Association behavior of one-end hydrophobically modified poly[<Emphasis Type="Italic">N</Emphasis><Superscript>5</Superscript>-(2-hydroxyethyl) <Emphasis Type="SmallCaps">l</Emphasis>-glutamine] in water/ethylene glycol mixed solvent

Amphiphilic polymers Cn-PHEG consisting of water-soluble poly[N ⁵-2-(hydroxyethyl) l-glutamine] (PHEG) and hydrophobic alkyl chain (carbon number n = 12, 14, 16, or 18) attached at the PHEG terminal was prepared, and association behavior and structure of associate for Cn-PHEG in selective solvent (water/ethylene glycol mixed solvent) have been investigated. α-Helix content of PHEG block for all the polymers increased with weight fraction of ethylene glycol in the mixed solvent (W _EG). By light scattering measurements, formation of a small micelle was suggested for C14-, C16-, and C18-PHEG when W _EG = 0. With the increase in W _EG, appearance of a larger associate was revealed for C16- and C18-PHEG. Evaluated molecular weight and radius of gyration suggested that the micelle is star-like sphere when W _EG = 0 and worm-like cylinder when W _EG = 0.7. C12-PHEG did not demonstrate any distinct micellization behavior because of the weak hydrophobicity of C12 chain.     

Omaezallene from Red Alga Laurencia sp.: Structure Elucidation,Total Synthesis,and Antifouling Activity

Natural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene‐containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of omaezallenes were also evaluated.     

In situ 18F-γ-ray-induced Ag nanoparticle formation in the presence of SiO2 nanoparticles under air

The in situ ¹⁸F-γ-ray irradiation of SiO₂ nanoparticles in an aqueous solution containing Ag⁺ led to the reduction of Ag⁺ to Ag⁰ aggregates or Ag⁰ nanoparticles in a small volume (0.1 ml) under air. ¹⁸F was used in the form of ¹⁸F-fluorodeoxyglucose, produced by a cyclotron at our University hospital. The in situ average absorbed dose at the distance of 1 µm in the solution volume (0.1 ml) was calculated to be 12.2 kGy equivalent to a point source of 20 MBq. The SiO₂ nanoparticles had two effects; they enhanced the reduction of Ag⁺ to Ag⁰ aggregates and they acted as reaction sites to prevent aggregation. When Ag⁺ adsorbed on the surface of the SiO₂ nanoparticles, Ag nanoparticles were formed by ¹⁸F γ-rays. The absorption spectra of Ag nanoparticles and Ag⁰ aggregates were markedly different.     

Intermolecular interactions in the extraction system nicotinic acid-water-poly(N-vinylpyrrolidone)

Computer simulation of molecular structures in the nicotinic acid-water and nicotinic acid-water-poly(N-vinylpyrrolidone) systems was performed, and the IR spectra of these systems were calculated. The theoretical and experimental IR spectra were compared. Parameters of hydrogen bonds in the studied systems were calculated.     

Optimal design of coating material for nanoparticles and its application for low-temperature interconnection

Metal nanoparticles need coating material so as to avoid aggregating to each other. On the contrary, there are occasions when the coating materials are required to be removed. Here, a theoretical model to relate removability of coating materials to their molecular structure is suggested. The model is used to find an optimum coating material, secondary amine, for use in low-temperature interconnection material. An interconnection made of methyloctylamine-coated silver nanoparticles was formed between a pair of copper electrodes by heating and pressurizing the nanoparticles and electrodes at 250 °C and 2.5 MPa, respectively, for 150 s. Shear strength and thermal conductivity of the formed interconnection were 17.8 MPa and 219 W/mK, respectively. This thermal conductivity value is greater than that obtained using Pb–Sn and silver solders.     

The kinetics of the gas-phase reaction between ozone and alkenes

The rate law ? d[O₃]/ dt = k₁[A][O₃] + k₃[A][O₃]²/ (k₄ + k₅[O₂]) has been found to obtain for the reaction of ozone with allene and with 1,2-butadiene. We now find that this rate law also applies to the reaction of ozone with ethylene and presumably with all lower alkenes. This generalizes the inhibiting effect of oxygen and accounts for the simplifed rate law found in the presence of excess oxygen. Oxygen itself is a product of the ozone–ethylene reaction, and we find that as [O₃]₀ increases, the (O₂ formed)/(O₃ used) ratio approaches 1.5. Values of k₁, k₃/k₅ for ethylene are compared with those for allene, 1,3-butadiene, and propene. A generalized mechanism is postulated for the reaction of ozone with alkenes involving a chain sequence that produces oxygen and which accounts for the observed rate law. A specific mechanism is postulated for the reaction of O₃ with ethylene, and the thermochemistry of the chain sequence is examined in detail.     

Electrical properties, structure, and surface morphology of poly(p-xylylene)–silver nanocomposites synthesized by low-temperature vapor deposition polymerization

The crystalline structure, surface morphology, electrical, and optical properties of thin films of nanocomposites consisting of silver nanoparticles embedded in poly(p-xylylene) matrix prepared by low-temperature vapor deposition polymerization were studied. Depending on the filler content, the average size of silver nanoparticles varied from 2 to 5 nm for nanocomposites with 2 and 12 vol.% of silver, correspondingly. The optical adsorption in the visible region due to surface plasmon resonance also exhibited a clear correlation from silver content, revealing a red shift of the adsorption peak with the increase of the metal concentration. The temperature dependences of the dc resistance of pure p-xylylene condensate and p-xylylene–silver cocondensates during polymerization as well as temperature dependences of the formed poly(p-xylylene)–silver nanocomposites were examined. The observed variation of the temperature dependences of electrical resistance as a function of silver concentration are attributed to different conduction mechanisms and correlated with the structure of the composites. The wide-angle X-ray scattering and AFM measurements consistently show a strong effect of silver content on the nanocomposite structure. The evolution of the size of silver nanoparticles by thermal annealing was demonstrated.     

Chemo-enzymatic synthesis of spiro type gem-difluorocyclopropane as core molecule candidate for liquid crystal compounds

The synthesis of a novel spiro type gem-difluorocyclopropane building block, 1,1,7,7-tetrafluoro-2,8-bis(hydroxymethyl)dispiro[2.2.2.2]decane (1), has been accomplished in optically pure form using chemo-enzymatic reaction protocol. Various types of diesters or dialkyl ether were prepared from diol (+)-1 or (−)-1 in optically active form and their helical twisting power (HTP) was evaluated by addition of 1.0 wt% to a non-chiral nematic liquid crystal host. Although their HTP values were not significant, all compounds showed liquid crystal property with SmC* phase when they were dissolved (20 wt%) in achiral nematic host liquid crystal.     

Synthesis and properties of 1,4,8,11,15,18,22,25-octaalkoxy-2,3,9,10,16,17,23,24-octakis(phenylthio)phthalocyaninato copper(II)

1,4,8,11,15,18,22,25-Octaalkoxy-2,3,9,10,16,17,23,24-octakis(phenylthio)phthalocyaninato copper(II) was synthesized. They were easily soluble in organic solvents and their Q-bands showed bathochromic shifts about 100 nm compared with unsubstituted phthalocyaninato copper(II). Their properties were examined.