Anosov automorphisms on compact nilmanifolds associated with graphs

We associate with each graph a -step simply connected nilpotent Lie group and a lattice in . We determine the group of Lie automorphisms of and apply the result to describe a necessary and sufficient condition, in terms of the graph, for the compact nilmanifold to admit an Anosov automorphism. Using the criterion we obtain new examples of compact nilmanifolds admitting Anosov automorphisms, and conclude that for every there exist a -dimensional -step simply connected nilpotent Lie group which is indecomposable (not a direct product of lower dimensional nilpotent Lie groups), and a lattice in such that admits an Anosov automorphism; we give also a lower bound on the number of mutually nonisomorphic Lie groups of a given dimension, satisfying the condition. Necessary and sufficient conditions are also described for a compact nilmanifold as above to admit ergodic automorphisms.

     

Cyanoethylation of methyl and ethyl ethers of dimethylphenols

The C-cyanoethylation of the methyl and ethyl ethers of dimethylphenols has been carried out with acrylonitrile in the presence of anhydrous AlCl₃ to furnish propionitrile derivatives. The latter on hydrolysis to the corresponding propionic acids followed by cyclization with PPA afforded the appropriate indanones, whose structures have been established on the basis of spectral data and by the formation of 2, 4-DNP derivatives.     

Phytochemical and antioxidant properties of some Cassia species

In this study, the antioxidant activity of aqueous and ethanol extracts of four plants from the genus Cassia were evaluated by various antioxidant assays, including ferric reducing antioxidant power (FRAP), DPPH free radical scavenging, metal chelating activity, phosphomolybdenum reducing power, hydrogen peroxide radical scavenging, hydroxyl radical scavenging, deoxyribose degradation and β-carotene bleaching assay. The various antioxidant activities were compared to standard antioxidant such as ascorbic acid. All the extracts showed antioxidant activity in the tested methods. Among the four species, Cassia auriculata has been found to possess highest activity in most of the tested models. In addition to the antioxidant activity, the total phenolics and flavonoids were measured in the extracts. The ethanolic extract exhibited highest phenolics and flavonoid contents and had also shown potent antioxidant activity in comparison to the aqueous extracts. The possible antioxidant mechanism of the ethanol extract can be due to its hydrogen or electron donating and direct free radical scavenging properties. Hence, the ethanol extract represents a source of potential antioxidants that could be used in pharmaceutical industries.     

Production, Purification, and Characterization of a β-Glucosidase of Penicillium funiculosum NCL1

Penicillium funiculosum NCL1, a filamentous fungus, produced significantly higher levels of ??-glucosidase. The effect of initial pH, incubation temperature, and different carbon sources on extracellular ??-glucosidase production was studied in submerged fermentation. At 30?°C with initial pH 5.0, enzyme production was increased by 48-fold upon induction with paper mill waste, as compared to commercial cellulose powder. In zymogram analysis, four isoforms of ??-glucosidases were observed with wheat bran whereas a minimum of one isoform was observed with other carbon sources. A major ??-glucosidase (Bgl3A) with the apparent molecular weight of ~120?kDa, induced by paper mill waste, was purified 19-fold to homogeneity, with a specific activity of 1,796 U/mg. Bgl3A was a monomeric glycoprotein with 29% of neutral carbohydrate content. It showed optimum activity at pH 4.0 and 5.0, optimum temperature at 60?°C, and exhibited a half-life of 1?h at 60?°C. K _m of Bgl3A was found to be 0.057?mM with p-nitrophenyl ??-d-glucoside and V _max was 1,920 U/mg. The purified enzyme exhibited glucose tolerance with a K _i of 1.5?mM. Bgl3A readily hydrolyzed glucosides with ??-linkage. Bgl3A activity was enhanced (156%) by Zn²⁺ and was not affected by other metal cations and reagents. The supplementation of Bgl3A (5 U/mg) with Trichoderma reesei cellulase complex (5 FPU/mg) resulted in about 70% of enhanced glucose production, which emphasizes the industrial importance of Bgl3A.     

Regioselective N‐alkylation for the synthesis of novel aminotriazolophanes

Regioselective synthesis of macrocycles, incorporating 3‐oxo‐4‐amino‐1,2,4‐triazole derivatives, has been achieved by reactions involving N‐alkylation, utilizing appropriate 1, ω ‐dihaloalkanes in the presence of metal hydroxide. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:329–336, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20211     

B(C6F5)3-Enabled Synthesis of a Cyclic cis-Arsaphosphene

The synthesis and characterization of an (arsino)phosphaketene, As(PCO){[N(Dipp)](CH₂)}₂ (Dipp=2,6-diisopropylphenyl) is reported along with its subsequent reactivity with B(C₆F₅)₃. When reacted in a stoichiometric ratio, B(C₆F₅)₃ drove the insertion of the P=C bond of the phosphaketene into one of the As−N bonds of the arsino functionality, affording an acid-stabilized, seven-membered, cyclic arsaphosphene. In contrast, when catalytic amounts of B(C₆F₅)₃ were employed, dimeric species, which formed through a formal [2+2] cycloaddition of the cyclic arsaphosphene, were generated. The cyclic arsaphosphene product represents the first example of such a compound in which the two substituents are arranged in a cis-configuration.     

Evaluation of ethoxynonafluorobutane as a safe and environmentally friendly solvent for chiral normal-phase LC-atmospheric pressure chemical ionization/electrospray ionization-mass spectrometry

Coupling normal-phase LC separation methods to atmospheric pressure ionization (API)-mass spectrometry (MS) for detection can be problematic because of the possible detonation hazard and because nonpolar solvents do not support ionization of the analyte. Unlike achiral separations, enantiomeric separations can be very sensitive to small changes in the separation environment. Thus, completely substituting the main mobile phase component of a normal-phase LC solvent for an environmentally friendly, nonflammable fluorocarbon-ether as a safe and effective solvent must be thoroughly evaluated before it can be recommended for enantioselective separations with API-MS detection. Ethoxynonafluorobutane (ENFB) was used as a normal-phase solvent for the enantioselective separation of 15 compounds on two macrocyclic glycopeptide chiral stationary phases (CSPs) and a new polymeric chiral stationary phase. The chromatographic figures of merit were compared between results obtained with the ENFB mobile phases and traditional heptane-based mobile phases. In addition, the limits of detection (LOD) using the API-MS compatible ENFB were examined, as well as flow rate sensitivities and compatibilities with common polar organic modifier. ENFB is a safe and effective solvent for enantioselective normal-phase/API-MS analyses.