Finite element method modeling to confirm the results of comprehensive optimization of the tripolar concentric ring electrode based on its finite dimensions model.

Concentric ring electrodes are noninvasive and wearable sensors for electrophysiological measurement capable of estimating the surface Laplacian (second spatial derivative of surface potential) at each electrode. Significant progress has been made toward optimization of inter-ring distances (distances between the recording surfaces of the electrode), maximizing the accuracy of the surface Laplacian estimate based on the negligible dimensions model of the electrode. However, novel finite dimensions model offers comprehensive optimization including all of the electrode parameters simultaneously by including the radius of the central disc and the widths of the concentric rings into the model.

Comprehensive Optimization of the Tripolar Concentric Ring Electrode Based on Its Finite Dimensions Model and Confirmed by Finite Element Method Modeling.

The optimization performed in this study is based on the finite dimensions model of the concentric ring electrode as opposed to the negligible dimensions model used in the past. This makes the optimization problem comprehensive, as all of the electrode parameters including, for the first time, the radius of the central disc and individual widths of concentric rings, are optimized simultaneously. The optimization criterion used is maximizing the accuracy of the surface Laplacian estimation, as the ability to estimate the Laplacian at each electrode constitutes primary biomedical significance of concentric ring electrodes.

Looking for the LOAEL or NOAEL Concentration of Nickel-Oxide Nanoparticles in a Long-Term Inhalation Exposure of Rats.

Rats were exposed to nickel oxide nano-aerosol at a concentration of 2.4 ± 0.4 µg/m in a "nose only" inhalation setup for 4 h at a time, 5 times a week, during an overall period of 2 weeks to 6 months.

Some outcomes and a hypothetical mechanism of combined lead and benzo(a)pyrene intoxication, and its alleviation with a complex of bioprotectors.

Rats were exposed 3 times a week during 6 weeks to repeated intraperitoneal injections of lead acetate solution in water (Pb) and/or benzo(а)pyrene solution in petrolatum oil (B(а)P) in various dose ratios. Towards the end of the period, the animals developed a moderate subchronic intoxication having some features characteristic of lead effects. The type of combined toxicity estimated with the help of isoboles constructed by the Response Surface Methodology was found to be varied depending on a particular effect, its level, and dose ratio.

An overview of experiments with lead-containing nanoparticles performed by the Ekaterinburg nanotoxicological research team.

Over the past few years, the Ekaterinburg (Russia) interdisciplinary nanotoxicological research team has carried out a series of investigations using different and experimental models in order to elucidate the cytotoxicity and organ-systemic and organism-level toxicity of lead-containing nanoparticles (NP) acting separately or in combinations with some other metallic NPs. The authors claim that their many-sided experience in this field is unique and that some of their important results have been obtained for the first time. This paper is an overview of the team's previous publications in different journals.

Further verification of some postulates of the combined toxicity theory: New animal experimental data on separate and joint adverse effects of lead and cadmium.

Outbred male rats were repeatedly injected intraperitoneally two-level sub-lethal doses of lead acetate and/or cadmium chloride solutions 3 times a week during 6 weeks. The animals developed explicit, even if moderate, subchronic intoxication characterized by a large number of indices, both common to both metals (including increased DNA fragmentation coefficient) and lead-specific. Special attention was paid to hemodynamic and electrocardiographic effects.

Evaluation of Bipolar, Tripolar, and Quadripolar Laplacian Estimates of Electrocardiogram via Concentric Ring Electrodes.

Surface Laplacian estimates via concentric ring electrodes (CREs) have proven to enhance spatial resolution compared to conventional disc electrodes, which is of great importance for P-wave analysis. In this study, Laplacian estimates for traditional bipolar configuration (BC), two tripolar configurations with linearly decreasing and increasing inter-ring distances (TC and TC respectively), and quadripolar configuration (QC) were obtained from cardiac recordings with pentapolar CREs placed at CMV1 and CMV2 positions. Normalized P-wave amplitude (NAP) was computed to assess the contrast to study atrial activity.

Toxic Effects of Low-Level Long-Term Inhalation Exposures of Rats to Nickel Oxide Nanoparticles.

Rats were exposed to nickel oxide nanoparticles (NiO-NP) inhalation at 0.23 ± 0.01 mg/m³ for 4 h a day 5 times a week for up to 10 months.

Solving the general inter-ring distances optimization problem for concentric ring electrodes to improve Laplacian estimation.

Background: Superiority of noninvasive tripolar concentric ring electrodes over conventional disc electrodes in accuracy of surface Laplacian estimation has been demonstrated in a range of electrophysiological measurement applications. Recently, a general approach to Laplacian estimation for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method has been proposed and used to introduce novel multipolar and variable inter-ring distances electrode configurations. While only linearly increasing and linearly decreasing inter-ring distances have been considered previously, this paper defines and solves the general inter-ring distances optimization problem for the (4n + 1)-point method.

Combined Subchronic Toxicity of Aluminum (III), Titanium (IV) and Silicon (IV) Oxide Nanoparticles and Its Alleviation with a Complex of Bioprotectors.

Stable suspensions of metal/metalloid oxide nanoparticles (MeO-NPs) obtained by laser ablation of 99.99% pure elemental aluminum, titanium or silicon under a layer of deionized water were used separately, or in three binary combinations, or in a ternary combination to induce subchronic intoxications in rats. To this end, the MeO-NPs were repeatedly injected intraperitoneally (i.

Safety of the Transcranial Focal Electrical Stimulation via Tripolar Concentric Ring Electrodes for Hippocampal CA3 Subregion Neurons in Rats.

