Effects Of Aluminum Oxide Nanoparticles Research Articles

STABILITY AND CONDUCTIVITY OF BILAYER LIPID MEMBRANE IN PRESENCE $\mathrm{Al_2O_3}$ NANOPARTICLES

The effect of aluminum oxide nanoparticles (Al2O3) on the stability and conductivity of BLM (the bilayer lipid membrane) in solution was studied. It has been shown that Al2O3 nanoparticles increase the stability of BLM in an electric field, and BLM becomes more stable with increasing their concentration. The experimental data are analyzed in terms of the well-known theory of BLM stability, which is based on the concept of spontaneous formation of microscopic pores on the BLM, the development of which leads to the loss of BLM stability. It is shown that aluminum oxide nanoparticles increase the value of the coefficient of linear tension of the pore edge, and with an increase in the concentration of nanoparticles, the linear tension also increases. It has been shown that the presence of nanoparticles in the solution leads to a decrease in BLM conductivity.

Assessing the Toxicity of Aluminum Oxide Nanoparticles (Al2O3 NPS) Prepared by Laser Ablation Technique on Blood Components

Along with its uses in a wide range of sectors, NP toxicity research was one of the fastest-growing areas of research, so the growing commercial applications brought aluminum oxide nanoparticles under the purview of toxicologists. This study shows the toxicity of Aluminum oxide Nanoparticles on blood components prepared using the pulsed laser ablation (PLA) Nd: YAG laser method. We confirmed the synthesis of aluminum Oxide nanoparticles by measuring color absorbance, UV-vis, scanning electron microscope techniques (SEM), and FTIR as characterization of Aluminum oxide Nanoparticles. The complete blood count (CBC) was used in the study of the toxicity effect of these nanoparticles on human blood parameters (in vitro). The results of hematology parameter platelet (PLT); hemoglobin (HGB–Hb); red blood cell (RBCs); white blood cell (WBCs); Count type white blood cells) are compared with the control groups, our results show no significant differences in levels of platelet (PLT); hemoglobin (HGB –Hb); red blood cell (RBCs); white blood cell (WBCs); Count type white blood cells) between the test groups when compared with control groups. This result that there indicates no toxic effect of Aluminum oxide nanoparticles in the hematology parameter (in vitro). This work is done for the first time to investigate the non-toxicity effect of these Al2O3 NPS on human blood parameters.

Effects of Aluminum Oxide Nanoparticles in the Cerebrum, Hippocampus, and Cerebellum of Male Wistar Rats and Potential Ameliorative Role of Melatonin.

Aluminum oxide nanoparticles (Al2O3 NPs) have been widely used in vaccine manufacture, food additives, human care products, and cosmetics. However, they also have adverse effects on different organs, including the liver, kidneys, and testes. Melatonin is a potent antioxidant, particularly against metals by forming melatonin-metal complexes. The present study aimed to investigate the protective effects of melatonin against Al2O3 NP-induced toxicity in the rat brain. Forty adult male Wistar rats were allocated to four groups: the untreated control (received standard diet and distilled water), Al2O3 NP-treated (received 30 mg/kg body weight Al2O3 NPs), melatonin and Al2O3 NP-treated (received 30 mg/kg body weight Al2O3 NPs + 10 mg/kg body weight melatonin), and melatonin-treated (received 10 mg/kg body weight melatonin) groups. All treatments were by oral gavages and administered daily for 28 days. Afterward, the rats were sacrificed, and samples from various brain regions (cerebrum, cerebellum, and hippocampus) were subjected to biochemical, histopathological, and immunohistochemical analyses. Al2O3 NPs substantially increased malondialdehyde, β-amyloid 1-42 peptide, acetylcholinesterase, and β-secretase-1 expression, whereas they markedly decreased glutathione levels. Furthermore, Al2O3 NPs induced severe histopathological alterations, including vacuolation of the neuropil, enlarged pericellular and perivascular spaces, vascular congestion, neuronal degeneration, and pyknosis. Al2O3 NP treatment also resulted in an intense positive caspase-3 immunostaining. Conversely, the administration of melatonin alleviated the adverse effects induced by Al2O3 NPs. Therefore, melatonin can diminish the neurotoxic effects induced by Al2O3 NPs.

