Faculty Recital: Geoffrey Duce and Jameson Cooper

Kemp Recital HallApril 11, 2016Monday Evening8:00 p.m

Development of a 3D printer using scanning projection stereolithography

We have developed a system for the rapid fabrication of low cost 3D devices and systems in the laboratory with micro-scale features yet cm-scale objects. Our system is inspired by maskless lithography, where a digital micromirror device (DMD) is used to project patterns with resolution up to 10 µm onto a layer of photoresist. Large area objects can be fabricated by stitching projected images over a 5cm2 area. The addition of a z-stage allows multiple layers to be stacked to create 3D objects, removing the need for any developing or etching steps but at the same time leading to true 3D devices which are robust, configurable and scalable. We demonstrate the applications of the system by printing a range of micro-scale objects as well as a fully functioning microfluidic droplet device and test its integrity by pumping dye through the channels

Taming combinatorial explosion of the formose reaction via recursion within mineral environments

One‐pot reactions of simple precursors, such as those found in the formose reaction or formamide condensation, continuously lead to combinatorial explosions in which simple building blocks capable of function exist, but are in insufficient concentration to self‐organize, adapt, and thus generate complexity. We set out to explore the effect of recursion on such complex mixtures by ‘seeding’ the product mixture into a fresh version of the reaction, with the inclusion of different mineral environments, over a number of reaction cycles. Through untargeted UPLC‐HRMS analysis of the mixtures we found that the overall number of products detected reduces as the number of cycles increases, as a result of recursively enhanced mineral environment selectivity, thus limiting the combinatorial explosion. This discovery demonstrates how the involvement of mineral surfaces with simple reactions could lead to the emergence of some building blocks found in RNA, Ribose and Uracil, under much simpler conditions that originally thought

Magnetic characterization of the frustrated three-leg ladder compound [(CuCl2tachH)3Cl]Cl2

We report the magnetic features of a new one-dimensional stack of antiferromagnetically coupled equilateral copper(II) triangles. High-field magnetization measurements show that the interaction between the copper triangles is of the same order of magnitude as the intra-triangle exchange although only coupled via hydrogen bonds. The infinite chain turns out to be an interesting example of a frustrated cylindrical three-leg ladder with competing intra- and inter-triangle interactions. We demonstrate that the ground state is a spin singlet which is gaped from the triplet excitation.Comment: 6 pages, 9 figures, revised version submitted to Phys. Rev. B. More information at http://obelix.physik.uni-osnabrueck.de/~schnack

Formation of oligopeptides in high yield under simple programmable conditions

Many high-yielding reactions for forming peptide bonds have been developed but these are complex, requiring activated amino-acid precursors and heterogeneous supports. Herein we demonstrate the programmable one-pot dehydration–hydration condensation of amino acids forming oligopeptide chains in around 50% yield. A digital recursive reactor system was developed to investigate this process, performing these reactions with control over parameters such as temperature, number of cycles, cycle duration, initial monomer concentration and initial pH. Glycine oligopeptides up to 20 amino acids long were formed with very high monomer-to-oligomer conversion, and the majority of these products comprised three amino acid residues or more. Having established the formation of glycine homo-oligopeptides, we then demonstrated the co-condensation of glycine with eight other amino acids (Ala, Asp, Glu, His, Lys, Pro, Thr and Val), incorporating a range of side-chain functionality

Investigations of carbon fibres and their precursor materials by E.S.R. and related techniques

The desirable mechanical properties that have lead to the manufacture of carbon fibre laminates for aerospace applications are developed in fibre heat treated in excess of 1000°C. The research group at Keele made an exhaustive study of these high temperature fibres by electron spin resonance (ESR) and other electronic techniques. However, we report here a similar investigation of the electronic processes in carbon fibre heat treated below 1000°C as established by ESR, electrical conductivity and thermoelectric power (TEP) measurements. We established that the g-value of the ESR spectrum was anisotropic indicating that even in the early stages of heat treatment the free spins are associated with layer planes which are preferentially aligned along the fibre axis. The results tend to indicate that excessive preoxidation hinders the structural development within these fibres. The electrical conduction takes place by a process of 'electron hopping* between localized sites beyond the nearest neighbour separation. This process of conduction implies a disordered structure, however we find that the result is not inconsistent with our model as the hopping appears to take place along two dimensional layer planes. The spin-lattice relaxation processes were also determined and it is evident that the spin system is not efficiently coupled to the lattice. In addition to the study of the thermal degradation of the precursor materials we also applied the ESR technique to a study of the free radicals produced in the precursors by mechanical degradation and by irradiation damage. Tentative assignment of the free radicals produced by irradiation damage was made

Three-dimensional simulations of a starburst wind

In order to better understand the formation of a starburst-driven wind, we have performed a series of three-dimensional hydrodynamical simulations in an inhomogeneous interstellar medium. We present the results of these simulations, which provide new insights into the formation of the optical filaments and the origin of the soft X-ray emission

Effects of etelcalcetide on fibroblast growth factor 23 in patients with secondary hyperparathyroidism receiving hemodialysis

Background: Etelcalcetide is an intravenous calcimimetic approved for treatment of secondary hyperparathyroidism (sHPT) in patients receiving hemodialysis. Besides lowering parathyroid hormone (PTH), etelcalcetide also significantly reduces fibroblast growth factor 23 (FGF23), but the mechanisms are unknown. Methods: To investigate potential mediators of etelcalcetide-induced FGF23 reduction, we performed secondary analyses of the 26-week randomized trials that compared the effects on PTH of etelcalcetide (n = 509) versus placebo (n = 514) and etelcalcetide (n = 340) versus cinacalcet (n = 343) in adults with sHPT receiving hemodialysis. We analyzed changes in FGF23 in relation to changes in PTH, calcium, phosphate and bone turnover markers. We also investigated how concomitant treatments aimed at mitigating hypocalcemia altered the FGF23-lowering effects of etelcalcetide. Results: Etelcalcetide reduced FGF23 [median % change (quartile 1-quartile 3)] from baseline to the end of the trial significantly more than placebo [-56% (-85 to -7) versus +2% (-40 to +65); P < 0.001] and cinacalcet [-68% (-87 to -26) versus -41% (-76 to +25); P < 0.001]. Reductions in FGF23 correlated strongly with reductions in calcium and phosphate, but not with PTH; correlations with bone turnover markers were inconsistent and of borderline significance. Increases in concomitant vitamin D administration partially attenuated the FGF23-lowering effect of etelcalcetide, but increased dialysate calcium concentration versus no increase and increased dose of calcium supplementation versus no increase did not attenuate the FGF23-lowering effects of etelcalcetide. Conclusion: These data suggest that etelcalcetide potently lowers FGF23 in patients with sHPT receiving hemodialysis and that the effect remains detectable among patients who receive concomitant treatments aimed at mitigating treatment-associated decreases in serum calcium