Direct observation of MoO2 crystal growth from amorphous MoO3 film

The formation process of MoO₂ crystal from amorphous MoO₃ film has been imaged by in situ observation with a transmission electron microscope. Selective growth of flower-shaped MoO₂ crystals by heating above 673 K in vacuum was directly observed. Since the MoO₂ crystal has metallic conductivity of the order of indium oxide film containing tin (ITO film), the thin film growth of the MoO₂ phase has been discussed on the basis of a new substitute for ITO film.     

A Numerical Verification Method for a System of FitzHugh-Nagumo Type

We propose a numerical method to enclose a solution of the FitzHugh-Nagumo equation with Neumann boundary conditions. We construct, on a computer, a set which satisfies the hypothesis of Schauder's fixed point theorem for a compact map in a certain Sobolev space, which, therefore contains a solution. Several verified results are presented.     

Statistical mixture design--principal component optimization for selective compound extraction from plant material

A simplex centroid design is used to optimize solvent mixtures for selective extraction of compounds from Erythrina speciosa Andrews leaves. Three main groups of compounds characterized by chromatographic retention times of 1.7, 3.1, and 6.6 min were extracted. The chromatographic peak heights registered at 1407 equally spaced times for each design extract were converted into principal components (PCs). Three PCs account for 89.1% of the data variance and have important loading values at the above retention times. Quadratic mixture models were found to adequately describe the response surfaces of their PC score values. Maximizing the first PC scores while minimizing the second and third ones results in an optimum 83% dichloromethane-17% acetone mixture that selectively extracts the group of compounds with retention times around 3.1 min. Maximizing the second PC scores and minimizing the third PC scores leads to a 78% hexane-22% acetone mixture adequate for extracting the 6.6 min retention time compounds as well as other compounds with high retention times. The 1.7 min group of compounds is most efficiently extracted on maximizing the third PC that results in a 50% ethanol-50% acetone mixture. The Derringer-Suich algorithm confirmed the determination of these optimized mixtures.     

Metal-ion-dependent GFP emission in vivo by combining a circularly permutated green fluorescent protein with an engineered metal-ion-binding coiled-coil

Coordination of metal ions significantly contributes to protein structures and functions. Here we constructed a fusion protein, consisting of a de novo designed, metal-ion-binding, trimeric coiled-coil and a circularly permutated green fluorescent protein (cpGFP), where the fluorescent emission from cpGFP was induced by metal ion coordination to the coiled-coil. A circularly permutated GFP, (191)cpGFP(190), was constructed by connecting the original N- and C-termini of GFP(UV) by a GGSGG linker and cleaving it between Asp(190) and Gly(191). The metal-ion-binding coiled-coil, IZ-HH, was designed to have three alpha-helical structures, with 12 His residues in the hydrophobic core of the coiled-coil structure. IZ-HH exhibited an unfolded structure, whereas it formed the trimeric coiled-coil structure in the presence of divalent metal ions, such as Cu(2+), Ni(2+), or Zn(2+). The fusion protein (191)cpGFP(190)-IZ-HH was constructed, in which (191)cpGFP(190) was inserted between the second and third alpha-helices of IZ-HH. Escherichia coli cells, expressing (191)cpGFP(190)-IZ-HH, exhibited strong fluorescence when the Cu(2+) and Zn(2+) ions were present in the medium, indicating that they passed through the cell membrane and induced the proper folding of the (191)cpGFP(190) domain. This strategy, in which protein function is regulated by a metal-ion-responsive coiled-coil, should be applicable to the design of various metal-ion-responsive, nonnatural proteins that work both in vitro and in vivo.     

