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Filled skutterudites are high-performance thermoelectric materials and we show how their phonon conductivity is greatly influenced by the topology of the filler species. We predict (ab initio) the phase diagram of Ba(x)Co4Sb12 and find several stable configurations of Ba ordering over the intrinsic voids. The phonon conductivity predicted using molecular dynamics shows a minimum in the two-phase mixture regime, dominated by significantly reduced long-range acoustic phonon transport. 相似文献
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66.
Combined vibrational,conformational and electron diffraction studies of 2,2,6-trimethylcyclohexanone
The molecular structure of 2,2,6-trimethylcyclohexanone was studied by electron diffraction in the vapor phase combined with auxiliary vibrational and conformational calculations, ra = 1.535 ± 0.004 and ra = 1.108 ± 0.015 were found for the average C-H and C-C bonds, respectively, from data taken at both the Oslo and Arkansas electron diffraction units. Five local conformational energy minima (2 rigid (chair) and 3 flexible (boat) ones) were found for the molecule. Data analysis revealed that, at 70° C, the vapors of the compound contained essentially one conformer in a chair form with two of the three methyl-substituents in equatorial positions. Molecular mechanics results based on different force fields taken from the literature were compared, and found to be in fair agreement. 相似文献
67.
Tahereh PoursaberiMorteza Hosseini Massoud TaghizadehHooshang Pirelahi Mojtaba ShamsipurMohammad Reza Ganjali 《Microchemical Journal》2002,72(1):77-83
A highly selective electrode for iodide ion based on a thiopyrilium derivative as an excellent ionophore is described. At pH 5.5-8.0, the electrode responds to iodide ion in a linear range from 1.0×10−1 to 8.0×10−7 M with a slope of 60.2 mV per decade, and a detection limit of 2.0×10−7 M. Selectivity coefficients determined with the match potential method (MPM) indicate that the interference from inorganic and organic anions is very small. The proposed sensor shows a fast response time of approximately 15 s. It was applied as an indicator electrode in titration of iodide with Ag+. 相似文献
68.
Let φ:(R,m)→S be a flat ring homomorphism such that mS≠S. Assume that M is a finitely generated S-module with dimR(M)=d. If the set of support of M has a special property, then it is shown that if and only if for each prime ideal satisfying , we have . This gives a generalization of the Lichtenbaum-Hartshorne vanishing theorem for modules which are finite over a ring homomorphism. Furthermore, we provide two extensions of Grothendieck’s non-vanishing theorem. Applications to connectedness properties of the support are given. 相似文献
69.
[Cr(en)2CO3]I (I), ICoO3N4C5H16, crystallizes from water at 21°C in space groupP21/c (no. 14), with lattice constantsa=7.298(4),b=8.622(8),c=17.577(6)Å,=91.29(4)°;V=1105.59 Å3 andd(calc; MW=359.11, Z=4)=2.157 g cm–3. A total of 2825 data points were collected over the range of 4°250°; of these, 1855 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=37.657 cm–1) and the transmission coefficients ranged from 0.4850 to 0.9991. The finalR(F) andR
w(F) residuals were, respectively 0.134 and 0.113. The cations exist in the lattice as the enantiomeric pair () and (). NH4{[cis--Co(trien)CO3]2}(PF6)3 (II), Co2P3F18O6N9C14H40, crystallizes from water at 21 °C in space groupP21/c (no. 14), with lattice constantsa=10.397(2),b=20.292(3),c= 27.082(4) Å,=100.30(3)°;V=3545.70 Å3 andd(calc; MW=983.29, Z=4)=1.842 g cm–3. A total of 3724 data were collected over the range of 4°250°; of these, 2653 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=12.031 cm–1) and the transmission coefficients ranged from 0.8326 to 0.99985. The finalR(F) andR
w
(F) residuals were, respectively 0.104 and 0.124. The cations exist in the asymmetric unit as() and()[cis--Co(trien)CO3]+ pairs. The three independent PF6
– anions exhibit the usual high thermal motion typical of these species and the NH4
+ cation is either disordered or exhibits high thermal motion also (its H atoms could not be found in difference maps). 相似文献
70.
Richard S. Glass Massoud Hojjatie Amorn Petsom George S. Wilson Manfred Göbl Sabine Mahling 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):143-168
Abstract Oxidation of thioethers is greatly facilitated by neighboring group participation by carboxylate, alcohol, and thioether moieties. 相似文献