Spontaneous formation of bilayers and vesicles in mixtures of single-chain alkyl carboxylates: effect of pH and aging and cytotoxicity studies

We report the observation of bilayer fragments, some of which close to form vesicles, over a large range of pH at room temperature from mixtures of single-chain biocompatible commercially available nontoxic alkyl carboxylic surfactants after neutralization with HCl. The pH at which the morphological transitions occur is varied only by changing the ratio between two surfactants: the alkyloligoethyleneoxide carboxylate and sodium laurate. The effect of aging of the mixed surfactant systems in the pH region desired for dermatologic application (4.5 < pH < 7) is also studied. Finally, we show results of cytotoxicity studies on the surfactant mixtures.     

Fractal models of the shrinkage compensation mechanism for unsaturated polyesters

The shrinkage compensation mechanism in sheet molding compounds is governed by the morphology resulting from phase separation and microvoids formation. The observed microvoid morphology is quantified by using fractal geometry, in 2D and 3D spaces. The correlation between the morphologies of the matrix with phase separation and those of the microvoids is demonstrated by simulation. The pressure effect is studied. The fact that the shrinkage compensation has a pressure dependent optimum is explained by a model for the compensated volume. Thus, the “fractal pillar effect” is a model that represents properly speaking the compromise between pressure and volume creation shown by such a smart material.     

A Potent,Selective and Cell‐Active Allosteric Inhibitor of Protein Arginine Methyltransferase 3 (PRMT3)

PRMT3 catalyzes the asymmetric dimethylation of arginine residues of various proteins. It is essential for maturation of ribosomes, may have a role in lipogenesis, and is implicated in several diseases. A potent, selective, and cell‐active PRMT3 inhibitor would be a valuable tool for further investigating PRMT3 biology. Here we report the discovery of the first PRMT3 chemical probe, SGC707, by structure‐based optimization of the allosteric PRMT3 inhibitors we reported previously, and thorough characterization of this probe in biochemical, biophysical, and cellular assays. SGC707 is a potent PRMT3 inhibitor (IC₅₀=31±2 nM , K_D=53±2 nM ) with outstanding selectivity (selective against 31 other methyltransferases and more than 250 non‐epigenetic targets). The mechanism of action studies and crystal structure of the PRMT3‐SGC707 complex confirm the allosteric inhibition mode. Importantly, SGC707 engages PRMT3 and potently inhibits its methyltransferase activity in cells. It is also bioavailable and suitable for animal studies. This well‐characterized chemical probe is an excellent tool to further study the role of PRMT3 in health and disease.     

Attenuated Organomagnesium Activation of White Phosphorus

Sequential reactions between a 2,6‐diisopropylphenyl‐substituted β‐diketiminato magnesium n‐butyl derivative and P₄ allow the highly discriminating synthesis of unusual [nBu₂P₄]^2? and [nBu₂P₈]^2? cluster dianions.     

On the Stability of the Notion of Non-Characteristic Point and Blow-Up Profile for Semilinear Wave Equations

Communications in Mathematical Physics - We consider a blow-up solution for the semilinear wave equation in N dimensions, with subconformal power nonlinearity. Introducing $${mathcal{R}_0}$$ the...     

Development of the first well-defined tungsten oxo alkyl derivatives supported on silica by SOMC: towards a model of WO3/SiO2 olefin metathesis catalyst

A well-defined, silica-supported tungsten oxo alkyl species prepared by the surface organometallic chemistry approach displays high and sustained activity in propene metathesis. Remarkably, its catalytic performances outpace those of the parent imido derivative, underlining the importance of the oxo ligand in the design of robust catalysts.     

Guide to Semi-Quantitative Non-Targeted Screening Using LC/ESI/HRMS

Non-targeted screening (NTS) with reversed phase liquid chromatography electrospray ionization high resolution mass spectrometry (LC/ESI/HRMS) is increasingly employed as an alternative to targeted analysis; however, it is not possible to quantify all compounds found in a sample with analytical standards. As an alternative, semi-quantification strategies are, or at least should be, used to estimate the concentrations of the unknown compounds before final decision making. All steps in the analytical chain, from sample preparation to ionization conditions and data processing can influence the signals obtained, and thus the estimated concentrations. Therefore, each step needs to be considered carefully. Generally, less is more when it comes to choosing sample preparation as well as chromatographic and ionization conditions in NTS. By combining the positive and negative ionization mode, the performance of NTS can be improved, since different compounds ionize better in one or the other mode. Furthermore, NTS gives opportunities for retrospective analysis. In this tutorial, strategies for semi-quantification are described, sources potentially decreasing the signals are identified and possibilities to improve NTS are discussed. Additionally, examples of retrospective analysis are presented. Finally, we present a checklist for carrying out semi-quantitative NTS.