Effect of aluminum oxide nanoparticles in algae biodiesel blend as a fuel in CRID engine and its performance, emission and combustion aspects

Effect of aluminum oxide nanoparticles in algae biodiesel blend as a fuel in CRID engine and its performance, emission and combustion aspects

Effect of Aluminium Oxide Nanoparticles on Tribological Properties and Noise Responses of Detroit Engine 92V Lubricant Oil

This paper focusses on the effect of aluminium oxide nanoparticles concentration on tribological properties of lubricant oil and noise response on Detroit engine 92V friction parts. The nanomaterials were produced by sol-gel production, process. The manufactured nanomaterials and the tested part were evaluated by scanning electron microscope (SEM) analysis. The coefficient of friction (CoF) and noise response were studied. Results analysis illustrated that the addition of Al2O3 nanoparticles has improved the tribological properties of the lubricating oil and decreases the wear rate of engine parts according to the decrease of CoF. Adding 1% wt. of Al2O3 nanoparticles to oil has decreased the wear rate and the CoF more than 0.5% wt. of Al2O3 nanoparticles addition.

Evaluating the Performance of Aluminum Oxide Nanoparticle-Modified Asphalt Binder and Modelling the Viscoelastic Properties by Using Artificial Neural Networks and Support Vector Machines

The effect of aluminum oxide nanoparticles (Al2O3) on the 60/70 penetration of asphalt cement (AC) was investigated in terms of the physical and rheological characteristics by using the Superpave testing procedures. Al2O3 at 3, 5, and 7% concentrations were blended with 60/70 penetration of grade AC. Conventional testing procedures were adopted regarding the physical characteristics, while dynamic shear rheometer (DSR) testing procedures were conducted to evaluate the high and low temperature failure parameters. In addition, heuristic modelling techniques, artificial neural networks (ANN), and support vector machines (SVM) were employed to predict the performance characteristics of AC by using the mechanical testing conditions. The frequency sweep test and multiple stress creep recovery (MSCR) test results revealed that the optimum composition of Al2O3 was at 5% concentration considering the high temperature performance characteristics since further addition of the Al2O3 resulted in degradation in the enhanced properties due to agglomeration of the nanoparticles in the blend. On the contrary, Al2O3 5% demonstrated the lowest viscoelastic behavior at intermediate temperatures. The higher complex modulus ( G ∗ ) and lower phase angle ( δ ) parameters indicated that the increase in stiffness due to the modification process was at the cost of losing elastic properties against fatigue cracking. Moreover, based on the statistical performance indicator, coefficient of determination (R2), it was observed that the ANN models for predicting G ∗ and δ achieved a prediction accuracy of 0.989 and 0.911 while SVM models were able to achieve 0.984 and 0.929, respectively, considering the training datasets. On the other hand, it was noted that SVM models outperformed the ANN models in terms of a smaller gap between the results obtained from the training and testing datasets. The difference between the training and testing datasets for G ∗ and δ parameters for the SVM models were 3.2% and 6.8% while for the ANN models, the differences were 11.6% and 9.5%, respectively, indicating that the ANN models were more prone to the overfitting phenomenon.

