Concentration Of Nanoparticles Research Articles

Rheological behavior and solution pH response properties of nanoparticle-regulated low surface tension systems.

Regarding the rheological properties of fluids, certain nanoparticles can markedly modify the rheological behavior of low surface tension solutions by interacting with surfactant molecules. In this work, a low surface tension fluid with cetyltrimethylammonium chloride was prepared, and the silica nanoparticles were uniformly dispersed into it by ultrasonic dispersion. By adjusting the size, shape, and concentration of nanoparticles, the fluid behavior can be changed from Newtonian to non-Newtonian with finely tuned viscosity and characterized by a shear-thinning rheological behavior. In addition, this work explored how variations in environmental temperature and solution pH affect the rheological responses of the low surface tension suspension system. The experimental findings revealed that increasing the temperature substantially decreases the system's viscosity and induces a shear-thickening behavior. It is particularly significant that, under extreme pH conditions (either strongly acidic or alkaline), the viscosity of the nanoparticle suspensions was markedly enhanced at a particle concentration of 10 000 ppm. This interesting result coincided with a notable reduction in the zeta potential and an increase in the average particle size, suggesting an intensified aggregation of particles within the suspension system. A mechanism detailing the interaction between silica nanoparticles and surfactant micelles was proposed. This work indicates that the incorporation of nanoparticles into surfactant solutions offers a powerful approach to modulating fluid rheology across various conditions.

A promising eco-friendly and cost-effective photocatalytic rolled graphene oxide/poly(m-methylaniline) core-shell nanocomposite for antimicrobial action.

A new and innovative rolled graphene oxide (roll-GO)/poly-m-methylaniline (PmMA) core-shell nanocomposite has been successfully synthesized using an in situ polymerization technique. This eco-friendly and cost-effective material shows great promise due to its antimicrobial properties. The characterization of the nanocomposite involved X-ray diffraction and Fourier transform infrared spectroscopy to analyze its structure and functional groups, whereas scanning electron microscopy and transmission electron microscopy (TEM) were utilized to examine its morphology. TEM analysis revealed the formation of roll-GO, forming multi-walled tubes with inner and outer diameters of 50 and 70nm, respectively. Optical analysis demonstrated an enhanced bandgap in the nanocomposite, with bandgap values of 2.38eV for PmMA, 2.67eV for roll-GO, and 1.65eV for roll-GO/PmMA. The antibacterial efficacy of the nanocomposite was tested against Gram-positive bacteria, including Bacillus subtilis and Staphylococcus aureus, as well as Gram-negative bacteria such as Escherichia coli and Salmonella sp. The well diffusion method was used to determine the inhibition zones, revealing that the nanocomposite demonstrated broad-spectrum antibacterial activity against all the pathogens tested. The largest inhibition zones were observed for B. subtilis, followed by S. aureus, E. coli, and Salmonella sp. Notably, the inhibition zones increased when the samples were exposed to light compared to dark conditions, with increases of 33 and 18mm noted for B. subtilis. This enhanced activity under light exposure is attributed to the photocatalytic properties of the nanocomposite. The antibacterial mechanism is based on both adsorption and degradation processes. Moreover, antibacterial activity was found to increase with increasing concentrations of nanoparticles, ranging from 100 to 500ppm. This suggests that the nanocomposite has potential as an alternative to antibiotics, especially considering the growing issue of bacterial resistance. The promising results obtained from the inhibition zones make these nanocomposites suitable for various applications. Currently, the research team is working on the development of a prototype utilizing these antimicrobial particles within commercial bottles for sterilization purposes in factories and companies.

Characterization, impact and wear properties of treated and as-received graphene nanosheets reinforcement in epoxy resin composites

