排序方式: 共有106条查询结果,搜索用时 31 毫秒
41.
Gueorguieva L Palani S Rinas U Jayaraman G Seidel-Morgenstern A 《Journal of chromatography. A》2011,1218(37):6402-6411
In the first part of this work adsorption isotherm parameters were acquired to describe the migration of recombinant streptokinase in Butyl Sepharose columns at different salt concentrations. Based on these results, a simulated moving bed (SMB) chromatographic process was designed and realised, which exploits a two-step salt gradient and allows the continuous separation of streptokinase from contaminants present in a clarified Escherichia coli cell lysate solution. This second part describes the design of the three-zone open-loop gradient SMB process applying both equilibrium theory and an equilibrium stage model and presents results of a series of experiments aiming to obtain pure streptokinase. Moreover, the potential of the SMB process and the design approach are evaluated. 相似文献
42.
Palani S Gueorguieva L Rinas U Seidel-Morgenstern A Jayaraman G 《Journal of chromatography. A》2011,1218(37):6396-6401
The design of gradient simulated moving bed (SMB) chromatographic processes requires an appropriate selection of the chromatographic system followed by the determination of adsorption isotherm parameters in the relevant range of mobile phase conditions. The determination of these parameters can be quite difficult for recombinant target proteins present in complex protein mixtures. The first part of this work includes the estimation of adsorption isotherm parameters for streptokinase and a lumped impurity fraction present in an Escherichia coli cell lysate for a hydrophobic interaction chromatography (HIC) matrix. Perturbation experiments were carried out using a Butyl Sepharose matrix with purified recombinant protein on buffer equilibrated columns as well as with crude cell lysate saturated columns. The Henry constants estimated for streptokinase were found to exhibit in a wide range a linear dependence on the salt concentration in the mobile phase. These parameters were applied in subsequent investigations to design a simulated moving bed (SMB) process capable to purify in a continuous manner recombinant streptokinase from the E. coli cell lysate. 相似文献
43.
In the present analysis, a numerical study is performed to examine the heat transfer characteristics of a convective flow over a vertical plate under the combined effects of magnetic field and thermal radiation in the presence of heat source/sink. The surface of the plate is subjected to a variable surface temperature. The boundary layer equations governing the flow are reduced to non-dimensional equations valid in the free convection regime using the suitable non-dimensional parameters. The dimensionless governing equations are solved by an implicit finite difference method of Crank—Nicolson type which is fast convergent, more accurate and unconditionally stable. Numerical results are obtained and presented for velocity, temperature, local and average wall shear stress, local and average Nusselt number in air. The present results are compared with the results available in the literature and are found to be in an excellent agreement. 相似文献
44.
Free convection flow over an isothermal vertical cone immersed in a fluid with variable viscosity and MHD is studied in this paper. Using appropriate variables, the basic equations are transformed into the non-dimensional boundary-layer equations. These equations are then solved numerically using a very efficient implicit finite-difference method known as Crankl-Nicolson scheme. Detailed results for the velocity, temperature, skin friction, and heat transfer rates for a selection of parameter sets consisting of the viscosity parameter, magnetic field parameter, and Prandtl number are discussed. In order to validate our numerical results, the present results are compared with the available work in the literature and are found to be in an excellent agreement. 相似文献
45.
Vignesh Palani Melecio A. Perea Kristen E. Gardner Richmond Sarpong 《Chemical science》2021,12(4):1528
The synthesis of diverse N-fused heterocycles, including the pyrido[1,2-a]indole scaffold, using an efficient pyrone remodeling strategy is described. The pyrido[1,2-a]indole core was demonstrated to be a versatile scaffold that can be site-selectively functionalized. The utility of this novel annulation strategy was showcased in a concise formal synthesis of three fascaplysin congeners.The synthesis of diverse N-fused heterocycles, including the pyrido[1,2-a]indole scaffold, using an efficient pyrone remodeling strategy is described. 相似文献
46.
