25卷 238-247页

作者： abbas fahami Bahman Nasiri-Tabrizi Gary W. Beall Wan Jefrey Basirun Materials Science Engineering and Commercialization Program Texas State University San Marcos 78666 TX USA Advanced Materials Research Center Materials Engineering Department Najafabad Branch Islamic Azad University Najafabad lsfahan lran Department of Chemistry and Biochemistry Texas State University San Marcos 78666 TX USA Physics Department Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia Department of Chemistry Faculty of Science University of Malaya150603 Kuala Lumpur Malaysia

Aluminum doped hydroxyapatite(HA:Al^(3+)) nanopowders were successfully prepared via a simple and efficient one-pot mechanochemical route. The effects of dopant loading on phase compositions and structural features were assessed by Rietveld analysis. The XRD-Rietveld refinement revealed the stabilization of HA in hexagonal structure for all the samples. The sharpness and intensity of the apatite-derived XRD peaks decreased as the dopant content increased to 10% due to the increase in lattice imperfections and mechanically induced amorphization. The incorporation of Al3+into the HA lattice decreased the unit cell parameters. From the FTIR measurements, the representing bands of apatite were identified in all cases. The mechanosynthesized nanopowders consisted of nanospheroids with an average size of 44 ± 20 nm and therefore are promising for bone tissue regeneration.

关键词：羟基磷灰石纳米粒子 Rietveld精修机械化学合成铝掺杂诱导铝结构细化红外光谱测量

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Structural Characterization of Nanocrystalline Ni(50-x)Ti50Cux(X = 5, 9 wt%) Alloys Produced by Mechanical Alloying

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Advances in Nanoparticles 2013年第2期2卷 71-77页

作者： Bahman Nasiri-Tabrizi abbas fahami Materials Engineering Department Najafabad Branch Islamic Azad University Isfahan Iran

Nanocrystalline Ni(50-x)Ti50Cux(X = 5, 9 wt%) alloys were successfully produced by mechanical alloying. Mechanical activation was performed at different milling times under a high purity argon (99.998 vol%) atmosphere. Phase analysis and structural features of the samples were examined by X-ray diffraction (XRD). Results revealed that NiTiCu (B2) phase was achieved after 600 min of milling. The formation of this phase was mostly related to the critical factors in determining the site replacement of elements in Ni-Ti-Cu ternary system. After 600 min of milling, the average crystallite size and lattice strain of the samples were about 5 - 10 nm and 1.057% - 1.967%, respectively. Evaluation of the full width at half maximum (FWHM) values for all the samples indicated the occurrence of anisotropic line broadening. The determined amounts of crystallinity revealed that the fraction of crystalline phase decreased with increasing weight percentage of copper up to 9% and reached a minimum value after 600 min of milling. The lattice parameters and the unit cell volume of the milled samples were always larger than the standard values. In addition, lattice parameter deviation influenced by the weight percentage of copper. Based on the obtained data, mechanical alloying process can be used for production of nanocrystalline NiTiCu alloys with different structural features.

关键词： Nanocrystalline Alloy Mechanical Alloying Phase Analysis Structural Features

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comparison between tocotrienol and omeprazole on gastric growth factors in stress-exposed rats

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World Journal of Gastroenterology 2017年第32期23卷 5887-5894页

作者： Mohd fahami Nur Azlina Hj Mohd Saad Qodriyah Kien Hui Chua Yusof Kamisah Department of Pharmacology Faculty of MedicineUniversiti Kebangsaan Malaysia Department of Physiology Faculty of MedicineUniversiti Kebangsaan Malaysia

AIM To investigate and compare the effects of tocotrienol and omeprazole on gastric growth factors in rats exposed to water-immersion restraint stress(WIRS).METHODS Twenty-eight male Wistar rats were randomly assigned to four groups of seven rats. The two control groups were administered vitamin-free palm oil(vehicle) and the two treatment groups were given omeprazole(20 mg/kg) or tocotrienol(60 mg/kg) by oral gavage. After 28 d of treatment, rats from one control group and both treated groups were subjected to WIRS one time for 3.5 h. Gastric lesions were measured and gastric tissues were obtained to measure vascular endothelial growth factor(VEGF), epidermal growth factor(EGF), basic fibroblast growth factor(b FGF), and transforming growth factor-alpha(TGF-α) m RNA expression. RESULTS Rats exposed to WIRS for 3.5 h demonstrated the presence of considerable ulcers in the form of gastric erosion. The lesion index in the stressed control(S) group was increased(P < 0.001) compared to the tocotrienol treated and omeprazole treated groups. Stress led to a decrease in gastric VEGF(P < 0.001), b FGF(P < 0.001) and TGF-α(P < 0.001) m RNA levels and caused an increase in EGF m RNA(P < 0.001) that was statistically significant compared to the nonstressed control group. Although both treatment agents exerted similar ulcer reducing ability, only treatment with tocotrienol led to increased expression of VEGF(P = 0.008), b FGF(P = 0.001) and TGF-α(P = 0.002) m *** Tocotrienol provides gastroprotective effects in WIRSinduced ulcers. Compared to omeprazole, tocotrienol exerts a similar protective effect, albeit through multiple mechanisms of protection, particularly through up-regulation of growth factors that assist in repair of gastric tissue injuries.

关键词： Tocotrienol Omeprazole 抑制压力胃的溃疡生长因素

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