Electrical Resistivity Values Research Articles

INVESTIGATION OF SENSITIVE ELEMENTS OF TEMPERATURE TRANSDUCERS BASED ON THERMOMETRIC MATERIAL Lu1-xScxNiSb

INVESTIGATION OF SENSITIVE ELEMENTS OF TEMPERATURE TRANSDUCERS BASED ON THERMOMETRIC MATERIAL Lu1-xScxNiSb

Влияние обработки в He:O плазме на структуру многостенных углеродных нанотрубок

The functionalization of multi-walled carbon nanotubes in He:O plasma is investigated. It's shown that plasma treatment leads to the removal of defective outer graphene layers and their fragments due to oxidation. It is established that the surface of functionalized multi-walled carbon nanotubes contains numerous uncoordinated carbon atoms and oxygen-containing functional groups. The preservation of the structure of the internal graphene layers of nanotubes and the formation of broken chemical bonds ensures a decrease in electrical resistance. At the same time, there is a narrowing of the distribution of electrical resistance values of nanotube ensembles.

Additive manufacturig of semiconductive nanocomposites throguh stereolithography

In the current work we present a series of nanocomposite materials printed via stereolithography using an acrylic organic matrix together with graphite nanoplatelets (GNP) as inorganic filler. It was generally observed that presence of GNP decreases the mechanical properties with respect to the unmodified resin, probably because the presence of pores around GNP. However, composites containing 2.5 wt% GNP showed electrical resistivity values in the range of 106 Ohm·cm, nine orders of magnitude below unmodified resin. In these conditions we state we have a material with characteristic semiconductive properties.

Comparative study of electrical resistance of disc-shaped compacts fabricated using calcined clams shell, Periwinkle shell and Oyster shell nanopowder

In this investigation, Clam, Periwinkle and Oyster shells were separately treated, calcined and ball-milled into nano powder. Each nano powder material was fabricated into disc of various lengths in three replicates. In each case, the electrical characteristics of the discs were determined. Electrical resistivity values obtained for test samples developed from Clam, Periwinkle and Oyster shells were found to be (6.024 ± 0.009) x 105 Om, (6.823 ± 0.030) x 105 Om, and (4.916 ± 0.007) x 105 Om respectively at a temperature of (25.0 ± 1.0oC). Also, electronic activation energy values were found to be 0.68eV, 0.61eV, and 0.76eV, while thermal sensitivity index values were obtained as 7850K, 7058K, and 8814K respectively for the samples fabricated from the shells of Clam, Periwinkle, and Oyster. The shell samples exhibit a negative temperature coefficient of resistance with values of - 8.83%/K, -7.94%/K and -9.92%/K for Clam, Periwinkle and Oyster shells respectively. These results provide data base on the electrical characteristics for the shells. It can be adjudged from the results that the shells are potential raw materials for NTC thermistor production. They have high sustainability and can be considered to be economically cheap since they are discarded as waste.

The effect of He : O plasma treatment on the structure of multi-walled carbon nanotubes

The functionalization of multi-walled carbon nanotubes in He : O plasma is investigated. It is shown that plasma treatment leads to the removal of defective outer graphene layers and their fragments due to oxidation. It is established that the surface of functionalized multi-walled carbon nanotubes contains numerous uncoordinated carbon atoms and oxygen-containing functional groups. The preservation of the structure of the internal graphene layers of nanotubes and the formation of broken chemical bonds ensure a decrease in electrical resistance. At the same time, there is a narrowing of the distribution of electrical resistance values of nanotube ensembles. Keywords: multi-walled carbon nanotubes, plasma treating, functionalization, transmission electron microscopy, X-ray photoelectron spectroscopy

Structural correlations for increased FOM in Pb doped Zn2SnO4 nanostructured films for applications as transparent electrode

