Concentration Of Copper Nanoparticles Research Articles

Experimental heat transfer studies on copper nanofluids in a plate heat exchanger

The objective of the present work is to study the influence of copper nanoparticle concentration on heat transfer performance of a mixed base fluid. In the present study, the performance of copper nanoparticles in ethylene glycol (eg) + propylene glycol (pg) + water (W) base fluid was analyzed in the chevron- type plate heat exchanger. The sol-gel method was used to prepare copper nanoparticles (100 nm), dispersed in two different mixed base fluids of volume fractions 5%EG + 5%PG + 90%W and 15%EG + 5%PG + 80%W. Experiments were performed by varying the nanoparticle concentration from 0.2 to 1.0 vol.%. Three different hot fluid inlet temperatures were used (55, 65 and 75 ?C). It is revealed from the study that the rate of heat transfer increased significantly with the mixed base fluid. Result shows that at 75 ?C, 9 and 14.9% enhancement in the Nusselt number is obtained for 5%EG + 5%PG + 90%W and 15%EG + 5%PG + 80%W base fluid, respectively, for the nanoparticle concentration of 1%.

Antimicrobial Effect of Copper Nanoparticles Synthesized by Chemical Method

Copper nanoparticles were synthesized by chemical reduction of copper sulphate pentahydrate with sodium borohydride at ambient temperature in presence of PEG (Polyethylene Glycol) as protective agent and ascorbic acid as antioxidant. The synthesized copper nanoparticles were characterized by FT-IR to determine the presence of different functional groups attached to copper nanoparticles. Their optical property was determined by UV-Vis absorption spectrum where the peak was observed at 320 nm. The crystalline structure and surface morphology of copper nanoparticles were investigated by XRD and SEM respectively. The average crystalline size of nanoparticles calculated by Debye Scherer formula was found to be less than 10 nm having cubical shape. Microbial investigations by macro broth dilution, growth kinetics analysis and disc diffusion method confirmed antimicrobial nature of copper nanoparticles. The study reveals that concentration of copper nanoparticles at 128 ppm shows bacteriostatic effect. Their anti fungal effect was evaluated by testing against Alternaria species. The maximum inhibitory effect was found when copper nanoparticle concentration was 400 ppm or more.
 Int. J. Appl. Sci. Biotechnol. Vol 7(4): 421-428

Heat flux and convective boundary influence on nanofluid-filled cavity

Electronic devices release heat to the atmosphere from the walls, and system miniaturisation results in exponential increase in the heat associated with these high-heat-generating/electronic devices. To analyse this numerically, heat-flux and convective types of boundary condition are considered at the walls, which are the most realistic boundary condition type. In present work, the physical model consists of nanofluid inside an enclosure with one side subjected to constant heat-flux and the other sides exposed to convective boundaries, is solved. The nanofluid is completely confined within the enclosure and flows due to natural convection. Considering the heat-flux varying from 100 W/m2 to 10 kW/m2, three (Ra) Rayleigh numbers are calculated. Results are validated with experimental results also. Results show that increasing Ra and copper nanoparticle concentration results in strengthening the heat transfer and average Nusselt number. Results also show that the thermal boundary layer thickness increases with aspect ratio (AR). Streamline contours show that natural convection strength is higher for low ARs compared to high ARs. For a low Ra (2 × 104), viscosity model is more sensitive than the thermal conductivity model, and for high Ra (2 × 106), the thermal conductivity model is more sensitive than the viscosity model.

Impact of Copper Nanoparticle Addition on Thermo Physical Properties of Different Base Fluids

In the present work, thermo physical properties of different base fluids (Water, Ethylene Glycol, Propylene Glycol) by suspending various concentrations of copper nanoparticle was evaluated. Initially copper based nanofluid was prepared by two-step method and the concentration of copper nanoparticle was varied at 0.15, 0.2, 0.25 and 0.3 volume. %. The effect of copper nanoparticle concentration on thermo physical properties was evaluated. The result shows that the density, thermal conductivity and viscosity of all the chosen base fluids (Water, Ethylene Glycol, and Propylene Glycol) were increased; however the specific heat of these base fluids decreases while increasing the copper nanoparticle concentration.