PurposeThis study aims to explore the enhancement of mechanical properties in epoxy resin composites through the incorporation of graphene nanoparticles, focusing on their impact and wear resistance. It investigates the role of graphene, both treated and untreated, as a reinforcing agent in composites, highlighting the significance of nanoparticle dispersion and surfactant treatment in optimizing mechanical performance.Design/methodology/approachEmploying a novel dispersion technique using a drawing brush, this research contrasts with traditional methods by examining the effects of graphene nanoparticle concentrations treated with surfactants – Polyvinylpyrrolidone (PVP) and Sulphonated Naphthalene Formaldehyde (SNF) – on the mechanical properties of epoxy resin composites. The methodology includes conducting a series of impact and wear tests to assess the influence of graphene reinforcement on the composites' performance.FindingsThe findings reveal a marked enhancement in the composites impact resistance and energy absorption capabilities, which escalate with an increase in graphene content. Additionally, the study demonstrates a significant improvement in wear resistance, attributed to the superior mechanical properties, robust interface adhesion and effective dispersion of graphene. The use of surfactants for graphene treatment is identified as a crucial factor in these advancements, offering profound insights into the development of advanced composite materials for diverse industrial uses.Originality/valueThis study introduces a unique dispersion technique for graphene in epoxy composites, setting it apart from conventional methods. By focusing on the critical role of surfactant treatment in enhancing the mechanical properties of graphene-reinforced composites, it provides a novel insight into the optimization of impact and wear resistance.

Enhancing Solar Absorption with Double-Layered Nickel Coatings and WS2 Nanoparticles on Copper Substrates

This study focused on the development and characterization of multi-layered nickel coatings doped with WS2 nanoparticles and electrodeposited on copper substrates. To enhance the solar collector’s performance by improving the solar radiation conversion into heat, two distinct undercoatings were evaluated, along with the incorporation of WS2 nanoparticles in the black nickel layer. X-ray diffraction (XRD) analysis revealed that the bright and dull nickel undercoatings consisted of metallic nickel, whereas the black coatings comprised amorphous nickel oxide, inferred to be Ni2O3 based on energy-dispersive X-ray spectroscopy (EDS) analysis. Scanning electron microscopy (SEM) analysis of the undercoatings and black nickel morphology showed a compact surface with a relatively homogenous microstructure composed of polyhedric grains, which was free of visible cracks or pinholes. The undercoating influenced the brightness, the reflectivity and the reflectance of the black nickel films, with the dull undercoated sample showing the most promising results, with a total absorbance of 0.94. The incorporation of WS2 nanoparticles induced the formation of cracks and increased the porosity of the black nickel film. With an appropriate content of WS2 nanoparticles and the use of a dull undercoat, these drawbacks can be avoided. Concerning the integration of WS2 nanoparticles, a minor decrease in the brightness of the black films and a subsequent increase in the total absorbance ultimately led to an enhancement of the conversion of solar energy into thermal energy.

Experimental investigation on spray cooling heat transfer properties of ethylene glycol-water-based nanofluids

Abstract Spray cooling is a practical solution for high heat flux heat dissipation problems. The spray cooling experiment was conducted with 50wt% ethylene glycol aqueous solution as the base liquid in this paper. The effects of the concentrations of copper nanoparticles, copper oxide nanoparticles, silica nanoparticles and surfactant Tween-20 on the heat transfer characteristics during spray cooling were investigated. The results showed that adding nanoparticles within a certain concentration range could enhance the effectiveness of spray cooling's heat transmission. Under the same conditions, adding copper nanoparticle has the best effect, followed by copper oxide nanoparticle, and silica nanoparticle has relatively poor effect. Among them, the heat transfer coefficient and heat flux of the nanofluid could be raised by 10.58% and 11.34% in comparison to the base liquid when the concentration of copper nanoparticles was 0.01wt%. As the concentration of nanoparticles rises higher, spray cooling's ability to transfer heat is hampered. Adding the surfactant Tween-20 could effectively improve the copper-water-ethylene glycol nanofluid's capacity for heat transmission. When the concentration is 3ppm, the heat transfer coefficient and heat flux of the nanofluid with Tween-20 were increased by 9.81% and 10.38% compared to the copper-water-ethylene glycol nanofluid.

Green synthesis of copper oxide nanoparticles using Rosmarinus officinalis leaf extract and evaluation of its antimicrobial activity

