Preparation and thermal behavior of poly-p-phenylene diacrylic acid dimethyl ester

The photopolymerization behavior of p-phenylene diacrylic acid dimethyl ester (p-PDA Me) crystal and the thermal behavior of the resultant poly-p-PDA Me were investigated. From the kinetic study of polymerization at various temperatures a topochemical process via a stepwise mechanism was observed. Continuous change from monomer to polymer crystals was demonstrated by x-ray diffraction pattern and DSC analysis. Crystallinity of the reacting phase was maintained at an extremely high degree during the polymerization process in support of monomer crystal lattice control. Thermal study on as-polymerized poly-p-PDA Me crystal confirmed that the thermal reaction was a polymer crystal lattice-controlled depolymerization, which was followed by miscellaneous processes that involved vaporization, sublimation, and deterioration of the oligomeric or monomeric units of p-PDA Me. Thermal stability was dependent on the molecular weight. All the results are compared with those of four-center-type photopolymerization in the crystalline state.     

Silica with Bimodal Pores for Solid Catalysts Prepared from Water Glass

The comparison of bimodal pore structures between silica gels prepared from silicon alkoxide and from water glass was performed based on the results of phase separation tendency, mesopore formation, and atomic scale observation using ²⁹Si NMR. Macropore structure could be controlled for both the raw material systems by inducing phase separation. Although the gelation in the water glass system is much faster than that in the silicon alkoxide system, there is little difference in the atomic scale structure, mesopore evolution during processing, and phase separation tendency. The results suggest that the obtained bimodal porous silica from water glass is essentially the same as that from silicon alkoxide. Because of the low cost of water glass, water-glass-derived bimodal porous silica is applicable to industrial use.     

Mechanochemical synthesis of rutile-type CrMO4 (M=V, Sb) and their solid solutions

Grinding a mixture of hydrous amorphous chromium oxide (Cr₂O₃·nH₂O), vanadium oxide (V₂O₅) and antimony oxide (Sb₂O₅) was conducted by using a planetary ball mill, to investigate their mechanochemical reactions to form chromium vanadium oxide (CrVO₄) and chromium antimony oxide (CrSbO₄). The synthesis reactions proceed with an increase in grinding periods of time. The ground samples consist of agglomerates with particle size of about ten nanometers. The synthesized CrVO₄ sample exhibits a rutile-type tetragonal crystal structure, which is a high pressure phase. Additionally, solid solutions, CrV_1−xSb_xO₄ (x=0∼1, Δx=0.25), have been synthesized mechanochemically from the mixtures of Cr₂O₃·nH₂O, V₂O₅ and Sb₂O₅.     

Determination of Stability Constants for Alkanol/α-Cyclodextrin Inclusion Complexes using the Surface Tension Method

The stability constants for the inclusion of alkanols with-cyclodextrin (-CD) in aqueous solutionhave been determined using the surface tension method. Dataanalyses assuming 1 : 1 stoichiometry were appliedto estimate the stability constants of thesecomplexes. The stability constants obtained using this methodwere in reasonable agreement with the corresponding values inthe literature. Chemically modified -CDs could not beused in this method because those CDs themselves have surfaceactivity. In addition, the relation between the stability constantsand the carbon number of alkanols is discussed.     

Expansion of repertoire of modified DNAs prepared by PCR using KOD Dash DNA polymerase

Thymidine analogues bearing a variety of functional groups at the C5-position via an amino-linker arm were prepared and the substrate activity for PCR using thermophilic KOD Dash DNA polymerase was examined. The enzyme accepted the thymidine analogues bearing pyridine, imidazole, biotin, a cationic-charged guanidinium, a cationic-charged amino, mercaptopyridyl and phenanthrolne groups at the C5-position, forming the corresponding PCR product. However, a thymidine analogue bearing a carboxyl group at the C5-position was a poor substrate and the corresponding PCR products could not be obtained. The thymidine analogue bearing a mercapto group was also a poor substrate for the enzyme, because it dimerized by disulfide linkage under PCR conditions. The enzyme hardly accepts the thymidine analogues with a negatively-charged carboxyl group or a bulky group as a substrate. KOD Dash DNA polymerase, having a broader substrate specificity than any other DNA polymerase, will expand the variety of modified DNAs that can be prepared by PCR.     

Thermal and transport properties of copoly(γ-stearyl L-glutamate-γ-methyl L-glutamate)

Copoly(γ-stearyl L-glutamate-γ-methyl L-glutamate)s with various compositions were synthesized by ester exchange of poly(γ-methyl L-glutamate) with stearyl alcohol. The temperature dependence of the volume and helical spacing of the copolyglutamates thus prepared was examined from 0 to 100°C, observing the melting and crystallization of the long alkyl side chain attached to the polypeptide backbone. The melting temperature of the long side chain increased with increasing stearyl L-glutamate content. With increasing temperature, the α helical spacing decreased, especially with the melting of the side chain. On the other hand, the volume increased with increasing temperature and a marked increase was observed on melting. The above two phenomena were elucidated according to the structural model of the long side chain of the copolyglutamates proposed here. The transport properties, permeability coefficients were found to be considerably affected by the side-chain structure of the copolyglutamate and by the melting or crystallization of the side chain. The permeability coefficient of the copolyglutamate with 67% degree of stearylation, varied as much as two orders of magnitude before and after melting or crystallization. It was also confirmed that the permeability coefficient is controllable by the side-chain structural change of polypeptides.     

Synthesis of 1,2,9,10-tetrakis(N-phenylamino)[2.2]metacyclophane by SmI2-mediated reductive coupling of diimine

SmI₂/HMPA-mediated double reductive coupling of N,N′-(m-xylylidene)dianiline affords 1,2,9,10-tetrakis(N-phenylamino)[2.2]metacyclophane in good yield.     

Fabrication of microbial chip using collagen gel microstructure

A microbial chip was fabricated by filling the micropores on a glass substrate with collagen-embedded Escherichia coli(E. coli) cells, and characterized by scanning electrochemical microscopy (SECM) in a solution containing ferricyanide. The activity of the E. coli cells in the collagen gel microstructure was imaged and characterized with SECM by mapping the localized concentration of ferrocyanide produced by the respiration of the cells. The SECM-based activity measurement detected as low as approximately 100 E. coli cells. Furthermore, the optical-microscopic observation indicated that the E. coli cells on the chip proliferated during the incubation. The sequential SECM measurements were performed for the same E. coli chip to obtain the microbial growth curve for a small number of microorganisms.