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Sharghi, Hashem,Paziraee, Zahra,Niknam, Khodabakhsh Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.11
The ring opening of epoxides with elemental iodine and bromine in the presence of three diamine podands 7-9 as new catalysts affords vicinal iodo alcohols and bromo alcohols in high yields. This new procedure occurs regioselectively under neutral and mild conditions in various aprotic solvents even when sensitive functional groups are presented.
Synthesis of barium-doped PVC/Bi2WO6 composites for X-ray radiation shielding
Leila Gholamzadeh,Hamed Sharghi,Mohsen Khajeh Aminian 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1
In this study, composites containing undoped and barium-doped Bi2WO6:Ba2þwere investigated for theirshielding against diagnostic X-ray. At first, Bi2WO6 and barium-doped Bi2WO6 were synthesized withdifferent weight percentages of barium oxide through a hydrothermal process. The as-synthesizednanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM),energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy (RS). After that, some shields weregenerated with undoped and barium-doped Bi2WO6:Ba2þ nanostructure particles incorporated intopolyvinyl chloride (PVC) polymer with different thicknesses and 15% weight of the nanostructure. Finally,the prepared samples were exposed to an X-ray tube at 40, 80, and 120 kV voltages, 10 mAs and, 44.5 cmSID (i.e. the distance from the X-ray beam source to the specimen). Linear and mass attenuation coefficientswere also calculated for different samples. The results indicated that, among the samples, theone with 7.5 mmol barium-doped Bi2WO6 had the most attenuation at the voltage of 40kV, and theattenuation coefficients would increase with an increase in the amount of barium. The samples with 15and 17.5 mmol barium-doped Bi2WO6 had higher attenuation than the others at 80 and 120 kV. Moreover, the half-value layer (HVL), tenth-value layer (TVL) and 0.25 mm lead equivalent thicknesswere calculated for all the samples. The lowest HVL value was for the sample with 7.5 mmol bariumdopedBi2WO6. As the result clearly show, an increment in the barium-doping content leads to adecrease in both HVL and TVL. In every three voltages, 0.25 mm lead equivalent thickness of the barium-doped composites (7.5 mmoland 15 mmol) had less than the other composites. The lowest value of 0.25 mm lead equivalent thicknesswas 7.5 barium-doped in 40 kV voltage and 15 mmol barium-doped in 80 kV and 120 kV voltages. Theseresults were obtained only for 15% weight of the nanostructure.
On the optimum performance-based design of eccentrically braced frames
Reza Karami Mohammadi,Amir Hossein Sharghi 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.16 No.4
The design basis is being shifted from strength to deformation in modern performance-based design codes. This paper presents a practical method for optimization of eccentrically braced steel frames, based on the concept of uniform deformation theory (<i>UDT</i>). This is done by gradually shifting inefficient material from strong parts of the structure to the weak areas until a state of uniform deformation is achieved. In the first part of this paper, <i>UDT</i> is implemented on 3, 5 and 10 story eccentrically braced frames (EBF) subjected to 12 earthquake records representing the design spectrum of ASCE/SEI 7-10. Subsequently, the optimum strength-distribution patterns corresponding to these excitations are determined, and compared with four other loading patterns. Since the optimized frames have uniform distribution of deformation, they undergo less damage in comparison with code-based designed structures while having minimum structural weight. For further investigation, the 10 story EBF is redesigned using four different loading patterns and subjected to 12 earthquake excitations. Then a comparison is made between link rotations of each model and those belonging to the optimized one which revealed that the optimized EBF behaves generally better than those designed by other loading patterns. Finally, efficiency of each loading pattern is evaluated and the best one is determined.
Shamsipur, Mojtaba,Kazemi, Sayed Yahya,Niknam, Khodabaksh,Sharghi, Hashem Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.1
A new PVC-membrane electrode for $Ag^+$ ion based on a thia-substituted macrocyclic diamide has been prepared. The electrode exhibited a Nernstian response for $Ag^+$ over a wide concentration range $(1.7{\times}10^{-6}-1.0{\times}10^{-1}M)$. It has a response time <15 s and can be used for at least 3 months without divergence. The proposed membrane sensor revealed good selectivities for $Ag^+$ over a variety of metal ions and can be used in a pH range 3.0-7.5. It has been used successfully for direct determination of $Ag^+$ in different real samples and, as an indicator electrode, in the titration of silver ion.
