Poisson Effect Research Articles

Chemical Weapons in the Iran-Iraq War (1980–1988) 5. Accumulated Experience in the Treatment of Lesions Caused by Sulfur Mustard

ulfur mustard was widely used during the Iran-Iraq war (1980–1988) and in other conflicts in the Middle East. Due to its availability, it can be used by terrorist organizations on the territory of the Russian Federation. Iran is the only country, against which mustard gas was used in modern warfare. The aim of this work is to analyze and summarize the experience of treating of sulfur mustard exposure, accumulated by Iranian specialists during the Iran-Iraq war (1980–1988). The UN official documents and materials, declassified CIA documents, articles of Iranian authors as well as other open sources have been used during its preparation. The Iraqi army used mustard gas in two aggregate states: liquid and dry. Dry mustard gas was a novelty of that war. It was a powdered silica steeped in mustard gas, with a particle size of less than 5 μm. The first signs and symptoms of poisoning could appear after 15 minutes, while acute poisoning effects of exposure to mustard gas vapour or liquid were typically delayed for several hours. The reasons for the severe mustard lesions of the servicemen were the lack of personal protective equipment, untimely evacuation from the mustard gas contamination zone, and the absence of mobile reserves of clean water and degassing installations in battle formations. Iranian experts consider 0.5% sodium hypochlorite solution to be the most effective decontaminant. The only safe antidote is sodium thiosulfate, administered within 60 minutes after exposure to mustard gas. During the evacuation of victims and their treatment in hospitals it is necessary, in severe cases, to insert an intravenous catheter, carry out a tracheotomy with the installation of a tracheotomy tube, and use bronchoscopy as early as possible to flush the bronchi. The treatment of skin and eye lesions should be conservative. In case of a corneal perforation, if its diameter is more than 2 mm – keratoplasty, if it is less – cyanoacrylate glue. Treatment of respiratory lesions aims to relieve symptoms and reduce the severity of complications. For this, bronchodilators, antitussives, mucolytics and, if necessary, antibiotics are used. The use of corticosteroids should be limited to the treatment of those patients with bronchospasm, who can not be treated by bronchodilators. The Iranians also consider gene therapy and treatment with mesenchymal stem cells to be the promising method used in the treatment of lung lesions

Effect of Boronizing Treatment on the Conductivity of a High-Conductivity and Heat-Resisting Al-Zr Alloy Conductor Material

The effect of boronizing treatment on the conductivity of a high-conductivity and heat-resistant Al-Zr alloy conductor material was studied. The results showed that the conductivity of industrial pure Al containing transition element (Ti, V, Cr, Mn)>0.01 wt % (mass fraction, the same below) was improved to a certain extent by using boronizing treatment to remove transition metal elements through the formation of borides. Using the boronizing treatment, B can react with transition elements to form blocky (Ti, V, Fe)B2and flocculent (Ti, V, Fe, Zr)B2. The boronizing treatment makes Ti and V out of the solid solution state, form borides and finally deposit to the bottom of the furnace, thus significantly improving the conductivity of the ingot. In addition, Cr and Mn were not found in the borides at the bottom of the furnace. However, for the high-conductivity and heat-resisting Al-Zr alloy conductor material, B will have poison effects on Zr during boronizing treatment, thus reducing the heat-resistance of the alloy. Therefore, in the preparation process of high-conductivity and heat-resistant Al-Zr alloy conductor material, the converter process should be added after boronizing treatment to ensure that the Al-Zr alloy conductor material has good heat-resistance and conductivity at the same time.

Stretching-Tunable High-Frequency Magnetic Properties of Wrinkled CoFeB Films Grown on PDMS

We demonstrated a convenient method via applying uniaxial tensile strains to continuously tune the high-frequency properties of flexible magnetic films. CoFeB films were magnetron sputtered onto prestretched polydimethylsiloxane (PDMS) membranes. They exhibit a self-assembled periodic wrinkling surface structure because of the large mismatch of Young's moduli between the elastomeric PDMS substrates and the metal layers. The wrinkling morphology and the residual tensile stress caused by the Poisson effect can be continuously tuned by a uniaxial stretching strain less than the growth prestrain, which consequently results in changes in high-frequency performance. The initial permeability and the ferromagnetic resonance frequency of flexible CoFeB thin films can be monotonously tuned in wide ranges of about hundreds and 1 GHz, respectively. A good repeatability over thousands of stretching-relaxing cycles has been demonstrated without any obvious reduced high-frequency properties. This flexible CoFeB films with excellent stretching-tunable high-frequency performances are promising for application in flexible and tunable microwave devices.

