Electrical Resistivity Measurements Research Articles

A unit series–parallel unsaturated soil electrical conductivity model considering interconnections between pores

For the potential application of electrical resistivity measurements in hydrogeological investigations, the knowledge of soil electrical conductivity mechanism with moisture content variation is the key issue. The impact of interconnections between pores and weak connection to physical processes were the two limitations for unsaturated soil electrical conductivity research. In this work, we introduced the concept of equivalent conductive pathway to analyze tortuosity. Based on media series–parallel analysis, a unit series–parallel unsaturated soil electrical conductivity model considering interconnections between pores was established, in which parameters with its own physical meaning. To verify the accuracy of the proposed model, soil resistivity test with moisture content variation was conducted. Soil electrical conductivity was predicted, which was compared with results from test and previous models. The results indicate that our model is expected to produce better results than the previous models. Overcoming the limitations of weak connection to physical processes in the empirical model, the error of soil resistivity was significantly reduced when the impact of interconnections between pores was considered. The average error of the proposed model for clay and sand was 30.6% and 17.4%, respectively, compared to 72.6% and 48.2% for the model that ignored the interconnections between pores. The findings of this study could provide a reference for hydrogeological investigations, such as levee leakage detection.

Calibrating electrical resistivity measurements in reinforced concrete with rebar effects and practical guidelines

Calibrating electrical resistivity measurements in reinforced concrete with rebar effects and practical guidelines

Pressurised water flow in fractured permafrost rocks revealed by borehole temperature, electrical resistivity tomography, and piezometric pressure

Abstract. Rock slope instabilities and failures from permafrost rocks are among the most significant alpine hazards in a changing climate and represent considerable threats to high-alpine infrastructure. While permafrost degradation is commonly attributed to rising air temperature and slow thermal heat propagation in rocks, the profound impact of water flow in bedrock permafrost on warming processes is increasingly recognised. However, quantifying the role of water flow remains challenging, primarily due to the complexities associated with direct observation and the transient nature of water dynamics in rock slope systems. To overcome the lack of a quantitative assessment, we combine datasets of rock temperature measured in two deep boreholes (2016–2023), with electrical resistivity tomography measurements repeated monthly in 2013 and 2023; the site-specific temperature–resistivity relation determined in the laboratory with samples from the study area; and borehole piezometer data. Field measurements were carried out at the permafrost-affected north flank of the Kitzsteinhorn (Hohe Tauern range, Austria), which is characterised by significant water outflow from open fractures during the melt season. Borehole temperature data demonstrate a seasonal maximum of the permafrost active layer of 4–5 m. They further show abrupt temperature changes (∼ 0.2–0.7 °C) at 2, 3, and 5 m depth during periods with enhanced water flow and temperature regime changes between 2016–2019 and 2020–2022 at 10 and 15 m depth, which cannot be explained solely by conductive heat transfer. Electrical resistivity measurements repeated monthly reveal a massive decrease in resistivity from June to July and the initiation of a low-resistivity (< 4 kΩ m) zone in the lower part of the rock slope in June, gradually expanding to higher rock slope sections until September. We hypothesise that the reduction in electrical resistivity of more than an order of magnitude, which coincides with abrupt changes in borehole temperature and periods of high water heads up to 11.8 m, provides certain evidence of snowmelt water infiltration into the rockwall becoming pressurised within a widespread fracture network during the thawing season. This study shows that, in addition to slow thermal heat conduction, permafrost rocks are subjected to sudden push-like warming events and long-lasting rock temperature regime changes, favouring accelerated bottom-up permafrost degradation and contributing to the build-up of hydrostatic pressure, potentially leading to slope instability.

New Layered Boride NiPtB2-x (x = 0.5) with a Ternary Derivative Structure of MoB.

