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31.
Abbas Afkhami Tayyebeh Madrakian Ali Shirzadmehr Hasan Bagheri Masoumeh Tabatabaee 《Ionics》2011,18(9):881-889
An effective potentiometric sensor had been fabricated for the rapid determination of Pb2+ based on carbon paste electrode consisting of room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), multiwalled carbon nanotubes (MWCNTs), nanosilica, synthesized Schiff base, as an ionophore, and graphite powder. The constructed nanocomposite electrode showed better sensitivity, selectivity, response time, response stability, and lifetime in comparison with typical Pb2+ carbon paste electrode for the successfully determination of Pb2+ ions in water and in waste water samples. The best response for nanocomposite electrode was obtained with electrode composition of 18% ionophore, 20% BMIM-PF6, 49% graphite powder, 10% MWCNT, and 3% nanosilica. The new electrode exhibited a Nernstian response (29.76?±?0.10 mV decade?1) toward Pb2+ ions in the range of 5?×?10?9?C1.0?×?10?1 mol L?1 with a detection limit of 2.51?×?10?9 mol L?1. The potentiometric response of prepared sensor is independent of the pH of test solution in the pH range of 4.5?C8.0. It has quick response with response time of about 6 s. The proposed electrode show fairly good selectivity over some alkali, alkaline earth, transition, and heavy metal ions. 相似文献
32.
Seyed-Mohammad Bagheri 《Archive for Mathematical Logic》2014,53(7-8):897-927
I study definability and types in the linear fragment of continuous logic. Linear variants of several definability theorems such as Beth, Svenonus and Herbrand are proved. At the end, a partial study of the theories of probability algebras, probability algebras with an aperiodic automorphism and AL-spaces is given. 相似文献
33.
A. Nicknam M. H. Hosseini A. Bagheri 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(12):1915-1924
The main objectives of this study are to present a vibration-based damage identification method and also a denoising mode
shape approach applicable to two-dimensional structures using curvelet transform. For this purpose, the curvelet transform
via wrapping method is employed. The reliability of the proposed technique is demonstrated through a verification study by
comparing the results of numerical and those of the experimental data in plate structures. Two case studies, one-story and
three-story shear walls assuming damages at arbitrary locations, are examined in which different noise levels are included.
Good agreement between the simulated and assumed damage in both example is demonstrated. The results confirm the robustness
and high performance of the proposed method in detecting the damage in plate structure and eliminating the noises. 相似文献
34.
Babak Bagheri L. Ridgway Scott Shangyou Zhang 《Finite Elements in Analysis and Design》1994,16(3-4):175-189
We present theoretical analyses of and detailed timings for two programs which use high-order finite element methods to solve the Navier- Strokes equations in two and three dimensions. The analyses show that algorithms popular in low-order finite element implementations are not always appropriate for high-order methods. The timings show that with the proper algorithms high-order finite element methods are viable for solving the Navier-Stokes equations. We show that it is more efficient, both in time and storage, not to precompute element matrices as the degree of approximating functions increases. We also study the cost of assembling the stiffness matrix versus directly evaluating bilinear forms in two and three dimensions. We show that it is more efficient not to assemble the full stiffness matrix for high-order methods in some cases. We consider the computational issues with regard to both Euclidean and isoparametric elements. We show that isoparametric elements may be used with higher-order elements without increasing the order of computational complexity. 相似文献
35.
A new homologous series of thermotropic polyesters has been synthesized by polycondensation reaction between isophthaloyl chloride and mesogenic diols 4,4′-bis(ω-hydroxyalkoxy)biphenyl in which the spacer length is varied from 3 to 6 methylene units. The thermal behavior of the polymers has been characterized using polarized light microscopy and differential scanning calorimetry (DSC). The odd members exhibit a smectic C (SC) phase in a narrow temperature interval, while the even members form a smectic A (SA) phase in a broader temperature range. All of the obtained compounds were characterized by conventional spectroscopic methods. 相似文献
36.
Novel thiono and seleno phosphoramidate compounds with the general formula (X)(Y)P(C6H5)2; (X = NMe2 & Y = S, 1a; X = NEt2 & Y = S, 2a; X = NMe(CH2Ph) & Y = S, 3a; X = NH(CH2Ph) & Y = S, 4a; X = NEt(CH2Ph) & Y = S, 5a; X = N(C(Me)3) (CH2Ph) & Y = S, 6a; X = N(CH2Ph)2 & Y = S, 7a; X = NMe2 & Y = Se, 1b; X = NEt2 & Y = Se, 2b; X = NMe(CH2Ph) & Y = Se, 3b; X = NH (CH2Ph) & Y = Se, 4b; X = NEt(CH2Ph) & Y = Se, 5b; X = N(C(Me)3)(CH2Ph) & Y = Se, 6b and X = N(CH2Ph)2 & Y = Se, 7b) were prepared and characterized by 1H, 31P and 13C NMR and IR spectroscopy and elemental analysis. 31P chemical shift of thiono and seleno derivatives didn’t show significant different because of their little difference in
electronegativity sulfur and selenium. Hydrophobic parameter of compounds was determined by measurement of octanol-water partition
coefficient by shake-flask technique. Determination of human erythrocyte acetylcholinesterase (hAChE) activity was carried
out according to the Ellman’s modified kinetic method. IC50 values of the selected thiono and seleno compounds varied from 3.4 to 0.11 and 9.9 to 5.1 mM, respectively. The seleno compounds
show lower affinities for hAChE relative to the thino compounds. These results demonstrate that hydrophobic and electronic
factors of the organophosphorus compounds play a key role on the inhibitory potency. 相似文献
37.