A phase-field crack model based on a directional strain decomposition and a stress-driven Crack-Opening Indicator

We present a phase-field model for pre-cracked solids with a directional strain decomposition and a stress-driven crack-opening indicator (COI). We first introduce the COI to distinguish the opening and closure of pre-cracks and propose a novel criterion for solids based on the stress component in the direction of the crack surface normal. The stress-driven COI can correctly detect crack opening when principal strains have different signs, which cannot be achieved by most existing phase-field models. We then split the strain tensor into an effective part that induces stress and a crack-induced part that does not result in stress, and suggest a mapping tensor to transform the total strain tensor to the effective strain tensor. The mapping tensor is based on the crack surface normal, the phase variable, and the COI, thus leading to a directional decomposition of the strain. Eventually, we obtain the fourth-order material tangent mapping an arbitrary strain tensor to its stress tensor in the way that the shear stress along the crack surface vanishes and the normal stress in the crack surface normal direction is eliminated when the crack is open. Besides, owing to the directional strain decomposition, the direction where the stiffness decreases is invariant to the current strain once a diffusive crack is generated, which is physically more reasonable. More importantly, the decomposition together with the COI ensures that when the crack is open the spurious Poisson effect associated with the crack-induced strain is eliminated. Numerical examples are provided and the results have demonstrated the capability of the proposed model in simulating material behaviours in the post-fracture stage. Particularly, in a shear test of a squared plate with an initial crack, our model that simulates both the pre-crack and crack growth using the phase-field approach is able to reproduce the crack evolution pattern that has only been obtained in phase-field modelling by considering the initial crack as a geometric notch.

Metrological assessment of multi‐sensor camera technology for spatially‐resolved ultra‐high‐speed imaging of transient high strain‐rate deformation processes

AbstractThe present work proposes a metrological route for capturing spatially‐resolved ultra‐high‐speed kinematic full‐field data from high strain‐rate experiments and multi‐sensor camera technology. This paper focuses, from an application point of view, on highly resolved rotating mirror cameras, such as the Cordin‐580. This camera allows 78 frames of 8 megapixels to be recorded at up to 4 million frames per second (fps). The optical apparatus induces distortions that need to be taken into consideration. Distortions are modelled with Zernike polynomials and recovered using Digital Image Correlation (DIC) with a tailored synthetic speckle pattern. Effective displacements can then be quantitatively obtained with subpixel precision. After an assessment of the calibrated camera performance, this methodology is used to record, at 480,000 fps, the fracture of a pre‐notched sample subjected to an inertial impact test. The kinematic fields obtained quantitatively captured the events occurring during the test, such as the compression wave and the induced Poisson effect, the Mode‐I crack initiation and the shear strain concentration at the notch tip. The achievement of a DIC displacement and strain random error of, respectively, 5 μm (0.15 pixels) and 2 mm m−1, combined with a high spatio‐temporal sampling, provides a promising way for quantitatively analysing very fast transient and heterogeneous phenomena.

Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks

In this paper, we experimentally investigated two high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) stacks for their response to the presence of reformate impurities in an anode gas stream. The investigation was aimed at characterizing the effects of reformate impurities at the stack level, including in humidified conditions and identifying fault features for diagnosis purposes. Two HT-PEMFC stacks of 37 cells each with active areas of 165 cm2 were used with one stack containing a pre-doped membrane with a woven gas diffusion layer (GDL) and the other containing a post-doped membrane with non-woven GDL. Polarization curves and galvanostatic electrochemical impedance spectroscopy (EIS) were used for characterization. We found that both N2 dilution and impurities in the anode feed affected mainly the charge transfer losses, especially on the anode side. We also found that humidification alleviated the poisoning effects of the impurities in the stack with pre-doped membrane electrode assemblies (MEA) and woven GDL but had detrimental effects on the stack with post-doped MEAs and non-woven GDL. We demonstrated that pure and dry hydrogen operation at the end of the tests resulted in significant recovery of the performance losses due to impurities for both stacks even after the humidified reformate operation. This implies that there was only limited acid loss during the test period of around 150 h for each stack.

