Dipole moment effects

An efficient a-sialylation that took advantage of the highly reactive sialyl donors having C5 cyclic imides, especially phthalimide (NPhth), by virtue of the fixed-dipole moment effects, was also reported [42], For example, the use of the sialyl donor 4 and acceptor 6 at -78°C supplied the sialoside 7 as a only with 92% yield on 50 mg scale. The scale-up in batch process, however, significantly decreased the yield and stereoselectivity. This decrease in sialylation efficiency might be a result of... 

The dipole moment effects of halogen atoms are sizeable (though very similar because their electronegativity varies inversely with size) and they differ from those of such other simple groups as CH3, CF3 and CN (see Table 5). Dipole moment effects are important among those that influence the relative populations of conformers of a substance as a function of its physical state (solid, liquid, gas) or the presence of a solvent. 

The difficulty In distinguishing permanent dipole from Induced dipole moment effects In a molecular beam deflection... 

Soc. 74, 5693-8 (1952). UV, dipole moment effects of solvents, H bonding, phenol, ani-sole, aniline, dimethylaniline in heptane, CCl4, dioxane, ether. 

It is concluded that the life-time properties at initial phase were controlled by dipole moment differences of ETMs and great dipole moment materials can enhance initial luminance properties by means of strong dipole-dipole interactions among the molecules. In near future, it is expected to find out a general mechanism of dipole moment effect on life-time. 

Often it is desirable to employ a mixture with a high value of the dielectric anisotropy As in order to keep the threshold voltage low. Compounds with permanent dipoles at one end, such as the cyano group, tend to increase As, but in some cases such molecules tend to pair with anti-parallel dipole moments, effectively redircing As. For this reasort, non-polar compoimds are sometimes mixed with polar compoimds to achieve the desired properties. Depending on the type of display, the desired value of the bend elastic... 

According to Eq. 6, direct piezoelectricity can be separated into a matrix (or dipole-density) effect ( secondary piezoelectricity ) and a dipole-moment effect ( primary piezoelectricity ). The two alternative situations are illustrated in Figs. 3 and 4, respectively. However, if the matrix and dipole phases have the same elastic modulus (i.e., spring constant), no piezoelectricity is observed (affine deformation). This situation has been illustrated in the spring model of Fig. 2 above where the electrode eharges do not change upon deformation. 

Equation 7 includes the prediction that the ratio of the piezoelectric coefficient and the remanent polarization P3 = Pr should be approximately equal to the elastic compliance /Ym of the matrix phase for the dipole-density effect or to the elastic compliance HYd of the dipole phase for the dipole-moment effect, respectively (or inversely proportional to the respective elastic modulus). First results assembled from the literature and from our own experimental data on PVDF and on cellular-foam PP and tubular-channel FEP ferroelectrets (Altafim et al. 2009) are shown in Fig. 5 (Qiu et al. 2013, 2014). They provide experimental evidence that the direct piezoelectric thickness coefficient of polymer materials can indeed be roughly approximated by the product of the remanent polarization in the poled material and of its overall elastic compliance. Additional data from the literature on other... 

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