Mode change in the self-motion of a benzoquinone disk coupled with a NADPH system

The self-motion of a benzoquinone (BQ) disk on NADPH was investigated as the coupling of an autonomous motor and an enzyme reaction. In the absence of the enzyme reaction, features of motion changed depending on the concentration of NADPH, that is, continuous motion→ intermittent oscillatory motion→ no motion. When the reverse reaction from NADP(+) to NADPH was introduced into the system with the addition of an enzyme reaction, continuous motion changed to intermittent oscillatory motion with small amplitude. The mechanism of this mode change is discussed in relation to the surface tension as a driving force and the time course of UV spectra as a window to the progress of the reaction. Characteristic features of the mode change were qualitatively reproduced by a numerical calculation.     

Theoretical Study of Clathrate Hydrates with Multiple Occupation

In this work, the electronic, structural, dynamic andthermodynamic properties of structure II, H and tetragonalAr clathrate hydrates have been calculated and the effectof multiple occupancy on their stability has been examinedusing first-principles and lattice dynamics calculations.The dynamic properties of these clathrates have beeninvestigated depending on the number of guest moleculesin a clathrate cage. It has been found that selectedhydrate structures are dynamically stable. The calculatedcell parameters are in agreement with experimental data.We also report the results of a systematic investigationof cage-like water structures using first-principles calculations. Ithas been observed that Ar clusters can be stabilized indifferent water cages and the stability is strongly dependenton the number of argon atoms inside the cages.     

Photo-impulsive reactions in the electronic ground state without electronic excitation: non-photo, non-thermal chemical reactions

Allyl phenyl ether has an absorption band in the ultraviolet region (λ < 400 nm); therefore, irradiation with few-optical-cycle ultraviolet pulses (λ = 360-440 nm) causes a transition to the ultraviolet band, which leads to an electronic state and a photo-Claisen rearrangement (radical reaction) in the electronic excited state. However, the reaction scheme of allyl phenyl ether under irradiation with few-optical-cycle visible pulses (λ = 525-725 nm) was determined to be same as that of the thermal Claisen rearrangement ([3,3]-sigmatropic rearrangement), which is symmetry-allowed in the electronic ground state. Photo-excitation with few-optical cycle visible pulses below the absorption band induces a photo-impulsive reaction in the electronic ground state without electronic excitation, of which the trigger scheme is different from that of photoreaction or thermal-reaction. The photo-impulsive reaction in the electronic ground state is highly possible as a novel reaction scheme.     

Effect of boron non-stoichiometry on B-site in perovskite type structure ScBxRh3 and CeBxRh3 on charges of atoms on A-site: study by X-ray photoelectron and nuclear magnetic resonance spectroscopies

The solid solutions of ScBRh₃-ScRh₃ and CeBRh₃-CeRh₃ are synthesized by the arc melting method, where RBRh₃ and RRh₃ (R=rare earth element) have perovskite and AuCu₃ type structures, respectively. The binding energy of Sc 2p_3/2 for ScB_xRh₃ increases with the boron concentration. The Knight shift of ⁴⁵Sc observed by nuclear magnetic resonance spectroscopy decreases with increase of boron concentration. The decrement of the Knight shift corresponds the Sc 4s electron density at the Fermi level. The intensity ratio of f²: f¹: f⁰ of Ce 3d XPS spectrum changes with boron concentration of CeB_xRh₃. It is concluded that in both cases of ScB_xRh₃ and CeB_xRh₃ the charge on the atoms on A-site changes with the concentration of the atoms on B-site, where the atoms are not directly bound.     

Preparation and certification of arsenate [As(V)] reference material, NMIJ CRM 7912-a

Arsenate [As(V)] solution reference material, National Metrology Institute of Japan (NMIJ) certified reference material (CRM) 7912-a, for speciation of arsenic species was developed and certified by NMIJ, the National Institute of Advanced Industrial Science and Technology. High-purity As₂O₃ reagent powder was dissolved in 0.8 M HNO₃ solution and As(III) was oxidized to As(V) with HNO₃ to prepare 100 mg kg^-1 of As(V) candidate CRM solution. The solution was bottled in 400 bottles (50 mL each). The concentration of As(V) was determined by four independent analytical techniques—inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry, graphite furnace atomic absorption spectrometry, and liquid chromatography inductively coupled plasma mass spectrometry—according to As(V) calibration solutions, which were prepared from the arsenic standard of the Japan Calibration Service system and whose species was guaranteed to be As(V) by NMIJ. The uncertainties of all the measurements and preparation procedures were evaluated. The certified value of As(V) in the CRM is (99.53 ± 1.67) mg kg^-1 (k = 2).     

Computational design of tetrahedral silsesquioxane-based porous frameworks with diamond-like structure as hydrogen storage materials

A novel type of three-dimensional (3D) tetrahedral silsesquioxane-based porous frameworks (TSFs) with diamond-like structure was computationally designed using the density functional theory (DFT) and classical molecular mechanics (MM) calculations. The hydrogen adsorption and diffusion properties of these TSFs were evaluated by the methods of grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The results reveal that all designed materials possess extremely high porosity (87–93 %) and large H₂ accessible surface areas (5,268–6,544 m² g^?1). Impressively, the GCMC simulation results demonstrate that at 77 K and 100 bar, TSF-2 has the highest gravimetric H₂ capacity of 29.80 wt%, while TSF-1 has the highest volumetric H₂ uptake of 65.32 g L^?1. At the same time, the gravimetric H₂ uptake of TSF-2 can reach up to 4.28 wt% at the room temperature. The extraordinary performances of these TSF materials in hydrogen storage made them enter the rank of the top hydrogen storage materials so far.     