The comprehensive effects of aluminum oxide nanoparticles on the physiology of freshwater microalga Scenedesmus obliquus and it's phycoremediation performance for the removal of sulfacetamide

Nanoparticles are inevitable byproducts of modern industry. However, the environmental impacts arising from industrial applications of nanoparticles are largely under-reported. This study evaluated the ecotoxicological effects of aluminum oxide nanoparticles (Al2O3NP) and its influence on sulfacetamide (SA) biodegradation by a freshwater microalga, Scenedesmus obliquus. Although Al2O3NP showed limited toxicity effect on S. obliquus, we observed the toxicity attenuation aspect of Al2O3NP in a mixture of sulfacetamide on microalgae. The addition of 100 mg L−1 of Al2O3NP and 1 mg L−1 of SA reduced total chlorophyll by 23.3% and carotenoids by 21.6% in microalgal compared to control. The gene expression study demonstrated that ATPF0C, Lhcb1, HydA, and psbA genes responsible for ATP synthesis and the photosynthetic system were significantly downregulated, while the Tas gene, which plays a major role in biodegradation of organic xenobiotic chemicals, was significantly upregulated at 1 and 100 mg L−1 of Al2O3NP. The S. obliquus removed 16.8% of SA at 15 mg L−1 in 14 days. However, the removal was slightly enhanced (18.8%) at same concentration of SA in the presence of 50 mg L−1 Al2O3NP. This result proves the stability of sulfacetamide biodegradation capacity of S. obliquus in the presence of Al2O3NP co-contamination. The metabolic analysis showed that SA was degraded into simpler byproducts such as sulfacarbamide, sulfaguanidine, sulfanilamide, 4-(methyl sulfonyl)aniline, and N-hydroxy-benzenamine which have lower ecotoxicity than SA, demonstrating that the ecotoxicity of sulfacetamide has significantly decreased after the microalgal degradation, suggesting the environmental feasibility of microalgae-mediated wastewater technology. This study provides a deeper understanding of the impact of nanoparticles such as Al2O3NP on aquatic ecosystems.

A Mini Review of Antibacterial Properties of Al2O3 Nanoparticles.

Bacterial antibiotic resistance is one of the most serious modern biomedical problems that prioritizes the search for new agents to combat bacterial pathogens. It is known that nanoparticles of many metals and metal oxides can have an antibacterial effect. However, the antibacterial efficacy of aluminum oxide nanoparticles has been studied little compared to the well-known antimicrobial properties of nanoparticles of oxides of metals such as zinc, silver, iron, and copper. In this review, we have focused on the experimental studies accumulated to date demonstrating the antibacterial effect of aluminum oxide nanoparticles. The review discusses the main ways of synthesis and modification of these nanoparticles, provides the proposed mechanisms of their antibacterial action against gram-positive and gram-negative bacteria, and also compares the antibacterial efficacy depending on morphological characteristics. We have also partially considered the activity of aluminum oxide nanoparticles against water microalgae and fungi. In general, a more detailed study of the antibacterial properties of aluminum oxide nanoparticles is of great interest due to their low toxicity to eukaryotic cells.

Cytotoxicity Effect and Antibacterial Activity of Al2O3 Nanoparticles Activity against Streptococcus Pyogenes and Proteus Vulgaris

Aluminum oxide, often known as Al2O3, is a chemical compound of aluminum and oxygen with the formula Al2O3. It's the most common of many aluminum oxides, known as aluminum (III) oxide. The study investigates the cytotoxicity and antibacterial effects of Aluminum oxide nanoparticles (Al2O3-NPs) in different cells and bacteria. Different characterization methods such as dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) have been used to evaluate morphologies and physicochemical properties of Al2O3-NPs. MTT technique is used for determining NPs cytotoxicity. The size distribution of Al2O3-NPs was 68 ± 12 nm in diameter, while the zeta potential was (-36 ± 10 mV). There is no toxicity by using the MTT assay, as well as showed antibacterial activity was formed at 200 µg/mL, while the higher antibacterial activity was occurring at (18 ± 0.2) and (17 ± 0.1) for Proteus Vulgaris and Streptococcus pyogenes, respectively. The findings confirmed that the Al2O3-NPs have small dimensions, high stability, and increased antibacterial activity.

