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61.
Preparation of highly selective solid-phase extractants for Cibacron reactive dyes using molecularly imprinted polymers 总被引:1,自引:0,他引:1
Yahya S. Al-Degs Adnan S. Abu-Surrah Khalid A. Ibrahim 《Analytical and bioanalytical chemistry》2009,393(3):1055-1062
Selective polymeric extractants were prepared for preconcentration of Cibacron reactive red dye, a dye that is often applied
with Cibacron reactive blue and Cibacron reactive yellow for dyeing of fabrics. The best extractant was fabricated (in chloroform)
using methacrylic acid (as monomer), ethylene glycol dimethacrylate (as crosslinker), AIBN (as initiator for polymerization),
and red dye as template molecule, with a molar stoichiometric ratio of 8.0:40.0:2.5:0.63, respectively. The structure of the
molecularly imprinted polymer (MIP) was robust, and resisted dissolution up to 260 °C. Compared with the un-imprinted polymer,
the imprinted product has a large specific surface area which improved its adsorption capacity. The effect of imprinting was
obvious from the adsorption capacity measured at pH 4 for red dye (the imprinted molecule), which was increased from 24.0
to 79.3 mg g−1 after imprinting. Equilibrium adsorption studies revealed that the dye-imprinted-polymer enables efficient extraction of
red dye even in the presence of blue and yellow dyes which have similar chemical natures to the red dye. The selectivity coefficients
S
red dye/dye, were 13.9 and 17.1 relative to the yellow and blue dyes, respectively. The MIP was found to be effective for red dye preconcentration,
with a preconcentration factor of 100, from tap water and treated textile wastewater. The factors affecting extraction of
red dye by the MIP were studied and optimized. Under the optimized extraction conditions, red dye was selectively quantified
in the presence of other competing dyes at a concentration of 20 μg L−1 from different water systems with satisfactory recoveries (91–95%) and RSD values (∼5.0%). 相似文献
62.
M.H.M. Rashid Yahya El-Qaderi 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(12):6276-6282
In this paper, we study the local and global existence of mild solutions to a class of fractional integro-differential equations in an arbitrary Banach space associated with operators generating compact semigroup on the Banach space. 相似文献
63.
In this work, the effect of magnetic field, rotation and initial stress on peristaltic motion of micropolar fluid in a circular cylindrical flexible tube with viscoelastic or elastic wall properties has been considered. Runge–Kutta technique are used. Runge–Kutta method is developed to solve the governing equations of motion resulting from a perturbation technique for small values of amplitude ratio. The time mean axial velocity profiles are presented for the case of free pumping and analyzed to observe the influence of wall properties, magnetic field, rotation and initial stress for various values of micropolar fluid parameters. In the case of viscoelastic wall, the effect of viscous damping on mean flow reversal at the boundary is seen. The numerical results of the time mean velocity profile are discussed in detail for homogeneous fluid under the effect of wall properties, magnetic field, initial stress and rotation for different cases by figures. The results indicate that the effect of wall properties, rotation, initial stress and magnetic field are very pronounced. Numerical results are given and illustrated graphically. 相似文献
64.
Bioassay‐guided Isolation and Antioxidant Activity of Sulfur‐containing Compounds from Clinacanthus nutans
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Hazrulrizawati Abd Hamid Izzah Hayati Yahya Mashitah M. Yusoff Seema Zareen 《中国化学会会志》2016,63(12):1033-1037
Clinacanthus nutans has been used in traditional herbal medicine for cancer prevention, but the specific bioactive compounds responsible for the observed activities have not been explored. Different polar solvents such as methanol, chloroform, ethyl acetate, and hexane were used for the extraction. The extracts, fractions, and isolated compounds were subjected to DPPH and ferric reducing antioxidant potential (FRAP) assays. Methanol extracts show significant free‐radical scavenging activity of 69.09% in DPPH and 56.49% FRAP. Purification of MeOH extracts afforded the fraction FB28 and two new sulfur‐containing compounds, named clinamide D and E ( 1 , 2 ). Compound ( 1 ) proved to be more active with an IC50 value for DPPH radical scavenging of 118.27 ± 0.01 µg/mL and reduction of Fe3+–TPTZ complex of 386.24 ± 0.02, higher than that of the standard ascorbic acid. Sulfur‐containing compounds isolated from C. nutans is a potential natural antioxidant. 相似文献
65.
K.J. Oyewumi B.J. Falaye C.A. Onate O.J. Oluwadare W.A. Yahya 《Molecular physics》2014,112(1):127-141
With the introduction of a new improved approximation scheme (Pekeris-type approximation) to deal with the centrifugal term, the energy eigenvalues and the wave functions of the Schrödinger equation of the shifted Deng–Fan molecular potential are obtained, via the asymptotic iteration method. Rotational–vibrational energy eigenvalues of some diatomic molecules are presented, these results are in good agreement with other results in the literature. For these selected diatomic molecules, energy eigenvalues obtained are in much better agreement with the results obtained from the rotating Morse potential model for moderate values of rotational and vibrational quantum numbers. Furthermore, thermodynamic properties such as the vibrational mean U, specific heat C, free energy F and entropy S for the pure vibrational state in the classical limit for these energy eigenvalues are studied. 相似文献
66.
