Electrical Resistivity Values Research Articles

Effect of Ni-Doping on Seebeck Coefficient of LaCoO<sub>3</sub> System

The aim of this study is discussing the results achieved on undoped and Ni-doped bulk LaCoO3 samples synthesized by solid-state reaction. The crystal structures of the samples were analyzed by x – ray diffraction (XRD) and Rietveld refinement of the XRD patterns was used to test the quality of the samples, the results of this procedure confirmed a single phase of LaCo1-xNixO3 for (x=0 and 0.05) with rhombohedral crystal structure (space group :). The main interest in this class of materials is the possibility of improving the values of Seebeck coefficient and electrical resistivity through chemical doping. The Seebeck coefficient and electrical resistivity were investigated from room temperature (RT) to 450 K, near RT the LaCoO3 system showed a large negative Seebeck coefficient, but it changed to positive value with increasing temperature while the LaCo0.95Ni0.05O3 composition showed a positive Seebeck coefficient throughout all the temperature range. Hence, within this study the Ni substitution led to decrease the electrical resistivity of the samples to one order of magnitude as a result of the partial substitution of Co3+ in LaCoO3 by Ni2+. LaCoO3 was chosen for this thermoelectric test because cobalt oxides have extensive applications.

Enhanced Thermoelectric Performance of Na0.55CoO2 Ceramics Doped by Transition and Heavy Metal Oxides

Using the solid-state reactions method Na0.55(Co,M)O2 (M = Cr, Ni, Zn, W, and Bi) ceramics were prepared and their crystal structure, microstructure, electrophysical, thermophysical, and thermoelectric properties were studied. Doping of Na0.55CoO2 by transition or heavy metal oxides led to the increase in the grain size of ceramics, a decrease in electrical resistivity and thermal diffusivity values, and a sharp increase in the Seebeck coefficient, which resulted in essential enhancement of their thermoelectric properties. The largest power factor (1.04 mW/(m·K2) at 1073 K) and figure of merit (0.702 at 1073 K) among the studied samples possessed the Na0.55Co0.9Bi0.1O2 compound, which also demonstrated the highest values of the Seebeck coefficient (666 μV/K at 1073 K). The obtained results show that the doping of layered sodium cobaltite by different metal oxides allows for improving its stability, microstructure, and functional properties, which proves the effectiveness of the doping strategy for developing new thermoelectric oxides with enhanced thermoelectric performance.

Current carrying tribological properties of multi arc ion plated titanium nitride doped silver coating

Sliding electrical contact materials play a crucial role in the transmission and conversion of electrical energy, but due to various factors such as force, electricity, and heat, the interface exhibits complex wear behavior. A single solid or liquid lubrication system can no longer meet the growing performance requirements of current carrying tribology. In this study, a TiN-Ag coating was prepared using multi arc ion plating technology, and a solid–liquid composite lubrication system was formed with ionic liquid and polyurea grease, respectively. Through current carrying friction and wear tests, their tribological properties, electrical contact resistance(ECR) values, and stability were tested, and compared with the results obtained during dry friction. The coating and worn surfaces were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results indicated that compared with dry friction, TiN-Ag coatings lubricated with ionic liquids and polyurea grease showed higher friction reduction, wear resistance, and conductivity, especially the synergistic effect between ionic liquids and coatings is prominent. The behavior of ionic liquids under voltage was analyzed, and it was found that ionic liquids formed a physical adsorption film composed of a mixture of anions and cations on the worn surface. The ordered layered structure improved the tribological performance of the system.

Screening of probiotic strains to improve visceral hypersensitivity in irritable bowel syndrome by using in vitro and in vivo approaches.

