Kent State University

About: Kent State University is a education organization based out in Kent, Ohio, United States. It is known for research contribution in the topics: Liquid crystal & Population. The organization has 10897 authors who have published 24607 publications receiving 720309 citations. The organization is also known as: Kent State & KSU.

Bragg reflection from cholesteric liquid crystals.

Abstract: In this paper we discuss the optical reflective properties of single and multidomain cholesteric liquid crystals both experimentally and theoretically. The multidomain system has been prepared by dispersing a low concentration of polymer in a cholesteric liquid crystal. This results in a (passive) bistable colorful reflective display. Here we discuss the role of the polymer in altering the reflective properties in regard to their spectra and viewing characteristics. Theoretically we offer an application of the well known Berreman method [J. Opt. Soc. Am. 62, 502 (1972)] suitable for systems composed of an ensemble of uncorrelated domains, each of which is composed of the same dielectric anisotropy, however with its own local orientation. Using this technique the reflective properties of a cholesteric liquid crystal possessing a distribution in the orientation of the helix axes are simulated. We furthermore illustrate how a small fluctuation in the pitch from one domain to another significantly reduces any interference fringes. From these simulations we will show how experimentally by using a polymer network one may control the extent to which the orientation of the helix axes are distributed.

Nickel ferrocyanide as a high-performance urea oxidation electrocatalyst

Abstract: Urea is often present in waste water but can be used in powering fuel cells and as an alternative oxidation substrate to water in an electrolyser. However, an insufficient mechanistic understanding and the lack of efficient catalysts for the urea oxidation reaction have hampered the development of such applications. Here we demonstrate that a nickel ferrocyanide (Ni2Fe(CN)6) catalyst supported on Ni foam can drive the urea oxidation reaction with a higher activity and better stability than those of conventional Ni-based catalysts. Our experimental and computational data suggest a urea oxidation reaction pathway different from most other Ni-based catalysts that comprise NiOOH derivatives as the catalytically active compound. Ni2Fe(CN)6 appears to be able to directly facilitate a two-stage reaction pathway that involves an intermediate ammonia production (on the Ni site) and its decomposition to N2 (on the Fe site). Owing to the different rate-determining steps with more favourable thermal/kinetic energetics, Ni2Fe(CN)6 achieves a 100 mA cm−2 anodic current density at a potential of 1.35 V (equal to an overpotential of 0.98 V). Urea oxidation could be a lower-energy alternative to water oxidation in hydrogen-producing electrolysers, but improved catalysts are required to facilitate the reaction. Geng et al. report nickel ferrocyanide as a promising catalyst and suggest that it operates via a different pathway to that of previous materials.

Balancing Parent Care With Other Roles Interrole Conflict of Adult Daughter Caregivers

Abstract: This study examined interrole conflict experienced by 278 women who simultaneously occupied 4 roles: parent care provider, mother to children at home, wife, and employee. Compared with women who experienced no conflict between parent care and their other roles, women reporting parent care conflict tended to have fewer socioeconomic resources, to have older children, and to be caring for parents with greater impairment. Women who reported conflicts between parent care and employment were older; had more education; had marriages of longer duration; and had older, more self-sufficient children than women who reported conflict between the parent care role and the mother role. Some evidence was found for the hypothesis that interrole conflict between parent care and other roles mediates the relationship between parent care stress and psychosocial well-being. Results suggest that one way parent care stress exerts its deleterious effects on the well-being of adult daughters is through the incompatible pressures of parent care and other roles.

Large Bulk Photovoltaic Effect and Spontaneous Polarization of Single-Layer Monochalcogenides.

Abstract: We use a first-principles density functional theory approach to calculate the shift current and linear absorption of uniformly illuminated single-layer Ge and Sn monochalcogenides We predict strong absorption in the visible spectrum and a large effective three-dimensional shift current ($\ensuremath{\sim}100\text{ }\text{ }\ensuremath{\mu}\mathrm{A}/{\mathrm{V}}^{2}$), larger than has been previously observed in other polar systems Moreover, we show that the integral of the shift-current tensor is correlated to the large spontaneous effective three-dimensional electric polarization ($\ensuremath{\sim}19\text{ }\text{ }\mathrm{C}/{\mathrm{m}}^{2}$) Our calculations indicate that the shift current will be largest in the visible spectrum, suggesting that these monochalcogenides may be promising for polar optoelectronic devices A Rice-Mele tight-binding model is used to rationalize the shift-current response for these systems, and its dependence on polarization, in general terms with implications for other polar materials