Subchronic Toxicity Evaluation of Aluminum Oxide Nanoparticles in Rats Following 28-Day Repeated Oral Administration

Several studies on the potential adverse effects of aluminum oxide nanoparticles (Al2O3NPs) have reported conflicting results. The present study investigated the potential adverse effects of Al2O3NPs in Sprague-Dawley rats following 28-day repeated oral administration. In addition, we aimed to determine the target organ and no-observed-adverse-effect level (NOAEL) of Al2O3NPs. Al2O3NPs was administered once daily by gavage to male and female rats at dose levels of 0, 500, and 1000mg/kg/day for 28days. There were no treatment-related adverse effects as indicated by the clinical signs, body weight, food consumption, urinalysis, ophthalmology, hematology, serum biochemistry, gross pathology, organ weight, and histopathology at all the tested doses. Under the experimental conditions of the present study, 28-day repeated oral administration of Al2O3NPs at doses of up to 1000mg/kg/day did not induce any treatment-related systemic toxicity in male and female rats. The NOAEL of Al2O3NPs was set at 1000mg/kg/day in both male and female rats and no target organs were identified.

Investigation of Effect of Aluminium Oxide Nanoparticles on the Thermal Properties of Water-Based Fluids in a Double Tube Heat Exchanger

The thermal behavior of aluminium oxide-water nanofluid in a double pipe carbon steel heat exchanger was investigated in the present study. The overall heat transfer coefficient, Nusselt, and heat transfer coefficient of nanofluid were compared with the base fluid. The volume fraction of the nanoparticles was 1%. By adding nanoparticles to the fluid, the thermal properties of the base fluid improved significantly. The hot and cold fluid flow was considered counter-current, and the nanofluid was pumped into the inner tube and once into the outer tube, and the flow rate of each fluid was 0.05 kg/s. The convective heat transfer and the overall heat transfer coefficient enhanced 94% and 253% for the hot fluid flow in the outer tube and 308 % and 144% for the hot fluid flow in the inner tube, respectively. The pressure drop calculations also showed that the pressure drop would not change significantly when using nanofluid.

Toxicological Impacts on Antioxidant Responses, Stress Protein, and Genotoxicity Parameters of Aluminum Oxide Nanoparticles in the Liver of Oreochromis niloticus.

The aim of this study was to determine the toxic effects of aluminum oxide nanoparticles (Al2O3 NPs) on oxidative stress, stress protein, and genotoxicity parameters in Oreochromis niloticus. Ninety-six-hour LC50 value of Al2O3 NPs was found as 52.4 ppm for O. niloticus. The fish were exposed to 2.6 ppm (5% of the 96-h LC50) and 5.2 ppm (10% of the 96-h LC50) for 3 days and 7 days. Various biochemical parameters, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) activities, glutathione (GSH), thiobarbituric acid reactive substance (TBARS), heat shock protein 70 (HSP70; stress protein), and genotoxicity biomarker 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, were determined. Results showed that antioxidant enzymes were significantly decreased in SOD, CAT, and GPx enzyme activity, but GST enzyme activity was significantly increased in 7 days. The oxidative stress parameters, GSH levels, were significantly decreased while 8-OHdG and TBARS levels were increased in 3 and 7 days. HSP70 levels were decreased in the concentrations of Al2O3 NPs and exposure times. Our results showed that as a result of changes in oxidative stress parameters, stress protein, and genotoxicity parameters, O. niloticus liver tissue is highly sensitive and toxic to aluminum oxide nanoparticle exposure.

Effect of aluminum oxide nanoparticles on aquatic organisms – a microcosm study

Effect of aluminum oxide nanoparticles on aquatic organisms – a microcosm study

Laboratory evaluation of self-compacting fiber-reinforced concrete modified with hybrid of nanomaterials