Oral administration of probiotics has been proposed as a promising biotherapy to prevent and treat different diseases related to gastrointestinal disorders, such as irritable bowel syndrome (IBS). Due to the increasing research area on the characterisation of new probiotic bacterial strains, it is necessary to perform suitable in vitro experiments, using pertinent cellular models, in order to establish appropriate readout profiles based on IBS symptoms and subtypes. In this work, a collection of 30 candidate strains, belonging mainly to the Lactobacillus and Bifidobacterium genera, were screened using three different sets of in vitro experiments with different readouts to identify promising probiotic strains with: (1) the ability to inhibit the synthesis of IL-8 production by TNF-α stimulated HT-29 cells, (2) immunomodulatory properties quantified as increased IL-10 levels in peripheral blood mononuclear cell (PBMCs), and (3) the ability to maintain epithelial barrier integrity by increasing the trans-epithelial/endothelial electrical resistance (TEER) values in Caco-2 cells. Based on these criteria, three strains were selected: Lactobacillus gasseri PI41, Lacticaseibacillus rhamnosus PI48 and Bifidobacterium animalis subsp. lactis PI50, and tested in a murine model of low-grade inflammation induced by dinitrobenzene sulfonic acid (DNBS), which mimics some of the symptoms of IBS. Among the three strains, L. gasseri PI41 improved overall host well-being by preventing body weight loss in DNBS-treated mice and restored gut homeostasis by normalising the intestinal permeability and reducing pro-inflammatory markers. Therefore, the potential of this strain was confirmed in a second murine model known to reproduce IBS symptoms: the neonatal maternal separation (NMS) model. The PI41 strain was effective in preventing intestinal permeability and reducing colonic hypersensitivity. In conclusion, the set of in vitro experiments combined with in vivo assessments allowed us to identify a promising probiotic candidate strain, L. gasseri PI41, in the context of IBS.

Delivery of Vitamins through the Intraoral Cavity with Toothpaste Using Penetration Enhancers

Dental health is rarely deemed a significant factor for a healthy life despite its considerable impact on the human body. Many presume that regular dental check-ups and daily toothbrushing are sufficient to prevent oral health diseases. However, consuming certain nutrients is also required to attain a healthy oral cavity. Nutrients necessary for preserving dental health, namely calcium, phosphorus, fluorine, and various vitamins, contribute to the development, maintenance, and repair of oral tissues. Nevertheless, it can be challenging to be conscious of taking such nutrients on a daily basis. In this study, aiming to abolish such inconveniences, vitamins essential for dental health were combined in a toothpaste formulation with penetration enhancers (PEs) to achieve intraoral delivery of the vitamins while toothbrushing. Multiple tests were performed to evaluate the characteristics of the intraoral vitamin-delivery toothpaste (IOVT), such as abrasiveness and antibacterial strength tests. The same tests were also conducted on three different commercial toothpaste to draw comparisons with the IOVT. Additionally, to verify the IOVT’s penetration capability, a mass transport study, and a transepithelial electric resistance (TEER) value test were conducted using nightcrawlers’ skin. The data collected demonstrated congruency between multiple characteristics of the IOVT and those of the commercial toothpaste. Our key finding was that the greater TEER values demonstrated the high plausibility of effective intraoral delivery of vitamins, assisted by PEs, as components of the IOVT.

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.

Coastal Groundwater Bodies Modelling Using Geophysical Surveys: The Reconstruction of the Geometry of Alluvial Plains in the North-Eastern Sicily (Italy)

The integration of various geophysical methodologies is considered a fundamental tool for accurately reconstructing the extent and shape of a groundwater body and for estimating the physical parameters that characterize it. This is often essential for the management of water resources in areas affected by geological and environmental hazards. This work aims to reconstruct the pattern and extent of two groundwater bodies, located in the coastal sectors of the North-Eastern Sicily, through the integrated analysis and interpretation of several geoelectrical, seismic and geological data. These are the Sant’Agata-Capo D’Orlando (SCGWB) and the Barcelona-Milazzo (BMGWB) Groundwater Bodies, located at the two ends of the northern sector of the Peloritani geological complex. These two studied coastal plains represent densely populated and industrialized areas, in which the quantity and quality of the groundwater bodies are under constant threat. At first, the resistivity models of the two groundwater bodies were realized through the inversion of a dataset of Vertical Electrical Soundings (VES), constrained by stratigraphic well logs data and other geophysical data. The 3D resistivity models obtained by spatially interpolating 1D inverse VES models have allowed for an initial recognition of the distribution of groundwater, as well as a rough geological framework of the subsoil. Subsequently, these models were implemented by integrating results from active and passive seismic data to determine the seismic P and S wave velocities of the main lithotypes. Simultaneous acquisition and interpretation of seismic and electrical tomographies along identical profiles allowed to determine the specific values of seismic velocity, electrical resistivity and chargeability of the alluvial sediments, and to use these values to constrain the HVSR inversion. All this allowed us to recognize the areal extension and thickness of the various lithotypes in the two investigated areas and, finally, to define the depth and the morphology of the base of the groundwater bodies and the thickness of the filling deposits.

