Stripe period

Figure 8.6 Stripe period as a function of temperature for various thickness PbTiOs films, showing transition between Fa and h p stripe phases.

Figure 8.7 Upper plot Ferroelectric transition temperature versus film thickness. Lower plot Stripe period versus film thickness. Diamonds phase Fp at T = Tc — 250 K. Triangles phase Fa at T = TC — 50 K. Lines fits to parabolic dependece.

The evolution of domain patterns may develop in a different way domains could disappear when the time or voltage interval of their existence is exceeded. It is also possible to observe a drastic decrease in the stripe period with the voltage. In the latter case, the domain pattern cannot be easily driven to the turbulent state. 

Pereira and Williams performed early ID large-area simulations of a symmetric AB diblock film on surfaces patterned with selective stripes where the stripe period was either shorter or longer than the lamellar period. At the same time, Chen and Chakrabarti carried out full 3D simulations of a symmetric AB diblock on a striped surface, observing strong epitaxial order when the stripe and polymer periods match but an onset of tilted lamellae for significantly longer period stripes. Kielhom and Muthukumar carried out early 3D simulations of a thick symmetric diblock film in the... 

Unlike catfish, tilapia, trout and salmon, that produce several hundred to several thousand eggs per female, many marine species produce large numbers of very small eggs. Hundreds of thousands to millions of eggs are produced by such species as haUbut, flounders, red dmm, striped bass, and shrimp. Catfish, salmon, and trout spawn once a year, while tilapia and some marine species spawn repeatedly if the proper environmental conditions are maintained (1). Red dmm, for example, spawn every few days for periods of several months when light and temperature and properly controlled (10). 

Qi, H. and Hegmann, T. (2006) Formation of periodic stripe patterns in nematic liquid crystals doped with functionalized gold nanopartides. Journal of Materials Chemistry, 16, 4197-4205. 

Recently it has been reported that even colloidal particle suspensions themselves, without added polymers, can form dissipative structures. Periodic stripes of colloidal particles (monodisperse particles of diameter 30 nm and 100 nm, respectively) and polystyrene particles (monodisperse diameters from 0.5 to 3 pm) can be formed from dilute aqueous suspensions. The stripes are parallel to the receding direction of the edge of the suspension droplet and thus indicate that a fingering instability... 

A very different model of tubules with tilt variations was developed by Selinger et al.132,186 Instead of thermal fluctuations, these authors consider the possibility of systematic modulations in the molecular tilt direction. The concept of systematic modulations in tubules is motivated by modulated structures in chiral liquid crystals. Bulk chiral liquid crystals form cholesteric phases, with a helical twist in the molecular director, and thin films of chiral smectic-C liquid crystals form striped phases, with periodic arrays of defect lines.176 To determine whether tubules can form analogous structures, these authors generalize the free-energy of Eq. (5) to consider the expression... 

These results were extended by Tilton et a/.(n8) to adsorption of eosin-labeled BSA on polymer surfaces. They also found a component that surface diffuses, with coefficients ranging from 1.2 x 10 9 to 2.6 x 10 9cm2/s, depending on surface type. In this study, intersecting TIR laser beams rather than a focused stripe were used to define the spatial intensity variation. Surface diffusion was even noted for the most irreversibly adsorbed eosin-labeled BSA components this was evident on samples rinsed for long periods with unlabeled BSA after exposure to eosin-labeled BSA. The surface diffusion coefficient of the irreversibly bound BSA was found to be a strong function of adsorbed concentration.(n9)... 

Note 1 The nematic liquid crystal must have a negative dielectric anisotropy (Af < 0), and a positive anisotropy (Aa > 0). The optical texture corresponding to the flow pattern consists of a set of regularly spaced, black and white stripes perpendicular to the initial direction of the director. These stripes are caused by the periodicity of the change in the refractive index for the extraordinary ray due to variations in the director orientation. 

An unusual feature of the cuprate superconductors is the anomalous suppression of superconductivity in La2 Ba Cu04 and related phases when the hole concentration X is near 1/8. A possible explanation is a dynamical modulation of spin and charge giving antiferromagnetic stripes of copper spins periodically separated from the domains of holes. Neutron-diffraction evidence has been presented in the case of Laj g Nd() Sr CuO (x = 0.12) which is a static analogue of the dynamical stripe model (Tranquada et al., 1995). It appears that spatial modulations of spin and charge density are related to the superconductivity in these oxides. 

Fig. 8 (a) Schematic representation of the structure of the chiral nematic phase of DNA, showing continuously twisting nematic layers, giving rise to a p/2 periodicity easily observable in the side view on the left, (b) N droplets observed in polarized microscopy. The bright and dark stripes correspond to p/2 (size bar is 10 pm). Adapted with permission from [27]... 

The calculation of a Feshbach shape resonance has been carried out for a 2D superlattice of carbon nanotubes of period Ap on a 2D x,y plane shown in Fig. 4. The electronic structure is similar to the case of a superlattice of stripes [93-96,102] and this type of heterostructures at atomic limit can be classified as superlattices of quantum wires". While the charge carriers move as free charges in the x direction, the wire direction, they have to overcome a periodic potential barrier V(x,y), with period Ap, amplitude Vb... 

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