27,329 research outputs found
Letter from Martin W. Bates
No full textThis document is a letter from Martin W. Bates in Dover addressed to William Tharp, Esquire. Bates expresses regret for missing Tharp during his recent visit to Dover. He recounts that he departed Wilmington on the same morning as Tharp but was compelled to stay overnight in Smyrna. In the letter, Bates anticipates that Tharp would need to address certain matters and assures him that their mutual friends remain receptive to various ideas. Bates suggests that the convention question can be delicately approached to avoid offending anyone whose favorable opinion they value. On the reverse side are penciled equations, Tharp's name, and his approximate location near Milford, Delaware. Bates' name appears twice along the bottom and again perpendicular to Tharp's details on the left
Letter from Martin W. Bates
No full textThis document is a letter from Martin W. Bates in Dover addressed to William Tharp, Esquire. Bates expresses regret for missing Tharp during his recent visit to Dover. He recounts that he departed Wilmington on the same morning as Tharp but was compelled to stay overnight in Smyrna. In the letter, Bates anticipates that Tharp would need to address certain matters and assures him that their mutual friends remain receptive to various ideas. Bates suggests that the convention question can be delicately approached to avoid offending anyone whose favorable opinion they value. On the reverse side are penciled equations, Tharp's name, and his approximate location near Milford, Delaware. Bates' name appears twice along the bottom and again perpendicular to Tharp's details on the left
Sanford Bates Correspondence from Martin Littlefield
No full textA letter and contract from Martin Littlefield addressed to Sanford Bates
Sanford Bates Correspondence from Martin Littlefield Letter
No full textA letter addressed to Sanford Bates from Martin Littlefield
Modelling the chemically induced liquid crystalline phases in mixtures of disc-shaped mesogens: the phase diagram of quadrupolar Gay-Berne discs revisited
No full textWe investigate the phase behaviour of pure systems and mixtures of quadrupolar Gay-Berne discs. The interaction potential mimics that of disc-shaped molecules which exhibit chemically induced phases with a structure based on columns of alternately stacking species. The phase diagram of the pure system is determined over a range of pressures, and the phase sequence is shown to include tilted columnar and nematic phases. The mixtures, in which the species have equal but opposite quadrupole moments, are investigated over a range of pressures using semigrand canonical simulations, such that the composition of the system is allowed to change. The fact that the composition is not fixed is especially important at the phase transitions, where the compositions of the coexisting phases may not necessarily be the same. In this situation, preparation of a system in the 'biphasic region' will lead to phase separation into the two distinct phases of differing compositions. The resulting phase diagram obtained using semigrand canonical simulations indicates that the columnar nematic phase observed in previous fixed composition simulations of this model [Liq. Cryst., 24, 229 (1998)] is not stable with respect to phase separation into an isotropic phase rich in a single component and a hexagonal columnar phase composed of roughly equal quantities of the two components. The structure of the columnar phase for the mixture is shown to be based on the alternate stacking of the different species. The relative concentrations of the different species in this phase may deviate up to approximately 60 : 40 mol %, after which any further material added will separate into the pure isotropic state
Coarse grained models for flexible liquid crystals: parameterization of the bond fluctuation model
No full textWe extend the bond fluctuation model, originally devised to investigate polymer systems, to contain anisotropic interactions suitable for the simulation of large flexible molecules such as liquid crystalline polymers and dendrimers. This extended model coarse grains the interaction between the flexible chains at a similar level of detail to the mesogenic units. Suitable interaction parameters are obtained by performing trial simulations on a low molar mass liquid crystalline system. The phase diagram of this system is determined as a function of the molecular stiffness. The nematic to isotropic transition temperature is found to increase with increasing stiffness
Computer simulation study of the phase behavior of a nematogenic lattice-gas model
No full textThe phase behavior of a mesogenic lattice-gas model consisting of freely rotating spins located at the sites of a three-dimensional cubic lattice has been studied using grand canonical Monte Carlo simulations. When two neighboring sites are occupied, the spin vectors interact via the extensively studied anisotropic Lebwohl-Lasher potential, plus an isotropic term of variable strength. The interaction between occupied and empty sites and two empty sites is taken to be zero. If the parameter governing the strength of the isotropic term is zero, the model exhibits an isotropic fluid-nematic transition, which becomes increasingly stronger as the temperature is lowered. The additional isotropic term is found to be important if the model is to reproduce experimental phase behavior, that is, to exhibit both nematic-vapor coexistence at low temperature and isotropic-vapor coexistence at higher temperatures
Phase behavior and free interfaces of a lattice-gas nematic-liquid-crystal model
No full textThe phase behavior of a mesogenic lattice-gas model consisting of molecules located at the sites of a three-dimensional cubic lattice has been studied using grand canonical Monte Carlo simulations. When two neighboring sites are occupied, the molecules interact via a potential composed of an isotropic lattice-gas (LG) term and an anisotropic Humphries-Luckhurst-Romano (HLR) term [Mol. Phys. 42, 1205 (1981)]. The LGHLR model is shown to exhibit either nematic-isotropic, nematic-vapor (NV), and isotropic-vapor (IV) coexistence or just nematic-isotropic fluid coexistence, depending on the strength of the isotropic term. The liquid-vapor (i.e., NV and IV) interfaces were studied using canonical Monte Carlo simulations. By controlling the strength of the term that governs the anisotropy in the attractive forces, either planar or homeotropic anchoring is observed at the NV interface. The temperature dependencies of the density and order parameter profiles across the interfaces are determined for these two anchoring geometries
Martin Waltham Bates
No full textThis negative shows a painting by Ethel Pennewill Brown Leach of Martin Waltham Bates, who was a United States Senator from 1838 to 1848
Martin Waltham Bates
No full textThis negative shows a painting by Ethel Pennewill Brown Leach of Martin Waltham Bates, who was a United States Senator from 1838 to 1848
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