Ascorbic acid modulates the structure of the virulence factor pyocyanin and ascorbic acid-furanone-30 combination facilitate biofilm disruption.

The production of pyocyanin by increases its virulence, fitness and biofilm formation. Pyocyanin is also a redox molecule and we hypothesize that ascorbic acid being an antioxidant will interact with pyocyanin. The main objective of this study was to investigate the potential interaction of ascorbic acid with pyocyanin, and also to investigate the impact of ascorbic acid in combination with Furanone-30 on quorum sensing and biofilm formation of .

Effective PFAS degradation by electrochemical oxidation methods-recent progress and requirement.

The presence of per- and poly-fluoroalkyl substances (PFASs) in water is of global concern due to their high stability and toxicity even at very low concentrations. There are several technologies for the remediation of PFASs, but most of them are inadequate either due to limited effectiveness, high cost, or production of a large amount of sludge. Electrochemical oxidation (EO) technology shows great potential for large-scale application in the degradation of PFASs due to its simple procedure, low loading of chemicals, and least amount of waste.

Ruthenium containing molecular electrocatalyst on glassy carbon for electrochemical water splitting.

Electrochemical water splitting constitutes one of the most promising strategies for converting water into hydrogen-based fuels, and this technology is predicted to play a key role in the transition towards a carbon-neutral energy economy. To enable the design of cost-effective electrolysis cells based on this technology, new and more efficient anodes with augmented water splitting activity and stability will be required. Herein, we report an active molecular Ru-based catalyst for electrochemically-driven water oxidation (overpotential of ∼395 mV at pH 7 phosphate buffer) and two simple methods for preparing anodes by attaching this catalyst onto glassy carbon through multi-walled carbon nanotubes to improve stability as well as reactivity.

Effect of airborne-particle abrasion with a novel spherical abrasive on the zirconia surface.

Statement Of Problem: A novel zirconia-alumina composite (ZAC) particle has yet to be studied for airborne-particle abrasion in a bonding protocol for the zirconia surface.

Purpose: The purpose of this in vitro study was to evaluate the shear bond force of resin cement to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) when using spherical ZAC particles to conduct airborne-particle abrasion and modify the topography of Y-TZP.

Material And Methods: Spherical 30- to 70-μm ZAC particles were fabricated by using a hybrid gel technique.

Sustainable Design for the Direct Fabrication and Highly Versatile Functionalization of Nanocelluloses.

This study describes a novel sustainable concept for the scalable direct fabrication and functionalization of nanocellulose from wood pulp with reduced energy consumption. A central concept is the use of metal-free small organic molecules as mediators and catalysts for the production and subsequent versatile surface engineering of the cellulosic nanomaterials via organocatalysis and click chemistry. Here, "organoclick" chemistry enables the selective functionalization of nanocelluloses with different organic molecules as well as the binding of palladium ions or nanoparticles.

Mild and selective Et2Zn-catalyzed reduction of tertiary amides under hydrosilylation conditions.

Diethylzinc (Et2Zn) can be used as an efficient and chemoselective catalyst for the reduction of tertiary amides under mild reaction conditions employing cost-effective polymeric silane (PMHS) as the hydride source. Crucial for the catalytic activity was the addition of a substoichiometric amount of lithium chloride to the reaction mixture. A series of amides containing different additional functional groups were reduced to their corresponding amines, and the products were isolated in good-to-excellent yields.

Mo(CO)6 catalysed chemoselective hydrosilylation of α,β-unsaturated amides for the formation of allylamines.

Molybdenum hexacarbonyl (Mo(CO)6) was used as an efficient catalyst for the chemoselective reduction of the amide functionality in α,β-unsaturated compounds, under hydrosilylation conditions using 1,1,3,3-tetramethyldisiloxane (TMDS) as the hydride source.

Investigation of the impact of water on the enantioselectivity displayed by CALB in the kinetic resolution of δ-functionalized alkan-2-ol derivatives.

It is shown that the low enantioselectivity of Candida antarctica lipase B (CALB)-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity of the CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation is unusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation between the enantioselectivity of transesterification of the alcohol and hydrolysis of the corresponding acetate (E>200 in both cases). The results confirm previous predictions from molecular modeling.

