Changes In Electrical Potential Research Articles

Application of a novel higher-order stretchable kinematic model for electro-elastic response analysis of constrained cylindrical shell

This article investigates impact of initial electric potential and parameters of Pasternak’s foundation on the higher-order electroelastic responses of cylindrical shell rested on the Pasternak’s foundation subjected to electromechanical loads. The mathematical modeling is performed using the higher-order thickness stretchable model including bending and shear parameters of deformation. The virtual work principle is used to derive governing equations. The results are analytically obtained in terms of main parameters of the shell. A verification study is presented before presentation of numerical results. The results are presented with changes of initial electric potential and two parameters of Pasternak’s foundation.

Disentangling heterogeneous thermocatalytic formic acid dehydrogenation from an electrochemical perspective

Heterogeneous thermocatalysis of formic acid dehydrogenation by metals in solution is of great importance for chemical storage and production of hydrogen. Insightful understanding of the complicated formic acid dehydrogenation kinetics at the metal-solution interface is challenging and yet essential for the design of efficient heterogeneous formic acid dehydrogenation systems. In this work, formic acid dehydrogenation kinetics is initially studied from a perspective of electrochemistry by decoupling this reaction on Pd catalyst into two short-circuit half reactions, formic acid oxidation reaction and hydrogen evolution reaction and manipulating the electrical double layer impact from the solution side. The pH-dependences of formic acid dehydrogenation kinetics and the associated cation effect are attributed to the induced change of electric double layer structure and potential by means of electrochemical measurements involving kinetic isotope effect, in situ infrared spectroscopy as well as grand canonical quantum mechanics calculations. This work showcases how kinetic puzzles on some important heterogeneous catalytic reactions can be tackled by electrochemical theories and methodologies.

3D-Oculography: New Method of Determination of Human Gaze Point Position in Space

INTRODUCTION: Oculography — a method of recording movement of eyeballs of a human or animal by analyzing changes in electrical potentials recorded by two electrodes fixed on skin near the eye socket is used to solve various problems. Among them are the determination of pronounced nystagmus, of characteristic changes of oculomotor reactions in different conditions of observing video images. Of interest is the determination of the position of gaze point (GP) and of the area of increased attention in three-dimensional space. This information is associated with the cognitive system of the observer and is of interest not only to physiologists, but also to specialists of related fields. . AIM: To experimentally prove the effectiveness of the developed method of 3D-oculography providing determination of the GP position in space. MATERIALS AND METHODS: The possibility of restoring GP position based on the analysis of recorded oculograms even in the presence of additive noise induced by the external electromagnetic fields, is proven by the numeric modeling method. Direct experimental studies were conducted with recording oculograms of a human observer on a previously verified equipment. A ZB-2 oculograph was used, the data obtained were verified by the method of average values. RESULTS: The obtained modeling results permitted to determine the maximal values of dispersion of additive noise and amplitude shifts of signals, which make possible satisfactory restoration of the coordinates of the GP and parameters of its movement trajectory. The qualitative correspondence of the experimental results to the results of numerical modeling was proven. The correspondence between trajectories of the observed object moving in space and trajectories of GP movement synthesized from counts of recorded oculograms was confirmed. CONCLUSION: Multichannel record of oculographic signals permits restoring parameters of the GP trajectory. Creating systems for recording these signals requires minimization of the noise level. An increase in dispersion of the noise component of the signal leads to most significant errors in calculating the coordinates of trajectory points.

