High-speed carbon nanotube actuators based on an oxidation/reduction reaction

Actuators with a high-speed response under a high-frequency (more than 100 Hz) applied square-wave voltage of ±2 V have been developed with an electrode composed of millimeter-long single-walled carbon nanotubes synthesized by the "supergrowth method" (SG-SWNTs) and ionic liquids (ILs). Detailed studies concerning induced electric current and transferred charge in the electrode as well as cyclic voltammetric studies of the electrode revealed that the high-speed response originates from the electric current generated by an oxidation/reduction (redox) reaction in addition to electric double-layer charging. The contribution of the redox reactions of SG-SWNTs to the actuation is sensitive to the presence of supporting polymers, the thickness of the electrolyte, and the amplitude of the applied voltage.     

Correction to: Selective Cadmium Fluorescence Probe Based on Bis-Heterocyclic Molecule and its Imaging in Cells

Journal of Fluorescence - The original version of this article unfortunately contained a mistake. The equation under “Experimental -- Spectroscopic Studies” section should be corrected...     

Dineutron Formation and Breaking in 8He

We investigate the structures of the 0⁺ states in ⁸He from the viewpoint of dineutron correlation, i.e., spatial correlation between two neutrons coupled to a spin singlet. In this paper, we mainly discuss the \({0^+_2}\) state which is a candidate for the two-dineutron condensate state. This state has one α and two compact dineutrons expanded widely with little correlation with each other to form a gaslike structure.     

Solvent-free asymmetric conjugate addition of malonates to enones using a diaminomethylenemalononitrile organocatalyst

Diaminomethylenemalononitrile organocatalyst 1 efficiently promotes the asymmetric conjugate addition of malonates to α,β-unsaturated ketones to afford the corresponding addition products in high to excellent yields with up to 98% ee.     

Suppression of bitterness and improvement of palatability of commercial prednisolone powder

The aim of the study was to suppress the bitterness and improve the palatability of pediatric prednisolone powder (PP) by the addition of simple sucrose syrup (SS) and various beverages and foods. Bitterness suppression was evaluated using the human gustatory sensory test. The suppression of the bitterness and improvement of palatability of PP by addition of SS solutions was investigated using standard taste substances: sucrose for sweetness, tartaric acid for sourness, and sodium chloride as saltiness. Dilution with SS solutions of up to 50% (w/w) was successful in bitterness-suppression and improvement of palatability, but at 80% (w/w) SS, the palatability of the diluted solution was reduced. The kinematic viscosities of SS solutions were therefore evaluated using the Uberorde viscosity meter, to see whether the high viscosity of the more concentrated solutions was responsible for the reduced palatability. The kinematic viscosity of the 80% SS was 16.60 mm(2)/s. Judging from above information, the palatability might become worse when the kinematic viscosity of syrup exceeded 15 mm(2)/s. Finally, the ability of various beverages and foods with low viscosity to suppress the bitterness and improve the palatability of PP were examined. The additions of orange juice or a carbonated lemon drink to simple syrup solution were most effective in suppressing bitterness and improving palatability of PP.     

Coverage-dependent sticking probability and desorption kinetics of water molecules on Rh(111)

The adsorption and desorption kinetics of water molecules on Rh(111) were investigated using temperature programed desorption (TPD). Water molecules on Rh(111) show coverage-dependent sticking probability; the initial sticking probability is estimated to be 0.46. In the desorption process, a dilute gaslike phase and two-dimensional islands of water coexist on the surface. Based on the model proposed by Kreuzer and Payne [Surf. Sci.200, L433 (1988)], the apparent fractional-order TPD spectra can be interpreted as first-order desorption from the coexistence of two phases on which the sticking probabilities are different. Based on this, the previous estimation of pre-exponential factors assuming half-order desorption [A. Beniya et al., J. Chem. Phys.125, 054717 (2006)] should be revised.     

