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- Author or Editor: I. Novák x
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Abstract
Inclusion complexes of Lippia sidoides essential oil and β-cyclodextrin were obtained by slurry method and its solid powdered form was prepared using spray drying. The influence of the spray drying, as well as the different essential oil:β-cyclodextrin ratio on the characteristics of the final product was investigated. With regard to the total oil retention 1:10 mass/mass ratio as optimal was found between the essential oil and β-cyclodextrin. Thermoanalytical techniques (TG, EGD, TG-MS) were used to support the formation of inclusion complex and to examine their physicochemical properties after accelerated storage conditions. It may be assumed that the thermal properties of the complexes were influenced not only by the different essential oil/ β-cyclodextrin ratio but also by the storage conditions. In the aspect of their thermal stabilities, complex prepared with 1:10 m/m ratio (essential oil:β-cyclodextrin) was the most stable one.
In the case of a widely used spice — Origanum vulgare subsp. hirtum — the effect of different drying methods (natural, and by using dryers at temperatures of 30°C, 40 °C, 45°C) was investigated referring to the essential oil amount and composition in the final material. The sensory characteristics of olive oils flavoured by the oregano samples were also determined. The essential oil amount and the area percentage of its main component — carvacrol — were significantly influenced by the different drying temperatures. Compared to the natural way of drying in the case of the essential oil content the drying temperature of 40°C and 45°C was preferable for the higher amounts. Referring to the carvacrol area percentage the drying temperature of 30°C resulted in the highest amounts (89.74±0.28%), that was affirmed by the sensory analysis as well; based on the taste descriptions the consumers found it the most pungent one. According to our results sensory analysis data in most of the cases corresponds to the GC-MS measurements and give a much more complex characterisation of a spice.
Abstract
The extents of the protective effects of coating films on the surface of crystals were determined. Three different samples were made with different quantities of coating fluid (Sepifilm LP 010 in 10% aqueous solution). Since the atomizing rate was constant, the coating time increased in parallel with the volume of coating fluid applied. The direct measurement of film thickness and smoothness is very difficult, and therefore indirect methods were used. Dimenhydrinate was chosen as model drug; this is a heat-sensitive antihistamine with a low melting point. This temperature can be reached during the tableting process. The behaviour of samples on exposure to heat was examined by differential scanning calorimetry. The water uptakes of the samples were determined with an Enslin apparatus. Plasticity was studied with an instrumented tablet machine. These indirect methods (thermal conductivity, water uptake and plasticity measurements) revealed connections between the results of the various experiments. An overlong coating time decreased the protective effect of the coating film.
Abstract
Dimenhydrinate is a heat-sensitive antihistamine with a low melting point. The heat-sensitive feature is of importance if direct compression is used. Direct measurement of the heat originating in the texture of tablets during compression is very difficult. Thermoanalytical methods were used as indirect methods to describe the changes in material properties at high temperature: differential scanning calorimetry, thermomicroscopy and thermogravimetric analysis. Film coating method is widely used in pharmaceutical technology. A fluidized bed apparatus was applied to coat the crystals. The coating film forming agent was hydroxy-propyl-methylcellulose (HPMC), which is a gastric-soluble polymer. Thermoanalytical measurements reveal that dimenhydrinate crystals are sensitive to heat. Film coating method does not alter the shape of the DSC curve of dimenhydrinate, but increases the melting point. The presence of a macromolecular film reduces the thermal conductivity, because it separates the particles.
Abstract
The biodiesel obtained by transesterification by reaction between ester and an alcohol in the presence of catalyst. The purpose of this work is to evaluate the thermal and kinetic behavior of the methanol biodiesel derived from cotton oil. The quality analysis was done by gas chromatography and proton nuclear magnetic resonance spectrometry (1H NMR) in order to examine if the product meets with the requirements of the European Standard EN 1403. The thermogravimetric profile of the cotton biodiesel indicated that the decomposition steps are associated to the volatilization and/or decomposition of the methyl esters. Kinetic data was also obtained by thermal analysis.
Abstract
We determined 35 major, minor and trace elements in sandstone samples taken from building blocks of 19 Angkor temples and from an old and a new quarry using INAA. We also characterized the sandstone samples with conventional microscopy and electron microprobe analysis. Using cluster analysis, we found no straightforward correlation between the chemical/petrological properties of the sandstones and a presumed period of individual temples construction. The poor correlation may result either from the inherent inhomogeneity of sandstone or just reflect the diversity of quarries that supplied building blocks for the construction of any particular temple.
The chemotaxis of human peripheral phagocytes, neutrophils and monocytes was examined in a strong static magnetic field (0.317±0.012 Tesla). The chemotaxis of the suspension of purified neutrophils and monocytes was tested in the Boyden chamber using C5a as a chemotactic signal. The chambers were placed into a temperature regulated (36.6 °C) equipment producing a strong static magnetic field (0.317 Tesla) for 60 minutes. The movement of cells proceeded into a nitrocellulose membrane toward the north-pole of the magnet, i.e. in the direction of the Earth's gravitational pull. The C5a induced chemotaxis of human neutrophils decreased significantly in the strong static magnetic field. Monocytes were not significantly effected. The strong static magnetic field decreased the chemotactic movement of neutrophils and this phenomenon may have implications when humans are exposed to magnetic resonance imaging for extended periods of time.
The paper describes research in geomagnetism and aeronomy carried out in the framework of a project organized by the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences. It includes the development of the instrumentation of the Nagycenk Geophysical Observatory (geomagnetic measuring systems, ionosonde), moreover other instrumental and methodological developments, too. Observatory data are available in a database. Based on results of the Nagycenk and Tihany observatories and on data of permanent and temporal networks, long-term trends of different electromagnetic parameters were investigated. Thus geomagnetic activity was found secularly increasing, a decrease of the atmospheric electric potential gradient and a 11-year modulation of the winter/December attenuation of the geomagnetic pulsation activity were confirmed. Several possibilities (pulsations, whistlers, modelling) were used to improve knowledge about structure and parameters of the magnetosphere. Electromagnetic precursors of earthquakes were looked for. A significant increase of understanding was obtained in connection with Schumann resonances and electromagnetic transients caused by lightning. It was shown that see-coasts influence characteristically changes in ionospheric trends ( h m F2). When looking for the effect of the global climate changes in the subsurface electric resistivity, an example was discovered for the decrease of the resistivity due to infiltrating water from precipitation. Electromagnetic exploration of tectonically conditioned weak zones was continued, too.
