Polarization Studies Research Articles

Evaluation of Corrosive Properties of Hafnium Nitride Coating Over Titanium Screws: An In Vitro Study.

Background Varied surface coatings have been studied time and again in medical sciences. Whether general or dental, studying the performance of coatings aims to assess their potential to improve the durability and longevity of titanium implants, thereby advancing implant technology for enhanced patient outcomes. Various analytical techniques are utilized to assess the performance of the coating, providing insights into its effectiveness in preventing corrosion. The findings of this evaluation will contribute to our understanding of corrosion mitigation strategies for titanium implants and pave the way for the development of more durable implant materials. This article aims to evaluate the corrosion resistance of an innovative metal compound coating applied over titanium implants. Materials and methods In this study, a total of 20 medical-grade, commercially pure titanium screws were collected. The dimensions of the titanium screws were 2mm x 7mm. Around 10 of these commercially pure titanium screw samples were used as the control group. Hafnium nitride (HfN) (0.1 M) was mixed with 100% ethanol and stirred using a glass rod for about 48 hours. Then 10 of the implant screw samples were immersed in the prepared sol and sintered at 400o C for two hours. The HfN-coated samples were then used as the test group. The corrosion resistance of both groups was tested using electrochemical impedance spectroscopy and potentiodynamic polarization studies. The Nyquist, Bode impedance, and Bode phase angle plots were obtained and studied. Results Using the Stern-Geary equation, the corrosion current density was calculated. On analysis, these values indicated that the higher impedance in HfN-coated titanium screws showed higher mean corrosion potential (Ecorr = -0.452 V) andcorrosion current density ( icorr = 0.0354 μA/cm2) than the uncoated titanium screws. Conclusion It was concluded that the corrosion properties of HfN-coated titanium screws had higher impedance and consequently the highest corrosion resistance. This thereby provides a promising scope for further research of this novel metal coating for use in the biomedical sectors, specifically for dental implants.

Assessing the role of friction stir welding tool shoulder profile and parameters on mechanical performance of Al5083 weld joints pre- and post-corrosion exposure

Al5083 alloy sheets were joined by friction stir welding (FSW) by using three different tools having different shoulder profiles (flat, concave and convex) at three different tool rotational speeds. From the cross-sectional microstructures, weld joints obtained at 1120 rpm with three different shoulder profiles were observed as defect free. XRD analysis confirms the development of texture that was dominated with close packed planes. The weld joint mechanical performance was assessed by conducting tensile tests before and after exposing them to 3.5% NaCl solution for 24 h. Combination of concave shoulder profile with 1120 rpm tool rotational speed has given higher strength in the weld joint, compared with base alloy and the other weld joints. The weld joints produced by using flat and concave shoulder profiles exhibited higher mechanical strength even after corrosion attack compared with the base alloy. From the potentiodynamic polarization studies, the three defect free weld joints (processed at 1120 rpm) were measured with lower corrosion current density. The results demonstrate the promising role of FSW to retain the strength against the corrosion initiated mechanical failure of Al5083 alloy by selecting appropriate combination of the shoulder profile and welding parameters.

On the microstructure, texture and electrochemical properties of severely deformed and artificially aged lightweight AA2050 Al–Cu–Li alloy

Lightweight 3rd generation Al–Cu–Li alloy AA2050 was severely deformed via Multi Axial Forging (MAF) at 170 °C followed by artificial aging at 150 °C. Effect of MAF and post MAF aging on microstructure and precipitation was investigated using transmission electron microscopy (TEM). Formation of deformation bands and large dislocation cells were evident on MAF processed samples. Post MAF peak aging resulted in the distribution of fine T1 precipitates in grain interiors with reduction in grain boundary precipitation. Bulk texture studies reveal the formation of strong Goss and S texture components upon MAF processing. Further, low temperature artificial aging doesn’t exhibit significant changes in texture characteristics, either in terms of texture intensities or texture components. Polarization studies showed that peak aged samples exhibited better corrosion resistance compared to un-aged samples. Overall, 12 pass MAF processed and peak aged samples showed higher corrosion resistance. Further, corrosion surface morphologies examination revealed the change in corrosion mechanisms with thermomechanical treatments. Improved corrosion resistance after MAF and peak aging widens the requirements in aerospace and aircraft applications for such engineering alloys.

