The Raman and Infrared Spectra and Structures of Ethyl Chloride,Bromide and Iodide

The Raman, infrared and proton NMR spectra of the liquid molecules, C₂H₅-X(X[dbnd]Cl, Br, I) have been recorded. And the molecular structures have been studied on the basis of these spectra. Consequently a non-rigid structure in which a CH₂ group rotates freely with respect to the three hydrogen atoms of CH₃ group is established.     

Catalytic asymmetric mannich-type reactions activated by ZnF2 chiral diamine in aqueous media

Catalytic asymmetric Mannich-type reactions of an alpha-hydrazono ester with silicon enolates in aqueous media have been developed by using ZnF2 and chiral diamines as catalysts. In these reactions, both Zn2+ and a fluoride anion were necessary to achieve high yields and enantioselectivities, suggesting a double activation mechanism, in which Zn2+ activates the alpha-hydrazono ester and the fluoride anion simultaneously activates the silicon enolate. When chiral diamine ligands bearing methoxy-substituted aromatic rings were employed, the reactions in aqueous THF were markedly accelerated. Furthermore, the use of these diamines facilitated the asymmetric Mannich-type reactions in water without any organic cosolvents. It is noteworthy that either syn or anti adducts were stereospecifically obtained from (E)- or (Z)-silicon enolates, respectively. Interestingly, these reactions proceeded smoothly only in the presence of water. On the basis of several experimental results, it can be concluded that the reaction mechanism is likely to be a fluoride-catalyzed one, in which the ZnF2 chiral diamine complex is regenerated from the Me3SiF formed during the reaction.     

Asteropine A, a sialidase-inhibiting conotoxin-like peptide from the marine sponge Asteropus simplex

Marine sponges contain structurally intriguing and biologically active peptides of nonribosomal peptide synthase origin, often containing amino acids with novel structures. Here we report the discovery of asteropine A (APA), a cystine knot to be isolated from marine sponges. The solution structure of APA as determined by NMR belongs to the four-loop class of cystine knots similar to those of some conotoxins and spider toxins. However, the highly negatively charged surface of APA is uncommon among other cystine knots. APA competitively inhibits bacterial sialidases, but not a viral sialidase. APA was inactive against all other enzymes tested and did not have any apparent antitumor activity. Our data suggest that APA and other knotting peptides may be important leads for antibacterial and even antiviral drug development.     

Order to disorder optical phase transition in random photonic crystals

Transition process of optical modal properties induced by the introduction of randomness into random photonic crystals is investigated by a computational method. We analyze an impulse response of two-dimensional triangular photonic crystals, in which the positions of the air holes are slightly deviated to random directions. It is shown that the appropriate degree of random departure from a perfect crystal state gives rise to multiple scattering of low group velocity band-edge modes and supports their strong Anderson localization. The achieved confinement efficiency of light exceeds the one obtained in the perfect photonic crystal state.     

Evolution of two-step structural phase transition in Fe1+dTe detected by low-temperature x-ray diffraction

The low-temperature crystal structure of Fe_1.13Te, which exhibits an anomalous two-step magnetic transition, was clarified by the systematic x-ray diffraction measurements. It was found that two-step structural phase transition, tetragonal–orthorhombic–monoclinic, occurred correspondingly to the two-step magnetic transition. The detailed analysis of the profile at 5 K indicated the coexistence of the minor orthorhombic area inside the major, monoclinic lattice, which could explain the lower-shift (suppression) of the antiferromagnetic transition temperature in Fe_1.13Te and suggest a possibility of superconductivity at the domain boundary.     

Solutions for the generalized Loewner differential equation in several complex variables

We generalize a one-variable result of J. Becker to several complex variables. We determine the form of arbitrary solutions of the Loewner differential equation that is satisfied by univalent subordination chains of the form ${f(z, t)=e^{tA}z+\cdots,}We generalize a one-variable result of J. Becker to several complex variables. We determine the form of arbitrary solutions of the Loewner differential equation that is satisfied by univalent subordination chains of the form f(z, t)=e^tAz+?,{f(z, t)=e^{tA}z+\cdots,} where A ? L(\mathbbCⁿ, \mathbbCⁿ){A\in L(\mathbb{C}^n, \mathbb{C}^n)} has the property k ₊(A) < 2m(A). Here k₊(A)=max{?l:l ? s(A)}{k_+(A)=\max\{\Re\lambda:\lambda\in \sigma(A)\}} and m(A)=min{?áA(z), z ?: ||z||=1}{m(A)=\min\{\Re\langle A(z), z \rangle: \|z\|=1\}} . (The notion of parametric representation has a useful generalization under these conditions, so that one has a canonical solution of the Loewner differential equation.) In particular, we determine the form of the univalent solutions. The results are applied to subordination chains generated by spirallike mappings on the unit ball in \mathbbCⁿ{\mathbb{C}^n} . Finally, we determine the form of the solutions in the presence of certain coefficient bounds.     

Aqueous synthesis of single-crystalline ZnO prisms on graphite substrates

Morphological change from ZnO films to ZnO prisms is achieved by an electrochemical deposition method on a graphite substrate at the low temperature of 70 °C. The ZnO prisms, which are prism-shaped ZnO rods with a wide diameter, have hexagonal well-defined crystallographic facets. The ZnO prism is 1.4 μm in diameter and 1.3 μm in length. Transmission electron microscopy and electron diffraction patterns indicate that the ZnO prisms have a single-crystalline wurtzite structure with c-axis orientation. Additionally, cathodoluminescence shows that the annealed ZnO prisms in nitrogen gas emit a significant level of near-band-edge ultraviolet light.     

A novel synthesis of α,β-unsaturated nitriles from aromatic ketones via cyanophosphates

Reaction of aromatic ketones with diethyl phosphorocyanidate in the presence of lithium cyanide gave cyanophosphates, which were converted into α,β-unsaturated nitriles by treatment with boron trifluoride etherate in high yields.     

Electronic origin of the surface reconstruction and relaxation of the (001) surface of Mo and W

The reconstruction and the relaxation of the (001) surface of Mo and W are studied by using the tight-binding d band and the Born-Mayer repulsive potential. The d band parameters are set to reproduce band energies of ab initio band calculations at high symmetry points in the Brillouin zone and the parameters in the Born-Mayer potential are chosen to obtain the correct equilibrium lattice constant and the bulk modulus of the bulk crystal. First, we give a detailed discussion on the mechanism of the surface relaxation, and then show that the (001) surfaces of Mo and W are unstable to the c(2 × 2) mode but stable with regard to the (2 × 1) mode. By calculating the energy change up to the fourth order of atomic displacement, we determine the stable surface atomic structure which is in fair agreement with experiments.     

Electron cyclotron heating in high density toroidal plasmas

Wave trajectories of the ordinary mode as well as the extraordinary one injected obliquely into a magnetic field in high density toroidal plasmas, are studied theoretically. Both waves are finally converted into the electron Bernstein mode and cyclotron damped.