Due to the development of green technology, researchers are becoming more interested in low-cost, environmental eco-friendly methods for the synthesis of nanoparticles (Nps). In this work, Copper oxide nanoparticles (CuO Nps) were synthesized using a green synthesis technique, with Rosmarinus officinalis leaf extract acting as a capping and reducing agent. The as prepared the samples was characterized using UV-Visible Spectra (UV–VIS), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Scanning Electron Microscopy (SEM). The UV-Visible spectra result showed that strong absorption was observed for characteristic band of green synthesized CuO Nps and exhibit red shift as the weight fraction of CuO Nps increases. The XRD analysis confirmed the formation of CuO Nps, having a typical monoclinic structure with crystalline size ranging from 18 to 26 nm. From FTIR spectral analysis strong and broad peak observed at 3384 cm−1 can be attributed to (O-H) functional groups of the bioactive compounds which act as reducing and capping agents for the synthesis of CuO Nps in the plant extract. The SEM images of green synthesized CuO NPs was appeared to be aggregated form and almost spherical in shape. The antimicrobial activity of CuO Nps was evaluated against S.aureus and B.cereus (gram-positive), E. coli (gram-negative) bacteria strains and C.albicans fungal Pathogen. The result indicated that at weight fraction of 50 %, CuO Nps exhibit highest antimicrobial activity against E. coli, S. aureus, C.albicans and B.cereus with zone of inhibition of 26.0 ± 0.10, 25.0 ± 0.15, 18.1 ± 0.32 and 17.0 ± 0.0 mm respectively. Furthermore, for the E. coli bacterial strain, the minimum inhibitory concentration (MIC) of CuO Nps was found to be 1.56 mg/mL; whereas, for S. aureus and C. albicans was found to be 3.12 mg/mL. Therefore, the present study shows that Rosmarinus officinalis extract can be easily used as a reducing, stabilizing, and capping agent for the effective green synthesis of CuO Nps for antimicrobial agents. Thus, it is believed that synthesis of nanoparticles using low cost and eco-friendly green approach enhanced the antimicrobial activity and other a potentially applications in fields of biomedical.

Unravelling High Water Vapor-Induced Inhibitory Effects on Pt/Co3O4 Catalysts toward Benzene Oxidation.

Water vapor inevitably exists in the environment, which causes adverse impacts on many crucial chemical reactions. However, high water vapor of up to 10 vol %─relevant to a broad spectrum of industrial practices-for catalytic implications has been less investigated or neglected. As such, we explored an industry-relevant, humidity-highly sensitive benzene oxidation only in the presence of 10 vol % water vapor using the well-established Pt/Co3O4 catalysts, to bring such an important yet ignored topic to the forefront. Results revealed that Pt/Co3O4 catalysts possessing higher contents of Pt nanoparticles exhibited marked tolerance to water vapor interference. Under an incomplete benzene conversion condition, the input of 10 vol % water vapor indeed impaired the catalytic performance of Pt/Co3O4 catalyst significantly, which, in fact, was caused by the unfavorable formation of carboxylate species covering the catalyst's surface engendering irrecoverable activity loss, instead of the well-accepted water competitive adsorption. While such activity loss can be restored by elevating the reaction to a higher temperature. This study helps us to understand the compromised catalytic activity caused by high humidity, urging the systematic evaluation of well-established catalyst systems in high water vapor-contained conditions and pressing the development of water-tolerant catalysts for real-life application consideration.

4D printing thermo-magneto-responsive PETG-Fe3O4 nanocomposites with enhanced shape memory effects

In this groundbreaking study, Polyethylene Terephthalate Glycol (PETG)-Fe3O4 nanocomposites were developed for 4D printing, incorporating iron oxide (Fe3O4) nanoparticles into PETG matrix. The research contribution lies in its innovative approach to enhancing the shape memory effect (SME) through thermo-magnetic responsiveness, positioning PETG-Fe3O4 as a revolutionary material in smart additive manufacturing. The composites were synthesized using a melt mixing method, followed by 3D printing into specimens for comprehensive evaluation through dynamic mechanical thermal analysis (DMTA), scanning electron microscopy (SEM), and uniaxial tensile tests. The findings revealed that the incorporation of Fe3O4 nanoparticles significantly boosts the composites’ storage modulus and glass transition temperature, indicative of improved stiffness and thermal properties. Notably, the 15 % Fe3O4 composite emerged as the optimal blend, exhibiting the highest tensile strength and a favourable balance between mechanical integrity and flexibility. A key result was the enhanced SME under both thermal and magnetic stimuli, with recovery efficiency and speed escalating with nanoparticle concentration. This advancement underscores the potential of PETG-Fe3O4 nanocomposites in fabricating smart structures capable of environmental adaptability, paving the way for impacts in biomedical, aerospace, and robotic devices. Through this work, a new paradigm in material functionality for 4D printing has been established, demonstrating the viability of magnetic nanoparticle integration for added smart capabilities.

