Figure 1 - uploaded by Elki Souza
Content may be subject to copyright.
Source publication
Walther Hermann Nernst received the Nobel Prize in Chemistry in 1920 for the formulation of the third law of thermodynamics, thus celebrating a century in this 2020 year. His work helped the establishment of modern physical chemistry, since he researched into fields, such as thermodynamics and electrochemistry, in which the Nernst equation is inclu...
Context in source publication
Context 1
... two compartments are interconnected by an ionic conductor, called salt bridge (FATIBELLO-FILHO, 2019;MARTINS, 1990;MCSWINEY, 1982). A schematic representation of the Daniell galvanic cell is provided in Figure 1 and follows are the halves and overall reactions that occur in the cell. The standard potential (E°) values are tabulated (WOLYNEC, 2003;MOORE, 1976) for the electrodes as follows: copper (couple (Cu 2+ /Cu)) reduction = 0.34 V and zinc (couple (Zn 2+ /Zn)) = 0.76 V, both relative to hydrogen potential at 25 °C and 1 atm pressure. ...
Citations
... 85,96 Overall, the Nernst equation represents the quantitative relationship between a potentiometric cell's potential and the activity of a target ion in theoretical conditions, so the measurements based on this equation describe the ideal response. 97 Hence, the Nernst theoretical slope of 29.6 mV/decade or 59.2 mV/z is frequently compared to the experimental response slope to explain whether Nernstian behavior occurred. 98,99 ...
The increasing level of atmospheric carbon dioxide (CO2) driven by human activities contributes to the global concern of climate change. A consequence of these circumstances is ocean acidification, which reduces seawater pH. The increasing absorption of atmospheric CO2 into the ocean decreases the concentration of carbonate ions and causes the sea to become more acidic, severely harming marine species. This harm to marine life has created the need for in situ carbonate sensing and monitoring to understand how marine ecosystems respond to pH reduction. Over the past few decades, many sensors with different compositions and structures have been developed to detect carbonate in seawater and other aquatic environments to simulate oceanic conditions. This review summarizes the recent developments in carbonate ionophores, a key component in carbonate electrochemical sensors, and compares the reported performance of these sensors through various parameters (e.g., sensitivity, response time, lifetime, testing media, and measuring range). Current challenges within the development of carbonate ionophores and sensors and possibilities for future research are also discussed.
... Damage to these barriers due to disease, acute cerebral trauma, and cancers are known to alter permeability resulting in infiltration of leukocytes and small molecules [62][63][64][65]. The extracellular milieu in the cranial vault is highly regulated, and as such, millimolar changes in ion concentrations within the extracellular space drive changes in neuronal membrane potential, ultimately altering the excitability of neurons [66]. Milieu changes also alter the chemotactic capacity of microglia and astrocytic activity [57,67]. ...
Tuberculosis meningitis (TBM) carries the highest morbidity and mortality of any type of tuberculosis infection, yet the definitive mechanism(s) that result in TBM are largely unknown.
Microglia as a bridge between the immune and nervous systems and its role in age related physiological changes that may lend some insight into why TBM is prevalent in pediatrics.
There are various hypotheses on how Mycobacterium tuberculosis, the etiological agent of tuberculosis, disseminates from the lungs to the central nervous system but these routes have been unobserved in existing animal models. This review aims to highlight the neuroimmunology of TBM, highlights the importance of age-dependent physiological changes, and recommends techniques commonly used in neurobiology to generate a more complete picture of TBM pathogenesis. We argue that age is an important consideration because TBM typically presents in children less than 5 years old. We hope that increasing the prevalence of longitudinal studies in TBM research with respect to age will aid in identifying definitive mechanism(s) that result in TBM and improve clinical outcomes.
