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81.
Evaluation of sorption of uranium onto metakaolin using X-ray photoelectron and Raman spectroscopies
Metakaolin prepared from a natural clay mineral ore of aluminium kaolinite is a promising low cost and high activity aluminosilicate material that has been investigated for studying the sorption behavior of uranium. Here, metakaolin was characterized using X-ray photoelectron spectroscopy (XPS) and the effects of pH, contact time and initial metal ion concentration on its sorption behavior were studied. The sorption process was found to initially be rapid (∼60% at time 0 min) but became slower with time; equilibrium was established within 24 h (∼80% sorption). The data were applied to study the kinetics of the sorption process. The Langmuir and Dubinin-Radushkevich (D-R) sorption isotherms were used to describe partitioning behavior for the system at room temperature. The binding of metal ions was found to be pH dependent, with optimal sorption occurring at pH 5. The retained metal ions were eluted with 5 mL of 0.1 M HNO3. Raman spectroscopy and XPS were used to evaluate the sorption mechanism of U(VI). 相似文献
82.
Jamil Rima Soula Kyriacos Maurice Abou Rida 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):10-15
The solubilization of pyrene in aqueous solution of β-cyclodextrin (β-CD) or its derivatives such as β-CD-hexanoyl, β-CD-benzoyl and β-CD-dodecylsulfonate was investigated by spectrophotometry. Linear and non-linear regression methods were used to estimate the association constants (K1). A 1:1 stoichiometric ratio and different effects of the hexanoyl, benzoyl and dodecylsulfonate groups on the association constant were observed for the binary inclusion complex between pyrene and β-CD. The formation constant was shown to decrease when β-CD was modified by a dodecylsulfonate chain. The value of K1 was 190 ± 10 L mol−1 for the [pyrene/β-CD] complex and 145 L mol−1 for the [pyrene/β-CD-dodecylsulfonate] complex. Partitioning of the pyrene molecules between the dodecylsulfonate chains and cyclodextrin cavities can explain the decrease in the association constant value. In the cases of β-CD-hexanoyl and β-CD-benzoyl derivatives, no association constants were detected. Results suggest that the high hydrophobicity of the hexanoyl and benzoyl groups prevents the inclusion of pyrene molecules inside the cyclodextrin cavity. 相似文献
83.
Corina Fetecau Muhammad Jamil Constantin Fetecau Dumitru Vieru 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,25(6):921-933
The velocity field corresponding to the Rayleigh–Stokes problem for an edge, in an incompressible generalized Oldroyd-B fluid
has been established by means of the double Fourier sine and Laplace transforms. The fractional calculus approach is used
in the constitutive relationship of the fluid model. The obtained solution, written in terms of the generalized G-functions, is presented as a sum of the Newtonian solution and the corresponding non-Newtonian contribution. The solution
for generalized Maxwell fluids, as well as those for ordinary Maxwell and Oldroyd-B fluids, performing the same motion, is
obtained as a limiting case of the present solution. This solution can be also specialized to give the similar solution for
generalized second grade fluids. However, for simplicity, a new and simpler exact solution is established for these fluids.
For β → 1, this last solution reduces to a previous solution obtained by a different technique. 相似文献
84.
Hantash J Bartlett A Oldfield P Dénès G O'Rielly R Roudiere D Menduni S 《Journal of chromatography. A》2006,1125(1):104-111
A carbaryl and 1-naphtol molecular imprinted polymers (MIP1 and MIP 2, respectively) were prepared using suspension polymerization and tested for selective and reversible binding to carbaryl and 1-naphtol, respectively. In the suspension polymerization technique used, polymers of methacrylic acid (MAA), highly cross-linked with ethylene dimethacrylate, provide a specific binding sites for the carbaryl molecule and its metabolite when using it as a template to be removed after polymerization. The molecular imprinted polymer with a particle size of approximately 5 microm were isolated and packed into a pre-column (50 mm x 4.6 mm id) that was used to isolate carbaryl and its metabolite from complex matrices injected on a high performance liquid chromatography system using ultra-violet detection without extensive sample preparation and clean up. The HPLC method had a detection limit of 1.00 ng/mL and a linear response (r2 > 0.98) over the concentration range of 1.00-10.0 ng/mL. 相似文献
85.
This paper establishes the velocity field and the adequate shear stress corresponding to the motion of an Oldroyd-B fluid between two infinite coaxial circular cylinders by means of finite Hankel transforms. The flow of the fluid is produced by the inner cylinder which applies a time-dependent longitudinal shear stress to the fluid. The exact analytical solutions, presented in series form in terms of Bessel functions, satisfy all imposed initial and boundary conditions. The general solutions can be easily specialized to give similar solutions for Maxwell, second grade and Newtonian fluids performing the same motion. Finally, some characteristics of the motion as well as the influence of the material parameters on the behavior of the fluid motion are graphically illustrated. 相似文献
86.
