排序方式: 共有124条查询结果,搜索用时 15 毫秒
31.
H. Akhavan Kashani J. A. Barrie M. H. George 《Journal of polymer science. Part A, Polymer chemistry》1978,16(3):533-537
Nylon 66 [poly(hexamethylene adipamide)] and Nomex [poly(m-phenylene isophthalamide)] were metalated by using solutions of sodium in liquid ammonia. Metalation of the Nomex polymer was also carried out by using sodium naphthalene in tetrahydrofuran. The metalated polymers were then reacted with acrylonitrile monomer to yield the corresponding anionic graft copolymers. The heterogeneous nature of these reactions is discussed in relation to the structure of the graft copolymers. 相似文献
32.
Mohsen Asadnia Matthew Myers N.D. Akhavan Kane O'Donnell Gilberto A. Umana-Membreno U.K. Mishra Brett Nener Murray Baker Giacinta Parish 《Analytica chimica acta》2016
This work presents the first polymer approach to detect metal ions using AlGaN/GaN transistor-based sensor. The sensor utilised an AlGaN/GaN high electron mobility transistor-type structure by functionalising the gate area with a polyvinyl chloride (PVC) based ion selective membrane. Sensors based on this technology are portable, robust and typically highly sensitive to the target analyte; in this case Hg2+. This sensor showed a rapid and stable response when it was introduced to solutions of varying Hg2+ concentrations. At pH 2.8 in a 10−2 M KNO3 ion buffer, a detection limit below 10−8 M and a linear response range between 10−8 M-10−4 M were achieved. This detection limit is an order of magnitude lower than the reported detection limit of 10−7 M for thioglycolic acid monolayer functionalised AlGaN/GaN HEMT devices. Detection limits of approximately 10−7 M and 10−6 M in 10−2 M Cd(NO3)2 and 10−2 M Pb(NO3)2 ion buffers were also achieved, respectively. Furthermore, we show that the apparent gate response was near-Nernstian under various conditions. X-ray photoelectron spectroscopy (XPS) experiments confirmed that the sensing membrane is reversible after being exposed to Hg2+ solution and rinsed with deionised water. The success of this study precedes the development of this technology in selectively sensing multiple ions in water with use of the appropriate polymer based membranes on arrays of devices. 相似文献
33.
Various hydrogen-bonded clusters of 2-methoxyphenol (2MP) with water have been analyzed using ab initio methods and Atoms
in Molecules (AIM) theory. The intramolecular hydrogen bond energy (and enthalpy) for 2MP was evaluated from two different
methods. The results of rotational barriers method are in better agreement with experimental data. Binding energies, vibrational
frequencies and geometrical parameters were examined and compared for these complexes. It was shown that in the most stable
complex, water acts both as a donor and an acceptor. The “bifurcated” complex was shown to be relatively stable based on energy
values. Atoms in Molecules and Natural Bond Orbital (NBO) analysis were used to confirm the existence of hydrogen bonds and
to compare the strengths of them. The results obtained from quantum mechanical, AIM and NBO calculations are in agreement
with each other. 相似文献
34.
35.
Hamid Khanmohammadi Malihe Erfantalab 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):127-133
Six pyridazine-based Schiff base ligands, H2Ln (n = 1–5) and H4L, with N4O2S2 and N4O4S2 donor set atoms, respectively, were prepared by condensation reaction of 3,6-bis-((2-aminoethyl)thio)pyridazine with various salicyladehyde derivatives in ethanol and under solvent-free polyphosphate ester catalyzed conditions. The acid–base properties of H2L2 and H2L3 in DMSO/water (1:1) solution have been studied by spectrophotometric method at 25 °C. Optimized geometries of all compounds were also obtained at the B3LYP level of theory. Additionally, the 13C chemical shielding of gas phase H2L1 and H2L2 were studied by the gauge independent atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) methods at the level of density functional theory (DFT). The 6-311++G* basis set was utilized for all of the atoms. 相似文献
36.