Nonlinear contact behavior of HTS tapes during pancake coiling and CORC cabling

Both the pancake coiling and conductor on round core (CORC) cabling processes consist of winding second-generation high-temperature superconducting tape (REBCO) in a core. The contact behavior between the tape and the core during the winding process directly affects the critical current, cable flexibility, mechanical support and electrical contact resistance. Therefore, the winding process needs to be optimized to produce pancake coils and CORC cables with the desired electrical and mechanical properties. This paper comprehensively considers the role of the relaxation and Poisson effects. The theoretical model and the finite element model (FEM) for calculating the contact stress during the winding process are established, and a formula for the estimation of the contact force is proposed. The suitable winding pre-tension force, winding curvature radius of SCS2030 (2 mm width and 30 m substrate thickness) and SCS4050 (4 mm width and 50 m substrate thickness) of REBCO tapes are obtained and discussed by accounting for the relaxation effect and the critical current degradation limit. With consideration of the Poisson effect, the nonlinear contact behavior is investigated. In addition, the relaxation effect, Poisson effect and plasticity of the REBCO tape are taken into account in the FEM model. The results show that the axial strain in the REBCO layer during the winding process is related to the contact behavior. The greater the winding pre-tension force, the smaller the helical curvature radius, and the greater the contact force. The distribution of contact stress for several winding factors (winding pre-tension force, winding angle and the core radius) is divided into three contact types: the single-line contact, the double-line contact and the surface contact. The FEM model results are consistent with the theoretical evaluation and are more suitable for practical winding cases. This research is the basis for designing and optimizing pancake coils and CORC cables.

Temperature effects on deformation substructures and mechanisms of a Ni-based single crystal superalloy

Mechanical behaviors of a Ni-based single crystal superalloy have been investigated by tensile testing at various temperatures. Deformation substructures and mechanisms have been systemically revealed from micrometer to atomic scales by using advanced scanning electron and scanning transmission electron microscopes. Results show that deformation mode of the alloy strongly depends on the temperature due to competitive responses of the γ and γ′ phases under mechanical loading and their original stress statuses. At temperatures from ambient to 750 °C, plasticity is governed by dislocation shearing in both phases, where slip modes of γ are <110>{111} and those of γ′ are <112>{111}, <110>{111} and <110>{001}. At moderate temperatures (850 °C ≤ T ≤ 900 °C), plasticity mainly involves microscopically uniform deformation of both phases. The matrix deforms first so that channels parallel to tensile direction are narrowed due to the Poisson's effect, after that deformation of γ′ follows. The active slip modes are <110>{111} for γ, <112>{111}, <110>{111}, <110>{001}, and <001>{001} for γ′. At temperature higher than 1000 °C, plastic strain is also derived from deformation of both phases, but deformation of the matrix plays critical roles, due to relatively weak strength of this phase. The operative slip modes are <110>{111} for γ, but mainly <110>{001} and <001>{001} for γ′. Our results clearly provide a comprehensive and multiscale (from micrometer to atomic) understanding on the deformation mechanism of Ni-based superalloys, which can be critically beneficial and offer mechanistic guidelines to design new/next generation superalloys.