Depth estimation of buried targets using integrated geophysical methods: comparative studies at Ahmadu bello university geophysics test site

Accurate prediction of depth and position of underground structures is a critical step in structural foundation surveys such as civil engineering excavations to adequately maintain the existing underground utilities. The study presents the results of comparative studies conducted to evaluate the performance of electrical resistivity tomography (ERT) alongside the VLF-EM method regarding depth estimation and location of buried targets of known materials, properties and dimensions. A laboratory test was carried out on the buried targets to determine the electrical properties of the buried targets before burial. The pre-burial geophysical investigation indicates no major anomaly within the site that could influence the geophysical response of the buried objects significantly. The results of the post-burial geophysical investigation indicate high variations in electrical resistivity values varying from 47 Ωm – 1081 Ωm (before) and 0.113 Ωm – 19,879 Ωm (after) the buried targets, while the VLF-EM data indicates that the current density values within the site were significantly influenced due to the presence of buried materials, confirming major influence or distortion of geophysical signature of the site. In post-burial ERT investigation, the Wenner and dipole-dipole (DD) arrays registered 67 % and 80 % degrees of alignment with the actual depth of the buried targets, respectively. Both Wenner and DD arrays show strength in depth estimation. However, the DD array indicates higher strength in terms of depth estimation and it is potentially suitable for near-surface utilities investigation due to its high precision in depth estimation. In comparison, VLF-EM captured six (6) out of eight (8) buried targets with a 47 % degree of alignment with the actual depth of the buried targets, which is far lower than the ER method, and may not be considered the most preferable method for geophysical prospecting where depth estimation of targets is of prime interest. However, the depth of targets varies from one method to another and one array to another.

Environmental Monitoring of Pig Slurry Ponds Using Geochemical and Geoelectrical Techniques

The efficient management of slurry, which is a by-product rich in nutrients derived from feces, urine, cleaning water, and animal waste that stands out for its high concentration of nutrients such as nitrogen, phosphorus, and potassium, is of vital importance, highlighting the importance of slurry management in storage ponds, which. The Murcia–Spain region has an important number of pig farms. Hence, infrastructures dedicated to managing by-products are necessary to prevent environmental pollution and eutrophication of groundwater. The aim of a recent study was to evaluate the relationship between electrical values and geochemical parameters of pig slurry stored in a pond using ERT and geochemical analysis. In addition, the study was designed to monitor the pond to determine the geochemical characteristics of the slurry and to assess the risk of lateral contamination. The study results indicate a noticeable decrease in electrical resistivity values at 0.4 and 1.6 m depth in surveys 1 and 2. The reduction ranges from 50 to 100 percent. This paper presents a new method for monitoring slurry ponds using electrical resistivity tomography. This non-invasive method provides detailed information on the distribution and characteristics of the fluids, as well as a clear picture of the electrical resistivity of the subsurface.

Electrical Resistivity Behavior of Saline Soil under Low-Temperature Conditions

Freeze-thaw cycling of frozen soils is known to be the cause of various engineering failures of infrastructure in cold regions. Researchers found that electrical resistivity methods outperform traditional ground surveying methods in frozen soils for their greater convenience and cost-effectiveness. However, detailed investigation into the relationship between the electrical resistivity of soil and a variety of soil properties is still needed. In this study, a series of laboratory experiments using the Wenner method were conducted to determine the relationship between soil electrical resistivity and soil geotechnical properties such as initial water content and pore fluid concentration under freeze-thaw conditions. Cylindrical soil samples undergo artificial freeze-thaw cycles to a temperature as low as −70°C, and electrical resistivity and temperature values are recorded simultaneously. Measurement results are summarized for curve fitting, and a statistical model showing relationship between electrical resistivity and temperature during freezing and thawing was given. Above freezing point, the log of electrical resistivity had a linear relationship with temperature. Below freezing point and above −15°C, the log of electrical resistivity had a square root relationship with temperature. Different trends in electrical resistivity change in extremely low-temperature regions (from −15°C to −70°C) are also discussed. In extremely low-temperature regions, the electrical resistivity of frozen soils did not monotonously increase with lower temperature, which may be because of increasing salt concentration in the unfrozen water phase. The findings of this study are expected to bring more insights to frozen soil structure, and assist in geophysical surveying in cold regions and construction methods utilizing ground freezing.