Evacuated tube solar collector performance using copper nanofluid: Energy and environmental analysis

The effect of metallic copper nanoparticles on the thermal efficiency of an evacuated tube solar collector was studied. Different volume concentrations of copper nanoparticles e.i. 0.01%, 0.02% and 0.03% were examined to explore the effect of nanoparticles on evacuated solar collector performance. The tests were performed at three volume flow rates of 0.6 L/min, 0.7 L/min and 0.8 L/min. The results demonstrate a 50% increase in the output temperature. Also, the heat energy incremented from 417 W to 667 W, which is equivalent to 34% area reduction for the same energy production. The remarkable enhancement in the heat removal factor to reach a value of 0.97. Copper nanoparticles played a significant role to increase both the absorbed energy and the removal energy parameters. Their maximum values were found for a volume concentration of 0.03% and at the volume flow rate of 0.8 L/min to be 0.83 and 21.66, respectively. Finally, environmental analysis is carried out to find the role of copper nanoparticles in CO2 reduction. The comparison between current results with reported results in the literature for other types of nanoparticles, show the high potential of copper nanoparticles for solar collector applications.

Antibacterial Activities of Copper Nanoparticles in Hybrid Microspheres.

Active hybrid microspheres were prepared by blending aqueous solutions of gelatine and chitosan with different concentrations of copper nanoparticles (0) (CuNPs) using emulsion-based crosslinking synthesis to obtain hybrid microspheres. The incorporation of CuNPs slightly affected the physical and chemical properties of the films. Microscopic surface structure (SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis confirmed the presence of elemental copper and the crystalline structure of the CuNPs in the hybrid matrix. The surface properties of CuNPs were studied by XPS analyses. The antimicrobial activity of CuNPs coated with chitosan (QO)/gelatine (GE) compared to the QO/GE matrix alone was investigated, using the agar diffusion and culture medium methods in Mueller-Hinton. The evaluation was performed using the Gram-negative bacterium E. coli and the Gram positive bacterium E. faecalis. The investigated microspheres showed antimicrobial activity. Hybrid microspheres with 40 mg of Cu, evaluated in liquid medium, inhibited the growth of E. coli by 56% and of E. faecalis by 40% compared to the matrix hybridised alone; in solid medium, the inhibition was 2.5-fold and 2.6-fold, respectively. Thus, these microspheres are a promising material for applications with medical uses.

Optimization and Application of Bioflocculant Passivated Copper Nanoparticles in the Wastewater Treatment.

Nanotechnology offers a great opportunity for efficient removal of pollutants and pathogenic microorganisms in water. Copper nanoparticles were synthesized using a polysaccharide bioflocculant and its flocculation, removal efficiency, and antimicrobial properties were evaluated. The synthesized nanoparticles were characterized using thermogravimetry, UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction, scanning electron microscope (SEM), and transmission electron microscope (TEM). The highest flocculation activity (FA) was achieved with the lowest concentration of copper nanoparticles (0.2 mg/mL) with 96% (FA) and the least flocculation activity was 80% at 1 mg/mL. The copper nanoparticles (CuNPs) work well without the addition of the cation as the flocculation activity was 96% and worked best at weak acidic, neutral, and alkaline pH with the optimal FA of 96% at pH 7. Furthermore, the nanoparticles were found to be thermostable with 91% FA at 100 °C. The synthesized copper nanoparticles are also high in removal efficiency of staining dyes, such as safranin (92%), carbol fuchsine (94%), malachite green (97%), and methylene blue (85%). The high removal efficiency of nutrients such as phosphate and total nitrogen in both domestic wastewater and Mzingazi river water was observed. In comparison to ciprofloxacin, CuNPs revealed some remarkable properties as they are able to kill both the Gram-positive and Gram-negative microorganisms.

Optimization of copper nanoparticles synthesized by pulsed laser ablation in distilled water as a viable SERS substrate for karanjin

A comprehensive study on the factors affecting the surface enhanced Raman scattering capability of copper nanoparticles for furanoflavonoid, karanjin is reported. The copper nanoparticles have been synthesized by pulsed laser ablation of a copper target immersed in distilled water. An interesting trend of increase followed by a decrease in the Raman enhancement with the decrease in concentration of copper nanoparticles is observed. This variation is attributed to the count of number of nanoparticles present around karanjin. The optimum concentration of copper nanoparticles for maximum SERS intensity of nanoparticle treated karanjin is found to be approximately 0.291 mg/mL. This optimum concentration corresponds to the sample having an average particle size of ∼11 nm. There is a fall in the enhancement for smaller nanoparticles of average size ∼7 nm as well as larger nanoparticles of ∼20 nm. The observations have been explained on the basis of the electromagnetic enhancement due to the localized surface plasmons of the copper nanoparticles. The role of aggregation amongst the nanoparticles and also the degree of oxidation of the nanoparticles in controlling the SERS intensity is discussed.