A novel ternary boride, NiPtB2-x (x = 0.5), was obtained by argon-arc melting of the elements followed by annealing at 750 °C. It exhibits a new structure type with the space group Imma (a = 2.9835(3) Å, b = 3.0470(3) Å, c = 15.3843(3) Å; Z = 4; single-crystal X-ray data) and displays distinct layers of condensed [BNi6] and [BPt6] (and [Pt6]) trigonal prisms with mutually perpendicular axes. Atoms of Pt and Ni from adjacent layers interlink to form empty tetragonal pyramids and tetrahedra. Two boron atom positions form two orthogonal zigzag chains; however, one boron position exhibits a partial boron occupancy. Considering B-deficiency, the platinum boride substructure in NiPtB2-x quantitatively corresponds to a trigonal prismatic slab in the Pt2B structure, while the nickel boride partial structure is consistent with the CrB-type NiB binary. Cell parameters and atomic coordinates of NiPtB2-x and Pt2B were refined in the scope of generalized gradient approximation. Chemical bonding analysis by means of the electron localizability approach, supported by Bader charge analysis, reveals a strong electron contribution of Ni atoms for stabilization of the boron zigzag chains, wherein boron atoms are bonded covalently. Bonding within the platinum boride partial structures in the studied compounds varies depending on the atom coordination of boron: from covalent in both the NiPtB2-x structure and trigonal prismatic slabs in Pt2B to mixed metallic with covalent contributions in [BPt6] octahedra in Pt2B. Electrical resistivity measurements characterize NiPtB2-x as a metal with no phase transitions in the temperature range from 2 to 300 K, in concord with electronic band structure calculations and specific heat measurements. The compound is characterized by a positive Hall coefficient at 20 K. This work unveils a new elemental space on realizing novel layered boride structural arrangements and provides a reference for future experiments.

Effects of Electron, Gamma and Neutron Irradiation on the Superconducting Properties of (Bi,Pb)2Sr2Ca2Cu3Ox Bulk Samples

In this study, we explored the potential of irradiation techniques to optimize defect concentration and crystal structure in (Bi,Pb)₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) superconductors, aiming to enhance their practicality by potentially improving their critical temperature (Tc) in high magnetic fields. Bi-2223 superconductors have higher Tc and less stringent cooling requirements than low-temperature types, yet enhancing Tc under high magnetic fields is still challenging. The study meticulously compared the electrical properties of Bi-2223 samples in bulk form, subjected individually to electron, gamma, and neutron irradiations, prepared via the conventional solid-state reaction method. Subsequent analyses of structural properties through X-ray diffraction revealed changes in cell lattice parameters, while electrical resistance and AC susceptibility measurements provided insights into the critical temperature. Interestingly, a significant decrease in Tc was observed across all irradiated samples instead of an enhancement, challenging our initial hypothesis. Electron and gamma irradiations led to more homogeneously distributed and less porous defects compared to neutron irradiation, which correlated with the observed decrease in Tc—22.9% for neutron, 16.7% for gamma, and 13.5% for electron irradiation. These results highlight the intricate relationship between the type and distribution of defects induced by different irradiations and their varying impacts on superconductor performance. This study illustrates how defects, based on their characteristics, distinctly affect superconducting properties, emphasizing the complexity of defect interactions in superconductors. Our findings highlight the crucial relationship between irradiation-induced defects and the superconducting properties of Bi-2223, suggesting that the impact of Tc reduction on high-temperature superconductor applications needs to be reevaluated.

P0132 ACSS2 inhibition alleviates inflammatory signaling and improves epithelial integrity in Inflammatory Bowel Disease in vitro models

