Nanoparticle Mass Research Articles

COMPUTATIONAL MODELLING OF HEAT AND MASS TRANSFER OPTIMIZATION IN COPPER WATER NANOFLUID FLOW WITH NANOPARTICLE IONIZATION

An exploration is carried out to model the heat and mass transfer optimization of Cu-water nanofluid in a natural convective flow over a vertical plane wall with Cu-nanoparticle ionization. Nanoparticle ionization mechanism has been included in the modelling of nanofluid flow. Using the similarity transformation method, the basic two-dimensional momentum, energy, and nanoparticle concentration equations have been transferred to a set of locally similar equations and solved numerically using MATLAB bvp4c function. The impacts of the nanoparticle ionization on the nanofluid flow parameters, skin- friction, heat transfer and nanoparticle mass transfer coefficients are determined and shown graphically. The major outcome of the present study reveals that an increment in the ionization parameter elevates the skin-friction, heat and mass transfer rate from the wall to nanofluid. It is concluded that Cu-nanoparticle ionization contributes towards the augmentation of heat and mass transfer capabilities of Cu-water nanofluid.

Impact of Experimental Conditions on Extracellular Vesicles' Proteome: A Comparative Study.

Extracellular vesicle (EV) research is a rapidly developing field, mainly due to the key role of EVs in intercellular communication and pathophysiological processes. However, the heterogeneity of EVs challenges their exploration and the establishment of gold-standard methods. Here, we aimed to reveal the influence of technical changes on EV biology and the reliability of experimental data. We used B16F1 melanoma cells as a model and applied nanoparticle tracking analysis, mass spectrometry (LC-MS/MS) and pathway enrichment analysis to analyze the quantity, size distribution, proteome and function of their small EVs (sEVs) produced in sEV-depleted fetal bovine serum (FBS)-containing medium or serum-free medium. Additionally, we investigated the effects of minor technical variances on the quality of sEV preparations. We found that storage of the isolates at -80 °C has no adverse effect on LC-MS/MS analysis, and an additional washing step after differential ultracentrifugation has a minor influence on the sEV proteome. In contrast, FBS starvation affects the production and proteome of sEVs; moreover, these vesicles may have a greater impact on protein metabolism, but a smaller impact on cell adhesion and membrane raft assembly, than the control sEVs. As we demonstrated that FBS starvation has a strong influence on sEV biology, applying serum-free conditions might be considered in in vitro sEV studies.

Proposing and optimization of a parabolic trough solar collector integrated with a photovoltaic module layer

Parabolic trough collector (PTC) is a type of solar system that generates thermal energy by concentrating solar radiation on the surface of a circular receiver tube. However, the overall output of this solar system can be significantly enhanced by the integration of this system with Photovoltaic (PV) modules which is proposed and comprehensively investigated in this research using 3D validated numerical simulation. In the first step of this study, all operating parameters of the new PTC/PV system (i.e. thickness of the air gap, the glass cover thickness, copper nanoparticles mass fraction, and PV cell efficiency) are optimized by employing the Taguchi method. Afterward, it is attempted to enhance further the efficiency of the optimized PTC/PV system by rotating the receiver tube of the system and also installing metal foam inside the fluid channel of the receiver tube. According to the Taguchi method, the maximum overall performance of the PTC/PV system is 71.1%, when the glass cover thickness, air gap thickness, PV cell efficiency, and nanoparticles mass fraction are 2 mm, 10 mm, 21%, and 6%, respectively. Additionally, the numerical simulations show that rotating the receiver tube of the optimized PTC/PV system can augment the overall efficiency of the system from 71.1% to 82.5%, which is due to the improvement in heat transfer rate from the tube to the operating fluid. However, by rotating the receiver tube, the electrical efficiency of the PV cells reduces from 16.0% to 14.9%. Additionally, installing metal foam inside the receiver tube can boost the electrical and overall efficiency of the fixed PTC/PV system by approximately 2% and 13.9%, respectively. It is worth mentioning that adding foam to the rotating receiver tube declines the thermal efficiency of the system by around 0.5%.