Influence of the concentration of copper nanoparticles on the thermo‐mechanical and antibacterial properties of nanocomposites based on poly(butylene adipate‐co‐terephthalate)

Poly(butylene adipate‐co‐terephthalate) (PBAT) was mixed with copper nanoparticles (Cu‐NPs) in concentrations of 1%, 3%, and 5% with particle size between 100 nm and 200 nm by the melting method. A morphological, thermal, and structural characterization of the nanocomposites (NCs‐PBAT/Cu) was performed to analyze the effect of the Cu‐NPs on the polymer chains, as well as to explain the influence on their crystallinity, and its influence on the thermomechanical and antibacterial properties. The percentage of crystallinity (Xc) increased 6.7% to 9.5% with the amount of Cu‐NPs in the matrix. E‐modulus was slightly improved from 84.04 to 87.7 MPa, in the same way the degradation temperature (Td) of the PBTA was improved from 420.7°C to 427.2°C for 5% loading of Cu‐NPs. In contrast, ΔHm decreased from 12.50 to 6.96 J/g, indicating that there was no significant modification of the PBAT chain, mainly by heterogeneous nucleation in the presence of Cu‐NPs, which act as a heat barrier. No blue or red shifts we observed in the nanocomposites Fourier transform infrared (FTIR) spectra, indicating there is no effective interaction between PBAT and Cu‐NPs. The nanocomposites showed excellent antibacterial properties inhibiting 100% of the strains Enterococcus faecalis, Streptococcus mutans, and Staphylococcus aureus, at 2 hours of treatment. For more resistant strains such as Acinetobacter baumannii, the NCs‐PBAT/Cu did not show antibacterial activity at any time of treatment. POLYM. COMPOS., 40:1870–1882, 2019. © 2018 Society of Plastics Engineers

Therapeutic Potential of Quercetin on Biochemical Deteriorations Induced by Copper Oxide Nanoparticles

Objective: The current research is designed to evaluate copper oxide nanoparitcles (CuO NPs) toxicity on HCT116 in vitro as well as in vivo on liver paraoxanse 1 (PON1 ) activity and serum B-cell lymphoma -2 (BCl2) in rats.
 Materials and Methods: The toxicological role of CuO-NPs on the liver was indicated through intraperitoneal injection of 3 and 50 mg/kg of CuO-NPs (size >20 nm) in female rats for 7 days. The effects of NPs were examined by demonstrating serum levels of antiapoptotic marker (BCl2) and antioxidant enzyme PON1 .Flavonoids quercetin (que) was administered orally to intoxicated rats at the dose of 200 mg/kg for 30 consecutive days.
 Results: In vitro study showed 100% death of HCT116 cells up to 12.5 ug/ml. The current results declared obvious PON1 inhibition and BCl2 in CuO-NPs intoxicated rats. Also, the results of this study indicated that the two concentrations of copper nanoparticles induced toxicity, while attenuation in antioxidant status and antiapoptotic marker was detected upon treated intoxicated rats with que.
 Conclusion: It is evident that these nanoparticles cannot be used for human purposes because of their toxicity caused by oxidative stress implicated in liver toxicity by CuO-NPs. This study also declared that que is an effective free radical scavenger and could consider a potential nutraceutical for liver toxicity.