This work reports the detailed analysis of the structure and optoelectronic properties of spin coated Zn2−xPbxSnO4 nanostructured films. XRD studies reveal the polycrystalline cubic inverse spinel structure while Raman spectra show the dominance of T2 g(3) mode and decrease in intensity of A1 g mode with Pb doped ZTO films. X-ray photoelectron spectroscopy substantiates the dominance of atom in multiple charge states and their possible substitutions in the host lattice. The maximum average transparency of 87% in 400–650 nm spectral region for x = 0.08 sample while the decrease in optical gap from 4.32 to 4.14 eV with minimal value of 4.04 eV for x = 0.04 is found. The refractive index at 500 nm is calculated using Swanepoel’s method and found to decrease from 1.72 for ZTO and 1.59 for x = 0.08 sample. The carrier concentration increases from 1018 cm−3 for ZTO to 1020 cm−3 for x = 0.08 sample. The minimal value of electrical resistivity of 2.17 × 10−3 Ω-cm and maximal Haacke’s Figure of merit (FOM) of 1.1 × 10−3/ Ω is obtained for x = 0.08. These results are significant advancement to the development of ZTO based transparent conductors for highly efficient futuristic optoelectronics and photovoltaic devices.

Combinations of polyphenols disaggregate Aβ1‑42 by passing through in vitro blood-brain barrier developed by endothelium, astrocyte, and differentiated SH‑SY5Y cells

Disaggregation of amyloid βeta (Aβ) is considered as one of the promising therapeutic strategies for Alzheimer's disease. Polyphenols are promising molecules for the disaggregation of Aβ. However, in order to find a potential therapeutic candidate, the in vitro analyses need to be performed on a model that mimics the blood‑brain barrier (BBB) as much as possible. Therefore, we aimed to establish an in vitro BBB representative transwell system by using differentiated human neuroblastoma (SH‑SY5Y), cerebral microvascular endothelial, and astrocyte cells to investigate transition and Aβ disaggregation capacity of punicalagin (PU), ellagic acid (EA), epigallocatechin gallate (EGCG), gastrodin, and their combinations on the established system. The efficiency of the established transwell systems was evaluated by measuring the transendothelial electrical resistance (TEER) and paracellular permeability coefficients (Pe) values. The transition and Aβ disaggregation capacities of the polyphenols were evaluated in the established tri‑culture transwell system based on obtained TEER (50,07 Ω.cm2) and Pe (65x10‑6 cm/s) values. Our results revealed that all polyphenols can successfully pass across the BBB system and disaggregate Aβ. While Aβ disaggregation capacities of the polyphenols were in the range of 30.52-45.01%, the percentages of their combinations were higher (75% for EGCG‑PU (Com 1) and 64% for EGCG‑EA (Com 2)). Consequently, this study provides the first evidence that Com 1 and Com 2 are promising polyphenol combinations in terms of Aβ disaggregation. Besides, the developed tri‑culture transwell system, containing differentiated SH‑SY5Y cells, may provide a new tool that closely mimics the BBB for basic research and testing of candidate agents.

Theoretical and experimental study on the electrical resistivity method for evaluating fresh concrete segregation

This paper aims to provide a theoretical foundation to support the application of the electrical resistivity method to in-situ monitoring segregation of fresh concrete. We proposed a new non-conducting sphere model and an electrical resistivity algorithm to study the correlation between the electrical resistivity and the volume fraction of coarse aggregates. Glass spheres with different sizes were used to replace coarse aggregates in validation experiments for neglecting the irregular surface of coarse aggregate particles. A modified rectangular column mold containing three pairs of electrodes at different heights was developed to evaluate the segregation of fresh concrete. The experimental results were also compared with those obtained by the conventional washing-sieving method. The applicability of the correlations between electrical resistivity values and volume fractions of coarse aggregates was confirmed. The segregation index obtained by the electrical resistivity method has a good linear correlation with the segregation coefficient obtained by the washing-sieving method. Therefore, the electrical resistivity method has a great potential for in-situ monitoring stability of fresh concrete during placement and compaction processes.

