Electrochemical Investigation of High-Performance Dye-Sensitized Solar Cells Based on Molybdenum for Preparation of Counter Electrode

In order to improve the photocurrent conversion efficiency of dye-sensitized solar cells (DSSCs), we studied an alternative conductor for the counter electrode and focused on molybdenum (Mo) instead of conventional fluorine-doped tin oxide (FTO). Because Mo has a similar work function to FTO for band alignment, better formability of platinum (Pt), and a low electric resistance, using a counter electrode made of Mo instead of FTO lead to the enhancement of the catalytic reaction of the redox couple, reduce the interior resistance of the DSSCs, and prevent energy-barrier formation. Using electrical measurements under a 1-sun condition (100 mW/cm(2), AM 1.5), we determined that the fill factor (FF) and photocurrent conversion efficiency (eta) of DSSCs with a Mo electrode were respectively improved by 7.75% and 5.59% with respect to those of DSSCs with an FTO electrode. Moreover, we have investigated the origin of the improved performance through surface morphology analyses such as scanning electron microscopy and electrochemical analyses including cyclic voltammetry and impedance spectroscopy

Psychological antecedents of youth versus adult participation: An examination based on the Sport Commitment Model

This study examined adult and youth Taekwondo (TKD) participants utilizing the Sport Commitment Model (SCM). In addition to direct effects predicting commitment, indirect effects of enjoyment as a mediating variable were examined. TKD participants (adult, n = 204; youth, n = 227) from four studios completed a questionnaire that included SCM variables (commitment, enjoyment, involvement alternatives, involvement opportunities, personal investments, social constraints, and social support). Structural equation modeling analysis compared age groups to assess similarities and differences. Similarities between age groups included involvement opportunities and personal investments being significant predictors of commitment while involvement alternatives were a significant detractor of commitment. Analysis of differences found that the social variables (i.e., social constraints and support) and enjoyment were significant predictors for youth only. This was the first study examining the SCM with both youth and adults participating in the same sport activity. Findings are discussed relative to theoretical and practical implications. 

Ambiguity-Aware Multi-Object Pose Optimization for Visually-Assisted Robot Manipulation

6D object pose estimation aims to infer the relative pose between the object and the camera using a single image or multiple images. Most works have focused on predicting the object pose without associated uncertainty under occlusion and structural ambiguity (symmetricity). However, these works demand prior information about shape attributes, and this condition is hardly satisfied in reality; even asymmetric objects may be symmetric under the viewpoint change. In addition, acquiring and fusing diverse sensor data is challenging when extending them to robotics applications. Tackling these limitations, we present an ambiguity-aware 6D object pose estimation network, PrimA6D++, as a generic uncertainty prediction method. The major challenges in pose estimation, such as occlusion and symmetry, can be handled in a generic manner based on the measured ambiguity of the prediction. Specifically, we devise a network to reconstruct the three rotation axis primitive images of a target object and predict the underlying uncertainty along each primitive axis. Leveraging the estimated uncertainty, we then optimize multi-object poses using visual measurements and camera poses by treating it as an object SLAM problem. The proposed method shows a significant performance improvement in T-LESS and YCB-Video datasets. We further demonstrate real-time scene recognition capability for visually-assisted robot manipulation. Our code and supplementary materials are available at https://github.com/rpmsnu/PrimA6D.Comment: IEEE Robotics and Automation Letter

Anytime computation of time-optimal off-road vehicle maneuvers using the RRT*

Incremental sampling-based motion planning algorithms such as the Rapidly-exploring Random Trees (RRTs) have been successful in efficiently solving computationally challenging motion planning problems involving complex dynamical systems. A recently proposed algorithm, called the RRT*, also provides asymptotic optimality guarantees, i.e., almost-sure convergence to optimal trajectories (which the RRT algorithm lacked) while maintaining the computational efficiency of the RRT algorithm. In this paper, time-optimal maneuvers for a high-speed off-road vehicle taking tight turns on a loose surface are studied using the RRT* algorithm. Our simulation results show that the aggressive skidding maneuver, usually called the trail-braking maneuver, naturally emerges from the RRT* algorithm as the minimum-time trajectory. Along the way, we extend the RRT* algorithm to handle complex dynamical systems, such as those that are described by nonlinear differential equations and involve high-dimensional state spaces, which may be of independent interest. We also exploit the RRT* as an anytime computation framework for nonlinear optimization problems.United States. Air Force Office of Scientific Research. Multidisciplinary University Research Initiative (Grant W911NF-11-1-0046)National Science Foundation (U.S.) (Grant CNS-1016213

Light-driven artificial enzymes for selective oxidation of guanosine triphosphate using water-soluble POSS network polymers.