The idea of using nanomaterials to improve the bonding of fiber and cementitious matrix is a strategy involving simultaneous and effective use of fibers to enhance concrete mechanical properties on the one hand and decreasing concrete permeability by improving microstructure density on the other hand. Successful application of this idea in self-compacting concrete is an efficient solution for successful use of this product in production of unreinforced prefabricated elements. In this research, optimization of mixing plan of fiber concrete including optimal fiber contents, the largest nominal size of aggregate and optimal fiber size was investigated to achieve the best performance. In the first step, laboratory program including self-compacting fresh concrete tests, compressive strength, tensile strength, flexural strength, modulus of elasticity, as well as initial and final water absorption was administered and in the second step, the effect of aluminum oxide nanoparticles and silicon oxide on basalt fiber concrete designs was investigated. Results obtained from flexural strength test showed that, addition of 2 and 3% of nano-silica resulted in an increase in the concrete yield by 21 and 27% compared to non-nanomaterial fiber concrete. Similarly, the use of 2 and 3% of nano-alumina led to increased flexural strength by 10 and 15%. This improvement in the performance of nanoparticles increased the bonding between fiber and cementitious matrix in other mechanical property tests such as tensile splitting strength and modulus of elasticity. Results showed that addition of basalt fibers causes a decrease in the flowability indicators of self-compacting concrete, but it has no significant effect on compressive strength index. Additionally, application of 3% nano-silica and 3% nano-alumina in separate designs resulted in a 19 and 15% decrease in the initial water absorption of concrete, respectively, indicating improved macro, and micrometer densities of fiber concrete.

Effect of aluminium oxide nanoparticles on oilfield polyacrylamide: Rheology, interfacial tension, wettability and oil displacement studies

Polymers play an important role for oil recovery in reservoirs through the mechanism of improving mobility ratio and disproportionate permeability reduction. However, the efficiency of oilfield acrylamide polymer in reservoirs is limited because of saline brines and temperature conditions. Recently, due to their unique properties, nanoparticles (NP’s) are incorporated as additives to improve rheological properties of oilfield polyacrylamide. Nonetheless, previous studies have focussed solely on SiO2 nanoparticles. Herein, the use of metallic aluminium oxide nanoparticle was explored, exploited and evaluated. The morphology of the formulated polymeric nanofluids was determined using Fourier transform infrared (FTIR) spectroscopy. The performance of aluminium oxide (Al2O3) NP on the rheological properties of HPAM in the presence of different electrolyte concentrations representative of field brine and temperature conditions was investigated. Moreover, interfacial tension (IFT) behaviour of the polymeric nanofluid at the oil/water interface was studied used Kruss tensiometer while wettability studies was carried out using goniometer. Comparative analysis was made between the shearing, IFT, and wettability behaviour of Al2O3 polymeric nanofluid, silica (SiO2) polymeric nanofluid, and base polymer without nanomaterial. Experimental result shows that inducing oilfield polyacrylamide with nanoparticles caused an enhancement of the rheological properties, and inhibited degradation of polymer molecules in the presence of hardness brine and temperature. At 2000 ppm HPAM solution (27 mol. % hydrolysis degree) and 0.1 wt% NP concentration, Al2O3 polymeric nanofluid exhibited better steady shear performance under the different electrolyte concentration and temperature conditions studied. Besides, IFT result shows the Al2O3 polymeric nanofluid lowers the IFT of the oil/water interface and alters the wettability of sandstone cores from oil-wet to water-wet condition. Finally, heavy oil displacement test in sandstone cores showed that oil recoveries of Al2O3 polymeric nanofluid had 10.6% incremental oil recovery over conventional HPAM. This study is beneficial for extending the frontiers of knowledge in nanomaterials application for EOR.

