Low-temperature solubility of copper in iron: experimental study using thermoelectric power,small angle X-ray scattering and tomographic atom probe

Measuring the solubility limit of copper in iron at temperature lower than 700°C is problematic because copper diffusion is too slow in this temperature range. To overcome this difficulty, fine precipitation of copper is studied. The solubility limit of copper is measured after complete precipitation using two complementary techniques: thermoelectric power and small angle X-ray scattering. Values obtained are confirmed by tomographic atom probe and give results much higher than what is usually extrapolated from high-temperature experiments.     

Encounter at far point

This column is a place for those bits of contagious mathematics that travel from person to person in the community, because they are so elegant, suprising, or appealing that one has an urge to pass them on. Contributions are most welcome.     

Electronic Olfactory Sensor Based on A. mellifera Odorant‐Binding Protein 14 on a Reduced Graphene Oxide Field‐Effect Transistor

An olfactory biosensor based on a reduced graphene oxide (rGO) field‐effect transistor (FET), functionalized by the odorant‐binding protein 14 (OBP14) from the honey bee (Apis mellifera) has been designed for the in situ and real‐time monitoring of a broad spectrum of odorants in aqueous solutions known to be attractants for bees. The electrical measurements of the binding of all tested odorants are shown to follow the Langmuir model for ligand–receptor interactions. The results demonstrate that OBP14 is able to bind odorants even after immobilization on rGO and can discriminate between ligands binding within a range of dissociation constants from K_d=4 μM to K_d=3.3 mM . The strongest ligands, such as homovanillic acid, eugenol, and methyl vanillate all contain a hydroxy group which is apparently important for the strong interaction with the protein.     

Interactions between lipopolysaccharide and outer membrane proteins of Acinetobacter calcoaceticus studied by an affinity electrophoresis system

R-Form lipopolysaccharides of Acinetobacter calcoaceticus could be incorporated into polyacrylamide gels in an immobile form by adding it directly to the acrylamide-N,N'-methylenebisacrylamide polymerization mixture. The separation of A. calcoaceticus 69 V outer membrane proteins in these affinity gels demonstrated a specific interaction with the lipopolysaccharide ligand for one of the proteins. This protein is heat-modifiable and has an Mr of about 18,000. By incorporation of varying concentrations of lipopolysaccharide, a dissociation constant of the protein-lipopolysaccharide complex of 0.5 mM could be determined. In comparison, for another A. calcoaceticus strain, CCM 5593, a higher dissociation constant (1.0 mM)--indicative of lower affinity--was obtained.     

Inventory control in dual sourcing commodity procurement with price correlation

Central European Journal of Operations Research - In this paper, we focus on the role of inventory management as a means for operational hedging by dual sourcing of commodities using a multi-period...     

TOF-SIMS investigations on weathered silver surfaces

Silver-coated quartz crystal microbalance (QCM) disks were treated under different environmental conditions (including changes in parameters such as relative humidity (%RH) and SO₂/H₂S content) in atmospheres of synthetic air and pure N₂ for 24 h in a weathering chamber. The corroded surfaces were subjected to depth profiling by a time of flight (TOF) secondary ion mass spectrometry (SIMS) instrument, equipped with a Bi⁺ analysis gun and Cs⁺ sputter gun. The evaluation of the in-depth distribution of several elements and species provides evidence for the formation of a corrosion layer containing Ag₂SO₃, even in the absence of oxidizing agents, such as H₂O₂ or NO₂. Furthermore it could be elucidated that the thickness of the formed Ag₂SO₃ layer does not depend on the SO₂ concentration but rather on the humidity and oxygen content of the ambient atmosphere. In weathering experiments in atmospheres composed of synthetic air, humidity, and H₂S, the presence of different oxygen species (surface and bulk) and silver sulfide could be detected by TOF-SIMS depth profiling experiments. The obtained results for both acidifying gases are in good correlation with the corresponding tapping mode atomic force microscopy (TM-AFM) investigations and in situ QCM measurements.