No abstract

It is well documented that grain feeding stimulates adipogenesis in beef cattle, whereas pasture feeding depresses the development of adipose tissues, including intramuscular (i.m.) adipose tissue. Additionally, production practices that depress adipocyte differentiation also limit the synthesis of MUFA. Marbling scores and MUFA increase in parallel suggesting that stearoyl-coenzyme A desaturase (SCD) gene expression is closely associated with and necessary for marbling adipocyte differentiation. Similarly, marbling scores and fatty acid indices of SCD activity are depressed in response to dietary vitamin A restriction. In bovine preadipocytes, vitamins A and D both decrease glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, whereas incubation of bovine preadipocytes with l-ascorbic acid-2-phosphate increases GPDH activity. Exposing bovine preadipocytes to zinc also stimulates adipogenesis, putatively by inhibiting nitric oxide (NO) production. However, incubation of bovine preadipocytes with arginine, a biological precursor of NO, strongly promotes differentiation in concert with increased SCD expression. This suggests that the effect of either arginine or zinc on adipogenesis is independent of NO synthesis in bovine preadipocytes. Enhanced expression of SCD is associated with a greater accumulation of MUFA both in bovine preadipocyte cultures and during development in growing steers. In bovine preadipocytes, trans-10, cis-12 CLA strongly depresses adipocyte differentiation and SCD gene expression, thereby reducing MUFA concentrations. The bovine preadipocyte culture studies suggest that any production practice that elevates vitamins A or D or trans-10, cis-12 CLA in bovine adipose tissue will reduce i.m. adipose tissue development. Conversely, supplementation with vitamin C or zinc may promote the development of i.m. adipose tissue.

No abstract

Water solubility of PEDOT:PSS conducting polymer is achieved by PSS at the expense of disturbing the crystallinity and electron mobility of PEDOT. Recently, PEDOT crystallinity and electron mobility have been improved by treating the PEDOT:PSS aqueous solution with 1-ethyl-3-methylimidazolium- (EMIM-) based ionic liquids (IL) EMIM:X. The amount of such improvement varies drastically with the anion X coupled to EMIM cation in the IL. Herein, using umbrella-sampling molecular dynamics simulations on the aqueous solutions of a minimal model of PEDOT:PSS mixed with various EMIM:X ILs, we show that the solvation of each ion in water plays a major role in the free energies of ion binding and exchange. Anions X efficient for the improvement are weakly stabilized by hydration (i.e., hydrophobic) and prefer binding to hydrophobic PEDOT than to hydrophilic EMIM, favoring the ion exchange. In order to fulfill our design principle, a quantitative criterion based on hydration free energy is proposed to select efficient hydrophobic anions X.

Conductivity enhancement of PEDOT:PSS via the morphological change of PEDOT-rich domains has been achieved by introducing a 1-ethyl-3-methylimidazolium (EMIM)-based ionic liquid (IL) into its aqueous solution, and the degree of such change varies drastically with the anion coupled to the EMIM cation constituting the IL. We carry out a series of molecular dynamics simulations on various simple model systems for the extremely complex mixtures of PEDOT:PSS and EMIM:X IL in water, varying the anion X, the IL concentration, the oligomer model of PEDOT:PSS, and the size of the model systems. The common characteristic found in all simulations is that although planar hydrophobic anions X are the most efficient for ion exchange between PEDOT:PSS and EMIM:X, they tend to bring together planar EMIM cations to PEDOT-rich domains, disrupting PEDOT π-stacks with PEDOT–X–EMIM intercalating layers. Nonplanar hydrophobic anions, which leave most of EMIM cations in water, are efficient for both ion exchange and the formation of extended PEDOT π-stacks, as observed in experiments. Based on such findings, we propose a design principle for new cations replacing EMIM; nonplanar hydrophilic cations combined with hydrophobic anions should improve IL efficiency for PEDOT:PSS treatment.