... The cyclic voltammetry (CV) measurements were done at different scan rates (from 5 to 200 mV s −1 ) to identify the charge storage and charge transfer behaviors of nanocomposite. The CV curve describes the Nernst equation which relates the potential of an electrochemical cell (E) to the standard potential (E°) and the equation is 50 : Figure 7a-e shows the CV curves for PS, PS/rGO, and PS/rGO/MoS 2 nanocomposites. All of the curves show the sharp increment of current density in the forward scan rate and drop sharply in the reverse scan. ...
A ternary nanocomposite of plasticized starch (PS), reduced graphene oxide (rGO), and molybdenum disulfide (MoS2) was prepared via a solution casting process, with MoS2 concentrations ranging from 0.25 to 1.00 wt%. The structural, surface morphological, optical, and electrochemical properties of the nanocomposites were studied. FTIR analysis reveals the formation of new chemical bonds between PS, rGO, and MoS2, indicating strong interactions among them. The XRD analysis showed a reduction in the crystallinity of the nanocomposite from 40 to 21% due to the incorporation of nanofiller. FESEM micrograph showed an increment of the surface roughness due to the incorporation of rGO-MoS2 layers. UV–vis spectroscopy demonstrated a reduction of optical bandgap from 4.71 to 2.90 eV, resulting from enhanced charge transfer between the layers and defect states due to the addition of nanofillers. The incorporation of MoS2 increase the specific capacitance of the PS from 2.78 to 124.98 F g⁻¹ at a current density of 0.10 mA g⁻¹. The EIS analysis revealed that the nanofiller significantly reduces the charge transfer resistance from 4574 to 0 Ω, facilitating the ion transportation between the layers. The PS/rGO/MoS2 nanocomposite also exhibited excellent stability, retaining about 85% of its capacitance up to 10,000 charging-discharging cycles. These biocompatible polymer-based nanocomposites with improved electrochemical performance synthesized from an easy and economical route may offer a promising direction to fabricate a nature-friendly electrode material for energy storage applications.
... The sensor's calibration curves were based on the Nernst Equation (4), where RT/F = 0.05916, E° is the standard electrode potential at 25 °C, T is the temperature in kelvin, R is a universal gas constant, and F is the Faraday constant [54][55][56]. ...
... The value of the detection limit was obtained by extrapolating the data line until the intercept with the pHaxis [57,58]. The sensor's calibration curves were based on the Nernst Equation (4), where RT/F = 0.05916, E • is the standard electrode potential at 25 • C, T is the temperature in kelvin, R is a universal gas constant, and F is the Faraday constant [54][55][56]. ...
In this study, anodic aluminum oxide membranes (AAOMs) and Au-coated AAOMs (AAOM/Au) with pore diameters of 55 nm and inter-pore spacing of 100 nm are used to develop ZnO/AAOM and ZnO/ZnAl2O4/Au nanoarrays of different morphologies. The effects of the electrodeposition current, time, barrier layer, and Au coating on the morphology of the resultant nanostructures were investigated using field emission scanning electron microscopy. Energy dispersive X-ray and X-ray diffraction were used to analyze the structural parameters and elemental composition of the ZnO/ZnAl2O4/Au nanoarray, and the Kirkendall effect was confirmed. The developed ZnO/ZnAl2O4/Au electrode was applied to remove organic dyes from aqueous solutions, including methylene blue (MB) and methyl orange (MO). Using a 3 cm2 ZnO/ZnAl2O4/Au sample, the 100% dye removal for 20 ppm MB and MO dyes at pH 7 and 25 °C was achieved after approximately 50 and 180 min, respectively. According to the kinetics analysis, the pseudo-second-order model controls the dye adsorption onto the sample surface. AAOM/Au and ZnO/ZnAl2O4/Au nanoarrays are also used as pH sensor electrodes. The sensing capability of AAOM/Au showed Nernstian behavior with a sensitivity of 65.1 mV/pH (R2 = 0.99) in a wide pH range of 2–9 and a detection limit of pH 12.6, whereas the ZnO/ZnAl2O4/Au electrode showed a slope of 40.1 ± 1.6 mV/pH (R2 = 0.996) in a pH range of 2–6. The electrode’s behavior was more consistent with non-Nernstian behavior over the whole pH range under investigation. The sensitivity equation was given by V(mV) = 482.6 + 372.6 e−0.2095 pH at 25 °C with R2 = 1.0, which could be explained in terms of changes in the surface charge during protonation and deprotonation.
