Swelling of Polyheteroarylenes in Supercritical Carbon Dioxide

Two series of polyheteroarylenes have been investigated with regard to their physical properties before and after swelling with supercritical carbon dioxide. The study of the dependence of glass transition temperature and free volume of polymers on their conformational rigidity showed that the process of swelling in supercritical carbon dioxide is influenced by the voluminous side groups and by the high boiling solvent N-methylpyrolidinone used for the preparation of the polymers which facilitates the formation of crosslinks or complexes with the macromolecular chains.     

Determination of benzyl isothiocyanate metabolites in human plasma and urine by LC-ESI-MS/MS after ingestion of nasturtium (Tropaeolum majus L.)

A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine the concentration of benzyl isothiocyanate (BITC) metabolites in human plasma and urine. In this study, the following BITC metabolites have been considered: BITC–glutathione, BITC–cysteinylglycine, BITC–cysteine, and BITC–N-acetyl-l-cysteine. The assay development included: (1) synthesis of BITC conjugates acting as reference substances; (2) sample preparation based on protein precipitation and solid-phase extraction; (3) development of a quantitative LC-MS/MS method working in the multiple-reaction monitoring mode; (4) validation of the assay; (5) investigation of the stability and the reactivity of BITC conjugates in vitro; (6) application of the method to samples from a human intervention study. The lower limits of quantification were in the range of 21–183 nM depending on analyte and matrix, whereas the average recovery rates from spiked plasma and urine were approximately 85 and 75 %, respectively. BITC conjugates were found to be not stable in alkaline buffered solutions. After consumption of nasturtium, containing 1,000 μM glucotropaeolin, the primary source of BITC, quantifiable levels of BITC–NAC, BITC–Cys, and BITC–CysGly were found in human urine samples. Maximum levels in urine were determined 4 h after the ingestion of nasturtium. With regard to the human plasma samples, all metabolites were determined including individual distributions. The work presented provides a validated LC-MS/MS method for the determination of BITC metabolites and its successful application for the analysis of samples collected in a human intervention study.

Transformation of methyl N-methyl-N-(6-substituted-5-nitro-4-pyrimidinyl)aminoacetates into 4-methylamino-5-nitrosopyrimidines and 9-methylpurin-8-ones

N-Methyl-N-(6-substituted-5-nitro-4-pyrimidinyl)aminoacetic acid methyl esters under the treatment of sodium alkoxides, depending on the nature of substituents in 6 position of the pyrimidine ring, undergo ring closure and rearrangement to give 6-substituted-4-methylamino-5-nitrosopyrimidines or 9-methylpurin-8-ones.     

Mixed-matrix membranes composed of Matrimid and mesoporous ZSM-5 nanoparticles

Mixed-matrix membranes were prepared from Matrimid^® and mesoporous ZSM-5 nanoparticles containing crystalline ZSM-5. The ideal selectivity for H₂/N₂ separation increased from 79.6 for pure Matrimid^® to 143 at 10% loading, while the selectivity of O₂/N₂ increased from 6.6 for pure Matrimid^® to 10.4 at 20% loading. The ideal H₂/CH₄ separation factor increased from 83.3 to 169 at 20% loading. The results suggest that the mesopores of the ZSM-5 material provide good contact between the nanoparticles and the polymer, since the polymer chains can penetrate into the mesopores. The micropores of ZSM-5 crystals provide size and shape selectivity.     

Minimal-Variance Hedging in Large Financial Markets: Random Fields Approach

We study a large financial market where the discounted asset prices are modeled by martingale random fields. This approach allows the treatment of both the cases of a market with a countable amount of assets and of a market with a continuum amount. We discuss conditions for these markets to be complete and we study the minimal variance hedging problem both in the case of full and partial information. An explicit representation of the minimal variance hedging portfolio is suggested. Techniques of stochastic differentiation are applied to achieve the main results. Examples of large market models with a countable number of assets are considered according to the literature and an example of market model with a continuum of assets is taken from the bond market.     

Numerical Modelling of Convection-Driven Cooling,Deformation and Fracturing of Thermo-Poroelastic Media

Transport in Porous Media - Convection-driven cooling in porous media influences thermo-poro-mechanical stresses, thereby causing deformation. These processes are strongly influenced by the...     

Green Algae as a Drug Delivery System for the Controlled Release of Antibiotics

New strategies to efficiently treat bacterial infections are crucial to circumvent the increase of resistant strains and to mitigate side effects during treatment. Skin and soft tissue infections represent one of the areas suffering the most from these resistant strains. We developed a new drug delivery system composed of the green algae, Chlamydomonas reinhardtii, which is generally recognized as safe, to target specifically skin diseases. A two-step functionalization strategy was used to chemically modify the algae with the antibiotic vancomycin. Chlamydomonas reinhardtii was found to mask vancomycin and the insertion of a photocleavable linker was used for the release of the antibiotic. This living drug carrier was evaluated in presence of Bacillus subtilis and, only upon UVA1-mediated release, growth inhibition of bacteria was observed. These results represent one of the first examples of a living organism used as a drug delivery system for the release of an antibiotic by UVA1-irradiation.