In this report the obtaining and properties of hightemperature porous ceramic materials using local carbonate clays and quartz sand resources was studied. Materials with two different porosities were obtained by using different synthesis temperatures. The test results show that these materials contain cordierite as their main crystalline phase. The porosity directly influences the compressive strength and it is greatly reduced when overall porosity increases. The CTE of obtained materials is low − about 3-10−6 1/°C.
Juris Burlakovs, Rūta Ozola, Juris Kostjukovs, Ivars Kļaviņš, Oskars Purmalis and Māris Kļaviņš
Jurassic clay rich in organic matter from western Latvia is known already from early 19th century. Jurassic clays provide an interest because of high potential for innovative use due to its clay mineral composition jointly with organic material. Properties of the Jurassic clayey deposits were studied by using various physical and chemical methods. Material gained from field was tested by modern techniques such as UV-Vis, 3D fluorescence and FTIR - spectra, which show patterns of organic compounds in the clay material. AAS analyses characterized inorganic content. PXRD studies raised discussions about the origin of kaolin, illite and smectite and interactions among these clay minerals. Obtained results show that Jurassic clays with organic matter have future potential for possible use in cosmetic industry and as a sorbent material.
A simple, fast and reproducible analytical method for fractionation of freely available bryophyte lipids was developed. Lipid fractionation was achieved by solid phase extraction using porous silica and silica derivatized with -NH2 groups and the compounds were quantified as their trimethylsilyl derivatives by gas chromatography-mass spectrometry. The suggested fractionation method allows to identify several groups of substances prospective in respect of search of new biologically active compounds in bryophytes as well as in respect of understanding of their metabolism.
Dagnija Vecstaudza, Maris Klavins, Olga Muter and Reinis Rutkis
Surface cleaning preparations pose a serious threat to the environment. Toxicity of a pre-manufactured preparation SCP-1 was tested on bacteria, algae and higher plants and was expressed as a minimal inhibitory concentration (MIC). Obtained results showed that among unicellular and more complex testorganisms MIC values differed 10-100 fold suggesting that an application of complex test-organism battery is necessary to evaluate the toxicity of SCP-1 thoroughly. MIC values were different from the critical micelle concentration; this indicates that the SCP1 mechanism of action might not involve membrane disruption and/or destabilization.
Gaida Sedmale, Martins Randers, Liga Grase and Juris Kostjukovs
Influence of chemical, mechanical and thermal treatment on structure and properties of illite and impact on development of high-temperature ceramics was investigated. The object of this study was illite from Quartenary glacio-limnic clay of state importance deposit Apriki. Treated clay fractions were subjected to X-ray diffraction, SEM and differential thermal analysis.
It was found that thermal and chemical treatment is effective. Thermally treated illite with Al(OH)3 additive was used for sintering a new dense ceramic compositions. Ceramics were characterized by bulk density, shrinkage and compressive strength 150−165 N/mm2.