There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

https://link.springer.com/content/pdf/10.1007%2Fs11538-016-0214-9.pdf

Mathematical Models for Immunology: Current State of the Art and Future Research Directions.

INTRODUCTION Single Stressor Studies Multiple Stressor Studies Types of Combination Effects Examples of Combination Effects

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Effects of Toxic Stimuli Combinations on Determination of Exposure Limits

Determination of food toxic compounds is one of the significant strategies for investigating food quality. The presence research introduces an electrochemical approach for toxic ractopamine sensing using a gold electrode amplified with gold nanoparticles (Au-Nps/AuME). The oxidation signal of ractopamine was investigated at the surface of Au-Nps/AuME, and results showed a 2.36-fold amplification in current and reducing 100 mV in oxidation potential compare to the pristine gold electrode. The redox reaction of ractopamine shows a pH dependence behavior with two electrons and two protons. Furthermore, the scan rate and chronoamperometric investigation showed a diffusion coefficient of 1.0 × 10−6 cm2/s to the oxidation reaction of ractopamine at the surface of Au-Nps/AuME. Analytical investigation showed a linear dynamic range of 0.1–380 µM for sensing of ractopamine using square wave voltammetric technique. Also, Au-Nps/AuME could be used to measure ractopamine in food samples such as pork samples with a recovery range of 98.3–103.9% and a detection limit of 50 nM.

An electrochemical strategy for toxic ractopamine sensing in pork samples; twofold amplified nano-based structure analytical tool

Strontium enhances osteogenic differentiation of mesenchymal stem cells and in vivo bone formation by activating Wnt/catenin signaling

Introduction. The element composition of urine is relevant and demanded index in biomedical, biomonitoring studies to assess the level of contamination of biological media and public health risks. Material and methods. The content of 12 elements (V, Cr, Mn, Ni, Cu, Zn, As, Se, Sr, Cd, Tl, Pb) in urine of unexposed children (n = 100 and n = 57, respectively, average age < 6 years) residing in the rural and industrial region of the Western Urals was determined by ICP-MS using Agilent 7500cx inductively coupled plasma quadrupole mass spectrometer (Agilent Technologies, USA) with an octopole reaction / collision cell (ORS). The measurement was carried out according to Methodical Guidelines 4.1. 3230-14 (FR.1.31.2014.17064) developed by the authors. Urine samples were directly analyzed after 1/10 dilution (V / V) with 1% nitric acid solution. The validity of the results was confirmed by analysis of standard urine samples SERONORMTM urine (Norway). The results were presented as basic statistical indices: minimum and maximum values, arithmetic mean (AM), geometric mean (GM), 5th, 50th, 95th percentiles, and were interpreted in accordance with current international requirements. Results. In the unexposed group of children the arithmetic mean (AM) for vanadium is 0.68 μ/l; chromium - 1.91 μg/l; manganese 0.96 - μg/l; nickel - 1.84 μg/l; copper - 13.28 μg/l; zinc - 270.56 μg/l; arsenic - 18.- 99 μg/l; selenium - 22.55 μg/l; strontium - 239.09 μg/l; cadmium - 0.12 μg/l; thallium - 0.16 μg/l; lead - 0.83 μg/l. The arithmetic mean in the group of children of the industrial territory for vanadium is - 0.72 μg/l; chromium - 2.13 μg/l; manganese - 1.11 μg/l; nickel - 2.76 μg/l; copper - 26.67 μg/l; zinc - 482.1 μg/l; arsenic - 10.09 μg/l; selenium - 32.84 μg/l; strontium - 1275.35 μg/l; cadmium - 0.122 μg/l; thallium - 0.16 μg/l; lead - 2.16 μg/l. Evaluation of the results of the study showed AM excess of nickel, copper, zinc, strontium and lead. Conclusion. The paper presents regional features of the urine elemental composition in children who permanently reside in Western Urals’ rural and industrial areas. The study results based on the 95 percentile (P95) can be used as approximate reference data as a basis for assessing the risk associated with exposure to metals. The comparative evaluation of the obtained results with the reference concentrations used in Europe, the USA and Canada for national human biomonitoring programs was carried out.

