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Perspective of multiple slips on 3D flow of Al2O3TiO2CuO/H2O ternary nanofluid past an extending surface due to non-linear thermal radiation
A mathematical model is constructed under the slip flow of a Newtonian fluid based on certain assumptions. Such a mathematical model of ternary nanofluid flow is handled by invoking similarity solutions for governing equations. The obtained system of nonlinear equations is solved numerically by utilizing the fourth-fifth order RungeKutta-Fehlberg method. The consequences of distinguished parameters on fluid flow are analyzed in detail through the plotted graphic visuals. Physical quantities such as Nusselt number and skin-fraction coefficient are considered numerically by tables. The results indicated that the mixed convection parameter favors the flow whereas the x-direction velocity slip reduces the velocity. Furthermore, it is observed that the temperature of the nanofluid is increased for the higher values of radiation. The presence of a heat source enhances the temperature and that of a heat sink diminishes the temperature. It is found that the heat conduction capability is more in ternary nanofluid than the hybrid and monophase nanofluids. 2022 Informa UK Limited, trading as Taylor & Francis Group. -
Quartic autocatalysis of homogeneous and heterogeneous reactions in the bioconvective flow of radiating micropolar nanofluid between parallel plates
This study deals with the quartic autocatalysis of homogeneousheterogeneous chemical reaction that occurs in the bioconvective flow of micropolar nanofluid between two horizontally parallel plates. The quartic autocatalysis is found to be more effective than cubic autocatalysis since the concentration of the homogeneous species is substantially high. The upper plate is assumed to be in motion and the lower plate is kept stationary. Such a flow of micropolar fluid finds application in the pharmaceutical industry, microbial enhanced oil recovery, hydrodynamical machines, chemical processing,and so forth. The governing equations for this flow are in the form of the partial differential equation and their corresponding similarity transformation is obtained through Lie group analysis. The governing equations are further transformed to coupled nonlinear differential equations that are linearized through the Successive linearization method and are solved using the Chebyshev Collocation method. The effects of various parameters, such as micropolar coupling parameter, spin gradient parameter, reaction rates, and so forth, are analyzed. It is observed that the fluid flows with a greater velocity away from the channel walls, whereasnear the channel walls the velocity decreases with an increase in the coupling parameter. Furthermore, the spin parameter increases the spin gradient viscosity that reduces the microrotation of particles that further decreases the microrotation profile. 2021 Wiley Periodicals LLC -
Bioconvection in buoyancy induced flow of Williamson nanofluid over a Riga Plate-DTM-Padapproach
The buoyancy induced flow of Williamson nanofluid containing Gyrotactic microorganisms along a vertical Riga plate has been investigated. This research aims at analysing the heat and mass transfer characteristics of Williamson Nanofluid in the presence of Gyrotactic microorganisms that helps in avoiding the agglomeration of nanoparticles during the nanofluid flow. The Gyrotactic microorganisms act as active mixers that help in stabilising the nanoparticles in the suspension. Also, the movement of these cells gives rise to a macro phenomenon called bioconvection that helps in preventing the agglomeration of nanoparticles. Furthermore, the magnetic field generated due to the flow of nanofluid is considered in addition to Thermophoresis and Brownian Motion to make the results more appropriate. Buongiornos Model has been incorporated to frame the system of equations that govern the fluid flow. Later, lie group analysis is performed to transform these equations into ordinary differential equations that are further solved using the differential transform method with Padapproximant. It is observed that the Lorentz force generated by the Riga plate in parallel to the flow helps in increasing the velocity of the nanofluid. It is also noticed that bioconvection reduces the flow speed and enhances the heat transfer rate. 2020 by American Scientific Publishers All rights reserved. -
Magneto convective flow of casson nanofluid due to Stefan blowing in the presence of bio-active mixers