Electro-induced shape memory effect of 4D printed auxetic composite using PLA/TPU/CNT filament embedded synergistically with continuous carbon fiber: A theoretical & experimental analysis

A novel strategy is proposed to fabricate continuous fiber-reinforced electro-induced shape memory auxetic composites (CFRSMCs) by combining conductive filaments and continuous carbon fiber through 3D printing technology. In the first step, the conductive filaments were manufactured based on Poly-lactic-acid/Thermoplastic-urethane/Carbon-nanotube (PLA/TPU/CNT) blend nanocomposite, and the CFRSMCs were then prepared, composing different carbonaceous fiber content with a variety of extrusion width. The main aim of the present work is to evaluate the mechanical, electrical, and thermal properties as well as the shape memory effect (SME). With regard to this, the negative Poisson's ratio effect of the printed CFRSMCs was precisely assessed through tensile measurement, and a well-adjusted theoretical model was employed for further predictions. Accordingly, as compared to free-fiber printed samples, the CFRSMCs exhibited superb mechanical properties and rapid electro-induced SME (a recovery ratio of 94% under 10 V within 25 s). Moreover, due to tailoring co-conductive networks by the CNTs and carbon fibers in the printed composites, a great deal of activation capability in the auxetic CFRSMCs could be revealed by various stimuli and for smart applications. This advanced strategy indicates a great potential to fabricate various auxetic electro-induced CFRSMCs used in small scale of deployable trusses or other lightweight smart components like adaptive energy absorption devices and human-scale orthopedic materials.

Analytical solution for a 5-parameter beam displacement model

In this paper, a new beam model based on a 5-parameter displacement field, accounting for an enhanced kinematics and able to reproduce the Poisson effect, is proposed. The displacement field enriches the classical three-parameter Timoshenko beam with two new parameters capable to simulate the shortening effect over the thickness. The related differential equations, derived from a variational formulation, are analytically solved and implemented in a deformation method approach, capable of solving structural problems of beams with general geometry, boundary and load conditions. Several numerical applications are developed, highlighting the characteristic of the proposed 5-parameters model and comparing the results with those obtained using the classical Bernoulli, Timoshenko and Reddy beam models. Numerical results show that, although for homogeneous beam the differences in terms of generalized stress and displacement are generally very small, the proposed model returns local stress enriched by the new parameters, with more significant differences where the Poisson effect is more pronounced.

RESEARCH ON THE CREEP OF CONCRETE FILLED STEEL TUBULAR COLUMNS BASED ON THE GENERALIZED KELVIN CHAIN

Concrete creep is an inherent time-dependent behavior of concrete and an important composition of structural responses. Its calculating method is usually established on the basis of uniaxial test and theory. To explore the creep behavior of concrete-filled steel tubular columns, the creep of circular concrete columns and concrete filled circular steel tubular (CFST) columns were measured by a self-made and self-balanced loading device. The results show that the creep deformation of CFST columns is smaller than that of concrete columns. In the present concrete creep tests, the maximum difference between the two aforementioned creep deformations was close to 50%. It is attributed to the fact that the core concrete cannot exchange moisture with its external atmosphere environment so that no dry shrinkage and creep of the core concrete occurred. It is also attributed to the confining pressure of the steel tube. According to the theory of viscoelasticity, a Volterra integral equation for solving the concrete creep under uniaxial stress condition was established by introducing a model consisting of a multi-parameter Kelvin element chain. The model parameters were approximately expressed as a successive retardation spectrum. Therefore, the constitutive relationship of concrete creep stress and strain increments under uniaxial stress condition was derived by discretizing the time variable t and integration by parts. Based on the principle of creep superposition and the Poisson effects, the constitutive model of the concrete creep stress and strain increments under uniaxial stress condition state was extended to a multiaxial stress state to analyze the CFST creep. The commercial finite element analysis software Ansys was secondarily-developed. The constitutive equation under multiaxial stress state for concrete creep performance was compiled with the Fortran language and introduced into the user subroutine Usermat of Ansys. Finally, the finite element numerical analysis for the long-term creep performance of CFST columns was carried out. Comparing the numerical solutions with the test results, it is found that the proposed method provides another effective approach to the analysis of concrete creep.