Microwave Assisted Synthesis of PtxRu1−x-NiTiO3: A Novel Hybrid Nanostructured Electrocatalyst for Direct Methanol Oxidation

In the present investigation, we have explored the preparation of PtxRu1-x-NiTiO3 hybrid electrocatalysts for the application of methanol oxidization. The XRD and Raman analysis of PtxRu1-x-NiTiO3 confirmed the rhombohedral crystal structure of NiTiO3 and cubic-structured Pt(Ru) nanoparticles. TEM analysis signifies that Pt(Ru) nanoparticles is decorated on the surface of the NiTiO3. The mean size of the Pt(Ru) nanoparticles calculated from the TEM profile is around 2 nm which corroborates with the crystallite size estimated from XRD. The XPS analysis confirms the presence of metallic Pt along with its oxidized components (Pt2+ and Pt4+). The cyclic voltammetry analysis evidence that Pt0.5Ru0.5-NiTiO3 has shown better activity in methanol oxidation compared with the other compositions of PtxRu1−x-NiTiO3 along with the maximum current density of 65.41 mA cm−2 with less carbon poisoning. Chronoamperometry and polarization studies represent the stability and electrochemical activity of the Pt0.5Ru0.5-NiTiO3 electrocatalysts towards methanol oxidation. Based on the research carried out in this work, it is concluded that the PtxRu1−x-NiTiO3 would be a promising candidate as an electrocatalyst for methanol oxidation in direct methanol fuel cells.

Corrosion inhibition of mild steel in acidic environments: Mechanistic insights and protective effects of azo-cum inhibitor

An examination was conducted on a newly developed compound named N1-(coumarin-7-yl) amidrazone (Azo-Cum) to assess its impact on the corrosion of mild steel (MS) in a 1 M hydrochloric acid (HCl) solution. Various analytical techniques, including weight loss, potentiodynamic polarization (PDP), impedance spectroscopy (EIS), cyclic voltammetry (CV), UV–visible spectroscopy, scanning electron microscopy (SEM), and AFM, were employed to evaluate the inhibitory efficiency of the compound. The findings indicated that inhibition efficiency rose with higher concentrations but decreased with elevated temperatures. According to weight loss analysis, the optimal concentration of the new eco-friendly inhibitor (5 ×10−4 M) exhibited a maximum efficiency of 89.26%. Polarization studies disclosed that Azo-Cum acted as a mixed-type inhibitor with a cathodic predominance. The adsorption of the inhibitor on the MS surface followed the Langmuir adsorption isotherm. Additionally, the study explored the synergistic effect of Azo-Cum in combination with KI on MS corrosion in a 1 M HCl (Blank) solution using potentiodynamic polarization measurements. The results identified concentration ranges that demonstrated antagonistic inhibition. Density functional theory (DFT) and molecular dynamic simulation (MD) calculations were performed to investigate the correlation between molecular and chemical reactivity.