Autonomous Thermal Modulator Based on Gold Film‐Coated Liquid Crystal Elastsomer

AbstractRadiative cooling has been recently intensively explored for thermal management and enhancing energy efficiency. Yet, traditional materials with singular emissivity fall short in dynamic thermal management, highlighting the need for materials that can adjust their thermal radiation in real time. Active modulation methods, requiring external stimuli such as mechanical stretch, electric potential, or humidity change, offer adaptability but can increase energy use and complexity. Passive approaches, using materials' inherent thermal‐responsive properties, face manufacturing and scalability challenges. Here, a scalable yet effective passive approach is introduced for adaptive thermal modulation based on gold (Au) and liquid crystal elastomer (LCE) with a reversible response to environmental temperature changes. This modulator enables a “low thermal resistance” state through actuation‐induced microcracks that expose a high‐emissivity polymer substrate, and a “high thermal resistance” state by closing these microcracks and forming a high thermal resistance air gap between the modulator and the target object. The flexible design and fixed external dimensions of the Au‐LCE thermal modulator make it adaptable to various surface geometries. Furthermore, by adjusting the LCE's chemical composition, the modulator's transition temperature can be tailored, broadening its applications from enhancing building energy efficiency to improving clothing thermal comfort.

The effect of ions on liquid-solid interface investigated by charge sensitive direct current droplet-based electricity generator

The contact electrification (CE) between DI water and SiO2 or fluorinated polymer has been proven to be mainly due to electron transfer, which is significantly influenced by ions in solution. However, how these ions in water affect the charge transfer at the liquid-solid (L-S) interface is still unresolved, especially for the already charged friction layer. Here, a direct current droplet-based electricity generator (DC-DEG) which is sensitive to the change of charge transfer at the L-S interface is adopted to detect the effects of ions in the neutral salt solution on the charged PTFE surface. The distribution of ions on the charged L-S interface (the change of electric potential on the solid surface) and its effects on the output of DC-DEGs have been studied. The results indicate that the charge transfer of droplets and then the output of DC-DEGs are closely related to the concentrations of salt solutions. Anions can enhance the surface potential of PTFE due to their adsorptions on PFTE while cations can reduce it due to their screen effect. At low ionic concentrations, the surface potential enhancement caused by anion adsorption is larger than that surface potential reduction caused by screen effect from cations. At high ionic concentrations, the electrostatic screen effect of cations increases a lot to weaken the surface potential and reducing the charge separation of droplets induced by electrostatic induction (EI). This work explains the redistribution process of ions at the L-S interface and also provides a clever solution for improving the electrical output performance of DEGs.

Early Detection of Peripheral Neuropathy by Assessment of Sudomotor Function

Chronic hyperglycemia in both type 1 and type 2 diabetes commonly lead to diabetic peripheral neuropathy (DPN) which commonly affects small nerve fibers, including autonomic sudomotor nerves, of the lower limbs. DPN results from nerve damage leading to gradual onset of foot pain, tingling, numbness, muscle weakness, extreme sensitivity to touch, and heat intolerance. Peripheral neuropathy is associated with increased all-cause mortality and morbidities such as foot ulcers, poor wound healing, local and systemic infection, limb amputation, and painful neuropathic symptoms. DPN is also typically diagnosed during later stages when disease progression has already led to irreversible nerve damage and associated severe symptoms. As such, early detection of peripheral neuropathy is important in implementing early interventions and can help preserve nerve function and prevent serious complications of DPN. Non-invasive methods of testing for early DPN rely on assessment of sudomotor nerve function. One method includes quantitative sudomotor axon reflex test (QSART) which measures postganglionic sympathetic function via iontophoresis which allows quantification of sweat production, and by extension, autonomic function. In general, QSART provides a non-invasive, reproducible, and precise evaluation of autonomic function in both controls and diabetics. It can be used to evaluate a large number of autonomic diseases, and the quantitative data it generates provides a measure of the extent and location of the peripheral neuropathy in each individual. Another assessment method includes the sympathetic skin response (SSR) test which measures the change in electrical potential of the skin which itself comes from activated eccrine sweat glands. The SSR test has a well-established protocol, and the results are easily-measured, and the results are quantifiable. It can be used reliably in the diagnosis of numerous autonomic disorders including DPN where a diminished or absent response correlate with sudomotor nerve damage. SudoCheck by VitalScan is an FDA-cleared, non-invasive autonomic sdomotor assessment tool that combines QSART, SSR, BIA, and EIS to provide rapid results with a specificity of 95% and a sensitivity of 80%. It was created to enable a precise evaluation of sweat gland function, and by extension, the presence and progression of diabetic peripheral neuropathy including early sub-clinical disease

