Testing the Underlying Chemical Principles of the Biotic Ligand Model (BLM) to Marine Copper Systems: Measuring Copper Speciation Using Fluorescence Quenching

Speciation of copper in marine systems strongly influences the ability of copper to cause toxicity. Natural organic matter (NOM) contains many binding sites which provides a protective effect on copper toxicity. The purpose of this study was to characterize copper binding with NOM using fluorescence quenching techniques. Fluorescence quenching of NOM with copper was performed on nine sea water samples. The resulting stability con- stants and binding capacities were consistent with literature values of marine NOM, show- ing strong binding with log K values from 7.64 to 10.2 and binding capacities ranging from 15 to 3110 nmole mg C −1 . Free copper concentrations estimated at total dissolved copper concentrations corresponding to previously published rotifer effect concentrations, in the same nine samples, were statistically the same as the range of free copper calculated for the effect concentration in NOM-free artificial seawater. These data confirms the applicability of fluorescence spectroscopy techniques for NOM and copper speciation characterization in sea water and demonstrates that such measured speciation is consistent with the chemical principles underlying the Biotic Ligand Model (BLM) approach for bioavailability-based metals risk assessment

Normal exploitation, normal resistance

En este texto, James C. Scott desarrolla el concepto de “formas cotidianas de resistencia”. Mientras los estudios sobre las resistencias campesinas anteriores se han centrado especialmente en analizar las rebeliones violentas y organizadas, Scott trata de demostrar que éstas han sido formas minoritarias y menos prácticas de resistencia, y que los campesinos han desarrollado su resistencia principalmente por medio de las prácticas del día a día, en ocasiones de forma oculta y en cualquier caso no llamativa. Para ello, da una especial importancia no sólo a los actos, sino también a la experiencia y la conciencia de los agentes de la resistencia, entrando así en diálogo con conceptos como “la hegemonía” de Gramsci y con las corrientes más estructuralistas del marxismoIn this text, James C. Scott develops the concept “everyday forms of resistance”. Whereas former studies about peasant resistances have focused specially in violent and organized rebellions, Scott tries to prove how these forms of rebellion have been a minority and unpractical form of resistance. Instead, peasants have developed their resistance mainly through everyday practices, sometimes in a hidden way, and in any case not in a noteworthy way. For this purpose, he places emphasis not only in the acts, but also in the experience and consciousness of resistant agents and, by doing so, he enters into dialogue with concepts like Gramci’s “hegemony” and with the most structuralist Marxist school

Why the median-priced home costs so much

Housing - Prices

New Insights on Liquid Impact and Dispersion

Sandia National Laboratories is interested in high speed, large liquid slug impact and dispersion in support of vulnerability assessment for fuel ignition and combustion. There is no previous research done in this area because prior work has focused on relatively small-Weber-number (We \u3c 104) impacts meant for regimes related to processes such as ink jet printing, material coatings, and internal combustion. Our experimental and model simulation results for high Weber number impacts (up to 108) have provided valuable information on high-speed fuel impact and dispersion as well as new insights for droplet impacts for all regimes. This new insight has also led the research to re-visit and include applications regarding processes for low Weber-number droplet impact. Sandia is a Department of Energy National Nuclear Security Administration laboratory with strong research connections to the Department of Homeland Security. The laboratory has robust programs in materials science, combustion, reactive flow and transport, stockpile stewardship, and alternative energy to name a few. I will be available after the presentation to discuss Sandia’s aggressive hiring campaign planned for this fiscal year