Novel TiO2 nanoparticle-based sensor for xanthate quantification in mineral flotation samples

A voltammetric method for xanthate quantification was developed by fabricating a new electrode based on TiO2 nanoparticles (TiO2 NPs). The nanomaterial in the anatase phase was synthesized by a simple sol-gel method followed by a thermal treatment (9 h at 500 °C). The nanoparticles have a spheroidal morphology with an average size of 20.61 ± 6.01 nm. The band gap energy (3.7 eV) was determined by means of UV–visible spectroscopy from the absorption band at 335 nm. The TiO2 based sensor was employed as working electrode (electroactive area: 0.02248 cm2) in a cyclic voltammetry study, and a greater peak current was observed for the electrooxidation of isopropyl xanthate at pH 10 as compared to the unmodified electrode. The electrode optimization showed that the percentage of TiO2 and the amount of mineral oil in the electrode have a significant influence on the electrochemical response, with 18.4 % of TiO2 NPs, 0.74 mL of mineral oil, and 18 h of electrode rest before the first use as optimal conditions. In the polarization studies, the charge transfer reaction occurred through a lower overpotential with respect to the open circuit potential. The exchange current density was three times higher for the modified electrode. Electrochemical impedance spectroscopy indicated the detection of xanthate with lower charge transfer resistance than when the unmodified electrode was used. The electrochemical sensor allows the quantification of xanthate from 5 μmol/L to 10 mmol/L by cyclic voltammetry and the square wave technique. For the cyclic voltammetry calibration, the limits of detection and quantification were 40.6 μmol/L and 135 μmol/L, respectively. The limit of detection by square wave voltammetry was 2.4 μmol/L, and the limit of quantification was 7.9 μmol/L. The repeatability of the method showed a relative dispersion of 3.1 % at 0.51 mmol/L. The electroanalytical response of the sensor was reproducible up to 30 days. The recoveries of xanthate in real flotation samples were 91.9 % and 94.6 % for concentrations of 0.55 and 1.1 mmol/L, respectively. No statistically significant differences were found between the quantification using the sensor and the UV spectrophotometric method. Dicresyl dithiophosphate showed statistically significant interference with the xanthate oxidation signal.

Eco-friendly spark-generated CoxOy nanoparticle-modified graphite screen-printed sensing surfaces for the determination of H2O2 in energy drinks

The modification of graphite screen-printed electrodes (SPEs) is reported using an eco-friendly and extremely fast method based on the direct cobalt pin electrode-to-SPE spark discharge at ambient conditions. This approach does not utilize any liquids or chemical templates, does not produce any waste, and allows the in-situ generation of CoxOy nanoparticles onto the electrode surface and the development of efficient electrocatalytic sensing surfaces for the determination of H2O2. Co-spark SPEs were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy and x-ray photoelectron spectroscopy (XPS), revealing the formation of surface confined CoxOy nanoparticles and the diverse oxidation states of cobalt species. Co-spark SPEs were also characterized with cyclic voltammetry and electrochemical impedance spectroscopy. Redox transitions of the surface confined electrocatalysts are demonstrated by electrochemical polarization studies, showing the formation of different oxides (CoxOy), varying the XPS results. Amperometric measurements at 0.3 V vs. Ag/AgCl revealed a linear relationship between the current response and the concentration of H2O2 over the range 1 − 102 μM, achieving a limit of detection (3σ/m) of 0.6 μM. The interference effect of various electroactive species was effectively addressed by employing dual measurements in the absence and presence of the enzyme catalase. The analytical utility of the method was evaluated in antioxidant rich real-world samples, such as energy drinks, demonstrating sufficient recovery.Graphical

Synthesis and investigation of two new compounds (2-(methoxymethyl)−1- phenyl-2-propen-1-one and 2-(methoxymethyl)−1-(4-methoxyphenyl) - 2-Propen-1-one) as corrosion inhibitors for mild steel in acidic solutions at elevated temperature.

