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An experimental assessment of thermo-physical, tribological, and eco-friendly properties of polyolester (POE) oil with zinc oxide (ZnO) nanoparticles for use as nanolubricant in refrigeration compressor. The ZnO nanolubricants were added in the mass fractions in the range from 0.1% to 0.5%, at the temperatures of 0 °C, 20 °C, 30 °C, 40 °C, and 60 °C. The thermophysical properties include thermal conductivity, kinematic viscosity, flash point, fire point, pour point, and cloud point with respect to various proportions. The morphology and size of ZnO nanoparticles are studied using the scanning electron microscope test. The tests findings suggest that ZnO nanoparticles greatly improved the friction characteristics of pure POE oil. The addition of the concentration decreases the pour point by 13.6%; at the same time, the flashpoint is improved by 3.5% when the POE oil is blended with ZnO. Zinc oxide nanoparticles could improve the refrigerants’ performance by extending life and avoiding friction problems. The optimum ZnO content of nanolubricants is, therefore, 0.3% for the POE/ZnO nanoparticles addition. The COF values are reduced by 6.95% at the optimum concentration over that with POE oil. The nanoparticles’ addition up to 0.3% results in less wear as they provide a defensive film between the surfaces during their motion. The mass loss value increased due to the aggregation of ZnO nanoparticles. The higher thermal conductivity is obtained for the 0.3% volume fraction of nanoparticles, and other 0.1% and 0.5% volume fractions lesser.

In the present study, the photocatalytic effect of the addition of nano-TiO2/ZnO particles with different molar ratios of polyethylene glycol on the self-cleaning behavior and antibacterial activity of Portland cement was investigated to evaluate its potential for dye decolorization, and inactivation of Escherichia coli and Streptococcus mutans. Moreover, the effect of PEG addition on the hydration and tensile strength properties of the cement samples was evaluated. Furthermore, to study the self-cleaning behavior of the cement samples, an azo dye was selected as an organic pollutant. The modified cement samples were characterized using x-ray diffraction, Fourier-transform infrared spectroscopy, energy-dispersive x-ray spectroscopy, and scanning electron microscopy to assess the pozzolanic reactivity of the cement paste in the presence of TiO2 and ZnO nanoparticles. The results showed that the bactericidal properties of the modified cement specimens were dependent on the hydration time and composition of the samples. Accordingly, the maximum inhibitory effect was observed for the specimens hydrated for 7 d. Additionally, the surface of the samples was able to effectively decompose the azo dye. This novel modified cement has a promising potential to be used as a self-cleaning and antibacterial coating for urban constructions.

Nanotechnology is one of the most significant area of research worldwide because of its tremendous applications linked to the high surface area to volume ratio, improved pharmacokinetic profile and targeted drug delivery. In the current study, zinc oxide nanoparticles (ZnO NPs) were synthesized from Achyranthes aspera leaf extract, characterized by UV-visible spectroscopy, XRD, SEM, FTIR, AFM and evaluated for antibacterial efficacy against poultry pathogenic bacterial strains. UV-visible absorption peak was found at 370 nm. XRD showed hexagonal wurtzite structure of ZnO NPs while SEM results indicated an average size less than 100 nm with a minimum and maximum size of 28.63 and 61.42 nm, respectively. Further analysis of synthesized nanoparticles by FTIR showed stretching frequency at 3393.14 cm−1, 2830.99 cm−1, 2285.23 cm−1, and 2108.78 cm−1. The antibacterial activity of synthesized nanoparticles was investigated against common poultry pathogens Salmonella gallinarum and Salmonella enteritidis by the agar well diffusion method. The zone of inhibition with a diameter of 31 mm was observed against S. enteritidis and 30 mm against S. gallinarum that was greater than the antibiotic (tetracycline) used. The minimum inhibitory concentration (MIC) was 0.195 and 0.390 mg ml−1 for different bacterial strains. Characterization with different techniques showed a uniform and stable synthesis of ZnO NPs. Furthermore, the findings confirm the higher antibacterial activity of nanoconjugate in comparison to leaf extract and pure drug against pathogenic bacteria.