Towards physical and mechanical properties of the novel Al-Cr-Ni-Fe decagonal quasicrystal and crystalline approximants

In the present article, mechanically alloyed AlCrNiFe alloy powders, including quasicrystalline and crystalline phases, were compacted through a cold isostatic pressing at 400 MPa pressure, 25 °C temperature, and 1 h soaking time. The main objective of this work is to examine the surface porosity and relative density, microhardness, compressive strength, wettability, electrical resistivity, and optical and luminescence properties of the AlCrNiFe compacts. The effect of the crystalline/quasicrystalline structures on the mentioned properties was studied. It should be noted that the physical and mechanical characteristics of the AlCrNiFe alloys were first investigated. It was diagnosed that the Vickers microhardness of the decagonal quasicrystalline compacts possesses the maximum value of 12 GPa. The AlCrNiFe compacts containing the decagonal phase acquire the maximum compressive strength and low ductility of 363 MPa and 2.53%, respectively. The highest contact angle value (θavg = 103.3° ± 2.3°) beside the lowest wettability and surface free energy values (WA = 56.1 ± 2.8 mJ m−2, SFE = 21.1 ± 1.3 mJ m−2) belongs to the decagonal quasicrystal as compared to the PTFE. It was recognized that the presence of the decagonal quasicrystal resulted in the high electrical resistivity value of 930 μΩcm at room temperature with a negative temperature coefficient of resistivity (ρ−253/ρ27 = 1.13). Decagonal quasicrystal comprises the highest optical absorption and bandgap, which made it suitable for solar-selective absorbers.

Research on the Protective Effect of MiR-185-3p Mediated by Huangqin-Tang Decoction (HQT) on the Epithelial Barrier Function of Ulcerative Colitis.

Introduction It has been reported that the traditional Chinese medicine Huangqin-Tang decoction (HQT) has a protective effect on the epithelial barrier function of ulcerative colitis, but its mechanism has not been fully clarified. This study intends to explore the protective mechanism of HQT in regulating microRNA (miRNA) for the first time. Methods Based on the Balb/c mice ulcerative colitis model, the mice were given a gavage of 0.1 mL/10 g HQT every day for 7 days; on the 8th day, the colon of the mice was dissected, the length of the colon for the mice was measured, and the score was given based on this. Analysis of colonic mucosal injury was conducted by hematoxylin-eosin staining. Then, the differential miRNA was screened and sequenced in colon tissue using the HiSeq platform. And the differential miR-185-3p gene was verified by RT-PCR. Finally, the effects of HQT on miR-185-3p, occludin protein expression, and transepithelial electrical resistance (TEER) value were observed in combination with the CaCo2 intestinal epithelial cell model. Results HQT treatment can alleviate the shortening of colon length and reverse the intestinal mucosal injury. miRNA sequencing of colonic tissue showed that miR-185-3p was significantly downregulated in the model group, while HQT could upregulate miR-185-3p, thereby affecting the myosin light chain kinase (MLCK)/myosin light chain phosphorylation (p-MLC) pathway and leading to increased expression of occludin protein, which ultimately protected the intestinal epithelial barrier function. Conclusion HQT can protect colon epithelial barrier function by regulating miR-185-3p.

The Influence of Mineralogy and Cation Exchange Capacity toward Electrical Resistivity Value

Electrical Resistivity Tomography (ERT) is a method used for subsurface profiling in soil to characterize soil thickness, fracture zones, soil saturation, salinity and groundwater based on the electrical resistivity value (ERV). There are multiple factors that influence the electrical resistivity value, such as the porosity, degree of saturation, mineralogy, density, cation exchange capacity (CEC), and water resistivity. For this study, the effect of CEC towards resistivity value is studied via controlling the mineralogy factor, saturation, porosity and water resistivity. Thus, via understanding the CEC factor able to relate the resistivity and mineralogy of soil. This study is using a few common minerals in soil and rock, such as kaolinite, montmorillonite, illite, quartz, mica, and feldspar. The particle sizes of all tested minerals were passing 0.063mm sieve. The basic index properties of minerals such as particle size distribution, specific gravity, and Atterberg limit were tested. The instruments of Terrameter LS2 and resistivity box were used to determine the resistivity value of minerals. The Atomic Absorption Spectroscopy (AAS) machine was used to analyze the CEC of minerals via dilute with the ammonium acetate solution. The porosity and degree of saturation of minerals mixed with distill water were controlled between the range of 0.5 to 0.6 and 20% to 100%. The CEC of each mineral has different value, where the lowest and the highest minerals CEC in this study were Kaolinite and Montmorillonite at 1 and 70, respectively. The electrical resistivity values decrease with the increasing of CEC value and degree of saturation. The mineral that has higher CEC indicates lower resistivity value. Meanwhile, via increasing the degree of saturation of minerals were decrease its resistivity values.