Low-dose zinc oxide nanoparticles trigger the growth and biofilm formation of Pseudomonas aeruginosa: a hormetic response

IntroductionHormesis describes an inverse dose-response relationship, whereby a high dose of a toxic compound is inhibitory, and a low dose is stimulatory. This study explores the hormetic response of low concentrations of zinc oxide nanoparticles (ZnO NPs) toward Pseudomonas aeruginosa.MethodSamples of P. aeruginosa, i.e. the reference strain, ATCC 27,853, together with six strains recovered from patients with cystic fibrosis, were exposed to ten decreasing ZnO NPs doses (0.78–400 µg/mL). The ZnO NPs were manufactured from Peganum harmala using a chemical green synthesis approach, and their properties were verified utilizing X-ray diffraction and scanning electron microscopy. A microtiter plate technique was employed to investigate the impact of ZnO NPs on the growth, biofilm formation and metabolic activity of P. aeruginosa. Real-time polymerase chain reactions were performed to determine the effect of ZnO NPs on the expression of seven biofilm-encoding genes.ResultThe ZnO NPs demonstrated concentration-dependent bactericidal and antibiofilm efficiency at concentrations of 100–400 µg/mL. However, growth was significantly stimulated at ZnO NPs concentration of 25 µg/mL (ATCC 27853, Pa 3 and Pa 4) and at 12.5 µg/mL and 6.25 µg/mL (ATCC 27853, Pa 2, Pa 4 and Pa 5). No significant positive growth was detected at dilutions < 6.25 µg/mL. similarly, biofilm formation was stimulated at concentration of 12.5 µg/mL (ATCC 27853 and Pa 1) and at 6.25 µg/mL (Pa 4). At concentration of 12.5 µg/mL, ZnO NPs upregulated the expression of LasB ( ATCC 27853, Pa 1 and Pa 4) and LasR and LasI (ATCC 27853 and Pa 1) as well as RhII expression (ATCC 27853, Pa 2 and Pa 4).ConclusionWhen exposed to low ZnO NPs concentrations, P. aeruginosa behaves in a hormetic manner, undergoing positive growth and biofilm formation. These results highlight the importance of understanding the response of P. aeruginosa following exposure to low ZnO NPs concentrations.

3D-MHD mixed convection in a darcy-forchheimer maxwell fluid: Thermo diffusion, diffusion-thermo effects, and activation energy influence

In this article, the three-dimensional upper-convected Darcy-Forchheimer Maxwell (UCM) nanofluid flow over a stretching surface is analyzed to investigate the effects of activation energy, thermodiffusion, diffusion thermo, and magnetohydrodynamics (MHD) on heat and mass transfer. The energy equation incorporates a nonlinear radiative heat flux. Using similarity transformation, the nonlinear partial differential equations are reduced to ordinary differential equations, which are then solved using the well-known shooting technique via the fourth-order Runge-Kutta integration method. To validate our results, we also employ MATLAB's built-in function bvp4c. The impact of various parameters, such as activation energy, diffusion thermo, thermodiffusion, Brownian motion parameter, Prandtl number, thermophoresis parameter, and magnetic parameter, on velocity, temperature, and concentration is discussed both graphically and numerically. It is observed that the flow velocity decreases with an increasing magnetic field parameter. Additionally, higher values of the activation energy parameter reduce the nanoparticle concentration profile. The temperature and concentration exhibit opposite behaviors when thermodiffusion and diffusion thermo effects are enhanced.

Correction for Partial Volume Averaging in the Quantification of Radiopaque Nanomaterial-Embedded Resorbable Polymers.

