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Lipid bilayers were deposited inside the 0.2 μm pores of anodic aluminum oxide (AAO) filters by extrusion of multilamellar liposomes and their properties studied by ²H, ³¹P, and ¹H solid-state NMR. Only the first bilayer adhered strongly to the inner surface of the pores. Additional layers were washed out easily by a flow of water as demonstrated by ¹H magic angle spinning NMR experiments with addition of Pr³⁺ ions to shift accessible lipid headgroup resonances. A 13 mm diameter Anopore filter of 60 μm thickness oriented approximately 2.5 × 10^-7 mol of lipid as a single bilayer, corresponding to a total membrane area of about 500 cm². The ²H NMR spectra of chain deuterated POPC are consistent with adsorption of wavy, tubular bilayers to the inner pore surface. By NMR diffusion experiments, we determined the average length of those lipid tubules to be approximately 0.4 μm. There is evidence for a thick water layer between lipid tubules and the pore surface. The ends of tubules are well sealed against the pore such that Pr³⁺ ions cannot penetrate into the water underneath the bilayers. We successfully trapped poly(ethylene glycol) (PEG) with a molecular weight of 8000 in this water layer. From the quantity of trapped PEG, we calculated an average water layer thickness of 3 nm. Lipid order parameters and motional properties are unperturbed by the solid support, in agreement with existence of a water layer. Such unperturbed, solid supported membranes are ideal for incorporation of membrane-spanning proteins with large intra- and extracellular domains. The experiments suggest the promise of such porous filters as membrane support in biosensors.

The absorption spectra of I2 and Br2 dissolved in n-heptane and CCl4 are recorded with high precision in the visible-near-IR spectral range, at temperatures between 15° and 50 °C. The spectra are decomposed into the three contributing transitions (¹Πu ← X, B0⁺u³Π ← X, and A 1u³Π ← X) through simultaneous least-squares fitting of the T-dependent data. The main results of the analysis are as follows. (1) In I2 the weakest A ← X band is virtually identical in shape and intensity in these solvents and in the gas phase, but with small blue shifts in solution. (2) The ~20% increased absorption of I2 in solution appears to be largely attributable to a doubling in the intensity of the weaker of the two main transitions, ¹Πu ← X, which is red-shifted in solution. (3) All three transitions in I2 shift to the red with increasing T, with the strongest effect observed for ¹Πu ← X. These differences are not explained by the refraction-index-based relations commonly used to relate gas- and condensed-phase spectra. In the course of this work the method of decomposition analysis by fitting to assumed band shapes has been tested extensively, with the following observations. (1) The much-used 3-parameter Gaussian and log-normal functions do not have enough flexibility to fit single “pure” bands within the experimental precision obtainable from commercial spectrophotometers. (2) The results of such analyses can vary widely with choice of band function. (3) When comparing two such analyses, lower variance is no guarantee of a “truer” resolution. Concerning the labeling of the halogen electronic states involved in the absorption, it is recommended that for consistency the ¹Πu state be designated as the C state in all the halogens.

AbstractThe paper begins by looking at the ‘context of practice’: the programmes of the SRCD are briefly described and even more briefly the dominant (global) socio-economic trends as they impact on ours and other tertiary institutions. Because it is important in order to make sense of the programme we then attempt to provide a detailed profile of our students.The central questions with which we grapple, viz., the problems encountered in the curriculum activities designed to enable students to gain competence in ‘soft’ systems thinking and learning to learn, are dealt with in the sections ‘The Programme’, ‘The Results’ and ‘Bad practice, bad theory, or both’. In the first of these we give a very brief overview of Kolb's learning theory and Checkland's SSM and then show how the two can be (theoretically) integrated — Checkland's learning system is embedded in Kolb's learning cycle (LC). In the next section we report on an evaluation of the programme from the student's perspective. And then, finally, we discuss the shortcomings of Kolb's theory in our context as well as our use of Checkland's SSM. Our critique of Kolb is central to the entire endeavour, because his theory of experiential learning provides the theoretical underpinning of our curriculum development endeavour.In the final section we make some suggestions for a way forward based on our critique.