Toxicity of copper oxide nanoparticles: a review study

Copper oxide nanoparticles (CuO NPs) use has exponentially increased in various applications (such as industrial catalyst, gas sensors, electronic materials, biomedicines, environmental remediation) due to their flexible properties, i.e. large surface area to volume ratio. These broad applications, however, have increased human exposure and thus the potential risk related to their short‐ and long‐term toxicity. Their release in environment has drawn considerable attention which has become an eminent area of research and development. To understand the toxicological impact of CuO NPs, this review summarises the in‐vitro and in‐vivo toxicity of CuO NPs subjected to species (bacterial, algae, fish, rats, human cell lines) used for toxicological hazard assessment. The key factors that influence the toxicity of CuO NPs such as particle shape, size, surface functionalisation, time–dose interaction and animal and cell models are elaborated. The literature evidences that the CuO NPs exposure to the living systems results in reactive oxygen species generation, oxidative stress, inflammation, cytotoxicity, genotoxicity and immunotoxicity. However, the physio‐chemical characteristics of CuO NPs, concentration, mode of exposure, animal model and assessment characteristics are the main perspectives that define toxicology of CuO NPs.Inspec keywords: catalysts, nanofabrication, reviews, oxidation, toxicology, gas sensors, cellular biophysics, copper compounds, nanoparticles, biochemistryOther keywords: copper oxide nanoparticles, environmental remediation, short‐ term toxicity, long‐term toxicity, human cell lines, CuO NPs exposure, physiochemical characteristics, mode of exposure, animal model, ssessment characteristics, toxicology, time‐dose interaction, oxidative stress, inflammation, cytotoxicity, genotoxicity, immunotoxicity, toxicological hazard assessment, algae species, bacterial species, fish, rats, CuO     

Influence of wheel speed during planar flow melt spinning on the microstructure and soft magnetic properties of Fe<Subscript>68.5</Subscript>Si<Subscript>18.5</Subscript>B<Subscript>9</Subscript>Nb<Subscript>3</Subscript>Cu<Subscript>1</Subscript> ribbons

The structure and soft magnetic properties of Fe_68.5Si_18.5B₉Nb₃Cu₁ (at.%) alloy ribbons produced through planar flow melt spinning at different wheel speeds viz. 34, 17 and 12 m/s have been investigated using X-ray diffraction, differential scanning calorimetry, transmission electron microscopy, vibrating sample magnetometer and positron lifetime spectroscopy. Amorphous ribbons formed with different wheel speeds manifested different enthalpy and activation energy of crystallization. The volume fraction of nanocrystalline phase, saturation magnetization and permeability are found to increase whereas coercivity is found to decrease with increasing wheel speed on annealing. A detailed analysis of positron lifetime spectra obtained from the as-spun ribbons has been used to rationalize the variation in microstructure and magnetic properties. The presence of larger number of defects at higher wheel speed increases the volume fraction of nanocrystalline phase on annealing which improves the soft magnetic properties.     

Human Emotions Classification Using EEG via Audiovisual Stimuli and AI

Electroencephalogram (EEG) is a medical imaging technology that can measure the electrical activity of the scalp produced by the brain, measured and recorded chronologically the surface of the scalp from the brain. The recorded signals from the brain are rich with useful information. The inference of this useful information is a challenging task. This paper aims to process the EEG signals for the recognition of human emotions specifically happiness, anger, fear, sadness, and surprise in response to audiovisual stimuli. The EEG signals are recorded by placing neurosky mindwave headset on the subject’s scalp, in response to audiovisual stimuli for the mentioned emotions. Using a bandpass filter with a bandwidth of 1–100 Hz, recorded raw EEG signals are preprocessed. The preprocessed signals then further analyzed and twelve selected features in different domains are extracted. The Random forest (RF) and multilayer perceptron (MLP) algorithms are then used for the classification of the emotions through extracted features. The proposed audiovisual stimuli based EEG emotion classification system shows an average classification accuracy of 80% and 88% using MLP and RF classifiers respectively on hybrid features for experimental signals of different subjects. The proposed model outperforms in terms of cost and accuracy.     