A comprehensive study of a long-term creep thermo-mechanical fatigue behavior monitoring of BFRP composite pipeline using electrical capacitance sensors and deep learning algorithm

The composite pipeline is a relatively new and viable alternative pipeline to the more commonly used traditional one due to its good mechanical and fatigue properties and lower production cost. For this purpose, it is critical to assess the mechanical and fatigue performance of composite pipeline material under various working conditions, particularly for monitoring long-term creep thermo-mechanical fatigue behavior. In this paper, a long-term creep thermo-mechanical fatigue behavior in a basalt fiber reinforced polymer laminated composite pipeline is detected through an integrated expert system consisting of the electrical capacitance sensors and a deep learning algorithm. First, a multi-physics finite element model is established for the simulation of a long-term creep thermo-mechanical fatigue behavior in basalt fiber reinforced polymer composite pipelines subjected to long-term fatigue loading of internal pressure and thermal effect. Second, theoretical model results of long-term creep thermo-mechanical fatigue compliance (Sf(t)) over the time of creep are analyzed in pipeline material using the modulus degradation approach. Finally, an electrical potential change between electrical capacitance sensors electrodes corresponding to Sf(t) over the time of creep for some levels of long-term creep thermo-mechanical fatigue (Rf%) is recorded and then used in these datasets for training of the novel deep neural network based on one of the most widely used of the deep neural network families is the convolutional neural network, to predict Sf(t) in pipeline for various Rf% not included in the previous finite element model evaluation (i.e. electrical capacitance sensors technique). In this paper first is detected the long-term creep thermo-mechanical fatigue behavior for Rf%=25%,50%, and 75% from a finite element model and modulus degradation approach, and then is predicted the long-term creep thermo-mechanical fatigue behavior for Rf%=15%,35%,60%, and 85% respectively via deep neural network. The proposed method results are in good agreement with the experimental results available in the literature, thus verifying the accuracy and reliability of the proposed technique and its applicability to other different composite structures.

The Eleutherococcus senticosus fruits' intractum affects changes in the transepithelial electric potential in the distal section of the rabbit's large intestine and inhibits hyaluronidase

Ethnopharmacological relevanceEleutherococcus senticosus (Rupr. et Maxim.) Maxim. has been used in traditional Russian medicine due to its recognized immunostimulant and anti-inflammatory activities. Compounds present in the fruits have demonstrated the capability to modulate the activity of enzymes such as hyaluronidase, suggesting their potential value in the development of effective therapies for various conditions where anti-inflammatory properties are beneficial, such as gastrointestinal diseases and tumor growth. Aim of the studyIn order to support the use of the fruits in folk medicine, this study is aimed to evaluate, post-mortem, the impact of E. senticosus fruits intractum (40 % extract made from fresh fruits) on the transepithelial electrogenic transport of sodium ions in the colon. The objective of this study was also to examine the impact of the intractum on proinflammatory serum hyaluronidase in children diagnosed with acute leukemia. MethodsThe study employed the Ussing technique to examine electrophysiological characteristics of isolated epithelial tissue, using the distal colon wall isolated from 10 New Zealand white male rabbits. The effect of the intractum on the inhibition of human serum hyaluronidase was examined with turbidimetric screening methods, using the blood samples collected from patients diagnosed with acute leukemia. ResultsFor the first time, we discovered that the intractum used in the stimulation fluid, caused hyperpolarization reactions in colon tissue. Statistical analysis showed that these reactions were significantly different in relation to the control. The intractum significantly inhibited hyaluronidase activity with the mean value by group of 60 %, and 40 % for aescin used as a control. ConclusionThe results support the traditional use of the fruits in inflammatory-related diseases. The use of intractum of E. senticosus on the distal colon wall demonstrates its protective effect on the wall integrity and in a relation to hyaluronidase inhibition may additionally indicate its anti-inflammatory property. Thus, the results mean that the intractum may be used in colon-related diseases.

