High Electrical Resistivity Values Research Articles

Determination of the geophysical signature of soft-clay and hard lateritic soils and the implications on geotechnical works using electrical resistivity imaging

Understanding the geophysical signature of subsurface is quite essential in mapping site conditions for geotechnical engineering and simulating geophysical surveys, especially in coastal areas. This article presents a comparative geophysical study of topsoil (often refer as engineering layer) of soft clay deposit and hard lateritic soil to evaluate the implications on geotechnical work using electrical resistivity imaging (ERI). The results of the 2D ERI show that the hard lateritic soil produces three distinctive geological layers with the topsoil having high apparent electrical resistivity (AER) values varying between 300 Ωm–1000 Ωm and a thickness between 2.0 m – 10.0 m. The layer between the unsaturated and saturated regions has a moderate layer AER and thickness values ranging from 100 Ωm–300 Ωm and 2.5 m–9.5 m, respectively. In contrast, the saturated (weathered) layer has a low AER value (< 100Ω m), which represents the regional groundwater unit, located beneath the subsurface of a depth > 6.0 m. However, the soft clay soil shows no distinctive subsurface layers, as it is characterized by a nearly homogeneity subsurface of poor AER variability. The top-soft clay deposit has very AER values ranging from 11.0 Ωm–80 Ωm, which extends beyond 6.5 m. Higher and lower AER values noted within the overburdened topsoil of lateritic and clay extractions, respectively, were due to the accumulations of compacted clay and lateritic soil, which are very essential for geotechnical works. In addition, the geophysical signal was conspicuously attenuated in soft clay soil, which shows that soft clay soil is not a favourite target of geophysical investigation. However, the geophysical signals in hard lateritic generate a fine geo-electrical layer pattern. It was also noted that the existence of soft clay and lateritic soil decreases with depth. This kind of information is very essential in geotechnical works.

Rietveld analysis and dielectric spectroscopy of high conductivity and low dielectric loss Co Zn La ferrite

ABSTRACT This study investigates structural and dielectric characteristics of Co0.65Zn0.35LaxFe2-xO4 (CZL), with (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1), synthesized using the flash auto-combustion approach. The Fourier transform infrared spectroscopy supports the X-ray results for forming single-phase spinel structure. The Debye Scherer’s formula was used to evaluate the average crystallite size that found within the range of 31.5–46 nm. With increasing La3+ concentration, the lattice parameter, cell volume and density decreased. The formation of nanoparticles was supported by transmission electron microscopy TEM examination, which was coinciding with nanoparticle size from (XRD) data. The sample x = 0.06 has the highest value of resistivity and the lowest dielectric loss. The high value of electrical resistivity in ferrite is suitable for the high frequency application where eddy current losses are appreciable. The dielectric constant decreases with increasing La content, implying that the material’s dielectric properties are very useful for electron magnetic wave absorption applications.

Geophysical research of underground hydraulic structures, old Glubochinsky water tunnel case study

Research objective is to study the features of geophysical fields and parameters in the area of the artificial underground water tunnel and estimate the capabilities of geophysical methods of identifying hidden underground industrial facilities. Methods of research. Measurements of self-potential signals (SP) were carried out using nonpolarizing electrodes and an electrical exploration receiver. The magnetic exploration was carried out by a proton magnetometer. Electrotomography was carried out using multielectrode electrical survey equipment with a Schlumberger symmetrical scheme of surveys. The microseismic background was recorded using an autonomous seismic station. The georadar survey was carried out using the SIR-3000 ground penetrating radar and antennas with the frequencies of 100 MHz and 270 MHz. Results. Based on the survey results, graphs of magnetic and self-potential fields, electrotomographic and microseismic sections, and radarogram were built on the research profile. The research has shown different levels of the magnetic field and the SP in the area of volcanic rocks and dikes of gabbro-dolerites occurrence. A significant increase in microseismic noise was observed with an increase in the weathering crust thickness. A local decrease in the SP potential, abnormally high values of specific electrical resistivity and intensive reflections of radio waves from the tunnel top were recorded above the underground water tunnel. Conclusions. Qualitative and quantitative geophysical characteristics were obtained in the area of the old underground water tunnel. The research showed different levels of the magnetic field and spontaneous polarization potentials in the occurrence area of rocks of different composition. A significant increase in microseismic noise was recorded with an increase in the weathering crust thickness. Geophysical signs of the boundaries between geological structures and artificial underground objects are revealed. The exact position and depth of the old underground tunnel of Glubochinsky hydraulic structures was determined.