Abstract Background Inflammatory bowel disease (IBD), encompassing Ulcerative Colitis (UC) and Crohn’s Disease (CD), is marked by chronic gastrointestinal inflammation stemming from genetic, environmental, immunological, and microbiota factors1. Acetyl-CoA Synthetase Short Chain Family Member 2 (ACSS2) converts acetate into acetyl-CoA and is primarily cytosolic, but translocates to the nucleus under metabolic stress, where it regulates gene transcription and cellular processes2. Although the gastrointestinal microbiota influences acetate levels, the role of ACSS2 in colitis and intestinal inflammation remains poorly understood3. Methods To evaluate ACSS2's role in IBD, we employed in vitro IBD models using Caco-2 and HT-29 intestinal epithelial cell lines. ACSS2 activity was inhibited with an ACSS2 inhibitor, followed by inflammatory stimulation with 100 ng/ml Tumor Necrosis Factor-α (TNF-α) for 30 minutes or 1% Dextran Sodium Sulfate (DSS) for 6 hours. Protein expression levels were assessed via Western blot and immunohistochemistry (IHC) on paraffin-embedded samples from UC patients. The effects of ACSS2 inhibition on inflammatory signaling pathways and cell integrity were assessed using RT-qPCR, immunoblotting, and transepithelial electrical resistance (TEER) measurements. Results Treatment of Caco-2 and HT-29 cells with DSS or TNF-α induced upregulation of ACSS2 protein levels compared to controls. IHC analysis of 30 paired paraffin-embedded colon samples from UC patients revealed higher ACSS2 expression and nuclear localization in inflamed sections compared to non-inflamed regions. Inhibition of ACSS2 activity in stimulated Caco-2 and HT29 cells led to a significant decrease in the gene expression levels of pro-inflammatory cytokines such as Interleukin 8 (IL-8), IL-1β and TNF-α. Additionally, immunoblotting demonstrated reduced phosphorylation of p65 and ERK/MEK, indicating suppression of NF-κB and MAPK inflammatory signaling pathways. To assess the effect of ACSS2 inhibition on cell integrity, TEER assays revealed that ACSS2 inhibition preserved cell integrity in DSS-treated monolayers, accompanied by increased expression of tight junction proteins Occludin and ZO-1, suggesting improved epithelial integrity in the inflammatory context. Conclusion Our findings demonstrate a pro-inflammatory role for ACSS2 in IBD, mediated through its involvement in inflammatory signaling and epithelial integrity. These results highlight ACSS2 as a potential therapeutic target for IBD and warrant further investigations in more advanced models, including human-derived intestinal organoids and in vivo systems, to validate its role in disease pathogenesis and therapeutic potential.

P0054 Human colonoid-derived monolayers and Caco-2: comparative analysis of inflammatory responses

Abstract Background Given the increasing incidence of inflammatory bowel diseases, there is a growing need for reliable preclinical models that replicate the inflamed intestinal epithelium. Immortalized Caco-2 cells are widely considered the standard in vitro model for intestinal studies, but human-derived colonoid monolayers (CDMs) could be proposed as a powerful alternative to more accurately mimic the pathophysiological features of intestinal inflammation. The present study aims to compare the functional and morphological responses induced by inflammatory cytokines TNFα and IFNγ on CDMs and Caco-2. Methods Human colonic crypts from biopsies of 5 healthy volunteers were embedded in Matrigel® and cultured for 5-7 days. IntestiCult™ OGM was used to expand cystic-like colonoids, and single cells were seeded onto coated 24-well inserts. Upon reaching confluence, the medium was switched to IntestiCult™ ODM. Caco-2 cells were cultured for 21 days on 24-well inserts. Differentiated CDMs and Caco-2 monolayers were exposed to 25 ng/mL TNFα-IFNγ for 24 hours. Cell differentiation was assessed by immunocytochemistry (ICC), and barrier integrity was evaluated by transepithelial electrical resistance (TEER) measurement. Cytotoxicity was assessed through the LDH assay. IL-8 and CCL20 release were quantified. Results Both models showed increasing TEER over the growth period, indicating the gradual development of epithelial barriers, up to 484±58 Ω*cm2 for CDMs and 700±184 Ω*cm2 for Caco-2. ICC staining for epithelial markers villin and MUC2 confirmed polarization and differentiation under basal conditions in both models, cytokines reduced the expression of epithelial markers. Inflammation reduced the barrier integrity of the monolayers (approximately 18%), although more uniformly in Caco-2 than in CDMs. IL-8 and CCL20 release was augmented by cytokines in both models, (for IL-8 of about 20 times in CDM and 2 times in Caco-2). As regards cell viability, CDMs (40% cytotoxicity) showed higher sensitivity to cytokines than Caco-2 (22% cytotoxicity). Conclusion Exposure to an inflammatory environment altered cell morphology and impaired epithelial barrier integrity in both CDMs and Caco-2 monolayers. These findings highlight the potential of CDMs as an advanced model for studying personalized responses in intestinal inflammation.

