Thermal behavior and dismantlability of adhesives containing various inorganic salts

As a fundamental study on the development of dismantlable adhesives containing chemically reactive materials, the thermal behavior and dismantlability of an epoxy adhesive containing one of the twenty-seven inorganic salts (chlorides, perchlorates, and nitrates) were observed. In the thermal behavior measured by the differential scanning calorimetry, epoxy adhesives with inorganic salts containing iron, copper, zinc, and aluminum cations released heats of reaction at lower temperatures than the adhesive alone or the adhesives with other inorganic salts. Since such inorganic salts were considered to be effective candidates as fillers in dismantlable adhesives, the adhesion strengths of their mixtures with the adhesive were observed after heat aging at 270 °C for 30 min. The results showed that both chloride and perchlorate salts specifically decreased the adhesion strength after heating. On the other hand, the effect of nitrate salts on the decrease in adhesion strength was low in comparison with the chloride and perchlorate salts.     

Mannose‐Binding Geometry of Pradimicin A

Pradimicins (PRMs) and benanomicins are the only family of non‐peptidic natural products with lectin‐like properties, that is, they recognize D ‐mannopyranoside (Man) in the presence of Ca²⁺ ions. Coupled with their unique Man binding ability, they exhibit antifungal and anti‐HIV activities through binding to Man‐containing glycans of pathogens. Notwithstanding the great potential of PRMs as the lectin mimics and therapeutic leads, their molecular basis of Man recognition has yet to be established. Their aggregate‐forming propensity has impeded conventional interaction analysis in solution, and the analytical difficulty is exacerbated by the existence of two Man binding sites in PRMs. In this work, we investigated the geometry of the primary Man binding of PRM‐A, an original member of PRMs, by the recently developed analytical strategy using the solid aggregate composed of the 1:1 complex of PRM‐A and Man. Evaluation of intermolecular distances by solid‐state NMR spectroscopy revealed that the C2–C4 region of Man is in close contact with the primary binding site of PRM‐A, while the C1 and C6 positions of Man are relatively distant. The binding geometry was further validated by co‐precipitation experiments using deoxy‐Man derivatives, leading to the proposal that PRM‐A binds not only to terminal Man residues at the non‐reducing end of glycans, but also to internal 6‐substituted Man residues. The present study provides new insights into the molecular basis of Man recognition and glycan specificity of PRM‐A.     

Investigation of the biosynthesis of acetyl-CoA and oxaloacetic acid from pyruvic acid and the quantitative evaluation of incorporated 13C-labeled l-alanine in Arthrobacter hyalinus

Studies on the contribution to acetyl-CoA and oxaloacetic acid from the pyruvic acid transformation from l-alanine in Arthrobacter hyalinus were conducted by means of feeding experiments with l-[1-¹³C]alanine and l-[3-¹³C]alanine, followed by an analysis of the labeling patterns of coproporphyrinogen III using ¹³C NMR spectroscopy. The results demonstrated that l-alanine was transformed via pyruvic acid to both acetyl-CoA and oxaloacetic acid. Additionally, the quantitative analysis indicated that pyruvic acid was transformed to acetyl-CoA and oxaloacetic acid in the ratio of 1:0.8.     

A principle in dynamic coarse graining–Onsager principle and its applications

Dynamic coarse graining is a procedure to map a dynamical system with large degrees of freedom to a system with smaller degrees of freedom by properly choosing coarse grained variables. This procedure has been conducted mainly by empiricisms. In this paper, I will discuss a theoretical principle which may be useful for this procedure. I will discuss how to choose coarse grained variables (or slow variables), and how to set up their evolution equations. To this end, I will review the classical example of dynamic coarse graining, i.e., the Brownian motion theory, and show a variational principle for the evolution of the slow variables. The principle, called the Onsager principle, is useful not only to derive the evolution equations, but also to solve the problems.     

Improved Crystallinity of Poly(3-hexylthiophene-2,5-diyl):[6,6]-Phenyl-C61 Butyric Acid Methyl Ester Film by Pulsed Electrospray Deposition

We investigated crystallinity parameters and ordering domains of poly(3-hexylthiophene-2,5-diyl) blended in [6,6]-phenyl-C₆₁-butyric acid methyl ester films, which were fabricated by pulsed electrospray deposition methods. The crystallinity parameter and the ordering domain were estimated from Raman and optical absorption spectra, respectively. As a result, they were improved with decreasing the off time of pulse voltage, corresponding to the slow evaporation speed of solvent. In addition, both the space-charge limited current mobility and the photoconversion efficiency showed same trend. A highest photoconversion efficiency of 1.11 % was achieved without the thermal annealing process after depositing the active layer.     

