On the complexation of quercetin with methyl-??-cyclodextrin: photostability and antioxidant studies

Quercetin, a plant-derived flavonoid, has been extensively investigated for a wide range of potential health benefits linked to its antioxidant properties. Unfortunately the topical administration of this molecule is restricted by its fast photodegradation. In the attempt to overcome this limitation the inclusion complex between quercetin (Q) and methyl-??-cyclodextrin (Me-??-CD) was prepared and previously investigated by a molecular modelling study, a solubility diagram and a DSC analysis. Successively the kinetics of photodegradation, the antiradical, metal chelating and anti-lipoperoxidative activities were studied by comparing the complex with free Q. In addition the accumulation of Q in porcine skin was evaluated after in vitro topical application by means of vertical Franz cells. The complex formation resulted useful in enhancing the solubility of Q without significantly reducing its antioxidant ability. A modest improvement in the photostability was also observed.     

Small Changes Have Consequences: Lessons from Tetrabenzyltitanium and ‐zirconium Surface Organometallic Chemistry

Homoleptic benzyl derivatives of titanium and zirconium have been grafted onto silica that was dehydroxylated at 200 and 700 °C, thereby affording bi‐grafted and mono‐grafted single‐site species, respectively, as shown by a combination of experimental techniques (IR, MAS NMR, EXAFS, and elemental analysis) and theoretical calculations. Marked differences between these compounds and their neopentyl analogues are discussed and rationalized by using DFT. These differences were assigned to the selectivity of the grafting process, which, depending on the structure of the molecular precursors, led to different outcomes in terms of the mono‐ versus bi‐grafted species for the same surface concentration of silanol species. The benzylzirconium derivatives were active towards ethylene polymerization in the absence of an activator and the bi‐grafted species displayed higher activity than their mono‐grafted analogues. In contrast, the benzyltitanium and neopentylzirconium counterparts were not active under similar reaction conditions.     

Schmelztiegel von Magnesia

Ohne Zusammenfassung     

Usefulness of autoantigens depletion to detect autoantibody signatures by multiple affinity protein profiling

Patients with cancer produce specific autoantibodies against protein antigens present in limited amount among a large background of immunoglobulins (Igs), nonrelevant as biomarkers, including natural antibodies. Multiple affinity protein profiling (MAPPing) that combines 2-D immunoaffinity chromatography, enzymatic digestion of the isolated proteins, and identification by MS/MS, may facilitate the identification of these so far unknown patient antibodies. The first immunoaffinity chromatography is crucial, as it is used for selectively removing proteins (autoantigens) recognized by natural antibodies. Application of this depletion step to colon cancer cell proteins is specifically described along with the identification of the natural autoantigens, as well as the coupling of this depletion step with the next steps. By enabling to separate antibody-binding proteins recognized by either natural autoantibodies or patient-specific antibodies this approach may contribute significantly towards the definition of autoantibody signatures.     

Dramatic increase of quench efficiency in "spacerless" dimaleimide fluorogens

In this post-genomic era, new techniques are needed to cope with the task of assigning functional roles to the huge number of identified putative gene products. We have developed a minimalist labelling strategy based on the use of synthetic fluorogenic probe reagents that fluoresce only after their reaction with a target peptide sequence. The probe reagents have fluorescent cores and bear two maleimide groups, such that their latent fluorescence is quenched by a photoinduced electron transfer (PET) to the pendant maleimide groups, until both of these groups undergo a specific thiol addition reaction. The efficiency of the fluorescence quenching is critical to the practicality of this labelling method, and has been predicted to be related to the intramolecular distance between the fluorophore and the maleimide groups. We have conducted the first direct test of this hypothesis by preparing a series of novel fluorogens that differ only by the spacer moiety separating their coumarin fluorophore and their dimaleimide fragment. A striking correlation was observed between intramolecular distance and the fluorescence enhancement (FE) observed after reaction with two equivalents of thiol. Guided by this observation, we then designed 'spacerless' fluorogens, of which a dansyl derivative shows an FE ratio of >300, the largest recorded for dimaleimide fluorogens. The trends observed herein provide valuable lessons for subsequent fluorogen design, and the novel fluorogens developed in the course of this study are currently being applied to protein labelling applications.     

Detecting high-dimensional determinism in time series with application to human movement data

We numerically investigate the ability of a statistic to detect determinism in time series generated by high-dimensional continuous chaotic systems. This recently introduced statistic (denoted V_E2) is derived from the averaged false nearest neighbors method for analyzing data. Using surrogate data tests, we show that the proposed statistic is able to discriminate high-dimensional chaotic data from their stochastic counterparts. By analyzing the effect of the length of the available data, we show that the proposed criterion is efficient for relatively short time series. Finally, we apply the method to real-world data from biomechanics, namely postural sway time series. In this case, the results led us to exclude the hypothesis of nonlinear deterministic underlying dynamics for the observed phenomena.     

OpenCDLig: a free web application for sharing resources about cyclodextrin/ligand complexes

OpenCDLig (freely available at ) implements a repository of complexes formed by cyclodextrins (CDs) and ligands (L) with related experimental data and make it available by an easy to use web interface. At the present time, the application supports two kinds of data: K, the association constant of a CD/L complex in [M⁻¹] and 3D structures in mol2 format. OpenCDLig is meant to become a community maintained source of experimental resources related to cyclodextrin complexes.     

The BSM-AI project: SUSY-AI–generalizing LHC limits on supersymmetry with machine learning

A key research question at the Large Hadron Collider is the test of models of new physics. Testing if a particular parameter set of such a model is excluded by LHC data is a challenge: it requires time consuming generation of scattering events, simulation of the detector response, event reconstruction, cross section calculations and analysis code to test against several hundred signal regions defined by the ATLAS and CMS experiments. In the BSM-AI project we approach this challenge with a new idea. A machine learning tool is devised to predict within a fraction of a millisecond if a model is excluded or not directly from the model parameters. A first example is SUSY-AI, trained on the phenomenological supersymmetric standard model (pMSSM). About 300, 000 pMSSM model sets – each tested against 200 signal regions by ATLAS – have been used to train and validate SUSY-AI. The code is currently able to reproduce the ATLAS exclusion regions in 19 dimensions with an accuracy of at least \(93\%\). It has been validated further within the constrained MSSM and the minimal natural supersymmetric model, again showing high accuracy. SUSY-AI and its future BSM derivatives will help to solve the problem of recasting LHC results for any model of new physics. SUSY-AI can be downloaded from http://susyai.hepforge.org/. An on-line interface to the program for quick testing purposes can be found at http://www.susy-ai.org/.     

Direct and Indirect Determination of the Magnetocaloric Effect in the Heusler Compound Ni1.7Pt0.3MnGa

Magnetic shape-memory materials are potential magnetic refrigerants, due the caloric properties of their magnetic-field-induced martensitic transformation. The first-order nature of the martensitic transition may be the origin of hysteresis effects that can hinder practical applications. Moreover, the presence of latent heat in these transitions requires direct methods to measure the entropy and to correctly analyze the magnetocaloric effect. Here, we investigated the magnetocaloric effect in the Heusler material Ni1.7Pt0.3MnGa by combining an indirect approach to determine the entropy change from isofield magnetization curves and direct heat-flow measurements using a Peltier calorimeter. Our results demonstrate that the magnetic entropy change ΔS in the vicinity of the first-order martensitic phase transition depends on the measuring method and is directly connected with the temperature and field history of the experimental processes.