Evaluation of Frequency Effects on Fatigue Life at High Test Frequencies for SAE 1045 Steel Based on Thermography and Electrical Resistance Measurements

Evaluation of Frequency Effects on Fatigue Life at High Test Frequencies for SAE 1045 Steel Based on Thermography and Electrical Resistance Measurements

Impedance mapping with high-density microelectrode array chips reveals dynamic heterogeneity of in vitro epithelial barriers

Epithelial tissues in vitro undergo dynamic changes while differentiating heterogeneously on the culture substrate. This gives rise to diverse cellular arrangements which are undistinguished by conventional analysis approaches, such as transepithelial electrical resistance measurement or permeability assays. In this context, solid substrate-based systems with integrated electrodes and electrochemical impedance monitoring capability can address the limited spatiotemporal resolution of traditional porous membrane-based methods. This label-free technique facilitates local, continuous, long-term analysis of tissue barrier properties for organ-on-chip applications. Increasing spatial resolution requires small electrodes arranged in a dense array, known as high-density microelectrode arrays (HD-MEAs). Integrated with Complementary Metal Oxide Semiconductor (CMOS) technology for multiplexing and rapid impedance measurements, HD-MEAs can enable high spatiotemporal resolution assessments of epithelial tissues. Here, we used 16,384 CMOS-integrated HD-MEA chip with subcellular-sized electrodes (8 μm diameter, 15 μm pitch, patterned in 16 clusters each consisting of 1024 electrodes in a 32 × 32 matrix) and impedance sensing capability to monitor dynamic evolution of Caco-2 cells, such as their proliferation, barrier formation, and 3D structure development on the chip. Changes in impedance at the selected frequency of 1 kHz (|Z|1kHz) enabled monitoring and analyzing the life cycle of Caco-2 cells grown on the HD-MEA chips (up to + 453% change after 7 days in culture). The |Z|1kHz maps of proliferating Caco-2 cells and the differentiating epithelial tissue developing 3D domes aligned with the corresponding optical images at cellular resolution, which demonstrates the capability of the chip in tracking the dynamic heterogeneity of Caco-2 tissues in a label free and real-time fashion. Importantly, |Z|1kHz maps acquired during chemically induced barrier disruption showed electrodes covered with 3D cell domes experienced a stronger decrease in impedance than those covered with adherent cells (-41% ± sd 10% against -16% ± sd 10%, respectively). This method could thus, in principle, enable detection of tissue barrier disrupting and modifying agents with higher specificity. Epithelial barrier function assays benefit from using HD-MEA impedance sensors due to their increased informativity and resolution, which will be of great value in future organ-on-chip platforms.

Non-invasive in vitro NAM for the detection of reversible and irreversible eye damage after chemical exposure for GHS classification purposes (ImAi).

The potential risk of chemicals to the human eye is assessed by adopted test guidelines (TGs) for regulatory purposes to ensure consumer safety. Over the past decade, the Organization for Economic Co-operation and Development (OECD) has approved new approach methodologies (NAMs) to predict chemical eye damage. However, existing NAMs remain associated with limitations: First, no full replacement of the in vivo Draize eye test due to limited predictability of severe/mild damage was reached. Second, the existing NAMs do not allow reliable differentiation between reversible and irreversible eye damage. Especially the prediction of tissue recovery remains challenging in vitro. Existing in vitro NAMs are based on destructive analysis with no consideration of tissue recovery. In this study, we developed a standalone eye-irritation test method based on non-invasive impedance spectroscopy (ImAi) to discriminate between damaging and irritating chemicals. Tissue effects were analyzed via transepithelial electrical resistance (TEER) measurements of human in vitro epithelial models over 14days. The TEER was performed using a developed impedance spectrometer. For development of the EIT, a chemical reference list of 329 chemicals was compiled. The applicability of the ImAi-test was exemplified by the discrimination of Cat. 1 vs. Cat. 2 for 23 reference chemicals. Correct classification was achieved for 90.9% of Cat. 1 and 83.3% of Cat. 2 chemicals. Our non-invasive in vitro test overcomes the limitations of Cat. 2 classification of the existing in vitro methods and provides for the first time a non-animal test method that can fully replace the Draize eye test.

Microscale Electrical Resistivity Measurements to Investigate Particle Distribution.

