Field, Leslie

For very high magnitude fields Leslie [171, 174] makes a reasonable approximation to the function 0q(z) by simply setting... 

Dr. Leslie Crombie, an honor professor, was awarded an international prize in the field of agricultural pesticides at the American Chemical Society, held on August 24, 1998, in Boston. At the memorial symposium, Katsuda [1] presented a lecture. 

In a weak flow field, Eq. (64) can be rewritten in a form similar to that for the direct n appearing in Leslie and Ericksen s phenomenological theory [160—163] for nematic systems. Thus, we have... 

The three elastic constants are the Frank elastic constants, called after Frank, who introduced them already in 1958. They originate from the deformation of the director field as shown in Fig. 15.52. A continuous small deformation of an oriented material can be distinguished into three basis distortions splay, twist and bend distortions They are required to describe the resistance offered by the nematic phase to orientational distortions. As an example, values for Miesowicz viscosities and Frank elastic constants are presented in Table 15.10. It should be mentioned that those material constants are not known for many LCs and LCPs. Nevertheless, they have to be substituted in specific rheological constitutive equations in order to describe the rheological peculiarities of LCPs. Accordingly, the viscosity and the dynamic moduli will be functions of the Miesowicz viscosities and/or the Frank elastic constants. Several theories have been presented that are more or less able to explain the rheological peculiarities. Well-known are the Leslie-Ericksen theory and the Larson-Doi theory. It is far beyond the scope of this book to go into detail of these theories. The reader is referred to, e.g. Aciemo and Collyer (General References, 1996). 

Leeds most famous chemical alumna was May Sybil Leslie.60 Leslie was born on 14 August 1887 in Yorkshire and studied chemistry at the University of Leeds. She graduated with first class honours in 1908, and was awarded an M.Sc. for research with Harry M. Dawson01 the following year on the kinetics of the iodination of acetone, work that has since become a classic in its field.62 In that same year, 1909, Leslie was awarded a scholarship, which she decided to use to work with Marie Curie63 in Paris. Her letters from Paris to Smithells are among the few accounts of life in the early Curie laboratory.04... 

As Er is increased further to around 10 in 8CB (at 37°C), there is a roll-cell instability involving (a) a periodic modulation of the director field in the vorticity direction and (b) a cellular flow. The rolls cells are parallel to the primary flow direction (Pieranski and Guyon 1974) (see Fig. 10-19). These transitions in the director field have been both predicted from the Leslie-Ericksen theory (Manneville and Dubois-Violette 1976 Larson 1993) and... 

Because of the difficulty with which polymeric nematic monodomains are prepared, there are few measurements of Leslie viscosities and Frank constants for LCPs reported in the literature. The most complete data sets are for PBG solutions, reported by Lee and Meyer (1990), who dissolved the polymer in a mixed solvent of 18% dioxane and 82% dichloromethane with a few percent added dimethylformamide. Some of these data, measured by light scattering and by the response of the nematic director to an applied magnetic field, are shown in Figs. 11-19 and 11-20 and in Table 11-1. While the twist constant has a value of around K2 0.6 x 10 dyn, which is believed to be roughly independent of concentration and molecular weight, the splay and bend constants ATj and K3 are sensitive to concentration and molecular weight. 

Few other sets of viscosities exist for polymeric nematics. Yang and Shine (1993) obtained three of the Leslie viscosities for monodomains of poly(n-hexyl isocyanate) (PHIC) from rheological measurements in the presence of an electric field, and they obtained values reasonably consistent with the predictions of the Kuzuu-Doi expressions. From monodomains of the polyion PBZT, poly(l,4-phenylene-2,6-benzobisthiazole) in methane sulfonic acid, some of the Leslie-Ericksen parameters have been extracted via light-scattering and magnetic-field-reorientation studies (Berry 198S Srinivasarao and... 

The tendency of LCs to resist and recover from distortion to their orientation field bears clear analogy to the tendency of elastic solids to resist and recover from distortion of their shape (strain). Based on this idea, Oseen, Zocher, and Frank established a linear theory for the distortional elasticity of LCs. Ericksen incorporated this into hydrostatic and hydrodynamic theories for nematics, which were further augmented by Leslie with constitutive equations. The Leslie-Ericksen theory has been the most widely used LC flow theory to date. 

Leslie recognized from early experiments that the anisotropy of the materials calls for multiple viscosity coefficients corresponding to different orientation of the LC relative to the flow. Combining this idea with the Ericksen theory leads to the Leslie-Ericksen (LE) theory, which comprises two elements one describing the evolution of n(r) in a flow field, and the other prescribing an extra stress tensor due to the evolving (r) field. 

George A. Olah G.K. SuRYA Prakash Robert E. Williams Leslie D. Field Kenneth Wade... 

API Research Project 42. API Research Project 42 was established in 1940 at The Pennsylvania State College with Frank C. Whitmore as Director, and Leslie C. Beard, Jr., Socony-Vacuum Oil Co., Inc., as Chairman of the Advisory Committee. Its basic objective is to prepare pure hydrocarbons in the lubricating oil range. Further objectives are to develop new synthesis and purification methods for these hydrocarbons, to determine physical properties of the hydrocarbons prepared, and to develop correlations between hydrocarbon structure and physical properties. After the death of Dean Whitmore in 1947, his assistant, Robert W. Schiessler, was appointed Director of the project. Schiessler has proven to be an able and fitting successor to Whitmore, whose work in this field was outstanding. 

Battersby, D.G. (1976) Cooper Basin oil and gas fields. In Economic Geology of Australia and New Guinea. 3 (Eds Leslie, R.B., Evans, H.J. Knight, C.L.), Petrol. Australasia Inst. Mineral. Metal., 7, 321-370. 

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