Features of the Physical-Mechanical Properties and Chemical Composition of Chert Gravels

The chert gravels are a by-product of sand mining in the south of Israel; the reserves amount to tens of millions of tons and continue to grow. The attempts of their comminution for the production of aggregates by conventional mechanical methods have not yet been successful due to the high abrasiveness, as well as the flaky form of their fracturing. This study was motivated by the need to find an alternative method to rock comminution that would ensure aggregate production in line with the requirements of the asphalt and concrete industry. This article deals with the first inevitable stage on the way to this goal, which consists of an extensive laboratory study of the physical and mechanical properties of the chert gravels, as well as the features of their chemical composition. The results show that the chert rock, consisting of quartz micro grains, contains calcium, sulfur, phosphorus, and barium impurities. The rock is characterized by extremely low porosity and water absorption (less than 1%) and high values of tensile strength (10.8 ± 3.3) and electrical resistivity (23.0 ± 11.9 kΩm). The cubic uniaxial compression strength of the rock is relatively not high (37.3 ± 10.4 MPa), which contradicts the assessment made based on the Schmidt hammer and Point Load studies (158 ± 30.4 MPa and 321 ± 118.5 MPa, respectively).

Towards understanding the extent of saltwater incursion into the coastal aquifers of Akwa Ibom State, Southern Nigeria using 2D ERT

The hydro-lithostratigraphic units of the coastal area of Akwa Ibom State, Southern Nigeria were investigated involving electrical resistivity tomography (ERT) and Wenner array. This procedure and electrode configuration were adopted because of their wide range of sensitivity and inherent characteristics to geological materials. This study is aimed at defining the extent of saltwater invasions into the coastal and inland aquifers. The investigated area is divided into three zones A (≤0 < 20 km), B (<20 < 40 km), and C (>40 km)) based on the distance from the survey locations to the shoreline. The saline aquifer of the control tomogram obtained at the shoreline (Ibeno Beach) is characterized by the electrical resistivity of 0.159–3.55 Ωm. Within Zone A, (Ukpenekang, Eastern Obolo, and Okoro Ette), the saline aquifer is defined by electrical resistivity values of 0.33–44.0 Ωm, 2.07–48.5 Ωm, and 8.0–60.0 Ωm respectively. In general, the Zone B saline aquifers are defined by electrical resistivity values of 0.602–64.5 Ωm. Furthermore, the third zone which is situated a distance >40 km from the shoreline, is described by relatively higher electrical resistivity values (38.9–3260 Ωm) and indicates a region free from saltwater incursions. Generally, the 2D ERT models showed that electrically resistivity values increase progressively inland.

New insights into arsenic and cadmium distribution and origin in paddy soils using electrical resistivity tomography

In-situ geophysical techniques based on electrical resistivity tomography were performed to determine the spatial and temporal distribution of heavy metals. This paper aimed to pursue a novel methodology consisting in combining electrical resistivity tomography measurements, soil chemical data, and statistical analysis to predict As and Cd distribution in paddy soils. The resistivity surveys were performed at 2 m depth in nine locations of Tolima district in Colombia. Chemical concentrations of both As and Cd were introduced in a standardization procedure to estimate their electrical resistivity values. Soil and fertilizers information were acquired to determine As and Cd input in the studied area. The laboratory standardization showed a direct linear regression for Cd and an inverse one for As. A high positive Spearman correlation between electrical resistivity and As / Cd content was determined, with 0.98 and 0.99 values, respectively. Results showed that As-like compounds were distributed mainly in shallower soil layers (0.45 m) and were characterized by lower electrical resistivity values (181–2318 Ω.m). On the contrary, Cd-like compounds were observed in a deeper profile (0.80 m) with higher electrical resistivity values (559–4879 Ω.m). This work underlies the utility of the combined geophysical techniques, soil chemical parameters and statistical analysis to improve the understanding of As and Cd dynamics and origin in topsoil, supporting the need of an agricultural management of paddy soils.