(Sm, Co) co-doped ZnO nanoparticles (Zn1−2xSmxCoxO), 0.00 ≤ x ≤ 0.06 , have been prepared by the co-precipitation technique. The effect of the dopant ions Sm3+ and Co2+ on the structural, morphological, and electrical conductivity of ZnO has been studied. XRD analysis shows the substitution of Zn2+ ions by the co-doping Sm3+ and Co2+ ions with the formation of secondary phases as Sm2O3 and Co3O4 upon 0.005 co-doping and above. Raman spectra showed the characteristic mode of the wurtzite structure of ZnO nanoparticles with a vibration assigned to the bound of Co with the donor defects at high doping level of (Sm, Co). The spherical morphology of pure ZnO is transformed into nanorods as the concentration of Sm3+ and Co2+ increases. From EDX spectra, it was shown that all samples exhibit an excellent compositional homogeneity that verifies the Sm and Co presence as real dopants in ZnO crystalline structure. FTIR spectra show one discrete peak at 417 cm−1 with another broad peak at 568 cm−1corresponding to Zn–O stretching, which confirms the formation of the wurtzite structure of the samples. Photoluminescence studies reveal the existence of minor defects in the co-doped samples. The study proposes the suitable use of the samples in the high-efficiency UV light-emitting devices due to the intense UV peaks compared with the lower visible peaks. The excitation dependent PL spectra demonstrated a redshift with increasing the excitation wavelength accounting for the distribution of energetic species in the ground state. The DC electrical conductivity is enhanced with (Sm, Co) co-doping of x = 0.1 due to the formation of thermally activated donor levels.

Magnetic core–shell CoFe2O4@ZnO nanoparticles have been successfully synthesized by using coprecipitation method to provide easy separated nanomaterials and high photocatalytic activity performance. Core–shell nanoparticles with various CoFe2O4-to-ZnO molar ratio (1:2, 1:3, 1:4, 1:5) have been investigated over x-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectroscopy, and vibrating sample magnetometer. XRD spectra confirm the cubic spinel ferrite phase structure of CoFe2O4 and the hexagonal wurtzite phase of ZnO. The crystallite size is found within the range of 14.9–20.6 nm. TEM measurement confirms the good crystallinity of the samples. The magnetic hysteresis shows that CoFe2O4@ZnO has high saturation magnetization of about 30 emu g−1 and coercivity of about 300 Oe. Photocatalytic investigation was carried out using methylene blue (MB) under UV irradiation. Our result yields the enhancement of MB degradation as ZnO content increases. The maximum photodegradation achieved by the core–shell nanoparticles is 57.2%, 60.5%, 65.5%, and 78.3% for molar ratio of 1:2, 1:3, 1:4, and 1:5, respectively. The enhancement of MB degradation can be attributed to the formation of internal structure between CoFe2O4 and ZnO in the form of heterojunction structure. The magnetic properties of core–shell lead to the easy separation between the magnetic core–shell nanoparticles and the final degraded solution by permanent magnet.

Zn1−xSmxO nanoparticles, with 0.00 ≤ x ≤ 0.10, were prepared using chemical co-precipitation method. The structure and morphology of the obtained samples were characterized using x-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. However, the mechanical properties were investigated via digital Vickers microhardness tester. Vickers microhardness measurements were carried out at different applied loads, varying between 0.5 and 10 N at dwell time 60 s on pressed discs of average thickness 3 mm. Hv decreased as the Sm-content increased up to 0.02 and then it increased for higher concentrations. Whereas, it increased as the applied load increased, revealing that the samples exhibited a reverse indentation size effect (ISE). The microhardness measurements were interpreted using various models such as Meyer’s law, Hays and Kendall (HK) approach, elastic/plastic deformation (EPD), proportional specimen resistance (PSR) and the indentation-induced cracking (IIC). Mechanical parameters such as Young’s modulus (E), yield strength (Y), fracture toughness (K) and brittleness index (B) were calculated as a function of x. The most adequate model for the true microhardness of these samples is IIC. It was found that the addition of Sm content enhanced the mechanical properties of the prepared samples after x = 0.02. Dielectric measurements were used to compute different parameters such as real and imaginary parts of the complex permittivity, dielectric loss (tan δ) and ac conductivity (σ ac).

