Elucidating the Quenching Mechanism of Tris(2,2'-bipyridyl)ruthenium(II) Complex in the Water-Glycerol Binary System Based on the Microscopic Structure of the Media.

Kinetic studies on the photochemical quenching reaction of the tris(2,2'-bipyridyl) ruthenium(II) complex ([Ru(bpy)3]2+) in water-glycerol binary media were conducted based on the Einstein-Smoluchowski (E-S) theory. Dynamic and static quenching behaviors were analyzed by comparing results from time-resolved spectroscopy and emission spectroscopy. While the dynamic quenching reaction aligns well with the E-S theory, static quenching was observed, leading to a notable increase in the overall photoquenching reaction rate constant. Employing chromatography and infrared spectroscopy, we correlated the microscopic molecular structure of the binary solvent system and the solvation environment around the emitters with the reaction mechanism. This correlation was found to correspond to ion pair formation and the confinement effect of the emitter, respectively.

Efficient use of all ports of a 3 × 3 coupler in a nonlinear amplifying loop mirror-based fiber laser.

We present an all-polarization-maintaining mode-locked fiber laser based on a nonlinear amplifying loop mirror utilizing a 3 × 3 coupler. A pump laser diode placed outside the cavity pumps both the oscillator and fiber amplifier. This laser configuration effectively utilizes all ports of the coupler, making the laser compact and low-cost, and has great potential as a seed laser for ultrashort pulse lasers.

Semi-local machine-learned kinetic energy density functional with third-order gradients of electron density.

A semi-local kinetic energy density functional (KEDF) was constructed based on machine learning (ML). The present scheme adopts electron densities and their gradients up to third-order as the explanatory variables for ML and the Kohn-Sham (KS) kinetic energy density as the response variable in atoms and molecules. Numerical assessments of the present scheme were performed in atomic and molecular systems, including first- and second-period elements. The results of 37 conventional KEDFs with explicit formulae were also compared with those of the ML KEDF with an implicit formula. The inclusion of the higher order gradients reduces the deviation of the total kinetic energies from the KS calculations in a stepwise manner. Furthermore, our scheme with the third-order gradient resulted in the closest kinetic energies to the KS calculations out of the presented functionals.

Construction of T-Motif-Based DNA Nanostructures through Enzymatic Reactions.

The most common way to fabricate DNA nanostructures is to mix individually synthesized DNA oligomers in one pot. However, if DNA nanostructures could be produced through enzymatic reactions, they could be applied in various environments, including in vivo. Herein, an enzymatic method developed to construct a DNA nanostructure from a simple motif called a T-motif is reported. A long, repeated structure was replicated from a circular template by rolling circle amplification and then cleaved into T-motif segments by restriction enzymes. These motifs have been successfully assembled into a ladder-like nanostructure without purification or controlled annealing. This approach is widely applicable to constructing a variety of DNA nanostructures through enzymatic reactions.