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Nanopesticides have been recently introduced as novel pesticides to overcome the drawbacks of using traditional synthetic pesticides. The present study evaluated the acaricidal activity of Copper/Graphene oxide core-shell nanoparticles against two tick species, Rhipicephalus rutilus and Rhipicephalus turanicus . The Copper/Graphene oxide core-shell nanoparticles were synthetized through the solution plasma (SP) method under different conditions. The nanoparticles synthesized at 180 W and 45 min were highly toxic to Rh. rutilus and Rh. turanicus , with 50% lethal concentration (LC 50 ) values of 248.1 and 195.7 mg ml −1 , respectively, followed by those which were synthesized at 120 W/30 mins (LC 50  = 581.5 and 526.5 mg ml −1 ), 120 W/15 mins (LC 50  = 606.9 and 686.7 mg ml −1 ), and 100/45 mins (LC 50  = 792.9 and 710.7 mg ml −1 ), after 24 h of application. The enzyme assays revealed that 180 W/45 min treatment significantly inhibited the activity of acetylcholinesterase (115 ± 0.81 and 123 ± 0.33 U/ mg protein/min) and superoxide dismutase (290 ± 0.18 and 310 ± 0.92 U/ mg protein/min) in Rh. rutilus and Rh. turanicus , respectively, as compared with the negative control. The results also revealed a significantly increased catalase activity (895 ± 0.37 and 870 ± 0.31 U/ mg protein/min) in Rh. rutilus and Rh. turanicus , respectively. The above results indicated that Copper/Graphene oxide core-shell nanoparticles could be a promising alternatives for the management of ticks.

In this study, the copper-graphene oxide composites were prepared using low sintering temperature to investigate the effect of various mesh sizes of GO on Cu-GO composites. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman were conducted to elaborate the microstructure, diffraction pattern and disorder in the powders as well as bulk composites. Transmission electron microscopy (TEM) analysis was also carried out to further study the microstructural analysis of composites at the nano-scale level. By changing the mesh sizes of GO from lower to higher level, the tensile strength and hardness of Cu-GO composites were significantly enhanced due to better mixing of GO with higher mesh size. A fractograph analysis was also examined in detail to investigate the effect of various mesh sizes of GO on Cu-GO.

Dental caries is a biofilm-dependent disease that largely relies on the ability of to synthesize exopolysaccharide matrix. Graphene oxide-based metal nanomaterials, as the derivatives of graphene, are potent agents against pathogens by their impressive antibacterial and anti-biofilm biofunctions. Previously, we fabricated the novel graphene oxide-copper nanocomposites (GO-Cu), maintaining a long-term release of copper nanoparticles. Here, the biofunctionalization of GO-Cu nanocomposites against cariogenic is investigated. Growth curve observation and colony forming units counting were applied to detect the antibacterial effect of GO-Cu nanocomposites on . Scanning electron microscopy and the crystal violet assay were used to detect nanocomposite effects on biofilm forming ability. The production and distribution of exopolysaccharides within biofilm was analyzed and the expression of genes required for biofilm formation was explored. Moreover, the regulatory landscape of GO-Cu nanocomposites on pathogenicity was probed. It has been found that GO-Gu nanocomposites were antibacterial to and 10 μg/mL GO-Cu nanocomposites could inhibit the bacteria bioactivity instead of killing them. The biomass of biofilm was significantly reduced when treated with 10 μg/mL GO-Cu nanocomposites. Also, 10 μg/mL GO-Cu nanocomposites could alter the biofilm architecture and impair exopolysaccharides production and distribution, and dysregulated the expression of exopolysaccharide-associated genes. In all, we found low-dose GO-Cu nanocomposites could disrupt exopolysaccharide matrix assembly and further impair optimal biofilm development with minimal cytotoxicity. Therefore, GO-Cu nanocomposites can open up a new avenue for the development of alternative anti-caries biomaterials.

