The effect of ionic repulsion among hydrophilic groups of arachidic acid molecules on the aggregation structure of the arachidic acid monolayer on the water surface was investigated on the basis of surface pressure-surface area (π-A) isotherm measurements, Fourier transform infrared spectroscopic (FT-IR) measurements, and transmission electron microscopic (TEM) observations. π-A isotherm and FT-IR measurements revealed that the degree of ionic dissociation of hydrophilic groups in the monolayer drastically changed in a pH range of 10-12. The arachidic acid monolayer in a slightly dissociated state of hydrophilic groups (pH ) 5.8) did not exhibit the phase transition from an amorphous state to a crystalline one during compression. On the other hand, the monolayer in a highly dissociated state (pH ) 12.6) showed the phase transition from an amorphous state to a crystalline one by surface compression at the subphase temperature, T sp, below the melting temperature, Tm, of the monolayer, and also, the monolayer was still in an amorphous state without the phase transition to a crystalline state at Tsp above Tm. The aggregation structure of the monolayers on the water surface was systematically classified into "the crystalline monolayer", "the amorphous monolayer", and "the compressing crystallized monolayer" with respect to the thermal and chemical (intermolecular repulsive) factors.

The new complexes [ FeL' ,] CIO, (H L' = tridentate Schiff base formed by 1 : 1 condensation of o-aminophenol and pyridine-2-carbaldehyde) and [FeL2,] NCS (H L2 = tridentate Schiff base formed by 1 : 1 condensation of 8-aminoquinoline and salicylaldehyde) were synthesized. The spincrossover behaviour between S = : and : which is dependent on temperature was observed for the solid complexes using variable-temperature 57Fe Mossbauer spectral and magnetic measurements.Both compounds show a pronounced hysteresis effect in the high spin + low spin transition. For [ FeL' ,] CIO,, sharp and strong Mossbauer absorptions were observed over the temperature range examined and the effective vibrating mass, Meff., was evaluated using the high-temperature approximation of the Debye model. The value for the low-spin isomer was larger than that for the high-spin isomer. The complex [ FeL2,J NCS when freshly recrystallized below 280 K is predominantly in a low-spin state. However, the magnetism at room temperature increases with time, spin-crossover behaviour is exhibited, and the magnetism is dependent on temperature, with a pronounced hysteresis loop of about 70 K at 286 K 10 d after preparation.

No abstract

The objectives of this study were to investigate the distribution and chemical characteristics of cations in annual rings of Japanese cedar (Cryptomeriajaponica D. Don) grown in a healthy stand of an unindustrialized region in Japan and discuss the possibility of using cations in tree-rings as a chronological index of acidic deposition. Radial distributions of some cations and P at different vertical positions of the stem were analyzed for five trees from the same mountain. Each cation and P in all trees showed a specific distribution in its radial pattern but similar distribution trends were observed at all vertical positions. The cations and P were classified into three groups: (I) constant radial concentrations (Ca 2 + , Sr 2 +, Na ÷ , and probably Ba 2 +), (II) high concentrations in the heartwood and low in the sapwood (Mg +, K + , Rb ÷ , Cs +), and (IH) increasing concentrations in sapwood (P, Mn z ÷, Cũ +). The total concentration of cations exceeded the calcium-binding capacity (CBC) of the wood, and the excess was attributed to K + in a salt form. The CBC increased from the sapwood/ heartwood boundary toward the pith in the heartwood but remained constant in the sapwood. The increase of CBC in the heartwood was consistent with the profile of Mg 2+ , indicating a transfer of Mg + into heartwood and fixation on the acquired binding site. The radial distribution of 9°Sr was closely related to the cumulative deposition of fallout from the nuclear weapon tests, but that of ~TCs was unrelated. This suggests immobility of Sr~ + and mobility of Cs ÷ in the horizontal direction of wood. The conservation of the historical ~eSr/Sr2 + change indicated that no influence of heartwood formation on the chemical environment of Sr~+ in cedar xylem and a possibility of using Sr + as a chronological index of nutrient availability. A steady-state in nutrient availability is speculated for trees growing in this mountain because all of the trees analyzed show constant radial distributions of Sr 2 + for decades.