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The excited-state intramolecular proton transfer (ESIPT) reaction of two phenol-quinoline molecules (namely PQ-1 and PQ-2) were investigated using time-dependent density functional theory. The five-(six-) membered-ring carbocycle between the phenol and quinolone moieties in PQ-1 (PQ-2) actually causes a relatively loose (tight) hydrogen bond, which results in a small-barrier (barrier-less) on an excited-state potential energy surface with a slow (fast) ESIPT process with (without) involving the skeletal deformation motion up to the electronic excitation. The skeletal deformation motion that is induced from the largest vibronic excitation with low frequency can assist in decreasing the donor-acceptor distance and lowering the reaction barrier in the excited-state potential energy surface, and thus effectively enhance the ESIPT reaction for PQ-1. The Franck-Condon simulation indicated that the low-frequency mode with vibronic excitation 0 → 1' is an original source of the skeletal deformation vibration. The present simulation presents physical insights for phenol-quinoline molecules in which relatively tight or loose hydrogen bonds can influence the ESIPT reaction process with and without the assistance of the skeletal deformation motion.

The absorption and fluorescence spectra of 4-(3-methoxybenzylidene)-2-methyl-oxazalone (m-MeOBDI) dissolved in neutral, acidic, and basic solvent environments have been investigated and assigned by using Franck–Condon (FC) simulations at the quantum TDDFT level. Four different structures of m-MeOBDI in the ground and excited states are optimized and are found to be responsible for the observed absorption and fluorescence spectra. The (absorption) fluorescence of m-MeOBDI in pure methanol and neutral/basic methanol/water (1/9 vol) mixed solvent is found to arise from the (ground neutral N-I) excited neutral N-I* and cationic C-III* species, respectively. In acidic solvent, the absorption is found to arise from ground acidic C-II species, and the excited divalent cation DC-IV* is found to be formed in its excited state due to the excess H+ in the solution, and then it emits ∼560 nm fluorescence. FC simulations have also been employed to confirm our assignments as well as interpret the vibronic band profiles. As expected, the simulated emission spectrum of the divalent cationic species is in good agreement with the experimental observation. Therefore, within the present FC simulation, the observed absorption and fluorescence spectra have been reasonably interpreted and novel fluorescence mechanisms of m-MeOBDI in various pH solvent environments have been proposed.

There is a current view that myosin light chain kinase (MLCK) plays a critical role in endothelial permeability. To investigate the functions of MLCK in endothelial cells in vivo, we generated a mouse model in which MLCK was selectively deleted by crossing Mylk1 floxed mice with Tie2/cre transgenic mice. Knocking out Mylk1 from endothelial cells had no effect on the global phenotype of the mice, including body weight and blood pressure. Lipopolysaccharide (LPS)-mediated septic death was also not altered in the knockout (KO) mice. Consistently, LPS-induced inflammatory injury and the increase in microvascular permeability in the main organs, including the lung and the kidney, was not significantly attenuated in KO mice as compared with wild-type mice. However, the LPS-induced microvascular hyperpermeability of the esophagus and the eyeballs was attenuated in KO mice. We also found that the LPS-mediated increase in the number of caveolae in the endothelial cells of the esophagus was significantly reduced in KO mice. Our results do not support a role for endothelial cell MLCK in the pathogenesis of inflammatory diseases.

Spin-dependent transport through a quantum-dot (QD) ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR) as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively.PACS numbers

The functions of long smooth muscle myosin light chain kinase (L-MLCK), a molecule with multiple domains, are poorly understood. To examine the existence of further potentially functional domains in this molecule, we analyzed its amino acid sequence with a tango program and found a putative aggregation domain located at the 4Ig domain of the N-terminal extension. To verify its aggregation capability in vitro, expressible truncated L-MLCK variants driven by a cytomegalovirus promoter were transfected into cells. As anticipated, only the overexpression of the 4Ig fragment led to particle formation in Colon26 cells. These particles contained 4Ig polymers and actin. Analysis with detergents demonstrated that the particles shared features in common with aggregates. Thus, we conclude that the 4Ig domain has a potent aggregation ability. To further examine this aggregation domain in vivo, eight transgenic mouse lines expressing the 4Ig domain (4Ig lines) were generated. The results showed that the transgenic mice had typical aggregation in the thigh and diaphragm muscles. Histological examination showed that 7.70 +/- 1.86% of extensor digitorum longus myofibrils displayed aggregates with a 36.44% reduction in myofibril diameter, whereas 65.13 +/- 3.42% of diaphragm myofibrils displayed aggregates and the myofibril diameter was reduced by 43.08%. Electron microscopy examination suggested that the aggregates were deposited at the mitochondria, resulting in structural impairment. As a consequence, the oxygen consumption of mitochondria in the affected muscles was also reduced. Macrophenotypic analysis showed the presence of muscular degeneration characterized by a reduction in force development, faster fatigue, decreased myofibril diameters, and structural alterations. In summary, our study revealed the existence of a novel aggregation domain in L-MLCK and provided a direct link between L-MLCK and aggregation. The possible significance and mechanism underlying the aggregation-based pathological processes mediated by L-MLCK are also discussed.

Photoinduced oxidation process of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] is probed by using broadband transient grating technique. The results suggest that the damage of bonds in the side and main chains leads to the line shape variation and efficiency decreasing of luminescence in photoluminescence quenching, and their temporal evolution and damage rates are found to vary with molecular energy states.