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61.
Adsorption kinetics, adsorption isotherms and surface complexation of trimesic acid onto alpha-alumina surfaces were investigated. Adsorption kinetics of trimesic acid with an initial concentration of 0.5 mM onto alpha-alumina surfaces were carried out in batch method in presence of 0.05 mM NaCl (aq) at pH 6 and 298.15, 303.15 and 313.15 K. Adsorption isotherms were carried out at 298.15 K, pH 5-9, and 0.05 mM NaCl (aq) by varying trimesic acid concentration from 0.01 to 0.6 mM. Three kinetics equations such as pseudo-first-order, pseudo-second-order and Ho equations were used to estimate the kinetics parameters of the adsorption of trimesic acid on the alpha-alumina surfaces. Ho equation fits the experimental kinetics data significantly better and the estimated equilibrium concentration is in excellent agreement with the experimental value. The adsorption data were fitted to Freundlich and Langmuir adsorption model and the later best fits the adsorption isotherms. Comparison of adsorption density of trimesic acid with that of benzoic and phthalic acids follows the sequence: benzoic acid < trimesic acid < phthalic acid. The negative activation energy and the Gibbs free energy for adsorption indicate that the adsorption of trimesic acid onto alpha-alumina is spontaneous and facile. DRIFT spectroscopic studies reveal that trimesate forms outer-sphere complexes with the surface hydroxyl groups that are generated onto alpha-alumina surfaces in the pH range of the study. 相似文献
62.
Asymmetric aminohydroxylation of various olefins was carried out using bromamine-T as nitrogen source in the presence of (DHQ)2PHAL ligand. The new nitrogen source has been found to be effective in terms of yield and reaction time. The optical purities of the products could be obtained with up to 99% ee. 相似文献
63.
64.
S.A.S. Ahmed B.C. Borah D. Sharma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):5-11
A transformation method has been applied to the exactly solvable Hulthen problem to generate a hierarchy of exactly solved
quantum systems in any chosen dimension. The generated quantum systems are, in general, energy-dependent with a single normalized
eigenfunction, as the Hulthen potential is a non-powerlaw potential. A method has been devised to convert a subset of the
generated quantum systems with energy-dependent potentials to a single normal system with an energy-independent potential
that behaves like a potential qualitatively similar to the Poschl-Teller potential. A second-order application of the transformation
method on the Hulthen system produces another Sturmian quantum system and a different method is given to regroup them into
a normal quantum system which resembles the Morse potential. Existence of normalizable eigenfunctions for these systems are
found to be dependent on the local and asymptotic behaviour of the transformation function.
Received 30 August 2000 and Received in final form 16 March 2001 相似文献
65.
A simple and inexpensive method for the reductive cleavage of N–O bond of benzofuroxans with bakers' yeast under nonfermenting condition in aqueous media was achieved. The procedure gives excellent yields of aryl-1,2-diamines. 相似文献
66.
In this study, we report the synthesis of several novel dihydroisoxazole-, tetrahydroisoxazole- and dihydropyrazole-fused pyrido[2,3-b]quinolines, α-carbolines, and pyrido[2,3-c]coumarins, respectively, from simple precursors and by exploring intramolecular 1,3-dipolar cycloaddition reactions involving nitrile oxides, nitrones, and nitrile imines as 1,3-dipoles. 相似文献
67.
A simple and efficient catalytic system based on Pd complex of tetradentate Schiff base ligands is found to be highly active (up to 99% isolated yield) for Suzuki–Miyaura reaction of aryl bromides with arylboronic acids in water at room temperature. Further the scope of this protocol has been extended to the Suzuki–Miyaura cross-coupling reaction of aryl chlorides with arylbronic acids in isopropanol. 相似文献
68.
Joseph Cacaccio Farukh Durrani Ravindra R. Cheruku Ballav Borah Manivannan Ethirajan Walter Tabaczynski Paula Pera Joseph R. Missert Ravindra K. Pandey 《Photochemistry and photobiology》2020,96(3):625-635
To determine the impact of delivery vehicles in photosensitizing efficacy of HPPH, a hydrophobic photosensitizer was dissolved in various formulations: 1% Tween 80/5% dextrose, Pluronic P-123 and Pluronic F-127 in 0.5%, 1% and 2% phosphate buffer solutions (PBS). HPPH was also conjugated to Pluronic F-127, and the resulting conjugate (PL-20) was formulated in PBS. Among the different delivery vehicles, only Pluronic P-123 displayed significant vehicle cytotoxicity, whereas Pluronic F127 was nontoxic. Compared to PL-20, HPPH formulated in Tween80 and Pluronic F-127 showed higher cell-uptake, but lower long-term retention in Colon26 cell compared to PL-20. The higher retention of PL-20 was similarly observed during in vivo uptake with BALB/c mice baring Ct26 tumors. In contrast to the in vitro uptake experiments, PL-20 showed slightly higher uptake compared to HPPH formulated in Tween or Pluronic-F127. A significant difference in pharmacokinetic profile was also observed between the HPPH-Pluronic formulation and PL-20. Under similar in vivo treatment parameters (drug dose 0.47 µmol kg−1, light dose: 135 J cm−2 at 24 h post-injection of PS), HPPH formulated either in Tween or Pluronic F-127 formulation showed similar in vivo PDT efficacy (20–30% tumor cure on day 60), whereas PL-20 showed 40% tumor cure (day 60). 相似文献
69.
70.
The thermal stability of linear low density polyethylene (LLDPE)/ethylene methyl acrylate (EMA) blends was studied using thermogravimetry.
The blend ratio as well as the presence of compatibilizer has significant effect on thermal stability of the blends. The compatibilization
of the blends using LLDPE-g-MA has increased the degradation temperature. Phase morphology was found to be one of the most
decisive factors that affected the thermal stability of both uncompatibilized and compatibilized blends. Dynamic mechanical
behavior of the blend was studied by dynamic mechanical analysis. The storage modulus of the blends decreased with increase
in EMA content. When compatibilized with LLDPE-g-MA the storage modulus of the blend increases. LLDPE-g-MA is an effective
compatibilizer as it increases the thermal stability and modulus of the blend. 相似文献