Asymmetric total synthesis of optically active α-curcumene

(R)-(?)-α-Curcumene has been prepared in 66% optical yield and in 34% overall yield in five steps by means of asymmetric Grignard cross-coupling reaction catalyzed by a nickel complex of chiral (aminoalkylferrocenyl)phosphine as a key carbon-carbon bond forming step.     

Correlation between defect structures and dielectric constant in gallia-doped rutile (TiO2)

Dielectric constants and a.c. resistivities of rutile (TiO₂) doped with gallia (Ga₂O₃) have been measured as a function of frequency in the range 30–60 kHz at 20°C. The specimens were prepared by heating rutile single crystals on Ga₂O₃ pellets, at 1300°C, in air for various times. The dielectric constants depend on the frequency of measurement. In the c axis, the dielectric constant at low frequencies (30–100 Hz) increases as the sample heating time is extended to 1 week, but it decreases rapidly when the heating time is prolonged over 1 week. However, in the a axis, the dielectric constant does not change from the value of the starting material, being independent of the heating time. Besides dielectric measurements, the defect structures were determined using transmission electron microscopy, which showed that low concentrations of planar faults on {120} planes occur. The changes in dielectric constant are interpreted as being due to space change effects associated with Ga³⁺ ions located in the tunnels which lie parallel to the rutile c axis. Calculations are also included which show why other defects in the crystals have no effect on the value of the dielectric constant compared to pure rutile.     

(6Li,d) reactions on 24Mg and 26Mg at 73 MeV

The ^{24, 26}Mg(⁶Li, d)^{28, 30}Si reactions have been studied at 73 MeV bombarding energy. The angular distributions were analyzed with exact finite-range distorted wave Born approximation calculations assuming a direct α-cluster transfer. Extracted spectroscopic strengths leading to low-lying levels of ²⁸Si and relative spectroscopic strengths between transitions to ²⁸Si and ³⁰Si ground states are consistent with those previously obtained by several α-transfer reactions. Many strongly populated levels have been observed at E_x ? 10 MeV for ²⁸Si. A marked similarity was found between the deuteron spectrum and the ²⁴Mg(α, α)²⁴Mg excitation function in this excitation energy region. A brief comparison of the present α-transfer results with previous two-nucleon transfer data leading to ^28,30Si is also presented.     

Ultrasound-induced membrane lipid peroxidation and cell damage of Escherichia coli in the presence of non-woven TiO2 fabrics

A non-woven titanium dioxide (TiO₂) fabric was applied to disinfection by ultrasound (US) irradiation, and the disinfection efficiency and lipid peroxidation of Escherichia coli (E. coli) cell membrane were evaluated to investigate the killing process. The addition of non-woven TiO₂ fabric enhanced hydroxyl (OH) radical generation and disinfection efficiency. Judging from the disinfection experiments using glutathione or t-butanol as a radical scavenger, the OH radical played a major role in cell killing in sonodynamic disinfection with non-woven TiO₂ fabric. Moreover, to understand the detailed killing process, damage to cell membrane was also evaluated using a diphenyl-1-pyrenylphosphine (DPPP) fluorescent probe, which detects the membrane’s lipid peroxidation. The addition of non-woven TiO₂ fabric aggravated this peroxidation. This aggravation was caused by the OH radical according to an assay using a radical scavenger. From these results, it was concluded that non-woven TiO₂ fabric as a sonocatalyst promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced a major disorder in the E. coli cell membrane under US irradiation.     

Rigidity of the Álvarez class

Let ${(M,\mathcal{F})}$ be a closed manifold with a Riemannian foliation. The Álvarez class of ${(M,\mathcal{F})}$ is a cohomology class of M of degree 1 whose triviality characterizes the minimizability or the geometrically tautness of ${(M,\mathcal{F})}$ . We show that the integral of the Álvarez class of ${(M,\mathcal{F})}$ along every closed path is the logarithm of an algebraic integer if π₁ M is polycyclic or ${\mathcal{F}}$ is of polynomial growth.     

High‐Pressure Synthesis of A2NiO2Ag2Se2 (A=Sr,Ba) with a High‐Spin Ni2+ in Square‐Planar Coordination

Square‐planar coordinate Ni²⁺ ions in oxides are exclusively limited to a low‐spin state (S=0) owing to extensive crystal field splitting. Layered oxychalcogenides A₂Ni^IIO₂Ag₂Se₂ (A=Sr, Ba) with the S=1 NiO₂ square lattice are now reported. The structural analysis revealed that the Ni²⁺ ion is under‐bonded by a significant tensile strain from neighboring Ag₂Se₂ layers, leading to the reduction in crystal field splitting. Ba₂NiO₂Ag₂Se₂ exhibits a G‐type spin order at 130 K, indicating fairly strong in‐plane interactions. The high‐pressure synthesis employed here possibly assists the expansion of NiO₂ square lattice by taking the advantage of the difference in compressibility in oxide and selenide layers.     