The functional performance of a particulate thin film depends greatly on the particle distribution that forms during drying. In situ methods for monitoring the impact of different processing parameters on the distribution of particles currently require expensive and specialized equipment. This work addresses this gap by miniaturizing a geophysical prospecting method to thin-film applications. In this method, four-electrode resistivity measurements at variable probe spacing detect changes in the vertical particle concentration profile. A heuristic colloidal drying model describes the particle distribution during drying in terms of the relative effects of Brownian diffusion, sedimentation, and evaporation. For sedimentation- and evaporation-dominated drying, the film is modeled as two stratified layers of different concentrations. Solving this model simultaneously alongside Laplace's equation for electrostatic resistance identifies the parameters necessary to distinguish between diffusion-, sedimentation-, and evaporation-dominated drying. For resistive particles in a conductive solvent, simulations predict that the normalized thickness of the top layer, δt/H0, must exceed a critical value to distinguish between different drying regimes. The heuristic model results are validated theoretically by comparison to a physics-based drying model. Model predictions are experimentally validated by fabricating a custom microlithography four-line probe device and measuring the transient resistance of systems for which the drying mechanism is known. This work offers a low-cost and in situ method to identify drying mechanisms and extract physical parameters that better characterize the processing-structure-function relationships for many coatings.

Lipopolysaccharide-induced active telocyte exosomes alleviate lipopolysaccharide-induced vascular barrier disruption and acute lung injury via the activation of the miRNA-146a-5p/caspase-3 signaling pathway in endothelial cells.

Lipopolysaccharide (LPS)-induced apoptosis of lung microvascular endothelial cells (ECs) is the main reason of lung edema and acute lung injury (ALI) in septic conditions. Telocytes (TCs) are a distinct type of interstitial cells found around the lung microvasculature, which may protect ECs through the release of shed vesicles. However, whether TCs protect against LPS-induced EC apoptosis and ALI has not been determined. The protective effects of TCs on ECs were assessed in vitro using transwell assays and flow cytometry, and in vivo using an LPS-induced mouse ALI model. RNA sequencing was used to identify miRNA-146a-5p as a key component of TC-derived exosomes. The functions of miRNA-146a-5p were further evaluated by western blotting, flow cytometry, and transendothelial electrical resistance measurements. We demonstrated that LPS stimulation induced the secretion of active exosomes from TCs, which inhibited LPS-mediated apoptosis of ECs and reduced ALI in mice. Moreover, miRNA-146a-5p was identified as the main bioactive molecule in TC-derived exosomes, capable of inhibiting LPS-induced caspase-3 activation and apoptosis in ECs. Our results indicate that TCs effectively prevent LPS-induced EC apoptosis and ALI through the release of exosomes, with subsequent activation of the miRNA-146a-5p/caspase-3 signaling pathway in ECs.

Real-time cell barrier monitoring by spatial transepithelial electrical resistance measurement on a microelectrode array integrated Transwell.

Transepithelial electrical resistance (TEER) measurement is a label free, rapid and real-time technique, which is commonly used to evaluate the integrity of cell barriers. TEER characterization is important for applications, such as tissue (brain, intestines, lungs) barrier modeling, drug screening, and cell growth monitoring. Traditional TEER methods usually only show the average impedance of the whole cell layer, and lack accuracy and the characterization of internal spatial differences within cell layer regions. Here, we introduce a new spatial TEER strategy that utilizes microelectrode arrays (MEA) integrated in a Transwell to dynamically monitor TEER. A new electrical model which could reveal spatial impedance non-uniformity was proposed to extract accurate resistance from the measured data. Based on our method, the TEER signals from 16 different regions were successfully monitored in real time. The mapped impedance hotspots in different regions closely correlate with both fluorescence cell staining signals and calculated cell coverage, indicating the effectiveness of the developed spatial TEER system in monitoring local cell growth in vitro. The real-time spatial TEER responses to ethylene glycol-bis(β-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and cisplatin were studied, which could either reduce barrier integrity or inhibit cellular growth. The obtained results demonstrated the spatial TEER's applicability for cell barrier function and cell growth monitoring. Our approach provides accurate spatial electrical information of cell barriers and holds potential applications in drug development and screening.