Resorbable inferior vena cava (IVC) filters require embedded contrast for image-guided placement and integrity monitoring. We calculated correction factors to account for partial volume averaging of thin nanoparticle (NP)-embedded materials, accounting for object and slice thicknesses, background signal, and nanoparticle concentration. We used phantoms containing polycaprolactone disks embedded with bismuth (Bi) or ytterbium (Yb): 0.4- to 1.2-mm-thick disks of 20 mg/mL NPs (thickness phantom), 0.4-mm-thick disks of 0-20 mg/mL NPs in 2 mg/mL iodine (concentration phantom), and 20 mg/mL NPs in 0.4-mm-thick disks in 0-10 mg/mL iodine (background phantom). Phantoms were scanned on a dual-source CT with 80, 90, 100, and 150 kVp with tin filtration and reconstructed at 1.0- to 1.5-mm slice thickness with a 0.1-mm interval. Following scanning, disks were processed for inductively coupled plasma optical emission spectrometry (ICP-OES) to determine NP concentration. Mean and maximum CT numbers (HU) of all disks were measured over a 0.5-cm2 area for each kVp. HU was converted to concentration using previously measured calibrations. Concentration measurements were corrected for partial volume averaging by subtracting residual slice background and extrapolating disk thickness to both nominal and measured slice sensitivity profiles (SSP). Slice thickness to agreement (STTA) was calculated by replacing the CT-derived concentrations with ICP-OES measurements and solving for thickness. Slice thickness correction factors improved agreement with ICP-OES for all measured data. Yb corrections resulted in lower STTA than Bi corrections in the concentration phantom (1.01 vs 1.31 STTA/SSP, where 1.0 is perfect agreement), phantoms with varying thickness (1.30 vs 1.87 STTA/SSP), and similar ratio in phantoms with varying background iodine concentration (1.34 vs 1.35 STTA/SSP). All measured concentrations correlated strongly with ICP-OES and all corrections for partial volume averaging increased agreement with ICP-OES concentration, demonstrating potential for monitoring the integrity of thin IVC resorbable filters with CT.&#xD.

Vat photopolymerization of silica reinforced styrene-butadiene rubber elastomeric nanocomposites

Compared to their unfilled counterparts, elastomeric nanocomposites offer tailorable combinations of properties, including improved mechanical properties, increased durability, and enhanced thermal and electrical conductivity. However, the high viscosity caused by the presence of both the high molecular weight elastomer and the inclusion of fillers complicates additive manufacturing (AM) of elastomeric nanocomposites. This is especially challenging in vat photopolymerization (VP) AM, which requires resins that possess low viscosity (< 10 Pa·s) and exhibit sufficient storage modulus (∼ 104 Pa) when photocured. To address this process limitation, the authors have previously demonstrated decoupling the relationship between viscosity and molecular weight via VP of a photocurable composite latex resin. In this approach, a photocurable matrix is photocured as a scaffold around the latex particles, which provides sufficient modulus for the printed "green" part. Following a dehydration post-processing step, the latex particles coalesce to provide the final elastomeric mechanical properties without compromising feature resolution.In this work, the authors explore the effects of the addition of silica nanoparticles (10, 15, and 20 wt.%) on (i) the printability of photocurable styrene-butadiene rubber (SBR) latex resin and (ii) the mechanical properties of the resultant printed composites. The printable photocurable silica-SBR colloidal resin is realized by balancing the viscosity of the resin, the modulus of the cured green body, the silica nanoparticles content for reinforcement, and the high SBR content for elastomeric behavior. Specifically, the photocurable colloidal resin's viscosity is controlled by formulation design, while high silica nanoparticle content in the final part is achieved through evaporation of unreactive diluent. Characterization of the printed SBR nanocomposites with 20 wt.% silica reinforcement elucidated significant enhancements in the tensile strength (53 % increase), Young's modulus (671 % increase), and Shore A hardness (108 % increase) compared to printed SBR without filler reinforcement. To the authors' knowledge, this is the first report of 3D printing rubber nanocomposite using VP.

Advances in nanofluids for tubular heat exchangers: Thermal performance, environmental effects, economics and outlook

