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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Inorganic Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Sol-Gel,Potassium-substituted hydroxyapatite/β-TCP/CPP,Nano-particles
- چکیده:
- چکیده انگلیسی: The new triphasic potassium−substituted hydroxyapatite (KHAP), β−tricalcium phosphate (β−TCP), and calcium pyrophosphate (CPP) proportions using easy sol−gel method were synthesized. The prepared powders was characterized by X–ray diffraction (XRD), Fourier transform infrared (FTIR), Differential thermal behavior (DTA) analysis, Energy Dispersive X–ray Analysis (EDXA), and Brunauer–Emmett–Teller (BET). In addition, the size of nano particle and micro–strain of the synthesized samples using Williamson–Hall (W–H) plots and transmission electron microscopy (TEM) were measured. The (K+Ca)/(P+C) molar ratio in the KHAP samples was around 1.67. Actually, the incorporation of potassium in the calcium deficient apatites was accompanied by the formation of mentioned triphasic mixture ceramics, upon calcination from 400 to 600 °C. However, increasing of the firing temperature to 700 °C resulted in growth of the HAP content as the dominant phase. The XRD peaks of these prepared nano−structures show same pattern with pure HAP phase with hexagonal structure and P63/m space group. Moreover, the evaluated particle size of synthesized samples by W–H and TEM methods are in good agreement as 25–95 nm. Surface area of calcined KHAP samples at 400 to 700 °C were found as 127.83, 48.39, 12.91, and 5.32 m2 g−1, respectively.
- انتشار مقاله: 08-08-1396
- نویسندگان: Mohammad Chahkandi,Behzad Chahkandi
- مشاهده
- جایگاه : پژوهشی
- مجله: Physical Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: DFT,Ab initio calculations,Tripeptide structures,Ramachandran map,conformers
- چکیده:
- چکیده انگلیسی: An ab initio and density functional theory (DFT) study about conformational analysis of tripeptide model HCO−GLY−L−ILE−GLY−NH2 is presented. The tripeptide was scanned about initial, central, and final residues, separately while for every scanning procedure the two other residues had been kept in the β conformation and side chain (SC) dihedral angles were maintained on the gauche− (g‾) state (χ1, χ2 = ‒60). Conformers (L, L, D, D, D), (L, L, D), and (L, L, D, L) were found through scanning of the tripeptide about initial, central, and the last amino acids, respectively. At first, geometries of all conformers were optimized at the HF/6-31G (d) and B3LYP/6-31G (d) levels of theory. In the followings, their thermodynamic properties were obtained with performing of the frequency calculations at the same levels used for optimization. Finally, comparison of the calculated thermodynamic results of the found conformers to the tripeptide minima on Ramachandran map as the standard criteria proposed LLL as the most stable one.
- انتشار مقاله: 06-04-1392
- نویسندگان: Behzad Chahkandi,Mohammad Chahkandi,Bentolhoda Ashrafi
- مشاهده
- جایگاه : پژوهشی
- مجله: Inorganic Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Sol-Gel,Potassium-substituted hydroxyapatite/β-TCP/CPP,Nano-particles
- چکیده:
- چکیده انگلیسی: The new triphasic potassium−substituted hydroxyapatite (KHAP), β−tricalcium phosphate (β−TCP), and calcium pyrophosphate (CPP) proportions using easy sol−gel method were synthesized. The prepared powders was characterized by X–ray diffraction (XRD), Fourier transform infrared (FTIR), Differential thermal behavior (DTA) analysis, Energy Dispersive X–ray Analysis (EDXA), and Brunauer–Emmett–Teller (BET). In addition, the size of nano particle and micro–strain of the synthesized samples using Williamson–Hall (W–H) plots and transmission electron microscopy (TEM) were measured. The (K+Ca)/(P+C) molar ratio in the KHAP samples was around 1.67. Actually, the incorporation of potassium in the calcium deficient apatites was accompanied by the formation of mentioned triphasic mixture ceramics, upon calcination from 400 to 600 °C. However, increasing of the firing temperature to 700 °C resulted in growth of the HAP content as the dominant phase. The XRD peaks of these prepared nano−structures show same pattern with pure HAP phase with hexagonal structure and P63/m space group. Moreover, the evaluated particle size of synthesized samples by W–H and TEM methods are in good agreement as 25–95 nm. Surface area of calcined KHAP samples at 400 to 700 °C were found as 127.83, 48.39, 12.91, and 5.32 m2 g−1, respectively.
- انتشار مقاله: 08-08-1396
- نویسندگان: Mohammad Chahkandi,Behzad Chahkandi
- مشاهده