Durability effect of reclaimed asphalt aggregate on concrete road pavement

The use of recycled aggregates instead of natural aggregates used in concrete reduces environmental pollution and concrete costs. Recycled Asphalt Pavement (RAP) aggregate used as recycled aggregate has a lower water absorption than natural aggregate due to its bituminous structure, which reduces the water requirement of fresh concrete. In this study, it was aimed to determine the optimum use of RAP particles as aggregate in concrete for read pavements and to determine their durability properties. For this purpose, RAP was used instead of crushed stone aggregate used in concrete road construction. RAP was used by replaced aggregate 0%, 25%, 50% and 100% of the crushed stone aggregate used on the concrete road. The dose of the produced concrete was 350 kg/m3 and the water/cement ratio was kept constant as 0.45. The fresh workability and air content of concretes containing RAP were determined. Compressive strength, splitting tensile strength, electrical resistivity value, accelerated corrosion test of hardened concretes were subjected to corrosion resistance, water absorption and porosity percentage, acid resistance, ultrasonic pulse rate and Scanning Electron Microscope (SEM) and X-ray Diffractometer (XRD) analyzes were determined. In the experimental results, it has been observed that the use of RAP ratio of 25% and 50% remains within the limit values for concrete pavement. It is recommended to be used on reinforced concrete roads that will be exposed to adverse environmental conditions with its high corrosion resistance, thanks to its anti-corrosion feature.

Enhanced structural, optical and electrical properties of polycrystalline WO3 thin films achieved by aluminum nanosheets coating

Herein the effects of aluminum nanosheets on the structural, morphological, optical and electrical properties of tungsten oxide thin films are reported. Polycrystalline phase of the thermally evaporated WO3 was achieved by the pulsed laser welding technique. The polycrystalline films are then coated with Al nanosheets of thicknesses of 100 nm and 150 nm by the ion coating technique. It is observed that Al induces the domination of the hexagonal structure of WO3 over the tetragonal. Associated with the enhanced crystallinity the light absorption in the films increased by more than 60% and the energy band gap narrowed significantly. Namely the energy band gap of the as grown WO3 decreased from 3.15 eV to 2.85 eV and 2.59 eV as the Al layer thickness increased from 100 to 150 nm, respectively. It is also observed that crystalline films of WO3 exhibited lower electrical resistivity compared to films fabricated by other techniques. The temperature dependent electrical resistivity measurement was carried out in the temperature range of 310–420 K. It showed room temperature values of 2.5 ( Ω cm), 2.2 ( Ω cm) and 1.9 ( Ω cm) and impurity levels centered at 0.25 eV, 0.34 eV and 0.16 eV for uncoated and films coated with Al nanosheets of thicknesses of 100 nm and 150 nm, respectively. The enhanced crystallinity that is accompanied with narrower energy band gap and lower electrical resistivity values make crystalline WO3 films promising for optoelectronic applications.

Azilsartan improves urinary albumin excretion in hypertension mice.

Hypertension is one of the most important risk factors for chronic kidney diseases, leading to hypertensive nephrosclerosis, including excessive albuminuria. Azilsartan, an angiotensin II type 1 receptor blocker, has been widely used for the treatment of hypertension. However, the effects of Azilsartan on urinary albumin excretion in hypertension haven't been reported before. In this study, we investigated whether Azilsartan possesses a beneficial property against albuminuria in mice treated with angiotensin II and a high-salt diet (ANG/HS). Compared to the control group, the ANG/HS group had higher blood pressure, oxidative stress, and inflammatory response, all of which were rescued by Azilsartan dose-dependently. Importantly, the ANG/HS-induced increase in urinary albumin excretion and decrease in the expression of occludin were reversed by Azilsartan. Additionally, it was shown that increased fluorescence intensity of FITC-dextran, declined trans-endothelial electrical resistance (TEER) values, and reduction of occludin and krüppel-like factor 2 (KLF2) were observed in ANG/HS-treated human renal glomerular endothelial cells (HrGECs), then prevented by Azilsartan. Moreover, the regulatory effect of Azilsartan on endothelial monolayer permeability in ANG/HS-treated HrGECs was abolished by the knockdown of KLF2, indicating KLF2 is required for the effect of Azilsartan. We concluded that Azilsartan alleviated diabetic nephropathy-induced increase in Uterine artery embolization (UAE) mediated by the KLF2/occludin axis.