Epilepsy is a neurological disorder that affects approximately one percent of the world population. Noninvasive electrical brain stimulation via tripolar concentric ring electrodes has been proposed as an alternative/complementary therapy for seizure control. Previous results suggest its efficacy attenuating acute seizures in penicillin, pilocarpine-induced status epilepticus, and pentylenetetrazole-induced rat seizure models and its safety for the rat scalp, cortical integrity, and memory formation.

Analysis of variance to assess statistical significance of Laplacian estimation accuracy improvement due to novel variable inter-ring distances concentric ring electrodes.

Concentric ring electrodes have shown promise in non-invasive electrophysiological measurement demonstrating their superiority to conventional disc electrodes, in particular, in accuracy of Laplacian estimation. Recently, we have proposed novel variable inter-ring distances concentric ring electrodes. Analytic and finite element method modeling results for linearly increasing distances electrode configurations suggested they may decrease the truncation error resulting in more accurate Laplacian estimates compared to currently used constant inter-ring distances configurations.

Proof of concept Laplacian estimate derived for noninvasive tripolar concentric ring electrode with incorporated radius of the central disc and the widths of the concentric rings.

Tripolar concentric ring electrodes are showing great promise in a range of applications including braincomputer interface and seizure onset detection due to their superiority to conventional disc electrodes, in particular, in accuracy of surface Laplacian estimation. Recently, we proposed a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2 that allows cancellation of all the truncation terms up to the order of 2n. This approach has been used to introduce novel multipolar and variable inter-ring distances concentric ring electrode configurations verified using finite element method.

A paradoxical response of the rat organism to long-term inhalation of silica-containing submicron (predominantly nanoscale) particles of a collected industrial aerosol at realistic exposure levels.

While engineered SiO nanoparticle toxicity is being widely investigated, mostly on cell lines or in acute animal experiments, the practical importance of as well as the theoretical interest in industrial condensation aerosols with a high SiO particle content seems to be neglected. That is why, to the best of our knowledge, long-term inhalation exposure to nano-SiO has not been undertaken in experimental nanotoxicology studies. To correct this data gap, female white rats were exposed for 3 or 6 months 5 times a week, 4h a day to an aerosol containing predominantly submicron (nanoscale included) particles of amorphous silica at an exposure concentration of 2.

Analytic assessment of Laplacian estimates via novel variable interring distances concentric ring electrodes.

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation has been demonstrated in a range of applications. In our recent work we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2.

Finite element method modeling to assess Laplacian estimates via novel variable inter-ring distances concentric ring electrodes.

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation has been demonstrated in a range of applications. In our recent work we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2.

In vivo toxicity of copper oxide, lead oxide and zinc oxide nanoparticles acting in different combinations and its attenuation with a complex of innocuous bio-protectors.

Stable suspensions of metal oxide nanoparticles (Me-NPs) obtained by laser ablation of 99.99% pure copper, zinc or lead under a layer of deionized water were used separately, in three binary combinations and a triple combination in two independent experiments on rats. In one of the experiments the rats were instilled with Me-NPs intratracheally (i.

Applying theoretical premises of binary toxicity mathematical modeling to combined impacts of chemical plus physical agents (A case study of moderate subchronic exposures to fluoride and static magnetic field).

Sodium fluoride solution was injected i.p. to rats at a dose equivalent to 0.

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes.

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2.

[Increasing resistance against hazardous effects of metals-containing nanoparticles as a prospective approach to health risks management].

Extremely high toxicity of metal-containing nanoparticles necessitates search of methods to increase body resistance against its harmful effects. The authors' experiments summarized in the article demonstrated that some combinations of certain biologically active substances selected according to sound theoretic background and prescribed in harmless doses can significantly decrease integral and specific manifestations of organ and system toxicity and even genotoxicity of such nanoparticles. Further development of this research direction should be recommended for practical implementation.

[Combined subchronic toxicity of nickel and manganese oxides nanoparticles, and its decrease due to bioprotectors complex].

Stable suspensions of NiO and/or Mn304 nanoparticles with average diameter 16,7?8,2 nm and 18,4?5,4 nm respectively, obtained via laser ablation of the metals with 99,99% purification in deionized water, were injected intraperitoneally into rats in dose of 0,5 mg or 0,25 mg three times per week up to 18 times separately or in various dose combinations. A group of rats received combined injections of nanoparticles in the highest dose or merely water with oral <> containing pectin, vitamins A, C and E, glutamate, glycine, N-acetylcysteine, selenium, iodine and polyunsaturated fatty acids of omega-3 class. Intoxication development was assessed through multiple functional parameters and histologic changes in liver, spleen, kidneys and brain.

Improving the accuracy of Laplacian estimation with novel multipolar concentric ring electrodes.

Conventional electroencephalography with disc electrodes has major drawbacks including poor spatial resolution, selectivity and low signal-to-noise ratio that are critically limiting its use. Concentric ring electrodes, consisting of several elements including the central disc and a number of concentric rings, are a promising alternative with potential to improve all of the aforementioned aspects significantly. In our previous work, the tripolar concentric ring electrode was successfully used in a wide range of applications demonstrating its superiority to conventional disc electrode, in particular, in accuracy of Laplacian estimation.

Some patterns of metallic nanoparticles' combined subchronic toxicity as exemplified by a combination of nickel and manganese oxide nanoparticles.

Stable suspensions of NiO and/or Mn3O4 nanoparticles with a mean diameter of 16.7 ± 8.2 nm and 18.

Attenuation of Combined Nickel(II) Oxide and Manganese(II, III) Oxide Nanoparticles' Adverse Effects with a Complex of Bioprotectors.

Stable suspensions of NiO and Mn₃O₄ nanoparticles (NPs) with a mean (±s.d.) diameter of 16.