Macromechanics study of stable fatigue crack growth in Al–Cu–Li–Mg–Ag alloy

This study was made on a fresh variety of Al–Li base alloy to investigate the role of ageing precipitates and microstructure dimensions in the fatigue crack growth resistance. The fatigue crack growth rate was measured in three different states of the material (i.e. base metal in T8 condition, friction stir weld and laser beam weld in full‐aged condition). Metallurgical analysis showed that the base metal in T8 temper is precipitation hardened by an equivalent amount of δ′ (AL₃Li), T₁ (AI₂CuLi) and θ′ (AI₂Cu) precipitates. The friction stir weld retained the morphology of strengthening precipitate; however, coarsening of Cu containing precipitates has occurred. On the other hand, laser beam weld showed a different type of CuAl phase morphology, which is characteristic of cast metal. The results of fatigue tests confirmed that fatigue crack growth resistance largely depends on microstructural features, specifically the strengthening phases. The fatigue crack resistance was in the order of base metal > laser beam weldment > friction stir weldment. The CuAl phase played a vital role in the crack closure of the laser beam weldment, thus enhancing the fatigue life as compared with the friction stir weldment, which was evident from the plot between log of da/dN (crack growth in each cycle) and log of ΔK (stress intensity range).     

Sorption potential of Moringa oleifera pods for the removal of organic pollutants from aqueous solutions

Moringa oleifera pods Lamarck (Drumstick or Horseradish) is a multipurpose medium or small size tree from sub-Himalayan regions of north-west India and indigenous to many parts of Asia, Africa, South America, and in the Pacific and Caribbean Islands. Its pods (MOP) have been employed as an inexpensive and effective sorbent for the removal of organics, i.e., benzene, toluene, ethylbenzene and cumene (BTEC) from aqueous solutions using HPLC method. Effect of different parameters, i.e., sorbent dose 0.05-0.8g, 25cm(-3) agitation time 5-120min, pH 1-10, temperature 283-308K and concentration of sorbate (1.3-13)x10(-3), (1.1-11)x10(-3), (0.9-9)x10(-3), (0.8-8)x10(-3)moldm(-3), on the sorption potential of MOP for BTEC have been investigated. The pore area and average pore diameter of the MOP by BET method using nitrogen as a standard are calculated to be 28.06+/-0.8m(2)g(-1) and 86.2+/-1.3nm respectively. Freundlich, Langumir and Dubinin-Radushkevich (D-R) sorption isotherms were employed to evaluate the sorption capacity of MOP. Sorption capacities of BTEC onto MOP have been found to be 46+/-10, 84+/-9, 101+/-4, 106+/-32mmolg(-1) by Freundlich, 8+/-0.1, 9+/-0.1, 10+/-0.3, 9+/-0.1mmolg(-1) by Langumir and 15+/-1, 21+/-1, 23+/-2, 22+/-3mmolg(-1) by D-R isotherms respectively, from BTEC solutions at 303K. While the mean energy of sorption process 9.6+/-0.3, 9.2+/-0.2, 9.3+/-0.3, 9.5+/-0.4kJmol(-1) for BTEC is calculated by D-R isotherm only. Rate constant of BTEC onto MOP 0.033+/-0.003, 0.030+/-0.002, 0.029+/-0.002, 0.027+/-0.002min(-1) at solution concentration of 1.3x10(-3), 1.1x10(-3), 0.9x10(-3) and 0.8x10(-3)moldm(-3) and at 303K have been calculated by employing Lagergren equation. Thermodynamic parameters DeltaH -8+/-0.4, -10+/-0.6, -11+/-0.7, -11+/-0.7kJmol(-1), DeltaS -22+/-2, -26+/-2, -27+/-2, -29+/-3Jmol(-1)K(-1) and DeltaG(303K) -0.9+/-0.2, -1.9+/-0.2, -2.3+/-0.1 and -2.6+/-0.2kJmol(-1) were also estimated for BTEC respectively at temperatures 283-308K. The negative values of DeltaH, DeltaS and DeltaG suggest exothermic, stable (with no structural changes at solid-liquid interface) and spontaneous nature of sorption process under optimized conditions. MOP has been used extensively to accrue and then to preconcentrate benzene, toluene and ethylbenzene in wastewater sample.     