MIL-68 (In) and ZIF-8 assisted construction of n-n heterostructure for the effective sensing of trace-level ozone

The crucial challenge to exploit effective ozone (O3) gas sensors lies in developing novel functional sensing materials to meet the requirement of trace-level detection threshold (50 ppb). Metal oxide semiconductors (MOSs) with controllable heterogenous composites as high-performance sensing layers are expected to break through this bottleneck. This work proposes the hybridization of MIL-68 (In) and ZIF-8, which are employed as dual metal organic frameworks (MOFs) sacrificial templates to design n-n heterostructures. The derived In2O3 backbone showed a hexagonal prismatic structure with a large aspect ratio. The robust architecture enabled the uniform decoration of mass of ZnO nanoparticles (NPs) on the surfaces without the damage of high porosity for the gas diffusion. Consequently, the optimal sensor with appropriate ZnO NPs loading amount exhibited trace O3 detection ability as low as 15 ppb, which was attributed to the smart design of n-n heterostructure, rich active sites and improved oxygen-adsorbing capacity. Thus, this work inspires a new way to utilize the versatile dual MOFs template for constructing heterogenous composites as O3 sensing materials.

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation (NIPS) process was used to fabricate a series of sulfonated polyethersulfone (SPES) membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration (UF) process. SBA-15 was modified with 3-methacrylate-propyltrimethoxysilane (MPS) to form SBA-15-g-MPS. It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt. The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane. The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability, hydrophilicity, and antifouling properties. The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane. For the membrane containing 5% (mass) of SBA-15-g-PSPA (MSSPA5), the pure water flux was increased dramatically to 402.15 L∙m –2 ∙h –1 , which is ∼ 1.5 times that of MSSPA0 (268.0 L∙m –2 ∙h –1 ). The high flux rate was achieved with 3% (mass) of SBA-15 nanoparticles with retained high rejection ratio 98% for natural organic matter. The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.

Ce1-xZrxO2 nanoparticles in bacterial cellulose, bio-based composites with self-regenerating antioxidant capabilities.

Bacterial cellulose (BC) is an emerging biopolymer with ever-widening uses in the biomedical field due to its purity, mechanical stability, conformability, moisture control, and biocompatibility. In the wet form, its highly porous nanofibrillar structure and abundant surface hydroxyl groups enable the functionalisation of BC with inorganic nanoparticles (NPs), granting the material additional purposive capabilities. As oxidative stress caused by reactive oxygen species (ROS) negatively affects various cellular structures, the functionalisation of BC with CeO2 NPs, known antioxidants, is pursued in this work to achieve composites capable of minimising inflammation and tissue damage. We report on low-temperature in situ syntheses of CeO2 NPs in BC enabling the formation of BC-CeO2 composites that exhibit self-regenerating antioxidant properties, as verified by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays and studies of the evolution in the CeO2 absorption edge (indicative of the Ce3+ and Ce4+ fractions). X-Ray photoelectron spectroscopy (XPS) further reveals that incorporation of zirconium into the CeO2 lattice leads to a four-fold increase in the Ce3+: Ce4+ ratio, thereby enhancing the composite antioxidant performance as exemplified by BC-Ce0.6Zr0.4O2 recording the highest %DPPH scavenging per unit mass of NPs among the BC-Ce1-xZrxO2 studied systems.

Theranostic inorganic-organic hybrid nanoparticles with a cocktail of chemotherapeutic and cytostatic drugs.

Theranostic inorganic-organic hybrid nanoparticles (IOH-NPs) with a cocktail of chemotherapeutic and cytostatic drugs and a composition Gd23+[(PMX)0.5(EMP)0.5]32-, [Gd(OH)]2+[(PMX)0.74(AlPCS4)0.13]2-, or [Gd(OH)]2+[(PMX)0.70(TPPS4)0.15]2- (PMX: pemetrexed, EMP: estramustine phosphate, AlPCS4: aluminum(III) chlorido phthalocyanine tetrasulfonate, TPPS4: tetraphenylporphine sulfonate) are presented for the first time. These IOH-NPs are prepared in water (40-60 nm in size) and have a non-complex composition with outstanding drug loading (71-82% of total nanoparticle mass) of at least two chemotherapeutic or a mixture of cytostatic and photosensitizing agents. All IOH-NPs show red to deep-red emission (650-800 nm) to enable optical imaging. The superior performance of the IOH-NPs with a chemotherapeutic/cytostatic cocktail is validated based on cell-viability assays and angiogenesis studies with human umbilical vein endothelial cells (HUVEC). The synergistic anti-cancer effect of the IOH-NPs with a chemotherapeutic cocktail is shown in a murine breast-cancer cell line (pH8N8) and a human pancreatic cancer cell line (AsPC1), whereas the synergistic cytotoxic and phototoxic efficacy is verified in response to illumination of HeLa-GFP cancer cells, MTT assays with human colon cancer cells (HCT116), and normal human dermal fibroblasts (NHDF). HepG2 spheroids as 3D cell cultures prove the effective uptake of the IOH-NPs with high uniform distribution and the release of the chemotherapeutic drugs with the strong synergistic effect of the cocktail of drugs.

