In the synthesis of binuclear organobismuth complexes (1-6) through treatment of organobismuth chlorides with NaOH or Na2S-9H20, the two 5,6,7,12-tetrahydrodibenz c,fl- 1,5azabismocine frameworks are ...cross-linked by either a sulfur or an oxygen atom. The complexes (1-6) show high catalytic efficiency in the synthesis of cyclic carbonates from 2- (chloromethyl)oxirane and C02. Compared with their precursor chlorides (7-9), methoxide 10 and methanethioate 11 which are mononuclear organobismuth complexes, the binuclear or- ganobismuth complexes show higher cooperative catalytic effect. However, the complexes with an oxygen bridge (1-3) are not stable in air and lose their catalytic efficiency because of hydrolysis or C02 adsorption (forming organobismuth carbo- nates in the latter case). Nonetheless, the binuclear organobis- muth complexes (4-6) with a sulfur bridge are highly stable in air and can be applied in the synthesis of cyclic carbonates (with the co-presence of Bu4NI) across various kinds of epox- ides, thus exhibiting satisfactory efficiency and selectivity. PUBLICATION ABSTRACT
Gaussian mixture models (GMM) have become one of the standard acoustic approaches for language identification. Furthermore, the GMM-SVM is proven to work well by introducing the discriminative method ...into the GMM-based acoustic systems. In these systems, the intersession variability within language has become an important adverse factor that degrades the system performance. To tackle this problem, we propose a subspace analysis method, termed as Intra-language Difference Subspace Estimatio (IDSE), under the GMM-SVM framework. In IDSE method, the difference vector is modeled with three components: Extra-language difference, Intra-language difference and noise difference. Then the Intra-language and noise difference are effectively estimated and eliminated from the difference vector. The experiments on NIST 07 evaluation tasks show effectiveness of the proposed method.
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