... Fuel cells need hydrogen to produce electrical power. Producing hydrogen needs electrical power [12]. Using the variable produced power from a renewable source to produce hydrogen and then using the hydrogen to produce constant power through a fuel cell is called power to hydrogen to power systems (P2H2P) [8]. ...
this paper presents an overview of power-to-hydrogen-to-power (P2H2P) systems as insignificant producers of greenhouse gases (GHG). In addition, the dynamic performance of SOFC is presented along with its simulated mathematical model, and control strategies. Two control strategies of grid-connected SOFC are considered. These are the constant power and constant current control strategies. The results show that the constant current control strategy surpasses the constant power strategy in achieving the most of the desired control and operation signals.
... Secondly, it suggests whether ions are transported actively or passively (Fageria et al., 2006;Farhangi-Ab riz, and Ghassemi-Golezani, 2023). When Nernst equation is employed in computing electrical potentials, negative values designate passive uptake and positive values show passive uptake for anions (Mengel and Kirkby, 1978;Ciribelli et al., 2020). Measurements are only effective when equilibrium state is sustained in the system, which according to Fageria et al. (2006), is difficult under practical situations. ...
Nutrient demands of plants are fulfilled via nutrient uptake by the roots, even though minor quantities of certain nutrients might be assimilated via leaves. For the reason that the majority of nutrients are assimilated by roots, an understanding of root morphology and cell structure is crucial in knowing this basic plant process. Nutrient achievement by plants hinges on ion applications on superficial, root assimilation capacity, and plant requirement. Movement of ion in plant cells is classified into active and passive. Ion concentrations in the cytoplasm of plant cells are frequently and considerably observed to be greater than in soil solutions. Consequently, roots ought to be able to take up ions in contrast to broadly diverse concentration gradients. Currently, two major theories of ion transport across membranes are reported in literature: carrier theory where carrier agents accountable for transferring ions from one side of membrane to the other; encounter specific ions for which they have attraction, form carrier ion complexes; and move across membranes and connecting ATPase theory of ion transport; which is related with the plasmalemma and is activated by cations; the ion pump theory, which is a demanding proces, transporting via electrochemical gradient. Measurements of ion uptake could be achieved through tracer techniques. Long-distance transport of ions to shoots happens in the vascular system, with water being the transporting agent. New and stimulating developments in mineral uptake mechanism of plants have momentously added to our understanding of the function of nutrients uptake in plants. Most research comparative to physiology of nutrient uptake has been conducted under controlled environment by means of particular nutrient cultures in the growth medium.
... Finally, the sensor electrode lifetime is investigated by utilizing the same calibration measurement behaviour over a buffer of pH 3.0-10 for several weeks. The calibration curves for the sensor are based on the Nernst Equations (1) and (2), where n represents oxidation electrons, Q represents H + ions concentrations, T represents temperature in kelvin, R represents a universal gas constant, and F represents the Faraday constant, with RT/F = 0.0591 at 25 • C [36][37][38][39]. ...
... Finally, the sensor electrode lifetime is investigated by utilizing the same calibration measurement behaviour over a buffer of pH 3.0-10 for several weeks. The calibration curves for the sensor are based on the Nernst Equations (1) and (2), where n represents oxidation electrons, Q represents H + ions concentrations, T represents temperature in kelvin, R represents a universal gas constant, and F represents the Faraday constant, with RT/F = 0.0591 at 25 °C [36][37][38][39]. ...