Investigation of a novel technology of stud spraying aluminum alloy on the copper surface

Stud spraying is a novel spraying technology developed from stud welding technology. It is a technology where the coating is prepared by contacting the contact surface of a resistively heated molten metal. Using the spraying voltage of 30–70 V to prepare the aluminium alloy coating on a copper plate, the optimum stud spraying parameters are identified. Electrical resistance measurements and microhardness tests show that the aluminium alloy coating has high microhardness and low electrical resistance values. The average microhardness of the coating is approximately 208 HV which is 2.5 times the microhardness of the copper plates. The surface of the coating was observed by scanning electron microscope (SEM) to have distinct crystal structures. Analysis of the coating using energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) shows that these microstructures are mainly composed of intermetallic compounds (IMCs) such as Al2Cu and Al4Cu9.

Dual effect of TAT functionalized DHAH lipid nanoparticles with neurotrophic factors in human BBB and microglia cultures

BackgroundNeurodegenerative diseases (NDs) are an accelerating global health problem. Nevertheless, the stronghold of the brain- the blood–brain barrier (BBB) prevents drug penetrance and dwindles effective treatments. Therefore, it is crucial to identify Trojan horse-like drug carriers that can effectively cross the blood–brain barrier and reach the brain tissue. We have previously developed polyunsaturated fatty acids (PUFA)-based nanostructured lipid carriers (NLC), namely DHAH-NLC. These carriers are modulated with BBB-permeating compounds such as chitosan (CS) and trans-activating transcriptional activator (TAT) from HIV-1 that can entrap neurotrophic factors (NTF) serving as nanocarriers for NDs treatment. Moreover, microglia are suggested as a key causative factor of the undergoing neuroinflammation of NDs. In this work, we used in vitro models to investigate whether DHAH-NLCs can enter the brain via the BBB and investigate the therapeutic effect of NTF-containing DHAH-NLC and DHAH-NLC itself on lipopolysaccharide-challenged microglia.MethodsWe employed human induced pluripotent stem cell-derived brain microvascular endothelial cells (BMECs) to capitalize on the in vivo-like TEER of this BBB model and quantitatively assessed the permeability of DHAH-NLCs. We also used the HMC3 microglia cell line to assess the therapeutic effect of NTF-containing DHAH-NLC upon LPS challenge.ResultsTAT-functionalized DHAH-NLCs successfully crossed the in vitro BBB model, which exhibited high transendothelial electrical resistance (TEER) values (≈3000 Ω*cm2). Specifically, the TAT-functionalized DHAH-NLCs showed a permeability of up to 0.4% of the dose. Furthermore, using human microglia (HMC3), we demonstrate that DHAH-NLCs successfully counteracted the inflammatory response in our cultures after LPS challenge. Moreover, the encapsulation of glial cell-derived neurotrophic factor (GNDF)-containing DHAH-NLCs (DHAH-NLC-GNDF) activated the Nrf2/HO-1 pathway, suggesting the triggering of the endogenous anti-oxidative system present in microglia.ConclusionsOverall, this work shows that the TAT-functionalized DHAH-NLCs can cross the BBB, modulate immune responses, and serve as cargo carriers for growth factors; thus, constituting an attractive and promising novel drug delivery approach for the transport of therapeutics through the BBB into the brain.

Microhardness, Resistivity and Tribological Properties of Coatings Based on Hf/Hfn Bilayers Deposited By Sputtering

In this work, coatings based on hafnium/hafnium nitride (Hf/HfN) bilayers were synthesized by the magnetron sputtering technique, producing coatings with 4, 8 and 16 Hf/HfN bilayers on AISI 316L steel and silicon (100). The surface morphology was studied, which shows a high uniformity of grain cluster groupings. Their microhardness was evaluated where the hardness of the 316L steel was improved by more than 3 orders of magnitude, with a value of 6.71 GPa for 8 Hf/HfN bilayers, this same condition reached a high value of electrical resistivity of 6.55x1014 µΩ-cm, a reduction in the coefficient of friction by about 25% with respect to 316L and presented a total delamination of the coating at 19.77 N, which could allow these coatings to be canted for corrosion protection of 316L steel.

