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51.
Sima Ahmadi Mohammad Taghi Hamed Mosavian Somayeh Heydari 《Journal of the Iranian Chemical Society》2018,15(11):2605-2614
A rapid and simple approach for the preconcentration and determination of catechin from pistachio green hull samples has been proposed by surfactant-assisted dispersive liquid–liquid microextraction followed by UV–Vis spectrophotometry (SADLLME/UV–Vis). This method involved the formation of a catechin complex with cetylpyridinium chloride (CPC) as cationic surfactant, and subsequently, DLLME was applied to extract the catechin–CPC complex into chloroform. Different parameters affected the extraction efficiency were optimized by central composite design (CCD) and response surface methodology (RSM). In optimum condition, the calibration curve was linear in the range of 0.4–5 µg mL??1 of catechin with correlation coefficient of 0.9982. The relative standard deviation based on five replicated analyses of 1 µg mL??1 catechin was 1.85%. The proposed method was successfully applied for preconcentration and determination of trace amounts of catechin in pistachio hull samples. 相似文献
52.
Saeed Rayati Saeed Zakavi Somayeh H. Motlagh Vahid Noroozi Maryam Razmjoo Andrzej Wojtczak Anna Kozakiewicz 《Polyhedron》2008
X-ray crystallographic studies have shown that the free base β-tetra-brominated meso-tetraphenylporphyrin (H2TPPBr4) has a slightly ruffled structure with the dihedral angles of 70.1–79.2° between the phenyl groups and the porphyrin mean plane. The N(pyrrole)–N(pyrrolenine) distance is very similar to that of the standard planar porphyrins. The decreased N–H bond length of H2TPPBr4 with respect to that of meso-tetraphenylporphyrin (H2TPP) seems to be due to the weaker intramolecular hydrogen bond of the former relative to the latter caused by the electron-withdrawing effects of the β-bromine substituents. The large red shifts of the Soret and Q(0,0) bands of H2TPPBr4 in comparison with those of H2TPP, in spite of the nearly planar porphyrin core of the compound, also may be explained on the basis of the electron-withdrawing effects of the bromine atoms. Oxidation of styrene, the para-substituted derivatives and cyclooctene with tetrabutylammonium oxone in the presence of catalytic amounts of β-tetra-brominated meso-tetraphenylporphyrinatomanganese(III) acetate immediately gives the epoxide as the sole product. Terminal double bonds and unconjugated ones are less reactive than the conjugated double bonds and show lower selectivities. Catalytic activity of the electron-deficient Mn(H2TPPBr4)OAc dramatically depends on the Co-catalytic activity of the nitrogen donors as the axial base. The best axial bases are the nitrogenous donors with mixed σ- and π-donor ability to the metal centre. 相似文献
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54.
Mohammad Saeid Hosseini Somayeh Khorashahi Navid Hosseini 《Journal of fluorescence》2016,26(3):867-874
The CdSe quantum dots (QDs) capped with 2-mercaptonicotinic acid (H2MN) were prepared through a controllable process at 80 °C. The prepared QDs were characterized by XRD, TEM, IR, UV–Vis and fluorescence (FL) techniques. It was found that the QDs were nearly mono-disperse with the diameters in the range of 8–10 nm. These QDs are capable to exhibit strong FL even in concentrated acidic media. They exhibit an enhanced fluorescence in the presence of Cr(VI), which was used for the determination of Cr(VI) in water samples. The linear range was found to be 1?×?10?7–6.0?×?10?6 M with the RSD and DL of 0.92 % and 5?×?10?8 M, respectively. Except that Ca2+ and Fe3+ which can be eliminated through a simple precipitation process, the other co-existent ions present in natural water were not interfered. The recoveries obtained for the added amounts of Cr(VI) were in the range of 96.9–103.2 %, which denote on application of the method, satisfactorily. 相似文献
55.
