Optimization of large-scale chromatography for biotechnological applications

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.

     

Generalized interpolation in a multiply connected region

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.

     

Heterobimetallic Cyclosiloxanolate Sandwich Clusters: Na[η6-cyclo(PhSiO2)6]2[Fe(OR)]2Ni4(μ6-Cl) (R = H, Me)

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.     

Polyketide origin of 3-alkylpyridines in the marine mollusc Haminoea orbignyana

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.     

Three layer membrane model for characterizing ultrafiltration membranes

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.     

New Cyclosiloxanolate Cluster Complexes of Transition Metals

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.     

Comparison between Roesy and 13C NMR Complexation Shifts in Deriving the Geometry of Inclusion Compounds: A Study on the Interaction between Hyodeoxycholic Acid and 2-Hydroxypropyl-β-Cyclodextrin

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.