Associative desorption of adsorbed oxygen promoted by translational energy of incident O2 molecules

Effects of the translational energy of incident oxygen molecules on surface processes from dissociative adsorption to subsequent associative desorption on Pt(1 1 1) have been investigated by means of supersonic molecular beam scattering. The reaction rate of associative desorption increases with the incident translational energy. The enhanced associative desorption can be attributed to nonthermal diffusion of dissociated oxygen, promoted by the translational energy of incoming molecules.     

Optimal harvesting policy of an inland fishery resource under incomplete information

A new mathematical model for finding the optimal harvesting policy of an inland fishery resource under incomplete information is proposed in this paper. The model is based on a stochastic control formalism in a regime‐switching environment. The incompleteness of information is due to uncertainties involved in the body growth rate of the fishery resource: a key biological parameter. Finding the most cost‐effective harvesting policy of the fishery resource ultimately reduces to solving a terminal and boundary value problem of a Hamilton‐Jacobi‐Bellman equation: a nonlinear and degenerate parabolic partial differential equation. A simple finite difference scheme for solving the equation is then presented, which turns out to be convergent and generates numerical solutions that comply with certain theoretical upper and lower bounds. The model is finally applied to the management of Plecoglossus altivelis, a major inland fishery resource in Japan. The regime switching in this case is due to the temporal dynamics of benthic algae, the main food of the fish. Model parameter values are identified from field measurement results in 2017. Our computational results clearly show the dependence of the optimal harvesting policy on the river environmental and biological conditions. The proposed model would serve as a mathematical tool for fishery resource management under uncertainties.     

Core–Shell Pd@M (M=Ni,Cu, Co) Nanoparticles/Graphene Ensembles with High Mass Electrocatalytic Activity Toward the Oxygen Reduction Reaction

Herein, it is demonstrated that pyrene butyric acid (PBA)-stabilized metal nanoparticles with core–shell morphology, Pd@M_NPs (M=Ni, Cu, Co), non-covalently supported on graphene (G) sheets, are more active towards oxygen electroreduction in alkaline environments than the benchmark Pd/C catalyst, albeit with a 70 % lower precious metal loading. The PBA-stabilized Pd@M_NPs (M=Ni, Cu, Co)/G ensembles were prepared by employing a simple modified polyol method and galvanic replacement and thoroughly characterized with advanced microscopy imaging and complementary spectroscopic techniques. Electrochemical studies revealed that Pd@Ni_NPs/G presents the optimum performance, exhibiting a 30 mV more positive onset potential and 3.2 times greater mass activity over Pd/C. Moreover, chronoamperometric assays showed the minimum activity loss for Pd@Ni_NPs/G, not only among its core–shell counterparts but importantly when compared with the benchmark catalyst. The excellent performance of Pd@Ni_NPs/G was attributed to the (a) presence of PBA as stabilizer, (b) uniform Pd@Ni_NPs dispersion onto the graphene sheets, (c) efficient intra-ensemble interactions between the two species, (d) existence of the core–shell structure for Pd@Ni_NPs, and (e) stability of the Ni core metal under the reaction conditions. Last, the oxygen reduction on Pd@Ni_NPs/graphene occurs by the direct four-electron reduction pathway, showing great potential for use in energy related applications.     

Three-Dimensionally Integrated Micro-solution Plasma: Numerical Feasibility Study and Practical Applications

This paper describes effects of design parameters for a three-dimensionally integrated micro-solution plasma (3D IMSP) reactor, which generates a large amount of microplasma in gas bubbles flowing with a liquid medium through a porous dielectric material. Electric fields in gas bubbles are calculated by solving Maxwell’s equations under the electro-quasi-static approximation. The calculated electric fields in the bubbles can be high enough for igniting electrical discharge in the bubbles even if the bubbles are surrounded by electrically conductive liquid. We show importance of higher permittivity of a dielectric-reactor tube and a higher voltage-rise rate for obtaining higher electric fields in the bubbles. Using a proto type 3D IMSP reactor, we demonstrate synthesis of gold nanoparticles and decomposition of methylene blue molecules in aqueous solution.     

Myoglobin Reconstituted with Ni Tetradehydrocorrin as a Methane‐Generating Model of Methyl‐coenzyme M Reductase

Myoglobin reconstituted with Ni tetradehydrocorrin was investigated as a model of F430‐containing methyl‐coenzyme M reductase, which catalyzes anaerobic methane generation. The Ni^II tetradehydrocorrin complex has a Ni^II/Ni^I redox potential of ?0.34 V vs. SHE and EPR spectroscopy indicates the formation of a Ni^I species upon reduction by dithionite. This redox potential is approximately 0.31 V more positive than that of F430. The Ni^I tetradehydrocorrin moiety is bound to the apo‐form of myoglobin to yield the reconstituted protein. Methane gas is generated in the reaction of the model with methyl iodide in the presence of the reconstituted protein under reductive conditions, whereas the Ni^I complex itself does not produce methane gas. This is the first example of a protein‐based functional model of F430‐containing methyl‐coenzyme M reductase.     

Trajectory of the spectral/structural rearrangements for photo-oxidative reaction of neat ketoprofen and its cyclodextrin complex

Journal of Inclusion Phenomena and Macrocyclic Chemistry - Ketoprofen is a nonsteroidal anti-inflammatory drug used as mohrus tape which causes unwanted photosensitivity due to UV irradiation. In...     

Synthesis of functionalized pentacenes from isobenzofurans derived from C-H bond activation

The synthesis of unsymmetric functionalized pentacenes from 1,4-anthraquinones and functionalized isobenzofurans, which were prepared by transformation via C-H bond activation, was successfully accomplished. Examples of the synthesis of pentacenes with functional groups at the 5-position are still rare. These obtained functionalized pentacenes are highly soluble in hexane, toluene, and THF.     

Stereoselective Synthesis of cis‐β‐Methyl‐ and Phenyl‐Substituted Alkenylboronates by Platinum‐Catalyzed Dehydrogenative Borylation

Changing places : Intramolecular B(pin)/H exchange took place in the presence of a platinum–phosphane catalyst, giving synthetically useful cis‐β‐methyl‐substituted alkenylboronates stereoselectively (see scheme; B(pin)=4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl).

     

Rhenium-catalyzed insertion of aldehyde into a C-H bond: synthesis of isobenzofuran derivatives

A rhenium complex, [ReBr(CO)3(thf)]2, catalyzed reactions of aromatic ketimines with aldehydes to give isobenzofuran derivatives in good to excellent yields. In contrast to ruthenium and rhodium catalysts, aldehydes, which are polar unsaturated molecules, inserted into the C-H bond after activation by the rhenium complex.