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The tubulin dimers of microtubules are arranged in a crystalline lattice which is wrapped to form a long cylinder. Two different arrangements of monomers within the lattice have been postulated: the A-lattice and the B-lattice. Previous studies have assumed that both lattice types are hexagonal with each dimer surrounded by six nearest-neighbors. Based on recent biochemical studies I argue that both lattice types can also be formed with each dimer having four nearest-neighbors. This has important consequences for the overall behavior of the model. It is generally assumed that tubulin dimers possess a mobile electric dipole which can exist in one of two discrete Ising spin states: -1 (down) or +1 (up). The average of all these states within a microtubule is the mean polarization and is a measure of the dipole ordering within the lattice. Microtubule models with six nearest-neighbors behave like models of ferroelectric substances: at low temperatures the lattice is highly ordered with most (if not all) dipoles pointing in the same direction, but as the temperature increases, the degree of ordering decreases due to random thermal flipping of the dipoles. The mean polarization is particularly erratic at physiological temperatures. In contrast, when the microtubule lattice is modeled with four nearest-neighbors, the mean lattice polarization is quite stable and remains close to zero over a wide temperature range that includes 37°C (310K). This raises new questions about the biophysical role of microtubules.

Materials with batch formula Pb_(1-x-3y/2)R_yBa_xNb₂O₆, where R=Y, (1-x)=0.73, 0.63, 0.53 and y=0.00, 0.02 have been prepared by the double sintering method. Substitution of yttrium (Y) restored tetragonal symmetry of PBN but reduced lattice parameters, cell volume and enhanced the density. Transition temperature of PBN has decreased due to the substitution of Y³⁺. Enhanced room temperature spontaneous polarization (P_s)=149.97 μC/sq. cm has been observed in PBN53, which is above MPB, whereas enhanced value of P_s=112.74 μC/sq. cm is found in Y: PBN63 at MPB region. The room temperature Pyroelectric coefficient (P_RT=1.07) has been observed in the composition where maximum volume of P_s is obtained. Similarly, enhanced values of piezoelectric coefficients K_p=0.244, K_t=0.353, K₃₁=0.131, d₃₁=60, d₃₃=159 and g₃₁=3.65 have also been found in the same material PBN53. Substitution of Yttrium enhanced the stiffness constant 13.59 in PBN 73 to 14.27 of Y: PBN73.

Samples of 0.65Pb(Mg_1/3Nb_2/3)O₃-0.35PbTiO₃ single crystal cut in three orientations <001>, <110>, <111> were supplied by H. C. Materials Corporation, Urbana, Illinois, U.S.A. The dielectric constant was first measured for these three samples with different orientations. It shows the samples are of high quality. Then we observed the hysteresis loops at different temperatures for these samples. From hysteresis loops we obtained the remnant polarization as a function of temperature. It is found that the remnant polarization changes with temperature rapidly in the temperature region from 80°C to 130°C. The displacement current without sustained applied electric field on it that is supposed to be proportional to the pyroelectric coefficient in different orientation was measured by a Picoammeter under no applied electric field and the comparison of the displacement current density with the pyroelectric coefficient was presented.

The pyroelectric and phase transition properties of a finite alternating ferroelectric superlattice with three surface layers are studied on the basis of the transverse Ising model by using the mean field approximation. The temperature-dependence of the polarization and pyroelectric coefficient of the superlattice with various inter-layer exchange interaction constants are given. The profiles of the polarization as well as the pyroelectric coefficient of the superlattice are shown. By taking into account the effects of the exchange interaction and transverse field parameters on the phase diagrams, we find that the phase transition properties of the superlattice are sensitive to the changes of transverse Ising model parameters.

This paper presents a new preparation scheme of monolithic pyroelectric thin film infrared sensor. The sensor can be prepared directly on readout circuit and its electrode can be connected to the readout circuit through a via. PbTiO₃ thin film is used as pyroelectric material. Porous SiO₂ thin film is applied onto silicon wafer to improve the thermal isolation of the pyroelectric layer. Copper interconnection is used in readout circuit to solve the problem that aluminium interconnection can't endure the annealing temperature of PbTiO₃ thin film.

Two-dimensional thermal analysis of multi-layer thin film pyroelectric infrared detectors is performed according to the structure and test conditions of detectors and the temperature distribution of detectors is obtained. Result shows that the insulation layer of multi-layer film pyroelectric infrared detector can effectively reduce thermal flow from pyroelectric layer substrate and the response of detector increases with the increasing of insulation layer thickness; when the thermal conductivity of insulation layer is lower than of air, its performance is better than micro-bridge structure.

We study the temperature effects on mobile charges in a thermopiezoelectric semiconductor plate through pyroelectric and thermoelastic couplings. The macroscopic theory of thermopiezoelectric semiconductors is used. A set of two-dimensional (2D) equations is derived for extension and bending with shear deformation of the plate. A few solutions are obtained. Numerical results show that the distribution of the mobile charges in the plate can be manipulated by the temperature field. In the case of temperature-induced uniform extension, a combination of physical parameters is identified which characterizes the strength of the coupling between the temperature field and the mobile charge distribution. The results obtained are fundamental to piezotronic devices involving temperature effects.

Pyroelectric composites of triglycine sulfate (TGS)-polyvinylidene difluoride (PVDF) doped with graphene are studied. It is found that the graphene can effectively improve the polling efficiency and thermal property of the composites so that the infrared detective performance can be significantly improved. For example, by adding about 0.83 wt.% of graphene, the infrared detective property can be improved by more than 30%. It is also found that the size of the graphene plays a critical role on the property improvement. For example, the small-sized graphene prepared by ultrasonic exfoliation (UE) method is more effective than the big-sized graphene prepared by electrochemical exfoliation (EE) method.