Predictability of concrete damage level by non-destructive test methods

Non-destructive methods have many advantages over traditional test methods, especially since it does not damage the specimen, it can be used multiple times on the same specimen. These advantages also provide a great benefit in terms of following the property development in concrete as the same specimens are used which eliminates the variations related to the specimens. In this study, it is aimed to determine the damaged amount of concrete produced with different binders by electrical bulk resistivity, resonance frequency, and ultrasonic pulse velocity methods. Firstly, concretes containing different binders were produced, and along with the mechanical properties, ultrasonic wave velocity, resonance frequency, and electrical resistivity values of the produced concrete were determined at the 7, 28, and 90 days. Besides, the specimens were subjected to gradually increase compressive loads and non-destructive methods were used to estimate the extent of damage on specimens. It was attempted to establish a relationship between the damage on concrete specimens and the results obtained by non-destructive methods. Consequently, the compressive strength, electrical resistivity, ultrasonic pulse velocity and resonance frequency values of all specimens increased with the advancing age. It was concluded that the resonant frequency method is more successful than other methods in estimating the amount of damage in concrete.

The prediction analysis of compressive strength and electrical resistivity of environmentally friendly concrete incorporating natural zeolite using artificial neural network

To decrease the environmental and climatic effects of rising concrete consumption, more environmentally friendly concretes are required. One approach to achieve this goal is using natural pozzolans (NP) in concrete mixtures. Natural zeolite (NZ) as a highly reactive NP can improve concrete's durability and mechanical properties. However, tests to estimate concrete strength may take a long time and be costly. Therefore, using computational intelligence techniques, particularly artificial neural networks (ANNs), can help speed up and simplify the process. Hence, this study aims to explore the potential of employing an ANN model to predict compressive strength (CS) and electrical resistivity (ER) of natural zeolitic concrete (NZC). The experimental results of 324 NZC specimens made from 54 different mix designs are used to develop the ANN model. Seven variable inputs are considered when designing the ANN model to predict CS and ER values, including specimen age, water-to-cementitious materials ratio, cement, NZ, gravel, sand, and superplasticiser contents. Extensive computational tests were conducted to evaluate the performance of the proposed model against results obtained by experimental tests and existing gene expression programming (GEP) in the literature. The RMSE values for CS and ER are 1.65 MPa and 3.96 Ω-m, respectively, which confirm the model's accuracy and robust predictive capability. The study's findings have the potential to assist in cutting costs and saving time by using a reliable prediction technique rather than conducting costly and time-consuming tests.

All layers matter: Innovative three-dimensional epithelium-stroma-endothelium intestinal model for reliable permeability outcomes

Drug development is an ever-growing field, increasingly requesting reliable in vitro tools to speed up early screening phases, reducing the need for animal experiments. In oral delivery, understanding the absorption pattern of a new drug in the small intestine is paramount. Classical two-dimensional (2D) in vitro models are generally too simplistic and do not accurately represent native tissues. The main goal of this work was to develop an advanced three-dimensional (3D) in vitro intestinal model to test absorption in a more reliable manner, by better mimicking the native environment. The 3D model is composed of a collagen-based stromal layer with embedded fibroblasts mimicking the intestinal lamina propria and providing support for the epithelium, composed of enterocytes and mucus-secreting cells. An endothelial layer, surrogating the absorptive capillary network, is also present. The cellular crosstalk between the different cells present in the model is unveiled, disclosing key players, namely those involved in the contraction of collagen by fibroblasts. The developed 3D model presents lower levels of P-glycoprotein (P-gp) and Multidrug Resistance Protein 2 (MRP2) efflux transporters, which are normally overexpressed in traditional Caco-2 models, and are paramount in the absorption of many compounds. This, allied with transepithelial electrical resistance (TEER) values closer to physiological ranges, leads to improved and more reliable permeability outcomes, which are observed when comparing our results with in vivo data.