This study investigated the effects of microwave sintering on the microstructures and properties of copper-rGO composites. Graphene oxide was coated onto copper particles by wet ball milling, and copper-rGO composites were formed upon microwave sintering in an argon atmosphere. Scanning electron microscopy was then used to observe the mixing in the ball-milled composite powder, and the morphology of the bulk composite after microwave sintering. Raman spectra revealed how graphene oxide changed with ball milling and with microwave sintering. The microhardness, electrical conductivity, and thermal conductivity of the composite were also measured. The results showed that graphene oxide and copper particles were well combined and uniformly distributed after wet ball milling. The overall microhardness of microwave-sintered samples was 81.1 HV, which was 14.2% greater than that of pure copper (71 HV). After microwave sintering, the microhardness of the samples in areas showing copper oxide precipitates with eutectic structures was 89.5 HV, whereas the microhardness of the precipitate-free areas was 70.6 HV. The electrical conductivity of the samples was 87.10 IACS%, and their thermal conductivity was 391.62 W·m−1·K−1.

The thermal performance enhancement of a vertical helical coil heat exchanger using distilled water-based copper oxide-graphene hybrid nanofluid has been analyzed experimentally. Accordingly, the focus of this study is the preparation of CuO-Gp (80-20%) hybrid nanoparticles-based suspensions with various mass fractions (0% ≤ wt ≤ 1%). The volume flow rate is ranged from 0.5 L·min−1 to 1.5 L·min−1 to keep the laminar flow regime (768 ≤ Re ≤ 1843) and the supplied hot fluid’s temperature was chosen to equal 50 °C. To ensure the dispersion and avoid agglomeration an ultrasound sonicator is used and the thermal conductivity is evaluated via KD2 Pro Thermal Properties Analyzer. It has been found that the increment in nanoparticles mass fraction enhances considerably the thermal conductivity and the thermal energy exchange rate. In fact, an enhancement of 23.65% in the heat transfer coefficient is obtained with wt = 0.2%, while it is as high as 79.68% for wt = 1%. Moreover, increasing Reynolds number results in a considerable augmentation of the heat transfer coefficient.

The fabrication of electrochemical sensor for the ultra-low-level detection and quantification of Imidacloprid (IMD) in soil is one of the major challenges in real-time analysis. Herein, a three-electrode system for sensing IMD at low levels has been developed using Cu–rGO nanofiber composite modified glassy carbon working electrode, Ag/AgCl reference and platinum wire counter electrodes. In the presence of IMD, a significant enhancement in voltammetric current responses were observed at 0.506, 0.375 and 0.181 V due to NO3-:N2,NO3:NO2-,NO3-:NH4 redox complexes. The developed sensor exhibited sensitivity of 0.325 µA µM−1 with the limit of detection, quantification and repeatability of 2.511 nM, 7.533 nM and 0.28 RSD% respectively. The fabricated sensor could detect IMD with swift response time of less than 5 s. Further, the fabricated electrode was successfully employed to quantify the levels of IMD in soil samples and the results are reported.

Sensing ability of carbon monoxide (CO) using poly-Si nanowires field effect transistors (FET) was evaluated in this thesis. The concentration of carbon monoxide (CO) is targeted at 4 ppm to distinguish between COPD patients and healthy people. Various phthalocyanine (PC) compounds were applied to modify the surface of poly-Si nanowires. The sensitivity and selectivity can be enhanced by the surface modified poly-Si nanowires. The enhancement can be attributed to the bonding properties between phthalocyanine compounds and carbon monoxide molecules. Besides, the relative humidity (RH) was taken into consideration when evaluated the sensing ability. The experimental results suggested that the electrical properties of the devices were in competition between water molecule and carbon monoxide. Finally, the surface modified poly-Si nanowires FETs was approved that they can be applied to detect low concentration of carbon monoxide at different RH. In particular, the electrical property of poly-Si nanowires FETs are