Impact of magnetized non-linear radiative flow on 3D chemically reactive sutterby nanofluid capturing heat sink/source aspects

A recent advancement in fluid dynamics is the consideration of nanofluids which has an extraordinary thermal conductivity characteristics and upsurge heat transfer in fluids. This paper examines the heat and mass transfer properties of a steady 3D movement of a sutterby nanomaterial on a bidirectional stretching plane. Nanoparticle mass flow and convective boundary conditions are deliberated. In addition, the effect of heat generation/absorption and non-linear thermal radiation is explored. Moreover, the latest proposed model of the nanofluid has been pondered which involves controlling the nanoparticle volume element at the wall submissively relatively than dynamically. We introduced a similarity transformation to change the equations of boundary layer to a self-similar system after that processed analytically with the help of the bvp4c scheme. The outcomes of several control parameters on heat and mass transfer properties are shown among graphs then scrutinized. The systematic outputs of the Nusselt number are premeditated via tables. We observed that by increasing the estimates of the Lewis number (Le) indicates a reduction in the concentration field as well as the thickness of the equivalent boundary layer. Similarly, it is seen that the concentration field decreases rapidly according to the Brownian motion parameter as compared to the Lewis number (Le).

Development and Laboratory Scale Characterization of a New Hybrid Nano‐enhanced Phase Change Material for Solar Thermal Energy Storage

AbstractThe latent heat thermal energy storage (LHTES) systems using organic phase change materials (PCMs) offer significant advantages, however, they suffer with low thermal conductivity and this limitation restricts their uses in many real applications. This weakness of them has attracted the attention of worldwide researchers. In the present work, a novel hybrid organic phase change material (HOPCMs) using two‐step method is prepared by the addition of copper oxide and titanium oxide nanoparticles in different mass fraction ratio for elevating the thermal conductivity of myristic acid (MA) as base PCM. The findings of this experimental work show that with the addition of 75 % CuO and 25 % TiO2 of total 1 % of combined nanoparticles mass fraction, the thermal conductivity of pure PCM enhances by an amount of 13.16 %. The thermo‐physical properties were obtained using differential scanning calorimetry and they show that by the addition of hybrid nanoparticles, PCM does not loses its latent heat by more than 2 %. The chemical and thermal properties were tested by adopting Fourier transform and infrared spectrometer (FT‐IR), X‐ray diffraction (XRD) technique, and thermogravimetric (TGA) analyzer. The reliability and stability of the HOPCMs were checked by conducting accelerated thermal melt/freeze cycle test for 1000 cycles. The HOPCMs so obtained, reveal the good thermal and chemical properties, and ensure a long‐term performance for medium temperature based LHTES systems.

Flow and Heat Transfer Analysis MHD Nanofluid due to Convective Stretching Sheet

Objectives: The study of flow and heat transfer on a permeable stretching sheet of Magnetohydrodynamic nanofluid under the influence of convective boundary condition is presented in this article. Mathematical modeling for the law of conservation of mass, momentum, heat and concentration of nanoparticles is executed. Methods: Governing nonlinear partial differential equations are reduced into nonlinear ordinary differential equations and then shooting method with fourth order Adams-Moulton Method is employed for its solution. Findings: The effects of magnetic parameter (0  M  2), Thermophoresis parameter (0:1  Nt  0:7) Lewis number (1  Le  4), Suction parameter (0  fw  3), Biot number(0:1  Bi  0:7) and Viscous dissipation(0  Ec  4) on axial velocity, temperature and concentration profiles are shown graphically. Numerical results were compared with another numerical approach and an excellent agreement was observed. The solutions under the impacts of different physical governing parameters are illustrated by means of graphs and tables. Effects of viscous dissipation is also discussed. Novelty: Despite the enormous importance and repeated application of nanofluids in industry and science, no attempt has been made to investigate the viscous dissipation effect on heat transfer with a permeable linear stretch sheet. Keywords: MHD; Nanofluid; Stretching Sheet; Viscous dissipation; Shooting technique; Adams-Moulton Method

