A Molecular Shuttle Driven by Fullerene Radical‐Anion Recognition

We describe a electrochemically driven molecular shuttle, in which shuttling takes place by means of fullerene radical‐anion recognition that results in a very low operation potential (E_1/2=?0.580 V vs. decamethylferrocene). This has been achieved by introducing positive charges on the macrocycle, which strengthen the existing π–π interactions between the macrocycle and the electrogenerated fullerene radical anion by means of an electrostatic component. In addition, the synthesis of such a molecular shuttle has been accomplished by developing a new synthetic approach that exploits the controlled translocation of the macrocycle as a selective protecting group.     

Synthesis, structure and solvatochromic properties of some novel 5-arylazo-6-hydoxy-4-phenyl-3-cyano-2-pyridone dyes

ABSTRACT: BACKGROUND: A series of some novel arylazo pyridone dyes was synthesized from the corresponding diazonium salt and 6-hydroxy-4-phenyl-3-cyano-2-pyridone using classical reaction for the synthesis of the azo compounds. RESULTS: The structure of the dyes was confirmed by UV-vis, FT-IR, 1H NMR, 13C NMR spectroscopic technique and elemental analysis. The solvatochromic behaviour of the dyes was evaluated with respect to visible absorption properties in various solvents. CONCLUSIONS: The azo-hydrazone tautomeric equilibration is found to depend upon substituents as well as on solvents. The geometry data of the investigated dyes were obtained using DFT quantum-chemical calculations. The obtained calculational results are in very good agreement with the experimental data.     

Simultaneous quantitation of IC87114, roflumilast and its active metabolite roflumilast N‐oxide in plasma by LC‐MS/MS: application for a pharmacokinetic study

A sensitive and reliable high‐performance liquid chromatography–mass spectrometry (LC–MS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N‐oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquid–liquid extraction and separated on a reverse phase C₁₈ column (50 mm × 3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3 > 145.9, 403.1 >186.9, 419.1 > 187.0 and 271.1 > 155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.1–60 ng.mL^?1 for RFM and RFN and 6 to 2980 ng.mL^?1 for IC87114. Intra‐ and inter‐day accuracy and precision of validated method were within the acceptable limits of <15% at all concentrations. Coefficients of correlation (r²) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drug–drug interaction study in Wistar rats. Copyright © 2012 John Wiley & Sons, Ltd.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.     

Role of noise in a market model with stochastic volatility

We study a generalization of the Heston model, which consists of two coupled stochastic differential equations, one for the stock price and the other one for the volatility. We consider a cubic nonlinearity in the first equation and a correlation between the two Wiener processes, which model the two white noise sources. This model can be useful to describe the market dynamics characterized by different regimes corresponding to normal and extreme days. We analyze the effect of the noise on the statistical properties of the escape time with reference to the noise enhanced stability (NES) phenomenon, that is the noise induced enhancement of the lifetime of a metastable state. We observe NES effect in our model with stochastic volatility. We investigate the role of the correlation between the two noise sources on the NES effect.     

Localization of proteins in paint cross-sections by scanning electrochemical microscopy as an alternative immunochemical detection technique

The qualitative identification of proteinaceous substances, as well as their location within a complex paint stratigraphy, is one of the most challenging issues in the characterization of painting materials. Nevertheless, information on paint components represent a crucial task for studies concerning both the ancient painting techniques adopted and the state of conservation, being fundamental investigations for the selection of appropriate conservation actions. The present research was aimed at developing a new detection approach for the immunochemical localization of ovalbumin in paint cross-sections based on the use of scanning electrochemical microscopy (SECM). The immunochemical analyses were performed using an anti-ovalbumin primary antibody and a secondary antibody labelled with horseradish peroxidase (HRP). SECM measurements were performed in feedback mode using benzoquinone (BQ)/hydroquinone (H₂Q) redox couple. In presence of hydrogen peroxide (H₂O₂), HRP catalyzes the re-oxidation of H₂Q to BQ and the increment of BQ concentration in correspondence of the target protein was detected by SECM through the electrochemical reduction of the regenerated BQ at the microelectrode. Indeed, the localization of ovalbumin was possible thanks to a clear discrimination of SECM currents, achieved by the comparison of the measurements recorded before and after H₂O₂ administration, based on the HRP on/off approach. The method was evaluated both on samples from standard mocks-up and on a historical sample, collected from a Renaissance wood painting. The obtained results were promising, foreseeing a wider application of SECM on cultural heritage researches.     

Photostability and solubility improvement of β-cyclodextrin-included tretinoin

In this work, we investigated the influence of β-cyclodextrin on the photostability of tretinoin and compared the photo-chemical stability of tretinoin, either in methanol or complexed with β-cyclodextrin, when exposed both to UV and fluorescent light. The physico-chemical characterization of tretinoin-β-cyclodextrin complexes, prepared by the freeze-drying process, using different tretinoin:β-cyclodextrin molar ratios (1:1 and 1:3), was carried out in solution by phase solubility studies, ¹H-NMR spectroscopy, and in solid state by infrared spectroscopy (FT-IR); these analyses confirmed the existence of an inclusion compound. Solubility study results showed that tretinoin solubility was enhanced by inclusion in β-cyclodextrin as a function of increasing concentrations of β-cyclodextrin in aqueous solution at different pH values (i.e., 3.0, 5.5, and 7.0). Moreover, the complexation of the tretinoin with β-cyclodextrin effectively protected the photolabile drug and reduced the degradation of tretinoin induced by UV and fluorescent light, improving its photo-chemical stability in comparison with free drug in methanol. Indeed, dissolved tretinoin in methanol degraded very quickly and completely, while β-cyclodextrin-included tretinoin decomposition was delayed and, after 30 days under UV exposure, the percentage of remaining drug was about 20–25% (depending on the tretinoin concentration). The photodegradation of tretinoin in methanol under fluorescent light was slower: after 5 days of irradiation it reached a photostationary state and intact tretinoin remained constant (6.6%). In conclusion, the β-cyclodextrin complexation always led to a reduction of degradation, depending on the tretinoin:β-cyclodextrin molar ratio and on the drug concentration (0.2 mg/ml or 0.4 mg/ml).     

Self-adjointness of a generalized Camassa-Holm equation

It is well known that the Camassa-Holm equation possesses numerous remarkable properties characteristic for KdV type equations. In this paper we show that it shares one more property with the KdV equation. Namely, it is shown in [1] and [2] that the KdV and the modified KdV equations are self-adjoint. Starting from the generalization [3] of the Camassa-Holm equation [4], we prove that the Camassa-Holm equation is self-adjoint. This property is important, e.g. for constructing conservation laws associated with symmetries of the equation in question. Accordingly, we construct conservation laws for the generalized Camassa-Holm equation using its symmetries.     

Strain-mediated propagation of magnetic domain-walls in cubic magnetostrictive materials

Ricerche di Matematica - The role played by magnetoelastic effects on the properties exhibited by magnetic domain walls propagating along the major axis of a thin magnetostrictive nanostrip,...