This study evaluated the performance of two newly synthesized organic corrosion inhibitors using the gravimetric weight loss method in hydrochloric acid (HCl), methanesulphonic acid (MSA), and a combination of HCl and MSA in the presence of different corrosion inhibitor (CI) concentrations at temperatures of 30 °C to 90 °C. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies were carried out for an in-depth study of corrosion mechanisms. Following the weight loss study, the percentage inhibition efficacies of C1 and C2 at 300 ppm concentrations were found to be ≈ 100% at 30 °C, 40 °C and 60 °C in 15 wt% HCl, 10 wt% MSA, and a combination of both acids (15 wt% HCl and 10 wt% MSA). The performances of C1 and C2 deteriorated slightly when tested in 10 wt% MSA at 90 °C. The synthesized CIs still showed a very high inhibition efficiency in the presence of 15 wt% HCl and a mixture of acids (HCl and MSA) at 90 °C. PDP studies indicated that both C1 and C2 act as anodic inhibitors. The inhibition efficiencies obtained from the PDP and EIS studies agreed with the weight loss study. The high value of Kads and the negative ∆Gads value suggests that C1 and C2 corrosion inhibitors have a strong and spontaneous tendency to chemisorb onto the mild steel surface. SEM-EDX studies proved the formation of a uniform, protective corrosion inhibitor film on the metal surface. Both C1 and C2 have been proven suitable for high-temperature corrosion applications.

Recent Indian contribution in the realms of polar studies

Recent Indian contribution in the realms of polar studies

Synthesis of Silane Functionalized LDH-Modified Nanopowders to Improve Compatibility and Enhance Corrosion Protection for Epoxy Coatings.

Novel modified Zn-Al LDH/epoxy coatings are synthesized and applied to steel substrates, providing active corrosion protection and improved barrier properties. This protective coating is made by combining Epon 828 as a polymer matrix with modified layered-double-hydroxy (LDH) nanoparticles acting as corrosion inhibitor containers. To synthesize the coatings, nitrate was intercalated into Zn-Al-LDH layers through an aqueous co-precipitation method to obtain Zn-Al LDH-NO3, and decavanadate replaced nitrate within the LDH layers through an anion exchange process to obtain Zn-Al LDH-(V10O28)6-. The intercalated LDH was functionalized by silanization with (3-aminopropyl)triethoxysilane (APTES) to increase the compatibility of the LDH inhibitor nanocontainers with epoxy resin and produce a protective coating. To protect the mild steel substrate, functionalized LDH nanopowders were dispersed into the epoxy resin, mixed with a polyamide hardener (Epikure 3571), and applied and cured to the metal surface. Surface morphology, structure, and chemical composition were determined for the modified LDH nanopowders using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Corrosion protection of the coating system was studied using long-term immersion testing and potentiodynamic polarization studies in a 3.5 wt.% NaCl solution.

Conceptual basis for studying the fungal biodiversity in organogenic soils in the area of the Bulgarian Antarctic Base ‘St. Kliment Ohridski’ on Livingston Island

In 2023, a scientific project for studying the fungal biodiversity in organogenic soils in the area of the Bulgarian Antarctic Base ‘St. Kliment Ohridski’ on Livingston Island was funded by the National Center for the Polar Studies at Sofia University ‘St. Kliment Ohridski’, implemented under the National Program for Polar Research ‘From Pole to Pole’, adopted by the Ministry of Education and Science.  In the period February-March 2023, a total of 126 soil samples were collected for analysis. Soil samples were carried out in the upper 0-5 cm soil layer. In places with deeper soil profiles, samples were collected from the deeper layer >5 cm. All samples were stored in sterile polyethylene bags in a freezer at minus 28°C on the Bulgarian ship ‘St. St. Cyril and Methodius’, which arrived in Bulgaria on 2nd May 2023. The present study aims to present the conceptual basis for the study of structure, composition, and bioecological features of fungal species occurring in Antarctic organogenic soils from Livingston Island, to investigate the representatives of separate taxonomic groups of invertebrate organisms interacting with the fungal species in the soil, and to establish the relationships with the soil characteristics in the studied sites. Studies of the biological and ecological features of representatives of the mycota in Antarctic organogenic soils, their physiological and biochemical behavior, and interaction with invertebrate organisms, are essential for a better understanding of the biological processes occurring in them, and the implementation of this project will have substantial contribution to these issues.