Heat transfer deterioration in thermal systems significantly limits the efficiency and practicality of these systems. This review explores state-of-the-art studies on the use of nanofluids (NFs) in various tubular heat exchangers (HEXs), addressing their influence on overcoming the limitations. It discusses the fundamentals of HEXs and NFs, including design criteria, heat transfer mechanisms and thermal transport properties. This work compiles effective thermal conductivity and viscosity correlations under diverse conditions and evaluates NF performance in reactor, flat and helical coiled tube, twisted tube, U-tube and finned tube-based HEXs. Results revealed substantial improvements in system efficiency, with SiC–MWCNT/water NFs achieving 99.9% absorbance in solar collectors and Ag–rGO/water and Ag–ZnO/silicon oil NFs enhancing efficiency by 210% and 240%, respectively. Water–alumina NFs increased convective heat transfer rates and friction factors in flat tube HEXs by 123.6% and 210%, respectively. Helical coil exchangers exhibited a pressure drop of 47.35% with MWCNT/water NFs and a 69.62% rise in heat transfer coefficient with polyaniline–water NFs. This review suggests that optimising HEX efficiency depends on the strategic use of NFs and finned-tube designs. It also highlights the significance of selecting suitable source materials for NFs, the corresponding health risks, disposal and waste management. Economic viability depends on using optimal flow parameters, including temperature, concentration of nanoparticles, system compactness and installation and running costs. Finally, this review concludes with insights into existing challenges and prospects in thermohydraulic, environmental and economic aspects, pointing to future developments in engineered fluids and their commercial applications.

Mechanical properties of polymer composite films with ZnO nanoparticles synthesized in low-temperature plasma under ultrasonic cavitation

Abstract In this study, polymer nanocomposite materials consisting of the copolymer of ethylene and vinyl acetate as a matrix and nanoparticles of zinc oxide as a filler have been obtained and examined by physicochemical and mechanical methods. Zinc oxide nanoparticles used in this study were fabricated using the plasma discharge under the effect of intensive ultrasonic cavitation. To ensure that resulting nanocomposites will acquire homogeneous distribution of filler nanoparticles, solution technology was utilized followed by the melt compounding technique, and also nanoparticles treated and non-treated with ultrasound were applied. The fabricated samples of nanocomposite material films were examined by X-ray phase analysis, then X-ray fluorescence analysis as well as scanning electron microscopy. The differences between the samples were demonstrated: when the nanoparticles without ultrasonic treatment were used, the particles were found to be more strongly aggregated within the bulk of the composite material and the average size of particles was visually larger in comparison to the sample filled with nanoparticles subjected to ultrasonic action. Finally, studies of the tensile strength and relative deformation of the samples were carried out. From the results of mechanical tests, it can be seen that, according to both studied parameters, there is an optimal concentration of ZnO nanoparticles. For tensile strength, the highest result was obtained at a concentration of nanoparticles of 3%, and for the relative elongation to rupture of the sample, the highest value was achieved at a concentration of nanoparticles of 2%.

Flexural properties of additive manufactured resin designated for interim fixed dental prosthesis: Effect of nanoparticles, build direction, and artificial aging

ObjectiveThis study investigates the flexural strength and elastic modulus of three-dimension (3D) printed interim resin (ASIGA) incorporating zirconium dioxide (nano-ZrO2) and silicon dioxide (nano-SiO2) nanoparticles (NPs) with different build direction and after artificial aging. MethodsThree hundred 3D-printed specimens were used for testing. Groups were modified with nano-ZrO2 or nano-SiO2 at concentrations of 0.5 wt% or 1 wt% and an unmodified control group remained unmodified (n = 10). The bar-shaped specimens (25 x 2 x 2 mm) were printed at 0, 45, and 90 degree orientations. Flexural properties were assessed using a universal testing machine. The study employed various analyses to assess material properties and bonding. ResultsThe flexural strength was significantly improved (P<0.001) by the inclusion of nano-ZrO2 or nano-SiO2, with a maximum value of 61.8 ± 4.3 MPa with 1 wt% nano-ZrO2 at 45° build direction. The highest elastic modulus value observed was 998.2 ± 91.2 MPa with 0.5 wt% nano-SiO2 at 90° build direction. Build direction, NP type, and NP concentration all had a statistically significant combined effect on flexural strength and elastic modulus (P=0.003*, P=0.045), respectively. ConclusionIncorporation of nano-SiO2 and nano-ZrO2 increased the flexural properties of the interim resin used in 3D printing. Following artificial aging, all the flexural property values in the modified groups showedminimal reduction regardless of the nanoparticle concentration, while the unmodified control group showed a significant reduction. Before and after artificial aging, samples at a 0 degree build direction had a considerably higher flexural strength, although the highest elastic modulus values were found in the 90 degree group. The findings underscore the potential of nanocomposites in strengthening interim dental restorations, offering promising advancements for clinical practice.

