Photocatalytic oxidation of acetaldehyde by hybrid Pt/WO3–MOR photocatalysts under visible or sunlight irradiation

A hybrid photocatalyst was prepared from visible light-responsive Pt/WO₃ and siliceous mordenite (MOR) zeolite by simple impregnation with an aqueous solution of (NH₄)₁₀W₁₂O₄₁·5H₂O. Unmodified Pt/WO₃ had low photocatalytic activity in gas phase oxidation of acetaldehyde because of its low surface area (3–5 m²/g). In contrast, the Pt/WO₃–MOR had higher photocatalytic activity under focused sunlight and Xe lamp irradiation. Pt/WO₃–MOR with low WO₃ content (<20 wt%) adsorbed sufficient acetaldehyde, but absorption of light in the visible region was low. The optimum zeolite content enhancing the photocatalytic activity of Pt/WO₃ was estimated to be 30–50 % (w/w). Adsorption of the gaseous reactants and the efficiency of absorption of incident light are both important aspects of high photocatalytic activity.     

Visualization of ripples on the surface of a rising bubble through an immiscible oil/water interface

Abstract  

This paper visually demonstrates instantaneous behavior of ripples propagating on the surface of a rising bubble through an oil/water interface. This experiment uses potassium iodide (KI) 31 wt% as refractive index matching material which makes the water phase invisible. As a result, the generated micro droplets, which are shown in the preceding paper (Uemura et al. in Europhys Lett 92:34004, 2010), cannot be visible in the present results, and therefore the droplets are positively confirmed to be made of water.     

Quadrature phase-shifting interferometer using spatial carrier

We propose a high-speed phase measurement using a phase calculation algorithm in a quadrature phase-shifting interferometer (QPI), which is applied to tilted fringes. Although the spatial carrier method is useful for a high-speed measurement with a single imaging sensor, the spatial resolution in conventional phase calculation algorithms is reduced owing to the use of three or more phase-shifted data at different sample points. Phases in the QPI method can be calculated with only two quadarture phase-shifted data extracted from the tilted fringes before and after a phase change of the interferometer. Thus, the proposed method can suppress the reduction of the spatial resolution compared with that in conventional methods, and makes it possible to measure a phase at high-speed. The principle and experimental results of this technique are presented.     

Dimerization and charge order in hollandite K₂V₈O₁₆

The metal-insulator transition occurring in hollandite K?V?O?? has been studied by means of neutron and x-ray diffraction as well as by thermodynamic and electron-spin resonance measurements. The complete analysis of the crystal structure in the distorted phase allows us to identify dimerization as the main distortion element in insulating K?V?O??. At low-temperature, half of the V chains are dimerized perfectly explaining the suppression of magnetic susceptibility due to the formation of spin singlets. The dimerization is accompanied by the segregation of charges into chains.     

Non-Gaussian fluctuations resulting from power-law trapping in a lipid bilayer

Anomalous diffusion in lipid bilayers is usually attributed to viscoelastic behavior. We compute the scaling exponent of relative fluctuations of the time-averaged mean square displacement in a lipid bilayer, by using a molecular dynamics simulation. According to the continuous time random walk theory, this exponent indicates non-Gaussian behavior caused by a power-law trapping time. Our results provide the first evidence that a lipid bilayer has not only viscoelastic properties but also trapping times distributed according to a power law.     

Extracting electron-ion differential scattering cross sections for partially aligned molecules by laser-induced rescattering photoelectron spectroscopy

We extract large-angle elastic differential cross sections (DCSs) for electrons scattering from partially aligned O2+ and CO2+ molecules using rescattering photoelectrons generated by infrared laser pulses. The extracted DCSs are in good agreement with those calculated theoretically, demonstrating that accurate DCSs for electron-ion scattering can be extracted from the laser-induced rescattering spectra, thus paving the way for dynamic imaging of chemical reactions by rescattering photoelectron spectroscopy.     

Electron-transfer-mediated decay and interatomic Coulombic decay from the triply ionized states in argon dimers

We report the first observation of electron-transfer-mediated decay (ETMD) and interatomic Coulombic decay (ICD) from the triply charged states with an inner-valence vacancy, using the Ar dimer as an example. These ETMD and ICD processes, which lead to fragmentation of Ar(3+)-Ar into Ar(2+)-Ar(2+) and Ar(3+)-Ar+, respectively, are unambiguously identified by electron-ion-ion coincidence spectroscopy in which the kinetic energy of the ETMD or ICD electron and the kinetic energy release between the two fragment ions are measured in coincidence.     

Co-doped Y2O3:Tb3+/Tm3+ multicolor emitting phosphors for thermometry

In this study, the new temperature-dependent phosphor, Y2O3:Tb3+/Tm3+, was investigated for high-temperature thermometry. The photoluminescence intensity at 456?nm emitted from Tm3+ was strong at temperatures higher than 1100?K, whereas the peak intensities emitted from Tb3+ decreased due to the thermal quenching effect. Thus, the intensity ratio between those emissions showed an appropriate variation for thermometry over a wide temperature range. In addition, the phosphors showed a distinct change of visible emission colors from green to blue with increasing temperature. These findings suggest the applicability of these phosphors in visual thermo-sensors.     

Transient dissociation of the transducer protein from anabaena sensory rhodopsin concomitant with formation of the M state produced upon photoactivation

Anabaena sensory rhodopsin (ASR), a microbial rhodopsin in the cyanobacterium sp. PCC7120, has been suggested to regulate cell processes in a light-quality-dependent manner (color-discrimination) through interaction with a water-soluble transducer protein (Tr). However, light-dependent ASR-Tr interaction changes have yet to be demonstrated. We applied the transient grating (TG) method to investigate protein-protein interaction between ASR with Tr. The molecular diffusion component of the TG signal upon photostimulation of ASR(AT) (ASR with an all-trans retinylidene chromophore) revealed that Tr dissociates from ASR upon formation of the M-intermediate and rebinds to ASR during the decay of M; that is, light induces transient dissociation of ASR and Tr during the photocycle. Further correlating the dissociation of the ASR-Tr pair with the M-intermediate, no transient dissociation was observed after the photoexcitation of the blue-shifted ASR(13C) (ASR with 13-cis, 15-syn chromophore), which does not produce M. This distinction between ASR(AT) and ASR(13C), the two isomeric forms in a color-sensitive equilibrium in ASR, provides a potential mechanism for color-sensitive signaling by ASR.     

Two‐Dimensional Perovskite Oxynitride K2LaTa2O6N with an H+/K+ Exchangeability in Aqueous Solution Forming a Stable Photocatalyst for Visible‐Light H2 Evolution

Undoped layered oxynitrides have not been considered as promising H₂‐evolution photocatalysts because of the low chemical stability of oxynitrides in aqueous solution. Here, we demonstrate the synthesis of a new layered perovskite oxynitride, K₂LaTa₂O₆N, as an exceptional example of a water‐tolerant photocatalyst for H₂ evolution under visible light. The material underwent in‐situ H⁺/K⁺ exchange in aqueous solution while keeping its visible‐light‐absorption capability. Protonated K₂LaTa₂O₆N, modified with an Ir cocatalyst, exhibited excellent catalytic activity toward H₂ evolution in the presence of I^? as an electron donor and under visible light; the activity was six times higher than Pt/ZrO₂/TaON, one of the best‐performing oxynitride photocatalysts for H₂ evolution. Overall water splitting was also achieved using the Ir‐loaded, protonated K₂LaTa₂O₆N in combination with Cs‐modified Pt/WO₃ as an O₂ evolution photocatalyst in the presence of an I₃^?/I^? shuttle redox couple.