Farhadi, Khalil,Shaikhlouei, Hossain,Maleki, Ramin,Sharghi, Hashem,Shamsipur, Mojtaba Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.11
A new solvent polymeric membrane sensor based on tetra(p-chlorophenyl)porphyrinato manganese (III) acetate is described which demonstrates excellent selectivity toward the triiodide ion. The electrode has a linear dynamic range between 1.0 ${\times}$ $10^{-2}$ M and 7.0 ${\times}$$10^{-6}$M with a Nernstian slope of $-59.6{\pm}1$ mV per decade and a detection limit of 5.0 ${\times}$$10^{-6}$M. The proposed sensor revealed good selectivities for triiodide over a wide variety of other anions and could be used in a pH range 2-9. The electrode can be used for at least two months without any considerable divergence in potential. It was applied as indicator electrode in potentiometric titration of the triiodide and As(III) ions.
Theoretical Studies of Hydrogen Bond Interactions in 4-Substituted Benzoic Acids Dimers
Beni, Alireza Salimi,Chermahini, Alireza Najafi,Sharghi, Hashem Korean Chemical Society 2011 대한화학회지 Vol.55 No.3
벤조산 유도체($NH_2$, OH, H, F, Cl, CN, NO, $NO_2$) 의 두 형태를 6-311++G(d,p) 바탕 집합을 이용하여 MP2, DFT 및 HF 수준으로 연구하였으며, cis이성 질체가 더 안정하였다. 벤조산의 수소 결합 형성은 안정화 에너지를 이용하여 추산하였으며, 이합체에 대한 수소결합 에너지 계산치는 고리에서 협동 상호작용이 일어남을 보여주었다. 페닐 고리로 전자를 밀어내는 그룹(ERG)은 더 안정한 수소 결합이 형성하였다. 이합체에서 O-H 결합의 적색이동은 -565.3에서 $-589.3\;cm^{-1}$ 범위였으며, 상호 작용의 특성은 NBO 분석을 이용하여 연구하였다. Two conformations of benzoic acid derivatives ($NH_2$, OH, H, F, Cl, CN, NO, $NO_2$) have been investigated at MP2, DFT and HF level using the 6-311++G(d,p) basis set. It was found that the cis isomers are more stable. Hydrogen bonding formation of benzoic acids has been estimated from stabilization energies. The calculated hydrogen-bonding energies of dimers showed a cooperative interaction in the cyclic ones. It was found that an electron-releasing group (ERG) into the phenyl rings resulted in the formation of more stable hydrogen bonding. Red shift of O-H bond was found from -565.3 to -589.3 for dimers. The natural bond orbital (NBO) analysis was applied to characterize nature of the interaction.
Shamsipur, Mojtaba,Saeidi, Mahboubeh,Yari, Abdullah,Yaganeh-Faal, Ali,Mashhadizadeh, Mohammad Hossein,Azimi, Gholamhasan,Naeimi, Hossein,Sharghi, Hashem Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.5
A new PVC membrane electrode for $UO_2^{2+}$ ion based on 2,2'-[1,2-ethanediyl bis (nitriloethylidene)]bis(1-naphthalene) as a suitable ionophore was prepared. The electrode exhibites a Nernstian response for $UO_2^{2+}$ ion over a wide concentration range ($1.0{\times}10^{-1}-1.0{\times}10^{-7}$M) with a slope of 28.5 ${\pm}$ 0.8 mV/decade. The limit of detection is $7.0{\times}10^{-8}$M. The electrode has a response time of < 20 s and a useful working pH range of 3-4. The proposed membrane sensor shows good discriminating abilities towards $UO_2^{2+}$ ion with regard to several alkali, alkaline earth transition and heavy metal ions. It was successfully used to the recovery of uranyl ion from, tap water and, as an indicator electrode, in potentiometric titration of $UO_2^{2+}$ ion with Piroxycam.