Chandrasekhar V Sasikumar P Boomishankar R 《Dalton transactions (Cambridge, England : 2003)》2008,(38):5189-5196
The reaction of ArPO(3)H(2) (Ar = 2,4,6-iPr(3)-C(6)H(2)) with Cd(CH(3)COO)(2).2H(2)O using various co-ligands such as methanol, dimethylformamide (DMF) and 3,5-dimethylpyrazole (DMPZH) resulted in the formation of tetranuclear assemblies [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(CH(3)OH)(4)].3(CH(3)OH) (1), [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(DMF)(4)].3(DMF) (2) and [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(DMF)(2)(DMPZH)(2)].2(DMF).2(H(2)O) (3). In all of these compounds the tetranuclear cadmium array, containing two five-coordinate and two six-coordinate cadmium atoms, is held together by two mu(4) capping [ArPO(3)](2-) and four anisobidentate mu(2) [ArPO(2)(OH)](-) ligands. Each cadmium atom is bound to an additional ancillary ligand. The reaction of ArPO(3)H(2) with Cd(CH(3)COO)(2).2H(2)O in the presence of the chelating ligand 2,2'-bipyridine (bipy) leads to the exclusive formation of the dinuclear assembly [Cd(2)(ArPO(3)H)(4)(bipy)(2)].(CH(3)OH)(H(2)O) (4). The latter contains an eight-membered Cd(2)P(2)O(4) inorganic ring formed as a result of the bridging coordination action of two anisobidentate mu(2) [ArPO(2)(OH)](-) ligands. Each cadmium atom is bound by one chelating bipy and one monodentate [ArPO(2)(OH)](-) ligands. Use of four equivalents of 3,5-dimethylpyrazole leads to the formation of the mononuclear derivative [Cd(ArPO(3)H)(2)(DMPZH)(4)] (5). The molecular structure of the latter comprises of a central cadmium atom surrounded by six monodentate ligands. Four of these are neutral pyrazole ligands that occupy the equatorial plane; the remaining two are anionic phosphinate ligands which are present trans to each other. The thermal analysis of 1 and 4 reveals that the char residue obtained at 600 degrees C consists predominantly of Cd(2)P(2)O(7). 相似文献
47.
Xianhai Huang Nicolas Zorn Anandan Palani Robert Aslanian 《Tetrahedron letters》2012,53(52):7154-7158
A highly regioselective synthesis of N3-, N5-, and N7-substituted pyrimidopyrimidinetetraones is reported. The synthesis of N5-monosubstituted and N5-, N7-disubstituted compounds was achieved through selective alkylation and urea mediated pyrimidinedione formation reactions. For the more synthetically challenging N3-, N5-, and N7-trisubstituted structures, in combination with computational studies, a palladium catalyzed cascade reaction was successfully employed for the simultaneous formation of the pyrimidinedione ring and functionalization of the N3 position, which provided the trisubstituted products in high yields with full control of regioselectivity. By applying this methodology, key intermediate 26 was prepared in a few synthetic steps in good overall yield for further functionalization and quick SAR development. 相似文献
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49.
Palani TheerthagiriAppaswami Lalitha 《Tetrahedron letters》2012,53(41):5535-5538
This work demonstrates an efficient method to prepare α-aryl nitriles by direct cyanation of benzylic alcohol with TMSCN in the presence of a catalytic amount of Zn(OTf)2 under heating condition. A variety of benzylic alcohols can be converted into the corresponding α-aryl nitriles in good to excellent yields. 相似文献
50.
Sandeep Nadella Dr. Paulraj M. Selvakumar Dr. Eringathodi Suresh Dr. Palani S. Subramanian Prof. Dr. Markus Albrecht Dr. Michael Giese Dr. Roland Fröhlich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(52):16784-16792
Phenanthroline‐based hexadentate ligands L1 and L2 bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as LaIII, EuIII, TbIII, LuIII, and YIII metal ions, were synthesized, and the crystal structures of [ML1Cl3] (M=LaIII, EuIII, TbIII, LuIII, or YIII) complexes were determined. Solvent or water molecules act as coligands for the rare‐earth metals in addition to halide anions. The big LnIII ion exhibits a coordination number (CN) of 10, whereas the corresponding EuIII, TbIII, LuIII, and YIII centers with smaller ionic radii show CN=9. Complexes of L2, namely [ML2Cl3] (M=EuIII, TbIII, LuIII, or YIII) ions could also be prepared. Only the complex of EuIII showed red luminescence, whereas all the others were nonluminescent. The emission properties of the Eu derivative can be applied as a photophysical signal for sensing various anions. The addition of phosphate anions leads to a unique change in the luminescence behavior. As a case study, the quenching behavior of adenosine‐5′‐triphosphate (ATP) was investigated at physiological pH value in an aqueous solvent. A specificity of the sensor for ATP relative to adenosine‐5′‐diphosphate (ADP) and adenosine‐5′‐monophosphate (AMP) was found. 31P NMR spectroscopic studies revealed the formation of a [EuL2(ATP)] coordination species. 相似文献