38.
Functionalization of Graphene Oxide with 3‐Mercaptopropyltrimethoxysilane and Its Electrocatalytic Activity in Aqueous Medium 下载免费PDF全文
In this work, a highly dispersed graphene oxide (GO) was successfully functionalized with 3‐mercaptopropyltrimethoxysilane (MPTS) molecule by silanization method. The chemically generated GO and MPTS functionalized GO (MPTS‐GO) were structurally characterized by thermogravimetric analysis (TGA), X‐ray diffraction analysis (XRD), scanning electron microscope (SEM), energy dispersive X‐ray (EDAX), fourier transform infrared spectroscopy (FT‐IR) and ultraviolet visible spectroscopy (UV‐Vis) techniques. The MPTS‐GO is highly suspensable in water. The thermal and conductivity results for MPTS‐GO are significantly increased compared to GO. Moreover, glassy carbon electrode modified with MPTS‐GO hybrid (MPTS‐GO/GCE) was prepared by casting of the MPTS‐GO solution on GCE. The MPTS‐GO/GCE showed an excellent electrocatalytic activity towards methionine (Met). This was understood from the observed less positive oxidation potential and higher oxidation current when compared to bare GC electrode. The MPTS‐GO has excellent electrocatalytic activity, making it an ideal candidate for sensor applications. 相似文献
39.
Ali Bagheri Jonathan Yeow Hamidreza Arandiyan Jiangtao Xu Cyrille Boyer May Lim 《Macromolecular rapid communications》2016,37(11):905-910
The polymerization of the photocleavable monomer, o‐nitrobenzyl methacrylate (NBMA), is investigated using photoinduced electron/energy transfer reversible addition‐fragmentation chain transfer polymerization. The polymerizations under visible red (λ max = 635 nm, 0.7 mW cm−2) and yellow (λ max = 560 nm, 9.7 mW cm−2) light are performed and demonstrate rational evidence of a controlled/living radical polymerization process. Well‐defined poly(o‐nitrobenzyl methacrylate) (PNBMA) homopolymers with good control over the molecular weight and polymer dispersity are successfully synthesized by varying the irradiation time and/or targeted degree of polymerization. Chain extension of a poly(oligo(ethylene glycol) methyl ether methacrylate) macro‐chain transfer agent with NBMA is carried out to fabricate photocleavable amphiphilic block copolymers (BCP). Finally, these self‐assembled BCP rapidly dissemble under UV light suggesting the photoresponsive character of NBMA is not altered during the polymerization under yellow or red light. Such photoresponsive polymers can be potentially used for the remote‐controlled delivery of therapeutic compounds.
40.
An extracting medium based on chitosan–polypyrrole (CS–PPy) magnetic nanocomposite was synthesized by chemical polymerization of pyrrole at the presence of chitosan magnetic nanoparticles (CS-MNPs) for micro-solid phase extraction. In this work, magnetic nanoparticles, the modified CS-MNPs and different types of CS–PPy magnetic nanocomposites were synthesized. Extraction efficiency of the CS–PPy magnetic nanocomposite was compared with the CS-MNPs and Fe3O4 nanoparticles for the determination of naproxen in aqueous samples, via quantification by spectrofluorimetry. The scanning electron microscopy images obtained from all the prepared nanocomposites revealed that the CS–PPy magnetic nanocomposite possess more porous structure. Among different synthesized magnetic nanocomposites, CS–PPy magnetic nanocomposite showed a prominent efficiency. Influencing parameters on the morphology of CS–PPy magnetic nanocomposite such as weight ratio of components was also assayed. In addition, effects of different parameters influencing the extraction efficiency of naproxen including desorption solvent, desorption time, amount of sorbent, ionic strength, sample pH and extraction time were investigated and optimized. Under the optimum condition, a linear calibration curve in the range of 0.04–10 μg mL−1 (R2 = 0.9996) was obtained. The limits of detection (3Sb) and limits of quantification (10Sb) of the method were 0.015 and 0.04 μg mL−1 (n = 3), respectively. The relative standard deviation for water sample spiked with 0.1 μg mL−1 of naproxen was 3% (n = 5) and the absolute recovery was 92%. The applicability of method was extended to the determination of naproxen in tap water, human urine and plasma samples. The relative recovery percentages for these samples were in the range of 56–99%. 相似文献