Investigating nano-structured domains within ionic liquids: the effect of cation change on thermal equilibrium and relaxation of spiropyran and spirooxazine.

The established belief that ionic liquids (ILs) behave as homogenous solvents such as that observed in molecular solvents has been challenged.1, 2 Previous use of solvatochromic probe dyes has allowed for the traditional parameter of ‘polarity’ to be determined.3 These values were compared to the kinetics of the photochromic spirocyclic compounds spirooxazine (SO) and spiropyran (SP). The nature of SO substituents limit the ability of hydrogen bond formation and so relies primarily on electrostatic interactions with the solvent system. Such an increase in solute freedom would be expected to increase the ability of the molecules to dissociate and migrate within the solvent system. A polarity-kinetic relationship for spirocyclic compounds has been established in molecular solvents with increasing polarity exhibiting decreased rates of thermal relaxation from the coloured merocyanine (MC) form to the spiro (SO/SP) form.4 However, thermal relaxation of SO in ionic liquids fails to present a correlation between polarity and kinetics. Kinetic studies were further enhanced by analysis of the relaxation process using thermodynamic parameters of activation. Previous studies have (primarily molecular modelling) proposed that ionic liquids possess a structured in-homogenous structure containing distinct areas of polar and non-polar regions.5 The probe dyes used to examine parameters such as hydrogen bonding (Kamlet-Taft) and polarity (ET30) may only examine a particular region in the solvent. This means that the probe molecules may solvate in one region while compounds such as SO may interact in another region completely and therefore not allow for correlation of polarity to thermal relaxation rates observed. The closed form is a neutral compound exhibiting non-polar characteristics. MC, due to its zwitterionic nature, is in contrast highly polar. We believe that the size and ratio of polar to non-polar regions may be a critical factor in the process of SO thermal relaxation. Increasing non-polar regions may encourage the SO form by shifting equilibrium and encouraging migration and facilitate enhanced closure of MC within the solvent system. Thermal relaxation of SO may therefore allow for confirmation of the theory of IL structuring. Due to the large range of ILs possible, a correlation in structural effects and a quantifiable change may aid in a more detailed understanding of ILs and facilitate customisability of the liquids to meet specific polarity/solvation requirements

Federal incentives for industrial modernization: Historical review and future opportunities

Concerns over the aging of the U.S. aerospace industrial base led DOD to introduce first its Technology Modernization (Tech Mod) Program, and more recently the Industrial Modernization Incentive Program (IMIP). These incentives include productivity shared savings rewards, contractor investment protection to allow for amortization of plant and equipment, and subcontractor/vendor participation. The purpose here is to review DOD IMIP and to evaluate whether a similar program is feasible for NASA and other non-DOD agencies. The IMIP methodology is of interest to industrial engineers because it provides a structured, disciplined approach to identifying productivity improvement opportunities and documenting their expected benefit. However, it is shown that more research on predicting and validating cost avoidance is needed

Investigating nano-structuring within imidazolium ionic liquids: A thermodynamic study using photochromic molecular probes

Following previous studies involving the thermal relaxation of spirocyclic compounds we extended our studies to investigate the formation of nano-structured domains in ionic liquids (ILs). Two compounds, spiropyran (BSP) and spirooxazine (SO) were added to imidazolium cation based ionic liquids with increasing chain lenghts (C2 –C12). Increasing side-chain length was found to have only minor effects on the rate of thermal relaxation of BSP and SO. BSP was found to be a suitable probe molecule as linear correlations in parameters were observed for this compound. This is believed to be due to the fact that BSP-IL interactions were based on hydrogen bonding between MCBSP and the cation compared to MCSO which is limited to electrostatic interactions thus enhancing the sensitivity of MCBSP to the charged polar regions. Increasing the side-chain of the cation resulted in slight increases in MC-BSP activation energy from 96.93 kJ.mol-1 in [C4mIm][NTf2] to 105.27 kJ.mol-1 in [C12mIm][NTf2]. MC-BSP S‡ and H‡ values also increased with increasing side-chain. Expansion and dispersion of polar regions due to increasing non-polar interactions may be enhanced by introduction of the bulky probe molecule. The resulting reorganisation of the system produced positive entropies of activation, 13.79 J.K- 1.mol-1 for C4mIm to 46.15 J.K-1.mol-1 for C12mIm, following an increase in disorder due to probe dye closure from MC to BSP and migration of dye to regions of preferential solvation. The ability for spirocyclic compounds to form both polar and non-polar isomers resulted in the ability to analyse both solvent regions using a single probe dye. Ground state equilibrium, Ke, examined non-polar regions of the IL while equilibrium of activation, K‡, examined the polar regions. A linear response to side chain length to equilibrium of activation was believed to be due to the fact that polar regions were possibly expanding due to increasing influence of non-polar side chain interactions upon the over solvent structure. The result of such reordering and dispersion of polar regions reduces solvent-solute interactions which increases rate of MC-BSP relaxation

Effective Use of Pastures for Horses

Pastures can serve two very necessary functions for the care and maintenance of horses. Not only do these areas of grasses and legumes provide a place for the horse to exercise, they can provide a significant portion of the horse’s nutrient requirement. Horses evolved as a grazing animal, so it is reasonable that many classes of horse can be adequately maintained on well-managed pastures

Pastures for Horses: Challenges and Opportunities

Horses were born to eat grass and how they evolved has allowed them to be efficient users of a high forage diet. In fact, for many of today’s horses, they will survive and thrive on an all forage diet