Dissolved urate salts out calcium oxalate in undiluted human urine in vitro: implications for calcium oxalate stone genesis

Hyperuricosuria has long been documented as a predisposing factor to calcium oxalate (CaOx) stone pathogenesis. However, its mechanism is still without sound scientific foundation. Previously, we showed that hyperuricosuria, simulated by the addition of dissolved sodium urate, promotes the crystallization of CaOx. In the present study, we demonstrate that the urate's effect on the crystallization is attributable to its salting out CaOx from solution. Furthermore, analysis of urines revealed that their metastable limit decreased with increases in the product of the prevailing concentrations of calcium and urate: this has implications for CaOx stone genesis. We also outline anti-salting out strategies for future research for the prevention and/or treatment of CaOx calculi.     

Synthesis of chiral alkenyl epoxides: the sex pheromone of the elm spanworm Ennomus subsignaria (Hübner) (Lepidoptera: Geometridae)

The identification of the sex pheromone of the elm spanworm Ennomos subsignaria (Hübner), as the chiral alkenyl epoxide (6Z)-cis-9,10-epoxy-nonadecene has been accomplished. Both enantiomers of (6Z)-cis-9,10-epoxy-nonadecene have been synthesized via two routes. The key steps in the first route were to prepare both threo-epoxy tosylates and then to perform an alkylative rearrangement of these intermediates to obtain the target molecules. An alternative enantioenriched synthesis that took advantage of the Sharpless dihydroxylation reaction was developed so that a common starting material could be used to access both enantiomers. A field study and GC/EAD testing indicated that Z6-cis-9S,10R-epoxy-nonadecene was the sex pheromone of the elm spanworm E. subsignaria (Hübner).     

Vibrational spectroscopy and DFT calculations of N,N′‐dicyclohexylcarbodiimide

Infrared (IR) and Raman spectra were obtained for N,N′‐dicyclohexylcarbodiimide (DCC) in the solid state and in CHCl₃ solution. Structures and vibrational spectra of isolated, gas‐phase DCC molecules with C₂ and C_i symmetries, computed at the B3‐LYP/cc‐pVTZ level, show that the IR and Raman spectra provide convincing evidence for a C₂ structure in both the solid state and in CHCl₃ solution. Using a scaled quantum‐chemical force field, these density functional theory calculations have provided detailed assignments of the observed IR and Raman bands in terms of potential energy distributions. Comparison of solid‐state and solution spectra, together with a Raman study of the melting behaviour of DCC, revealed that no solid‐state effects were evident in the spectra. Copyright © 2010 John Wiley & Sons, Ltd.     

A dielectric model of self-assembled monolayer interfaces by capacitive spectroscopy

The presence of self-assembled monolayers at an electrode introduces capacitance and resistance contributions that can profoundly affect subsequently observed electronic characteristics. Despite the impact of this on any voltammetry, these contributions are not directly resolvable with any clarity by standard electrochemical means. A capacitive analysis of such interfaces (by capacitance spectroscopy), introduced here, enables a clean mapping of these features and additionally presents a means of studying layer polarizability and Cole-Cole relaxation effects. The resolved resistive term contributes directly to an intrinsic monolayer uncompensated resistance that has a linear dependence on the layer thickness. The dielectric model proposed is fully aligned with the classic Helmholtz plate capacitor model and additionally explains the inherently associated resistive features of molecular films.     

Exciton emission from forward-biased zinc selenide Schottky diodes

Exciton emission has been observed in the forward-biased electroluminesence of ZnSe Schottky diodes free of intentionally added luminescent centres. The emission has been studied from ≈ 95° K to room temperature and is attributed to the recombination of free excitons (zero-LO phonon line). No LO phonon side bands were observed. As with exciton photoluminescence in CdS the half-width of the emission line, although a linear function of temperature, is greater than that predicted by theory. At temperatures below ≈150°K pair emission was also observed.     

Design of a focal-plane array thermographic system for stress analysis

A state-of-the-art thermographic system has been developed based on a 512×512 focal-plane array thermal imager. The system, dubbed FAST (for focal-plane array for synchronous thermography) is able to deliver high-resolution full-field thermoelastic stress scans in minutes rather than hours. The paper itemizes the hardware components together with their functions.The digital signal processing required is described in detail as well as some of the problems encountered and how they were solved. Finally a thermoelastic image is displayed illustrating the capability of this system.Permission is granted toExperimental Mechanics to publish the paper on a nonexclusive one-time basis in the journal. This agreement is subject to the Commonwealth of Australia retaining Copyright of the paper, the author and source of the paper has been acknowledged. No meaningful changes have been made to the paper without the prior consent of the author.