Assessment of negative poisson's ratio effect on thermal post-buckling of FG-GRMMC laminated cylindrical panels

This paper examines the thermal post-buckling behaviors of graphene-reinforced metal matrix composite (GRMMC) laminated cylindrical panels which possess in-plane negative Poisson's ratio (NPR) and rest on an elastic foundation. A panel consists of GRMMC layers of piece-wise varying graphene volume fractions to obtain functionally graded (FG) patterns. Based on the MD simulation results, the GRMMCs exhibit in-plane NPR as well as temperature-dependent material properties. The governing equations for the thermal post-buckling of panels are based on the Reddy's third order shear deformation shell theory. The von Karman nonlinear strain-displacement relationship and the elastic foundation are also included. The nonlinear partial differential equations for GRMMC laminated cylindrical panels are solved by means of a singular perturbation technique in associate with a two-step perturbation approach and in the solution process the boundary layer effect is considered. The results of numerical investigations reveal that the thermal post-buckling strength for (0/90)5T GRMMC laminated cylindrical panels can be enhanced with an FG-X pattern. The thermal post-buckling load-deflection curve of 6-layer (0/90/0)S and (0/90)3T panels of FG-X pattern are higher than those of 10-layer (0/90/0/90/0)S and (0/90)5T panels of FG-X pattern.

Mechanism of N2O generation over chromium poisoned γ-Fe2O3 catalyst during selective catalytic reduction of NOx with NH3

Poisoning effect of Cr in flue gas on the remarkable generation of greenhouse gas N2O over γ-Fe2O3 catalyst during selective catalytic reduction of NOx with ammonia was firstly observed in this work. At low temperature, N2O generation over Cr poisoned γ-Fe2O3 catalyst was attributed to non-selective catalytic reduction (NSCR) of NOx. At high temperature, NSCR of NOx and ammonia peroxidation accompanying by weak NO disproportionation induced a more generation of N2O. The seeming promotion effect of Cr on NOx conversion of γ-Fe2O3 catalyst at low temperature was partly resulted from the NSCR of NO which also contributed to NOx conversion. At high temperature, the reduction of NOx to innocent N2 was far inhibited after chromium poisoning in view of the low selectivity of NO to N2. The formed FeCr2O4 in chromium poisoned γ-Fe2O3 catalyst was the induction factor for large N2O production, which enhanced the acidity and reducibility of catalyst. Transient DRIFTS results indicated that SCR and NSCR of NOx over chromium poisoned γ-Fe2O3 catalyst predominantly happened via Eley-Rideal mechanism. Moreover, O2 in flue gas determined the activation of adsorbed NH3 and which dictated the NSCR of NOx and ammonia peroxidation.

Pencegahan Keracunan Pestisida pada Ibu Hamil Di Daerah Pertanian Hortikultura

Pesticide poisoning is a critical problem in agricultural health, especially horticultural agriculture. Excessive doses of pesticides are used from seedling until the plants are ready for harvest, and improper handling and PPE use. Anemia is one of the chronic effects of pesticide poisoning. In pregnancy, anemia can result in impaired intrauterine growth so that the baby is born LBW and stunted. Community service aims to increase pregnant women's knowledge on the risks of exposure to pesticides and to check cholinesterase and Hb levels. The results showed an increase in knowledge of safe pesticide handling in most participants (90%). The health check found that 30% of pregnant women have poisoned and 16% anemia, indicating high exposure and low self-protection. We also developed a pesticide management pocketbook and distributed it to all participants. Another 500 copies were given to the West Lampung Health Office to be distributing to pregnant women in other areas. This service activity can be carried out sustainably and involve many partners.

Selenium ligands doped ZnS for highly efficient immobilization of elemental mercury from coal combustion flue gas