Influence of Iron, Zinc, and Copper Nanoparticles on Some Growth Indices of Pepper Plants

This paper presents the results of studies on the effect of iron, zinc, and copper nanoparticles (NPs) introduced into a Murashige and Skoog (MS) nutrient medium instead of metal salts on the chlorophyll content in leaves and the length and activity of the roots of the Capsicum annuum pepper plants grown under aseptic conditions. It is shown that the length of the roots of plants grown on a nutrient medium with metal nanoparticles, depending on the dose of NPs and element, is 7‒118% higher than in plants grown on a standard nutrient medium. The activity of the roots of the test plants is 18‒98% higher than the activity of plant roots from the control group. The chlorophyll content in the leaves of pepper grown on a medium with iron and copper nanoparticles is 3‒59% higher than the amount of chlorophyll in plants grown on a standard MS medium. The effective concentrations of iron NPs (3.0, 0.3, and 0.06 mg/L) introduced into the nutrient medium are 1.9, 18.7, and 93.3 times lower, respectively, than the concentration of iron in the ionic form (in terms of metal) contained in standard MS medium; the concentration of zinc NPs (0.4, 0.08, and 0.016 mg/L) is 4.9, 24.5, and 122.5 times less than the concentration of zinc ions in terms of metal in MS; and the concentration of copper NPs (0.004, 0.0008, and 0.00016 mg/L) is 1.6, 8.0, and 40.0 times less than the concentration of copper in terms of copper ions in the standard MS medium.

Synthesis and Thermomechanical Characterization of Nylon 6/Cu Nanocomposites Produced by an Ultrasound‐Assisted Extrusion Method

A nylon 6 nanocomposite with copper nanoparticles processed by ultrasound‐assisted extrusion was prepared at concentrations between 0.01 and 0.50 wt.%, and its thermal and mechanical properties were determined. The presence of the crystalline phase α (α1 and α2) in the polymer matrix was confirmed by X‐ray diffraction, and the presence of the α2 phase showed a greater increase than the α1 phase as a function of the copper nanoparticle concentration. This process was attributed to secondary crystallization. Furthermore, it was determined that the chemical composition of the nanoparticles is a blend of metallic copper and cupric oxide. The formation of copper nanowires was observed by scanning electron microscopy, and the concentration of 0.10% exhibited the best dispersion in comparison with the other concentrations. The melting temperature of the nanocomposites underwent a slight decrease in comparison with the nylon 6, while thermal stability, crystallization temperature, and crystallinity were increased in relation to the pure polymer. This behavior is attributed to an efficient dispersion of the nanoparticles and to their functionality as crystal nucleation sites. For the 0.10% concentration nanocomposite, higher mechanical properties were obtained; tensile strength increased by 8.9%, and the tensile modulus increased by 25.4%; as a consequence, elongation at break was 62% less than that of the polymer matrix.

CELLULOSIC TEXTILE MATERIALS WITH ANTIBACTERIAL PROPERTIES MODIFIED WITH COPPER NA-NOPARTICLES

The paper presents data on the development of cellulosic textile materials with increased antimicrobial properties using copper nanoparticles. Synthesis of copper nanoparticles was carried out by simple chemical reduction of an aqueous solution of copper using ascorbic acid as a reducing agent. The influence of the concentration of copper, a reducing agent, and a stabilizer on the synthesis of copper nanoparticles was studied.A composition based on polyvinyl alcohol and copper nanoparticles was developed to impart enhanced antimicrobial properties to cellulosic textile materials. The results of the studies showed that a significant growth of bacteria was observed in the control sample (untreated fabric), the amount of mesophilic aerobic and facultative anaerobic microorganisms (Staphylococcus aureus) decreased with increasing concentrations of copper nanoparticles, antibacterial properties increased. Modified by the proposed method cellulosic textile materials showed high resistance to the action of microorganisms and can be used for the production of sanitary and hygienic textile products.

Optimization of coating solution for preparation of antibacterial copper-polyethylene nanocomposite

Polyethylene film was coated with copper nanoparticles and its antibacterial properties were investigated. To make nanocomposite film, the solutions containing the copper nanoparticles were prepared using polyamide resin in six different concentrations of copper nanoparticles (1%, 2%, 3%, 5%, 7% and 10 wt%). Corona discharge was used to improve the nonpolar surface of polyethylene and prepare it for coating. Corona discharge was carried out in 5 min with power of 10 000 W. Characterisation of nanoparticles and the coated surface were performed using dynamic light scattering (DLS), x-ray diffraction (XRD) and scanning electron microscope (SEM). The antibacterial activity of polyethylene-copper nanocomposite against two type of bacteria including gram-negative Escherichia coli and gram-positive Staphylococcus aureus was measured by disc-diffusion method. In addition, the optimum concentration of copper nanoparticles was determined about 5 wt%. The current technique of coated film preparation reduces the amount of required nanoparticles which finally offers lower production cost.