Response of photosynthesis and electrical reactions of wheat plants upon the action of magnetic fields in the Schumann resonance frequency band

ABSTRACT Alternating magnetic fields (MF) with Schumann resonance frequencies accompanied the development of living organisms throughout evolution, but today it remains unclear whether they can have a special biological effect in comparison with surrounding non-resonant frequencies. This work shows some stimulating effect of extremely low-frequency MFs on morphometric parameters and the activity of physiological processes in wheat (Triticum aestivum L.). It is shown that the MF effect is more pronounced for transient processes – photosynthesis reactions and changes in electrical potential caused by turning on light. For light-induced electrical reactions, the dependence of the severity of the effect on the frequency of the applied MF was demonstrated. It is shown that the most pronounced effect occurs in the 14.3 Hz field, which corresponds to the second harmonic of the Schumann resonance. The predominant sensitivity of signal-regulatory systems gives reason to assume the influence of MFs with Schumann resonance frequencies on the interaction of plants with environmental factors under conditions of a changed electromagnetic environment. Such conditions can occur, for example, with an increase in lightning activity caused by climate change, which serves as the basis for the generation of Schumann resonances, and with the development of artificial ecosystems outside the Earth’s atmosphere.

Investigation of guided wave propagation in nanoscale layered periodic piezoelectric plates based on Eringen's nonlocal and strain gradient theory

This paper investigates the dynamic propagation behavior of guided waves in nanoscale media composed of alternating layers of piezoelectric phases. The study employs Eringen's nonlocal and strain gradient theories to derive equations for symmetric wave propagation and the scattering relations of guided waves perpendicular to these structures. Dispersion curves are calculated and plotted to compare these theories, considering the influence of nanoscale size-effect, volume ratio of constituent layers, and material length scale. Using the strain gradient theory, the paper explores the impact of length scale parameters on the propagation behavior of horizontally polarized guided waves in an alternating layer structure of nanoscale piezoelectric material, specifically nanoscale piezoelectric laminates. The analysis involves calculating localization factors and dispersion curves to analyze the effects of size-effect and length scale parameters on wave propagation and band structures. Additionally, the study plots and analyzes changes in mechanical displacement and electrical potential, followed by an investigation and discussion of nanoscale size effects and the effects of the material's length scale parameter on dispersion curves and conversion modes within specific regions. The results highlight that the length scale effect parameter significantly impacts the mode conversion zones and band gap structures, more so than the NLPE continuum theory suggests. As the strain gradient parameter increases, these zones shift towards higher wavenumbers and to the right . Furthermore, introducing the length scale factor results in a substantial decrease in both the formation of conversion zones and the density of dispersion curves.

Albumin Protein Impact on Early-Stage In Vitro Biodegradation of Magnesium Alloy (WE43).

Mg and its alloys are promising biodegradable materials for orthopedic implants and cardiovascular stents. The first interactions of protein molecules with Mg alloy surfaces have a substantial impact on their biocompatibility and biodegradation. We investigate the early-stage electrochemical, chemical, morphological, and electrical surface potential changes of alloy WE43 in either 154 mM NaCl or Hanks' simulated physiological solutions in the absence or presence of bovine serum albumin (BSA) protein. WE43 had the lowest electrochemical current noise (ECN) fluctuations, the highest noise resistance (Zn = 1774 Ω·cm2), and the highest total impedance (|Z| = 332 Ω·cm2) when immersed for 30 min in Hanks' solution. The highest ECN, lowest Zn (1430 Ω·cm2), and |Z| (49 Ω·cm2) were observed in the NaCl solution. In the solutions containing BSA, a unique dual-mode biodegradation was observed. Adding BSA to a NaCl solution increased |Z| from 49 to 97 Ω·cm2 and decreased the ECN signal of the alloy, i.e., the BSA inhibited corrosion. On the other hand, the presence of BSA in Hanks' solution increased the rate of biodegradation by decreasing both Zn and |Z| while increasing ECN. Finally, using scanning Kelvin probe force microscopy (SKPFM), we observed an adsorbed nanolayer of BSA with aggregated and fibrillar morphology only in Hanks' solution, where the electrical surface potential was 52 mV lower than that of the Mg oxide layer.

