SYNTHESIS AND CHARACTERIZATION OF POLY(ASPARTIC ACID) AND ITS DERIVATIVES AS BIODEGRADABLE MATERIALS

ABSTRACT

Three types of modified poly(aspartic acid)s, such as poly(aspartic acid-co-aminocarboxylic acid) (4), alkylamine modified poly(aspartic acid) (5) and crosslinked poly(aspartic acid) (6), were synthesized and calcium-ion chelating ability, hygroscopicity and water absorption were evaluated. The calcium-ion chelating ability of 4 depended on the kind of aminocarboxylic acids and the content of aminocarboxylic acid in the copolymer. The highest value was 3 times higher than that of poly(acrylic acid) with a M_w of 14000. The highly modified PASP, e.g., 50 mol% lauryl amine modified poly(aspartic acid), showed the highest by grogroscopicity among homopoly(aspartic acid)s and modified poly(aspartic acid)s. The maximum swelling of poly(aspartic acid) hydrogel prepared by the γ-irradiation of homopoly(as-partic acid) was 3400 g-deionized water/g-dry hydrogel.     

Ground state properties of S = 1 antiferromagnetic chain systems studied by ESR

Electron spin resonance (ESR) was used to study the ground state properties of two kinds of spin (S) one Heisenberg antiferromagnetic chain systems, namely a uniform chain system (HAUC), which is well known as the Haldane system, and a bond alternating chain system (HABA). To investigate and compare the features of the ground state, two nickel chain compounds doped with non-magnetic Zn²⁺ impurities were studied. The HAUC was modelled with Ni(1,3-pn)₂(μ-NO₂)(ClO₄)(1,3-pn = 1,3-propanediamine), abbreviated as NINO, while the HABA was modelled with Ni(333-tet)(μ-NO₂)(ClO₄) (333-tet = bis-(3-aminopropyl)-1,3-propanediamine), abbreviated as NTENP. Both systems have a singlet ground state with an excitation gap. The ground state of NINO approximates well to the valence bond solid state, thus producing S = 1/2 spins at the sites neighbouring the impurities. The angular dependence of the ESR signals of NINO:Zn is explained by the anisotropy of the g tensor for spin 1/2. On the other hand, the ground state of NTENP is expected to be in the singlet dimer phase based on the ratio of alternating bond strengths. In this case, it is expected that the S = 1 spins will appear at the sites neighbouring the impurities without forming the singlet dimer. From ESR studies of NTENP:Zn was observed the triplet state (S = 1), induced by the impurity doping, which is consistent with the above picture.     

Three Dimensional Numerical Flow Simulation Around Parallel Rectangular Cylinders

Noises of flow around parallel rectangular cylinders are likely to be caused by wind flow. According to the wind tunnel experiment, it is known that there are three kinds of special noises. Two kinds of noises occur when the wind comes from a perpendicular direction to the cylinders. These noises are caused by the vortex excited oscillation. Another noise occurs when the wind comes from an inclined direction to the cylinders. This noise is very high frequency, and its mechanism is not clear. Therefore in this study, the three dimensional numerical flow simulation is performed to clarify the high frequency noise of flow around parallel rectangular cylinders.     

In-situ Infrared Study on Surface Species in Selective Catalytic Reduction of NO with Hydrocarbon over Copper ZSM-5 Zeolite

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The synthesis and mesomorphic properties of ferroelectric liquid crystals with a fluorinated asymmetric frame

A novel series of ferroelectric liquid crystals with a fluorinated asymmetric frame were synthesized by utilizing optically active (S)-2-, (S)-3-, (S)-4- and (S)-5-fluoroalkanols prepared from corresponding (R)-1,2-epoxyalkanes. Their mesomorphic and physical properties, such as spontaneous polarization, optic tilt angle and response time, were investigated systematically in a series of homologous compounds having the chiral centre at different positions on tails of various lengths. All the compounds exhibited the chiral smectic C phase in a wide range of temperatures and were found to possess a fast response time in spite of the small magnitude of the spontaneous polarization.     

铜离子交换分子筛上NO吸附的IR光谱及TPD研究

采用原位IR光谱及TPD技术研究了NO在铜离子交换分子筛上各种表面物种的生成及脱附,并与NO在Cu-ZSM-5上的分解反应性能相关联,考察了Cu-ZSM-5反应活性高的原因及O₂的生成机理。NO的吸附状态随分子筛母体种类及铜离子交换度的不同而变化,交换度较高的ZSM-5催化剂上容易形成NO-3物种,该物种对NO分解及O₂的生成具有重要作用。