Physicochemical Properties of Zwitterionic Drugs in Therapy

In solution, amphoteric compounds exist in anionic, uncharged, zwitterionic and cationic forms. The importance of zwitterionic drugs is currently under-represented in the literature. Herein, the acid-base parameters, lipophilicity and solubility of such compounds are discussed to deepen the molecular-level understanding of their pharmacokinetic and pharmacodynamic behaviour. Our recent studies show there are many drug molecules, including thyroid hormones and 5-hydroxytryptophan, the precursor of the neurotransmitter serotonin, for which the contribution of the zwitterionic microspecies to the overall lipophilicity exceeds that of the uncharged one, which is of higher individual lipophilicity, but occurs in much lower concentration. The second part of the minireview highlights the most important zwitterionic compounds in therapy, grouped into therapeutic classes. The importance of the charge of the molecules is emphasized in their binding to the target molecules.     

Determining adulteration of canned products using SNIF-NMR and IRMS: detection of undeclared addition of synthetic acetic acid

Possible adulteration of canned products containing spirit vinegar pickle by adding synthetic acetic acid is a significant problem of the food industry. Isotope analyses, which determine botanical origin of acetic acid and also can detect synthetic acid, were applied to detect undeclared addition of synthetic acetic acid to canned products. The aim of the study was to improve the extraction technique for the SNIF-NMR (²H/¹H; site-specific natural isotopic fractionation-nuclear magnetic resonance) and IRMS (¹³C/¹²C; isotope ratio mass spectrometry) isotope methods and for an atypical matrix and to determine isotope ratios in canned vegetables pickle to prove their adulteration or authenticity. The following set of canned products was analysed: pickled cucumbers (n = 16) and one vinegar pickle purchased in the Czech market and six model (cucumber) pickles. The determined ratios of ²H/¹H and ¹³C/¹²C for the pickled cucumbers proved to be authentic ranged from 89.4 to 107.0 ppm and from ?28.7 to ?15.6 ‰, respectively; for the synthetic acetic acids diluted with water they ranged from 114.2 to 129.0 ppm and from ?44.9 to ?33.4 ‰, respectively. Isotope analyses were confirmed as a reliable tool for assessing authenticity of canned products. The method enables detection of synthetic acetic acid addition into vinegars and canned vegetables containing vinegar pickle up from 20 % (of total acidity).     

Coastal environment: EC‐cost 48 bioconversion projects and economic aspects

Seaweed has proved to be both a potential resource and a problem for coastal areas. In the framework of the European Communities, a scientific commission was created some 8 years ago, in order to address the matter of seaweed bioconversion in Europe. A book, recently published, represents a fair review and survey of seaweed as a resource in Europe. The matter of seaweed problems and expanded use is now under study in a new programme.

This paper traces back the development and growth of this inter‐European effort and also provides an overview of achievements.     

Gas diffusion electrodes for high temperature PEM-type fuel cells: role of a polymer binder and method of the catalyst layer deposition

The topic of this study is the optimization of the preparation procedure and chemical composition of a gas diffusion electrode (GDE) for utilization in high-temperature PEM fuel cells. A phosphoric acid-doped polybenzimidazole derivative membrane was used as a polymer electrolyte. The following parameters were studied: nature and content of the polymeric binder (PTFE—hydrophobic, PBI—hydrophilic) in the catalytic layer (CL) and concentration of platinum in catalytic powder (affecting the thickness of the CL). Brushing and spraying were selected as the most suitable techniques of CL deposition. Surprisingly, both polymeric binders investigated in the framework of this study were found to provide a similar GDE performance for CL deposited on the gas diffusion layer surface by spraying.     

Porous scaffold prepared from α′L-Dicalcium silicate doped with phosphorus for bone grafts

α′_L-Dicalcium silicate ceramic doped with phosphorus in subsystem Ca₂SiO₄?7CaO·P₂O₅·2SiO₂ was used as a template to prepare a porous scaffold by the burnout technique using cellulose as porogen. A phase composition study of the ceramics prepared after porogen removal was performed by XRD and SEM-WDS in contrast to the base material. An analysis of the inter- and intraparticle pores network was run by mercury porosimetry. Density was measured by helium pycnometry. The scaffold's porosity was measured using Archimedes’ method by immersion in mercury. The in vitro behavior in SBF of the monophasic scaffold was analyzed by SEM-WDS, FTIR-ATR and TEM for several time periods. The processing technique allowed scaffolds to be easily and cheaply obtained with porosities of up to 81% by combining macro- and microporosity. The specific area effectively increased which, together with the good bioactivity rate obtained, make this material a promising candidate for bone grafts in tissue engineering.     

Extending OCL for OLAP querying on conceptual multidimensional models of data warehouses

The development of data warehouses begins with the definition of multidimensional models at the conceptual level in order to structure data, which will facilitate decision makers with an easier data analysis. Current proposals for conceptual multidimensional modelling focus on the design of static data warehouse structures, but few approaches model the queries which the data warehouse should support by means of OLAP (on-line analytical processing) tools. OLAP queries are, therefore, only defined once the rest of the data warehouse has been implemented, which prevents designers from verifying from the very beginning of the development whether the decision maker will be able to obtain the required information from the data warehouse. This article presents a solution to this drawback consisting of an extension to the object constraint language (OCL), which has been developed to include a set of predefined OLAP operators. These operators can be used to define platform-independent OLAP queries as a part of the specification of the data warehouse conceptual multidimensional model. Furthermore, OLAP tools require the implementation of queries to assure performance optimisations based on pre-aggregation. It is interesting to note that the OLAP queries defined by our approach can be automatically implemented in the rest of the data warehouse, in a coherent and integrated manner. This implementation is supported by a code-generation architecture aligned with model-driven technologies, in particular the MDA (model-driven architecture) proposal. Finally, our proposal has been validated by means of a set of sample data sets from a well-known case study.     

Contribution to Modeling of Hydrogen Effect on Oxygen Diffusion in Zy-4 Alloy During High Temperature Steam Oxidation

Previous studies have shown that the numerical model EKINOX-Zr was able to simulate with accuracy oxide growth and oxygen diffusion into the matrix during high-temperature oxidation of Zy-4. In this study, the aim of the development was to evaluate if the observed effect of hydrogen cladding content on the increase of oxygen solubility in the high-temperature β_Zr was only a thermodynamic effect. Previous experimental studies have shown that hydrogen induces an evolution of equilibrium oxygen concentration at the α_Zr/β_Zr interface. The present work showed that EKINOX-Zr linked with the thermodynamic database Zircobase reproduced the evolution induced by hydrogen during the high-temperature steam oxidation. However, the results showed also that additional studies are necessary to better understand hydrogen behavior during high-temperature oxidation of Zr.