The quest for eco-friendly synthetic routes for the development of multifunctional nanoparticles for biomedical applications has reinforced the use of plant extracts as replacement solvents. Amongst the various nanoparticles, ZnO nanoparticles have emerged as a preferred candidate for various biological applications. In this study, ZnO nanoparticles were successfully synthesized by the solvothermal method using Sutherlandia frutescens extract. The morphological, structural, functional properties, elemental mapping and mass to charge ratio analysis were confirmed by TEM, SEM, SAED, FTIR, EDS and LCMS techniques. The ZnO nanoparticles exhibited a spherical morphology with a particle size distribution ranging from 5–25 nm. FTIR corroborated the formation of these nanoparticles with the ZnO peak identified in the fingerprint region. FTIR further showed the introduction of the phytochemical functional groups found in plants that were also confirmed on the Sf ZnO nanoparticles. The presence of bioactive molecules extracted from the plants were tested using wet chemistry and identified by LCMS. EDS analysis exhibited strong ZnO peaks which were verified by their elemental mapping using the same technique. Sf ZnO nanoparticles displayed exceptional biomedical activity with an antiproliferative effect of 93% against human lung cancer cells (A549) owing to the phytochemicals obtained from the Sutherlandia frutescens plant extract. These nanoparticles were also potent against gram-negative (Escherichia coli, Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus, Enterobacter faecalis) strains using model pollutants and real water pollutants.

Zinc oxide (ZnO) nanoparticles (NPs) have a wide range of biomedical applications. Present study demonstrates the new methodology in sol-gel technology for synthesizing Polyethylene glycol (PEG) ca ...

ZnO nanoparticles were synthesized using the sol–gel method with a variation on the sol aging time and refined structural data were taken to simulate the synthesized sample in a first-principles calculation. The ZnO nanoparticles aged at 36 h and showed profound properties with high crystallinity and good visual fit in a Rietveld analysis. Optical analysis revealed only small variation in energy band gap for all samples, ranging between 3.08–3.12 eV, with the presence of oxygen vacancy defects. In first-principles calculation, several exchange-correlation functionals, including LDA, GGA-PBE, GGA-PBESol, LDA + U, GGA-PBE + U and GGA-PBESol + U, were tested to converge with the lowest optimized lattice deviation. GGA-PBE + U (U d,Zn = 10 eV and U p,O = 6.1 eV) showed the lowest lattice deviation and reproduced the experimental band gap. The ZnO supercell structure with an oxygen vacancy showed that a defect state appears in the valence band and acts as a deep donor.

Diabetes mellitus is the most common endocrine disorder due to carbohydrate metabolism. Also, zinc and its supplements have been used in Indian traditional medicines for treating urinary tract infections. In this work, an attempt has been made to compare the properties of 'Yashadha Bhasma' a traditional ayurvedic ZnO supplement for diabetic treatment with the laboratory-synthesized ZnO nanoparticles. The nano-sized ZnO particles are synthesized using co-precipitation method and calcined at 400 °C for further purification. Confirmation of ZnO and presence of Ca and K elements additional to Zn in Yashadha Bhasma is confirmed from XPS. The morphology of ZnO is found to be spherical with average diameter of 15 nm. TEM results show that ZnO rods of Yashadha Bhasma are porous and non-uniform. Glucose degradation studies revealed good performance with ZnO nanoparticles with 80% degradation occurring within 15 min itself. Antibacterial studies also performed well establishing efficacy of ZnO nanoparticles against both gram-positive and gram-negative bacterial strains, thereby establishing suitable material for treating diabetes mellitus and also curing bacterial wound infections arising due to diabetes mellitus.

ZnTiO3-implanted ZnO nanoparticles were prepared by sol–gel method employing polyethylene glycol (PEG) 4000 and 20 000. The high resolution transmission electron micrographs, selected area electron diffraction pattern, energy dispersive x-ray spectra and powder x-ray diffractograms show the prepared materials as core/shell nanoparticles. Increase of the molecular mass of PEG decreases the d-spacing in ZnO of ZnTiO3-implanted ZnO and pristine ZnO nanoparticles. The charge transfer resistances of ZnTiO3-implanted ZnO nanoparticles are larger than those of pristine ZnO and precursor ZnTiO3 nanoparticles. The optical properties of ZnTiO3/ZnO nanoparticles are similar to those of pristine ZnO nanoparticles. The photocatalytic activity of ZnO is enhanced by the presence of ZnTiO3 core in the ZnO lattice. The bactericidal activity of core/shell ZnTiO3/ZnO nanoparticles is not less than that of ZnO nanoparticles.