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Phyllocladene has been converted into some 15- and 16-oxo derivatives. The rotary dispersion curves of these indicate that XV is the most likely structure for mirene. 相似文献
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P. Bonville J. A. Hodges F. Hulliger P. Imbert G. Jéhanno J. B. Marimon Da Cunha H. R. Ott 《Hyperfine Interactions》1988,40(1-4):381-384
170Yb Mössbauer measurements show that the heavy electron compound YbAs undergoes a first order paramagnetic-antiferromagnetic transition centered at TN=0.58K. The saturated 4f-shell magnetic moments are reduced by 47% relative to the value predicted by a crystal field model. A study of the line shapes below TN in the presence of an external field shows that the RKKY exchange energy is about 20 times bigger than kB TN. These results show that YbAs presents a magnetic order frustrated by the Kondo effect.supported by CNPq 相似文献
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We measured room-temperature H2O spectra of the 3ν polyad within the wave number range 10 603 cm−1 to 10 852 cm−1 using frequency-stabilized cavity ring-down spectroscopy. More than 70 transitions, divisible into two groups based on their relative intensities (strong and weak) were investigated. For the 23 lines comprising the set of strong transitions, the water vapor sample was prepared as a dilute mixture in a steady flow of N2 carrier gas, and the measurement of the water vapor sample number density was linked to primary methods of humidity generation. For these strong transitions, the measured line intensities were within 1% of previous measurements. The line intensity measurements of the weaker H2O transitions, were made on samples of static pure water vapor, and these results were systematically greater than previous measurements by approximately 20%. 相似文献
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Mercie N. Hodges Matthew J. Elardo Jinyoung Seo Alexander F. Dohoda Prof. Dr. Forrest E. Michael Prof. Dr. Matthew R. Golder 《Angewandte Chemie (International ed. in English)》2023,62(20):e202303115
Accumulation of end-of-life plastics presents ongoing environmental concerns. One strategy to solve this grand challenge is to invent new techniques that modify post-consumer waste and impart new functionality. While promising approaches for the chemical upcycling of commodity polyolefins and polyaromatics exist, analogous approaches to repurpose unsaturated polymers (e.g., polybutadiene) are scarce. In this work, we propose a method to upcycle polybutadiene, one of the most widely used commercial rubbers, via a mild, metal-free allylic amination reaction. The resulting materials have tunable thermal and surface wetting properties as a function of both sulfonamide identity and grafting density. Importantly, this approach maintains the parent alkene microstructure without evidence of olefin reduction, olefin transposition, and/or chain scission. Based on these findings, we anticipate future applications in the remediation of complex elastomers and vulcanized rubbers. 相似文献