Experimental and numerical study on ferrohydrodynamic and magneto-convection of Fe3O4/water ferrofluid in a sudden expansion tube with dimpled fins

BackgroundThis study experimentally and numerically addresses magnetohydrodynamic forced convection including dimpled fins, Fe3O4/water ferrofluid, and DC magnetic field. In this research, focusing on the thermo-hydraulic performance improvement of a sudden expansion tube. It has been used different inlet diameters, dimple sizes, ferro nanoparticle concentrations, and magnetic field strengths to examine the heat transfer and fluid dynamics characteristics of the system. MethodsThe study consists of two parts, i) experimental and ii) numerical. Steady-state, incompressible, Newtonian flow were considered but chemical reaction, viscous dissipation, buoyancy, and radiative heat transfer were neglected in this study. On the other hand, numerical solutions were carried out for single-phase method. This study was first compared with the studies in the literature on the flow in a sudden expansion tube without dimpled fins and the error rate was found to be less than 10 %. In the analysis, dimpled fins with d=3, 5, and 7 mm at each P=15 mm (P/d=5.0, 3.0, and 2.14) have been used. As working fluid, Fe3O4/water ferrofluid with volume concentration of φ=1.0 % and 2.0 % have been analyzed. Additionally, DC magnetic fields, which strength of Ha=0.1, 0.3, 0.5, 1.1, 3.2, and 5.3 (B =0.01, 0.03, 0.05, 0.1, 0.3, and 0.5T), have been applied on the sudden expansion tube surface as external force. Significant findingsDimpled fins enhance the heat transfer by disrupting the boundary layer and forming secondary flows, while the ferrofluid increases the thermal conductivity and viscosity of the base fluid. Based on these explanations, dimpled fins increased the convective heat transfer rate at the rate of 96.0 % compared with smooth tube. In addition, Fe3O4/water ferrofluid with φ=2.0 % performed the highest performance and performance evaluation criteria increased by 8.5 %. The magnetic field also contributes to the heat transfer enhancement by inducing Lorentz force and mixing the flow. Excessive increasing of magnetic field strength adversely affected the system performance, and the highest performance evaluation criterion is acquired at Ha=3.2 by increasing 3.9 %. Compared with smooth tube, compound effect of dimpled fins, Fe3O4/water ferrofluid, and magnetic field improved the average Nusselt number and performance evaluation criterion at the rate of 279.8 % and 207.9 %, respectively.

Synthesis of Zinc Nanoparticles in Hibiscus sabdariffa Plant Extract and Investigation of Its Antimicrobial Properties

Background: The use of nanotechnology in various biomedical and pharmaceutical fields is expanding rapidly. Objectives: The aim of this study was to synthesize zinc nanoparticles using Hibiscus sabdariffa plant extract and investigate their antimicrobial properties. Methods: In this experimental study, the aqueous extract of sour tea was mixed with a 0.1 M zinc sulfate solution at a 1:1 ratio and allowed to react for 15 minutes at room temperature to produce nanoparticles. The synthesis of zinc oxide nanoparticles was confirmed using spectrophotometric methods, measuring the average diameter of nanoparticles, X-ray diffraction, and scanning electron microscopy (SEM). The minimum inhibitory concentration (MIC) of the zinc oxide nanoparticles was then measured against standard strains. Results: The results showed that the largest inhibition zone diameter was observed at a concentration of 1024 μg/mL against Listeria monocytogenes, while the smallest inhibition zone was observed against Aeromonas hydrophila. At a concentration of 512 μg/mL, an inhibition zone of 10 mm was developed against two strains: Vibrio cholerae and Escherichia coli. Conclusions: Based on the results of this study, zinc oxide nanoparticles, along with the sour tea aqueous extract and zinc sulfate, exhibited antibacterial properties. However, the most pronounced antimicrobial effects were observed with the zinc oxide nanoparticles.

Enhanced anticancer effect of lysozyme-functionalized metformin-loaded shellac nanoparticles on a 3D cell model: role of the nanoparticle and payload concentrations.