Role of disorder in magnetic and conducting properties of U–Mo and U–Mo–H thin films

Crystal structure, magnetic and electrical properties of thin U–Mo films and their hydrides prepared by reactive sputter deposition from metallic targets were studied. The films are metallic but with high values of electrical resistivity. Both bcc U0.79Mo0.21 thin film and the hydride (UH3)0.74Mo0.26 (β-UH3 structure type) have a very strong texture. Superconductivity is identified below Tc = 0.55 K for U0.79Mo0.21. The critical field of 1.0 T is exceeding that of α-U (0.3 T). The hydride film (UH3)0.74Mo0.26 is a ferromagnet with the Curie temperature TC = 165 K, higher concentration of Mo somewhat reduces the TC value. Deposition on a cooled substrate reduces the grain size of the hydride, approaching the limit of amorphous state. The U–Mo films and hydrides exhibit the net negative temperature coefficient of resistivity, TCR = dρ/dT, attributed to the randomness on atomic scale, yielding very strong scattering of electrons and weak localization.

Fused filament fabrication of commercial conductive filaments: experimental study on the process parameters aimed at the minimization, repeatability and thermal characterization of electrical resistance

Nowadays, a challenging scenario involving additive manufacturing (AM), or 3D printing, relates to concerns on the manufacturing of electronic devices. In particular, the possibility of using fused filament fabrication (FFF) technology, which is well known for being very widespread and inexpensive, to fabricate structures with embedded sensing elements, is really appealing. Several researchers in this field have highlighted the high electrical resistance values and variability in 3D-printed strain sensors made via FFF. It is important to find a way to minimize the electrical resistance and variability among strain sensors printed under the same conditions for several reasons, such as reducing the measurement noise and better balancing four 3D-printed strain gauges connected to form a Wheatstone bridge to obtain better measurements. In this study, a design of experiment (DoE) on 3D-printed strain gauges, studying the relevance of printing and design parameters, was performed. Three different commercial conductive materials were analyzed, including a total of 105 printed samples. The output of this study is a combination of parameters which allow both the electrical resistance and variability to be minimized; in particular, it was discovered that the “welding effect” due to the layer height and printing orientation is responsible for high values of resistance and variability. After the optimization of printing and design parameters, further experiments were performed to characterize the sensitivity of each specimen to mechanical and thermal stresses, highlighting an interesting aspect. A sensible variation of the electrical resistance at room temperature was observed, even if no stress was applied to the specimen, suggesting the potential of exploiting these materials for the 3D printing of highly sensitive temperature sensors.

Tuning thermoelectric properties of Ca0.9Gd0.1MnO3 by laser processing

Donor-doped CaMnO3 is an n-type semiconductor with perovskite structure, being considered as a potential n-type leg in thermoelectric modules. This oxide presents stability at high temperatures and allows tuning the relevant electrical and thermal transport properties through doping. In this work, Ca0.9Gd0.1MnO3 precursors have been prepared to produce fibres through the laser floating zone technique using different pulling rates. However, as-grown fibres did not present thermoelectric properties due to the presence of high amounts of secondary phases, leading to very high electrical resistivity values. The results have highlighted the importance of annealing procedures to reduce electrical resistivity, due to the decrease of secondary phases amount, and producing promising thermoelectric performances. The annealed samples present higher ZT values when the growth rate is decreased, reaching around 0.22 for the lowest growth rate, which is very close to the best values reported in the literature for these materials. Moreover, this procedure possesses an additional advantage considering that these samples can be directly used as n-type legs in thermoelectric modules for high-temperature applications. However, further studies should be made to determine the optimal amount of dopant.

Geophysical investigation for sustainable development at Alamein Area, Northwestern Coast, Egypt

Alamein City is one of the recently established cities along the Mediterranean coast in Egypt. Nineteen vertical electrical soundings (VES's) were measured in the study area with maximum current electrode separation of 600 m to examine the depth to water bearing layer, subsurface succession and structures controlling the distribution of the groundwater aquifer. The interpretation results of the VES data revealed that the subsurface section in the area is subdivided into three geoelectrical layers. The uppermost layer covers the ground surface and consists of alluvial deposits with moderately high electrical resistivity values (10.5–291 Ω.m.), with thicknesses ranging from 0.8 to 12.2 m. The second layer consists of Limestone (L. St.) intercalated with clay (water bearing layer) with low electrical resistivity values (0.2–10 Ω.m); with thicknesses ranging from 1.4 to 34 m. The third layer consists of saturated oolitic limestone with moderate electrical resistivity values (5.5–120 Ω.m). Gravity data were retrieved, corrected and analyzed. Gravity interpretation reveals that the depth of the basement rocks varies from 3600 to 6400 m with basement faults extending mainly in NW-SE direction, which is corresponding to the major trend in the Northern Western Desert.