Uptake of Cationic PAMAM-PLGA Nanoparticles by the Nasal Mucosa

Nanoparticles provide promising advantages in advanced delivery systems for enhanced drug delivery and targeting. The use of a biodegradable polymer such as PLGA (poly lactic-co-glycolic acid) promotes improved nanoparticle safety and, to some extent, provides the ability to modify nanoparticle surface properties. This study compared the effect of altering the surface charge on the translocation of PLGA nanoparticles across excised nasal mucosal tissues. Nanoparticles (average diameter of 60–100 nm) loaded with Nile Red (lipophilic fluorescent dye) were fabricated using a nanoprecipitation method. The effects of nanoparticle surface charge were investigated by comparing the transfer of untreated nanoparticles (negatively charged) and positively charged PLGA nanoparticles, which were modified using PAMAM dendrimer (polyamidoamine, 5th generation). All nanoparticles were able to be transferred in measurable quantities into both nasal respiratory and olfactory mucosae within 30 min. The total nanoparticle uptake was less than 5% of the nanoparticle mass exposed to the tissue surface. The cationic nanoparticles showed a significantly lower transfer into the mucosal tissues where the amount of nanoparticles transferred was 1.8–4-fold lower compared to the untreated negatively charged nanoparticles. The modification of the nanoparticle surface charge can alter the nanoparticle interaction with the nasal epithelial surface, which can result in decreasing the nanoparticle transfer into the nasal mucosa.

Experimental Analysis of the Thermal Performance Enhancement of a Vertical Helical Coil Heat Exchanger Using Copper Oxide-Graphene (80-20%) Hybrid Nanofluid

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.

Nano-bio-film flow of Williamson fluid due to a non-linearly extending/contracting surface with non-uniform physical properties

The major goal of this paper is to investigate a conceptual framework for nano-biofilm of Williamson fluid over an enlarging/compressing sheet. The impact of activation energy, magnetic field, and bioconvection are studied. Here, the analysis is carried out with varying physical properties such as viscosity, microorganism diffusivity, and thermal conductivity to be depending upon the concentration of nano-particles. The fluid's changing transport properties, dynamic viscosity, heat conductivity, and nano-particle mass diffusivity are calculated. This work's outcomes have applications in dense thermal transit devices such as heat exchangers, nuclear plants, and electronics. Non-linear systems of partial differential equations are transformed into non-linear fundamental differential equations via a similarity transformation. The shooting approach and RK-4 techniques are used to generate observations. The visual depictions of the impacts of various fluid transport characteristics and distinguishing factors on patterns of velocity, temperature, the concentration of nanoparticles, and motile density. Variable transit parameters , , and enhance dispersions of velocity, temperature, concentration and motile density. As the power law index m goes up, the fluid velocity improves, while the heat, concentration and motile intensity profiles decline. This work is useful in devices of dense thermal transportation such as nuclear plants, electronics, and heat exchangers.

O2 Oxidation and Sublimation Kinetics of Single Silicon Nanoparticles at 1200–2050 K: Variation of Reaction Rates, Evolution of Structural and Optical Properties, and the Active-to-Passive Transition

Sublimation and O2 etching kinetics for a series of individual silicon (Si) nanoparticles (NPs) were studied for NP temperatures (TNP) from 1200 to 2050 K using a single NP mass spectrometry technique. Sublimation was significant for TNP > 1700 K, with rates reasonably well fit to Arrhenius kinetics but evolving, particularly during initial heating. O2 etching efficiencies varied from NP-to-NP and with changing TNP, but they also evolved dramatically over time. For TNP ≤ 1500 K, NPs were observed to passivate after losing 30–50% of the initial NP mass. At higher TNP, etching efficiency decreased over time but never passivated. Interestingly, bulk Si passivation has not been observed for the range of TNP and O2 pressures used here, and a model was developed to test the effects of several NP-specific mechanistic parameters on both the initial and time-dependent etching behavior. The optical properties of the hot NPs were also found to evolve as the NPs etched, particularly during the initial fast mass loss, and correlations between emission intensities and etching kinetics were examined.

Thermophysical Properties of Vegetable Oil-Based Hybrid Nanofluids Containing Al2O3-TiO2 Nanoparticles as Insulation Oil for Power Transformers.

