Adsorption of water on three-dimensional pillared-layer metal organic frameworks

We showed water adsorption isotherms at 303 K on water-resistant three-dimensional (3-D) pillared-layer metal organic frameworks (MOFs) with 1-D semi-rectangular pores, of which size depends on the length of ligand. The shapes of all three adsorption isotherms are type I by IUPAC classification showing strong water-MOFs interaction. The adsorbed amount of water molecules on the hydrophilic site of carboxylic group in 2-D sheets coincided with the crystal water amount. The adsorption on the hydrophilic sites occurs at similar relative pressure even if the used ligand is different.     

Synthesis of novel azonia Helicenes containing terminal thiophene rings

The Knoevenagel condensation of the 9‐methyl derivatives of thieno[3,2‐a]‐ and thieno[2,3‐a]‐quinolizinium salts ( 2b and 3b ) with appropriate arylaldehydes yielded 9‐(arylvinyl)thieno[3,2‐a]‐ and 9‐(arylvinyl)thieno[2,3‐a]quinolizinium salts ( 4a‐c and 5a‐c ), respectively, which underwent photocyclization to give a series of novel hetero[5]helicenes ( 6a,b and 7a‐d ) containing quinolizinium and thiophene rings.     

Natural crystallization

Natural mineral crystals grow under a broad spectrum of conditions; from vapors, from hydrothermal solutions, from magmas (high temperature solutions), or through metasomatic or metamorphic reactions. In understanding kinetic problems involved in natural crystallization, there are two ways of approach; (1) experimentally stimulating textures of rocks, and (2) decoding the paragenetic information contained in natural crystals. The latter approach is especially important, since in situ observation is impossible. Key Key features which aid in deciphering natural growth processes and conditions include external forms, surface microtopographs of crystal faces, internal inhomogeneity (growth bands, growth sectors, inclusions, twin or exsolution textures), lattice defects (plane defects, dislocations) and impurities (precipitations). Mainly based on the observations of surface microtopographs of natural crystals, characteristics of crystallization in magma, in hydrothermal solution, in vapor phase, in hydrothermal metasomatism and in regional metamorphism are analysed and reviewed in this paper. The difference and similarity between natural and synthetic crystals are also discussed.     

Large time behavior of solutions to semilinear systems of wave equations

This paper is concerned with the initial value problem for semilinear systems of wave equations. First we show a global existence result for small amplitude solutions to the systems. Then we study asymptotic behavior of the global solution. We underline that ``modified' free profiles are obtained for all global solutions to the systems even in the case where the free profile might not exist. Moreover, we prove non–existence of any free profiles for the global solution in some cases where the effect of the nonlinearity is strong enough. The first author was partially supported by Grant-in-Aid for Science Research (14740114), JSPS.     

A Single‐Crystalline Mesoporous Quartz Superlattice

There has been significant interest in the crystallization of nanostructured silica into α‐quartz because of its physicochemical properties. We demonstrate a single‐crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α‐quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li⁺ only on the surface of silica nanospheres is effective for crystallization.     

Semilinear hyperbolic systems violating the null condition

We consider systems of semilinear wave equations in three space dimensions with quadratic nonlinear terms not satisfying the null condition. We prove small data global existence of the classical solution under a new structural condition related to the weak null condition. For two-component systems satisfying this condition, we also observe a new kind of asymptotic behavior: Only one component is dissipated and the other one behaves like a non-trivial free solution in the large time.     

Synthesis and properties of cationic ionomers from poly(ester‐urethane)s based on polylactide

l ‐Lactide (l ‐LA) was polymerized in the presence of N‐methyldiethanolamine as an initiator and Sn(Oct)₂ as a catalyst to give hydroxy‐telechelic poly(l ‐lactide) (PLLA‐diol) bearing a tertiary amine group at the center of the polymer chain. Successive chain extension of the PLLA‐diol with hexamethylene diisocyanate afforded PLLA‐based poly(ester‐urethane)s (PEU) with equally spaced tertiary amine groups. Treatment of the PEU with iodomethane converted tertiary amine groups to quaternary ammonium groups to give cationic ionomers (PEU‐MeI). The thermal, mechanical, hydrophilic, and biodegradation properties of the obtained polymers were investigated. The thermal properties of the PEUs and the PEU‐MeIs were similar each other. The PEU‐MeIs exhibited higher tensile modulus than those of the starting PEUs. The contact angles of water on the PEU‐MeIs were lower than those of the PEUs with similar NMDA content indicating their higher hydrophilicity. In compost degradation tests, the PEU‐MeIs showed slower degradation than those of the PEUs. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4423–4428