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901.
The effects of optically active compounds on amphiphilic nematics are reported. The following systems have been studied : (1) caesium decylsulphate, decanol, water plus tartaric acid ; (2) ammonium decylsulphate, ammonium sulphate, decanol, water plus brucine sulphate ; and (3) decylammonium chloride, water plus cholesterol. Phase transitions to cholesteric states are induced by the optically active compounds in all systems. Brucine sulphate has the highest twisting power ; tartaric acid the lowest. The results are analysed on the basis of intermolecular interactions and an explanation is proposed for the observed differences in twisting power. 相似文献
902.
903.
Alexandra Wittmar Matthias Wittmar Alfred Ulrich Hinka Caparrotti Michael Veith 《Journal of Sol-Gel Science and Technology》2012,61(3):600-612
The protective capabilities of sol–gel coatings are determined by their physical barrier properties. For an effective protection,
a homogenous crack-free material is required, which prevents from attacks of corrosive species. When the coating is damaged,
active corrosion protection is usually achieved by the use of inhibitors. Among the different inhibitors rare earth ions and
especially cerium have shown effective inhibiting properties. Due to the complexity of the corrosion processes, a combination
of inhibitors is expected to be superior to a monocomponent inhibiting. The aim of this study was to prove which other ions,
used in combination with cerium, can improve the corrosion protection abilities of hybrid silica based inorganic–organic sol–gel
coatings applied on aluminium alloy 2024 substrates. Mixtures of cerium nitrate with two other potential inhibitor substances
were incorporated into a sol–gel matrix and their behaviour in neutral salt spray test and during EIS measurements was investigated.
The Ce–P–Pr inhibitor combination (Ce3+, PO4
3−, Pr3+) has shown the best long-term corrosion protection properties at low doping levels. 相似文献
904.
905.
Alfred Geroldinger David J. Grynkiewicz Wolfgang A. Schmid 《Acta Mathematica Hungarica》2011,131(4):323-345
For a finite abelian group G and a positive integer d, let s
dℕ(G) denote the smallest integer ℓ∈ℕ0 such that every sequence S over G of length |S|≧ℓ has a nonempty zero-sum subsequence T of length |T|≡0 mod d. We determine s
dℕ(G) for all d≧1 when G has rank at most two and, under mild conditions on d, also obtain precise values in the case of p-groups. In the same spirit, we obtain new upper bounds for the Erdős–Ginzburg–Ziv constant provided that, for the p-subgroups G
p
of G, the Davenport constant D(G
p
) is bounded above by 2exp (G
p
)−1. This generalizes former results for groups of rank two. 相似文献
906.
907.
908.
909.
910.
Thue Pascal S. dos Reis Glaydson S. Lima Eder C. Sieliechi Joseph M. Dotto G. L. Wamba Alfred G. N. Dias Silvio L. P. Pavan Flavio A. 《Research on Chemical Intermediates》2017,43(2):1063-1087
Research on Chemical Intermediates - Activated carbon (AC) was prepared from sapelli wood sawdust using a microwave heating process. The biomass was mixed with inorganic components... 相似文献