Study of polarization for even-denominator fractional quantum Hall states in SU(4) Graphene

Abstract We have focused on studying the even-denominator fractional quantum Hall (EDFQH) states observed in monolayer graphene. In this article, we have studied polarization mainly for the two EDFQH states at filling fractions ν = 1/2, 1/4, which are observed in an experimental study [Nat. Phys. 14, 930 (2018)] a few years ago. We have applied Chern-Simon’s gauge field theory to explain the possible variational wave functions for different polarized states and calculated their ground state energies using the Coulomb potential. We have chosen the lowest energy states using suitable combinations of attached flux quanta to the electrons for different polarized states of those EDFQH states.

Experimental Studies on the Effect of Expired Amiodarone Drug (EAD) as a Corrosion Inhibitor on Mild Steel in 1 M HCl.

In the present investigation, the corrosion tendency of mild steel under acidic pH was studied by employing unused expired amiodarone (EAD) drug as a potential corrosion inhibitor by adopting the weight loss measurement method. The corrosion inhibition efficiency (IE) of the formed protective film (EAD) on the steel surface was analyzed using potentiodynamic polarization and AC-impedance spectroscopy studies. The surface morphology of the mild steel before and after corrosion (in 1.0 M HCl) was analyzed via scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDAX), atomic force microscopy (AFM), and thermodynamic studies. The weight loss measurement under different concentrations of EAD indicated that an excellent inhibition was displayed at a concentration of 0.001 M, and the IE was found to depend on both the concentration and molecular structure of EAD. A potentiodynamic polarization study revealed that EAD predominantly acted as a cathode inhibitor, and electrochemical impedance spectroscopy (EIS) confirmed the adsorption of EAD on the surface of mild steel, which obeyed Temkin's adsorption isotherm model. The calculated thermodynamic parameters revealed that adsorption was spontaneous and exothermic.

Inhibitory effects of 1-butylpyridin-1-ium bromide in 0.1 M sulphamic acid for mild steel

ABSTRACT In recent years, there has been a consistent development in the introduction of novel corrosion inhibitors due to their potential to reduce the dissolution of metal surfaces under various corrosive environments. The current study investigates the inhibitory effect of the surfactant 1-butylpyridin-1-ium bromide (BPB) on mild steel (MS) in 0.1 M sulphamic acid. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) studies were used to analyse the inhibition investigations. In addition, atomic force microscopy (AFM), scanning electron microscopy (SEM) and contact angle (CA) measurements were also used to analyse the inhibition investigations. The PDP studies showed a maximum inhibition efficiency of 63.3% at 400 ppm concentration, demonstrating the inhibitor’s efficacy. The investigated compound was found to comply with the Temkin adsorption isotherm with an R 2 value of 0.99954. The results of PDP tests firmly suggest that the inhibitor is of mixed type. ΔG ads values of −9.659 kJ mol−1 suggested that the inhibitor adhered to the metal surface by physical adsorption. Based on the findings it appears that the molecules adhere to the surface of MS forming partial hydrophobic films that act as a barrier for the metal surface.

Mechanism of electrochemical carbon dioxide reduction to formate on tin electrode

Carbon dioxide can be electrochemically reduced to formate on tin electrodes. Formate is one of the most economically viable products of CO2 reduction reaction (CO2RR). While CO2 is reduced to formate, hydrogen evolution reaction (HER) occurs concomitantly. The kinetics of CO2RR and HER on the tin electrode was investigated. Potentiodynamic polarization studies were conducted in CO2 saturated and N2 saturated 0.1 M KHCO3 solutions, in the potential range from −0.014 V to −1.59 V vs. RHE. A faradaic efficiency of 93.95 % towards formate production was obtained at −1.09 V vs. RHE. The mass transfer effects and bicarbonate dissociation equilibrium were used to estimate the concentration of the reactants at the electrode surface. Density functional theory calculations indicate that –OCHO intermediate species is thermodynamically favoured, and a four-step reaction with two intermediates is proposed. The proposed mechanism captures the major features of the polarization data. CO2 reduction occurs via two intermediate species, viz. adsorbed H and OCHO species, while HER occurs via Volmer-Heyrovsky steps. The model predicts that in N2 saturated solutions, the fractional surface coverage of adsorbed H reaches a maximum of ∼0.48 at a potential of −0.82 V vs. RHE while in CO2 saturated solutions, the corresponding value is ∼0.29. In addition, the maximum fractional surface coverage of adsorbed OCHO is predicted to be ∼0.12 in CO2 saturated solutions.

