Palladium-catalyzed Ullmann-type reductive homocoupling of iodoaryl glycosides

A catalytic synthesis of novel biaryl-linked divalent glycosides was achieved using an electroreductive palladium-catalyzed iodoaryl-iodoaryl coupling reaction. This new method was optimized for the synthesis of divalent biaryl-linked mannopyranosides that was subsequently generalized toward several carbohydrate substrates with yields up to 96%.     

Structural features of mono- and tri-nuclear Zn(II) complexes with a non-steroidal anti-inflammatory drug as ligand

The interaction of Zn(II) with the non-steroidal anti-inflammatory drug tolfenamic acid leads to the formation of the structurally characterized trinuclear [Zn(3)(tolfenamato)(6)(CH(3)OH)(2)] complex. In the presence of the N,N'-donor heterocyclic ligands 1,10-phenanthroline and 2,2'-bipyridine at a range of ratios, the mononuclear Zn complexes of the general formulae [Zn(tolfenamato)(N,N'-donor)Cl] and [Zn(tolfenamato)(2)(N,N'-donor)] have been isolated and structurally characterized by X-ray crystallography. The deprotonated tolfenamato ligands are coordinated to the Zn(II) ion through carboxylato oxygen atoms. Tolfenamic acid and its complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.     

Dondorff rings: synthesis, isolation, and properties of 60°-directed bisterpyridine-based folded tetramers

Square feat: The synthesis, isolation, and characterization of five novel bisterpyridine-based metallomacrocycles, possessing a folded tetrameric configuration is reported. The initial dimeric building block with the stable linear {tpy-Ru(II) -tpy} connectivity circumvents the formation of the thermodynamically favored molecular triangles.     

Characterization of surface and porous properties of synthetic hybrid lamellar silica

Synthetic lamellar silica and hybrid lamellar silicas have been prepared by liquid crystal templating, template extraction and silanization. The samples have been characterized by thermogravimetric analysis (TGA), carbon analysis, spectroscopy, X-ray diffraction (XRD) and nitrogen adsorption. The XRD analyses have shown that the lamellar periodic stacking is preserved for all samples. The quantity and type of organic molecules at the silica surface have been evaluated by carbon analysis, TGA and spectroscopy. The covalent grafting of the solvent used for extraction of the initial surfactant has been highlighted by these analyses. The nitrogen adsorption analyses have revealed three categories of pores and two types of samples. The initial lamellar silica exhibits a very low specific surface area and plate-like type of pores. The second type of samples is made up of the hybrid samples and the initial substrate from whom the surfactant has been extracted. These samples show a significantly higher specific surface area with interlamellar spaces corresponding to narrow-slit like mesopores around 4 nm. The nitrogen adsorption data analysis has highlighted the presence of micropores within the silica sheets. The difference of the specific surface is due to pore blocking by the surfactant impeding the access to nitrogen into interlamellar spaces and by the silanes covering the pores once the surface modified. The presence of micro and mesopores combined to a high BET specific surface of 612 m²/g makes these lamellar silicas interesting materials for catalysis applications.     

High pressure matrix-assisted laser desorption/ionization Fourier transform mass spectrometry for minimization of ganglioside fragmentation

Transiently elevating pressure in a matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) source into the 1-10 mbar range during ionization decreases the metastable fragmentation of gangliosides. This allows detection of the molecular ion species without loss of the highly labile sialic acid residues. In these experiments, gangliosides with up to five sialic acids were ionized by MALDI and detected with the FTMS. In each case, when the high pressure collisional cooling was used, the singly charged molecular ion was the base peak in the spectra, both in the positive and negative ion modes, and minimal metastable fragmentation was observed. This result is promising, as the previously developed TLC separation methods can be coupled to MALDI-FTMS.     