Soft- and reactive-landing of Cr(aniline)2 sandwich complexes onto self-assembled monolayers: separation between functional and binding sites

Soft- and reactive-landing of gas-phase synthesized cationic Cr(aniline)(2) complexes onto self-assembled monolayers of methyl-terminated (CH(3)-SAM) and carboxyl-terminated (COOH-SAM) organothiolates coated on gold were performed at hyperthermal collision energy (5-20 eV). The properties of the Cr(aniline)(2) complexes on the SAM surfaces were characterized using infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD), together with theoretical calculations based on density functional theory (DFT). For the CH(3)-SAM, the Cr(aniline)(2) complexes were embedded inside the SAM matrix in a neutral charge state, keeping a sandwich structure. For the COOH-SAM, the IRAS and TPD study revealed that the amine-containing Cr(aniline)(2) complexes were bound to the SAM surface in two forms of physisorption and chemical linking through an amide bond. In the desorption, the latter form appeared as the reaction product between organothiolates and Cr(aniline)(2) above 400 K, where the organothiolate molecules, forming the SAM, were desorbed from the gold surface. The results show that the hyperthermal depositions onto a COOH-SAM bring about reactive-landing followed by covalent linking of an amide bond between the amine-containing Cr(aniline)(2) complexes to the carboxyl-terminated SAM surface, in which the binding sites can be separated from the functional sites of the d-π interaction.     

Higher-order correlated calculations based on fragment molecular orbital scheme

We have developed a new module for higher-order correlated methods up to coupled-cluster singles and doubles with perturbative triples (CCSD(T)). The matrix-matrix operations through the DGEMM routine were pursued for a number of contractions. This code was then incorporated into the ABINIT-MPX program for the fragment molecular orbital (FMO) calculations. Intra-fragment processings were parallelized with OpenMP in a node-wise fashion, whereas the message passing interface (MPI) was used for the fragment-wise parallelization over nodes. Our new implementation made the FMO-based higher-order calculations applicable to realistic proteins. We have performed several benchmark tests on the Earth Simulator (ES2), a massively parallel computer. For example, the FMO-CCSD(T)/6-31G job for the HIV-1 protease (198 amino acid residues)?Clopinavir complex was completed in 9.8?h with 512 processors (or 64 nodes). Another example was the influenza neuraminidase (386 residues) with oseltamivir calculated at the full fourth-order M?ller?CPlesset perturbation level (MP4), of which job timing was 10.3?h with 1024 processors. The applicability of the methods to commodity cluster computers was tested as well.     

Kinetic studies on the temperature dependence of the BrO + BrO reaction using laser flash photolysis

The BrO self-reaction, BrO + BrO → products (1), has been studied using laser flash photolysis coupled with UV absorption spectroscopy over the temperature range T = 266.5-321.6 K, under atmospheric pressure. BrO radicals were generated via laser photolysis of Br(2) in the presence of excess ozone. Both BrO and O(3) were monitored via UV absorption spectroscopy using charge-coupled device (CCD) detection. Simultaneous fitting to both temporal concentration traces allowed determination of the rate constant of the two channels of , BrO + BrO → 2Br + O(2) (1a); BrO + BrO → Br(2) + O(2) (1b), hence the calculation of the overall rate of and the branching ratio, α: k(1a)/cm(3) molecule(-1) s(-1) = (1.92 ± 1.54) × 10(-12) exp[(126 ± 214)/T], k(1b)/cm(3) molecule(-1) s(-1) = (3.4 ± 0.8) × 10(-13) exp[(181 ± 70)/T], k(1)/cm(3) molecule(-1) s(-1) = (2.3 ± 1.5) × 10(-12) exp(134 ± 185 /T) and α = k(1a)/k(1) = (0.84 ± 0.09) exp[(-7 ± 32)/T]. Errors are 1σ, statistical only. Results from this work show a weaker temperature dependence of the branching ratio for channel (1a) than that found in previous work, leading to values of α at temperatures typical of the Polar Boundary Layer higher than those reported by previous studies. This implies a shift of the partitioning between the two channels of the BrO self-reaction towards the bromine atom and hence directly ozone-depleting channel (1a).     

Facile synthesis of picene from 1,2-di(1-naphthyl)ethane by 9-fluorenone-sensitized photolysis

A facile formation of picene was achieved by photosensitization of 1,2-di(1-naphthyl)ethane using 9-fluorenone as a sensitizer. This sensitized photoreaction is the first photochemical cyclization of ethylene-bridged naphthalene moieties to afford the picene skeleton. 5,8-Dibromopicene, prepared by this procedure using 1,2-di[1-(4-bromonaphthyl)]ethane as the substrate, was readily converted to novel functionalized picenes by conventional substitution and cross-coupling reactions.