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Ivo Düntsch 《Algebra Universalis》1987,24(3):197-203
We characterize the injective and projective regular double Stone algebras, and describe those regular double Stone algebras which are also projective in the category of double Stone algebras.Presented by Bjarni Jónsson. 相似文献
86.
Ivo Babu
ka 《Finite Elements in Analysis and Design》1987,3(4):341-354
This paper addresses the finite element method with a posteriori error estimation for elements of degree p = 1 and p = 2. It gives the formulae for the error indicators and error estimators. Basic mathematical characterizations of the estimators are given and it is shown that the estimators for p = 1 and p = 2 have different structures. Numerical examples show the effectivity of the approach and the high quality of the estimator. 相似文献
87.
Ivo Deiglmayr 《Fresenius' Journal of Analytical Chemistry》1909,48(2):122-123
Ohne Zusammenfassung 相似文献
88.
89.
Ivo A. Hümmelgen 《Journal of Solid State Electrochemistry》2007,11(11):1463-1463
90.
Patrick J. M. Stals Jeffrey C. Everts Robin de Bruijn Ivo A. W. Filot Maarten M. J. Smulders Rafael Martín‐Rapún Dr. Evgeny A. Pidko Dr. Tom F. A. de Greef Dr. Anja R. A. Palmans Dr. E. W. Meijer Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(3):810-821
N‐Centred benzene‐1,3,5‐tricarboxamides (N‐BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid‐state behaviour and self‐assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X‐ray diffraction revealed that the chiral N‐BTA derivatives with branched 3,7‐dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Colho. In contrast, N‐BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable‐temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N‐BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N‐BTAs revealed a cooperative self‐assembly behaviour of the N‐BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants‐and‐soldiers as well as the majority‐rules principles were operative in stacks of N‐BTAs. In fact, the self‐assembly of N‐BTAs resembles closely that of their carbonyl (C?O)‐centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self‐assembly of N‐ and C?O‐BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N‐BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the Ph? NH bond compared to the Ph? CO bond and the diminished magnitude of dipole–dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N‐BTAs and C?O BTAs. 相似文献