Dodecanogram (DDG): Advancing EEG technology with a high- frequency brain activity measurement device

EEG measures electric potential changes in the scalp. Even though it has been associated with human thoughts, there has been no direct evidence. The problem with EEG is that it measures variations in current or electric potential in the millisecond time domain, where muscle movement strongly affects the readings. The millisecond time domain is equivalent to the kHz resonance signal generated by any dielectric resonator, and every single cell membrane resonates in this time range. So, the measurement of EEG could come simply from the skin and not from the brain. Therefore, we have advanced EEG technology with the dodecanogram (DDG), which reveals 12 frequency bands or 12 discrete time regions where brain activities are most significant. We measure brain activity using a stream of pulses and a logic analyzer that counts ultra-short pulses needed to emulate brain scalp potential changes. We have created another version of DDG where, using an array of RLC (resistor-inductor-capacitor) resonators, we sense the ultra-low-power electromagnetic radiation from different locations on the brain's surface. Since we measure signals from Hz to THz, covering 12 orders of time ranges as a property of dielectric resonance, unlike EEG, there is a high probability that the DDG signal may truly originate from the brain. We have monitored DDG on an artificial organic brain replica 24/7 for over a year and on multiple human subjects, before and after meditation and concluded that most cognitive, perceptive, and emotional bursts occur around 200-700 nanoseconds, not milliseconds, as it was believed for 150 years of EEG era.

Oxidative stress and energy metabolic response of Isochrysis galbana induced by different types of pristine and aging microplastics and their leachates

The aging process and leachate composition of different types of MPs (PS, PS-NH2, PS-COOH and PMMA) with a particle size of 1.0 μm were characterized, and marine microalgae Isochrysis galbana OA3011(I. galbana) was used as test organism to investigate the 96 h toxic effects of MPs before and after aging as well as leachate exposure. Except for polymethyl methacrylate (PMMA), all other tested microplastics showed significant aggregation in seawater, which increased with the presence of surface amino and carboxyl groups, in addition, the increase in polymer dispersibility index (PDI) values after aging reflected more severe aggregation. Fourier transform infrared spectrometer (FTIR) showed that the surface amino groups were shed during the aging of PS-NH2, which can likewise be demonstrated by the change in surface electric potential from positive to negative before and after aging. PMMA, due to the addition of plasticizers (HEHP and DIBP detected in high concentration) and its own structure, has stronger resistance to aging than the other three microplastics, and no significant aging phenomenon occurs. As for I. galbana, growth inhibition, oxidative stress and energy metabolism were tested after exposure to different microplastics and their leachate. It was found that high concentrations of A-PS had a greater negative impact on I. galbana, while the toxic effects of PS-NH2 and PS-COOH on I. galbana behaved in a diametrically opposite way before and after aging compared to PS with the inhibitory effect decreasing after aging, which was caused by the shedding of surface groups. As for PMMA, the differences in the toxic effects on microalgae before and after aging were not significant. The inhibitory effect of low concentrations of PAEs (Phthalate acid esters) in the leachate of PS-COOH on I. galbana was not significant, and the stronger inhibitory effect of 4 d L-PS-NH2 was presumed to be the shedding of positively charged groups.

Generalized piezothermoelasticity of hollow spheres under thermal shock using Lord–Shulman theory

Present investigation deals with the response of a piezoelectric hollow sphere that is subjected to sudden thermal shock. Loading and boundary conditions are assumed to be symmetric so the response of the sphere is also considered to be symmetric. The governing equations of the vessel are obtained which are three in number. These equations include the equation of motion, the energy equation and the Maxwell equation. The energy equation is established in the framework of single relaxation time theory of Lord and Shulman. The established equations are written in terms of temperature change, radial displacement, and electric potential. These equations are provided in a dimensionless presentation for the sake of generality. After that with the aid of the generalized differential quadrature method, the established equations are discreted. Also Newmark time marching scheme is applied to trace the radial displacement, electric potential, and temperature change in time domain. Novel numerical results are then provided to explore the propagation and reflection of electrical, thermal and mechanical waves in a hollow sphere. It is shown that temperature wave propagates with finite speed within the framework of the Lord–Shulman theory.

