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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Inorganic Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Gas chromatography,Sol-Gel,Transmission electron microscopy,Magnetic nanoparticle,Phthalate esters,Potassium substituted hydroxyapatite,Fourier transform infrared spectrometry,X-ray diffraction
- چکیده:
- چکیده انگلیسی: In this study, we demonstrate the application of newly developed magnetic potassium substituted hydroxyapatite (KHA/Fe3O4) for the extraction of phthalate esters (PE) from water samples. Nanoparticles of KHA were synthesized through an easy alkoxide–based sol–gel technique. The structure of nanocomposite was characterized by X–ray diffraction (XRD), Fourier transform infrared (FTIR) analysis, and energy dispersive X–ray Analysis (EDXA). Moreover, the size of nanoparticle and micro–strain of synthesized KHA and KHA/Fe3O4 using Williamson–Hall (W–H) plots and transmission electron microscopy (TEM) were measured. The hexagonal and cubic structures of synthesized KHA and its nanocomposite having P63/m space group confirmed by XRD pattern. Also, the size of spherical particles of KHA in pure and nanocomposite, and Fe3O4 nanoparticles evaluated by W–H and TEM methods are in good agreement as 60, 65, and 18 nm. The PEs were analyzed by gas chromatography‒flame ionization detector (GC‒FID). Different parameters influencing the extraction efficiency including: sample pH, amount of sorbent, extraction time, desorption conditions, and salt effect, were optimized. The obtained optimal conditions were: sample pH, 7; amount of sorbent, 25 mg; extraction time, 8.0 min; desorption solvent and its volume, 200 μL dichloromethane; and desorption time, 5.0 min. Under optimum conditions, good linearity was achieved for all analytes in the 0.015–100 ng mL−1 concentration range. The limits of detection (at an S/N ratio of 3) are between 0.005 and 0.03 ng mL−1. The recoveries of PEs from spiked real water samples are between 86.3 and 99.2%, with relative standard deviations between 5.3 and 9.3 %.
- انتشار مقاله: 18-02-1398
- نویسندگان: Mohammad Chahkandi,Amirhassan Amiri
- 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
- 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: Gas chromatography,Sol-Gel,Transmission electron microscopy,Magnetic nanoparticle,Phthalate esters,Potassium substituted hydroxyapatite,Fourier transform infrared spectrometry,X-ray diffraction
- چکیده:
- چکیده انگلیسی: In this study, we demonstrate the application of newly developed magnetic potassium substituted hydroxyapatite (KHA/Fe3O4) for the extraction of phthalate esters (PE) from water samples. Nanoparticles of KHA were synthesized through an easy alkoxide–based sol–gel technique. The structure of nanocomposite was characterized by X–ray diffraction (XRD), Fourier transform infrared (FTIR) analysis, and energy dispersive X–ray Analysis (EDXA). Moreover, the size of nanoparticle and micro–strain of synthesized KHA and KHA/Fe3O4 using Williamson–Hall (W–H) plots and transmission electron microscopy (TEM) were measured. The hexagonal and cubic structures of synthesized KHA and its nanocomposite having P63/m space group confirmed by XRD pattern. Also, the size of spherical particles of KHA in pure and nanocomposite, and Fe3O4 nanoparticles evaluated by W–H and TEM methods are in good agreement as 60, 65, and 18 nm. The PEs were analyzed by gas chromatography‒flame ionization detector (GC‒FID). Different parameters influencing the extraction efficiency including: sample pH, amount of sorbent, extraction time, desorption conditions, and salt effect, were optimized. The obtained optimal conditions were: sample pH, 7; amount of sorbent, 25 mg; extraction time, 8.0 min; desorption solvent and its volume, 200 μL dichloromethane; and desorption time, 5.0 min. Under optimum conditions, good linearity was achieved for all analytes in the 0.015–100 ng mL−1 concentration range. The limits of detection (at an S/N ratio of 3) are between 0.005 and 0.03 ng mL−1. The recoveries of PEs from spiked real water samples are between 86.3 and 99.2%, with relative standard deviations between 5.3 and 9.3 %.
- انتشار مقاله: 18-02-1398
- نویسندگان: Mohammad Chahkandi,Amirhassan Amiri
- 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