Static charge, phase separation

Existence of stripes looks just natural in terms of a static phase separation. At doping the system (LSCO) must screen the excess charge (Sr2+-ions) in AF regions. Therefore stripes of the AF ordered phase must alternate with "metallic domain walls. The stripe arrangement by itself is nothing but an optimization of the competing Coulomb and lattice forces [7]. (The phenomena is well known in physics of surface.)... 

The concept of equilibration of surface states at an interface may be illustrated by the case in which the two contacting phases are solids. In such a case, the energy levels of the surface state electron can be used to explain the surface state equilibration that occurs on contact. When two dissimilar surfaces contact each other, the transfer of surface state electrons occurs to equilibrate the energy levels of surface state electrons at the newly created interface. When two surfaces are separated, each surface retains the equilibrium electron level, which has been just attained on the contact, leading to the creation of the static charge, if a material is, or both materials are, nonconducting. In such a case, the two surfaces stick together by the coulombic attraction and it is necessary to apply force to separate them. 

A detailed description of the experimental apparatus and procedure used for the aqueous study are given elsewhere (Roop and Akgerman, Ind. Eng. Chem. R., in review) Static equilibrium extractions were carried out in a high pressure equilibrium cell (300 mL Autoclave). After the vessel is initially charged with 150 mL of water containing 6.8 wt.% phenol and supercritical carbon dioxide (and a small amount of entrainer, if desired), the contents were mixed for one hour followed by a two hour period for phase separation. Samples from both the aqueous phase and the supercritical phase were taken for analysis and the distribution coefficient for phenol calculated. 

A number of studies have focused on D-A systems in which D and A are either embedded in a rigid matrix [103-110] or separated by a rigid spacer with covalent bonds [111-118], Miller etal. [114, 115] gave the first experimental evidence for the bell-shape energy gap dependence in charge shift type ET reactions [114,115], Many studies have been reported on the photoinduced ET across the interfaces of some organized assemblies such as surfactant micelles [4] and vesicles [5], wherein some particular D and A species are expected to be separated by a phase boundary. However, owing to the dynamic nature of such interfacial systems, D and A are not always statically fixed at specific locations. 

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. 

The important thing to keep in mind is that whenever there is contact and separation of phases, a charge may develop that could be disastrous. Three conditions must be met before an explosion caused by static electricity can take place ... 

Gaseous hydrogen, containing a suspended second phase was found (as expected) to generate static (promote charge separation). This added to understanding of the need to avoid static inside purification systems where condensed oxidant phases could be in contact with H2. 

Important characteristics that describe static mass, conformations, and dimensions of polymer molecules have been surveyed. This has been followed by hydrodynamic properties such as diffusion and viscosity. A separate section has been used to describe the salient aspects of charged polymers and colloids in solution. From there, the collective properties of polymers were briefly introduced in terms of their solution thermodynamics, the relationship of these to the scattering of light, and to phase behavior and transitions. Concentrated polymer solutions and melts become extraordinarily complex, with time response behavior depending on polymer architecture and interactions, and this has been briefly discussed in the area of rheology. In the solid-state limit of rheology, polymers take on myriad applications in materials engineering applications, in electronics, optics, and other areas. 

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