Search results for "Reaction"
showing 10 items of 6134 documents
Common genomic structure for the Lepidoptera cadherin-like genes.
2005
A cadherin-like protein present in the midgut epithelial cells of Lepidoptera is associated with insect resistance to Bacillus thuringiensis Cry toxins. We describe for the first time the genes that encode the cadherin-like proteins in Ostrinia nubilalis, Helicoverpa armigera, and Bombyx mori, and analyze their organization. These genes encompass 19.6 kb, 20.0 kb, and 41.8 kb of genomic DNA, respectively, and despite the size heterogeneity, they are all composed of 35 exons that are linked by 34 introns. In contrast to the high variability noted for the sizes of the introns, the sizes of the coding exons were almost completely preserved among the three species, because the intronic sequence…
bilbo, a non-LTR retrotransposon of Drosophila subobscura: a clue to the evolution of LINE-like elements in Drosophila
1997
We used the repetitive character of transposable elements to isolate a non-LTR retrotransposon in Drosophila subobscura. bilbo, as we have called it, has homology to TRIM and LOA elements. Sequence analysis showed a 5' untranslated region (UTR), an open reading frame (ORF) with no RNA-binding domains, a downstream ORF that had structural homology to that of the I factor, and, finally, a 3' UTR which ended in several 5-nt repeats. The results of our phylogenetic and structural analyses shed light on the evolution of Drosophila non-LTR retrotransposons and support the hypothesis that an ancestor of these elements was structurally complex.
Effect of 5% body weight forward pulling on dynamics of treadmill running
2003
Forward pulled running on a treadmill is known to increase mechanical and decrease metabolic constrains relative to normal running. This experimental situation was used to investigate the variations of the mechanical parameters induced by the pulling. Ten subjects ran during 3 min at individually predetermined constant speeds of 16.4 ± 1.4 km · h-1 on a treadmill while being forward pulled by a load equal to 5% of their body weight. Ground reaction forces were recorded during the last 30 s of the run. Kinematic parameters of the stride as well as impulses and mechanical work were then calculated. Stride frequency did not change, while horizontal impulses were highly modified (+38% and -28%,…
Fluorescenzserologischer Nachweis eines in Syphilitikerseren vorkommenden Antik�rpers gegen ein hitzestabiles Antigen der Reiter-Treponemen
1967
An insgesamt 88 Syphilitikerseren wurde der FTA-Test mit erhitzten Reiter-Treponemen durchgefuhrt. 71 mal reagierte die Serumverdunnung von 1∶100, in 53 Fallen eine solche von 1∶500 positiv. Von 53 Kontrollseren waren nur 2 bei der Verdunnung von 1∶100 positiv. Hieraus wird auf das Vorkommen eines hitzestabilen gemeinsamen Gruppen-Antigens in Reiter-Treponemen und T. pallidum geschlossen. Die Zugehorigkeit dieses Antigens zu den Lipopolysacchariden wird diskutiert. Menschliche Antikorper gegen dieses Antigen sind vorerst nur fluorescenzserologisch nachzuweisen.
Solvent-trap reaction of triazolinediones with simple alkenes: An experimental/theoretical study of thermodynamic and kinetic parameters This work is…
2015
The reaction of N-phenyltriazolinedione with simple alkyl-substituted alkenes in a series of simple alcohols as nucleophilic solvents affords two products: a solvent-addition product (trap) and the ene adduct. Herein we present different experimental data which allow the estimation of different kinetic parameters (ΔΔH ≠ene,trap and ΔΔS ≠ene,trap ). The values of those parameters are found to be lower with a longer nucleophile-solvent molecule. Solvent isotope effects are also estimated and found in favour of the heavier (and smaller) deuterated compounds. Results from competition experiments in equimolar binary mixtures of different alcohols as solvents also point to the prevalence of the s…
Mg/BOX complexes as efficient catalysts for the enantioselective Michael addition of malonates to β-trifluoromethyl-α,β-unsaturated ketones and their…
2021
Abstract Magnesium (II)-BOX complexes catalyze the enantioselective Michael addition of malonates to β-trifluoromethyl enones and their N-sulfonyl imines to give ketones or (E)-enamines bearing a trifluoromethylated stereogenic center, respectively, with good yields and high enantiomeric excesses. Magnesium complexes proved to be more active and stereoselective than zinc and copper analogues in these reactions.
Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines
2017
[EN] Copper triflate-BOX complexes catalyse the enantioselective conjugate addition of methyl malonate to beta-trifluoromethyl-alpha,beta-unsaturated imines to give the corresponding enamines bearing a trifluoromethylated stereogenic centre with good yields, and diastereo- and enantioselectivities. The usefulness of the method has been shown with the synthesis of optically active beta-trifluoromethyl delta-amino esters and optically active trifluoromethyl piperidones.
Enantioselective Zirconium-Catalyzed Friedel−Crafts Alkylation of Pyrrole with Trifluoromethyl Ketones
2009
The first catalytic enantioselective Friedel-Crafts alkylation of pyrrole with 2,2,2-trifluoroacetophenones to give pyrroles with a trifluoromethyl-substituted tertiary alcohol moiety bearing a quaternary stereogenic center is described. The reaction is achieved in the presence of a 3,3'-dibromo-BINOL-Zr(IV) complex to give the expected products with high yields (up to 98%) and good enantioselectivities (up to 93% ee). The absolute stereochemistry of the products has been determined by chemical correlation.
Preparation and nonlinear optics of monodisperse oligo(1,4-phenyleneethynylene)s
2001
Oligo(1,4-phenyleneethynylene)s 1a−e, with solubilizing propoxy side chains, were prepared by use of Hagihara−Sonogashira coupling reactions. The synthetic strategy was based on a building block system and on the use of trimethylsilyl and triisopropylsilyl protecting groups that could be cleaved selectively. The extension of the conjugation with an increasing number of repeat units provokes a bathochromic shift of the long wavelength absorption and a superlinear increase of the second hyperpolarizability |γ|. The corresponding third harmonic generation (THG) measurements were performed using polystyrene matrices and variable laser wavelengths. We conclude that the conjugation length is much…
Multiple reaction monitoring for identification and quantification of oligosaccharides in legumes using a triple quadrupole mass spectrometer.
2022
Raffinose family oligosaccharides are non-digestible compounds considered as dietary prebiotics with health-related properties. Hence, it is important to develop highly specific methods for their determination. An analytical method is developed in this study for oligosaccharide identification and quantification using liquid chromatography-tandem mass spectrometry equipped with a triple quadrupole analyser operating in Multiple Reaction Monitoring mode. Raffinose, stachyose and verbascose are separated in a 10-minute run and the method is validated over a broad concentration range, showing good linearity, accuracy, precision and high sensitivity. A low-cost, short eco-friendly procedure for …