Chiral Interlocked Corrole Dimers Directly Linked at Inner Carbon Atoms of Confused Pyrrole Rings

A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face-to-face intramolecularly interlocked corrole dimers were formed by the oxidative C−C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials.     

Computational Analysis Reveals a Critical Point Mutation in the N-Terminal Region of the Signaling Lymphocytic Activation Molecule Responsible for the Cross-Species Infection with Canine Distemper Virus

Infection of hosts by morbilliviruses is facilitated by the interaction between viral hemagglutinin (H-protein) and the signaling lymphocytic activation molecule (SLAM). Recently, the functional importance of the n-terminal region of human SLAM as a measles virus receptor was demonstrated. However, the functional roles of this region in the infection process by other morbilliviruses and host range determination remain unknown, partly because this region is highly flexible, which has hampered accurate structure determination of this region by X-ray crystallography. In this study, we analyzed the interaction between the H-protein from canine distemper virus (CDV-H) and SLAMs by a computational chemistry approach. Molecular dynamics simulations and fragment molecular orbital analysis demonstrated that the unique His28 in the N-terminal region of SLAM from Macaca is a key determinant that enables the formation of a stable interaction with CDV-H, providing a basis for CDV infection in Macaca. The computational chemistry approach presented should enable the determination of molecular interactions involving regions of proteins that are difficult to predict from crystal structures because of their high flexibility.     

Homohelicity induction of propylene-linked zinc bilinone dimers by complexation with chiral amine and α-amino esters. Preorganization of structurally coupled homohelical subunits

Homohelicity induction of a series of propylene-linked zinc bilinone (ZnBL; linear tetrapyrrople-zinc(II) complex) dimers upon complexation with chiral amine and α-amino esters was investigated. Introduction of substituents such as dimethyl and diisobutyl to the central carbon of the propylene spacer gave rise to stabilization of the homohelical (PP and MM) conformers rather than the heterohelical (PM) conformer. As bulkiness of the substituent increased, stability of the homohelical conformers was raised. The preorganization of the homohelical structures led to significantly amplified homohelicity induction upon complexation with chiral amine and α-amino esters.     

Reaction of C3 and C4 ketoses with alkenals and alkenones in water

Treatment of 1,3-dihydroxyacetone and acrolein with aqueous KOH gave a tetrahydrofuran derivative, 1,4-dihydroxy-3,7-dioxabicyclo[3.3.0]octane, in 80% yield. Similarly, 6-alkyl substituted 1,4-dihydroxy-3,7-dioxabicyclo[3.3.0]octanes were obtained by reaction of 1,3-dihydroxyacetone with various α,β-unsaturated aldehydes. In the cases of long chain alkenals, the reaction was effectively accelerated in the presence of organic co-solvent. On the other hand, the corresponding tricyclic products were synthesized by reaction of 1,3-dihydroxyacetone with cyclic enones, such as 2-cyclopentenone and 2-cyclohexenone. This method was successfully applied to the reaction of a tetrulose in the absence of any protecting groups.     

The kinetics of the light-induced defect creation in hydrogenated amorphous silicon – Stretched exponential relaxation

Our model for light-induced defect creation in hydrogenated amorphous silicon is applied to its kinetics, i.e., the growing curve of light-induced dangling bond density as a function of illumination time, which is fitted to a stretched exponential function. Two parameters β and τ involved in the function are estimated as functions of saturated dangling bond density in terms of our model. These are compared with two experimental results, i.e., our results obtained from ESR measurements and Shimakawa et al.’s results obtained from photoconductivity measurements. The saturated dangling bond density is also measured as a function of the generation rate of free carriers. The experimental results are compared with calculated results and discussed.     

Classical in-plane negative magnetoresistance and quantum positive magnetoresistance in undoped InSb thin films on GaAs (1 0 0) substrates

Magnetoresistance (MR) effects have been investigated in perpendicular and parallel magnetic fields at 300, 80 K and liquid He temperatures for undoped InSb thin films 0.1–2.3 μm thick grown on GaAs(1 0 0) substrates by MBE. At high temperatures, the intrinsic carriers show the parabolic negative MR observable only in magnetic fields parallel to the film. The skipping-orbit effect due to surface boundary scattering in the classical orbits in the plane vertical to the film has been argued to be responsible for the negative MR. At low temperatures (T=80 K), the transport is dominated by the two-dimensional (2D) electrons in the accumulation layers at the InSb/GaAs(1 0 0) hetero interface; MR is positive and shows a logarithmic increase with anisotropy between parallel and perpendicular field orientation, arising from the 2D weak anti-localization (WAL) that reflects the interplay between the spin-Zeeman effect and strong spin–orbit interaction caused by the asymmetric potential at the interface (Rashba term). The zero-field spin splitting energy of Δ₀13 meV, the electron effective mass of m^*0.10m₀ seven times of the band edge mass in bulk InSb and the effective g-factor of |g^*|15 in the accumulation layer have been inferred from fits of MR for the 0.1 μm thick film to the 2D WL theory.     

Mutation detection in the drug-resistant hepatitis B virus polymerase gene using nanostructured reverse micelles.

The emergence of drug-resistant hepatitis B virus (HBV) has been reported in patients with prolonged administration of lamivudine, which is a potent drug for the prevention of HBV infection. Lamivudine-resistant HBV has several types of mutations at the YMDD motif of its DNA polymerase. We successfully demonstrated that monitoring the hybridization behavior in nanostructured reverse micelles enables us to detect single nucleotide polymorphisms (SNPs). With the aid of reverse micelles, a model 40-mer oligonucleotide containing a single-base substitution was clearly distinguished from the normal, complementary oligonucleotide. In addition, we extended this technique to a high-throughput analysis. The results obtained with a 96-well micro-plate reader indicated the possibility of SNPs detection toward multiple samples of patients.     

Development of a “Built-in” Scanning Near Field Microscope Head for an Atomic Force Microscope System and Stress Mapping of an Al2O3/ZrO2 Eutectic Composite

We constructed a scanning near-field optical microscope (SNOM) on a commercially available atomic force microscopy (AFM) apparatus (SPM-9500J2; Shimadzu Corp.) to measure the stress distribution in ceramic composite materials. Features of our SNOM system are: (1) a compact SNOM head substituted for the original AFM head; (2) a wide scanning range (125 × 125 μm²) inherited from the original scanner; (3) use of conventional shear-force regulation; (4) an optical system for the illumination-collection (I-C) mode; (5) excitation by a 488 nm line of an Ar-ion laser, and (6) light detection by photon counting or a polychromator equipped with an electronically cooled charge coupled device (CCD). This SNOM system was used to measure the surface structure and stress distribution of an Al₂O₃/ZrO₂ eutectic composite. We simultaneously measured topographic images and fluorescence spectra of an Al₂O₃/ZrO₂ eutectic composite. We estimated its peak intensity, peak position, and peak width from the fluorescence spectrum during scanning, which respectively correspond to the abundance of Al₂O₃, stress in the grain, and the anisotropy of that stress. Mapping images showed that the stress and its anisotropy were weaker in the center of the Al₂O₃ grain than its boundary between Al₂O₃ and ZrO₂. That observation suggests that Al₂O₃ underwent intense anisotropic stress induced by volume expansion in the phase transition of ZrO₂ from the cubic phase to the monoclinic phase during preparation.