Determination of copper and cadmium by atomic absorption spectrometry with electrochemical and sorption preconcentration

A method is proposed for the determination of copper and cadmium by atomic absorption spectrometry in a propane-butane-air flame with electrochemical and sorption preconcentration. Electrochemical preconcentration was performed on metal (tantalum, titanium, molybdenum, and platinum), glassy-carbon, and spectrographic graphite electrodes. Sorption preconcentration was performed on filter paper with immobilized dithizone, 8-hydroxyquinoline, and rubeanic acid. It is demonstrated that copper and cadmium can be determined in water within the concentration range 1-10 μg/L

Coulometric determination of the antioxidant capacity of tea extracts using electrogenerated bromine

A coulometric procedure based on the reaction between aqueous extracts of tea with electrogenerated bromine compounds was proposed for the rapid estimation of the antioxidant capacity of different kinds of tea. The antioxidant properties of tea with respect to bromine are mainly due to naturally occurring flavonoids, tannins, and some vitamins. Photometric and coulometric data for black teas exhibit good correlation. © 2001 MAIK "Nauka/Interperiodica"

Genetic determinants of resistance to hypoxia as one of the success factors in martial arts

Objective: to study the genetic selection of the EPAS1 gene (G/А, rsl867785) in a group of athletes involved in Greco-Roman wrestling with different levels of sportsmanship. Materials and methods: the genetic examination of 79 male athletes (from 7 to 25 years old) involved in Greco-Roman wrestling and 92 controls (from 7 to 30 years old) was performed. Results: the frequency of A-allele associated with better adaptation to hypoxic conditions was higher in the group of wrestlers (EPAS1*GG - 27.8% EPAS1*AG - 67.1% and EPAS1*AA - 5.1% against EPAS1*GG - 56.5% EPAS1*AG - 35.9% and EPAS1 *AA - 7.6 %. x2 = 16.7 p = 0.0002). The frequency of A-allele carriers increased with increasing level of sportsmanship of studied athletes. The increase in the frequency of minor A-allele in the subgroup of Greco-Roman wrestlers testifies to their advantage in comparison with the carriers of G-allele. Conclusions: G/A-polymorphism of the EPAS1 gene can be used in the selection and prediction of sports success in Greco-Roman wrestling

Potentiometric determination of ascorbic acid: Estimation of its contribution to the total antioxidant capacity of plant materials

It was found that an iodine-modified platinum electrode gives a linear potentiometric response to 1.0 × 10-5 to 1.0 × 10 -3 M ascorbic acid in model solutions. Ascorbic acid in some preparations was determined by potentiometry. The contribution of ascorbic acid to the total antioxidant capacity of aqueous extracts of hips, hop cones, and lemon juice was estimated

Determination of uric acid by voltammetry and coulometric titration

Possible mechanisms of the electrochemical oxidation of uric acid at platinum, gold, graphite, and copper electrodes in a 0.5 M NaOH solution and phosphate (pH 6.86) and borate (pH 9.18) buffer solutions were considered. The stoichiometric coefficients in the reaction of boric acid with electrogenerated bromine and hypobromite ion were determined. Working conditions for the voltammetric determination of uric acid were selected and the detection limits for uric acid were found in model solutions and blood serum. © 2001 MAIK "Nauka/Interperiodica"

Determination of fat-soluble antioxidants by galvanostatic coulometry using electrogenerated oxidants

It was found that vitamin E reacts with electrogenerated chlorine and bromine, as well as with silver (I) and vanadium(V) in the ratio 1:1 to form α-tocopherylquinone. Vitamin A reacts with electrogenerated halogens in the ratio 1:3. Individual fat-soluble antioxidants were determined in model solutions at the milligram level with RSD between 1 and 4%. The bromine-scavenging antioxidant capacity of some vegetable oils and animal fats was evaluated

Use of electrogenerated bromine for estimating the total antioxidant capacity of plant raw materials and plant-based medicinal preparations