The influence of annealing temperature on the gas sensing properties of multifunctional hematite (α-Fe2O3) films

In this study, hematite (α-Fe2O3) were prepared using direct solution spin coating and the changes of some physical properties with annealing temperature (400, 500 and 600 °C) for 2 h were investigated. The sensors annealed at 400 °C, 500 °C and 600°C are referred to as F400, F500 and F600 respectively. The X-ray diffraction patterns of the prepared samples confirm the polycrystalline nature of the rhombohedral crystal structure of hematite (α-Fe2O3). The surface roughness parameters (SA-SQ) of the α-Fe2O3 films decreased drastically with increasing annealing temperature from 400 to 600 °C (57.47–68.08/13.63–17.13). The direct optical band gap values were estimated from absorption measurements and ranged from 2.77 to 2.52 eV. The electrical resistivity measurement at room temperature of the samples decreased with increasing annealing temperature from 400 to 600 °C. The response of the CO sensor of F400, F500 and F600 was found at 180 °C. The response to 1 ppm CO gas was calculated to be 1.45%, 8% and 10% for F400, F500 and F600 respectively. The wettability test of the samples showed a water contact angle (WCA) of less than 90°, demonstrating the hydrophilic surface especially for the samples annealed at 500 °C.

Topological electronic structure and transport properties of the distorted rutile-type WO2

We elucidate the transport properties and electronic structures of distorted rutile-type WO2. Electrical resistivity and Hall effect measurements of high-quality single crystals revealed the transport property characteristics of topological materials; these characteristics included an extremely large magnetoresistance of 13 200% (2 K and 9 T) and a very high carrier mobility of 25 700 cm2 V−1 s−1 (5 K). First-principles calculations revealed Dirac nodal lines (DNLs) near the Fermi energy in the electronic structure when spin–orbit interactions (SOIs) were absent. Although these DNLs mostly disappeared in the presence of SOIs, band crossings at high-symmetry points in the reciprocal space existed as Dirac points. Furthermore, DNLs protected by nonsymmorphic symmetry persisted on the ky = π/b plane. The unique transport properties originating from the topological electronic structure of chemically and thermally stable WO2 could represent an opportunity to investigate the potential electronic applications of the material.

Evidence for a metal–bosonic insulator–superconductor transition in compressed sulfur

The abrupt drop of resistance to zero at a critical temperature is a key signature of the current paradigm of the metal-superconductor transition. However, the emergence of an intermediate bosonic insulating state characterized by a resistance peak preceding the onset of the superconducting transition has challenged this traditional understanding. Notably, this phenomenon has been predominantly observed in disordered or chemically doped low-dimensional systems, raising intriguing questions about the generality of the effect and its underlying fundamental physics. Here, we present a systematic experimental study of compressed elemental sulfur, an undoped three-dimensional (3D) high-pressure superconductor, with detailed measurements of electrical resistance as a function of temperature, magnetic field, and current. The anomalous resistance peak observed in this 3D system is interpreted based on an empirical model of a metal-bosonic insulator-superconductor transition, potentially driven by vortex dynamics under magnetic field and energy dissipation processes. These findings offer a fresh platform for theoretical analysis of the decades-long enigmatic of the underlying mechanism of this phenomenon.

In Vitro Evaluation of Intestinal Barrier Function after Exposure to Digested Pea Ingredients─Food Matrix Effect.

Dietary fibers (DF) are important components of human and animal diets. However, they can decrease protein digestibility and absorption and thus the nutritional value of a food. The aim of this study was to investigate how the form of delivery of pea DF impacted the integrity of the intestinal barrier and, thereby, the potential absorption of molecules. To this end, two pea flours, with either intact or ruptured cell walls, and two controls, pea fibers and pea protein, were digested in vitro and the digesta obtained applied onto a jejunum porcine cell line (IPEC-J2 cells). Cell viability and integrity were evaluated by transepithelial electrical resistance measurement, colorimetric assay (MTS), and immunohistochemistry for tight junction proteins. Additionally, the diffusion of FITC-dextran (FD4) and lucifer yellow (LY) through the epithelial cell monolayers was monitored. The digested pea samples did not alter the IPEC-J2 viability and permeability. For instance, no difference in the diffusion of molecules either FD4 or LY across the monolayers was observed between the different digesta and the control. Similarly, no effect was observed in ZO-1 labeling intensity compared to the control. This study demonstrated that intestinal integrity was maintained whether pea cell walls were intact or ruptured.

Semiconductor Transistor-Based Detection of Epithelial-Mesenchymal Transition via Weak Acid-Induced Proton Perturbation.

