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...     

Production of $$^{178}$$ 178 Hfm2 and a simple chemical separation method for Hf recovery

Journal of Radioanalytical and Nuclear Chemistry - The nuclear isomer $$^{178}$$ Hfm2 enables various investigations owing to its unique properties. To study exotic nuclear reactions induced by...     

Underwater current distribution induced by spark discharge on a water surface

Discharge current distributions generated underwater by spark discharges from the atmosphere to free water surfaces with conductivities in the range 0.07–10.0 S/m were investigated using a laboratory-scale electrode system consists of a discharge electrode and nine underwater grounding electrodes. Discharge emission on the water surface, which shows significant change with slight increase in conductivity, affects the current distribution in the water. The electric potential of the water surface also changes significantly with slight increase in conductivity. Results of numerical calculations of the underwater discharge current based on the water surface potential agree with the experimental results.     

A NEW APPLICATION OF INORGANIC CLUSTER,CARBORANES FOR MEDICINAL DRUG DESIGN AND MOLECULAR CONSTRUCTION

The inorganic cage compounds, dicarba-closo-dodecaboranes (carboranes), are chemical building blocks of remarkable thermal and chemical stability, with spherical geometry and exceptional hydrophobic character. We have focused on medicinal drug design using carboranes as a hydrophobic pharmacophore and have developed a potent estrogen agonist, BE120. We also have applied carboranes for structural chemistry, utilizing their specific three-dimensional character to obtain multilayer aromatic structures.     

The α‐Glycosidation of Partially Unprotected N‐Acetyl and N‐Glycolyl Sialyl Donors in the Absence of a Nitrile Solvent Effect

The synthesis of α‐sialosides is one of the most difficult reactions in carbohydrate chemistry and is considered to be both a thermodynamically and kinetically disfavored process. The use of acetonitrile as a solvent is an effective solution for the α‐selective glycosidation of N‐acetyl sialic acids. In this report, we report on the α‐glycosidation of partially unprotected N‐acetyl and N‐glycolyl donors in the absence of a nitrile solvent effect. The 9‐O‐benzyl‐N‐acetylthiosialoside underwent glycosidation in CH₂Cl₂ with a good α‐selectivity. On the other hand, the 4,7,8‐O‐triacetyl‐9‐O‐benzyl‐N‐acetylthiosialoside was converted to β‐sialoside as a major product under the same reaction conditions. The results indicate that the O‐acetyl protection of the sialyl donor was a major factor in reducing the α‐selectivity of sialylation. After tuning of the protecting groups of the hydroxy groups at the 4,7,8 position on the sialyl donor, we found that the 9‐O‐benzyl‐4‐O‐chloroacetyl‐N‐acetylthiosialoside underwent sialylation with excellent α‐selectivity in CH₂Cl₂. To demonstrate the utility of the method, straightforward synthesis of α(2,9) disialosides containing N‐acetyl and/or N‐glycolyl groups was achieved by using the two N‐acetyl and N‐glycolyl sialyl donors.     

Controlled ring‐opening polymerization of l‐lactide and ε‐caprolactone catalyzed by aluminum‐based Lewis pairs or Lewis acid alone

Ring‐opening polymerization of cyclic esters was studied using catalysts composed of bulky Lewis acids (LA) and Lewis bases (LB). Controlled polymerization of l ‐lactide (l ‐Lac) was proceeded by Al(C₆F₅)₃·THF in combination with trimesitylphosphine (Mes₃P) or triphenylphosphine (Ph₃P) using BnOH as an initiator to produce poly(l ‐Lac) with narrow molecular weight distribution (MWD; M_w/M_n = 1.1). Both the LA and the LB were indispensable to promote the polymerization. The molecular weights of the resulting poly(l ‐Lac)s were controlled by the feed monomer to initiator ratio. ε‐Caprolactone (CL) was rapidly polymerized by Al(C₆F₅)₃·THF with or without Mes₃P, although the resulting polymer had rather broad MWD (M_w/M_n = 1.7). The CL polymerization by Al(C₆F₅)₃·THF alone at r.t. gave poly(CL) with relatively narrow MWD (M_w/M_n = 1.2). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 297–303