Cobalt-containing silicotungstate sandwich dimer [{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2]22-

The 6-cobalt-substituted [{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2]22- has been characterized by IR and UV-vis spectroscopy, elemental analysis, magnetic studies, electrochemistry, and gel filtration chromatography. A single-crystal X-ray analysis was carried out on K10Na12[{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2].49H2O (KNa-1), which crystallizes in the monoclinic system, space group P2(1)/n, with a=19.9466(8) A, b=24.6607(10) A, c=34.0978(13) A, beta=102.175(1) degrees, and Z=2. Polyanion 1 represents a novel class of asymmetric sandwich-type polyanions. It contains three cobalt ions, which are encapsulated between an unprecedented (B-beta-SiW9O34) fragment and a (B-beta-SiW8O31) unit. Polyanion 1 is composed of two sandwich species via two Co-O-W bridges in the solid state and almost certainly in solution as well based on gel filtration chromatography. UV-visible spectroscopy and cyclic voltammetry also confirmed its stability. Two well-separated groups of waves appeared in the voltammetric pattern: the wave observed in the negative potential range versus a saturated calomel electrode features the redox processes of WVI centers; the two reversible redox couples observed in the positive potential domain are attributed to the redox processes of Co2+ centers and indicated that the two types of Co2+ centers in the structure are oxidized in separate waves. Such reversibility of Co2+ centers within multi-Co-substituted polyoxometalates is uncommon. The magnetic properties of KNa-1 are also discussed. The ferromagnetic ground state has been studied by magnetic susceptibility and magnetization measurements and fitted according to an anisotropic exchange model.     

Supramolecular Chemistry of Cyclodextrin-Peptide Hybrids: Azobenzene-Tagged Peptides

AC17, which is composed of 17 amino acids and has an azobenzene moiety but has no cyclodextrin (CD) unit in the side chain, exhibits 54% helix content. However, AC17, which has both trans-azobenzene and -CD, shows 82% helix content. This result suggests that the helix structure is stabilized by host (CD)-guest (azobenzene) bridge in the side chain of the peptide. The helix content changed by trans-cis photoisomerization as shown by 64% helix content for AC17 in its cis form. This result suggests that cis-azobenzene unit is excluded from the -CD cavity, thus resulting in the smaller helix content. The helix contents for AC17, which has both azobenzene and -CD, are 94% in the cis form and 87% in the trans form, suggesting that the cis form is included in the -CD cavity. Azobenzene-tagged CD-peptide hybrids with histidine unit were also prepared and photoregulation of catalytic activity in ester hydrolysis was examined.     

Prediction of the layered ink layout for 3D printers considering a desired skin color and line spread function

Optical Review - We propose a layout estimation method for multi-layered ink using a measurement of the line spread function (LSF) and machine learning. The three-dimensional printing market for...     

Improving resolution of lensless imaging with higher harmonics of Fresnel zone aperture

Optical Review - As part of our ongoing research on lensless imaging with a Fresnel zone aperture (FZA), we propose a method of improving resolution with higher FZA harmonics. Although previous...     

Thermodynamic pressure and its fluctuations in a classical ideal gas of relativistic particles

A full and consecutive analysis of the dynamic and thermodynamic properties of an ideal gas of relativistic particles with Lorentz?CEinstein dispersion law and arbitrary number of translational degrees of freedom is carried out. Gibbs statistical mechanics is used along with Bogolyubov??s concept of quasiaverages and the generalized version of the Bogolyubov?CZubarev theorem in the classical regime well beyond the temperature of the quantum degeneracy. General expressions for a pair of equations of state, namely thermic (for the pressure) and caloric (for the inner energy) are found; the fluctuations of these quantities are also found: the compressibility and heat capacity, respectively. All expressions are found in closed form and studied in low- and high-temperature limits.