Investigation of the Temperature on the Thin Layers of Cobalt Oxide Produced by the Spray Pyrolysis Method Using a Solar Oven

Abstract Thin films of cobalt oxide (Co3O4) were prepared on glass substrates by the spray pyrolysis method using a solar concentrator (oven) manufactured in our laboratory. We used different processing temperatures (300° C, 350° C and 400° C). The structural, optical and electrical properties of the different samples were analyzed by X-ray diffraction (XRD), UV-Visible spectroscopy and the Hall effect measurement system. X-ray diffraction observations revealed that cubic crystals are created in all films produced, and the film structure is that of a single phase created with preferential orientation along the (311) axis in films at low temperatures, and the axis (111) for high temperatures. The grain sizes of our products vary between (22.62nm and 66.19nm), depending on the processing temperature. The optical band gap of the crystals obtained was measured. The results of the optical forbidden bands of the crystals obtained, indicated two bands of the values for each element (Eg1 and Eg2). We observed that the values of the effective optical forbidden bands increase by 2.547eV and 3.0731eV with the increase in the production temperature., In addition the film produced experiences a decrease in the Urbach parameters which vary between 162.20meV and 360.81meV depending on the increase in production temperatures. Finally, the films produced have electrical conductivity values of (1.090 [(Ω.cm)−1] to 1.853 [(Ω.cm)−1] and electrical resistivity values of 1.431 (Ω.cm) at 1.853 (Ω.cm), depending on the variation in the production temperature.

Subduction zone fluids and arc magmas conducted by lithospheric deformed regions beneath the central Andes

Dehydration of the oceanic subducting slab promotes the formation of magmatic arcs, intra-slab intermediate-depth seismicity, and hydration of the overlying mantle wedge. However, the complex permeability structure of the overriding plate controls the magma and fluid migration and their accumulation at shallower depths. In this regard, mapping the inner structure of the overriding crust and mantle is crucial to understand the magmatic and hydrological processes in subduction zones. We integrate 3-D P-wave, V_p/V_s, and electrical resistivity tomographic models of the northern Chilean subduction zone to map the magmatic and fluids derived from the subducting oceanic Nazca plate. Results show a continental crust relatively thick (50–65 km) characterized by a lower zone of high V_p values (7.2–7.6 km/s), which is interpreted as the presence of plutonic rocks. The mantle lithospheric wedge is weakly hydrated (V_p/V_s = 1.75–1.8) while the forearc continental crust is traversed by regions of reduced electrical resistivity values (< 10^2Omega m) interpreted as zones of relatively high permeability/fracturing and fluid content. These regions spatially correlate with upper plate trans-lithospheric deformation zones. Ascending melts accumulate preferentially in the back-arc, whereas hydrothermal systems form trenchward of the volcanic arc. The results highlight the complex permeability structure of the upper South American plate.

Airway epithelial dysfunction and mesenchymal transition in chronic obstructive pulmonary disease: Role of Oct-4

The airway epithelium is a dynamic tissue that undergoes slow but constant renewal. Dysregulation of airway epithelial function related to cigarette smoke exposure plays an important role in the pathophysiology of COPD. Oct4 is a transcription factor responsible for maintaining cellular self-renewal and regeneration, and CD146 and CD105/Endoglin are adhesion molecules involved in cell proliferation, differentiation, epithelial-mesenchymal-transition and tissue remodeling. Bronchial biopsy specimens (BBs) were obtained from 7 healthy controls (HC) and 10 COPD and subjected to paraffin embedding; BBs from HC were also used for epithelial cell expansion and pHBEC/ALI (air-liquid interface) culture. pHBEC/ALI were exposed to cigarette smoke extract (CSE) for 7, 14 and 21 days. In BBs, Oct4, CD146 and CD105 were evaluated by immunohistochemistry. In pHBEC/ALI, the expression of Oct4, CD146, CD105 and acetyl-αtubulin was evaluated by Western Blot, MUC5AC and IL-8 measurements by ELISA.The Oct4 epithelial immunoreactivity was lower in COPD than in HC, whilst CD146 and CD105 expression was higher in COPD than in HC. In pHBEC/ALI, Transepithelial Electrical Resistance values, measured over 7 to 21 days of differentiation, decreased by 18% (2.5% CSE) and 29% (5% CSE) compared to untreated samples. Oct4 and acetyl-αtubulin were induced after one-week differentiation and downregulated by CSE in reconstituted epithelium; CD146, CD105, MUC5AC and IL-8 were increased by CSE.Oct4 de-regulation and CD146 and CD105 overexpression, induced by cigarette smoke exposure, might play a role in airway epithelial dysfunction by causing changes in self-renewal and mesenchymal transition mechanisms, leading to alteration of epithelium homeostasis and abnormal tissue remodeling involved in progression of COPD.