Impact of Metal Salt Oxidants and Preparation Technology on Efficacy of Bacterial Cellulose/Polypyrrole Flexible Conductive Fiber Membranes.

In this study, we investigated the preparation and characterization of flexible conductive fiber membranes (BC/PPy) using different metal salt oxidants on bacterial cellulose (BC) and pyrrole (Py) in the in situ polymerization and co-blended methods, respectively. The effects of these oxidants, namely, ferric chloride hexahydrate (FeCl3·6H2O) and silver nitrate (AgNO3), on the structural characterization, conductivity, resistance value and thermal stability of the resulting materials were assessed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). A comparative study revealed that the BC/PPy conductive fiber membrane prepared using FeCl3·6H2O as the oxidant had a resistance value of 12 Ω, while the BC/PPy conductive fiber membrane prepared using AgNO3 as the oxidant had an electrical resistance value of 130 Ω. The conductivity of the same molar ratio of BC/PPy prepared using FeCl3·6H2O as an oxidant was 10 times higher than that of the BC/PPy prepared using AgNO3 as an oxidant. Meanwhile, the resistance values of the conductive fiber membranes prepared from BC and PPy by the co-blended method were much higher than the BC/PPy prepared by in situ polymerization. SEM and XPS analyses revealed that when FeCl3·6H2O was used as the oxidant, the Fe-doped polypyrrole conductive particles could form uniform and dense conductive layers on the BC nanofiber surfaces. These two metal salt oxidants demonstrated differences in the binding sites between PPy and BC.

The analysis and mapping of an urban planning area in risk and hazard dimensions using earthquake-MASW-VES data: the case of Yenişehir (Bursa), Turkey

AbstractThe study area was defined by geophysical level maps and earthquake parameters. Geophysical measurements were collected from the Mesudiye formation and alluvial units. The seismic Vs–Vp–Vs30, dynamic parameter and electrical resistivity values of the layers were calculated. Vs–Vp–Gmax–σ–Ak and ρ level maps were prepared for depths of 0–5, 5–10, and &gt; 10 m. Seismic Vs30 and groundwater maps were prepared for risk/hazard and liquefaction interpretations, and a risk map was drawn from Ak–Vs30–groundwater maps. In the Mesudiye formation, the average ground amplification value is Ak = 2.21 and according to this value, the danger level is class A and low (Ansal et. all 2004). In alluviums, the average Ak was calculated as 2.51. According to this value, its class is B (medium) and the danger level is medium level. According to the level maps, it was observed that seismic velocities and electrical resistivities increased, and they were compatible with the geological units when passing to the more tight-ground Mesudiye formation from loose-porous-water-saturated alluvial units towards the north and deeper. It was determined that the alluvial grounds with low resistivity (8–30 Ohm m) are moderately corrosive–corrosive; groundwater levels are at ~ 5 m and contain different geological gradations. Therefore, the alluviums were interpreted as a risky area. This interpretation was also proved and supported with the results of the earthquake parameters. It was determined that as the magnitude of the earthquake increased, the probability of a larger earthquake occurred with a longer recurrence year. It was found that the frequency of recurrence of earthquakes with M ≤ 5.5 within 10–50–75–100 years was higher, and M ≥ 6 decreased. For M = 7.4, the average amax = 0.31 g was calculated, and it was determined the liquefaction risk is high hazard, especially in fine-gravel-sandy alluviums (in the south). Therefore, these areas may be more affected by the earthquake.

CBR Mapping Prediction from 2D Resistivity Imaging Using Regression Following Archie’s Formula

Indirect geophysical methods are increasingly associated with direct underground methods in investigating the subsurface to address environmental and geotechnical problems and reduce the cost of underground studies. These methods make it possible to explore large areas with acceptable precision, time, and cost. The present study combines the electrical resistivity method with the California Bearing Ratio for exploring an area located west of the Nouakchott port in Mauritania. The study aims firstly to verify that the thickness of the backfill layer must be less than 2 m throughout the entire study area and secondly to map areas with low California Bearing Ratio values (&lt;80%) indicating substandard backfill compaction using 2D Electrical Resistivity Tomography imaging survey and regression. The measured Electrical Resistivity values exhibit a good nonlinear regression with California Bearing Ratio, following Archie's equation. A map of California Bearing Ratio variation was derived from the Electrical Resistivity values, indicating the distribution and variation of soil strength in the study area. The results revealed that the backfill layer did not meet the standards, with approximately 35% of the total area having a California Bearing Ratio value below 80%. The areas with poor compaction requiring treatment were primarily located in the southern sector, followed by the middle and eastern sectors.