The induced magnetic field for three-dimensional bio-convective flow of Casson nanofluid containing gyrotactic microorganisms along a vertical stretching sheet is investigated. The movement of these microorganisms cause bioconvection and they act as bio-active mixers that help in stabilising the nanoparticles in the suspension. The two forces, Thermophoresis and Brownian motion are incorporated in the Mathematical model along with Stefan blowing. The resulting model is transformed to ordinary differential equations using similarity transformations and are solved using (Formula presented.) method. The Velocity, Induced Magnetic field, Temperature, Concentration of Nanoparticles, and Motile density profiles are interpreted graphically. It is observed that the Casson parameter decreases the flow velocity and enhances the temperature, concentration, and motile density profiles and also it is noticed that the blowing enhances the nanofluid profiles whereas, suction diminishes the nanofluid profiles. On the other hand, it is perceived that the rate of heat conduction is enhanced with Thermophoresis and Brownian motion. IMechE 2021. -
The three-dimensional bioconvective flow of Sisko nanofluid under Robin's conditions
The proposed model investigates three-dimensional bioconvective Sisko nanofluid flow under Robin's conditions. The Sisko nanofluid has versatile implications in drilling fluids, cement slurries, waterborne coatings, and so on. Furthermore, the inclusion of gyrotactic microorganisms prevents the deposition and agglomeration of the nanoparticles in the base fluid. Buongiorno's model is included to explore the behavior of Brownian motion and thermophoretic factors. The energy and mass transmissions along with the gyrotactic microorganism density are illustrated by the partial differential expression system with Robin's conditions. These are further reframed into an ordinary differential equation system with the aid of similarity transformation. The developing model is tackled by using the MAPLE inbuilt package BVP. The nanofluid acts as a goodcooling agent for higher values of the thermophoresis parameter. Furthermore, the pseudoplastic nanofluid performs better than the dilatant nanofluid. The developed model is very useful in energy production and engineering products. 2021 Wiley Periodicals LLC -
Three dimensional mixed convection flow of hybrid casson nanofluid past a non-linear stretching surface: A modified Buongiorno's model aspects
The purpose of this study is to determine the role of mixed convection, Brownian motion, and thermophoresis in the dynamics of Casson hybrid nanofluid in a bidirectional nonlinear stretching sheet. For the flow model, a combination of Tiwari and Das models, as well as Buongiornos model, is considered. The thermophysical characteristics of Gr, TiO2, and blood are employed. With the assistance of relevant similarity transformation, the describing flow equations of a Casson hybrid nanofluid model are reformed in the form of a system with a single independent variable. The solution for these equations is obtained using the RKF-45 approach. The velocity, temperature, and concentration fields are visually developed for both linear and non-linear stretching sheets, and the implications of the major parameters are presented in detail. It is clear from the current investigation that heat and mass transfer characteristics of fluid are better in the case of linear stretching than non-linear stretching. Furthermore, the mixed convection parameter is found to enhance the fluid flow velocity. However, the trend is quite opposite in the thermal and concentration fields. Meanwhile, the increase in the yield stress caused due to the rise in the Casson parameter decreases the flow velocity. 2021 Elsevier Ltd -
Bioconvection of a radiating hybrid nanofluid past a thin needle in the presence of heterogeneous-homogeneous chemical reaction
The photocatalytic nature of TiO2 finds applications in medicinal field to kill cancer cells, bacteria, and viruses under mild ultraviolet illumination and the antibacterial characteristic of Ag makes the composition Ag - TiO2 applicable for various purposes. It can also be used in other engineering appliances and industries such as humidity sensor, coolants, and in footwear industry. Hence, this study deals with the analysis of the effects of magnetic field, thermal radiation, and quartic autocatalysis of heterogeneous-homogeneous reaction in an electrically conducting Ag - TiO2 - H2O hybrid nanofluid. Furthermore, the gyrotactic microorganisms are used as active mixers to prevent agglomeration and sedimentation of TiO2 that occurs due to its hydrophobic nature. The mathematical model takes the form of partial differential equations with viscosity and thermal conductivity being