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Open access

Jūlija Karasa and Ksenija Ivanova

Abstract

Raw clays from the Baltic region are characterized as smectite containing clays with significant amount of naturally occurring impurities that limiting the potential applications of crude Baltic clay resources. Purification of clay samples from Šaltiškių deposit (Venta basin) was carried out by varied concentration hydrochloric acid solutions and resulted in fine removal of carbonates and iron oxide. The main idea of this work is to widen the possible applications of local clay resources providing a new type of raw material for further organoclay production.

Open access

Lauris Rupeks, Viktor Filipenkov, Ivars Knets, Visvaldis Vitins, Marina Sokolova, Liga Stipniece and Mara Pilmane

Abstract

Hydroxyapatite is used for bone reconstruction, in order to improve its mechanical properties different substances can be added. In our study new biomaterial is created from deproteinised hydroxyaptite and endodentic cement, its mechanical properties were tested. Material was implanted subcutaneous in rats, then histological and biocompatability tests were performed. Results indicate that stuff has good mechanical properties, short setting time and gradual resorption creating porosity and ability to integrate in bone.

Open access

Olga Muter, Andrejs Bērzinš, Tūrs Selga, Ruta Švinka and Visvaldis Švinka

Abstract

Ceramic granules fabricated from Quaternary clay at 1200°C were tested for their flotation ability in a water model system containing silicone oil. The presence of oil in the liquid phase improved flotation of granules, probably due to sorption of oil by ceramics. Coating of granules with SiO2 resulted in decreased flotation ability, irrespectively of the presence of oil. Granules were shown to be appropriate for bacterial colonization.

Open access

Ingars Reinholds, Iveta Pugajeva and Vadims Bartkevičs

Abstract

This research demonstrates the development of reliable multi-component methods for the detection of antibiotic residues in environmental biota. The efficiency of analytical performance of ultra high performance liquid chromatography (UHPLC) techniques with triple quadrupole (QqQ-MS/MS) and Orbitrap high-resolution mass spectrometry (Orbitrap-HRMS) detectors is discussed. Antibiotic residues in biota samples collected in Latvia were analysed. The contamination status was determined as rather low within acceptable levels set by the European Union Regulations.

Open access

Eduards Dokukins and Olga Muter

Abstract

The effect of liquid paraffin and diesel oil as nutrient amendments for hydrocarbon-degrading bacteria was compared. Different parameters were analyzed - optical density of bacterial suspension, oxygen consumption by biomass, morphology of bacteria, etc. In some experiments the paraffin was more preferable for microorganisms, but in other tests the results for both substances were similar. The influence of the comparable substances strongly depends on cultivation conditions.

Open access

Sarmīte Janceva, Tatjana Dižbite, Gaļina Teliševa, Laima Vēvere, Jeļena Krasiļņikova and Mārcis Dzenis

Abstract

With the purpose to assess potential of alder tree bark as a renewable source of bioactive polyphenolic compounds, antioxidant properties of hydrophilic extracts and proanthocyanidins (PAC) isolated from bark of two alder species (grey alder and black alder) growing in Latvia have been examined employing two test systems, ABTS●+, DPPH assays. In the tests the high free radical scavenging capacities of the PAC were demonstrated. The polyphenolic nature of the bark PAC opens the possibility of its application as food additive. The PAC has good potential as an antioxidant for mayonnaise.

Open access

Gaida Sedmale, Martins Randers, Liga Grase and Juris Kostjukovs

Abstract

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.

Open access

Dagnija Vecstaudza, Maris Klavins, Olga Muter and Reinis Rutkis

Abstract

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.

Open access

Laura Klavina and Jorens Kviesis

Abstract

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.