Developing new detection methods for the epithelial-mesenchymal transition (EMT), where epithelial cells acquire mesenchymal traits, is crucial for understanding tissue development, cancer invasion, and metastasis. Conventional in vitro EMT evaluation methods like permeability measurements are time-consuming and low-throughput, while the transepithelial electrical resistance measurements struggle to differentiate between cell membrane damage and tight junction (TJ) loss and are affected by cell proliferation. In this study, we developed a pH perturbation method to detect TJ barrier disruption during epithelial EMT by sensing proton leakage induced by a weak acid using a pH-responsive semiconductor. Mardin-Darby canine kidney (MDCK) epithelial cell sheets cultured on an ion-sensitive field effect transistor's gate insulator were induced into EMT by exposure to the cytokine transforming growth factor-β1 (TGF-β). Our pH perturbation method successfully detected EMT in MDCK sheets at a TGF-β concentration one-tenth of that required for conventional methods. The high sensitivity and selectivity arise from using minimal protons as indicators of TJ barrier disruption. TGF-β-induced EMT detection results using our method align with EMT-related gene and protein expression data. In drug screening with EMT inhibitors, this novel method showed similar trends to conventional ones. The pH perturbation method enables highly sensitive, real-time EMT detection, contributing to elucidating biological phenomena and pharmaceutical development.

Improvement of the Electrical Properties of ZnO Nanomaterials with Fe by Co-precipitation Method

Fe-doped ZnO nanomaterials were prepared by the co-precipitation method. The experiments used a solution of 0.5 M for ZnCl2, doped with FeSO4 in proportions of 0-100 wt.%, followed by the addition of 1 M for NaOH solution until a pH of 12 was reached. Next, the precipitated substances were calcinated at 550ºC for 3 h in air. SEM image analysis showed that the nanoparticles formed in the condition of pure ZnO and Fe2O3 whereas rod-shaped formed with Fe doping. Nanoparticles of ZnO transformed into nanorods when doped with Fe. EDS analysis detected Fe under the conditions of 3 and 5 wt.% doping. XRD patterns of ZnO and all doping of Fe in ZnO nanostructures were corresponded to a hexagonal wurtzite structure of ZnO which showed crystallite size in the range of 25-29 nm. The electrical properties of Fe-doped ZnO nanostructures were identified by the spectroscope measurements of fluorescence and ultraviolet-visible absorption, and the electrical conductivity was calculated. It was found that Fe doping at 3 wt.% produced the lowest energy band gap (based on spectroscopy results) and this condition was associated with the highest electrical conductivity of 0.21 x 10-3 (Ω.cm)-1 which was calculated from the measurement of electrical resistance by two probes. Therefore, Fe doping can improve the electrical properties of ZnO nanostructures.

Effect of incorporating ultrafine palm oil fuel ash on the resistance to corrosion of steel bars embedded in high-strength green concrete

Abstract Durability degradation in reinforced concrete (RC) constructions is commonly attributed to the steel reinforcement corrosion caused by chloride. The utilization of supplemental cementitious resources, such as waste materials from industrial and agricultural sectors, typically improves the impermeability and strengthens concrete resistance to corrosion, sulfate, and acid attacks. Therefore, the prevention of steel reinforcement corrosion is greatly important in resolving challenges related to the durability and stability of RC structures, particularly when utilizing agriculture waste materials. This approach also serves as a solution for waste disposal. The aim of this study is to investigate the corrosion-resistant characteristics of high-strength concrete that contains ultrafine palm oil fuel ash (U-POFA) as a partial replacement for cement. Four high-strength green concrete (HSGC) mixes were investigated in this study with a partial replacement of ordinary Portland cement (OPC) by U-POFA at 0, 20, 40, and 60% by mass. The aim of this study is to analyze the workability, strength activity index (SAI), compressive strength, rapid chloride permeability, linear polarization resistance (LPR) by different measurement methods, and four-probe resistivity measurement by electrical resistivity measurement method of over a curing period of 7, 28, 60, and 90 days. The use of U-POFA in the different mixes results in improved workability, SAI, compression strength, and chloride penetration resistance compared with the zero-POFA mix. It is clear from the study results that adding U-POFA as a partial replacement for OPC improved the corrosion resistance of HSGC mixtures. Thus, the incorporation of U-POFA 60% succeeded in reducing the chloride ion penetration by 80% and the LPR by 93% at the test age of 90 days, compared to the reference mixture.