A simple polymer electrolyte membrane system for enrichment of low-level tritium (3H) in environmental water samples

Tritium (³H) is an essential tracer of the Earth's water cycle; yet widespread adoption of tritium in hydrologic studies remains a challenge because of analytical barriers to quantification and detection of ³H by electrolytic pre-concentration. Here, we propose a simple tritium electrolytic enrichment system based on the use of solid polymer electrolyte membranes (PEMs) that can be used to enrich ³H in 250–3000?mL environmental water samples to a 10-mL final volume. The IAEA PEM-³H system reported here can produce high enrichment factors (>70-fold) and, importantly, removes some of the deterrents to conventional ³H enrichments methods, including the use of toxic electrolysis and neutralization chemicals, spike standards, a complex electrolysis apparatus that requires extensive cooling and temperature controls, and improves precision by eliminating the need for tracking recovery gravimetrics. Preliminary results with varying operating conditions show ³H enrichments to 70-fold and higher are feasible, spanning a wide range of tritium activities from 5 to 150 TU with a precision of ～4.5?%. Further work is needed to quantify inter-sample memory and to establish lower ³H detection limits. The IAEA PEM-³H system is open source, with 3-D CAD and design files made freely available for adoption and improvement by others.     

Stereoselective Ketone Rearrangements with Hypervalent Iodine Reagents

The first stereoselective version of an iodine(III)‐mediated rearrangement of arylketones in the presence of orthoesters is described. The reaction products, α‐arylated esters, are very useful intermediates in the synthesis of bioactive compounds such as ibuprofen. With chiral lactic acid‐based iodine(III) reagents product selectivities of up to 73 % ee have been achieved.     

Liquid Bridges Between Balls: The Small Volume Instability

Stability for a liquid bridge between two solid balls is studied by cutting and scaling pieces of a standardized family of Delaunay surfaces. This theoretical framework is used to analyze the problem numerically.