The effect of hydroxyapatite on titanium pedicle screw resistance: an electrical model

BACKGROUND CONTEXTIntraoperative detection of a pedicle wall breach implicitly reduces surgical risk, but the reliability of intraoperative neuromonitoring has been contested. Hydroxyapatite (HA) has been promulgated to increase pedicle screw resistance and negatively influence the accuracy of electromyography. PURPOSEThe primary purpose of this experiment is to evaluate the effect of HA on pedicle screw electrical resistance using a controlled laboratory model. STUDY DESIGNControlled laboratory study. METHODSStimulation of pedicle screws was performed in normal saline (0.9% NaCl). The experimental group included 8 HA coated (HAC) pedicle screws and matched manufacturer control pedicle screws without HAC (Ti6Al4V). All screws were stimulated at 5, 10-, 15-, 20-, and 25-mm submersion depths. Circuit current return was recorded, and pedicle screw electrical resistance was calculated according to Ohm's Law. Data were assessed for normality and variance. Mann-Whitney U and Kruskal-Wallis tests compared groups with Bonferroni correction for multiple testing. Effect size is reported with 95% confidence intervals (95CI). p values <.05 were considered significant. RESULTSCurrent return was detected for all screws (N=24) following subclinical 8.5 µA stimulation at 5, 10-, 15-, 20-, and 25-mm submersion depths (N=144). The effect estimate of HA on pedicle screw electrical resistance is -0.07 (-0.17 to 0.01 95CI). The estimated effect of HA on pedicle screw electrical resistance did not differ across manufacturers. Electrical resistance values were inversely related to submersion depth. Electrical resistance values were lower in the experimental group at 10 mm (p=.04), 15 mm (p=.04), and 25 mm (p=.02) submersion depths. The HA effect ranged from -0.03 to -0.08 as submersion depth varied. CONCLUSIONSWe found no evidence that HA increased pedicle screw electrical resistance in a matched manufacturer control laboratory model. Electrical stimulation of pedicle screws may be reliable for pedicle breach detection in the presence of HA. Future research should investigate if laboratory findings translate to clinical practice and confirm that electrical stimulation of pedicle screws is a reliable method to detect pedicle breach in the presence of HA.

Investigation of reactively sputtered TaN thin-film resistors&#x0D; for microwave photonic applications

Electrophysical characteristics and their thermal stability of thin-film resistors based on tantalum nitride (TaN) obtained by reactive magnetron sputtering were investigated. The optimal modes of the magnetron sputtering process are determined, ensuring the Ta2N phase film composition with the value of the specific electrical resistance of 250 μm cm and high thermal stability of the parameters. On the basis of the investigations carried out, thin-film matching resistors were manufactured for use as part of an electro-optical InP-based MZ modulator

Influence of CNT Incorporation on the Carbonation of Conductive Cement Mortar

This study analyzed the influence of carbon nanotubes (CNTs) on the carbonation conductive cementitious composites. Two powder types of CNT, multi-walled and single-wall CNTs, were employed to give the cement mortar the conductivity, and four tests including the accelerated carbonation, compressive and flexural strength, electrical resistance, and porosity tests were carried out. To intentionally accelerate the carbonation, the prismatic specimens of conductive cement composites were fabricated and stored in the controlled environmental chamber at a constant temperature of 20 ± 2 °C, constant relative humidity of 60 ± 5%, and carbon dioxide (CO2) concentration of 5% for 12 weeks. It was observed that carbonation resulted in only chemical damage so that there was no change in the electrical resistance value of conductive cementitious mortar that had undergone a carbonation attack.