Thermal transport and optical anisotropy in CVD grown large area few-layer MoS2 over an FTO substrate

Atomically thin MoS2 is a promising candidate for its integration into devices due to its strikingly unique electronic, optical, and thermal properties. Here, we report the fabrication of a few-layer MoS2 thin film over a conducting fluorine-doped tin oxide-coated glass substrate via a one-step chemical vapor deposition method. We have quantitatively analyzed the nonlinear temperature-dependent Raman shift using a physical model that includes thermal expansion and three- and four-phonon anharmonic effects, which exhibits that the main origin of nonlinearity in both the phonon modes primarily arises from the three-phonon anharmonic process. We have also measured the interfacial thermal conductance (g) and thermal conductivity (ks) of the synthesized film using the optothermal Raman spectroscopy technique. The obtained values of g and ks are ∼7.218 ± 0.023 MW m−2 K−1 and ∼40 ± 2 W m−1 K−1, respectively, suggesting the suitability of thermal dissipation in MoS2 based electronic and optoelectronic devices. Furthermore, we performed a polarization study using the angle resolved polarized Raman spectroscopy technique under non-resonance and resonance excitations to reveal the electron–photon–phonon interaction in the prepared MoS2, based on the semi-classical theory that includes deformation potential and Fröhlich interaction. Our study provides much needed experimental information about thermal conductivity and polarization response in a few-layer MoS2 grown over the conducting substrate, which is relevant for applications in low power thermoelectric and optoelectronic devices.

Kimura's contributions on Earth polar motion studies.

Kimura's discovery of z-term in the polar motion (Astron. J. 22, 107 (1902) and Astron. Nachr. 158, 233 (1902)) was recognized as an epoch-making scientific achievement for modern Japan, opening its doors to the world in 1868. Although Kimura served as the chair of the International Latitude Service during 1922-1934 and made efforts to interpret the z-term, it was unsuccessful. The physical interpretation of the z-term was given decades later by Wako (PASJ, 22, 525 (1970)). This article highlights Kimura's additional contributions that led to the interpretation by Wako.

Effect of the ketone beta-hydroxybutyrate on markers of inflammation and immune function in adults with type 2 diabetes.

Pre-clinical and cell culture evidence supports the role of the ketone beta-hydroxybutyrate (BHB) as an immunomodulatory molecule that may inhibit inflammatory signalling involved in several chronic diseases such as type 2 diabetes (T2D), but studies in humans are lacking. Therefore, we investigated the anti-inflammatory effect of BHB in humans across three clinical trials. To investigate if BHB suppressed pro-inflammatory cytokine secretion, we treated LPS-stimulated leukocytes from overnight-fasted adults at risk for T2D with BHB (Study 1). Next (Study 2), we investigated if exogenously raising BHB acutely in vivo by ketone monoester supplementation (KME) in adults with T2D would suppress pro-inflammatory plasma cytokines. In Study 3, we investigated the effect of BHB on inflammation via ex vivo treatment of LPS-stimulated leukocytes with BHB and in vivo thrice-daily pre-meal KME for 14 days in adults with T2D. Ex vivo treatment with BHB suppressed LPS-stimulated IL-1β, TNF-α, and IL-6 secretion and increased IL-1RA and IL-10 (Study 1). Plasma IL-10 increased by 90 min following ingestion of a single dose of KME in T2D, which corresponded to peak blood BHB (Study 2). Finally, 14 days of thrice-daily KME ingestion did not significantly alter plasma cytokines or leukocyte subsets including monocyte and T-cell polarization (Study 3). However, direct treatment of leukocytes with BHB modulated TNF-α, IL-1β, IFN-γ, and MCP-1 secretion in a time- and glucose-dependent manner (Study 3). Therefore, BHB appears to be anti-inflammatory in T2D, but this effect is transient and is modulated by the presence of disease, glycaemia, and exposure time.

