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Dielectric permittivity along theb-axis of triglycine sulfate under and after application of an electric field has been examined at various temperatures. Both relaxation behaviour of the permittivity under the application and that after discontinuance of the application are different between the transverse electric field and the longitudinal one. Temperature dependences of the permittivity prove that the memory effect which indicates the temperature where the electric field has been applied is easily observed after application of the transverse electric field. [ABSTRACT FROM PUBLISHER]

Transient currents due to the polarization reversal in triglycine sulfate were observed after application of the transverse electric field for various time intervals until the time, when theP-Ehysteresis loop could not be observed. The observed transients were fit to the switching current density calculated from the assumption that the polarization reversal occurred with growth of switched volume by motion of domain walls after nucleation of switched domains. The characteristic time decreased with the time of application of the transverse electric field, while the effective domain wall dimensionality did not show any obvious dependency. [ABSTRACT FROM AUTHOR]

Doping effects of all L-form amino acids except L-tyrosine on the crystal morphology and the ferroelectric domain structure of triglycine sulfate (TGS) have been systematically investigated. For crystals grown from solutions with L-valine, L-leucine, L-isoleucine, L-glutamine, L-proline, L-phenylalanine and L-tryptophan, both the morphology and the domain structures are almost resemble to pure TGS. For other L-form amino acids doped crystals, the growth rate in the negative b-side of seed is reduced. The generation of internal bias field Eb and the domain structure in L-alanine doped crystal is quite different from others. [ABSTRACT FROM AUTHOR]

Crystal structures of triglycine sulfate single crystals under DC and AC electric fields have been analyzed in the ferroelectric phase by X-ray diffraction. Ratio between positive domains and negative domains in the sample can be confirmed by Flack's parameter considered the X-ray anomalous dispersion effect. Atomic positions in the unit cell of both parallel and anti-parallel dipole configurations can be determined simultaneously with the split-atom method. Displacement of sulfur atom with polarization reversal turns out to be 0.14 Å. Existence ratio between these two configurations can be derived from atom occupancy probability. Long range order parameter at room temperature is estimated to be about 0.78. [ABSTRACT FROM AUTHOR]

Single crystals of triglycine sulfate (TGS) doped with various L-form amino acids have been prepared. Doping effects on the crystal morphology and the ferroelectric domain structure, and the generation of internal bias field Eb were investigated. For crystals grown from solutions with L-valine, L-leucine, and L-isoleucine, both the morphology and the domain structures were resemble to pure TGS and the generation of Eb was not realized. Doping of L-threonine, L-cysteine, L-asparagine, L-aspartic acid, and L-methionine caused obvious effect on the morphology. The effect on the domain structure and the generation of Eb in these crystals were considerably different from those in L-alanine doped crystals. [ABSTRACT FROM AUTHOR]

Recently a strange temperature dependence of the volume thermal expansion coefficient of TGS crystal has been found in the cryogenic temperature region. Therefore an electric field effect on the simultaneous measurement of the permittivity and the thermal expansion was examined under consideration of difference of a ferroelectric domain structure. The strange feature of the volume thermal expansion coefficient below 10 K was recognized again in the measurement without poling and this feature disappeared in the measurement with poling. This strange thermal expansion without poling might occur because of freezing the interaction between each area in the multi-domain state. [ABSTRACT FROM AUTHOR]

The dielectric dispersion of a triglycine sulfate single crystal has been measured after a prolonged application of the electric field perpendicular to the ferroelectric b axis. As the perpendicular electric field dwarfs the dielectric dispersion, the influence on the dielectric permittivity by the perpendicular electric field looks like the influence by the DC bias electric field parallel to the ferroelectric axis. It is concluded that the perpendicular electric field robustly immobilizes motion of the domain walls which contribute to the dielectric permittivity. [ABSTRACT FROM AUTHOR]

Sulfonylurea and glinide drugs, commonly used for antidiabetes therapies, are known to stimulate insulin release from pancreatic beta-cells by closing ATP-sensitive K+ channels. However, the specific actions of these drugs on insulin granule motion are largely unknown. Here, we used total internal reflection fluorescence (TIRF) microscopy to analyze the docking and fusion of single insulin granules in live beta-cells exposed to either the sulfonylurea drug glibenclamide or the glinide drug mitiglinide. TIRF images showed that both agents caused rapid fusion of newcomer insulin granules with the cell membrane in both control and diabetic Goto-Kakizaki (GK) rat pancreatic beta-cells. However, in the context of beta-cells from sulfonylurea receptor 1 (SUR1) knockout mice, TIRF images showed that only mitiglinide, but not glibenclamide, caused fusion of newcomer insulin granules. Compositely, our data indicate that 1) the mechanism by which both sulfonylurea and glinide drugs promote insulin release entails the preferential fusion of newcomer, rather than previously docked, insulin granules, and that 2) mitiglinide can induce insulin release by a mechanism independent of mitiglinide binding to SUR1. [ABSTRACT FROM AUTHOR]

Partially deuterated telluric acid ammonium phosphate (TAAP) single crystals were grown from water solutions with various H 2 O and D 2 O ratios. The transition temperature T C was determined from the dielectric anomaly characteristic to the second order phase transition. Deuteration molar fraction x c in the crystal was determined by a mass spectrograph. It was proved that T C increases almost linearly with x c . The maximum transition temperature reached 357 K for x c = 0.73. The deuteration effect in TAAP is clearly smaller than that in the typical hydrogen-bonded ferroelectrics such as KDP-type but considerably larger than TGS-type ferroelectrics. [ABSTRACT FROM AUTHOR]

We have further developed the clip-type strain gauge dilatometer in order to measure an angular deformation by applying the cosine theorem. In this research, not only a linear thermal expansion along three crystallographic axes but also a monoclinic angle β of ferroelectric TGS in the monoclinic system were measured below 380 K down to the cryogenic temperature region. Each of these components showed a clear bend and a typical feature of the second order transition at the Curie temperature. On the other hand, the volume thermal expansion did not show a big change at the Curie temperature. [ABSTRACT FROM AUTHOR]

It is confirmed that value of the spontaneous polarization in triglycine sulfate is reduced by a DC electric field perpendicular to its ferroelectric b axis. The reduction is influenced by temperature and by application time, intensity and direction of the perpendicular electric field. The reduced value is maintained for a long time after removing the perpendicular electric field. Charge injected into the crystal seems to be concerned with the reduction of the spontaneous polarization when considering the characteristics of electric conductivity and (de)polarization current. [ABSTRACT FROM AUTHOR]