Porous anodic alumina membranes coated with Pt nanoparticles (PAAM/Pt) have been employed as pH sensor electrodes for H+ ion detection. The PAAM was designed using a two-step anodization process. Pt nanoparticles were then sputtered onto the membrane at different deposition times. The membrane’s morphological, chemical, and optical characteristics were carefully assessed following the fabrication stage using a variety of analytical techniques. The potential of the PAAM/Pt sensor electrode was investigated by measuring the potential using a simple potentiometric method. The effects of depositing Pt nanoparticles for 3–7 min on sensor electrode sensitivity were examined. The optimal potentiometric Nernstian response slope for the PAAM/Pt sensor electrode with 5 min Pt sputter coating is 56.31 mV/decade in the pH range of 3.0 to 10 at 293 K. Additionally, the PAAM/Pt sensor electrode’s stability and selectivity in various ions solutions were examined. The sensor electrode had a lifetime of more than six weeks and was kept in a normal air environment.
... The number of atoms that were diffused was influenced by the concentration gradient of the solution near the electrode. The concentration gradient value was influenced by the concentration of the solution near the electrode and the rate of diffusion of the electrolytes through the solution [50]. Therefore, a faster change in voltage causes a larger concentration gradient near the electrode and produces a larger current. ...
The development of silver (Ag) thin films and the fabrication of Ag nanosquare arrays with the use of an anodic aluminum oxide (AAO) template and leaf extracts were successfully carried out using the DC sputtering and spin coating deposition methods. Ag thin films and Ag nanosquare arrays are developed to monitor cancer prognosis due to the correlation between serum albumin levels and prognostic factors, as well as the binding of serum albumin to the surface of these electrodes. Nanosquare structures were fabricated using AAO templates with varying diameters and a gap distance between adjacent unit cells of 100 nm. The nanosquare array with a diameter of 250 nm and irradiated with electromagnetic waves with a wavelength of around 800 nm possessed the greatest electric field distribution compared to the other variations of diameters and wavelengths. The results of the absorption measurement and simulation showed a greater shift in absorption peak wavelength when carried out using the Ag nanosquare array. The absorption peak wavelengths of the Ag nanosquare array in normal blood and blood with cancer lymphocytes were 700–774 nm and 800–850 nm, respectively. The electrochemical test showed that the sensitivity values of the Ag thin-film electrode deposited using DC sputtering, the Ag thin-film electrode deposited using spin coating, and the Ag nanosquare array in detecting PBS+BSA concentration in the cyclic voltammetry (CV) experiment were 1.308 µA mM−1cm−2, 0.022 µA mM−1cm−2, and 39.917 µA mM−1cm−2, respectively. Meanwhile, the sensitivity values of the Ag thin film and the Ag nanosquare array in detecting the PBS+BSA concentration in the electrochemical impedance spectroscopy (EIS) measurement were 6593.76 Ohm·cm2/mM and 69,000 Ohm·cm2/mM, respectively. Thus, our analysis of the optical and electrochemical characteristics of Ag thin films and Ag nanosquare arrays showed that both can be used as an alternative biomedical technology to monitor the prognosis of blood cancer based on the concentration of serum albumin in blood.
The rising demand for electricity is becoming a tread throughout the world. In this study, a modified Zn/Cu electrodes-based bio-electrochemical cell (BEC) has been developed by using the ginger extract electrolyte and silver nanoparticles (Ag NPs). The effect of Ag NPs on the open circuit voltage (V), short circuit current (I), maximum power (P), power density (Pd), and internal resistance (R) of the BEC has been examined. Here, Ag NPs were formed via a rapid, non-toxic green synthesis process by using the ginger extract reducing agent. The functional groups in the ginger extract play an important role in reducing the Ag NPs from the Ag ions. The formation of Ag NPs was probed by X-ray diffraction spectroscopy (XRD) and UV–visible spectroscopy, and the active functional groups presented in the plant extract have been identified by using the Fourier transform infrared (FT-IR) analysis. The Ag NPs were incorporated in BEC to integrate the power and power density of cell. Such a modified Zn/Cu-based BEC can take the frontier forward for the integration of nanotechnology in low-cost electricity generation.KeywordsGinger extractReducing agentBio-electrochemical cellAg NPsElectricity