Polarization and single-pulse micro-structure studies of Rotating Radio Transient J0139+3336 with FAST

ABSTRACT The study of polarization and micro-structure is very important for understanding the radiation mechanism of Rotating Radio Transients (RRATs). Due to the limitations of telescope sensitivity and time resolution, studies of the polarization and micro-structure of RRATs have been rare in the past. In this work, we report on a high-time resolution and full polarization observation of RRAT J0139+3336 with the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). A total of 96 burst pulses were detected in the 3-h observation. The degrees of linear and circular polarization and the shape of the polarization position angle (PPA) of the single pulses vary significantly. The average profile displays a small degree of linear and circular polarization, and the PPA exhibits a remarkably smooth and steep S-shaped curve, which are also characteristics of pulsars. The circular polarization in some single pulses demonstrates a clear sign change. We discuss the geometric structure of the emission beam based on the results from fitting the RVM model to the changes in the PPA. Using an autocorrelation analysis, the quasi-periodic micro-structure in the single pulse emission is detected with a median period of about 0.91 ms. We show that the position of RRAT J0139+3336 on the P–Pμ diagram falls in the normal pulsar (NP) region . The radio emission of RRAT J0139+3336 shows unique properties, such as the sign change in the circular polarization and quasi-periodicity in the micro-structure, which will provide important clues to the emission mechanism of RRATs.

Exploring limitations in the induced polarization versus surface conductivity relationship in the case of wetland soils

Recent induced polarization studies suggest that the real part of surface conductivity ([Formula: see text]) scales linearly with the imaginary conductivity ([Formula: see text] = [Formula: see text]) or normalized chargeability (Mn) for a range of soil types. The coefficients of this relationship l and l_Mn ( l = [Formula: see text]/[Formula: see text] or l_Mn = Mn/[Formula: see text]) allow the separation of the surface and electrolytic conductivities from the bulk conductivity. However, the dependence of these constants on varying soil physicochemical properties, including under unsaturated conditions, is yet to be assessed. Using estimates of [Formula: see text] from 18 undisturbed soil samples from a restored wetland and [Formula: see text] measured over a frequency range of 0.01 Hz to 10 kHz, the [Formula: see text] and [Formula: see text] were compared with the laboratory measurements of soil properties. Also, l and l_Mn were calculated for each soil sample and regressed them against the soil properties. We find an apparent dependence of l on soil texture, bulk density, organic matter, and moisture contents, with coefficients of determination ([Formula: see text]) ranging from 0.5 to 0.65 at low frequencies (e.g., 1 Hz) but not at high frequencies (e.g., 936 Hz). This dependence of l on soil texture results from the insensitivity of [Formula: see text] at low frequency to [Formula: see text] and, by implication, to the soil properties controlling [Formula: see text]. In contrast, l_Mn indicates no correlation with the soil properties because Mn is linearly correlated with [Formula: see text] and correlated with the soil properties controlling [Formula: see text]. Our results call for caution on the application of [Formula: see text] at a single frequency as a proxy of [Formula: see text] because [Formula: see text] is not necessarily correlated with [Formula: see text] across all soil types. Although using l_Mn derived from multifrequency measurements overcomes this limitation, field acquisition of spectral information (e.g., up to 1000 Hz) remains a challenge.