Resonant two-photon two-color photoionization (R2P2CI) spectra of aniline-Ar n clusters: Isomer strutures and solvent shifts

We present resonant two-photon two-color photoionization (R2P2CI) spectra of a series of Aniline-Ar _n complexes (n=1?6). An apparently anomalous blue shifted spectra for An-Ar₃ is explained by a modified spectral shift additivity rule which assigns different shifts to different relative positions of the Ar with respect to aniline. Evidence is presented for the existence of several isomers of clusters withn≧2. It is shown that, by changing the nucleation conditions, it is possible to control the relative populations of the various isomers.     

Towards the experimental clarification of quarkonium polarization

We highlight issues which are often underestimated in the experimental analyses on quarkonium polarization: the relation between the parameters of the angular distributions and the angular momentum composition of the quarkonium, the importance of the choice of the reference frame, the interplay between observed decay and production kinematics, and the consequent influence of the experimental acceptance on the comparison between experimental measurements and theoretical calculations. Given the puzzles raised by the available experimental results, new measurements must provide more detailed information, such that physical conclusions can be derived without relying on model-dependent assumptions. We describe a frame-invariant formalism which minimizes the dependence of the measurements on the experimental acceptance, facilitates the comparison with theoretical calculations, and probes systematic effects due to experimental biases. This formalism is a direct and generic consequence of the rotational invariance of the dilepton decay distribution and is independent of any assumptions specific to particular models of quarkonium production. The use of this improved approach, which exploits the intrinsic multidimensionality of the problem, will significantly contribute to a faster progress in our understanding of quarkonium production, especially if adopted as a common analysis framework by the LHC experiments, which will soon perform analyses of quarkonium polarization in proton-proton collisions.     

Homogeneous immunoassay for human IgG using oriented hen egg IgY immobilized on gold sol nanoparticles

Homogeneous immunoassays using (red) gold nanoparticles represent an attractive detection scheme because of the option of photometric readout. We have applied oriented immobilization of hen egg immunoglobulin Y (IgY) on gold nanoparticles when developing a homogeneous immunoassay for human IgG. In oriented immobilization, as opposed to random immobilization, the antigen binding capabilities of the antibodies are retained. It is shown that such immunoassay has significantly better sensitivity in comparison with methods based on conventional immobilization of affinity-purified antibodies. It is also shown that hen egg IgY is better suited than rabbit antibodies, because much more antibody can be immobilized on gold nanoparticles without any destabilization, probably because of the more acidic nature of these antibodies. In addition, hen egg IgY can be supplied in higher quantity and can be prepared more easily than IgG from rabbits. Bleeding and slaughtering of animals is not needed. The assay presented here has a wide detection range (30–500?ng?.mL^?1) and a limit of detection as low as 30?ng.mL^?1 of human IgG.

Quantitation of SAR97276 in mouse tissues by rapid resolution liquid chromatography‐mass spectrometry

1,12‐Bis[5‐(2‐hydroxyethyl)‐4‐methyl‐1,3‐thiazol‐3‐ium]dodecane dibromide (SAR97276, T3) is a new antimalarial drug, which is currently being evaluated in clinical trials for severe malaria. Drug accumulation inside the parasite and a dual mechanism of action are a major strength of this compound, as it could help delay the development of resistance. The purpose of this article was to develop a rapid resolution LC‐MS method for quantifying SAR97276 in mouse tissues. The LC system consisted of Zorbax Eclipse XDB C8 (1.8 μm, 50×4.6 mm, 60°C) column. Elution with a gradient mobile phase consisting of ACN–trimethylamine‐formate buffer (pH 3) at a flow rate of 1 mL/min yielded sharp, utmost‐resolved peaks within 2 min. Tissue samples were powdered under liquid nitrogen. After protein precipitation with citric acid, SPE using WCX cartridges was used for sample preparation. There was no influence of the matrix on the detection of either SAR97276 or the IS. Assay precision was <13% and accuracy was 90–107%. The lower LOQs were 3.3 μg/kg in brain and 33 μg/kg in liver and heart. This newly developed method was used to study the tissue distribution of SAR97276 in mouse as part of the ongoing development of SAR97276.     

Multi-operator scaling random fields

In this paper, we define and study a new class of random fields called harmonizable multi-operator scaling stable random fields. These fields satisfy a local asymptotic operator scaling property which generalizes both the local asymptotic self-similarity property and the operator scaling property. Actually, they locally look like operator scaling random fields, whose order is allowed to vary along the sample paths. We also give an upper bound of their modulus of continuity. Their pointwise Hölder exponents may also vary with the position x and their anisotropic behavior is driven by a matrix which may also depend on x.     

Understanding the interactions between artemisinin and cyclodextrins: spectroscopic studies and molecular modeling

Artemisinin extracted from Artemisia annua L. proved to be currently, with its derivatives, the most effective drugs against simple and severe malaria, and is also effective on the chloroquine-resistant forms. The advantageous effect of some cyclodextrins (CDs) on artemisinin solubilization was demonstrated by different authors. The present work aims to confirm the effect of several CDs on artemisinin solubilization and to analyse the complexes formed between these CDs and artemisinin in order to understand their solubilization capacities. In this context, solubility studies, liquid-state NMR spectroscopy (¹H NMR studies and ROESY experiments) as well as theoretical studies (molecular modeling) have been performed. Randomly methylated-βCD, Crysmeb^? and hydroxypropylated-γCD were also found to improve the aqueous solubilization of artemisinin as well as βCD, γCD and hydroxypropylated-βCD whose effects were already demonstrated. The best solubilization ability was found with Crysmeb^?. The spectroscopic studies showed a lot of interactions between artemisinin and all the CDs studied, but mainly outside the cavity. Molecular modeling confirmed that artemisinin and CDs formed non-inclusion complexes.