P-Glycoprotein-Mediated Efflux Using a Rapidly Maturing Caco2 Clone (CLEFF4) in Only 5 Days without Requiring Modified Growth Medium.

In drug discovery it is essential that one of the parameters tested for any new chemical entity is its affinity for human efflux systems, most notably P-glycoprotein (P-gp). These efflux systems affect not only rates of oral absorption but also rates of excretion through the liver, blood-brain barrier, and accumulation in potential target cells that upregulate efflux systems. Current methods to determine drugs' P-gp transport potential include in vitro bidirectional transport studies, and the two most common cell lines used are Caco2 and MDR1-transfected MDCK models. Caco2 cells are human but slow growing and require more than 3 weeks to mature, while MDCK cells are canine, but when transfected with human P-gp become a rapid model of P-gp affinity. Our laboratory has generated a Caco2 subclone called CLEFF4 that is fully human, yet now approaches the rapid nature of the MDCK model. No special medium is required. We have shown, in as little as 5 days postseeding, high transepithelial electrical resistance values of more than 1000 Ω·cm2 plus P-gp expression more than threefold higher than that of 21-day-old cells. Currently tested drugs included rhodamine 123 (Rh123), vinblastine, and doxorubicin, and all drugs exhibited P-gp-mediated efflux that was inhibited by PSC833. By day 6, bidirectional transport of Rh123 was as potent as that of mature Caco2 cells, for use in comparative P-gp affinity studies. We now have a human P-gp model that is rapid and works without any need for special accelerating medium. We believe this could be a welcome addition to the testing regime of new chemical entities.

Glacier–Permafrost Interaction at a Thrust Moraine Complex in the Glacier Forefield Muragl, Swiss Alps

The internal structures of a moraine complex mostly provide information about the manner in which they develop and thus they can transmit details about several processes long after they have taken place. While the occurrence of glacier–permafrost interactions during the formation of large thrust moraine complexes at polar and subpolar glaciers as well as at marginal positions of former ice sheets has been well understood, their role in the formation of moraines on comparatively small alpine glaciers is still very poorly investigated. Therefore, the question arises as to whether evidence of former glacier–permafrost interactions can still be found in glacier forefields of small alpine glaciers and to what extent these differ from the processes in finer materials at larger polar or subpolar glaciers. To investigate this, electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) surveys were carried out in the area of a presumed alpine thrust moraine complex in order to investigate internal moraine structures. The ERT data confirmed the presence of a massive ice core within the central and proximal parts of the moraine complex. Using GPR, linear internal structures were detected, which were interpreted as internal shear planes due to their extent and orientation. These shear planes lead to the assumption that the moraine complex is of glaciotectonic origin. Based on the detected internal structures and the high electrical resistivity values, it must also be assumed that the massive ice core is of sedimentary or polygenetic origin. The combined approach of the two methods enabled the authors of this study to detect different internal structures and to deduce a conceptual model of the thrust moraine formation.

Structural, Morphological and Magnetic Characterization of Sm-substituted Ni-Zn Ferrite

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.

Investigation on Dielectric Material Selection for RF-MEMS Shunt Capacitive Switches Using Ashby, TOPSIS and VIKOR

In this paper, different material selection techniques like Ashby, TOPSIS and VIKOR have been used to select the best dielectric material for RF-MEMS switches with low power consumption. These methods help in choosing the optimum material from the available pool of materials. The dielectric material should be selected such that RF-MEMS capacitive switch should have good RF response, high thermal conductivity, low thermal coefficient of expansion, and low leakage current. For this purpose, the concerned material indices should have high value of relative permittivity, high value of electrical resistivity, low value of thermal coefficient of expansion, and high value of thermal conductivity. The presence of trade-offs led to no conclusive selection in case of Ashby’s method. Following Ashby’s method, TOPSIS and VIKOR method were used to select the optimum material. The end results suggest that TiO2 is the most suitable materials for shunt capacitive RF-MEMS switches.