Farook Rahaman Ayan Banerjee Mubasher Jamil Anil Kumar Yadav Humaira Idris 《International Journal of Theoretical Physics》2014,53(6):1910-1919
In this paper, we derive some new exact solutions of static wormholes in f(R) gravity supported by the matter possesses Lorentzian density distribution of a particle-like gravitational source. We derive the wormhole’s solutions in two possible schemes for a given Lorentzian distribution: assuming an astrophysically viable F(R) function such as a power-law form and discuss several solutions corresponding to different values of the exponent (here $F =\frac{df}{dR}$ ). In the second scheme, we consider particular form of two shape functions and have reconstructed f(R) in both cases. We have discussed all the solutions with graphical point of view. 相似文献
87.
Khalid Mohammed Khan Muhammad Taha Fazal Rahim Waqas Jamil Shahnaz Perveen Muhammad Iqbal Choudhary 《Journal of the Iranian Chemical Society》2012,9(1):81-83
Treatment of indole with substituted aldehyde in the presence of equimolar amount of sodium bromate and sodium hydrogen sulfite mixture in water yielded corresponding substituted bis(indolyl)methanes in good yields. This provides a facile and environmentally friendly method towards the synthesis of an important class of organic compounds. 相似文献
88.
We study the evolution of primordial black holes by considering present universe is no more matter dominated rather vacuum energy dominated. We also consider the accretion of radiation, matter and vacuum energy during respective dominance period. In this scenario, we found that radiation accretion efficiency should be less than 0.366 and accretion rate is much larger than previous analysis by Nayak et al. (2009) [1]. Thus here primordial black holes live longer than previous works Nayak and Singh (2011) [1]. Again matter accretion slightly increases the mass and lifetime of primordial black holes. However, the vacuum energy accretion is slightly complicated one, where accretion is possible only up to a critical time. If a primordial black hole lives beyond critical time, then its? lifespan increases due to vacuum energy accretion. But for presently evaporating primordial black holes, critical time comes much later than their evaporating time and thus vacuum energy could not affect those primordial black holes. 相似文献
89.
Jamil Mortada 《Geometriae Dedicata》2012,158(1):283-300
For every integer ? ?? 2, we find elements x and y in the mapping class group of an appropriate orientable surface S, satisfying the Artin relation of length ?. That is, xyx ... =?yxy ..., where each side of the equality contains ? terms. By direct computations, we first find elements x and y in Mod(S) satisfying Artin relations of every even length ?? 8, and every odd length ???3. Then using the theory of Artin groups, we give two more alternative ways for finding Artin relations in Mod(S). The first provides Artin relations of every length ?? 3, while the second produces Artin relations of every even length ?? 6. 相似文献
90.
Afsheen Ayaz QurratUlAin Jamil Musaddique Hussain Fayyaz Anjum Adeel Sarfraz Taha Alqahtani Nadia Hussain Reem M. Gahtani Ayed A. Dera Hanan M. Alharbi Shahid M. Iqbal 《Molecules (Basel, Switzerland)》2022,27(14)
Suaeda fruticosa Forssk. Ex J.F.Gmel is traditionally used for inflammatory and digestive disorders, as a carminative, and for diarrhea. This plant is widely distributed in Asia, Africa, and the Mediterranean region. Aqueous methanolic extract of S. fruticosa (Sf.Cr) was prepared and screened for phytoconstituents through qualitative and GC-MS analysis. Quantification of total phenolic and flavonoid contents was performed, while antioxidant capacity was determined by DPPH, CUPRAC, FRAP, and ABTS assays. The gastroprotective activity was assessed in an ethanol-induced ulcer model. Gastric secretory parameters and macroscopic ulcerated lesions were analyzed and scored for ulcer severity. After scoring, histopathology was performed, and gastric mucus contents were determined. Oral pre-treatment of Sf.Cr demonstrated significant gastroprotection. The gastric ulcer severity score and ulcer index were reduced while the %-inhibition of ulcer was increased dose-dependently. The Sf.Cr significantly elevated the pH of gastric juice, while a decrease in total acidity and gastric juice volume was observed. Histopathology demonstrated less oedema and neutrophil infiltration in gastric mucosa of rats pre-treated with the Sf.Cr in comparison to ethanol-intoxicated animals. Furthermore, the gastric mucus contents were increased as determined by alcian blue binding. Sf.Cr showed marked gastroprotective activity, which can be attributed to antioxidant, antisecretory, and cytoprotective effects. 相似文献