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71.
An economic evaluation of a chromatographic separation is discussed. The effects of particle size, cycle time, solvent, and column costs are analyzed. With small particles (<20 µm), the cost of the packing can be as much as 99% of the total cost of the process, whereas with large particles (>60 µm), resin costs are less than half of the total. A strong optimum is found between 20–40 µm for maximum productivity, using both Gaussian models and the mass transfer model of Lapidus and Amundson to generate peaks. A new compilation of resin costs, column costs, and pump costs is given.
相似文献72.
73.
In this paper we extend to the case of multiply connected regions the famous result of Sarason concerning the characterization of operators commuting with the compression of the unilateral shift on to a co-invariant subspace.
74.
A. Cornia A. C. Fabretti G. Gavioli C. Zucchi M. Pizzotti A. Vizi-Orosz O. I. Shchegolikhina Yu. A. Pozdniakova G. Pályi 《Journal of Cluster Science》1998,9(3):295-319
The heterobimetallic cyclosiloxanolate sandwich clusters Na[6-cyclo (PhSiO2)6]2[Fe(OR)]2Ni4(6-Cl) (R = H, Me) (1) were prepared from Na2[(PhSiO2)6]2Na4Ni4(OH)2 in the form of solvates. The new clusters 1 were characterized by spectra (UV-VIS, IR, 1H-NMR), cyclic voltammetry. conductivity, magnetic susceptibility, and single-crystal X-ray diffraction. 相似文献
75.
76.
Adele Cutignano 《Tetrahedron letters》2004,45(12):2627-2629
The paper reports the biosynthesis of the main alkylpyridine alkaloids, haminol-1 (1) and -2 (2), in the Mediterranean mollusc Haminoea orbignyana. Experiments were carried out by in vivo incorporation of [1,2- 13C2 acetate]. Data give full account for a polyketide origin of haminols in the Mediterranean molluscs, showing the biosynthesis of these 3-alkylpyridine alkaloids by elongation with acetate of a starter unit of nicotinic acid. 相似文献
77.
To characterize ultrafiltration membranes, it is important to understand their intrinsic, macromolecular-rejection properties. Defining these properties in terms of a membrane's permselectivity parameters requires an understanding of the mass transfer of the solute at the membrane interface. The solute concentration is difficult to measure experimentally, and has been previously estimated using various forms of a mass transfer coefficient. In this paper, we present an analytical, steady-state model for predicting ultrafiltration solute concentrations at the membrane interface from experimentally measured parameters and known solute physical properties - without the use of a mass transfer correlation. We then extend the model by looking at mass transfer through the membrane itself, in order to predict membrane permselectivity parameters. 相似文献
78.
Cecilia Mortalò Andrea Caneschi Andrea Cornia Eliano Diana Silvia Faranda Valérie Marvaud Maddalena Pizzotti Olga I. Shchegolikhina Claudia Zucchi Gyula Pályi 《Journal of Cluster Science》2007,18(1):217-236
New cyclosiloxanolate transition metal cluster complex derivatives were prepared. PhSiO2K reacted with NiX2 (X2 = Cl2 or acac) to give K2{[η6−(PhSiO2)6]2[μ3−(OH)]2Ni4K4}, a mixed group 1–group 10 metal complex. PhSiO2Na reacted with Ni(NH3)6I2 to give Na{[η6−(PhSiO2)6]2Ni6(μ6−I)} as the first example of “encapsulated” I− ion in siloxanolate complexes. The macrocyclic Na4{[η12−(PhSiO2)12]Cu4} complex reacted with η6−(1,3,5−C7H8)Cr(CO)3 to give the heterobimetallic adduct Na4{[η12−(PhSiO2)12]Cu4}· [Cr(CO)3]3 as one of the rare examples of heterobimetallic complexes with different oxidation numbers of the metals. The copper derivative
{[η6−(PhSiO2)6]2Cu6(n−BuOH)5} reacted in MeOH/CHCl3 (1:6) with Et4NCN to give the hexanuclear complex {[η6−(PhSiO2)6]2Cu6(η2−C3H5N2O2)2}, containing 2-amino-2-oxoetanimidic acid methyl ester monoanion ligands, product of an unexpected C–C coupling reaction.
This latter complex was characterized also by X-ray diffraction crystal and molecular structure determination.
This paper is dedicated to the 70th birthday of Professor Dr. Gunter Schmid (Essen), pioneer of large cluster chemistry, known
to friends as GOLD-Schmid, because of his famous discovery of the Au55 cluster. The Authors are proud to be within his many friends. 相似文献
79.
80.
Adele Mucci Luisa Schenetti Maria A. Vandelli Barbara Ruozi Gianfranco Salvioli Flavio Forni 《Supramolecular chemistry》2013,25(4):427-433
Abstract The formation and geometry of the hyodeoxycholic acid (HDCA)/2-hydroxypropyl-β-cyclodextrin (HPβCD) complex in methanol-d4 solution was determined through a rotating frame nuclear Overhauser (ROESY) experiment. The reported results confirmed those independently and previously obtained though the use of 13C complexation shifts in the same solvent. The 13C approach, which needs shorter experimental times and is currently used in the study of HPβCD/bile acid systems, was then substantiated. 相似文献