the functions of volume fraction. These equations are converted to ordinary differential equations by using similarity transformation and are solved by RKF-45 method with the aid of shooting method. It is observed that the increase in the size of the needle enhances the overall performance of the hybrid nanofluid. Furthermore, the temperature of the hybrid nanofluid increases with the increase in volume fraction. It is observed that the friction produced by the Lorentz force increases the temperature of the nanofluid. It is further observed that the heterogeneous reaction parameter has more significant effect on the concentration of bulk fluid than the homogeneous reaction parameter. Copyright 2021 by ASME. -
Numerical simulation of JeffreyHamel flow of nanofluid in the presence of gyrotactic microorganisms
The nonlinear differential equations play a prominent role in mathematically describing many phenomena that occur in our world. A similar set of equations appear in this paper that govern the nanofluid flow between two non-parallel walls in the presence of gyrotactic microorganisms that are responsible for bioconvection. These microorganisms ensure the safety of the appliance by avoiding the accumulation of nanoparticles and the movement of these nanoparticles within the fluid experiences major slip mechanisms as discussed by Buongiorno. Further, the orientation of the channel is described by the parameter ? and based on this parameter, the channel is said to be converging if (Formula presented.) and the channel is diverging if (Formula presented.). The case when (Formula presented.) corresponds to a channel with parallel walls, hence this case is ignored. Following these assumptions, the set of governing equations thus formed are made dimensionless and further solved by the Differential Transformation Method (DTM) and the outcomes are discussed through graphs. The analysis is performed for both converging and diverging orientations of the channel. The results indicate that the temperature and the concentration profiles increase with the increase in Brownian motion parameters in both divergent and convergent channels. Meanwhile, the increase in Reynolds number decreases the temperature of the nanofluid. Through the simulation, it was observed that the heat flow is taking place along the isothermal planes in the case of the diverging channel but it was uniform in the domain of the converging channel. 2021 Informa UK Limited, trading as Taylor & Francis Group. -
FAMILY OF CONGRUENCES FOR (2, ?)?REGULAR BIPARTITION TRIPLES
Though congruences have their limitations, they have significant importance in the field of number theory and helps in proving many interesting results. Thus, this article has adopted the technique and properties of congruences to identify and prove a set of congruent properties for integer partition. The partition of a positive integer is a way of expressing the number as a sum of positive integers. One such partitions known as regular bipartition triple are discussed in this article. New congruences modulo even integers and modulo prime (p ? 5) powers are derived for (2, ?)?regular bipartition triples. Also infinite families of congruences modulo 2 for some (2, ?)?regular bipartition triples are derived. The theorems stated in this article are proved using the q?series notation and some of the prominent results such as Eulers pentagonal number theorem and Jacobis triple product identities. There are certain lemmas which are derived using these results that help in proving the major results of this article. 2022, RAMANUJAN SOCIETY OF MATHEMATICS AND MATHEMATICAL SCIENCES. All rights reserved. -
A FAMILY OF CONGRUENCES FOR (2, ?)?REGULAR BIPARTITIONS
The congruence of certain restricted partition functions known as regular bipartition is discussed in this paper. We particularly investigate the (2, ?)-regular bipartitions of n, denoted by B2,? (n), and establish certain congruences for B2,? (n) when ? ? 3. We derive infinite families of congruences modulo 4 for the (2, 3)-regular bipartition. We also obtain a generalisation of the regular bipartition for modulo p and p2. Indian Mathematical Society, 2022. -
Impact of bioconvection on the free stream flow of a pseudoplastic nanofluid past a rotating cone