Based on the results of determining individual antioxidants, electrogenerated bromine was proposed as a regent for the coulometric determination of the antioxidant capacity of aqueous and aqueous-alcoholic extracts of 35 phytopreparations

Determination of ionol by voltammetry and coulometric titration

Procedures were developed for determining ionol by voltammetry and by coulometric titration with electrogenerated chlorine using the amperometric indication of the titration end point. Possible mechanisms of ionol oxidation with electrogenerated chlorine and its electrochemical oxidation at a glassy carbon and a gold electrode were discussed. Procedures were developed for determining ionol in mineral oil in analytical ranges from 1.0 × 10 -4 to 1.0 × 10-2 M (RSD = 9%) and from 3.0 × 10-5 to 4.0 × 10-3 M (RSD = 9%) using a glassy carbon and a gold electrode, respectively. The detection limits for ionol at the glassy carbon and gold electrode were 2.8 × 10-4 and 1.0 × 10-5 M, respectively. The detection limit in coulometric titration was 20 μg/mL

A Markovian event-based framework for stochastic spiking neural networks

In spiking neural networks, the information is conveyed by the spike times, that depend on the intrinsic dynamics of each neuron, the input they receive and on the connections between neurons. In this article we study the Markovian nature of the sequence of spike times in stochastic neural networks, and in particular the ability to deduce from a spike train the next spike time, and therefore produce a description of the network activity only based on the spike times regardless of the membrane potential process. To study this question in a rigorous manner, we introduce and study an event-based description of networks of noisy integrate-and-fire neurons, i.e. that is based on the computation of the spike times. We show that the firing times of the neurons in the networks constitute a Markov chain, whose transition probability is related to the probability distribution of the interspike interval of the neurons in the network. In the cases where the Markovian model can be developed, the transition probability is explicitly derived in such classical cases of neural networks as the linear integrate-and-fire neuron models with excitatory and inhibitory interactions, for different types of synapses, possibly featuring noisy synaptic integration, transmission delays and absolute and relative refractory period. This covers most of the cases that have been investigated in the event-based description of spiking deterministic neural networks

Influence of the transferred coronavirus infection on diseases of the endocrine system in athletes

Purpose: to study the effect of the transferred viral (on the example of COVID‑19) infection on the endocrine system of athletes.Materials and methods: the data of 1114 athletes (average age 22.23 ± 4.18 years) who underwent in‑depth medical examination in the period 2021–2022 were analyzed. The examination included an analysis of sports and infectious anamnesis, the results of hormonal, biochemical and instrumental studies.Results: coronavirus infection was suffered by the majority of athletes — 724 people (65 %) — in the vast majority of cases (91 %), their disease was asymptomatic or mild. 390 athletes (35 %) had no history of infection. There was a significant increase in the incidence of hypothyroidism, thyrotoxicosis, insulin‑dependent diabetes mellitus, autoimmune thyroiditis among athletes who had a coronavirus infection when compared with athletes who were not ill. The development of endocrine diseases did not depend on the severity of the infection and was most often detected with its mild and asymptomatic course. During the examination, six cases of newly diagnosed type 1 diabetes mellitus and eight cases of thyrotoxicosis were detected among athletes who had a coronavirus infection. The development of these conditions did not depend on the severity of the infection. At the same time, only 1 case of thyrotoxicosis was registered in athletes who were not ill, no new cases of type 1 diabetes mellitus were diagnosed. In the present study, no association was found between the transmitted coronavirus infection and an increase in the number of cases of nodular goiter, hyperprolactinemia and type 2 diabetes mellitus.Conclusion: the results of the study showed that in the long‑term period after COVID‑19, autoimmune endocrine diseases, such as primary hypothyroidism, diffuse‑toxic goiter with thyrotoxicosis, autoimmune thyroiditis, type 1 diabetes mellitus, were significantly more often manifested in athletes, which is probably associated with a cross‑lesion of autoimmunity against a background of viral infection