Display bistable

Heintz RA, Zhao H, Ouyang X, Grandinetti G, Cowen J, Dunbar KR (1999) New insight into the nature of Cu(TCNQ) solution routes to two distinct polymorphs and their relationship to crystalline films that display bistable switching behavior. Inorg Chem 38 144—156... 

However, in many cases the fluctuating systems of interest are far from thermal equilibrium. Examples include optical bistable devices [45], lasers [23,46], pattern forming systems [47], trapped electrons that display bistability and switching in a strong periodic field [48-50], and spatially periodic systems (ratchets) that display a unidirectional current when driven away from thermal equilibrium [51-56]. 

Recently, a non-volatile digital memory device was fabricated using PANI nanofiber (diameter ca. 30 nm) decorated with gold nanoparticles (diameter below 5 nm) [317]. As shown in Fig. 7a, the polymer memory device displayed bistable electrical behavior (ON/OFF states). The transition from the OFF state to the ON state was ascribed to an electric field-induced charge transfer between the PANI nanofibers and the gold nanoparticles. The write-read-erase cycle tests could also be performed more than seven times (Fig. 7b). 

Systems consisting of a low molar mass liquid crystal and a polymer are currently of great interest with respect to applications and due to the intriguing finite size effects. This chapter describes some aspects of liquid crystals embedded in dense polymer binders and low concentration polymer networks that modify the bulk liquid crystal phase, with added emphasis on chirality. The introduction to the phenomenological description is followed by the modeling of field effected chiral nematic droplets in polymer-dispersed liquid crystal systems. Next the orientational ordering induced by polymer networks is described, and finally the usefulness of these materials for direct-view reflection displays, bistable displays, and light valves is reviewed. 

Fixed points are not the only possible states of dissipative, far-from-equilibrium systems more complex macroscopic attractors, like limit cycles or even strange attractors, are commonly observed [19]. Bistabilities between the different attractor types may occur and give rise to interesting transition rate processes when these systems are subjected to external noise. We examine some of the new features that enter the calculation of the transition rate by examining some specific examples of systems displaying bistability between a fixed point and a limit cycle, but the discussion can be generalized to other situations. 

Positive feedback is also involved in the control of cdc2 by reversible phosphorylation. Thus, cdc2 activates the phosphatase cdc25, which catalyzes the dephosphorylation and concomitant activation of the kinase cdc2. The model based on negative feedback in cyclin-cdc2 interactions can be extended to take this positive feedback into account. Sustained oscillations can be obtained in these conditions [31, 134], but the waveform of cdc2 in the course of oscillations now displays a plateau. This plateau is due to the occurrence of a phenomenon of bistability, which is accompanied by hysteresis, as... 

A typical chemical system is the oxidative decarboxylation of malonic acid catalyzed by cerium ions and bromine, the so-called Zhabotinsky reaction this reaction in a given domain leads to the evolution of sustained oscillations and chemical waves. Furthermore, these states have been observed in a number of enzyme systems. The simplest case is the reaction catalyzed by the enzyme peroxidase. The reaction kinetics display either steady states, bistability, or oscillations. A more complex system is the ubiquitous process of glycolysis catalyzed by a sequence of coordinated enzyme reactions. In a given domain the process readily exhibits continuous oscillations of chemical concentrations and fluxes, which can be recorded by spectroscopic and electrometric techniques. The source of the periodicity is the enzyme phosphofructokinase, which catalyzes the phosphorylation of fructose-6-phosphate by ATP, resulting in the formation of fructose-1,6 biphosphate and ADP. The overall activity of the octameric enzyme is described by an allosteric model with fructose-6-phosphate, ATP, and AMP as controlling ligands. 

In the experiments we have used two approaches. First, we have simulated the kinetics of a bistable optical system in the Debye relaxation appoximation for different forms of potential by means of electronic analog simulation. Secondly, we have investigated the kinetics of a double-cavity membrane system (DCMS) driven by two modulated laser beams at different wavelengths. This system is known to display optical bistability [111]. 

Typical bistable species are the so-called photochromic compounds molecules that can be reversibly interconverted, with at least one of the reactions being induced by light excitation, between two forms displaying different absorption spectra.17 8 ... 

The formaldehyde-sulfite reaction displays non-linear dynamics it is a clock reaction with a sudden pH excursion (from ca 7 up to ll).280 The induction period in batch processes is explained by the internal buffer systems, HS03 -S03. However, flow reactors also exhibit pH oscillations and bistability. 

Grauel and Krischer also detected similar stationary domains during the oxidation of H2 on a Pt ring electrode in sulfuric acid [182]. As can be seen in the cyclic voltammogram in Fig. 46a, in this case the homogeneous active branch coexisted with the oxide covered passive branch, and thus the homogeneous dynamics were bistable. The stationary structure displayed in Fig. 46b spontaneously formed when a... 

Fig. I. Schematic diagrams of the contrast versus the applied field for (a) a twisted nematic, (b) a cholesteric guest-host bistable display (Wysocki ei al., 1972 Ohtsuka and Sukamoto, 1973), and (c) a bistable LCD (Boyd et al., 1982).

The third electro-optical effect using calamitic nematic liquid crystals makes use of a flexoelectric effect manifested by a curved asymmetrical nematic medium. This corresponds to piezoelectricity in crystals. The existence of flexoelectricity in a nematic phase under certain boundary conditions was predicted in the late 1960s and then confirmed experimentally several years later. However, LCDs using this effect, such as bistable nematic displays are only in the development stage and as such they will not be discussed in this monograph. 

In principle, this mode of operation creates the possibility of producing high-information-content displays due to the short frame times associated with bistable displays, since they are basically a memory effect and only new information must be changed. Unfortunately, metastable twist states of intermediate twist, which degrade the optical performance of the device, form around dust particles in cells with a cell gap below a certain value (d < 20 m). Therefore, since the response time is proportional to d, very long response times are observed ( 1 s) for LCDs with a cell gap above this critical value. These optically disruptive metastable twist states also form at the interface with spacers used to generate a uniform cell gap. 

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