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151.
Mohsen Taghizadeh Ali Akbar Asgharinezhad Mohsen Pooladi Mahnaz Barzin Abolfazl Abbaszadeh Azadeh Tadjarodi 《Mikrochimica acta》2013,180(11-12):1073-1084
We describe a novel magnetic metal-organic framework (MOF) prepared from dithizone-modified Fe3O4 nanoparticles and a copper-(benzene-1,3,5-tricarboxylate) MOF and its use in the preconcentration of Cd(II), Pb(II), Ni(II), and Zn(II) ions. The parameters affecting preconcentration were optimized by a Box-Behnken design through response surface methodology. Three variables (extraction time, amount of the magnetic sorbent, and pH value) were selected as the main factors affecting adsorption, while four variables (type, volume and concentration of the eluent; desorption time) were selected for desorption in the optimization study. Following preconcentration and elution, the ions were quantified by FAAS. The limits of detection are 0.12, 0.39, 0.98, and 1.2 ng mL?1 for Cd(II), Zn(II), Ni(II), and Pb(II) ions, respectively. The relative standard deviations were <4.5 % for five separate batch determinations of 50 ng mL?1 of Cd(II), Zn(II), Ni(II), and Pb(II) ions. The adsorption capacities (in mg g?1) of this new MOF are 188 for Cd(II), 104 for Pb(II), 98 Ni(II), and 206 for Zn(II). The magnetic MOF nanocomposite has a higher capacity than the Fe3O4/dithizone conjugate. This magnetic MOF nanocomposite was successfully applied to the rapid extraction of trace quantities of heavy metal ions in fish, sediment, soil, and water samples. Figure
A schematic diagram for synthesis of magnetic MOF-DHz nanocomposite. 相似文献
152.
One-pot, three-component reaction of 2-naphthol, aromatic aldehyde, and heteroaryl amine in water at room temperature leads to the formation of the corresponding aminonaphthols (Betti bases). Reaction details and study of enantiomeric resolution of 1-(p-methylphenyl (2-pyrazinylamino) methyl) naphthalene-2-ol with the aid of 1H NMR spectroscopy using chiral europium shift reagent is presented. 相似文献
153.
Abolfazl Tarizadeh 《代数通讯》2019,47(1):195-205
In this article, a new and natural topology on the prime spectrum is introduced, which behaves completely as the dual of the Zariski topology. It is called the flat topology. The basic and also some sophisticated properties of the flat topology are proved. Specially, various algebraic characterizations for the noetherianess of the flat topology are given. Using the flat topology, then some facts on the structure of the prime ideals of a ring come to light which are not in the access of the Zariski topology. 相似文献
154.
Mehdi Ghandi Elham MohammadimehrMasoud Sadeghzadeh Abolfazl Hasani Bozcheloei 《Tetrahedron》2011,67(44):8484-8491
An efficient catalyst-free, diastereosective synthesis of novel hexahydro-chromene and tetrahydro-pyrano[2,3-d]pyrimidine-annulated benzo-δ-sultones is described. A number of 2-formyl-4-phenyl (E)-2-phenylethenesulfonates were synthesized and underwent a one-pot domino Knöevenagel-hetero-Diels-Alder reaction, respectively, with dimedone and N,N-dimethylbarbituric acid in water, affording the desired products in moderate to excellent yields. 相似文献
155.
An efficient and multicomponent method has been developed for the synthesis of functionalized tricarboxamides at room temperature using CuI nanoparticles as catalyst. This method involved fivecomponent coupling reactions of Meldrum's acid, isocyanides with aromatic aldehydes and amines at room temperature. Atom economy, wide range of products, excellent yields in short time and mild reaction conditions are some of the important features of this protocol. Notably, this catalyst could be recycled and reused for several times without significantly decreasing the catalytic activity. 相似文献
156.
Mohammad Hossein Keshavarz Narges Zohari Seyed Abolfazl Seyedsadjadi 《Journal of Thermal Analysis and Calorimetry》2013,114(2):497-510
This study presents a new simple model for predicting activation energy of the thermolysis of various classes of energetic compounds. The new model can help to elucidate the cause of thermal stability and, therefore, shelf life of some energetic compounds. The methodology assumes that activation energy of an energetic compound with general formula C a H b N c O d can be expressed as a function of optimized elemental composition as well as the contribution of specific molecular structural parameters. The new correlation has the root mean square and the average deviations of 9.8 and 7.4 kJ mol?1, respectively, for 86 energetic compounds with different molecular structures. The proposed new method is also tested for 20 energetic compounds, which have complex molecular structures, e.g. 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane, 2,4,6-tris(2,4,6-Trinitrophenyl)-1,3,5-triazine and 1-(2,4,6-Trinitrophenyl)-5,7-dinitrobenzotriazole. 相似文献
157.
Mohammad Rezaee Hossein Ali Mashayekhi Abolfazl Saleh Yaser Abdollahzadeh Mohammad Hosein Naeeni Nazir Fattahi 《Journal of separation science》2013,36(16):2629-2634
A new pretreatment method, SPE combined with dispersive liquid–liquid microextraction, was proposed for the determination of abamectin in citrus fruit samples for the first time. In this method, fruit samples were extracted by ultrasound‐assisted extraction followed by SPE. Then, the SPE was used as a disperser solvent in the next dispersive liquid–liquid microextraction step for further purification and enrichment of abamectin. The effects of various parameters on the extraction efficiency of the proposed method were investigated and optimized. Good linearity of abamectin was obtained from 0.005 to 10.0 mg/kg for B1a and from 0.05 to 10.0 mg/kg for B1b with correlation coefficient (r2) of 0.998 for B1a and 0.991 for B1b, respectively. The LODs were 0.001 and 0.008 mg/kg (S/N = 3) for B1a and B1b, respectively. The relative recoveries at three spiked levels were ranged from 87 to 96% with the RSD less than 11% (n = 3). The method has been successfully applied to the determination of abamectin in citrus fruit samples. 相似文献
158.
