Machine learning for in silico virtual screening and chemical genomics: new strategies

Support vector machines and kernel methods belong to the same class of machine learning algorithms that has recently become prominent in both computational biology and chemistry, although both fields have largely ignored each other. These methods are based on a sound mathematical and computationally efficient framework that implicitly embeds the data of interest, respectively proteins and small molecules, in high-dimensional feature spaces where various classification or regression tasks can be performed with linear algorithms. In this review, we present the main ideas underlying these approaches, survey how both the "biological" and the "chemical" spaces have been separately constructed using the same mathematical framework and tricks, and suggest different avenues to unify both spaces for the purpose of in silico chemogenomics.     

Reversible folding-unfolding, aggregation protection, and multi-year stabilization, in high concentration protein solutions, using ionic liquids

We report the reversible thermal unfolding/refolding, and long period stabilization against aggregation and hydrolysis, of >200 mg ml(-1) solutions of lysozyme in ionic liquid-rich, ice-avoiding, solvents.     

Non-invasive single bunch monitoring for ps pulse radiolysis

A single-shot electro-optic (EO) diagnostic has been installed on the ELYSE photocathode RF gun accelerator to monitor the electron bunch at the place and under the conditions of the ps pulse radiolysis experiments. The EO signal is due to the coulombic field of the electron bunch and to a contribution of a free-space THz radiation generated by the same electron pulse. This signal is recorded shot-to-shot at the repetition rate of the accelerator. The jitter of the arrival time of the electron bunch is characterized for the first time with a non-invasive method and is confirmed to be around 1 ps.     

Excitation emission and time-resolved fluorescence spectroscopy of selected varnishes used in historical musical instruments

The analysis of various varnishes from different origins, which are commonly found on historical musical instruments was carried out for the first time with both fluorescence excitation emission spectroscopy and laser-induced time-resolved fluorescence spectroscopy. Samples studied include varnishes prepared using shellac, and selected diterpenoid and triterpenoid resins from plants, and mixtures of these materials. Fluorescence excitation emission spectra have been collected from films of naturally aged varnishes. In parallel, time-resolved fluorescence spectroscopy of varnishes provides means for discriminating between short- (less than 2.0 ns) and long-lived (greater than 7.5 ns) fluorescence emissions in each of these complex materials. Results suggest that complementary use of the two non destructive techniques allows a better understanding of the main fluorophores responsible for the emission in shellac, and further provides means for distinguishing the main classes of other varnishes based on differences in fluorescence lifetime behaviour. Spectrofluorimetric data and time resolved spectra presented here may form the basis for the interpretation of results from future in situ fluorescence examination and time resolved fluorescence imaging of varnished musical instruments.     

Chiral Brønsted acid-catalyzed diastereo- and enantioselective synthesis of CF(3)-substituted aziridines

A multicomponent organocatalyzed highly diastereo- and enantioselective synthesis of CF(3)-substituted aziridines is described. This reaction of in situ generated CF(3)CHN(2) and aldimines was realized by chiral Br?nsted acid catalysis. The utility of the products is illustrated by easy access to β-CF(3) isocysteine and aziridine-containing dipeptides.     

Monomeric Sn(II) and Ge(II) hydrides supported by a tridentate pincer-based ligand

Herein we report the syntheses of terminal Sn(II) (3) and Ge(II) (4) hydrides from the corresponding chloride precursors [{2,6-iPr(2)C(6)H(3)NCMe}(2)C(6)H(3)MCl] (M = Sn (1), Ge (2)) using [K{B(sec-Bu)(3)}H] as a hydrogenating agent. Combination of steric shielding and intramolecular N → M interactions resulted in the protection of M(II)-H bonds.