Choline chloride based deep eutectic solvents for the lignocellulose nanofibril production from Mongolian oak (Quercus mongolica)

Cellulose - Lignocellulose nanofibrils (LCNFs) were produced from the biomass of Mongolian oak for the first time using deep eutectic solvent pretreatment and mechanical defibrillation. Three...     

Effect of heterocyclic ring system on formation of dimeric quinolones under catalyst-free conditions: a green approach

The intermediate-dependent green and efficient synthesis of dimeric quinolones 4a–l and 7a–l by the Knoevenagel condensation followed by Michael-type addition of 4-hydroxy-1-methylquinolin-2(1H)-one 1a, b to indole-3-aldehydes 2a–f and aromatic aldehydes 5a–l in water through the condensed compound 3a–l under catalyst-free conditions is described. This reaction was found to be environmentally friendly, has easy-workup and shorter reaction times giving good yields of the product without the need for its isolation using column chromatography.     

Adsorption and reversed-phase high-performance liquid chromatography of p-nitrobenzyl esters of monohydroxy fatty acids

To enhance the UV detectability of hydroxy fatty acids, p-nitrobenzyl (PNB) esters of twenty-two different monohydroxy fatty acids of various chain-lengths (C16-C22) and differing positional isomers were formed using O-(p-nitrobenzyl)-N,N-(diisopropyl)-isourea (PNBDI) as alkylating agent. Reversed-phase and adsorption high-performance liquid chromatography (HPLC) of the twenty-two monohydroxy fatty acid PNB esters were studied. The PNB group did not dominate the chromatographic properties of monohydroxy fatty acids and it did not interfere with the HPLC separation of positional isomers. PNBDI was, however, found to be less than ideal for formation of PNB derivatives of monohydroxy fatty acids because UV absorbing contaminants of PNBDI interfered with the HPLC analyses.     

Test of the Fluctuation Relation in Lagrangian Turbulence on a Free Surface

The statistics of velocity divergence are studied for an assembly of particles that float on a closed turbulent fluid. Under an appropriate definition of entropy, the two-dimensional Lagrangian velocity divergence of a particle trajectory represents the local entropy rate , a random variable in time. The statistics of this rate, measured in the Lagrangian frame, are collected over a wide range of values. This permits a severe test of the fluctuation relation (FR) over a range that exceeds prior experiments, out to a regime beyond which the FR no longer holds. Notably, the probability density functions (PDF) of the dimensionless divergence σ _τ are strongly non-Gaussian. This work was supported by the National Science Foundation under grant number DMR-0201805.     

Sobralene,a new sex-aggregation pheromone and likely shunt metabolite of the taxadiene synthase cascade,produced by a member of the sand fly Lutzomyia longipalpis species complex

A new sex-aggregation pheromone, sobralene, produced by the sand fly Lutzomyia longipalpis from Sobral (Ceará State, Brazil) is shown to have the novel 6,12-membered ring-fused diterpene structure 3. It is proposed that sobralene is a likely shunt metabolite of the taxadiene synthase-catalysed cyclisation of geranygeranyl diphosphate.     

Probing the bottom of a folding funnel using conformationally gated electron transfer reactions

The effect of global stability on the kinetics of interconversion between the native (N) and a compact, partially unfolded form (I) of iso-1-cytochrome c stabilized by His73-heme ligation is investigated using a novel conformationally gated ET method. For the K73H variant and the 2-fold less stable AcH73 variant, the N and I conformers are of nearly equal stability at pH 7.5. The pH jump kinetic data yield kobs = kNI + kIN of 35-40 s-1 at final pH values from 6 to 8 for the AcH73 variant, about 3-fold faster than for the more stable K73H variant. Gated ET measurements give kNI = 28 s-1 and kIN = 13 s-1 for the AcH73 variant, 10- and 2-fold greater than that for the more stable K73H variant. Thus, funneled landscapes have evolved such that loss of global stability lowers barriers at the bottom of a folding funnel, still allowing for efficient folding.     

Where surface physics and fluid dynamics meet: rupture of an amphiphile layer by fluid flow

We investigate the fluctuating pattern created by a jet of fluid impingent upon an amphiphile-covered surface. This microscopically thin layer is initially covered with 50 microm floating particles so that the layer can be visualized. A vertical jet of water located below the surface and directed upward drives a hole in this layer. The hole is particle-free and is surrounded by the particle-laden amphiphile region. The jet ruptures the amphiphile layer creating a particle-free region that is surrounded by the particle-covered surface. The aim of the experiment is to understand the (fluctuating) shape of the ramified interface between the particle-laden and particle-free regions.     

Polyphenolics profile and antioxidant properties of Raphanus sativus L

Raphanus sativus, a common cruciferous vegetable has been attributed to possess a number of pharmacological properties. Antioxidant and radical scavenging activity of R. sativus root extracted with solvents of varying polarity were evaluated using different model systems. Polyphenolic content was estimated to be in the range 13.18-63.54?mg?g?1 dry weight, with a considerable amount being obtained with polar solvents. High-performance liquid chromatography analysis indicated the presence of an array of polyphenolics. Catechin was found to be the most abundant phenolic compound in water extract and sinapic acid, the predominant phenolic compound in methanolic, ethyl acetate and hexane extracts. The methanolic extract showed significant ferric reducing ability, moderate metal chelating activity and strong radical scavenging activity. The methanolic extract could be successfully utilised as an ingredient in functional foods. However, water extract could be more pertinent to human nutrition as it contained a significant amount of catechin, which was comparable to traditional sources like green and black tea.