After doing several miscibility essays with eight ionic liquids (ILs) and four base oils, the ILs tri(butyl)ethylphosphonium diethylphosphate [P4,4,4,2][C2C2PO4] and trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate [P6,6,6,14][(C2F5)3PF3] were selected to be studied as lubricant additives. The neat IL [P4,4,4,2][C2C2PO4], the base oils, and several blends were characterized in terms of density, viscosity, and thermal stability. The tribological performance of the miscible base oil/IL blends (1 wt %) and the neat [P4,4,4,2][C2C2PO4] were evaluated for the lubrication of an AISI 420 steel-100Cr6 steel contact pair. The friction coefficients and wear volumes obtained are also compared with those corresponding to the pure base oils and their mixtures with conventional additive zinc dialkyldithiophosphate (ZDDP). As neat lubricants, [P4,4,4,2][C2C2PO4] showed the best antifriction ability, whereas in terms of wear, better results were obtained with [P6,6,6,14][(C2F5)3PF3]. However, higher improvements in both friction and wear were found for blends containing [P4,4,4,2][C2C2PO4]. XPS analyses of the worn surfaces lubricated with these mixtures indicated the presence of phosphorus in the tribofilm formed on the wear track. However, this compound was slightly detected on tribosamples lubricated with blends containing [P6,6,6,14][(C2F5)3PF3].

The molecular surface structure of four imidazolium based ionic liquids was studied with two surface sensitive techniques. Angle resolved neutral impact collision ion scattering spectroscopy (ARNICISS) allows us to determine elemental concentration depth profiles and to obtain information about the topography of the surface. Angle resolved X-ray photoelectron spectroscopy (ARXPS) can be used to study the chemical composition of the surface. The room temperature ionic liquids (RTILs) 1-ethyl-3-methylimidazolium [EMIM], 1-butyl-3-methylimidazolium [BMIM], 1-hexyl-3-methylimidazolium [HMIM], and 3-methyl-1-octylimidazolium [OMIM] bis(trifluoromethylsulfonyl)imide [Tf(2)N] were investigated at 293 K. No evidence of surface active impurities was observed. The majority of previous studies about these RTILs with ARXPS or other surface sensitive techniques dealt only with single examples of these substances or with different combination of the anion and cation. In this present study a homologous series of the four RTILs mentioned above was investigated. This means that only the number of carbon atoms in the aliphatic chain of the cation is varied. Due to this procedure it is possible to study the influence of the chain length, which is a part of the imidazolic ring, on the composition of the surface and the surface near region. In this paper we demonstrate the potential of ARNICISS as a surface sensitive technique to study the surface structure of the RTILs. Furthermore, we combine our NICISS data with ARXPS data, to get a better comprehension of the influence of the aliphatic chain length. After the presentation of the results we develop a model of the surface structure of different RTILs. We have discovered two different surface structures that depend on the number of carbon atoms inside the aliphatic chain.

Scanning transmission X-ray microscopy (STXM) has been used to probe the electronic structure of individual multiwall carbon nanotubes by chemical mapping at the nanoscale. Carbon 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of individual structures are shown to be able to differentiate carbon nanotubes from onionlike carbon nanoparticles and to differentiate nanotubes synthesized by different growth methods. Imaging of the very same region by both STXM and transmission electron microscopy is shown to be a very useful and complementary approach.

BackgroundMeasures of the expected genetic variability among full-sibs are of practical relevance, such as in the context of mating decisions. An important application field in animal and plant breeding is the selection and allocation of mates when large or small amounts of genetic variability among offspring are desired, depending on user-specific goals. Estimates of the Mendelian sampling variance can be obtained by simulating gametes from parents with known diplotypes. Knowledge of recombination rates and additive marker effects is also required. In this study, we aimed at developing an exact method that can account for both additive and dominance effects.ResultsWe derived parent-specific covariance matrices that exactly quantify the within-family (co-)variability of additive and dominance marker effects. These matrices incorporate prior knowledge of the parental diplotypes and recombination rates. When combined with additive marker effects, they allow the exact derivation of the Mendelian sampling (co-)variances of (estimated) breeding values for several traits, as well for the aggregate genotype. A comparative analysis demonstrated good average agreement between the exact values and the simulation results for a practical dataset (74,353 German Holstein cattle).ConclusionsThe newly derived method is suitable for calculating the exact amount of intra-family variation of the estimated breeding values and genetic values (comprising additive and dominance effects).

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