Mechanical and microbiological properties and drug release modeling of an etch-and-rinse adhesive containing copper nanoparticles

ObjectivesTo evaluate the effect of addition of copper nanoparticles (CN) at different concentrations into a two-step etch-and-rinse (2-ER) adhesive on antimicrobial activity (AMA), copper release (CR), ultimate tensile strength (UTS), degree of conversion (DC), water sorption (WS), solubility (SO), as well as the immediate (IM) and 1-year resin–dentin bond strength (μTBS) and nanoleakage (NL). MethodsSeven adhesives were formulated according to the addition of CN (0, 0.0075, 0.015, 0.06, 0.1, 0.5 and 1wt%) in adhesive. The AMA was evaluated against Streptococcus mutans using agar diffusion assay. For CR, WS and SO, specimens were constructed and tested for 28 days. For UTS, specimens were tested after 24h and 28 days. For DC, specimens were constructed and tested after 24h by FTIR. After enamel removal, the ER was applied to dentin. After composite resin build-ups, specimens were sectioned to obtain resin–dentin sticks. For μTBS and NL, specimens were tested after 24h and 1-year periods. All data were submitted to statistical analysis (α=0.05). ResultsThe addition of CN provided AMA to the adhesives at all concentrations. Higher CR was observed in adhesives with higher concentration of CN. UTS, DC, WS and SO were not influenced. For μTBS an increase was observed in 0.1 and 0.5% copper group. For NL, a significant decrease was observed in all groups in comparison with control group. After 1-year, no significant reductions of μTBS and no significant increases of NL were observed for copper containing adhesives compared to the control group. SignificanceThe addition of CN in concentrations up to 1wt% in the 2-ER adhesive may be an alternative to provide AMA and preserve the bonding to dentin, without reducing adhesives’ mechanical properties evaluated.

Copper nano-particles for antibacterial properties of wrinkle resistant cotton fabric

In this research cotton fabrics were treated with different concentrations of maleic acid (MA), as cross-linking agent, and sodium hypophosphite (NaH2PO2) as the catalyst, with constant concentration of copper nano particles by two methods: Separately and simultaneously. Laundering test was done due to the standard test method for determination of durability of the treatment. Some physical properties such as crease recovery angle and weight gain were examined. The maleic acid treated cotton fabrics were dyed with methylene blue dye. Reflective spectrophotometer was used to determine methylene blue dye absorption. FTIR/ATR analysis was done for investigation of chemical structure, and atomic absorption spectroscopy was used for determining of copper ions contents. The antibacterial properties were investigated by using AATCC-100 standard test method. The results showed that the crease recovery angle, weight and methylene blue dye absorption were increased by increasing the concentration of maleic acid. By comparing the results of separate and simultaneous copper nano particles treatment, in simultaneous method, antimicrobial properties, copper ion absorption and weight gain reduced and washing fastness was increased. Whereas by Separate method, antimicrobial properties, copper absorption and weight gain were increased.

Antibacterial activity of copper nanoprticles and Watercress (Nasturtium officinale R. Br.) extracts

This study was aimed to detect the antibacterial activity of N. officinale leaves water and ethanol extract alone or mixed with a specific concentrations of copper nanoparticles (800mg/L). Studied Bacterial samples consist of two gram-positive bacteria (Escherichia coli and Pseudomonas aeruginosa) and two gram-negative bacteria (Staphylococcus aureus and Streptococcus pyogenes). Results showed that there was a significant increase in the mean inhibition zone at 1:1 (v/v) of 1.0mg/10ml copper nanoparticles and water leaves extract (J) and 1:1 (v/v) of 0.5mg/10ml mg/10ml copper nanoparticles and ethanol leaves extract (F) compared with 0.5mg/10ml leaves water extract (B) and 0.5mg/10ml leaves ethanol extract (C), but there was no significant differences obtained between the types of treatments and the standard antibiotic that used as control (250 mg/10ml Cefotaxime), the highest mean inhibition zone was recorded in Staphylococcus aureus bacteria compared with other bacterial species. The interaction revealed that the highest mean inhibition zone obtained in 1:1 (v/v) of 1.0mg/10ml copper nanoparticles and water leaves extract (J) in Staphylococcus aureus bacteria and the lowest mean inhibition zone observed in 1.0mg/10ml copper nanoparticles (I) in Pseudomonas aeruginosa bacteria while mean inhibition zone significantly increased in E. coli bacteria at 1:1 (v/v) of 0.5mg/10ml mg/10ml copper nanoparticles and ethanol leaves extract (F), 1:1 (v/v) of 1.0mg/10ml copper nanoparticles and water leaves extract (J), and 1:1 (v/v) of 1.0mg/10ml copper nanoparticles and ethanol leaves extract (K). No significant differences recorded in the mean inhibition zone of Pseudomonas aeruginosa and Staphylococcus aureus bacteria in various treatments. Asian Australas. J. Biosci. Biotechnol. 2016, 1 (3), 564-571