At the upstream of electrostatic precipitator (ESP) or bag house (BH), using sorbents with excellent adsorption capacity is a common method for capturing mercury (Hg) from coal-fired power plant flue gas. ZnS, an inexpensively and conveniently prepared metal sulfide, can even be collected from nature, and is a promising candidate for its sulfur resistance. In this work, selenium ligands (Se 2− and Se 0 ) were introduced into ZnS for enhancing Hg 0 capture capability. The experimental results showed that the Hg 0 removal efficiency can reach 100% in a wide temperature range from 40 ℃ to 300 ℃ when the Se ratio was 30 wt% (30SZ). Compared with pure ZnS and Se powder, Se/ZnS were all exhibited an excellent absorbent capability. A long term experiment was imposed on 30SZ, and the sample adsorption capacity remained unchanged. Moreover, O 2 and SO 2 had insignificant effects on Hg 0 adsorption, NO showed a slight competition for Hg 0 adsorption. It was found that Se ligands (Se 2− and Se 0 ) and surface active S (S 2- and S) sites immobilized Hg 0 over the Se/ZnS surface, and in turn the adsorbed Hg 0 was basically converted to HgSe and HgS, and the adsorption mechanism was also proposed. With these advantageous performances, 30SZ is expected to be an economically feasible and scientifically sound sorbent. This work also provides a promising way for Hg 0 capture from coal combustion flue gas. • Inactive synthesized ZnS were functionalized to be highly efficient mercury sorbents. • The removal efficiencies can reach 100% in a wide temperature range from 40 to 300 ℃. • Se/ZnS had higher binding energy of Hg-Se to improve the adsorption capability. • The captured mercury is mainly converted into HgSe by chemisorption. • The components in the SFG have no obvious poison effects to synthesized 30SZ.

Strain Tensor Imaging: Cardiac-induced brain tissue deformation in humans quantified with high-field MRI

The cardiac cycle induces blood volume pulsations in the cerebral microvasculature that cause subtle deformation of the surrounding tissue. These tissue deformations are highly relevant as a potential source of information on the brain's microvasculature as well as of tissue condition. Besides, cyclic brain tissue deformations may be a driving force in clearance of brain waste products. We have developed a high-field magnetic resonance imaging (MRI) technique to capture these tissue deformations with full brain coverage and sufficient signal-to-noise to derive the cardiac-induced strain tensor on a voxel by voxel basis, that could not be assessed non-invasively before. We acquired the strain tensor with 3 mm isotropic resolution in 9 subjects with repeated measurements for 8 subjects. The strain tensor yielded both positive and negative eigenvalues (principle strains), reflecting the Poison effect in tissue. The principle strain associated with expansion followed the known funnel shaped brain motion pattern pointing towards the foramen magnum. Furthermore, we evaluate two scalar quantities from the strain tensor: the volumetric strain and octahedral shear strain. These quantities showed consistent patterns between subjects, and yielded repeatable results: the peak systolic volumetric strain (relative to end-diastolic strain) was 4.19⋅10−4 ± 0.78⋅10−4 and 3.98⋅10−4 ± 0.44⋅10−4 (mean ± standard deviation for first and second measurement, respectively), and the peak octahedral shear strain was 2.16⋅10−3 ± 0.31⋅10−3 and 2.31⋅10−3 ± 0.38⋅10−3, for the first and second measurement, respectively. The volumetric strain was typically highest in the cortex and lowest in the periventricular white matter, while anisotropy was highest in the subcortical white matter and basal ganglia. This technique thus reveals new, regional information on the brain's cardiac-induced deformation characteristics, and has the potential to advance our understanding of the role of microvascular pulsations in health and disease.

Potential significance of medicinal plants in forensic analysis: A review.

Medicinal plants are a two-edged sword that might be exploited as a treatment specific dosage, and as deadly poisonous substances to commit murder or suicide when administered in high doses. Forensic experts can collect traces and residual materials from these toxic medicinal plants at a crime scene as forensic evidence. Further, more investigations need to be deeply implemented to in the future to understand the significance of medicinal plants in forensic investigations to detect these criminal offenses. Additionally, to provides a deep understanding of chemical substances that can impact human life positively or negatively with different doses as well as identifying the optimal or overdose concentrations for either treatments or poisonous effects using recent biotechnological approaches. This review aims to illustrate different contributions and the significance of medicinal plants in the field and further employment in the context of forensic science, especially in the Kingdom of Saudi Arabia.