The massive demand in the electrical power sector has resulted in a large demand for reliable, cost efficient, and environmentally friendly insulation oil to reduce the dependency on mineral oil. The hybridization of nanoparticles in vegetable oil is a novel method to enhance the thermal properties of vegetable oil. This study focuses on the experimental investigation of the thermophysical properties of coconut oil, soybean oil, and palm oil-based hybrid nanofluids suspended with Al2O3-TiO2 nanoparticles at a mass concentration of 0.2, 0.4, and 0.6%. The ratio between Al2O3 and TiO2 nanoparticles was maintained constant at 50:50. The main purpose of the study is to evaluate the thermal conductivity, dynamic viscosity, and density of different vegetable base oils suspended with Al2O3-TiO2 in the temperature range of 30 to 60 °C. The influence of temperature on the augmentation of thermophysical properties for different vegetable oil-based hybrid nanofluids is investigated experimentally. The experimental results for thermal conductivity for the three types of base fluids show that the effect of nanoparticle mass concentration in thermal conductivity enhancement is less significant for temperatures more than 50 °C. The palm oil with a 0.6% Al2O3-TiO2 nanoparticle concentration exhibited the highest thermal conductivity with a 27.5% thermal conductivity enhancement relative to the base oil. The effect of nanofluid temperature on density and viscosity augmentation is more distinct compared with the impact of Al2O3-TiO2 nanoparticles concentrations. Among all three types of hybrid nanofluids, palm oil based nanofluids were found to have superior thermophysical properties compared with coconut oil and soybean oil, with the highest thermal conductivity of 0.628 W/m·k and lowest viscosity of 17.772 mPa·s.

Electrochemical Detection of Nitrite Ions Using PEDOT Based Films

Poly (3,4-ethylenedioxythiophene) (PEDOT) is an important conducting polymer that is widely studied for applications in photovoltaic devices, thermoelectric materials, batteries, capacitors and sensors [1]. In the field of sensors, PEDOT and PEDOT composites synthesized by chemical and electrochemical methods have been used for the detection of organic and inorganic analytes [2]. In particular, the performance of the composites of PEDOT with nanomaterials (mono and bi-metallic nanoparticles, graphene and nanotubes) has been thoroughly investigated in the last years because the incorporation of those nanostructures can significantly improve the sensing properties of the pristine polymer [3,4]. However, to the best of our knowledge the effect of the content of hollow PdAu nanoparticles in PEDOT composites for the detection of nitrite, an important environmental pollutant, has not been reported before.In this work, PEDOT films were prepared by cyclic voltammetry and under amperometric and potentiostatic conditions from a solution of EDOT, LiClO4 and SDS (sodium dodecyl suphate). The films were characterized by scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). 500 nm- and 300 nm-thick PEDOT films deposited on glassy carbon were used for the electrochemical detection of nitrite by differential pulse voltammetry. 500 nm-thick films shown a higher sensitivity towards NO2 - ions (0.027 μA μM-1). Hollow nanoparticles of gold and palladium were synthesized by a galvanic replacement reaction using Na2PdCl4. PEDOT films were codeposited with the hollow PdAu nanoparticles at constant potential. The performance of the composites with different contents of the bimetallic nanoparticles (3,6,12,15,24 and 30% of the total mass of nanoparticles) were evaluated for the detection of nitrite ions in the range of 50 to 250 μM nitrite. All composites exhibited a higher performance in comparison to PEDOT films mainly in the range of 50 to 112.5 μM.Figure 1.- SEM PEDOT films produced by (a) potentiostatic deposition, (b) constant current, (c) cyclic voltammetry and (d) DPV curves of nitrite detection with PEDOT + 15% mass percent of PdAu nanoparticles suspension Figure 1

Regulation mechanism of magnetic field on non-Newtonian melting and energy storage performance of metal foam composite nano-enhanced phase change materials

