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A.A.Leslie Gunatilaka Subramaniam Sotheeswaran H.T.Badra Sriyani Eric S. Waight 《Tetrahedron letters》1982,23(29):2987-2990
Hermonionic acid and its decarboxylated product have been isolated from . 13C NMR spectral and chemical evidence indicate that hermonionic acid is 2-0-[2-(3-methylbut-2-enyl)-3-methoxy- 4-hydroxy-5-(3,7-dimethylocta-2,6-dienyl]-4-methoxy-5-(3-methylbut-2-enyl-6-hydroxybenzoic acid. The previously assigned dienone structure for this acid is incorrect. 相似文献
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Young Derek S. Chen Xi Hewage Dilrukshi C. Nilo-Poyanco Ricardo 《Advances in Data Analysis and Classification》2019,13(4):1053-1082
Advances in Data Analysis and Classification - Finite mixtures of (multivariate) Gaussian distributions have broad utility, including their usage for model-based clustering. There is increasing... 相似文献
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Vieira HS Takahashi JA Gunatilaka AA Boaventura MA 《Magnetic resonance in chemistry : MRC》2006,44(2):146-150
A highly rearranged novel dilactone was the single product isolated from Baeyer-Villiger oxidation of a norketone prepared from grandiflorenic acid, a natural kaurane diterpene. The complete 1H and 13C NMR assignment is presented for this novel compound that showed discrete in vitro antibacterial activity. 相似文献
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The two D:A-friedo-oleanane triterpenes kokzeylanol and kokzeylanonol isolated from the inner bark of Kokoona zeylanica have been characterized as 6β,27-dihydroxy-D:A -friedo-olean-3-one and 6β,27-dihydroxy-D:A-friedo-olean-3,21-dione, respectively, by the deoxygenation of their 27-acetoxy derivatives using lithium-ethylenediamine reduction coupled with spectroscopic and irradiation methods. Kokzeylanonol represents the first tetra-oxygenated D:A-friedo-oleanane triterpene obtained from a nautral source. Significance of some of these D:A-friedo-oleananes in the biosynthesis of quinonoid triterpenes in Celastraceae is discussed. 相似文献
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Jinasena W. Hewage 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(6):1-11
Molecular dynamics simulation (MD) with Sutton-Chen potential for palladium-palladium, nickel-nickel and palladium-nickel interactions has been used to generate the minimum energy structures and to study the thermodynamic and dynamic properties of mixed transition metal cluster motifs of Ni n Pd(13?n) for n ≤ 13. Thirteen particle icosahedral clusters of neat palladium and nickel atoms were first reproduced accordingly with the results in literature. Then in the palladium icosahedra, each palladium atom has been successively replaced by nickel atom. Calculation is repeated for both palladium-centered and nickel-centered clusters. It is found that the nickel-centered clusters are more stable than the palladium-centered clusters and cohesive energy increases along the palladium end to nickel end. Phase transition of each cluster from one end-species to the other end-species is studied by means of caloric curve, root mean square bond fluctuation and heat capacity. Trend in variation of melting temperature is opposite to the energy trend. Palladium-centered cluster shows a premelting at low temperature due to the solid-solid structural transition. Species-centric order parameters developed by Hewage and Amar is used to understand the dynamic behavior in the solid-solid transition of palladium-centered cluster to more stable nickel-centered cluster (premelting). This species-centric order parameter calculation further confirmed the stability of nickel-centered species over those of palladium-centered species and solid-solid structural transition at low temperature. 相似文献
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J. W. Hewage F. G. Amar M.-F. de Feraudy G. Torchet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):249-252
Using realistic pair potentials, we investigate the
structures of mixed clusters of argon and nitrogen in order to
interpret the experimental electron diffraction patterns
reported by the Torchet group. Simulations of small clusters
indicate that argon tends to segregate at the center of the
clusters. For larger clusters, in the range of 50 to 200
molecules, MC methods have been used to simulate structures that
are likely to be generated in the molecular beam. By comparing
predicted electron diffraction patterns with those recorded in
the experiments, our models allow us to estimate the average
size and composition of the mixed clusters for a given set of
experimental conditions (nozzle stagnation pressure and Ar
partial pressure). 相似文献
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A. A. Leslie Gunatilaka N. P. Dhammika Nanayakkara M. Uvais S. Sultanbawa Mohamed I. M. Wazeer 《Magnetic resonance in chemistry : MRC》1982,18(1):53-54
13C NMR spectra of 27-hydroxyfriedelane, kokoonol (27-hydroxyfriedelan-3-one) and kokoononol (27-hydroxyfriedelan-3,21-dione) have been recorded and signals assigned using the off-resonance decoupling, inversion recovery and lanthanide induced shift techniques. 相似文献
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Marc Bria Alan Cooper Shanika Gunatilaka Hewage Margaret Nutley 《Tetrahedron letters》2007,48(48):8430-8433
This Letter, describes the complexation of α-, β- and γ-cyclodextrins (1-3) with TTF derivative 4 in water. In particular, we show using 1H, 13C NMR, UV-vis spectroscopy and isothermal titration calorimetry that β-cyclodextrin 2 forms an effective complex with 4. Complex 2·4 can be conveniently disassembled upon the addition of 1-adamantanol. 相似文献