No abstract

The piezoelectricity of a film of the eco-material poly(L-Lactic acid) (PLLA) with high transparency and flexibility has been noted for its possibility of application to new types of devices used in mobile equipment. However, for its application, there are many difficult problems to be solved, because the PLLA film has poor thermal stability. To change the high-order structure of the PLLA film, thus realizing an improvement in the temperature dependence of its piezoelectricity, a composite film with a stereocomplex crystal (SC) formed from PLLA and poly(D-lactide acid) (PDLA) molecules was fabricated. As a result, we obtained a composite film with a stable piezoelectric temperature dependence compared with a pure PLLA film. To analyze its piezoelectric temperature dependence, we first observed the high-order structure of the composite film using a polarized microscope (POM). However, we did not find any difference between the high-order structures of the composite film and the pure PLLA film. In contrast, from observation by atomic force microscopy (AFM), it was found that the grain structure in the composite film became more homogeneous than that in the pure PLLA film. These experimental results indicate that, by changing the high-order structure through a compound with SC, the external stress always has a constant effect over a wide temperature range and, as a result, the induced polarization is constant in the composite film. Thus, the composite film shows excellent thermal stability of piezoelectricity compared with the pure PLLA film.

Thiocyanate hydrolase (SCNase) is a cobalt-containing enzyme with a post-translationally modified cysteine ligand, cCys131-SO 2 H. When the SCNase a, b and c subunits were expressed in Escherichia coli, the subunits assembled to form a hetero-dodecamer, (abc) 4 , like native SCNase but exhibited no catalytic activity. Metal analysis indicated that SCNase was expressed as an apo-form irrespective of the presence of cobalt in the medium. On the contrary, SCNase co-expressed with P15K, encoded just downstream of SCNase genes, in cobalt-enriched medium under the optimized condition (SCNase (+P15K) ) possessed 0.86 Co atom/abc trimer and exhibited 78% of the activity of native SCNase. SCNase (+P15K) showed a UV-Vis absorption peak characteristic of the SCNase cobalt center. About 70% of SCNase (+P15K) had the cCys131-SO 2 H modification. These results indicate that SCNase (+P15K) is the active holo-SCNase. P15K is likely to promote the functional expression of SCNase probably by assisting the incorporation of cobalt ion.

A ferroelectret porous polyethylene (Fp-PE) film with a thickness of 30 mm and a porosity of 58% was fabricated; its perpendicular piezoelectric constant d 33 was 80 pC/N. In the Fp-PE film observed by atomic force microscopy (AFM), pores with a diameter of about 0.3 mm were almost homogeneously distributed. Moreover, from piezoresponse force microscopy (PFM), it was found that areas surrounding the pores shift in one direction following the application of ac voltage, but that areas far from the pores cannot move freely. These results indicate that the electrical charges trapped in areas surrounding the pores in the Fp-PE film play an important role in piezoelectricity.

Polymer stabilized SSFLCDs have been successfully fabricated. A liquid crystalline polymer network in a device cell is formed by the photo-cure of UV photo-currable liquid crystalline monomers that are doped in an FLC, where both the rubbed polyimide (PI) and non-rubbed but linearly polarized UV irradiated poly(viny1 cinnamate) (PVCi) films are utilized as surface FLC molecular alignment. The actual monomers adopted is acrylate with a mesogenic side chain. The PVCi is one of the photo alignment polymer. The fabrication process of these SSFLC cells is as follows; first the photo-cure is done on a monomers and initiators doped LC medium at the temperature where this material takes SmA phase and then the cell is cooled down to room temperature, at which the medium takes SmC* phase. The layer structure of the liquid crystalline polymer stabilized (LC-PS) FLC cells has been investigated by X-ray diffraction measurement. As the experimental results, it is found that the formed polymer network suppresses the formation of a chevron layer structure, resulting in the formation of a quasibookshelf layer structure; the only C1-uniform state is spontaneously formed without giving a high surface pretilt angle; and a fairly good memory state with an excellent contrast ratio and a low threshold voltage are obtained for a low concentration of doped monomers (2 -3 wt?h) in particular with photo-alignment layers of PVCi; and furthermore, in a cell with a higher concentration of doped monomers (4 wt%) an excellent electroclinic like behavior (called the quasi-electroclinic effect) is obtained.