In the current work, the repercussions of Brownian motion and thermophoresis on the three-dimensional free stream flow of tangent hyperbolic (pseudoplastic) nanofluid past a rotating cone are explored. The tangent hyperbolic model expresses the characteristics of a shear-thinning nanofluid. Furthermore, oxytactic microorganisms were used as mixers to actively stabilize the nanoparticles. The movement of these microorganisms within the nanofluid gives rise to a major phenomenon termed bioconvection. The flow of nanofluid past a rotating cone finds applications in the field of nuclear reactors, biomedical applications, solar power collectors, steam generators, and so on. The mathematical model is designed using Buongiorno's model that describes the two major slip mechanisms experienced by the nanoparticles moving within a fluid namely thermophoretic force and Brownian motion. The model thus formed is nondimensionalized using the apt similarity transformation. The resulting system is solved by the (Formula presented.) technique by adapting the shooting method. The velocity, temperature, concentration, and motile density profiles are graphically interpreted for different flow parameters involved in the study. It was observed that thermophoresis reduces concentration and enhances the temperature whereas Brownian motion enhanced both temperature and concentration profiles. Also, the increase in the mixed convection parameter effectively decreased the temperature of the nanofluid. 2022 Wiley Periodicals LLC. -
Flow of nanofluid past a stretching cylinder subject to Thompson and Troian slip in the presence of gyrotactic microorganisms
Incorporating the Thompson and Troian slip condition, this work studies the bioconvective flow of a nanofluid past a vertically stretching cylinder. The Thompson and Troian slip deals with the molecular scale interactions at the solidfluid interface, which plays a pivotal role in the fluid flow analysis. This study helps in understanding the behaviours of fluid flow in the presence of non-linear slip past a vertically stretching cylinder. The corresponding partial differential equations (PDEs) for momentum, energy, concentration of nanoparticles, and concentration of microbes are developed using Buongiornos model. A suitable similarity transformation is then applied to these PDEs, converting them into a set of ordinary differential equations (ODEs). The RungeKuttaFehlberg (RKF-45) method is utilized to calculate the numerical solution of the resulting ODE problem. The results demonstrate that the interaction of slip conditions, viscous dissipation, heat source, and bioconvection causes complex flow patterns and heat transfer characteristics. These observations are extremely relevant for applications including better oil recovery procedures, biomedical engineering, and microfluidic devices where exact control over nanofluid behaviour is necessary. Some of the major observations of the study include the enhancement of the temperature in the nanofluid for higher Eckert numbers, control of fluid flow through an external magnetic field, and Peclet number significantly decreased the motile density in the nanofluid. The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024. -
Polypyrrole/ silver/graphene ternary nanocomposite synthesis and study on photocatalytic property in degrading Congo red dye under visible light
In this report, a simple chemical synthesis of polypyrrole/silver/graphene (Ppy/Ag/Gr) ternary nanocomposites with varying concentrations of graphene are described. The XRD spectra of the samples polypyrrole/silver (Ppy/Ag) and Ppy/Ag/Gr show all the peaks of the face-centered cubic structure of silver. A broad peak between 10 and 20 and a peak at 26.7 corresponds to Ppy and graphene respectively. Using FTIR, and UVVis. spectroscopies the interaction between polypyrrole, silver, and graphene were studied. In our work, we explored the photocatalytic property of the synthesised samples by using them to degrade the aqueous solution of a cancer-causing dye, Congo red. The percentage degradation of Congo red dye using the sample Ppy/Ag/Gr (0.5 wt.%) is obtained as 96% and the reaction rate calculated is 0.162/min., greater than that of Ppy/Ag and Ppy/Gr binary composites. Thus, the addition of the optimum concentration of graphene into Ppy/Ag enhanced its photocatalytic property. The BET analysis shows an increased surface area for the sample Ppy/Ag/Gr (0.5 wt.%) and the reason for the enhancement of photocatalysis with this sample is confirmed since it is a surface-dependent property. The biodegradability of the dye solution was investigated by Chemical Oxygen Demand (COD) analysis and the COD value was reduced from 432 mg/L to 216 mg/L after 20 min of irradiation of light. 2023 -
Thermal diffusivity study of one-pot synthesised polypyrrole silver nanocomposite by thermal lens method