Capillary electrophoretic studies on the photogenotoxic potential of pharmaceutical substances

Drug-induced phototoxic skin responses, including photoirritation, photoallergy and photogenotoxicity, are identified as adverse reactions. In this study, we attempted to develop effective analytical tools to predict the photogenotoxic potential of pharmaceutical substances with the use of pBR322 DNA, a plasmid DNA. pBR322 DNA was irradiated with simulated solar light in the presence of photosensitizers, and its structural conversion was assessed by agarose gel electrophoresis (AGE), transmission electron microscopy (TEM) and capillary gel electrophoresis (CGE). The generation of reactive oxygen species (ROS) from photoirradiated photosensitizers was also assessed by spectrophotometrical determination. Concomitant ultraviolet (UV) exposure of pBR322 DNA and photosensitizers resulted in significant oxidative damage to the DNA, as evidenced by AGE, TEM and CGE data, indicating a structural transition from supercoiled form to open circular form. Photosensitizer-induced DNA damage was attenuated by the addition of radical scavengers, especially sodium azide, a typical scavenger of singlet oxygen (1 O2), and enhanced by the addition of deuterium water, an enhancer of the life time of 1 O2. These data, taken together with the results of the ROS assay, suggest that singlet oxygen might act as a major toxic species in quinine-induced photogenotoxicity. The structural analysis of plasmid DNA by CGE after exposure to UVA/B in the presence of photosensitizers could be automated, allowing easy, fast and highly reliable prediction for the photogenotoxic potential of a large number of drug candidates.     

Amyloid-beta detection with saccharide immobilized gold nanoparticle on carbon electrode

The electrochemical sensing of saccharide-protein interactions using a couple of sialic acid derivatives and Alzheimer's amyloid-beta (Abeta) is described. The densely-packed saccharide area for recognition of protein was fabricated onto a carbon electrode by three steps, which were electrochemical deposition of Au nanoparticles on a screen printed strip, self-assembled monolayer (SAM) formation of the acetylenyl group on Au nanoparticles, and the cycloaddition reaction of an azide-terminated sialic acid to the acetylenyl group. The attachment of Abeta peptides to the sialic acid layer was confirmed by electrochemistry and atomic force microscopy imaging. The intrinsic oxidation signal of the captured Abeta(1-40) and (1-42) peptides, containing a single tyrosine (Tyr) residues, was monitored at a peak potential of 0.6 V (vs Ag/AgCl within this sensor) in connection with differential pulse voltammetry. The peak current intensities were concentration dependent. The proposed process provides new routes for analysis of saccharide-protein interactions and electrochemical biosensor development.     

Kinetic study of the tocopherol regeneration reaction by biological hydroquinones in micellar solution

The rate constants (kr) of the regeneration reaction of 7-t-butyl-5-isopropyltocopheroxyl with ubiquinol-10 (UQ10H2), ubiquinol-0 (UQ0H2), alpha-, beta-, and gamma-tocopherolhydroquinones (alpha-, beta-, gamma-TQH2), 2,3,5-trimethyl-1,4-hydroquinone (TMQH2), vitamin K3 hydroquinone (VK3H2), and vitamin C (Vit C) have been measured in 2-propanol/water and micellar solutions by a stopped-flow spectrophotometer. The kr values of these hydroquinones (HQs) in micellar solution remained constant at pHs of 6-9 and increased rapidly by increasing the pH value. The kr values decreased in the order of VK3H2 > gamma-TQH2 > or = alpha-TQH2 > beta-TQH2 > or = UQ10H2 > or = TMQH2 > UQ0H2 > Vit C at pHs of 6-9. These HQs are dibasic acids and can exist in three different molecular forms, depending on pH. By comparing the kr values with the mole fraction of each molecular form of the HQs, the reaction rate kr1 for the undissociated form, kr2 for the monoanion, and kr3 for the dianion and the pKa1 and pKa2 values were determined. It has been found that the kr values of UQ10H2, alpha-TQH2, beta-TQH2, and gamma-TQH2 (plastoquinol model) are 460, 1430, 494, and 1530 times larger than that of Vit C at pH 7.0, respectively, although the values are similar to that of Vit C in 2-propanol/water. The biological HQs and Vit C coexist in many tissues of animals and plants, and thus, the relative antioxidant activities of HQs and Vit C have been tentatively discussed based on the products of kr values by concentrations in several tissues. The results suggest that these HQs show high activity for the tocopherol regeneration in biological systems.