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971.
Imprinted polymer particles for iron uptake: Synthesis, characterization and analytical applications
Mostafa Khajeh Massoud Kaykhaii Hossein Hashemi Majid Mirmoghaddam 《Polymer Science Series B》2009,51(9-10):344-351
This work reports the preparation of molecularly imprinted polymer particles for selective extraction and determination of iron ions from aqueous media. The polymer particles were synthesized from Fe(NO3)3, morin, 4-vinylpyridine, ethyleneglycoldimethacrylate, and 2,2′-azobisisobutyronitrile and characterized by IR and DSC both prior to and after removing the Fe-morin complex by leaching with HCl. The effect of different parameters, such as pH, adsorption and desorption time, type and minimum amount of eluent for removing the complex from polymer was evaluated and optimized. The proposed method is characterized by the detection limit of 3.1 µg l?1 anddynamic linear range of 25 to 200 µg l?1, with the relative standard deviation less than 8.8%. The method was applied to the recovery and determination of iron ions in a few real samples. 相似文献
972.
Mohammad Hossein Mashhadizadeh Abbas Shockravi Zakiyeh Khoubi Davood Heidarian 《Electroanalysis》2009,21(9):1041-1047
A new podand of 1,1′‐thia‐bis‐[1‐(chloroethan‐2‐acetamid‐α‐oxy)] naphtol was synthesized and used as a suitable carrier for Ag+ PVC membrane electrode. The electrode exhibited linear response with a Nernstian slope of (59.5±0.8 mV/decade) within a wide concentration range of 1.0×10?7 to 1.5×10?2 mol L?1 silver ions. The electrode had a fast response time of <10 s and detection limit of 8.6×10?8 mol L?1 with a working pH range from 3.7 to 9.0. The electrode was highly selective for Ag(I) ions over a large number of cations such as alkali, alkaline earth, and heavy metal ions. The proposed sensor has been applied as an indicator electrode for indirect determination of vitamin B1 in tablets by determination of Cl? ions in this compound with a standard solution of Ag(NO3). 相似文献
973.
Hossein Dehghani Elham Jafari Mohammad Reza Mansournia Fatemeh Behnoudnia 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,72(5):1034-1037
Titanium(IV) chloride reacts with free base meso-tetraarylporphyrin and its ortho, meta and para-substituted derivatives (H2T(X)PP; X: OCH3, CH3 and Cl) for formation of sitting-atop (SAT) complexes, [TiCl4(H2T(X)PP)]. The computer fitting of the variation of the absorbance versus mole ratio by KINFIT program was used for calculation of the formation constants of these complexes in chloroform. Thermodynamic parameters, ΔG°, ΔH°, ΔS°, have been determined and the influence of the temperature and the substituted aryl groups (electronic and steric effects) in the free base porphyrins on the stability of the SAT complexes was studied. 相似文献
974.
Akbar Golchin Parisa Rezaei Hossein Mohammadzadeh 《Czechoslovak Mathematical Journal》2009,59(3):595-611
By a regular act we mean an act such that all its cyclic subacts are projective. In this paper we introduce strong (P)-cyclic property of acts over monoids which is an extension of regularity and give a classification of monoids by this property
of their right (Rees factor) acts. 相似文献
975.
Marzieh Ghollasi Khosro Khajeh Hossein Naderi-Manesh Atiyeh Ghasemi 《Applied biochemistry and biotechnology》2010,162(2):444-459
Successful industrial use of amylases requires that they are sufficiently stable and active at application conditions, e.g.,
at high temperature in starch-liquefaction process. In the present study, site-directed mutagenesis was used to enhance the
thermal stability and calcium independency of a mesophilic α-amylase from Bacillus megaterium WHO. Mutations (A53S and H58I) were designed at the calcium-binding site based on the sequence alignment. Kinetic and thermostability
parameters of the mutants were analyzed and compared with that of the wild type. In the presence of calcium, the affinity
of the enzymes (wild type and mutants) toward starch was increased. In comparison to the wild type, calcium ion had more effect
on the catalytic efficiency, k
cat/K
m, and half-life (at 60 °C) of A53S mutant. In A53S, the dependence of half-life on calcium concentration showed that the enhanced
calcium binding is likely to be responsible for the increased stability. In contrast, calcium-independent mutant (H58I) possessed
high thermostability. In addition, thermodynamic parameters of amylolytic reaction exhibited an increase in the activation
energy and the entropy of the system. Kinetics of irreversible thermal inactivation suggests that the activation energy increased
by 1.4-fold in the most stable variant. 相似文献
976.