Effect of Al2O3 nanoparticle on viscoelastic and filtration properties of a salt-polymer-based drilling fluid

ABSTRACT Conventional bentonite-based drilling fluids have associated problems while drilling troublesome or high-temperature zone due to degradation of rheological properties and excessive fluid loss. Clay particles present in the drilling fluid tend to block the pore throats and cause blockage to hydrocarbon flow. Similarly, polymers along with the filtrate loss, in the invaded zone, alter the wettability due to which there is a reduction in relative permeability to oil. All of these factors collectively cause a fall in production rates and demand stimulation jobs. The use of nondamaging drilling fluids, a particle-free salt-polymer-based drilling fluid, has addressed these problems by yielding a substantially less filtrate loss. However, at moderately high depths with high temperatures, this drilling fluid fails to maintain rheological properties and hence sagging, carrying, and fluid loss problems remerge. Sagging increases the equivalent circulation density which eventually decreases rate of penetration and induces formation damages. Hence, a need to further improve its properties is much required. This study has investigated the effect of aluminum oxide nanoparticles (Al2O3 NP) on these salt-polymer-based drilling fluids. A significant change was observed in rheological and fluid loss properties of drilling fluid (DF) when doped with different concentrations (0.5%, 0.8%, and 1%) of Al2O3 NP compared to the Base DF. Steady shear (rotational) tests were conducted to study the degree of shear thinning behavior of all the drilling fluids. It was observed that shear thinning behavior of the DF was increased with the addition of Al2O3 NP. Rotational measurements at 30°C showed a decrease in viscosity and shear stress of Al2O3 NP DF with an increase in concentration. However, at elevated temperatures of 60°C and 80°C, the reduction in viscosity of Al2O3 NP DF was substantially less than Base DF. One percent Al2O3 NP DF showed higher viscosity as compared to 0.5%, 0.8% Al2O3 NP, and Base DF at these conditions. To investigate the viscoelastic properties, oscillation tests were performed. Amplitude sweep tests showed an increase in storage modulus (G’) with an increase in Al2O3 NP concentration. While Base and 0.5% Al2O3 NP DF showed viscoelastic liquid in nature, 0.8% and 1% Al2O3 NP DF showed dominant storage properties indicating its viscoelastic solid nature at 30°C, 60°C, and 80°C. From the frequency sweep tests at higher temperatures, 0.8% and 1% Al2O3 NP DF, unlike Base and 0.5% Al2O3 NP DF, showed increase in complex viscosity at lower frequencies indicating structural build-up. Both rotational and thixotropic tests showed less structural regain time for 1% Al2O3 NP DF compared to other drilling fluid. Lastly, fluid loss control property of all the drilling fluids was investigated by measuring the filtrate loss volume in an API filter press apparatus. One percent Al2O3 NP DF showed a greater reduction in filtrate volume with Base DF showing the highest.

Effects of aluminum oxide nanoparticles on the performance, extracellular polymeric substances, microbial community and enzymatic activity of sequencing batch reactor

ABSTRACT The performance, pollutant removal rate, microbial community and enzymatic activity of a sequencing batch reactor (SBR) were investigated under oxide nanoparticles (Al2O3 NPs) stress. Al2O3 NPs at 0–50 mg/L showed no evident impact on the COD and NH4 + removals of SBR. The oxygen-uptake rate, nitrifying rate and nitrite-reducing rate slightly diminished with the increase of Al2O3 NPs concentration. Compared with 0 mg/L Al2O3 NPs, the dehydrogenase activity declined by 23.52% at 50 mg/L Al2O3 NPs. The activities of ammonia monooxygenase, nitrite oxidoreductase and nitrite reductase decreased with the increase of Al2O3 NPs concentration from 0 to 50 mg/L Al2O3 NPs. However, the nitrate reductase (NR) activity slightly increased at 5 and 15 mg/L Al2O3 NPs and declined at 30 and 50 mg/L Al2O3 NPs. The microbial reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release merely raised 14.80% and 20.72% at 50 mg/L Al2O3 NPs by contrast with 0 mg/L Al2O3 NPs, respectively. Al2O3 NPs enhanced the production, protein content and polysaccharide content of extracellular polymeric substances owing to preventing the microbes from Al2O3 NPs biotoxicity. The existence of Al2O3 NPs led to the variations of microbial richness and diversity in the SBR due to their biotoxicity.