Mapping of subsurface contamination zone using 3D electrical resistivity imaging in Hilla city, Iraq

Electrical resistivity imaging (ERI) method is very useful in mapping subsurface contamination zones. In this study, 3D ERI is used to identify the distribution and depth of subsurface soil contamination zone near Al_Furat state company for chemical and pesticides industries in Hilla city, Iraq. A 3D pure image of electrical resistivity distribution is obtained from a perpendicular square grid (80 × 80 m) which consists of three parallel and three perpendicular lines. The electrical resistivity values range from < 1 to 21 O.m, and the total root mean square (RMS) after four iterations is about 7%. The image gives eight different depth slices for the estimated model with a depth interval of about 1 m. The maximum depth of investigation is 13.7 m. The results mapped the contamination zone, where high electrical resistivity values (about 21 O.m) are observed possibly due to accumulation of alkaline waste disposed from the company. The ERI results show that the subsurface layers up to a depth of 4.99 m are of moderate-to-high electrical resistivity values. The study reveals that 3D ERI is an effective tool for subsurface contamination zone mapping in various depths, which extends in this study from the near-surface to a depth of about 5 m below the ground level.

Research of metallurgical properties of high-ash coal for the production of ferro-alloys

In laboratory conditions researches on studying of metallurgical properties of high-ash reducing agents on the example of stone coals of the Borly Deposit are carried out. Physical and chemical characteristics of the studied coals are determined: strength, density, porosity, electrical resistivity and reactivity. A comparative analysis of the properties of coal with known reducing agents of ferroalloy production: Magnitogorsk and Chinese cokes, Angarsk and Leninsk-Kuznetsk semi-coxes. It was found that the studied coals have high values of electrical resistivity and reactivity, providing intensive reduction of oxides of charge materials, as well as contributing to a more complete use of the furnace power. Indications of mechanical strength test coal meet the requirements for carbon-containing raw materials used for the production of ferroalloys according are 50-60%. The main strength characteristic of carbon reducing agents used in the Ferroalloy industry is their structural strength, the values of which should be within 45-55% according. The structural strength of the coal under study is quite high and is 81.35 % and close in value to the Magnitogorsk coke 87.5 %. Indicators of reactivity is of 8.61 ml/g∙s and comparable with the values of Leninsk-Kuznetsk of 8.02 ml/g∙s and the Angarsk 9,80 ml/g∙ s semi-coxes. In general, the metallurgical properties of high-ash Borlin coals are within acceptable limits and fully meet the requirements for reducing agents used in the production of ferroalloys.

Characterization of the IPEC-J2 MDR1 (iP-gp) cell line as a tool for identification of P-gp substrates

Recently, we transfected the porcine intestinal cell line IPEC-J2, with human P-glycoprotein (P-gp, ABCB1). The resulting cell line, iP-gp, has a high expression of functional human P-gp in the apical membrane, and a low expression of nonhuman ATP-binding cassette (ABC) transporters. The aim of the present work was to investigate the usability of iP-gp cell line for determining transepithelial transport kinetics of the prototypical P-gp substrates digoxin and rhodamine 123.The cell line generated tight monolayers after 16days of culture, reflected by high transepithelial electrical resistance values (TEER>15,000Ω·cm2), immunocytochemistry and low fluxes of the paracellular flux marker [14C]-mannitol. Monolayer integrity was not affected the common solvents dimethyl sulfoxide (DMSO), methanol and ethanol in concentrations up to 2% (v/v).Transepithelial fluxes of [3H]-labeled digoxin and rhodamine 123 were measured at varying donor concentrations, and kinetic parameters were estimated. Km and Vmax of P-gp mediated basolateral-to-apical (B-A) flux of rhodamine 123 were estimated to 332±124μM and 111±16pmol·cm−2·min−1 (n=3, total N=6), respectively. Vmax and Km of digoxin B-A flux could not be estimated due to the low aqueous solubility of digoxin. The half maximal inhibitory concentrations (IC50) of the selective P-gp inhibitor, zosuquidar (LY-335979), were estimated to 0.05±0.01μM (n=3, total N=6) and 0.04±0.01μM (n=3, total N=6) in transport experiments with digoxin and rhodamine 123 as substrates, respectively. Bidirectional fluxes of digoxin and rhodamine 123 were measured in transfected Madin Darby canine kidney cells (MDCK II MDR1) and compared with the fluxes obtained with the iP-gp cell monolayers. Efflux ratios were highest in the iP-gp cells, due to a tighter paracellular pathway. In conclusion, both digoxin and rhodamine 123 could be used to obtain IC50 values of inhibition, Ki values were only possible to obtain using rhodamine 123. The observed tightness, robustness towards solvents and the high efflux ratios confirmed that the iP-gp cell line may serve as a useful screening tool for investigations of substrate-P-gp interactions and modulation of P-gp function.