Two-step growth of high-quality nano-diamond films using CH4/H2 gas mixture

Diamond films with fine grain size and good quality were successfully deposited on pure titanium substrate using a novel two-step growth technique in microwave plasma-assisted chemical vapor deposition (MWPCVD) system. The films were grown with varying the methane (CH₄) concentration at the stage of bias-enhanced nucleation (BEN) and nano-diamond film deposition. It was found that nano-diamond nuclei were formed at a relatively high methane concentration, causing a secondary nucleation at the accompanying growth step. Nano-diamond film deposition on pure titanium was always very hard due to the high diffusion coefficient of carbon in Ti, the big difference between thermal expansion coefficients of diamond and Ti, the complex nature of the interlayer created during diamond deposition, and the difficulty in achieving very high nucleation density. A smooth and well-adhered nano-diamond film was successfully obtained on pure Ti substrate. Detailed experimental results on the synthesis, characterization and successful deposition of the nano-diamond film on pure Ti are discussed.     

Magnetic properties and microstructure of radially oriented Sm(Co,Fe,Cu,Zr)z ring magnets

Radially oriented Sm(Co,Fe,Cu,Zr)_z ring magnets are prepared by powder metallurgy with appropriate magnetic field molding, sintering process and aging treatment. The results indicate that radially oriented Sm(Co,Fe,Cu,Zr)_z ring magnets have obvious anisotropy of thermal expansion and sintering shrinkage, which easily lead to the splits and deformation of the ring magnets. So, slow heating, vacuum pre-sintering in sintering process and various quenching processes at different steps during quenching are adopted. The magnets have excellent magnetic properties: B_r = 10.8 kGs, H_cj = 27.6 kOe, BH_max = 28.1 MGOe. Besides, there is a uniform magnetization field on the surface of the ring magnets. The average surface magnetization field () is 1.502 kGs. The deviation from average (α) is only 4.2%. The microstructure of the magnets consists of a mixture of homogeneous cellular and lamella structures.     

Effect of Charge Reservoir Layer on the Structural and Transport Properties of CuTlBa<Subscript>2−Y</Subscript>Sr<Subscript><Emphasis Type="Italic">Y</Emphasis></Subscript>-1223 (<Emphasis Type="Italic">Y</Emphasis> = 0 − 0.25) Superconductor

The bulk superconducting composites Cu_0.5Tl_0.5 Ba_2?YSr _Y Ca₂Cu₃O₁0?δ (Y = 0, 0.15, and 0.25) have been synthesized at an ambient pressure. The techniques used to characterize the samples were X-ray scans, Fourier transform infrared spectroscopy (FTIR), and dc resistivity (ρ) measurements. In CuTl-1223 system, we replaced Sr atom at Ba site and studied the superconducting properties of squeezed charge reservoir layer (CRL). From the XRD analysis, it is confirmed that the samples have orthorhombic structure and the dimensional parameters of the unit cell suppressed with the dopant atom which is most probably due to small in size of Sr atom as compared with Ba. The normal-state resistivity and critical temperatures, i.e., T _c (R = 0) and \(T_{\mathrm {c}}^{\text {onset}}\) are observed to be suppressed. The lower values of critical temperature T _c (R = 0) and activation energy U _o (eV) might be possible due to a weak flux pinning. Accordingly, a reduction of weak links and enhanced insulating nature of inter-grain coupling were observed with the doping of Sr atom in CRL. Moreover, the doping in CRL of Sr atom is also confirmed with the FTIR technique. The intrinsic parameters, i.e., coherence length ξ _c(0), crossover temperatures (T _3D?2D), inter-layer coupling (J), etc. were calculated by fluctuation-induced conductivity (FIC) analysis.     