The thermochemistry of group 15 tetrachloride anions

Bond strengths for a series of Group 15 tetrachloride anions ACl4 (A = P, As, Sb, and Bi) have been determined by measuring thresholds for collision-induced dissociation of the anions in a flowing afterglow-tandem mass spectrometer. The central atoms in these systems have ten electrons, which violates the octet rule: the bond dissociation energies for ACl4- help to clarify the effect of the central atom on hypervalent bond strengths. The 0 K bond energies in kJ mol(-1) are D(Cl3A-CL-) = 90 +/- 7,115 +/- 7,161 +/- 8, and 154 +/- 15, respectively. Computational results using the B3LYP/LANL2DZpd level of theory are higher than the experimental bond energies. Calculations give a geometry for BiCl4 that is essentially tetrahedral rather than the see-saw observed for the other tetrachlorides. NBO calculations predict that the phosphorus and arsenic systems have 3C-4E bonds, while the antimony and bismuth systems are more ionic.     

Characterization of zinc hydroxynitrates by diffuse reflectance infrared spectroscopy--structural modifications during thermal treatment

Four zinc hydroxynitrates are known, but only the Infrared spectrum of Zn5(OH)8(NO3)2.2H2O is reported in the literature. Here, we report the IR spectra of the other three zinc hydroxynitrates, namely Zn(OH)(NO3).H2O, Zn3(OH)4(NO3)2 and Zn5(OH)8(NO3)2. The positions of the bands of the nitrate groups between 1000 and 1600 cm(-1) are discussed in relation to the structure of these compounds. The modifications of these IR spectra with temperature are consistent with previous studies on the thermal decomposition of these compounds.     

Image quality and diagnostic performance of silicone-specific breast MRI

Purpose

To compare the image quality of three techniques and diagnostic performance in detecting implant rupture.

Materials and Methods

The study included 161 implants for the evaluation of image quality, composed of water-saturated short TI inversion recovery (herein called “water-sat STIR”), three-point Dixon techniques (herein called “Dixon”), and short TI inversion recovery fast spin-echo with iterative decomposition of silicone and water using least-squares approximation (herein called “STIR IDEAL”) and included 41 implants for the evaluation of diagnostic performance in detecting rupture, composed of water-sat STIR and STIR IDEAL.Six image quality categories were evaluated and three classifications were used: normal implant, possible rupture, and definite rupture.

Results

Statistically significant differences were noted for the image quality categories (p < 0.001). STIR IDEAL was superior or equal to water-sat STIR in all image quality categories except artifact effects and superior to Dixon in all categories. Water-sat STIR performed the poorest for water suppression uniformity.The sensitivity and specificity in detecting implant rupture of STIR-IDEAL were 81.8 % and 77.8 % and the difference between two techniques was not statistically significant.

Conclusion

STIR-IDEAL is a useful silicone-specific imaging technique demonstrating more robust water suppression and equivalent diagnostic accuracy for detecting implant rupture, than water-sat STIR, at the cost of longer scan time and an increase in minor motion artifacts.     

Reciprocal Response of Human Oral Epithelial Cells to Internalized Silica Nanoparticles

Silica nanoparticles (SiO₂ NPs) are one of the most widely used engineered nanoparticles and can been found in a wide range of consumer products. Despite their massive global production scale, little is known about their potential effects in the context of unintended exposure or ingestion. Using TR146 cells as an in vitro model of the human oral buccal mucosa, the uptake, spatial intracellular distribution, reactive oxygen species (ROS) production, inflammatory response, and cytotoxic effects of commercial SiO₂ NPs are examined. SiO₂ NPs are shown to dock and cross the cellular membrane barrier in a dose–time‐dependent manner. Confocal sectioning reveals translocation of SiO₂ NPs into the cell nucleus after 12 h of exposure. A concentration threshold of more than 500 × 10^?6 m is observed, above which SiO₂ NPs are shown to exert significant oxidative stress with concomitant upregulation of inflammatory genes IL6 and TNFA. Further analysis of the p53 pathway and a series of apoptotic and cell cycle biomarkers reveals intracellular accumulation of SiO₂ NPs exert marginal nanotoxicity. Collectively, this study provides important information regarding the uptake, intracellular distribution, and potential adverse cellular effects of SiO₂ NPs commonly found in consumer products in the human oral epithelium.