1,051 research outputs found
Highly Active Water-Soluble Olefin Metathesis Catalyst
A novel water-soluble ruthenium olefin metathesis catalyst supported by a poly(ethylene glycol) conjugated saturated 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene ligand is reported. The catalyst displays improved activity in ring-opening metathesis polymerization, ring-closing metathesis, and cross-metathesis reactions in aqueous media
Decomposition of a Key Intermediate in Ruthenium-Catalyzed Olefin Metathesis Reactions
Dinuclear ruthenium complex, with a bridging carbide and a hydride ligand, and methyltricyclohexylphosphonium chloride result from thermal decomposition of olefin metathesis catalyst, (ImesH_2)(PCy)_3)(Cl)_2Ru CH_2. Involvement of dissociated phosphine in the decomposition is proposed. The dinuclear complex has catalytic olefin isomerization activity, which can be responsible for competing isomerization processes in certain olefin metathesis reactions
Prevention of Undesirable Isomerization during Olefin Metathesis
1,4-Benzoquinones have been found to prevent olefin isomerization of a number of allylic ethers and long-chain aliphatic alkenes during ruthenium-catalyzed olefin metathesis reactions. Electron-deficient benzoquinones are the most effective additives for the prevention of olefin migration. This mild, inexpensive, and effective method to block olefin isomerization increases the synthetic utility of olefin metathesis via improvement of overall product yield and purity
Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium
A metastable phase of body-centered-tetragonal ruthenium (bct Ru) is identified to exhibit a large perpendicular magnetocrystalline anisotropy (PMCA), whose energy E-MCA is as large as 150 mu cV/atom, which is two orders of magnitude greater than those of 3d magnetic metals. Further investigation over the range of tetragonal distortion suggests that the appearance of magnetism in the bct Ru is governed by the Jahn-Teller spit e(g) orbitals. Moreover, from band analysis, MCA is mainly determined by an interplay between two e(g) states, d(x)(-y)(2)(2)and d(z)(2) states, as a result of level reversal associated with tetragonal distortion.open1
Characterisation and biofilm screening of the predominant bacteria isolated from whey protein concentrate 80
International audienceAbstractThe source of microbiological contamination of whey protein concentrate (WPC), a quality problem for the dairy industry, has not been thoroughly investigated. The objectives of this study were to identify the bacteria isolated from whey protein concentrate containing 80% protein (WPC 80) and determine their ability to form biofilms as a potential source of contamination in a whey processing line. Six Bacillus species including (percentage of isolates in brackets) Bacillus licheniformis (67%), Bacillus cereus (19%), Bacillus thuringensis (4%), Bacillus subtilis (4%), Bacillus pumilus (4%) and Paenibacillus glucanolyticus (2%) were identified based on BLAST databases in six different WPC80 batches. B. licheniformis was the predominant isolate. B. licheniformis are thermo-tolerant bacteria with the ability to form biofilm. This biofilm is a potential source of microbial contamination of product, resulting in microbial specification limits being exceeded. Spoilage of product may result from the metabolic products, such as enzymes, produced by these biofilms
Warped product approach to universe with non-smooth scale factor
In the framework of Lorentzian warped products, we study the
Friedmann-Robertson-Walker cosmological model to investigate non-smooth
curvatures associated with multiple discontinuities involved in the evolution
of the universe. In particular we analyze non-smooth features of the spatially
flat Friedmann-Robertson-Walker universe by introducing double discontinuities
occurred at the radiation-matter and matter-lambda phase transitions in
astrophysical phenomenology.Comment: 10 page
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