Effect of copper nanoparticle aggregation on the thermal conductivity of nanofluids

The thermal conductivity of water and glycerol is investigated via the transient hot wire method by adding small amounts of copper nanoparticles to solutions. At a 0.2% copper nanoparticle concentration, the thermal conductivity coefficient rises to 25% for the Cu + glycerol system, and to 35% for Cu + water system. A mechanism and mathematical model for describing the nanoparticle aggregation effect on the thermal properties of nanofluids are proposed, based on an analysis of the accumulated experimental data. It is shown that the enhancement of nanofluid thermal conductivity at low nanoparticle concentrations is directly proportional to their volume fraction and thermal conductivity coefficient, and (in accordance with the literature data) is inversely proportional to the radius and the aggregation ratio. The proposed model describes the existing experimental data quite well. The results from this work can be applied to the rapid cooling of electronic components, in the power engineering for ensuring the rapid and effective transfer of thermal energy in a nuclear reactor, and in the oil industry for thermal stimulation.

Assessment of antifungal effects of copper nanoparticles on the growth of the fungus Saprolegnia sp. on white fish (Rutilus frisii kutum) eggs

This study was conducted to evaluate the in-vitro effects of copper nanoparticles on the growth of the fungus Saprolegnia sp. isolated from white fish (Rutilus frisii kutum) eggs. The antifungal effects were measured by determining the minimum lethal concentration of copper nanoparticles on Saprolegnia sp. in yeast extract glucose chloramphenicol (YGC) agar at 25°C. Saprolegnia grown in YGC agar without added copper nanoparticles served as negative controls. Our study showed that copper nanoparticles at a minimum concentration of 10ppm have antifungal effects on Saprolegnia sp. The antifungal effects of copper nanoparticles are positively correlated to both concentration and time of exposure. This study showed that the antifungal properties of copper nanoparticles make it a good alternative to malachite green, which is carcinogenic.

Ultrasonic technique for concentration characterization of copper nanofluids synthesized using μ-EDM: A novel experimental approach

Colloidal suspensions of copper nanoparticles were synthesized using a developed micro-electrical discharge machining (μ-EDM) method. Average size of the particles dispersed in de-ionized (DI) water is found to be in sub-micron size and that in DI water with stabilizers PolyVinyl Alcohol (PVA) and PolyEthylene Glycol (PEG) is less than 10nm. The present paper is focused on an exceptional technique using ultrasound which is used for concentration characterization of copper nanofluids in-line. The mass concentration of copper nanoparticles dispersed in suspension media is determined by Urick and Ament's relationship, and the results are found to be 7wt%, 7wt% and 6wt% in Cu-DI water, Cu-DI water+PVA and Cu-DI water+PEG nanofluids respectively. This study shows that the ultrasonic velocity in Cu-nanofluids increases as compared to the suspension media. However, it was observed that the nanoparticles in suspension media of determined concentrations alter the ultrasonic velocity by affecting the acoustic time of flight. The results demonstrate that due to strong particle–particle interaction conferred by the aggregation of particles, the ultrasonic velocity in the Cu-DI water nanofluid is found to be decreased as compared to the PVA and PEG nanofluid samples. Further, due to the reduction in size of the particles generated and less concentration in DI water+PEG mixture, the ultrasonic velocity in the Cu-DI water+PEG nanofluid is found to be decreased as compared to that in the PVA nanofluid sample.