Bending-torsional behavior analysis using a refined beam theory

Abstract: In this paper, the bending-torsional behavior analysis of a functionally graded material (FGM) cantilever beam (I-section) was studied using a high-order theory, called refined beam theory (RBT) based on the 3D solution of Saint-Venant(SV). This theory takes into account the effects of edges to describe a larger three-dimensional solution inside the beam. The model includes a set of deformations that reflect the mechanical behavior of the FGM beam, in order to describe a larger three-dimensional solution inside the beam (Poisson's effects, out-of-plane warpings, and distortions). These deformations are related to both the shape and materials of the section. To study this beam and apply this theory, an easy-to-use tool called Cross-Section and Beam analysis (CSB) was used. The Young's modulus of an FGM cantilever beam varies through-thickness by the power-law distribution. The results obtained were compared with those obtained with the 3D/SV solution. Mots-clefs: FGM, bending, torsional, power-law, Young's modulus

Predicting an ideal 2D carbon nanostructure with negative Poisson's ratio from first principles: implications for nanomechanical devices

The intrinsic negative Poisson’s ratio effect at the level of molecule in two-dimensional nanomaterials, especially in the perfect planar nanostructures with a single atom thickness, is really rare and has attracted a lot of research interests because of its unique mechanical properties in the nanoscale and extensive applications in mechanical nanodevices. In this work, a novel ideal planar carbon nanostructure (PCNS) framework with a single atom thickness composed by carbon and hydrogen atoms is proposed and studied by means of first-principles density functional calculation. The results showed that the PCNS is, simultaneously, of excellent thermodynamic, molecular dynamic and mechanical stabilities. In addition, the electronic structure, mechanical characters, and optical-electronic characteristics of PCNS are also explored. Excitedly, it is found that the PCNS has a significant negative Poisson's ratio effect in plane, and the maximum value of Poisson's ratio is as high as − 2.094. Meanwhile, the material has a wide range of elastic mechanics. Moreover, the PCNS presents an ideal UV absorption performance. It is hoped that this work could be a useful structural design strategy for the development of the ideal 2D carbon-based nanomechanical devices with the intrinsic negative Poisson’s ratio effect and other electronic functions. An ideal 2D carbon nanostructure with negative Poisson's ratio was designed and its properties were investigated from first principles calculation.

Behavioural and morphological changes in rats with lead poisoning aggravated by medicinal hypothyroidism

Relevance. Metals are transported by run-off from human settlements and industrial plants and accumulate in the sediments of water bodies. Lead is found in high concentrations in the soil of agricultural land. Lead can be transported with water, seafood, animal products and plants to humans. Poisoning may occur in workers and in the population in contact with lead. At the same time, hypothyroidism is a widespread disease, often due to living in areas of endemic iodine deficiency in water and soil. Latent hypothyroidism can aggravate occupational effects of heavy metals in exposed workers.Intention. To study behavioural and morphological changes in rats with lead poisoning aggravated by medicinal hypothyroidism. Methodology. 32 albino outbred adult male rats were studied. Lead poisoning was induced by lead acetate at a dose of 60 mg/kg body weight in drinking water tanks for 30 days. Hypothyroidism in rats was induced from the ninth day of the experiment with daily injections of thyrozol (thyroid static substance) at a dose of 30 mg/kg for 21 days. Behavioral responses in rats were studied using open field tests, and survey records were processed using Real Timer. For morphological analysis, layered serial cuts of brain tissue were prepared and painted using the Nissl method, and slides were visualized via observation microscopy.Results and Discussion. Under lead poisoning, animals demonstrated decreased locomotor and exploration activity and increased anxiety with increasing intoxication combined with hypothyroidism. Changes in the rat brain after exposure to lead were confirmed histologically: increased neuron degeneration, neuronophagia and glyosis. New histological data were obtained in case of lead-thyrozol combination: increased neuronal death, decreased number of astroglial cells compared to animals exposed to lead only. This suggests predominant irreversible neurodegeneration due to combined effects of lead poisoning and thyroidstatic exposure.Conclusion. Under combined exposure to lead and tyrozol, the thyroidstatic substance exacerbated decline in locomotor and exploration activity as well as lead-associated neurodegenerative processes in the rat brain.