MEMBRANE DAMAGE IN UV-IRRADIATED LENSES

Abstract The purpose of this study was to investigate three possible causes of membrane damage following UV irradiation: photooxidation of membrane thiol (SH) groups, peroxidation of membrane lipids and inhibited synthesis of membrane proteins. Thiol loss was not observed. Thin-layer chromatography showed a four-fold increase in several primary lipid peroxidation products such as hydroperoxyl lipids in the epithelial membrane preparations isolated from irradiated lenses. The formation of new hydroxyl lipid bands not seen in control preparations was also observed in isolated membranes from irradiated lenses. Irradiation in the presence or absence of oxygen produced lipid peroxidation products. Aerobic irradiation produced small, but statistically significant increases in lipid hydroxyls and hydroperoxyls relative to controls. Repair of initial damage might be compromised by the observed 60% reduction in rate of protein synthesis measured in lens membranes following irradiation. Synthesis was affected by means other than depleted potassium or elevated calcium levels.     

Measures on infinite dimensional Grassmann manifolds

A 1-parameter family of quasi-invariant measures is presented. These measures are cylinder measures in graph coordinates. Their characteristic functions are represented as integrals relative to an infinite product measure. This is applied to the problem of determining the support properties of the measures. One of the measures can be used to define the unitary structure for the basic representation of the affine extension of the restricted unitary group.     

Building teachers’ expertise in understanding, assessing and developing children’s mathematical thinking: the power of task-based, one-to-one assessment interviews

In this paper, we outline the benefits to teachers’ expertise of the use of research-based, one-to-one assessment interviews in mathematics. Drawing upon our research and professional development work with teachers and students in primary and middle years in Australia and the research of others, we argue that the use of the interviews builds teacher expertise through enhancing teachers’ knowledge of individual and group understanding of mathematics, and also provides an understanding of typical learning paths in various mathematical domains. The use of such interviews also provides a model for teachers’ interactions and discussions with children, building both their pedagogical content knowledge and their subject matter knowledge.     

Memorable Experiences of a Science Field Trip

Potential immediate outcomes of a science field trip are the retention of knowledge associated with the program and an improved attitude toward the site visited during the trip. The length of associated memories regarding this experience are less clear. In an attempt to begin learning more about memorable experiences associated with a science field trip, a 1‐month and an 18‐month evaluation was conducted of elementary school students who had participated in an environmental science program at a community park in a midwestern city. Results of the evaluation found that students' memories were nonspecific and disassociated from information given by the field teacher. On the other hand, results from both tests yielded positive responses toward wanting to learn more about the subject matter and an interest in returning to the field trip site. This would indicate that, while not retaining specific objective‐oriented content, students did gain a positive reaction to returning that continued over the long‐term. Research related to memorable experiences is outlined, using a theory of long‐term memory developed by Tulving (1972) as a basic paradigm of correlation for the subsequent investigation.     

The geography problem for irreducible spin four-manifolds

We study the geography problem for smooth irreducible simply-connected spin four-manifolds. For a large class of homotopy types, we exhibit both symplectic and non-symplectic representatives. We also compute the Seiberg-Witten invariants of all the four-manifolds we construct.

     

A ceric ammonium nitrate based oxidative cleavage pathway for the asymmetric aldol adducts of oxadiazinones derived from (1R,2S)-N-p-methoxybenzylnorephedrine

An N₄-p-methoxybenzyloxadiazinone has been prepared from (1R,2S)-norephedrine through a process of reductive amination, N-nitrosation, reduction, and cyclization. The oxadiazinone was acylated and employed in the asymmetric aldol addition reaction with aromatic and aliphatic aldehydes to yield aldol adducts in isolated yields ranging from 54% to 90%. Selected aldol adducts were treated with ceric ammonium nitrate in aqueous acetonitrile to afford the desired β-hydroxycarboxylic acids through a tandem process of oxidative cleavage of the N₄-p-methoxybenzyl group and acidic hydrolysis of the N₃-acyl side chain. The β-hydroxycarboxylic acids were recovered in high diastereomeric purity as determined by 500 MHz ¹H NMR spectroscopy and the absolute configuration was confirmed by polarimetry. The chiral auxiliary unit, the 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-one (oxadiazinone), was converted into its corresponding 3,6-dihydro-2H-1,3,4-oxadiazin-2-one (oxadiazinone) through an oxidative pathway promoted by the ceric ammonium nitrate.     

Generation of a Low Flow Atmospheric Pressure Neon ICP

Abstract

A 27.12 MHz low flow (3 1/min), laminar flow, atmospheric pressure neon ICP has been generated. The forward power used is 500 W with a reflected power of less than 5 W. Using higher powers caused the plasma to either extinguish or form numerous filaments. The Hß line is used to determine an electron number density of 8 × 10¹³cm^?3. The N₂ ⁺(0, 0) and OH(0, 0) transitions did not readily emit. This fact, coupled with the low electron density and low input power, indicates a relatively cool plasma.     

Mechanical stability enhancement by pore size and connectivity control in colloidal crystals by layer-by-layer growth of oxide

Control of the pore size and connectivity of micro-sphere colloidal crystal lattices has been achieved by a layer-by-layer growth of silica using atmospheric pressure room temperature chemical vapour deposition of silica, a method which largely increases the mechanical stability of the lattice without disrupting its long range order.     

Small non-Arguesian lattices

Presented by R. McKenzie.