We analyzed the Marangoni convection induced in the liquid crystalline material of 8CB in sandwich cells under temperature gradient. By using fluorescence photo-bleaching method, we measured the flow ...field near air interface. In the coexistence state of the smectic and the nematic phases, the direction of the observed flow was opposite from that expected from the temperature dependence of surface tension. Moreover, in the coexistence state of the nematic and isotropic phases, the flow field depended on the coating materials of the cell substrates. As for the formation of the flow field, these flow properties indicate the existence of another important physical factor in addition to the surface tension gradient.
The sympatho-adrenomedullary (SA) system is one of the body's principal responses to stress stimuli. In contrast, dysregulation of the system in response to excessive stress can contribute to the ...development of various diseases including essential hypertension and other cardiovascular events, gastrointestinal diseases and certain disorders of immune function. Therefore, to establish "fundamental" approaches for treatment of these stress-related diseases, we have to elucidate regulatory mechanisms that control the SA outflow focusing on the brain, which plays a key role in responses to stress. We have investigated a relationship between brain 2-arachodonoylglycerol (2-AG) and central regulation mechanisms for the SA outflow. 2-AG has been recognized as an endogenous ligand for cannabinoid CB receptors (endocannabinoid), which plays an inhibitory role in synaptic neurotransmission via presynaptic CB1 receptors. On the other hand, 2-AG is hydrolyzed by monoacylglycerol lipase to arachidonic acid, a precursor of prostanoids. In this symposium, we will introduce our data indicating bidirectional roles of brain 2-AG as an endocannabinoid and as a precursor of prostanoids in central regulation of the SA outflow.
In the nematic phase of 5CB, nonlinear dielectric properties induced by a shear flow were measured. The results show that a dielectric dispersion is observed in the shear-modified 3rd order ...dielectric constants and the peak of the imaginary part shifts to higher-frequencies with increasing the shear rate and the temperature. These results will be discussed from the motion of the director under the shear and the electric field.
It has been reported that if a shear flow is applied to the nematic phase of 8CB, some dynamical structure are induced. To clarify these structures is more detail, transient dielectric response after ...the application of the shear flow was measured. In the flow alignment region the dielectric permittivity decreased monotonously, while in the precession region a damped-oscillation of the dielectric permittivity was measured with critical increases in the oscillating frequency and damping faster when approaching to the nematic to smectic A phase transition point. These results will be discussed based on the fluctuation of smectic A structure.
When a steady shear flow is applied to the nematic phase of 5CB, nonlinear dielectric properties are observed. In the dielectric spectra, dielectric dispersions are recognized in the nonlinear ...dielectric constants but not in the linear one. These shear-induced nonlinear dielectric properties under the shear flow will be discussed based on the orientational change of the director under the shear and the electric fields.
Nonlinear dielectric permittivities in the quiescent state and under shear flow ware measured in the isotropic and nematic phases of liquid crystal 5CB in rest state and. In the quiscent state ...nonlinear effects related to an electrode polarization ware observed in low-frequency region (below several ten Hz) in both the isotropic and the nematic phases with the effect in the nematic phase affected by its order. On the other hand, under shear flow larger and more clearer nonlinear effects ware observed. On the basis of these results, relationship between the nonlinear dielectric property and the nematic order will be discussed.
PDF
