Solid solutions of Co1−xZnxFe2O4 and Ni1−xZnxFe2O4 (0 < x < 1) nanoparticles were synthesized by sol-gel self-propagating combustion method. The obtained single cubic phase product has a specific surface area 25 m2∙g−1 to 33 m2∙g−1 and crystallite size 25 nm to 40 nm. Lattice parameters change linearly from 8.371 A (CoFe2O4) and 8.337 A (NiFe2O4) to 8.431 A (ZnFe2O4). The saturation magnetization (Ms) changes non-linearly from 60.8 emu∙g−1 (CoFe2O4), respectively, from 35.6 emu∙g−1 (NiFe2O4) to 3.3 emu∙g−1 (ZnFe2O4) reaching maximal value 76.1 emu∙g−1 for Co0.8Zn0.2Fe2O4 and 64.9 emu∙g−1 – for Ni0.6Zn0.4Fe2O4.
Sarmīte Janceva, Tatjana Dižbite, Gaļina Teliševa, Laima Vēvere, Jeļena Krasiļņikova and Mārcis Dzenis
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.
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.
Ingars Reinholds, Iveta Pugajeva and Vadims Bartkevičs
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.
Olga Muter, Andrejs Bērzinš, Tūrs Selga, Ruta Švinka and Visvaldis Švinka
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.
Lauris Rupeks, Viktor Filipenkov, Ivars Knets, Visvaldis Vitins, Marina Sokolova, Liga Stipniece and Mara Pilmane
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.
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.
The aim of this study was to detect major whey proteins α-lactalbumin and β-lactoglobulin by reversed-phase high-performance liquid chromatography (RP-HPLC). RPHPLC methods were developed using the column YMC Pack-C4, which enabled the separation of whey proteins within 30 min. Mobile phase was acetonitrile/water/0.1% trifluoroacetic acid (TFA) with gradient elution, flow rate was 1.0 mL·min−1, and the detection wavelength was 210 nm. Column temperature was 40°C and injection volume was 20 μL.
Milk samples contained α-lactalbumin and total β-lactoglobulin: No. 1 - 1500 mg·L−1 and 3600 mg·L−1; No. 2 - no α-lactalbumin and 450 mg·L−1 total β-lactoglobulin; No. 3 - 800 mg·L−1 and 94 mg·L−1, respectively.
Water-soluble polymer, cationic poly(N-[3-hexyldimethyl-aminopropyl] methacrylamide bromide) (PHDAPMAA), is synthesized by radical polymerization and studied in terms of its solubility, viscosity, surface tension and conductivity. Viscometry and surface tension measurements confirmed that intramolecular hydrophobic microdomains were formed by the pendent alkyl chains. Conductivity of cationic polymer in aqueous solution was determined. Variation of conductivity versus concentration in investigated system exhibits a typical polyelectrolyte behaviour.