Effect of aluminum oxide nanoparticles on the rheology and stability of a biopolymer for enhanced oil recovery

Uncommon and untested biopolymers in field pilot studies, but applied in laboratory studies are combined with Al2O3 nanoparticles to form nanocomposites for enhanced oil recovery (EOR) performance evaluation. Core plug samples of the Niger Delta region and Berea sandstone were used as the porous media for EOR experiments. Incremental oil recovery sequel to waterflooding (secondary recovery) was 5–12% and 5–7% for potato starch nanocomposite (PSPNP) and gum Arabic nanocomposite (GCNP) respectively. The biopolymer nanocomposites showed improved viscosity over the biopolymers. Thus, the nanoparticle served as a viscosity modifier on one-hand and stability enhancer on the other. EOR was affected by biopolymer and nanoparticle concentration with the attendant catch-22 situation of permeability impairment. The overall higher incremental recovery of applying PSPNP came by an intermediate potato starch (PSP) flooding between waterflooding and PSNP flooding. Consequently, slugs of biopolymer and biopolymer nanocomposite may be the way forward knowing that the biopolymers studied have surface-active constituents.

Experimental study of electrochemical mass transfer in an annular duct with the electrolyte nanofluid

The paper shows experimental studies on mass transfer phenomena in the nanofluid flowing through an annular channel. The effect of aluminium oxide nanoparticles on mass transfer was investigated in the channel with hydraulic diameter 10.5 mm.The experiment was performed using the electrochemical limiting current technique.A classical system for mass transfer measurements, based on ferricyanide ion reduction at the cathode and ferrocyanide ion oxidation at the anode has been applied. The base fluid (base-electrolyte) was composed of equimolar potassium ferri-ferrocyanide solution and sodium hydroxide solution. The nanofluid tested (nano-electrolyte) was composed of the base-electrolyte and spherical, 99.9% pure aluminium oxide nanoparticles, of about 40 nm in diameter. The nano-electrolyte used was characterized by volume particle fractions: 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.04%, 0.05% and 0.06%.Mass transfer processes during the forced transitional and turbulent flow of the nano-electrolyte through the horizontal annular channel were investigated. The fully developed hydrodynamic profile was considered. Mass transfer coefficients at the cathode attached to the inner surface of the channel were measured. The experiment was performed with the Reynolds numbers ranging from 2080 to 10430. Bulk ion concentrations in the electrolyte were measured experimentally during each test which minimized errors resulting from ion concentration decomposition. There occurred changes in the mass transfer coefficients depending both on nanoparticle concentration and the Reynolds number. With an increase in nanoparticle fraction, mass transfer was reduced. Measurements for the transitional and turbulent regime indicated that the mass transfer coefficients achieved their lowest values at the largest value of nanoparticle fraction. However, the reduction in mass transfer was not proportional to an increase in particle fraction. The maximum reduction of about 12% was observed for the largest Re numbers and the maximum particle fraction.

Aluminium oxide nanoparticles compromise spatial learning and memory performance in rats.

Recently, the biosafety and potential influences of nanoparticles on central nervous system have received more attention. In the present study, we assessed the effect of aluminium oxide nanoparticles (Al2O3-NPs) on spatial cognition. Male Wistar rats were intravenously administered Al2O3-NP suspension (20 mg/kg body weight/day) for four consecutive days, after which they were assessed. The results indicated that Al2O3-NPs impaired spatial learning and memory ability. An increment in malondialdehyde levels with a concomitant decrease in superoxide dismutase activity confirmed the induction of oxidative stress in the hippocampus. Additionally, our findings showed that exposure to Al2O3-NPs resulted in decreased acetylcholinesterase activity in the hippocampus. Furthermore, Al2O3-NPs enhanced aluminium (Al) accumulation and disrupted mineral element homoeostasis in the hippocampus. However, they did not change the morphology of the hippocampus. Our results show a connection among oxidative stress, disruption of mineral element homoeostasis, and Al accumulation in the hippocampus, which leads to spatial memory deficit in rats treated with Al2O3-NPs.