Selective Detection of Choline in Pseudophysiological Medium with a Fluorescent Cage Receptor.

A fluorescent cage receptor for the detection of choline in pseudophysiological medium is described. Not only does this capsule complex choline with an association constant greater than 9.9 × 10 M in buffered medium but it is also selective toward acetylcholine.

Volatile fingerprint of food products with untargeted SIFT-MS data coupled with mixOmics methods for profile discrimination: Application case on cheese.

Volatile organic compounds (VOCs) emitted by food products are decisive for the perception of aroma and taste. The analysis of gaseous matrices is traditionally done by detection and quantification of few dozens of characteristic markers. Emerging direct injection mass spectrometry technologies offer rapid analysis based on a soft ionisation of VOCs without previous separation.

Tissue localization of selenium of parental or dietary origin in rainbow trout (Oncorhynchus mykiss) fry using LA-ICP MS bioimaging.

In relation to the decrease of selenium (Se) content in aquafeeds, the impact of level and form of parental and dietary Se supplementation was investigated in rainbow trout fry using laser ablation-inductively coupled plasma mass spectrometry (LA-ICP MS) bioimaging. The offspring of rainbow trout broodstock, fed either a control diet without any Se supplementation (0.3 mg Se/kg diet) or a diet supplemented with Se (0.

Redox activity of nickel and vanadium porphyrins: a possible mechanism behind petroleum genesis and maturation?

The presence of metalloporphyrins in crude oil has been known for many years. In contrast, their role on the physical-chemical properties is only now beginning to be understood. In this study, we test using high-level calculations, the hypothesis of a possible redox catalytic activity of vanadium and nickel metalloporphyrins in crude oil, illustrated by the oxidation of methanol to formaldehyde and hydrogen dissociation, respectively.

Surface Reactivity of LiMnO: First-Principles and Experimental Study.

This article deals with the surface reactivity of (001)-oriented LiMnO crystals investigated from a multitechnique approach combining material synthesis, X-ray photoemission spectroscopy (XPS), scanning electron microscopy, Auger electron spectroscopy, and first-principles calculations. LiMnO is considered as a model compound suitable to go further in the understanding of the role of tetravalent manganese atoms in the surface reactivity of layered lithium oxides. The knowledge of the surface properties of such materials is essential to understand the mechanisms involved in parasitic phenomena responsible for early aging or poor storage performances of lithium-ion batteries.

First-principle calculation of core level binding energies of LixPOyNz solid electrolyte.

We present first-principle calculations of core-level binding energies for the study of insulating, bulk phase, compounds, based on the Slater-Janak transition state model. Those calculations were performed in order to find a reliable model of the amorphous LixPOyNz solid electrolyte which is able to reproduce its electronic properties gathered from X-ray photoemission spectroscopy (XPS) experiments. As a starting point, Li2PO2N models were investigated.

Excited State Dynamics of the Green Fluorescent Protein on the Nanosecond Time Scale.

We have introduced a new algorithm in the parallel processing PMEMD module of the AMBER suite that allows MD simulations with a potential involving two coupled torsions. We have used this modified module to study the green fluorescent protein. A coupled torsional potential was adjusted on high accuracy quantum chemical calculations of the anionic chromophore in the first excited state, and several 15-ns-long MD simulations were performed.

Relation between pH, structure, and absorption spectrum of Cerulean: a study by molecular dynamics and TD DFT calculations.

Molecular dynamics (MD) and quantum mechanical calculations of the Cerulean green fluorescent protein (a variant of enhanced cyan fluorescent protein ECFP) at pH 5.0 and 8.0 are presented, addressing two questions arising from experimental results (Malo et al.

Complex fluorescence of the cyan fluorescent protein: comparisons with the H148D variant and consequences for quantitative cell imaging.

We have studied the fluorescence decays of the purified enhanced cyan fluorescent protein (ECFP, with chromophore sequence Thr-Trp-Gly) and of its variant carrying the single H148D mutation characteristic of the brighter form Cerulean. Both proteins exhibit highly complex fluorescence decays showing strong temperature and pH dependences. At neutral pH, the H148D mutation leads (i) to a general increase in all fluorescence lifetimes and (ii) to the disappearance of a subpopulation, estimated to be more than 25% of the total ECFP molecules, characterized by a quenched and red-shifted fluorescence.

Cyan fluorescent protein: molecular dynamics, simulations, and electronic absorption spectrum.

The dynamics and electronic absorption spectrum of enhanced cyan fluorescent protein (ECFP), a mutant of green fluorescent protein (GFP), have been studied by means of a 1 ns molecular dynamics (MD) simulation. The two X-ray conformations A' and B' of ECFP were considered. The chromophore was assumed to be neutral, and all titratable residues were taken in their standard protonation state at neutral pH.