In vitro and in vivo evaluation of microparticulate drug delivery systems composed of macromolecular prodrugs

Macromolecular prodrugs are very useful systems for achieving controlled drug release and drug targeting. In particular, various macromolecule-antitumor drug conjugates enhance the effectiveness and improve the toxic side effects. Also, polymeric micro- and nanoparticles have been actively examined and their in vivo behaviors elucidated, and it has been realized that their particle characteristics are very useful to control drug behavior. Recently, researches based on the combination of the concepts of macromolecular prodrugs and micro- or nanoparticles have been reported, although they are limited. Macromolecular prodrugs enable drugs to be released at a certain controlled release rate based on the features of the macromolecule-drug linkage. Micro- and nanoparticles can control in vivo behavior based on their size, surface charge and surface structure. These merits are expected for systems produced by the combination of each concept. In this review, several micro- or nanoparticles composed of macromolecule-drug conjugates are described for their preparation, in vitro properties and/or in vivo behavior.     

Ring-polymer Molecular Dynamics Simulation for the Adsorption of H2 on Ice Clusters (H2O)n (n=8, 10, and 12)

In the interstellar medium, the H₂ adsorption and desorption on the solid water ice are crucial for chemical and physical processes. We have recently investigated the probabilities of H₂ sticking on the (H₂O)₈ ice, which has quadrilateral surfaces. We have extended the previous work using classical MD and ring-polymer molecular dynamics (RPMD) simulations to the larger ice clusters, (H₂O)₁₀ and (H₂O)₁₂, which have pentagonal and hexagonal surfaces, respectively. The H₂ sticking probabilities decreased as the temperature increased for both cluster cases, whereas the cluster-size-independent profiles were observed. It is thought that the size independence of the probabilities is qualitatively understood from the similar binding energies for all the three cluster systems. Furthermore, the RPMD sticking probabilities are smaller than the classical ones because of the reduction in the binding energies owing to nuclear quantum effects, such as vibrational quantization.     

A highly efficient hybrid method for calculating the hydration free energy of a protein

We develop a new method for calculating the hydration free energy (HFE) of a protein with any net charge. The polar part of the energetic component in the HFE is expressed as a linear combination of four geometric measures (GMs) of the protein structure and the generalized Born (GB) energy plus a constant. The other constituents in the HFE are expressed as linear combinations of the four GMs. The coefficients (including the constant) in the linear combinations are determined using the three‐dimensional reference interaction site model (3D‐RISM) theory applied to sufficiently many protein structures. Once the coefficients are determined, the HFE and its constituents of any other protein structure are obtained simply by calculating the four GMs and GB energy. Our method and the 3D‐RISM theory give perfectly correlated results. Nevertheless, the computation time required in our method is over four orders of magnitude shorter.     

Photoresponsive change of oxygen-binding affinity of a cobalt schiff-base complex with an axially coordinating stilbazole residue of a copolymer

The reversible binding reaction of oxygen to N,N'-ethylene bis(salicylideneiminato) cobalt(II) (CoS), to which a photoisomerizable stilbazole residue of copolymer 1 coordinated, was investigated. The E form of the stilbazole residues coordinating to CoS, (E)-1-CoS, showed photoisomerization into the Z form, (Z)-1-CoS, on direct ultraviolet irradiation and negligible reverse isomerization. The oxygen-binding equilibrium constant (K) values for (E)-1-CoS and (Z)-1-CoS in toluene were 3.3 x 10(-2) mmHg-1 and 4.8 x 10(-3) mmHg(-1), respectively, at 10 degrees C. Although the pK(a) values of the E and Z forms of the stilbazole residue were similar, the oxygen-binding affinity of (Z)-1-CoS was small in terms of the linear correlation of the logarithm of K (ln K) versus the pK(a). Steric hindrance of the polymer chain of 1 on the coordination of the stilbazole residue of (Z)-1 to CoS was thought to cause the small K. A photoresponsive change of apparent oxygen-binding affinity of 1-CoS along with the E/Z isomerization of the stilbazole residues was observed. The ratio of (Z)-1-CoS converted from (E)-1-CoS by the ultraviolet irradiation could be estimated from analysis of absorption spectra for the oxygen binding of a resulting mixture of (E)-1-CoS and (Z)-1-CoS.