Preparation, Characterization and Catalysis of Intrazeolite Molybdenum, Cobalt and Cobalt–Molybdenum Sulfide Clusters: A Molecular Approach to Hydrodesulfurization Catalysts

Better understandings of the nature of Co–Mo sulfide catalysts are of great importance to a rational design of highly active hydrodesulfurization catalysts on a molecular level. Synthesis of uniform binary sulfide clusters well-defined in structure and thermally stabilized on a support is desirable for such purposes. In the present study, successful preparations, using metal carbonyls as precursors, of Mo, Co and Co–Mo sulfide clusters encaged in zeolite are reported. The structure, location and catalytic properties of the clusters are described on the basis of XPS, XAFS, XRD, XRF, IR, HREM and adsorptions of benzene and NO. Implications for the generation of catalytic synergy between Co and Mo sulfides are presented in brief. It is suggested that the host–guest interactions between zeolite framework oxygens and precursor molecules and product clusters are crucial to the size and structure of the intrazeolite clusters.     

On a boundary value problem for delay differential equations of population dynamics and Chebyshev approximation

In this paper, a boundary value problem for delay differential equations of population dynamics is considered. We obtain approximate solutions by using Chebyshev polynomial series and Newton–Raphson's procedure and give the error estimation. The method of the error estimation has been obtained in an existence theorem proved by a part of the authors. We carry out some numerical experiments by a computer language MATLAB.     

Further Study of CO2 Electrochemical Reduction on Palladium Modified BDD Electrode: Influence of Electrolyte

The study of CO₂ electrochemical reduction to useful compounds using bare or modified BDD electrode attracts numerous attentions. Meanwhile, the efficiency of products obtained from CO₂ electrochemical reduction is known to be determined by the electrode material and the electrolyte. Formic acid as main product and CO as a minor product, have also been known on the CO₂ reduction using BDD electrode. Recently, we reported the successful improvement of CO production from the reduction of CO₂ by decorating the surface of BDD electrode with palladium particles. Following this, herein, we present further investigation on electrolyte dependence, including cation and anion dependence and also concentration effect in order to understand deeply the CO₂ reduction on surface of palladium modified BDD electrode. The results suggest the use of NaCl and KCl as a catholyte for optimum performance, in addition to the improvement of CO₂ reduction product in higher electrolyte concentration.     

Novel sequential sigmatropic rearrangements of allylic diols: application to the total synthesis of (-)-kainic acid

Sequential sigmatropic rearrangements (Claisen/Claisen and Claisen/Overman) of enantiopure allylic diols are described. The reactions proceeded in complete diastereoselectivity without protecting group manipulations. The sequential Claisen/Overman rearrangement was successfully applied to the total synthesis of (-)-kainic acid.     

Dynamics of femtosecond-laser-ablated liquid-aluminum nanoparticles probed by means of spatiotemporally resolved X-ray absorption spectroscopy

We investigated spatiotemporal evolution of expanding ablation plume of aluminum created by a 100-fs, 10¹⁴–10¹⁵-W/cm² laser pulse. For diagnosing dynamic behavior of ablation plume, we employed the spatiotemporally resolved X-ray absorption spectroscopy (XAS) system that consists of a femtosecond-laser-plasma soft X-ray source and a Kirkpatrick–Baez (K–B) microscope. We successfully assigned the ejected particles by analyzing structure of absorption spectra near the L _II,III absorption edge of Al, and we clarified the spatial distribution of Al⁺ ions, Al atoms, and liquid droplets of Al in the plume. We found that the ejected particles strongly depend the irradiated laser intensity. The spatial distribution of atomic density and the expansion velocity of each type of particle were estimated from the spatiotemporal evolution of ablation particles. We also investigated a temperature of the aluminum fine particles in liquid phase during the plume expansion by analyzing the slope of the L _II,III absorption edge in case of 10¹⁴-W/cm² laser irradiation where the nanoparticles are most efficiently produced. The result suggests that the ejected particles travel in a vacuum as a liquid phase with a temperature of about 2500 to 4200 K in the early stage of plume expansion.     

How the electrolyte limits fast discharge in nanostructured batteries and supercapacitors

Solid state and interfacial processes are not necessarily the principal rate limiting process during fast discharge of LiFePO₄ composite electrodes with particle size less than 1 μm. A simple model based on salt diffusion to a sharp discharge front explains the observed dependence of discharge rate on electrode thickness, electrolyte concentration, lithium transference number, and dilution of the active material. The effect of changing the electrolyte is dramatic, e.g. discharge to 25% capacity was obtained on a 40 μm thick electrode after only 4 s in an optimised electrolyte, aqueous Li₂SO₄, showing a rate of 900 C as compared with less than 10 C for a similar cell with an ionic liquid as the electrolyte.     

Self‐Assembly of One‐ and Two‐Dimensional Hemoprotein Systems by Polymerization through Heme–Heme Pocket Interactions

Supramolecular protein polymers : When a heme moiety was introduced to the surface of an apo‐cytochrome b₅₆₂(H63C) mutant, supramolecular polymers formed through noncovalent heme–heme pocket interactions. The incorporation of a heme triad as a pivot molecule in the protein polymer further led to a two‐dimensional protein network structure, which was visualized by tapping‐mode atomic force microscopy (see picture).

     

Sequential Assembly of Phototunable Ferromagnetic Ultrathin Films with Perpendicular Magnetic Anisotropy

Getting organized : Assemblies of ferromagnetic FePt nanoparticles were generated with large perpendicular magnetic anisotropy by a magnetic‐field‐assisted layer‐by‐layer method, and subsequently layer‐by‐layer films consisting of L1₀‐FePt nanoparticles and organic polymers were prepared. These films are phototunable when photochromic molecules are used as polymer layers.