NMR investigation of chloromethane complexes of cryptophane-A and its analogue with butoxy groups.

Host-guest complexes between cryptophane-A as host and dichloromethane and chloroform as guests are investigated using (1)H and (13)C NMR spectroscopy. Moreover, a related cryptophane, with the methoxy groups replaced by butoxy units (cryptophane-But), and its complexes with the same guests were also studied. Variable temperature spectra showed effects of chemical exchange between the free and bound guests, as well as of conformational exchange of the host.

Employing the structural diversity of nature: development of modular dipeptide-analogue ligands for ruthenium-catalyzed enantioselective transfer hydrogenation of ketones.

A library of novel dipeptide-analogue ligands based on the combination of tert-butoxycarbonyl(N-Boc)-protected alpha-amino acids and chiral vicinal amino alcohols were prepared. These highly modular ligands were combined with [[RuCl(2)(p-cymene)](2)] and the resulting metal complexes were screened as catalysts for the enantioselective reduction of acetophenone under transfer hydrogenation conditions using 2-propanol as the hydrogen donor. Excellent enantioselectivity of 1-phenylethanol (up to 98 % ee) was achieved with several of the novel catalysts.

A test for the number of coupled spins I = 1/2 in magic-angle-spinning solids: zero-quantum recoupling of multiple-quantum coherences.

Current methodologies for estimating the number of coupled spins I = 1/2 in solids are based upon the maximum multiple-quantum order that can be observed. This strategy establishes a clear lower bound on the number of coupled spins I = 1/2. However, it is difficult to ascertain the exact number of coupled spins, since the absence of a peak could be due either to the limited size of the spin system or to the experimental difficulty of exciting high-quantum orders and recovering those coherences into detectable signals.

Synthesis of an amino-functionalized model of the Fe-only hydrogenase active site.

A dinuclear 2Fe2S mimic 6 of the active site of the Fe-only hydrogenases has been synthesized. Complex 6 contains a free amino group which enables linkage to a protein backbone or to a redox active species for the study of electron transfer processes in proteins or in supramolecular systems. The structures of the complex 6 and its Boc-protected precursor 5 could be verified by X-ray crystallography.

Studies on the mechanism of metal-catalyzed hydrogen transfer from alcohols to ketones.

The mechanism of metal-catalyzed hydrogen transfer from alcohols to ketones has been studied. Hydrogen transfer (H-transfer) from (S)-alpha-deutero-alpha-phenylethanol ((S)-1) to acetophenone was used as a probe to distinguish between selective carbon-to-carbon H-transfer and nonselective transfer involving both oxygen-to-carbon and carbon-to-carbon H-transfer. The progress of the reaction was monitored by the decreasing enantiomeric excess of (S)-1.

Structure of Ca Cd : A Novel Approximant to the MCd Quasicrystals (M=Ca, Yb).

The closest cubic approximant to the MCd (M = Ca, Yb) quasicrystals known so far, namely Ca Cd , was obtained by high-temperature reaction of the elements. It exhibits a new type of structure for intermetallic compounds with an unprecedented arrangement of triacontahedral clusters, which could prove useful in modeling the structures of the MCd quasicrystals.

Oligosaccharides display both rigidity and high flexibility in water as determined by 13C NMR relaxation and 1H,1H NOE spectroscopy: evidence of anti-phi and anti-psi torsions in the same glycosidic linkage.

The trisaccharide beta-D-Glcp-(1-->2)-beta-D-Glcp-(1-->3)-alpha-D-Glcp-OMe has been investigated by molecular dynamics (MD) simulations and NMR experiments in water. 13C spin-lattice (T1) and spin-spin (T2) relaxation times, together with 1H,13C NOE data were measured at two magnetic field strengths (9.4 and 14.

Conformational analysis of methyl 6-O-[(R)- and (S)-1-carboxyethyl]-alpha-D-galactopyranoside by MM and Langevin dynamics simulations.

The conformational space of methyl 6-O-[(R)- and (S)-1-carboxyethyl]-alpha-D-galactopyranoside has been investigated. A grid search employing energy minimization at each grid point over the three major degrees of freedom, namely phi, psi and omega, identified low energy regions. The R-isomer shows five low energy conformers within ca.