Copper‐Free Huisgen Cycloaddition for the 14‐3‐3‐Templated Synthesis of Fusicoccin‐Peptide Conjugates

Mid‐sized molecules have emerged as an attractive chemical space and potentially provide a robust basis for the development of synthetic agents to control intracellular protein interactions. However, the limited cell permeability and chemical tractability of such agents remain to be addressed. We envisioned that target‐templated synthesis of such mid‐sized molecules might provide a solution. Here, we exploited a copper‐free Huisgen cycloaddition for template synthesis using a peptide fragment containing a 4,8‐diazacyclononyne (DACN) moiety and an azide‐containing fusicoccin derivative in the presence or absence of recombinant 14‐3‐3ζ protein in vitro. Time‐course changes in the yield of products demonstrated that the reaction was accelerated in the presence of 14‐3‐3 and one of the regioisomers was generated predominantly, supporting the template effect.     

Contribution of Discharge Excited Atomic N,N2*, and N2+ to a Plasma/Liquid Interfacial Reaction as Suggested by Quantitative Analysis

Electric-discharge nitrogen comprises three main types of excited nitrogen species-atomic nitrogen (N_atom), excited nitrogen molecules (N₂*), and nitrogen ions (N₂⁺) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N-compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The N_atom amount was analyzed quantitatively to clarify the contribution of N_atom to the P/L reaction. We focused on the quantitative relationship between N_atom and the produced N-compounds, and found that both N₂* and N₂⁺, which are active species other than N_atom, contributed to P/L reaction. The production of N-compounds from N₂* and N₂⁺ was enhanced upon UV irradiation of the water phase, but the production of N-compounds from N_atom did not increase by UV irradiation. These results revealed that the P/L reactions starting from N_atom and those starting from N₂^* and N₂⁺ follow different mechanisms.     

Acceleration of the reaction OH + CO → H + CO2 by vibrational excitation of OH

The collision complex formed from a vibrationally excited reactant undergoes redissociation to the reactant, intramolecular vibrational relaxation (randomization of vibrational energy), or chemical reaction to the products. If attractive interaction between the reactants is large, efficient vibrational relaxation in the complex prevents redissociation to the reactants with the initial vibrational energy, and the complex decomposes to the reactants with low vibrational energy or converts to the products. In this paper, we have studied the branching ratios between the intramolecular vibrational relaxation and chemical reaction of an adduct HO(v)-CO formed from OH(X(2)Π(i)) in different vibrational levels v = 0-4 and CO. OH(v = 0-4) generated in a gaseous mixture of O(3)/H(2)/CO/He irradiated at 266 nm was detected with laser-induced fluorescence (LIF) via the A(2)Σ(+)-X(2)Π(i) transition, and H atoms were probed by the two-photon excited LIF technique. From the kinetic analysis of the time-resolved LIF intensities of OH(v) and H, we have found that the intramolecular vibrational relaxation is mainly governed by a single quantum change, HO(v)-CO → HO(v-1)-CO, followed by redissociation to OH(v-1) and CO. With the vibrational quantum number v, chemical process from the adduct to H + CO(2) is accelerated, and vibrational relaxation is decelerated. The countertrend is elucidated by the competition between chemical reaction and vibrational relaxation in the adduct HOCO.     

NMR studies of phosphinenickel(0) complexes of ethyl methacrylate Ni(PR3)2(CH2=C(CH3)COOC2H5)

¹³C NMR data are given for a series of phosphinenickel(0) complexes of ethyl methacrylate (ema), Ni(PR₃)₂(CH₂=C(CH₃)COOC₂H₅) (PR₃ = PPh₃ (Ia), PEtPh₂ (Ib), PEt₂Ph (Ic), PMe₂Ph (Id), PEt₃ (Ie)). The olefinic carbon signals of ema shift upfield by 71.5–86.5 ppm on coordination, the magnitude of the upfield shift increasing with increase in the bacisity of the phosphine ligand. The effect of the basicity of PR₃ is discussed on the basis of the back-bonding from Ni to ema. Variable temperature¹H NMR studies reveal that the ema of Id, the complex having the least sterically demanding phosphine ligands, exchanges with free ema in toluene on the NMR time scale. The dependence of the rate of exchange on the concentration of ema shows that the exchange proceeds through anS_N2 mechanism. The activation parameters are: ΔH₂₇₃^≠ 2.75 kcal/mol, ΔG₂₇₃^≠ 12.7 kcal/mol, ΔS₂₇₃^≠ ?37 e.u. The³¹P NMR spectra of the complexes show two doublets when the exchange is frozen out, indicating the inequivalence of the two phosphine ligands in the ema-coordinated complex. The difference in the³¹P chemical shifts of the two coordinated tertiary phosphines increases with increase in the basicity of the PR₃ ligand.