Determination of cell membrane permeability coefficients: Comparison of models in the case of oocytes

Values of cell membranes permeability coefficients for water and molecules of cryoprotective agents (CPAs) are the necessary characteristics for developing physical-mathematical models describing mass transfer processes through cell membranes in order to predict optimal cell cooling rates. We carried out a comparative analysis of the permeability coefficients of mouse oocyte membranes for molecules of water, ethylene glycol (EG), propane-1,2-diol (1,2-PD) and dimethyl sulfoxide (Me2SO), determined by applying the classical Kedem-Katchalsky model, which considers only the penetration of non-electrolyte molecules (water and CPA) through the membrane, and the model developed by us, which takes into account the transmembrane transfer of ions and the associated changes in the transmembrane electric potential. We shown that calculations based on the developed modified model provide lower values of the permeability coefficients of the oocyte membrane for water and CPA molecules. What is important that the obtained by our modified model permeability coefficients for water molecules do not depend on the type of cryoprotectant, while the application of the classical model both in our studies and works of other authors always gave different values of these coefficients in solutions with different cryoprotectants. Our modified model also makes it possible to determine the dynamics of the transmembrane electric potential of the cell under the conditions of transmembrane mass transfer and the duration of the membrane being influenced by the changes in electric potential, that is a parameter that can directly affect the viability of cells.

Light induced spiking of proteinoids

Proteinoids, or thermal proteins, are produced by heating amino acids to their melting point and initiating polymerisation to produce polymeric chains. In aqueous solutions proteinoids swell into hollow microspheres. These microspheres produce endogenous burst of electrical potential spikes and change patterns of their electrical activity in response to illumination. We report results on a detailed investigation on the effects of white cold light on the spiking of proteinoids. We study how different types and intensities of light determine proteinoids’ spiking amplitude, period, and pattern. The results of this study will be utilised to evaluate proteinoids for their potential as optical sensors and their application in unconventional computing.

Free vibration and nonlinear dynamic response of sandwich plates with auxetic honeycomb core and piezoelectric face sheets

This article analyses the nonlinear dynamic behavior and the free vibration of a piezoelectric auxetic honeycomb sandwich plate resting on a Pasternak elastic substrate. The plate includes two face sheets of piezoelectric material and an auxetic honeycomb core with a negative Poisson ratio. The first-order shear deformation plate theory, together with the von Kármán type nonlinear strain-displacement relationship, is used to establish the nonlinear equations of motion. Linear electric potential change with piezoelectric layer thickness is assumed. Two types of boundary conditions, namely immovable and movable simply supported, are considered. The displacement-time and acceleration-displacement curves under dynamic loads are determined by using the Galerkin and Runge-Kutta fourth-order methods. Verification examples have been performed and confirmed the accuracy of the model. Finally, several novel investigations have been conducted to evaluate the effect of material, geometrical parameters, and elastic substrate coefficients on the frequency and nonlinear dynamic characteristics of piezoelectric auxetic honeycomb sandwich plates for both open-circuit and closed-circuit operation.