Palladium‐Catalyzed Coupling Reaction of Perfluoroarenes with Diarylzinc Compounds

This report describes the first Pd⁰‐catalyzed cross‐coupling of hexafluorobenzene (C₆F₆) with diarylzinc compounds to give a variety of pentafluorophenyl arenes. This reaction could be applied to other perfluoroarenes, such as octafluorotoluene, pentafluoropyridine, and perfluoronaphthalene, to give the corresponding polyfluorinated coupling products. The optimal ligand in this catalytic reaction was PCy₃, and lithium iodide was indispensable as an additive for the coupling reaction. One of the roles of lithium iodide in this catalytic reaction was to promote the oxidative addition of one C?F bond of C₆F₆ to palladium. Stoichiometric reactions revealed that an expected oxidative‐addition product, trans‐[Pd(C₆F₅)I(PCy₃)₂], generated from the reaction of [Pd(PCy₃)₂] with C₆F₆ in the presence of lithium iodide, was not involved in the catalytic cycle. Instead, a transient three‐coordinate, monophosphine‐ligated species, [Pd(C₆F₅)I(PCy₃)], emerged as a potential intermediate in the catalytic cycle. Therefore, we isolated a novel Pd^II complex, [Pd(C₆F₅)I(PCy₃)(py)], in which pyridine (py) acted as a labile ligand to generate the transient species. In fact, in the presence of lithium iodide, this Pd^II complex was found to react smoothly with diphenylzinc to give the desired pentafluorophenyl benzene, whereas the same reaction conducted in the absence of lithium iodide resulted in a decreased yield of pentafluorophenyl benzene, which indicated that the other role of lithium iodide was to enhance the reactivity of the organozinc species during the transmetalation step.     

High‐Quality Three‐Dimensional Nanoporous Graphene

We report three‐dimensional (3D) nanoporous graphene with preserved 2D electronic properties, tunable pore sizes, and high electron mobility for electronic applications. The complex 3D network comprised of interconnected graphene retains a 2D coherent electron system of massless Dirac fermions. The transport properties of the nanoporous graphene show a semiconducting behavior and strong pore‐size dependence, together with unique angular independence. The free‐standing, large‐scale nanoporous graphene with 2D electronic properties and high electron mobility holds great promise for practical applications in 3D electronic devices.     

The electronic band structure analysis of OLED device by means of in situ LEIPS and UPS combined with GCIB

Low-energy inverse photoelectron spectroscopy (LEIPS) and ultraviolet photoelectron spectroscopy (UPS) incorporated into the multitechnique XPS system were used to probe the ionization potential and the electron affinity of organic materials, respectively. By utilizing gas cluster ion beam (GCIB), in situ analyses and depth profiling of LEIPS and UPS were also demonstrated. The band structures of the 10-nm-thick buckminsterfullerene (C₆₀) thin film on Au (100 nm)/indium tin oxide (100 nm)/glass substrate were successfully evaluated in depth direction.     

Radical copolymerization of N-alkylmaleimides with isobutene and the properties of the resulting alternating copolymers

Radical copolymerization of N-methylmaleimide (MeMI) as well as other N-alkylmaleimides (RMI) and isobutene (IB) was carried out with 2,2′-azobis(isobutyronitrile) as an initiator at 60°C. The initial rate of the copolymerization (R_p) was dependent on the monomer composition and was maximum at the 40 mol % of MeMI in the feed. A solvent effect on the R_p and the monomer reactivity ratio was observed in this copolymerization system, i.e., copolymerization in chloroform produced a higher R_p and an alternating tendency compared with those in dioxane (r_MeMI = 0.14, r_1B = 0 in chloroform and r_MeMI = 0.47, r_1B = 0 in dioxane). The alternating copolymer of RMI and IB shows a high glass transition temperature (T_g) and excellent thermal stability, e.g., the T_g and the thermal decomposition temperature (T_d) were 152 and 363°C, respectively, for the alternating copolymer of MeMI and IB. Both the T_g and T_d increased as the concentration of the MeMI unit in the copolymers increased. Colorless transparent sheets were obtained from press molding the alternating copolymers. They showed excellent mechanical and optical properties. © 1996 John Wiley & Sons, Inc.