An Optical Trap Combined with Three-Color FRET

We developed a hybrid technique combining optical tweezers and single-molecule three-color fluorescence resonance energy transfer (FRET). In demonstrative experiments, we observed the force-sensitive correlated motion of three helical arms of a Holliday junction and identified the independent unfolding/folding dynamics of two DNA hairpins of the same length. With 3 times the number of observable elements of single-molecule FRET, this new instrument will enable the measurement of the complex, multidimensional effects of mechanical forces in various biomolecular systems, such as RNA and proteins

Extraordinary Off-Stoichiometric Bismuth Telluride for Enhanced n‑Type Thermoelectric Power Factor

Thermoelectrics directly converts waste heat into electricity and is considered a promising means of sustainable energy generation. While most of the recent advances in the enhancement of the thermoelectric figure of merit (<i>ZT</i>) resulted from a decrease in lattice thermal conductivity by nanostructuring, there have been very few attempts to enhance electrical transport properties, i.e., the power factor. Here we use nanochemistry to stabilize bulk bismuth telluride (Bi₂Te₃) that violates phase equilibrium, namely, phase-pure n-type K_0.06Bi₂Te_3.18. Incorporated potassium and tellurium in Bi₂Te₃ far exceed their solubility limit, inducing simultaneous increase in the electrical conductivity and the Seebeck coefficient along with decrease in the thermal conductivity. Consequently, a high power factor of ∼43 μW cm^–1 K^–2 and a high <i>ZT</i> > 1.1 at 323 K are achieved. Our current synthetic method can be used to produce a new family of materials with novel physical and chemical characteristics for various applications