Assessment of the content of toxic and essential elements in the urine of children residing in rural and industrial regions in Western Urals

A sequencing of the candidate genes of the pupils, exposed to strontium by the method of targeted resequencing has been performed. It is shown, that under conditions of increased revenues of strontium in drinking water the number of polymorphonuclear altered portions of candidate genes increases. As a result of the targeted resequencing in conditions of strontium exposure, the maximum polymorph modifications of the following genes are defined: sulfotransferase 1A1 (SULT1A1) and methylenetetrahydrofolate. It was shown that the structure of the mutations in conditions of the strontium exposure was characterized by the formation of defects in the gene mapping detoxification (38.5 % of all mutations) and immunoregulation (22.5 %). Analysis of the cause-effect relationships in the system \"factor the number of mutations\" revealed that candidate genes reflecting strontium exposure conditions (content of strontium in drinking water is 1.3 MAC), are genes: cytochrome P450, glutathione transaminase (detoxification); dopamine (CNS), interleukin 17 and the major histocompatibility complex (immune system), methylene-tetra-hydro-folate-reductase (reproduction).

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Polymorphism’s assessment of children’s candidate genes associated with low-level long-term exposure to strontium in drinking water

This paper focuses on improvements made into a multiphase flow model in the antroduodenum, which was developed previously. The first phase is a multi-component liquid with components (enzymes and nutrients) dissolved at the molecular level. Food particles of different sizes were assumed as separate liquid phases. In this paper we considered the neurohumoral regulation of the digestive processes in the antroduodenal part of the digestive tract. New hormonal elements of the model were introduced: gastrin, somatostatin, motilin, secretin, and cholecystokinin. Also, the influence exerted by the central and enteric nervous systems was taken into account. Within the framework of conceptual statement of the problem we proposed a system of interrelations between components in the multiphase media and neurohumoral elements. The mathematical statement of the problem includes the mass and momentum conservation equations for phases and components, ordinary differential equations for the dynamic change in the regulation elements, and moving boundary conditions. One of the main challenges is to identify numerous parameters of the developed model. At this moment we have identified parameters which describe the rates of enzymes reactions and intensity of mass sources due to components secretion. In some scenarios of computational simulation we analyzed the influence exerted by neurohumoral disorders on the flow characteristics.

A mathematical model for multiphase flow in the antroduodenum with the consideration of the neurohumoral regulation

Hygienic standards for chemical admixtures contents in food products in the Eurasian Economic Union countries are an integral part of the technical regulations adopted in the Customs Union and the EEU. However, not all of them have been substantiated by the moment in relation to acceptable consumers’ health risk. The aim of this research is to discuss fundamentals for fixing acceptable daily intake (ADI) for chemical substances in food according to human health risk criteria. We analyzed problems related to fixing hygienic standards for chemical substances in food advisable in the process to apply data obtained in previous research and published in relevant literature sources. When choosing points of the establishment for fixing ADI or provisional tolerable intake (PTI) in a situation when data on several different starting points are available, one should choose such parameters that require the application of fewer modifying factors, namely reference levels (BMD) detected as for epidemiologic research results for the most sensitive population groups. It is advisable to supplement a set of mathematic modeling techniques applied for fixing hygienic standards for chemical admixtures content in food products with evolution modeling of health risk that can be applied to verify suggested values. When fixing ADI, one should primarily apply such modifying factors as those that allow for interspecies extrapolation, points of establishment for ADI/PTI, and extrapolation of research results under short-term exposure onto persistent exposure scenarios. The suggested recommendations for substantiation of modifying factors will allow unifying their application to a certain extent when calculating ADI/PTI of chemicals. Before any permissible risk levels are fixed in a process of hygienic standard development, it is advisable to apply the following permissible health risk level: for quantitative assessment, lifelong risk of a severe disease or death being equal to 1∙10-4; for semi-quantitative risk characteristics, hazard quotient equal to 1; for risk evolution analysis, reduced health risk index equal to 0.05.

On the issue of establishing acceptable daily intake of chemical substancesin food products according to health risk criteria

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Nina V. Zaitseva

Papers

Assessment of the content of toxic and essential elements in the urine of children residing in rural and industrial regions in Western Urals

Polymorphism’s assessment of children’s candidate genes associated with low-level long-term exposure to strontium in drinking water

A mathematical model for multiphase flow in the antroduodenum with the consideration of the neurohumoral regulation

On the issue of establishing acceptable daily intake of chemical substancesin food products according to health risk criteria

Safety assessment of the maximum permitted levels of L. monocytogenes in food according to health risk criteria