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.

Electrical Resistivity of Lead-Free Solders Reinforced by Carbon Nanospheres

Electrical resistivity of the nanocomposites Sn96.5Ag3Cu0.5 and Sn95,5Ag3,8Cu0,7 lead-free solder alloys with minor admixtures of carbon nanospheres (0.05 wt%) was measured in a wide temperature range, including a melting-solidification region. Influence of the carbon nanospheres content on electrical resistivity values has been analyzed. Carbon nanospheres were obtained by electrical discharge method from diesel fuel, cyclohexane, and aviation kerosene. The matrix samples were produced by planar flow casting technique in the form of thin ribbons. Electrical resistivity measurements were performed using four-probe method. Hysteresis between the heating and cooling electrical resistivity curves relates to the non-equilibrium solidification.

Donepezil-Loaded Nanocarriers for the Treatment of Alzheimer's Disease: Superior Efficacy of Extracellular Vesicles Over Polymeric Nanoparticles.

Drug delivery across the blood-brain barrier (BBB) is challenging and therefore severely restricts neurodegenerative diseases therapy such as Alzheimer's disease (AD). Donepezil (DNZ) is an acetylcholinesterase (AChE) inhibitor largely prescribed to AD patients, but its use is limited due to peripheral adverse events. Nanodelivery strategies with the polymer Poly (lactic acid)-poly(ethylene glycol)-based nanoparticles (NPs-PLA-PEG) and the extracellular vesicles (EVs) were developed with the aim to improve the ability of DNZ to cross the BBB, its brain targeting and efficacy. EVs were isolated from human plasma and PLA-PEG NPs were synthesized by nanoprecipitation. The toxicity, brain targeting capacity and cholinergic activities of the formulations were evaluated both in vitro and in vivo. EVs and NPs-PLA-PEG were designed to be similar in size and charge, efficiently encapsulated DNZ and allowed sustained drug release. In vitro study showed that both formulations EVs-DNZ and NPs-PLA-PEG-DNZ were highly internalized by the endothelial cells bEnd.3. These cells cultured on the Transwell® model were used to analyze the transcytosis of both formulations after validation of the presence of tight junctions, the transendothelial electrical resistance (TEER) values and the permeability of the Dextran-FITC. In vivo study showed that both formulations were not toxic to zebrafish larvae (Danio rerio). However, hyperactivity was evidenced in the NPs-PLA-PEG-DNZ and free DNZ groups but not the EVs-DNZ formulations. Biodistribution analysis in zebrafish larvae showed that EVs were present in the brain parenchyma, while NPs-PLA-PEG remained mainly in the bloodstream. The EVs-DNZ formulation was more efficient to inhibit the AChE enzyme activity in the zebrafish larvae head. Thus, the bioinspired delivery system (EVs) is a promising alternative strategy for brain-targeted delivery by substantially improving the activity of DNZ for the treatment of AD.

Tuning optical and electrical characteristics through Cu doping in spray pyrolysis fabricated Cr2O3 thin films

This study focuses on the physical properties of thin films of Cr2O3 and Cu-doped Cr2O3 (1−4 % Cu), with a thickness of approximately ∼500 nm. These films were deposited on preheated soda-lime glass substrates using the spray pyrolysis technique. The characterization of the thin films was carried out through Raman spectroscopy, UV–visible spectroscopy, and the four-point probe technique. The Raman analysis revealed vibrational modes associated with Eg and A1g symmetries in Cr2O3. The optical band gap energy exhibited a decrease from 2.92 eV to 2.6 eV with an increase in Cu content. The study also involved the evaluation of extinction coefficient, refractive index, dielectric constants, and optical conductivity of the thin films. The dispersion of the refractive index was studied using the single oscillator model (Wemple-DiDomenico). The electrical resistivity values decreased from 1000 Ω-cm to 33 Ω-cm with increasing Cu content. Notably, Cr2O3 thin films with 4 % Cu content demonstrated the best figure of merit, recording a value of 4.66 M Ω−1.