Kurt J. Schenk Soraia Meghdadi Mehdi Amirnasr Mohammad H. Habibi Ahmad Amiri Mehdi Salehi Abolfazl Kashi 《Polyhedron》2007,26(18):5448-5457
The synthesis and characterization of a series of cobalt(III) complexes of the general type [Co(N2O2)(L2)]+ are described. The N2O2 Schiff base ligands used are Me-salpn (H2Me-salpn = N,N′-bis(methylsalicylidene)-1,3-propylenediamine) (1–3) and Me-salbn (H2Me-salbn = N,N′-bis(methylsalicylidene)-1,4-butylenediamine) (4–5). The two ancillary ligands L include: pyridine (py) 1, 3-metheylpyridine (3-Mepy) 2, 1-methylimidazole (1-MeIm) 3, 4-methylpyridine (4-Mepy) 4 and pyridine (py) 5. These complexes have been characterized by elemental analyses, IR, UV–Vis, and 1H NMR spectroscopy. The crystal structures of trans-[CoIII(Me-salpn)(py)2]PF6, 1, and cis-α-[CoIII(Me-salbn)(4-Mepy)2]BPh4 · 4-Mepy, 4, have been determined by X-ray diffraction. Examination of the solution and crystalline structures revealed that the outer coordination sphere of the complexes exerts a noticeable influence on the inner coordination sphere of the Co(III) ion. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to CoIII–CoII is electrochemically irreversible, which is accompanied by the dissociation of the axial (R-py)–cobalt bonds. It has also been observed that the Co(III) state is stabilized with increasing the flexibility of the ligand environment. 相似文献
159.
Abolfazl Alizadeh Sahraei Alireza Fathi Mohammad Kazem Besharati Givi Mohammad Hadi Pashaei 《Applied Physics A: Materials Science & Processing》2014,116(4):1677-1686
In this study, copper (Cu) nanocomposites reinforced by coated multiwall carbon nanotubes (MWCNTs) have been fabricated with different weight fractions of MWCNT. In the first step, the as-received MWCNTs were coated with Cu using electroless deposition process. In the next step, combination of sonication and ball milling (with two milling time of 1.5 and 3 h) was used for preparing MWCNT/Cu composite powders. Finally, the disk-shaped specimens were sintered by hot-press sintering machine. Characterization of sintered nanocomposites revealed that increasing milling time led to improved mechanical properties, but higher defect density on the MWCNT sidewalls is obtained which is especially undesirable for electrical properties of nanocomposite. Our results indicated that simultaneous improvements of interface reactions and distribution uniformity of MWCNTs and Cu are key factors for obtaining enhanced mechanical properties. Accordingly, enhancement of up to ~150 and ~86 % in microhardness compared to pure Cu and 1 wt% as-received MWCNT/Cu was achieved by addition of 1 wt% Cu-coated MWCNT. On the contrary, existence of oxygen atoms in the Cu and coated MWCNT interface (from functional groups and deposited copper oxide) obstructs considerable improvement of electrical resistivity compared to as-received MWCNT/Cu nanocomposites. 相似文献
160.
Seyed Abolfazl Hosseini‐Yazdi Ali Akbar Khandar Hashem Azizi Amir Reza Aref 《无机化学与普通化学杂志》2008,634(11):1943-1949
The 18‐membered mixed‐donor macrocycle 6,7,8,9,10,11,12,13,20,21‐decahydro‐5H, 19H‐dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecin‐20‐ol ( L ), which contains N3O3 donor set, was synthesized. Also two nickel(II) complexes of L have been synthesized and characterized by X‐ray crystallography, FT‐IR, UV‐Vis absorption spectroscopy and elemental analysis. The structure of complexes shows an unexpected anion dependence. Reaction of Ni(ClO4)2·6H2O with L afforded [Ni L ](ClO4)2·CH2Cl2 complex in which L uses all donor atoms and acts as a hexadentate ligand so forming a mononuclear nickel(II) complex in distorted octahedral geometry. Contrasting with this, when NiCl2·6H20 is used, the product complex [{Ni L Cl}2(μ‐Cl)2] is dimeric and consists of two Ni L Cl units bridged by two chloride ions. The coordination geometry of each nickel atom is a distorted octahedral. In this complex L is exo‐coordinated via only three nitrogen atoms to a nickel ion, which is bound to two cis bridging chloride and one non‐bridging chloride too. Also complexing properties of L towards Ni(ClO4)2·6H2O and NiCl2·6H20 have been determined by UV‐Vis titration in methanol. The computer treatment of the data confirmed the 1:1 metal to ligand stoichiometry for two complexes in solution and gave reliable values for corresponding stability constants (logK = 3.00 ± 0.02 with Ni(ClO4)2·6H2O and logK = 3.29 ± 0.06 with NiCl2·6H20). 相似文献