Ali Reza Fakhari Davood Nematollahi Somayeh Makarem Abdolali Alizadeh 《Tetrahedron》2007,63(18):3894-3898
Electrochemical oxidation of catechols (1a-c) has been studied in the presence of methyl acetoacetate (2a) and ethyl acetoacetate (2b) as nucleophiles in aqueous solution using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinones derived from catechols (1a-c) participate in Michael addition reactions with 2a and 2b to form the corresponding benzofuran derivatives (3a-f). The electrochemical synthesis of 3a-f has been successfully performed in an undivided cell in good yield and purity. The oxidation mechanism was deduced from voltammetric data and by coulometry at controlled potential. The products have been characterized after purification by IR, 1H NMR, 13C NMR, MS, and single crystal X-ray diffraction. 相似文献
56.
We present the results of ab initio density functional theory calculations on the energetic, and geometric and electronic structure of Li-intercalated (6,6) silicon carbide nanotube (SiCNT) bundles. Our results show that intercalation of lithium leads to the significant changes in the geometrical structure. The most prominent effect of Li intercalation on the electronic band structure is a shift of the Fermi energy which occurs as a result of charge transfer from lithium to the SiCNTs. All the Li-intercalated (6,6) SiCNT bundles are predicted to be metallic representing a substantial change in electronic properties relative to the undoped bundle, which is a wide band gap semiconductor. Both inside of the nanotube and the interstitial space are susceptible for intercalation. The present calculations suggest that the SiCNT bundle is a promising candidate for the anode material in battery applications. 相似文献
57.
In this work, we study the relativistic oscillators in a noncommutative space and in a magnetic field. It is shown that the effect of the magnetic field may compete withthat of the noncommutative space and that is able to vanish the effect of the noncommutative space. 相似文献
58.
Mandani Somayeh Sarbishaei Mohsen Javidan Kurosh 《International Journal of Theoretical Physics》2017,56(10):3244-3256
We have investigated the dynamics of a four-level N-type atom in cavity QED with consideration to the Kerr effect. The non-Markovianity of the system has been studied using the Breuer-Laine-Piilo (BLP) measure (N B L P ). Moreover the effects of system parameters like temperature and atom-field coupling have also been discussed. The evolution equation of the system has been derived using the time convolution-less(TCL) master equation. Some interesting behaviour of the system and their reasons are discussed.
相似文献59.
Nasli Esfahani Anita Iraji Aida Alamir Amir Moradi Shahram Asgari Mohammad Sadegh Hosseini Samanesadat Mojtabavi Somayeh Nasli-Esfahani Ensieh Faramarzi Mohammad Ali Bandarian Fatemeh Larijani Bagher Hamedifar Haleh Hajimiri Mir Hamed Mahdavi Mohammad 《Molecular diversity》2022,26(4):1995-2009
Molecular Diversity - A novel series of phenoxymethybenzoimidazole derivatives (9a-n) were rationally designed, synthesized, and evaluated for their α-glycosidase inhibitory activity. All... 相似文献
60.
Amir Khosravi Majid Esmhosseini Jalal Jalili Somayeh Khezri 《Journal of inclusion phenomena and macrocyclic chemistry》2012,74(1-4):383-390
The aims of the present study are to investigate removal of ammonium ion from wastewater using natural Western Azarbaijan zeolite and to optimize effective parameters by experimental design. In order to remove ammonium ions from aqueous solutions, experiments were carried out using column method as functions of the initial ammonium concentration, flow rate and pH of the solution. The results clearly confirmed that all mentioned parameters have vital affects on removing ammonium ions from wastewater and effluents, so got optimized. Central composite design with response surface methodology was applied for the optimization of main experiment parameters. The significance of the independent variables and their interactions were tested by the analysis of variance ANOVA and f-test statistics. Optimization of the variables for maximum removal efficiency by natural zeolite was performed using the quadratic model. The model predicted maximum removal efficiency under the optimum conditions including initial ammonium concentration of 30?mg?l?1; flow rate of 1?ml?min?1 and pH 6, which was very close to the experimental value determined in column experiment. The cation exchange capacity of natural Western Azarbaijan zeolite was found to be 1.79?meq?g?1. Based on the experimental results, it can be concluded that the natural Western Azarbaijan zeolite has an excellent potential for removing ammonium ions from aqueous solutions and it is suggested as a suitable material for wastewater treatment. 相似文献