Homocysteine and B-group vitamins in renal transplant patients

Increased plasma homocysteine is an independent risk factor for cardiovascular disease. We have investigated homocysteine and B-group vitamin levels in renal transplant patients. Fasting blood was collected from 55 renal transplant recipients with good renal function and 32 age/sex matched control subjects. Total homocysteine was increased in transplant recipients in comparison to controls (10.9+/-1.5 vs. 6.7+/-1.3 micromol/l, P < 0.001). There was no difference in homocysteine between patients receiving cyclosporin (n = 39, homocysteine 11.0+/-1.5 micromol/l) and patients receiving prednisolone + azathioprine (n = 16, 10.8+/-1.6 micromol/l, mean+/-S.D.), although there was a significant correlation between homocysteine and serum cyclosporin concentration in the sub-group of patients receiving that immunosuppressive regimen (r = 0.42, P < 0.05). Levels of B-group vitamins were similar in patients and controls. Plasma homocysteine is increased in renal transplant recipients even in the presence of minor degrees of renal impairment and normal levels of B-group vitamins.

Boron in copper: A perfect misfit in the bulk and cohesion enhancer at a grain boundary

Using first principles electronic structure methods, we calculate the effects of boron impurities in bulk copper and at surfaces and grain boundaries. We find that boron segregation to the Sigma5(310)[001] grain boundary should strengthen the boundary up to 1.5 ML coverage (15.24 at./nm2). The maximal effect is observed at 0.5 ML and corresponds to boron atoms filling exclusively grain boundary interstices. In copper bulk, B causes significant distortion both in interstitial and regular lattice sites, for which boron atoms are either too big or too small. The distortion is compensated to a large extent when the interstitial and substitutional boron combine together to form a strongly bound dumbbell. Our prediction is that bound boron impurities should appear in a sizable proportion if not dominate in most experimental conditions. A large discrepancy between calculated heats of solution and experimental terminal solubility of B in Cu is found, indicating either a significant failure of the density functional approach or, more likely, strongly overestimated solubility limits in the existing B-Cu phase diagram.

Extension of the Ye and Shreeve group contribution method for density estimation of ionic liquids in a wide range of temperatures and pressures

An extension of the Ye and Shreeve group contribution method [C. Ye, J.M. Shreeve, J. Phys. Chem. A 111 (2007) 1456–1461] for the estimation of densities of ionic liquids (ILs) is here proposed. The new version here presented allows the estimation of densities of ionic liquids in wide ranges of temperature and pressure using the previously proposed parameter table. Coefficients of new density correlation proposed were estimated using experimental densities of nine imidazolium-based ionic liquids. The new density correlation was tested against experimental densities available in literature for ionic liquids based on imidazolium, pyridinium, pyrrolidinium and phosphonium cations. Predicted densities are in good agreement with experimental literature data in a wide range of temperatures (273.15–393.15 K) and pressures (0.10–100 MPa). For imidazolium-based ILs, the mean percent deviation (MPD) is 0.45% and 1.49% for phosphonium-based ILs. A low MPD ranging from 0.41% to 1.57% was also observed for pyridinium and pyrrolidinium-based ILs.

A group contribution method for viscosity estimation of ionic liquids

Based on experimental viscosity data collected from the literature and using density data obtained from a predictive method previously proposed by the authors, a group contribution method is proposed to estimate viscosity of imidazolium-, pyridinium-, and pyrrolidinium-based ILs containing hexafluorophosphate (PF6), tetrafluoroborate (BF4), bis(trifluoromethanesulfonyl) amide (Tf2N), chloride (Cl), acetate (CH3COO), methyl sulfate (MeSO4), ethyl sulfate (EtSO4), and trifluoromethanesulfonate (CF3SO3) anions, covering wide ranges of temperature, 293–393 K and viscosity, 4–21,000 cP. It is shown that a good agreement with literature data is obtained. For circa 500 data points of 29 ILs studied, a mean percent deviation (MPD) of 7.7% with a maximum deviation smaller than 28% was observed. 71.1% of the estimated viscosities present deviations smaller than 10% of the experimental values while only 6.4% have deviations larger than 20%. The group contribution method here developed can thus be used to evaluate the viscosity of new ionic liquids in wide ranges of temperatures at atmospheric pressure and, as data for new groups of cations and anions became available, can be extended to a larger range of ionic liquids.