New Q membrane scale-down model for process-scale antibody purification

Process-scale antibody production requires polishing steps with extremely high product throughput and robust operation. In this communication, the Sartobind Q membrane adsorber for process-scale antibody production is evaluated as an alternative to Q column chromatography. Although the capacity seen with large-scale membrane adsorbers is competitive with column chromatography, the same throughput is not achieved with the current scale-down models. The operational issues currently found in membrane scale-down models, including backpressure, which significantly compromises the membrane's capacity, were examined. A new scale-down model was designed to mimic the liquid flow path found in the large-scale capsule, and a new process capacity equivalent at both small and large scale was successfully achieved. Results of a 4-model virus study with a redesigned Sartobind Q absorber scale-down model at the new process capacity are presented.     

Low temperature nuclear orientation studies of the magnetic structures of RNiAl4 in applied magnetic fields

The accumulation of iron and arsenic from aqueous solution by lettuce leaves biomass was investigated using Mössbauer and EXAFS spectroscopic techniques. Mössbauer spectroscopy results show that iron is oxidized during sorption while EXAFS results indicate that iron is coordinated by approximately 6 oxygen and 2 carbon atoms while arsenic is coordinated by approximately 4 oxygen atoms with iron as a second neighbor.     

Application of a recyclable pseudoephedrine resin in asymmetric alkylations on solid phase

A pseudoephedrine resin has been successfully employed in asymmetric alkylations on solid phase. Immobilized pseudoephedrine amides are conveniently prepared by the one-step attachment of pseudoephedrine to Merrifield resin through the hydroxyl group and subsequent acylation on nitrogen. Deprotonation and alkylation of the resin-bound amides proceeds smoothly. Ketones and alcohols are cleaved from the resin in high enantiomeric excess and moderate to good overall yield. The parallel, asymmetric solid-phase synthesis of a small library of chiral ketones and alcohols has been carried out to illustrate the utility of the approach. Finally, the pseudoephedrine resin can be conveniently recycled and utilized with no significant loss in the yield or enantiomeric excess of the products.     

Development of a solid-phase 'asymmetric resin-capture-release' process: application of an ephedrine chiral resin in an approach to gamma-butyrolactones

The potential of a solid-phase asymmetric resin-capture-release strategy for high-throughput synthesis has been evaluated. Fukuzawa's Sm(ii)-mediated, asymmetric approach to gamma-butyrolactones was selected to illustrate the feasibility of such a process. Alpha,beta-unsaturated esters immobilised on an ephedrine chiral resin have been applied in an asymmetric approach to gamma-butyrolactones. Lactone products are obtained in moderate isolated yields with selectivities up to 96% ee. In addition, we have shown that the ephedrine resin can be conveniently recovered and recycled although in some cases lower yields were obtained on reuse of the chiral resin. A short synthesis of a moderate DNA-binding microbial metabolite using asymmetric resin-capture-release is also described.     

Metastable one-dimensional AgCl(1)-(x)I(x) solid-solution wurzite "tunnel" crystals formed within single-walled carbon nanotubes

High-resolution transmission electron microscopy and spatially resolved electron loss spectroscopy have revealed that a eutectic mixture of AgCl and AgI crystallizes within single walled carbon nanotubes (SWNTs) as metastable AgCl(1-)(x)I(x) 1D solid solution crystals. The incorporated halide crystals form wurzite "tunnel" structures with locally varying Cl:I ratios and reduced Ag coordination.     

Homogeneity of Lanthanide Doped Ceria Nanocrystal Dispersions Using High-resolution Transmission Electron Microscopy

Aqueous sols of crystalline solid solutions of the general formula Ce_1-xLn_xO_2-x/2x/2 [Ln = entire lanthanide range, x = 0–0.50 and square = anion vacancy] were synthesised using inorganic materials. The nanocrystals were dispersed on an amorphous silica support and individual crystals examined for composition and structure by high-resolution transmission electron microscopy (HREM) and energy dispersive analysis of X-rays (EDX). High-resolution pictures showed the nanocrystals to be mainly between 5 and 10 nm in size, rarely elongated and with atomically clean faceted surfaces.Diffractograms were used to measure the lattice parameters of the face-centre-cubic (fcc) fluorite structures giving values, depending on dopant species and concentration of dopant, in the range 5.5–5.8 Å. EDX analysis of individual crystals with the same nominal composition compared closely to each other and to that of an average over a large area indicating good homogeneity from the preparation method.     

Nuclear Orientation Studies of Magnetism in Single Crystal Pr0.5Nd0.5Ni

The angular distributions of -rays from ¹⁴²Pr, ¹⁴⁷Nd and ¹⁴⁴Pm in Pr_0.5Nd_0.5Ni were investigated by means of low-temperature nuclear orientation. The results show that the Pr and Nd electronic moments order along the c- and a-axis, respectively. Pm ions introduced as a very dilute magnetic impurity, preferentially align with the Nd ions.     

Direct sample fraction deposition using electrospray in narrow-bore size-exclusion chromatography/matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for polymer characterization

A direct sample fraction deposition method was developed for off-line size-exclusion chromatography (SEC)/matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. By using electrospray, the SEC eluent, together with a suitable matrix solution added coaxially, was directly deposited on the MALDI plate. Owing to the formation of very small droplets in electrospray, solvent evaporation is much faster. The fractionation volume in narrow-bore SEC, which can directly be collected in one MALDI spot, can easily be optimized in the range of a few microlitres. In addition, fairly homogeneous sample spots were obtained. The possible influence of composition variation of the SEC effluent on the analytical results using direct fraction deposition was investigated; no substantial effects were observed. The applicability of the method was demonstrated by characterizing a broad poly(methyl methacrylate) sample. Copyright 2000 John Wiley & Sons, Ltd.     

Application of an ephedrine chiral linker in a solid-phase, 'asymmetric catch-release' approach to gamma-butyrolactones

A Sm(II)-mediated, asymmetric, intermolecular ketyl-olefin addition employing alpha,beta-unsaturated esters linked to resin through an ephedrine 'chiral link' has been applied in a direct 'asymmetric catch-release' approach to gamma-butyrolactones.     

Structural, photonic band-gap, and luminescence properties of the opal-erbium composite

Erbium oxide and silicates were embedded in the pores of synthetic opal by using the chemical bath deposition technique. Electron-microscopic images showed the synthesized compounds to be deposited predominantly in a thin uniform layer on the inner surface of the pores. An analysis of the transmittance spectra suggested that the opal-erbium composite thus obtained retained the photonic band-gap properties of the original ordered opal matrix. The Er³⁺ ions in the composite emitted light at several wavelengths in the visible and near-IR regions (550, 860, 980, 1240, 1530 nm) at 80 K.