Inductively coupled plasma mass spectrometry (ICP-MS) is a popular method for the analysis of waters with various matrices and salinity. One of the difficulties of routine measurements by ICP-MS is spectral interferences conditioned by polyatomic ion formation in the plasma. The detection of the background concentration of such elements as vanadium, chromium and arsenic in natural waters by ICP-MS is complicated because of the polyatomic interferences, having the same mass-to-charge ratio. Thus, the purpose of this article is to determine the optimal rate of helium flow for the effective correction of polyatomic interferences of vanadium, chromium and arsenic and the reduction of their detection limits in Cl-rich waters. This research has been carried out using an inductively coupled plasma mass spectrometer NexION 300D with a universal cell technology (UCT) (PerkinElmer, USA) and three model solutions. For the detection of vanadium, chromium and arsenic content in chloride matrix water by ICP-MS, a collision mode is preferable for polyatomic interference correction. The optimal helium flow rate for this purpose is 2.5 ml/min. Under these conditions, the detection limit of vanadium, chromium and arsenic decreases by order of two

The study of silicon species in organic-rich waters is a very significant problem. This type of waters is widely spread all over the world. It is characterized by a high content of humic substances, high color of water and low pH. In this regard, a certain determination of silicon concentration in this type of waters is impossible without a preliminary investigation of silicon species. The aim of this research is therefore an investigation of the ratio of silicon dissolved forms in organic-rich waters depending on the silicon concentration and the acidity of the water. The study of pH influence on silicic acids and a silicon-humic matter interaction was carried out using model solutions and natural bog waters (Tomsk region). It has been found that the degree of polymerization of silicic acids essentially depends on the acidity of a solution. Scanning of spectrophotometric measurements has shown that silicon does not form stable complexes with fulvic and humic acids in weak-acid media (рН 3-4). Studying the bog waters of Tomsk Region has shown that they (рН=3.66-3.80) contain only monomeric-dimeric and polymeric forms of silicic acids

In recent years, the number of students with learning difficulties has increased. Often, children with a high level of intellectual development cannot cope with the primary school program. The success of studying at school is largely determined by the level of development of the executive function. There is evidence that the results of sensorimotor tests coincide with the results of the evaluation of executive function. The purpose of the study: to find a connection between the results of sensorimotor tests and the academic performance of elementary school students. The study involved 108 children aged 9-11 years. Annual marks in all subjects for grades 2 and 3 were taken into account. The diagnostic unit consisted of 7 hardware and software tests that evaluated various parameters of simple and complex sensorimotor reactions. Results. Factorial and regression analysis of the data were carried out, statistically significant relationships between academic performance and indicators of complex sensorimotor tests were revealed. The tests included three main elements of executive function: inhibitory control, working memory and cognitive flexibility. The results of certain sensorimotor tests predict academic performance in grades 2 and 3. Apparently, this is due to the fact that the tests simulate the learning process in real conditions when it is necessary to show cognitive flexibility. The relationship of academic performance with simple sensorimotor reactions has not been revealed. Conclusion. The use of certain sensorimotor tests for older preschoolers and first grade students will allow identifying children at risk of learning difficulties before these difficulties arise and have a negative impact on the development of the child's personality. The use of software and hardware complexes for conducting sensorimotor tests makes it possible to examine large groups of children in a short time, which is convenient in educational institutions. The results of testing of younger schoolchildren will help to develop an optimal educational route for each child, taking into account the peculiarities of the functioning of the nervous system.

The relevance of the study is determined by the increasing number of younger schoolchildren with difficulties in mastering reading and writing. In recent decades, the hypothesis has been confirmed that one of the causes of difficulties in mastering reading and writing in elementary school may be reduced sensory reactivity of the vestibular system. The article presents the results of an experimental study of dynamic visual acuity in children with learning difficulties. Dynamic visual acuity reflects the quality of interaction between the visual and vestibular systems. Its violations can complicate the development of reading and writing. The study involved 35 primary school students with learning difficulties. The study was conducted on the basis of a pediatric neurological clinic, instrumental studies and vestibular training were conducted as prescribed by a neurologist. At the first stage, functional diagnostics of vestibular function was carried out. The functions of the otolith part of the vestibular apparatus were evaluated by the method of cervical vestibular evoked potentials. The functions of the horizontal semicircular channels of the vestibular apparatus were evaluated by measuring the duration of post-rotational nystagmus. The experimental group included children whose learning difficulties were combined with sensory hyperactivity of the vestibular system or asymmetry of sensory reactivity of the vestibular system. Then the children underwent vestibular training on a riding simulator with visual biofeedback. The duration of the training is 14 days. The assessment of dynamic visual acuity was carried out by the standard method in sitting and standing positions before and after the training. Dynamic visual acuity depends on the quality of the vestibulocular reflex. It is shown that vestibular training on a riding simulator with visual biofeedback significantly improves dynamic visual acuity in a group of children with hyperactivity, symptoms of astheno-neurotic syndrome, asymmetry of sensory reactivity of the vestibular apparatus. Further research is needed to assess the impact of the training results on the success of children in learning.