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Modifying Fragility and Collective Motion in Polymer Melts with Nanoparticles
We investigate the impact of nanoparticles (NP) on the fragility and
cooperative string-like motion in a model glass-forming polymer melt by
molecular dynamics simulation. The NP cause significant changes to both the
fragility and the average length of string-like motion, where the effect
depends on the NP-polymer interaction and the NP concentration. We interpret
these changes via the Adam-Gibbs (AG) theory, assuming the strings can be
identified with the "cooperatively rearranging regions" of AG. Our findings
indicate fragility is primarily a measure of the temperature dependence of the
cooperativity of molecular motion.Comment: To appear in Physical Review Letter
Measurements of ozone in the Antarctic region during August and September of 1987
Mixing ratios are presented for ozone in the austral polar atmosphere during Aug. and Sept. of 1987. Since the mid-1970's, there has been a continuing decrease in the total column abundance of ozone over Antarctica during the late winter and early spring. This reduction now amounts to about one-half of the historical October mean. The results presented are derived from an ultraviolet ozone photometer. The ER-2 aircraft carrying 14 instruments participated in a major effort to penetrate the region of depletion. Data were gathered between altitudes of 53 deg and 72 deg S at pressure altitudes up to 21 km in a series of 12 flights. Additional data were obtained between latitudes of 37 deg N and 53 deg S on the 3 flight legs required to reach Punta Arenas from Moffett Field, CA, and on the same return legs to Moffett Field. The observed ozone mixing ratios indicate the effects of chemistry as well as the effects of the stratospheric polar vortex. Examples of the distributions of ozone mixing ratios as a function of altitude, latitude, or a time and the relationships to temperature and other trace gases are presented
Article 3: Commercial Paper
Montana Law and the Uniform Commercial Code: Article 3: Commercial Pape
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