Wajid Hussain Muhammad Shahid Iqbal Hui Li Muhammad Sulaman Honglian Guo Chuanbo Li Yahya Sandali Ahmad Irfan Hafiz Saqib Ali 《International journal of quantum chemistry》2024,124(1):e27223
Perylene diimide (PDI) and naphthalene diimides (NDIs) are compounds widely used in supramolecular structures due to their versatile and functional properties. They have high absorptions and photoluminescence capabilities, which make them ideal for electronic transition studies. Reflux method, a widely employed synthetic technique, was utilized to synthesize NDI and PDI derivatives. In this method, the respective amino acids and NTDA (naphthalene-1,4,5,8-tetracarboxylic dianhydride) were combined in acetic acid and the resulting mixture was subjected to reflux. This study centered on a diverse set of NDI and PDI ligands, comprising L-ala-NDI, B-ala-NDI, Gly-NDI, Imi-NDI, Pyr-NDI, L-ala-PDI, B-ala-PDI, Gly-PDI, Imi-PDI, and Pyr-PDI ligands. Crystal structures were obtained for three NDI ligands, while the characterization of all ligands involved several analytical techniques such as NMR, IR, UV, DFT, TD-DFT calculations, and single-crystal x-ray crystallography specifically for the NDI ligands. The investigation focused on studying the electron acceptor/donor behavior of the NDI and PDI ligands, identifying their potential for charge transfer applications. Furthermore, the NLO (nonlinear optical) response of all 10 NDI and PDI ligands was assessed through an analysis involving HOMO-LUMO, TDM, EDDM, NCI, Iso-surface, MEP, natural population, and DOS analysis. This evaluation encompassed the examination of linear polarizability, as well as first and second hyperpolarizability in the context of NLO. The findings of the study revealed that Gly-PDI, Imi-PDI, L-ala-PDI, and B-ala-PDI ligands displayed a higher NLO response compared with the other ligands. These results highlight the potential of these ligands for nonlinear optical applications. The comprehensive characterization and assessment of the NDI and PDI ligands contribute to a deeper understanding of their electron properties, positioning them as promising candidates for charge transfer and nonlinear optical materials. 相似文献
67.
Yahya ZAMANI Mehdi BAKAVOLI Mohamad RAHIMIZADEH Ali MOHAJERI Seyed Mohamad SEYEDI 《催化学报》2012,(7):1119-1124
Effect of promoters such as Barium and Lanthanum has been investigated on the conventional nanostructured iron catalyst in Fischer-Tropsch synthesis (FTS). The nanosized iron-based catalysts were prepared by a microemulsion method with the general formulation of 100Fe/4Cu, 100Fe/4Cu/2La, 100Fe/4Cu/ 1La/1Ba, and 100Fe/4Cu/2Ba. The phase, structure, and morphology of the catalysts were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature-programmed desorption of CO2, and temperature- programmed reduction. The results indicated that the addition of promoters could improve the activity of Fe catalysts for FTS and WGS (water-gas shift reaction) and lower the gas fraction at the outlet. In addition, both Ba- and La-promoted Fe catalysts exhibit the highest activity due to the synergetic effect. 相似文献
68.
Ternary tellurite glasses with the chemical formula 80TeO2–(2 ? x)ZnO–xFe2O3 (x = 0–15 mol%) have been prepared by the melt-quenching method. Elastic and structural properties of the glasses were investigated by measuring both longitudinal and shear velocities using the pulse-echo overlap method at 5 MHz and Fourier transform infrared (FTIR) spectroscopy, respectively. Both longitudinal and shear velocity showed a large increase of 3.40% and 4.68%, respectively, at x = 5 mol% before a smaller increase for x > 5 mol%. Interestingly, longitudinal modulus (L), shear modulus (G), bulk modulus (K) and Young's modulus (E) recorded similar trends with increase in Fe2O3. The initial large increases in shear and longitudinal velocity and related elastic moduli observed at x = 5 mol% are suggested to be due to structural modification which enhances rigidity of the glass network. FTIR analysis showed increase in bridging oxygen (BO) as indicated by the relative intensity of the TeO4 assigned peaks and increase in intensity of the FeO6 assigned peak (~ 451 cm? 1) which indicates that Fe acts as a modifier in the glass network. The increase in rigidity of the glass system is suggested to be due to the increase of BO together with the formation of strong covalent FeO bond. Quantitative analysis based on the bulk compression and ring deformation models showed that the kbc/kexp value decreased gradually from 2.41 (x = 0 mol%) to 2.02 (x = 15 mol%) which infers that the glass system became a relatively more open 3D network as Fe2O3 was increased. 相似文献
69.
Rahim Hekmatshoar Issa Yavari Yahya S. Beheshtiha Majid M. Heravi 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):689-691
Summary. In the presence of metallic zinc, aldehydes and ketones experience reductive coupling in tetrahydrofuran-saturated aqueous
ammonium chloride (5:3) to afford the corresponding pinacols in moderate to high yields.
Received October 23, 2000. Accepted (revised) December 12, 2000 相似文献
70.
Gholami Aysan Ajabshirchi Yahya Ranjbar Seyed Faramarz 《Journal of Thermal Analysis and Calorimetry》2019,138(2):1395-1403
Journal of Thermal Analysis and Calorimetry - In this study, thermo-economic optimization of single-pass SAHs (solar air heaters) with obstacles of arcuate shape has been carried out. The research... 相似文献