Synthesis and characterization of ZnO nanostructures with varying morphology

Uniform fine particles of zinc oxide were prepared in three different morphologies and sizes by the controlled precipitation process from aqueous solutions of zinc nitrate in the presence of ethylene glycol. Ammonium hydroxide solution was used as the precipitant. Composition of the reactant solution, pH and temperature significantly affected the particle uniformity with respect to shape and size. Uniformity in the particles morphological feature was achieved under a narrow set of experimental conditions. pH of the reactant solutions and isoelectric point of zinc oxide were considered the master variables, controlling the particle size. One of the batch of the as-prepared zinc oxide particles was calcined at \(750{^{\circ }}\hbox {C}\), which increased its crystallinity, changed its various lattice parameters, Zn–O bond length and preferred orientation of the crystal hkl planes. Calcination had little effect on the original morphology of the zinc oxide particles.     

Sorption potential of rice husk for the removal of 2,4-dichlorophenol from aqueous solutions: kinetic and thermodynamic investigations

The sorption potential of chemically and thermally treated rice husk (RHT) for the removal of 2,4-dichlorophenol (DCP) from aqueous solutions has been investigated. Sorption of DCP by rice husk was observed over a wide pH range of 1-10. The effect of contact time between liquid and solid phases, sorbent dose, pH, concentration of sorbate and temperature on the sorption of DCP onto rice husk has been studied. The pore area and average pore diameter of RHT by BET method are calculated to be 17+/-0.6 m2g-1 and 51.3+/-1.5 nm, respectively. Maximum sorption (98+/-1.2%) was achieved for RHT from 6.1x10(-5) moldm(-3) of sorbate solution using 0.1g of rice husk for 10 min agitation time at pH 6 and 303K, which is comparable to activated carbon commercial (ACC) 96.6+/-1.2%, but significantly higher than chemically treated rice husk (RHCT) 65+/-1.6% and rice husk untreated (RHUT) 41+/-2.3%. The sorption data obtained at optimized conditions was subjected to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Sorption intensity 1/n (0.31+/-0.01) and sorption capacity multilayer C(m) (12.0+/-1.6 mmolg(-1)) have been evaluated using Freundlich sorption isotherm, whereas the values of sorption capacity monolayer Q (0.96+/-0.03 mmolg(-1)) and binding energy, b, (4.5+/-1.0)x10(4)dm(3)mol(-1) have been estimated by Langmuir isotherm. The Langmuir constant, b, was also used to calculate the dimensionless factor, R(L), in the concentration range (0.6-6.1)x10(-4) moldm(-3), suggesting greater sorption at low concentration. D-R sorption isotherm was employed to calculate sorption capacity X(m) (2.5+/-0.07 mmolg(-1)) and sorption energy E (14.7+/-0.13 kJmol(-1)). Lagergren and Morris-Weber equations were employed to study kinetics of sorption process using 0.2g of RHT, 25 cm(3) of 0.61x10(-4)moldm(-3) sorbate concentration at pH 6, giving values of first-order rate constant, k, and rate constant of intraparticle transport, R(id), (0.48+/-0.04 min(-1) and 6.8+/-0.8 nmolg(-1)min(-1/2), respectively) at 0.61x10(-4)moldm(-3) solution concentration of DCP, 0.1g RHT, pH 6 and 2-10min of agitation time. For thermodynamic studies, sorption potential was examined over temperature range 283-323 K by employing 6.1x10(-4)moldm(-3) solution concentration of DCP, 0.1g RHT at pH 6 and 10 min of agitation time and values of DeltaH (-25+/-1 kJmol(-1)), DeltaS (-61+/-4 Jmol(-1)K(-1)) and DeltaG(303K) (-7.1+/-0.09 kJmol(-1)) were computed. The negative values of enthalpy, entropy, and free energy suggest that the sorption is exothermic, stable, and spontaneous in nature.