The influence of solvent, storage time and temperature on the stability of the mycotoxin sterigmatocystin (STC) was investigated. STC calibrants (1.0 μg mlE-1) in acetonitrile, methanol and mixture of acetonitrile and methanol (50:50, volume/volume) were stored in dark glass bottles at (– 25), 4 and 25 °C for up to 8 weeks. Samples were analysed by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Obtained results indicate that more suitable solvents for storage of STC standard solutions at (–25 °C) are acetonitrile and mixture of acetonitrile and methanol (50:50, v/v), but not longer than for one week; for storage at 4 °C more suitable is mix of acetonitrile and methanol, but not longer than for one week.

Iodine is a mineral that is added to the table salt and found in a variety of foods. It is important for good health and, fortunately, our bodies require it in minute quantities. Iodine is part of a hormone, thyroxin, which is responsible for maintaining a person’s metabolic rate. Iodine is the basic constituent part of the hormone of the thyreoid gland. On the whole, the amount of T3 and T4 correlates with the number of the iodine atoms. Therefore, without iodine the thyreoid gland cannot synthesize hormones and, therefore, cannot function. The role of iodine intake in both of these conditions was recognized in the 20th century, and since they are fully preventable through diet, public health advocates hope to entirely eliminate them at some point. Many things are natural sources of iodine. Saltwater fish and sea vegetables, for example, both contain abundant amounts of iodine. The material can also be found in plants grown on soil which is rich in sea materials, and in animals grazed on such soils. In some regions of Latvia, however, access to iodine is limited, and conditions like goiter, is realistic of iodine deficiency situations. In Latvia, some fear exists for manufacturers of food who use iodized salt. They are afraid that it will collide with changes of colour or taste of their products and will infringe on interests of the consumer. The main question for such problems is: is it a myth or the truth? In Latvia, starting using iodine salt in manufacturing, the most important question is: ‘What quantity of iodine remains after the technological processing?‘

Thermal wood modification has been intensively studied in the recent decades because of the possibility to produce wood with improved biodurability and dimensional stability without use of harmful chemicals. Beside altered physical characteristics, wood colour is changed to lighter or darker brown as a result of thermal treatment. Growth of interest in thermal wood treatment has stimulated numerous researches concerned with discoloration of thermally modified wood which is subjected to light exposure. The objective of this study was to evaluate the colour stability of thermally modified hardwood during storage in the dark where wood discolouration is not photoinduced but rather a result of oxidative ageing. Three thermally modified hardwood species – aspen (Populus tremula L.), alder (Alnus incana Moench), birch (Betula pendula Roth.), where investigated. Wood discoloration was monitored by spectrophotometrical measurements of reflectance spectra and chromaticity parameter calculations using CIELAB colour system where L* is the lightness, and a* and b* are the chromatic coordinates. The colour stability of thermally modified wood as well as of untreated wood of the same species was examined by means of assessment of the colour parameter changes (ΔL*, Δa*, Δb*, ΔEab). All wood specimens under study discoloured during the experiment, but the colour change did not exceed two units that are common and accepted for wood products. Untreated and thermally modified wood showed different trends of discoloration during storage in the dark. The final colour changes that were fixed at the end of the experiment were greater for the thermally treated wood.

The article presents the natural and regulated stream bed stability and self-regulation issues. River beds equilibrium patterns are defined by Lane principle, observed in natural beds, while this balance is disturbed in regulated ones which has been confirmed by research. Natural and regulated rivers stability was evaluated by beds hydrodynamic stability criteria. It showed that the investigated natural rivers bed is stable enough. Under accumulated silt particle sizes in natural river beds, the formation regularities of meanders were determined. The investigated river meanders patterns confirmed the formation of natural river meanders characterizing patterns. It was found that regulated Lithuanian streams through self-beds meandering are useful not only for the natural diversity formation, but also increase meandering bed sediments conveyance capacity and stability from 3 to 3.5 times. Adapting to these naturally occurring processes and using the extensive channel maintenance techniques, it is possible to force the disruption of regulated streams hydrodynamic equilibrium self-recovery and biodiversity. The aim of research - according to the selected river bed hydrodynamic stability criteria to perform comparative analysis of stability of regulated and natural streams.