Structurally and electronically driven uniaxial negative thermal expansion in BaIrO.

Negative thermal expansion is known to exist in a range of structure types but is extremely rare in hexagonal perovskites. Here we demonstrate that BaIrO displays negative linear thermal expansion in the direction of its face-shared IrO trimers, and apparent zero volume thermal expansion below 100 K. We present evidence that this anomalous thermal expansion is driven by an unusual form of rigid body phonon behaviour governed by the effective trimer valence state and therefore has structural and electronic components to the underlying mechanism.

Configurational entropy of ice XIX and its isotope effect.

Ice XIX is a partly hydrogen-ordered polymorph related to disordered ice VI, similar to ice XV. We here investigate the order-order-disorder sequence ice XIX→ice XV→ice VI based on calorimetry at ambient pressure both for DO and HO-ice XIX. From these data we extract configurational entropy differences between ice XIX, ice XV and ice VI.

Competitive Immunoassay in a Microfluidic Biochip for In-Field Detection of Abscisic Acid in Grapes.

Viticulture and associated products are an important part of the economy in many countries. However, biotic and abiotic stresses impact negatively the production of grapes and wine. Climate change is in many aspects increasing both these stresses.

Origin of Polarization in Bismuth Sodium Titanate-Based Ceramics.

The classical view of the structural changes that occur at the ferroelectric transition in perovskite-structured systems, such as BaTiO, is that polarization occurs due to the off-center displacement of the B-site cations. Here, we show that in the bismuth sodium titanate (BNT)-based composition 0.2(BaSrTiO)-0.