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We measured the electrolytic conductivities of the electrolytes of LiPF6 in ethylene carbonate-ethyl methyl carbonate at different salt contents, solvent compositions, and temperatures in the ranges of their practical values. To these data, we fitted a fourth degree trivariate polynomial and obtained a close fit. We then plotted this function as surface and contour plots in the coordinates of salt content and solvent composition for a series of temperatures. These plots showed the change of conductivity with the simultaneous changes of salt content and solvent composition and the influence of temperature on this change, thus mapping the locations for the optimal combinations of salt content and solvent composition for maximum conductivity of the electrolytes at desired temperatures. Here we also discuss and interpret qualitatively the trends found in the change of conductivity with salt content, solvent composition, and temperature, based on the dependency on the same variables of these three factors: the number of dissociated ions in the electrolyte, the dielectric constant of the solvent, and the viscosity of the electrolyte. © 2001 The Electrochemical Society. All rights reserved.

We studied diabetes mellitus and glucose and insulin levels in Air Force veterans exposed to Agent Orange and its contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), during the Vietnam War. The index subjects of the Air Force's ongoing 20-year prospective epidemiologic study are veterans of Operation Ranch Hand (N = 989), the unit responsible for aerial herbicide spraying in Vietnam from 1962 to 1971. Other Air Force veterans who served in Southeast Asia during the same period but were not involved with spraying herbicides serve as Comparisons (N = 1,276). The median serum dioxin level in the Ranch Hand group was 12.2 parts per trillion (ppt) (range = 0-617.8 ppt), and the median dioxin level in the Comparison group was 4.0 ppt (range = 0-10 ppt). We found that glucose abnormalities [relative risk = 1.4; 95% confidence limits (CL) = 1.1, 1.8], diabetes prevalence (relative risk = 1.5; 95% CL = 1.2, 2.0), and the use of oral medications to control diabetes (relative risk = 2.3; 95% CL = 1.3, 3.9) increased, whereas time-to-diabetes-onset decreased with dioxin exposure. Serum insulin abnormalities (relative risk = 3.4; 95% CL = 1.9, 6.1) increased with dioxin exposure in nondiabetics. These results indicate an adverse relation between dioxin exposure and diabetes mellitus, glucose metabolism, and insulin production.