Here we used a 3D human hepatic tumour cell culture model to assess the in vitro efficacy of "active" metformin-loaded nanoparticles (NPs) as anticancer therapeutics. The metformin nanocarrier design was repurposed from previous studies targeting bacterial and fungal biofilms with antimicrobials loaded in protease-coated nanoparticles. These active nanocarriers were constructed with shellac cores loaded with metformin as the anticancer agent and featured a surface coating of the cationic protease lysozyme. The lysozyme's role as a nanocarrier surface coating is to partially digest the extracellular matrix (ECM) of the 3D tumour cell culture which increases its porosity and the nanocarrier penetration. Hep-G2 hepatic 3D clusteroids were formed using a water-in-water (w/w) Pickering emulsion based on an aqueous two-phase system (ATPS). Our specific metformin nano-formulation, comprising 0.25 wt% lysozyme-coated, 0.4 wt% metformin-loaded, 0.2 wt% shellac NPs sterically stabilized with 0.25 wt% Poloxamer 407, demonstrated significantly enhanced anticancer efficiency on 3D hepatic tumour cell clusteroids. We examined the role of the lysozyme surface functionality of the metformin nanocarriers in their ability to kill both 2D and 3D hepatic tumour cell cultures. The anticancer efficiency at high metformin payloads was compared with that at a high concentration of nanocarriers with a lower metformin payload. It was discovered that the high metformin payload NPs were more efficient than the lower metformin payload NPs with a higher nanocarrier concentration. This study introduces a reliable in vitro model for potential targeting of solid tumours with smart nano-therapeutics, presenting a viable alternative to animal testing for evaluating anticancer nanotechnologies.

Flexible Scaffold Modulation of Spatial Structure and Function of Hierarchically Porous Nanoparticle@ZIF-8 Composites to Enhance Field Deployable Disease Diagnostics.

Catalytic nanoparticle@metal-organic framework (MOF) composites have attracted significant interest in point-of-care testing (POCT) owing to their prominent catalytic activity. However, the trade-off between high loading efficiency and high catalytic activity remains challenging because high concentrations of nanoparticles tend to cause the misjoining and collapse of the MOFs. Herein, a facile strategy is reported to encapsulate high concentrations of platinum (Pt) nanoparticles into zeolitic imidazolate framework-8 (ZIF-8) using polydopamine (PDA) as a support for Pt@ZIF-8 and as a flexible scaffold for further immobilization of Pt nanoparticles. The resulting composite (Pt@ZIF-8@PDA@Pt) exhibits ultrahigh Pt nanoparticle loading efficiency, exceptional catalytic activity, stability, and a bright colorimetric signal. Following integration with lateral flow immunoassay (LFIA), the detection limits for pre- and post-catalysis detection of B-type natriuretic peptide (NT-proBNP) are 0.18 and 0.015ng mL-1, respectively, representing a 6-fold and 70-fold improvement compared to gold nanoparticle-based LFIA. Moreover, Pt@ZIF-8@PDA@Pt-based LFIA achieves 100% diagnostic sensitivity for NT-proBNP in a cohort of 184 clinical samples.

DLS homemade setup: reviewing first and second-order coherence and autocorrelation concepts of a light source in the context of nanoparticle sizes synthesized by PLAL

The size of the nanoparticles (NP) is one of the most important and essential characteristics to know the properties of the synthesized nanostructures. The most common characterization procedures are related to Scanning Electronic Microscopy (SEM), Transmission Electronic Microscopy (TEM), and Atomic Force Microscopy (AFM). Unfortunately, from a practical point of view, they represent a time-consuming procedure and require expensive equipment, which limits its application to specialized research groups. Significant attention has been paid to Dynamic Light Scattering (DLS) as a simple, fast, and reproducible method for sizing nanoparticles. However, inadequate representation of the fundamental principles of DLS and data interpretation represents two of the most important challenges related to this technique. In this work we try to provide the fundamental principles of the DLS technique, the fundamental mathematical treatment of data obtained during the optical scattering studies and provide the MATLAB code to configure non-commercial DLS equipment. Additionally, analyzes of nanoparticles obtained by pulsed laser ablation of Ag, Au, Si and W and commercial Au nanoparticles were carried out. The particle size results are compared with SEM images to calculate the percentage error of the DLS measurements. The results show an error of 5%, 3.8%, 2.1% for the Ag, Au and Si nanoparticles respectively, which proves to be an excellent approximation to the real values of nanoparticle diameter. Meanwhile, the error in size for W nanoparticles by the same technique and commercial Au nanoparticle is 29% and 12%, which shows the effect of the hydrodynamic diameter of the nanoparticles. This work ends with the analysis of the concentration of nanoparticles and its importance in reliable results of DLS measurements.