A numerical study is conduced to explore regulation mechanism of magnetic field on melting heat transfer and energy storage performance of nano-enhanced phase change material (NEPCM) composited with metal foam. The enthalpy-porosity method, Darcy-Forchheimer model and local thermal non-equilibrium model are used to describe melting process, flow in porous media and coupling heat transfer, respectively. The proposed model is then verified by experiments using thermochromic liquid crystal thermometry. Effects of nanoparticles mass fraction (0%≤Φwt≤5%), magnetic number (0≤Mn≤7×106), and Rayleigh number (104≤Ra≤106) on the non-Newtonian fluids flow, melting heat transfer and energy storage characteristics are illustrated and discussed. Results show that the addition of Fe3O4 nanoparticles can effectively promote melting and induce non-Newtonian effect of molten NEPCM, but Φwt has no significant influence on the heat transfer. With the increase of Mn, the suppression effect of magnetic field on the whole melting process of NEPCM enhances at moderate Ra = 105, and natural convection is fully developed with a “force bridge” phenomenon of Kelvin force. For lower Ra (=104), natural convection becomes weaker and magnetic field presents a “force loop” phenomenon. For larger Ra (=106), natural convective heat transfer has absolute predominance and the suppression effect of magnetic field can be ignored. Moreover, the increase of Φwt and Ra have obvious positive contributions to heat storage and heat storage efficiency. At low Ra, the suppression effect of magnetic field on heat storage and total melting time leads to decrease in energy storage efficiency.

Numerical analysis of concentration-dependent physical properties and bioconvection for Williamson nanofluid flow due to stretching/ shrinking sheet

In this paper, an investigation into Williamson nanofluid stagnation point flow of nano-biofilm over a stretching/ shrinking sheet with chemical reaction is performed. Moreover, the impact of cylindrical-shaped nanoparticles, activation energy, and bioconvection has been considered. The fluid’s fluctuating transport properties (dynamic viscosity, heat conductivity, nanoparticle mass diffusivity) and microorganism diffusivity are evaluated. The nonlinear systems of partial differential equations are transformed into nonlinear differential equations via the implementation of similarity transformations. The shooting approach and RK-4 technique are used for this investigation. The impacts of various fluid transport characteristics and various factors on patterns of velocity, temperature, the concentration of nanoparticles, and motile density are described. The Brownian motion, heat source and thermophoresis parameters all lead to a more consistent temperature profile being observed. It is seen that concentration-dependent properties decrease the velocity profile while the temperature, concentration, and motile density profiles increase. Also, the physical quantities decrease with the rising values of concentration-dependent properties.

Swirling bioconvective nanofluid flow from a spinning stretchable disk in a permeable medium

ABSTRACT Medical engineering is increasingly deploying nanotechnology and bio-inspired designs in the 21st century. Motivated by studying the spin coating of bio-nanofluid materials, gyrotactic bioconvection nanofluid swirling coating flow from a spinning disk to an isotropic permeable medium is analysed. The balance equations for mass, momentum, thermal, concentration and microorganism species including blowing effects are transformed into ordinary differential equations and then the solutions are obtained numerically through MATLAB bvp4c quadrature. These solutions are further validated with Adomian decomposition method (ADM). Increasing radial momentum slip reduces the radial skin friction and increasing tangential slip suppresses the tangential skin friction. Nusselt number, nanoparticle Sherwood number and micro-organism density number gradient are, respectively, decreased with increment in thermal slip, nanoparticle mass slip and micro-organism slip factors. Combinations of bioconvection and nanofluids provide excellent advantages in designing anti-bacterial and resilient bio-coatings for many devices.

Daytime radiative cooling capacity of nanoparticle on thermoplastic polyurethane (TPU) film

Radiative cooling, which does not entail any energy consumption, has received considerable attention as a promising, practical, and sustainable solution to heatwaves. This study investigated single layer nanoparticles–polymer films that reflected sunlight and emitted radiation through atmospheric windows. In this paper, the fundamental principles of Mie theory, the cooling power model, and the thermal balance model of metamaterial films were first introduced. Then, the influence of fabrication parameters (nanoparticle materials, mass fractions, and thicknesses) to the reflectivity in solar band was experimentally explained. An increase in the mass fraction enhanced the reflectivity corresponding to the stretching vibration regions of CH, NH, and OH, while an increase in the thickness improved the reflectivity at non-absorption bands. Laboratory measurements indicated that the combination of TiO2, a fluorescent brightener, and a far-infrared ceramic powder on 100 μm thermoplastic polyurethane film achieved excellent solar reflectivity of 92.2 % and infrared emissivity of 96.1 %. Experimental testing and Fluent simulation showed that the film achieved a substantial cooling capacity in both Beijing and Tianjin. Under a transparent atmospheric window, it exhibited a subambient temperature of 3.7 °C when the air temperature reached its peak. The maximum daytime and night-time subambient temperature were 13.4 °C and 14 °C respectively.