Malihe S. Kazemi Golamhossein Rounaghi 《Russian Journal of Inorganic Chemistry》2010,55(12):1987-1991
The liquid membrane transport of Pb2+ cation using decyl-18-crown-6 as selective ion carrier was studied. The transport of lead ion across the liquid membrane in the presence of S2O 3 2? , P2O 7 4? , CN?, SCN?, and DDC? as stripping agents in the receiving phase shows that the nature and the concentration of the stripping agents affect on Pb2+ cation transport and the maximum transport occurs when the sodium thiosulfate (Na2S2O3) was used. The effects of various parameters influencing the transport efficiency such as the pH of the source and receiving phases, the concentration of picrate ion as counter ion in the source phase were also studied. Five replicated experiments show that a value 82.12 ± 2.09% of the initial concentration of the Pb2+ cation in the source phase is extracted into the receiving phase after 4 hours. Also the selectivity and efficiency of lead ion transport from the source phase containing equimolar mixtures of Na+, K+, Ca2+, Ni2+, Cu2+, Cd2+ and Ag+ metal cations were investigated. 相似文献
37.
38.
H. Hadipour M. Akhavan 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(2):203-217
We have investigated the role of electron-electron correlation in SrRuO3 and CaRuO3 bulk structures. At first, the DOS of SrRuO3 and CaRuO3 is obtained using the full potential linearized augmented plane wave method by LSDA. We have then calculated the electronic
structure, dielectric function, self-energy, and spectral function for the bulk SrRuO3 and CaRuO3 by GWA. The shifting of the Ru t
2g
orbitals, broadening in Ru valance bands, and also the enhancement in exchange splitting shows better agreement between the
GWA many-body correction with the bulk experimental results. But, in spite of the many-body correction, the GWA results is
not completely consistent with the PES experimental results due to small shifting of the Ru t
2g
bands and small broadening of the valance states specially in the Ca-based system. Inclusion of Coulomb correlation by LSDA+U for both Sr- and Ca-based compounds shows significant difference in the results as compared with the LSDA and GWA calculations,
and is consistent with the PES results. So, the discrepancy between the bulk ab-initio calculation and experiment is attributed
to the surface effects which is not considered in the both LSDA and GWA bulk calculations. Due to the more distorted structure
of CaRuO3, electron correlation at surface in the Ca-based system is more important than that in the Sr-based system. Hence, the bulk
character of both SrRuO3 and CaRuO3 experimental results can be well described by GWA. 相似文献
39.
Ali A. Ensafi Malihe Monsef Behzad Rezaei Hassan Karimi-Maleh 《Journal of Analytical Chemistry》2014,69(9):892-898
A sensitive and selective electrochemical method was developed for the determination of glutathione (GSH) in hemolysed erythrocyte using vinylferocene modified carbon nanotubes paste electrode (VFMCNTPE). The results indicate that the electrode is efficient in terms of its electrocatalytic activity for the oxidation of GSH, leading to a reduced overpotential by more than 470 mV. Also, the values of catalytic rate constant (k), and diffusion coefficient (D) for GSH were calculated. The electrocatalytic oxidation peak current of GSH showed two linear dynamic ranges with a detection limit of 0.09 μM GSH. The linear calibration ranges were obtained between 0.2–4.0 and 4.0–250.0 μM GSH using square wave voltammetry (SWV) method. The proposed method was also examined as a selective, simple and precise electrochemical sensor for the determination of GSH in real samples such as urine and hemolysed erythrocyte. 相似文献
40.
The catalytic efficiency of ammonium dihydrogenphosphate was evaluated in the two heterogeneous forms of NH4H2PO4/MCM‐48 and NH4H2PO4/MCM‐41, as mesoporous catalysts, in the solvent free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones through one‐pot three‐component condensation of ethyl acetoacetate, an aryl aldehyde and urea. Different reaction parameters including catalytic efficacy, solvent effect, and urea concentration are considered. 相似文献