Accepted 25 Jun 2014.The light-driven artificial enzymes were constructed to realize unnatural reactions concerning bio-significant molecules. In this manuscript, the guanosine triphosphate (GTP)-selective oxidation is reported using the network polymers composed of polyhedral oligomeric silsesquioxane (POSS). We synthesized the water-soluble POSS network polymer containing the naphthyridine ligands to capture GTP inside the networks and the ruthenium complexes to oxidize the captured GTP under light irradiation. Initially, the binding affinities of the guanosine nucleosides to the naphthyridine ligand inside the POSS network polymer were evaluated from the emission quenching experiments. Accordingly, it was observed that the naphthyridine ligand can form the stable complex only with GTP (K(a) = 5.5 × 10(6) M(-1)). These results indicate that only GTP can be captured by the network polymer. Next, the photo-catalytic activity of the ruthenium complex-modified POSS network polymer was investigated. Finally, it was revealed that the network polymer can decompose GTP efficiently under light irradiation. This is the first example, to the best of our knowledge, to offer not only the GTP-selective host polymers but also the light-driven artificial enzyme for GTP oxidation

Highly oxygen-stable CO2 reductase-catalyzed bioconversion of carbon dioxide into formate in electrochemical reactor

Electrochemical reduction of carbon dioxide (CO2) into value-added chemicals have been one of promising issues to utilize greenhouse gas for the storage of hydrogen, bioplastic, fuel cell et al. Among many potential candidates such as formate, alcohols, ethylene, etc., formate was known one of most promising chemicals through the addition of two elections and one proton during electro-catalytic reduction of CO2. Here, our group has developed efficient CO2 reductase-catalyzed conversion of CO2 into formate in electrochemical reactor. Electro-biocatalytic reduction of CO2 into formate have three main challenges. Formate dehydrogenase(FDH) have been one of potential CO2 reductase candidates but the activity of many FDHs for formate oxidation was superior than that of CO2 reduction. However, recombinant MeFDH1 in our study showed significantly higher preference for CO2 reduction with 209 (±10.66) s-1 of turnover rate than that of formate oxidation with 85.62 (± 5.76) s-1. In addition, the value of kinetic equilibrium constant (Keq), which determines the direction of reaction in reversible catalysis, implied that kinetic preference for CO2 reduction is 62.3-folds higher than that for formate oxidation. This kinetics analysis allowed MeFDH1 to be referred to as the CO2 reductase. As another challenge, Mo- or W-containing formate dehydrogenase was known vulnerable against oxygen molecule. As contrasted with the high oxygen-sensitivity of FDHs from other strains, MeFDH1 was not deactivated even under 0.13 mM of dissolved oxygen. At a range of oxygen level (0.1 % to 4 %) in the composition of Carbon Capture and Storage (CCS) gas, MeFDH1 was consequently stable without considerable decreased activity. Lastly, the long-term stability of CO2 reduction reaction system has been indispensable issue in both biocatalysts and chemical catalysts. Through the immobilization of MeFDH1, the enhanced stability for long-term operation leaded the formate formation over 500 mM with high volumetric productivity for several days

Selenoprotein W promotes cell cycle recovery from G2 arrest through the activation of CDC25B

AbstractSelenoprotein W (SelW) contains a highly reactive selenocysteine (Sec; U) in the CXXU motif corresponding to the CXXC motif in thioredoxin (Trx) and thus it appears to be involved in regulating the cellular redox state. Recent reports on the interaction between SelW and 14-3-3 suggest that SelW may be redox dependently involved in the cell cycle. However, the precise function of SelW has not yet been elucidated. Here, we show that SelW is involved in the G2–M transition, especially in the recovery from G2 arrest after deoxyribonucleic acid (DNA) damage. Knockdown of SelW significantly accumulated phosphorylated cyclin‐dependent kinase (Cdk1), which eventually led to a delay in recovery from G2 arrest. We also found that inactive Cdk1 is caused by the sustained inactivation of CDC25B, which removes the inhibitory phosphate from Cdk1. Our observation from this study reveals that SelW activated CDC25B by promoting the dissociation of 14-3-3 from CDC25B through the reduction of the intramolecular disulfide bond during recovery. We suggest that SelW plays an important role in the recovery from G2 arrest by determining the dissociation of 14-3-3 from CDC25B in a redox-dependent manner