Hossein Roohi Ali‐Reza Nowroozi Fazlola Eshghi 《International journal of quantum chemistry》2010,110(8):1489-1499
The O···H? O and Cl···H? O hydrogen bonding interactions were analyzed for HOCl dimers by using B3LYP, MP2, CCSD, and MP4(SDTQ) methods in conjunction with the various basis sets. Five isomers were found for the HOCl dimer. The ZPE and BSSE corrected binding energies were computed at the different levels of theory. At the optimized geometries obtained at CCSD/AUG‐cc‐pVDZ level, energies were re‐evaluated at MP4(SDTQ)/AUG‐cc‐pVTZ and CCSD(T)/cc‐pVTZ levels of theory. We found an average of ?20.9 and ?9.6 kJ/mol for the strength of the O···H and Cl···H hydrogen bonding interactions, respectively. Excitation and vertical ionization energies as well as rotational constants were computed at different levels of theory. The quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis were used to elucidate the nature of the interactions of HOCl dimers. The interaction energies were decomposed by Morokuma methodology. We have computed ΔfH°(HOCl) and ΔfH°(HOCl+) using the atomization reactions. The ΔfH°298(HOCl) values are ?17.85 and ?18.05 kcal/mol by using CBS‐Q and CBS‐QB3 extrapolation models, respectively, in good agreement with the results given in JANAF tables. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
977.
Brownian diffusion of rod-like polymers in the presence of randomly distributed spherical obstacles is studied using molecular dynamics simulations. It is observed that dependence of the reduced diffusion coefficient of these macromolecules on the available volume fraction can be described reasonably by a power law function. Despite the case of obstructed diffusion of flexible polymers in which reduced diffusion coefficient has a weak dependence on the polymer length, this dependence is noticeably strong in the case of rod-like polymers. Diffusion of these macromolecules in the presence of obstacles is observed that is anomalous at short time scales and normal at long times. Duration time of the anomalous diffusion regime is found that increases very rapidly with increasing both the polymer length and the obstructed volume fraction. Dynamics of diffusion of these polymers is observed that crosses over from Rouse to reptation type with increasing the density of obstacles. 相似文献
978.
Solubility and diffusion of CO2 and H2S in the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate
Amir Hossein Jalili Ali Mehdizadeh Mohammad Shokouhi Amir Naser Ahmadi Masih Hosseini-Jenab Fakhrolsadat Fateminassab 《The Journal of chemical thermodynamics》2010,42(10):1298-1303
The solubility and diffusion coefficient were determined for carbon dioxide and hydrogen sulfide gases in the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) at temperatures ranging from (303.15 to 353.15) K and pressures up to 1.6 MPa. The Krichevsky–Kasarnovsky equation was used to correlate solubility data and Henry’s law constants at different temperatures were obtained. The partial molar thermodynamic functions of solution such as Gibbs free energy, enthalpy, and entropy were calculated using the solubility data. A semi-infinite volume approach is used to obtain the diffusion coefficients for CO2 and H2S and a correlation equation with temperature is presented for each gas. Comparison showed that H2S is more soluble than CO2 and its diffusion coefficient is about two orders of magnitude as that of CO2 in the ionic liquid studied in this work. 相似文献
979.
Heli Hossein Faramarzi F. Sattarahmady N. 《Journal of Solid State Electrochemistry》2010,14(12):2275-2283
The electrochemical behavior of sodium alendronate on copper microparticle- and copper nanoparticle-modified carbon paste
electrodes was investigated. In the voltammograms recorded using microparticles, a single anodic oxidation peak appeared,
while using nanoparticles, two anodic peaks appeared. The anodic currents were related to the electrocatalytic oxidation of
alendronate via the active species of Cu(III). The catalytic rate constant for the electrocatalytic oxidation process and
the diffusion coefficient of alendronate were obtained to be 1.57 × 103 cm3 mol−1 s−1 and 2.44 × 10−6 cm2 s−1, respectively. A sensitive and time-saving detection procedure was developed for the analysis of alendronate, and the corresponding
analytical parameters were reported. Alendronate was determined with a limit of detection of 11.26 μmol L−1 with a linear range of 50–6,330 μmol L−1. The proposed amperometric method was applied to the analysis of commercial pharmaceutical tablets, and the results were
in good agreement with the declared values. 相似文献
980.
Seyed Ahmad Mohajeri Hossein Hosseinzadeh Fariborz Keyhanfar Javad Aghamohammadian 《Journal of separation science》2010,33(15):2302-2309
A new molecularly imprinted polymer for extraction of crocin from saffron stigmas was prepared using gentiobiose (a glycoside moiety in crocin structure) as a template. Crocin binding to gentiobiose imprinted polymer (Gent‐MIP) was studied in comparison with a blank nonimprinted polymer in aqueous media. Affinity of the Gent‐MIP for the crocin was more than the nonimprinted polymer at all concentrations. In Scatchard analysis, the number of binding sites in each gram of polymer (maximum binding sites) and dissociation constant of crocin to binding sites were 18.4 μmol/g polymer and 11.2 μM, respectively. The Gent‐MIP was then used as the sorbent in an SPE method for isolation and purification of crocin from methanolic extract of saffron stigmas. The recovery of crocin, safranal and picrocrocin was determined in washing and elution steps. The Gent‐MIP had significantly higher affinity for crocin than other compounds and enabled selective extraction of crocin with a high recovery (84%) from a complex mixture. The results demonstrated the possibility of using a part of a big molecule in preparing a molecularly imprinted polymer with a good selectivity for the main structure. 相似文献