Modelling and Optimization of the Differential Surface Capacitance in Electrolyte-Gated Graphene Field-Effect Transistors

Graphene field-effect transistors (GFETs) are a promising avenue for the detection of biomarkers, allowing to envision improvements in diagnostic approaches for different types of cancer and other diseases. To enable such applications, the detection metrics of the devices must be optimized, including their sensitivity, selectivity, and stability. In particular, the capacitance of the device is one of the key determinants of the sensitivity of the electrical current of graphene to nearby changes in electrical potentials. In this presentation, we present our approach to optimize the surface capacitance of electrolyte-gated GFETs, by investigating theoretically and/or experimentally the effect of specific design parameters, including the graphene area, the removal of the backgate, and the passivation of electrodes. On the theoretical side, a mathematical representation of the device capacitance was established as an equivalent circuit of capacitors modelling for the quantum capacitance of graphene, the backgate capacitance, and the capacitance of electrical double layers in the electrolyte. On the experimental side, microchips of GFET arrays were assembled using microfabrication techniques on two types of substrates: a standard Si++/SiO2 wafer in which the doped silicon layer is used as a backgate, and a pure non-conducting borosilicate glass wafer in comparison. The capacitance of the devices was then measured using a custom parallel electrical prober by stepping the applied voltage in the solution and analyzing the resulting current response through a standard RC direct current model. We will present our analyses by comparing the relative impact of electrode passivation, backgate usage, and graphene area on the capacitance of devices. These results will enable a rational design of GFET devices with improved sensitivity for their use in applications such as biological, chemical, and gas sensing.

Time-Dependent Features of Mass Transfer and Transmembrane Potential in Erythrocytes During Equilibration in Cryoprotective Solutions

On the basis of the developed physical and mathematical model of mass transfer, which takes into account the transmembrane transfer of non-electrolytes, basic ions and the associated changes in the transmembrane potential, the redistribution of osmotically active substances during equilibration of erythrocytes in cryoprotective solutions was investigated. Time parameters of changes in concentrations of osmotically active substances inside and outside cells, as well as transmembrane electric potential, were calculated. It is shown that during the exposure of human erythrocytes to 1M solutions of glycerol, 1,2-propanediol (1,2-PD) and dimethylsulfoxide (DMSO), the sign of their transmembrane electric potential changes three times, and in solutions of ethylene glycol (EG) and of acetamide (AA) – once. The analysis of the obtained results showed that the most acceptable for further cryopreservation from the point of view of erythrocytes reaching a state close to equilibrium in a 1M solution of glycerol was their equilibration for 5.5 min, and in solutions of DMSO, AA, EG and 1,2-PD with the same concentration – 1 min. At the same time, the cells remain somewhat dehydrated (by 5.5–7.5%), and the concentrations of cryoprotectants inside erythrocytes change insignificantly during longer exposure. The indicated degree of dehydration does not affect cell viability, but reduces the likelihood of intracellular ice formation during subsequent freezing.

Diurnal Variations in Vegetation Activity affecting Shallow Groundwater Flow identified by Microthermal Measurements

Observations of summer microthermal temperature variations suggest, next to hydrological factors, a significant influence of plant activity on groundwater flow in fractured claystone materials. Variations in groundwater microtemperature were compared to variations in meteorological parameters and electrical potential of plants. With an increase in surface temperature, relative air humidity decreases and an increase in tree electrical potential, measured as the difference between the northern and the southern stem exposure (N–S), can be observed. This increase in electrical potential is concomitant with a change in groundwater temperature of approximately 2 mK. This relationship does not always occur. At high temperatures (+30°C) the decrease amounts to just 1 mK. This fact is related to the change in transpiration of plants, decreased or even suspended at high surface temperatures. A frequency analysis of all data showed a daily frequency of high magnitude in all parameters. Possibly changes in the macro weather situation events were observed in the results of atmospheric pressure, southern electric potential and groundwater temperature. The lag time between changes in electric potential and subsurface microtemperature changes amounts to 17 hours, possibly a result of the electrical potential difference between the northern and the southern exposure of the stem (N–S), and 5 hours, the result of the change in electrical potential difference between the southern and the northern stem exposure side (S–N). A comparison between potential changes and the computed change in gravity resulting from earth tidal effects showed that the correlation between the subsurface temperature variation with up to 2 mK and the change in surface temperature variation does not match directly. Other study shows that the impact of earth tides on subsurface microtemperature variation amounts to ca. 1mK. The effect of groundwater abstraction by mature vegetation is determined at the same range. Atmospheric tides can be correlated with the changes in north and south electric potentials.