Tricalcium silicate (C3S) hydration under high pressure at ambient and high temperature (200 °C)

The hydration of a tricalcium silicate paste at ambient temperature and at 200 °C under high pressure (up to 1000 bar) has been studied. Two high pressure cells have been used, one allows in-situ electrical conductivity measurements during hydration under high pressure. The hydration products were characterized by thermal analysis, X-ray diffraction and ²⁹Si NMR measurements. The pressure has a large kinetic effect on the hydration of a C₃S paste at room temperature. The pressure was seen to affect drastically the hydration of a C₃S paste at 200 °C and this study evidences the competition between the different high temperature phases during the hydration.     

Weibull analysis of stiffness and strength in bulk epoxy adhesives reinforced with particles

The mechanical and statistical behaviour of aerospace structural adhesives has been investigated by performing tensile tests on moulded samples and applying Weibull theory to results. Effects of loading rate, sample size and process parameters have been studied. The experimental design method has been employed in an attempt to extend the experimental results to other combinations of parameters. Three kinds of structural adhesive have been characterised, viz, Hysol^® EA9321, Hysol^® EA9394 and Hysol^® EA9395, which are particle reinforced epoxy adhesives, all of them containing voids with statistically distributed sizes (partially dependent on bonding technique). These highly heterogeneous, but natural, microstructures explain the dispersion of measured strength and Young’s modulus of the materials. These two quantities are demonstrated not to be correlated. With these results, simple fibre bundle theory is used to evaluate the mean value and variance of the failure stress of a bonded joint loaded in tension.     

Alina Szeminska.

Draws attention to the omission of Dr. Alina Szeminska's name from the English translation of The Child's Conception of Number. The book, published in French in 1941, was coauthored by Jean Piaget and Szeminska. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On-line dual microdialysis with ESI-MS for direct analysis of complex biological samples and microorganism lysates

A novel dual-microdialysis approach has been developed for fast and efficient fractionation and cleanup for ESI-MS and ESI MS/MS analyses of biological samples. A modified dynamic microdialyzer utilizing two mirror-image serpentine channels, which sandwich a regenerated cellulose membrane of selected molecular weight cutoff, serves as the first stage for the removal of high-molecular-weight components and cellular residue. The second stage employs a hollow microdialysis capillary to remove low-molecular-weight species (e.g., salts) which can degrade or preclude analysis ESI-MS. A protein mixture consisting of 30 microM bovine serum albumin (BSA), 4.0 microM cytochrome c, 2.3 microM ubiquitin, and 9.4 microM bradykinin in 0.5 M NaCl was used to evaluate the performance of this system. Essentially complete removal of both BSA and NaCl was achieved, resulting in high-quality mass spectra containing only the lower molecular weight proteins. After passing through the on-line dual-microdialysis system, a crude bacteria cell lysate yielded clean ESI-mass spectra in approximately 20 min. MS/MS of selected ions demonstrated abundant fragment ions and provided a second-dimension "fingerprint" of the complex cellular fraction. Preliminary application of this technique for direct characterization of microorganism lysates is presented.     

Cobalt speciation study in the cobalt-cysteine system by electrospray ionization mass spectrometry and anion-exchange chromatography inductively coupled plasma atomic emission spectrometry

This paper describes the ability of the combination of electrospray ionization mass spectrometry (ESI-MS) and anion-exchange chromatography coupled with inductively coupled plasma atomic emission spectrometry (AEC-ICP-AES) for cobalt speciation study in the binary cobalt-cysteine system. ESI-MS, allowing the identification and the characterization of the analytes, is used as a technique complementary to AEC-ICP-AES, providing elemental information on the separated species. The methods have been developed through the study of samples containing Co2+ and 1-fold to 5-fold molar ratios of cysteine over a pH range 2.5 to 11. In each case, cobalt-cysteine complexes were characterized by ESI-MS in negative ion mode. AEC-ICP-AES allowed further separation and detection of the cobalt species previously characterized. The strong influence of pH and ligand-to-metal ratios on the nature and stoichiometry of the species is demonstrated. For the first time, a direct experimental speciation diagram of cobalt species has been established owing to these analytical techniques. This work is a promising basis for the speciation analysis of cobalt, since a good knowledge of cobalt speciation is of prime importance to better understanding its fate in biological and environmental media.