Polarity switch

The methyl substitution at a-position leads to an increase of the reactivity of styrene during polymerization as well as EDA-complex formation. However, the methyl substitution in p-position achieves an opposite effect. The strengthened complex formation connected with a further increase of the HOMO is faced with a drastically decreased polymerization rate. This can be explained by the well known steric effect of group hindrance around the p-C-atom under attack 72), as well as the polarity switch in the vinyl double bond. The p-C-atom in the p-methyl styrene possesses a... 

The p indicates symmetry-antisymmetry of the Legendre coefficient with respect to a light polarization switch, E indicates the response to an enantiomer switch. 

US patent 6,759,521, Polarization switching to control crystal form [113]. This patent describes a method to select and prepare polymorphs of materials by switching the polarization state of light and employing non-photochemical laser-induced nucleation. 

Klinke, C. Chen, J. Afzali, A. Avouris, P. 2005. Charge transfer induced polarity switching in carbon nanotube transistors. Nano Lett. 5 555-558. 

Most systems are equipped with power supplies that can be operated in constant voltage, constant current, and constant power modes. Common limits are 30 kV and 300 liA for constant voltage and constant current, respectively. Software-controlled polarity switching and programmable gradients are conveniences. 

C. Canalias, J. Hirohashi, V. Pasiskevicius, and F. Laurell, Polarization switching characteristics of flux grown KTi0P04 and RbTi0P04 at room temperature, Applied Physics Letters (submitted), (2005). 

Tolonen, A. and Uusitalo, L, Fast screening method for the analysis of total flavonoid content in plants and foodstuffs by high-performance liquid chromatography/electrospray ionization time-of-flight mass spectrometry with polarity switching. Rapid Commun. Mass Spectrom., 18, 3113, 2004. 

A method is described for extraction and determination of sildenafil citrate and its metabolites in human serum by micellar electrokinetic capillary chromatography (MEKC) coupled with sample stacking and polarity switching <2002JCH279>. 

In the work by Willemsen and co-authors [84] the three Stokes polarization parameters were studied during polarization switches in a vertical-cavity semiconductor laser. It was demonstrated that when the linear part of the absorptive anisotropy is close to zero [127], the laser is bistable and switches stochastically between two polarisations [128]. The analysis of large fluctuations of polarizations in this system [84] reveals what authors have called a stochastic inversion symmetry (see Fig. 10), which is analogous to the time-reversal symmetry observed for the model (17) and shown in Fig. 7. 

Figure 10. Time-resolved measurements of a very large polarization fluctuation, where the size of the fluctuation is about half (in fact, 45%) of that of a complete polarization switch [84],, V, , v2 and Si are the normalized Stokes parameters representing the polarization state on the Poincare sphere [84],...

As briefly mentioned in the Introduction, the extensive flow of chirality-related topics has been initiated by the discovery of polar switching in bent-core mesogens [11, 45]. Among the first banana smectic phases B1-B8, at least the B2 [10], B4 [14], and B7 [15] phases can be chiral. The chirality in the B2 phase was... 

Guo L, Dhara S, Sadashiba BK, Radhika S, Pratibha R, Shimbo Y, Araoka F, Ishikawa K, Takezoe H (2010) Polar switching in the smectic-A PA phase composed of asymmetric bent-core molecules. Phys Rev E 81 011703-1-6... 

Williams, J. P., Lock, R., Patel, V. J., and Scrivens, J. H. (2006). Polarity switching accurate mass measurement of pharmaceutical samples using desorphon electrospray ionizabon and a dual ion source interfaced to an orthogonal acceleration hme-of-flight mass spectrometer. Anal. Chem. 78 7440-7445. 

Garetz, B. A., Malic, J., Myerson, A. S., Polarization switching of crystal structure in the nonphotochemical light-induced nucleation of supersaturated aqueous glycine solutions. Phys. Rev. Lett. 2002, 89. 

Figure 1.27 Polarization switching current of TGBF single crystal with decreasing electrical field.

During polarization switching, the current response of the undoped film clearly shows a typical Curie-von-Schweidler behavior... 

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