We are reporting the results of our exploration of the thermal lens method to determine the thermal diffusivity of Ppy and Ppy/Ag nanocomposites synthesised by simple, cost effective in situ chemical oxidative polymerisation. EDAX spectrum confirms the presence of silver in the samples. Raman analysis shows that the increase in the concentration of silver in composite results in an increase in the conjugation length of the samples. We have adopted the dual-beam pump-probe technique to determine the thermal diffusivity of polypyrrole and polypyrrole silver nanocomposite with varying silver concentrations. We report suppression of thermal diffusivity of polypyrrole with the addition of a small concentration of silver and an enhanced thermal diffusivity with an increase in the concentration of silver with ethanol as the base fluid. Increased thermal diffusivity of the samples makes them suitable for use as coolants. 2022 Elsevier Ltd -
Polypyrrole- silver nanocomposite for enhanced photocatalytic degradation of methylene blue under sunlight irradiation
Polypyrrole (Ppy) -Silver nanocomposite samples have been synthesised by chemical oxidative polymerisation. The characteristic peaks of face centered cubic (fcc) structure of silver in XRD confirmed its presence in Ppy. Shift in NH stretching frequency observed in FTIR spectroscopy revealed the coordination of silver into Ppy. The photocatalytic activity of the samples was studied by photocatalytic degradation of the aqueous solution of methylene blue (MB) under sunlight. The presence of Ag in polypyrrole (Ppy) enhanced its photocatalytic activity with respect to the reported values which further increased on increasing the silver concentration. 2021 Elsevier B.V. -
Leveraging digital yarn dyeing for colour consistency in apparel weaving
When compared to traditional processes, digital yarn dyeing provides substantial benefits in terms of color control, versatility, and environmental impact. However, technological obstacles and constraints exist. The promise of digital dyeing may be realized by carefully selecting technology, optimizing ink consumption, and adopting stringent quality control methods, resulting in improved colour constancy and a more sustainable textile sector. -
Biosynthesis of ZnFe2O4@Ag hybrid nanocomposites for degradation of 2,4-Dichlorophenoxyacetic acid herbicide
This work demonstrates recent advancements in the phytosynthetic and environmentally friendly method of preparing ZnFe2O4 and ZnFe2O4@Ag hybrid nanocomposites using Pedalium murex L leaf extract as a stabilizing and reducing agent. The synthesized nanocomposite was characterized with UVvis, FTIR, TGA/DSC, XRD, FE-SEM, and EDX to investigate the electronic as well as morphological properties. Moreover, the photocatalytic behaviour of ZnFe2O4 and ZnFe2O4@Ag hybrid nanocomposites was evaluated with a breakdown of 2,4-dichlorophenoxyacetic acid (2,4-DPA) by exposing to UVVis light. The results obtained suggest that ZnFe2O4@Ag hybrid nanocomposite exhibited photocatalytic activity for the degradation of 2,4-DPA by approximately 94% in 60 min compared to ZnFe2O4. The hybrid nanostructure of ZnFe2O4@Ag significantly promoted charge transfer and prevented electron and hole recombination resulting in the enhancement of photocatalytic activity. Furthermore, ZnFe2O4@Ag nanocomposite showed the fair recyclable capacity for up to five catalytic cycles with an acceptable degradation percentage of 2,4-DPA. The findings of this study identify efficient charge transfer factor as a major contributor to the catalytic activity, with promising possibilities for the design of environmental remediation nanocomposite for harmful contaminants. 2023 The Author(s) -
Multifunctional characteristics of biosynthesized CoFe2O4@Ag nanocomposite by photocatalytic, antibacterial and cytotoxic applications
Carissa carandas, a traditional medicinal herb with a high concentration of antioxidant phytochemicals, has been used for thousands of years in the Ayurveda, Unani, and homoeopathic schools of medicine. By employing Carissa carandas bark extract as a reducing and capping agent in green biosynthesis, we extend this conventional application to produce CoFe2O4 and CoFe2O4@Ag nanocomposite. A variety of techniques have been used to characterize the synthesised nanocomposite, including UVVis, FTIR, XRD, FESEM, EDX, and BET. The CoFe2O4 and CoFe2O4@Ag nanocomposite demonstrated promising antibacterial action against human bacterial pathogens like B. subtilis and S. aureus as gram positive and P. aeruginosa and E. coli as gram negative with inhibition zones of 24.3 0.57, 17.4 0.75 and 20.5 0.5, 19.8 1.6 mm respectively, and the obtained results were superior to the nanocomposite without silver. Moreover, in-vitro cytotoxicity effects of biosynthesized CoFe2O4 and CoFe2O4@Ag were performed on the human breast cancer cell MCF-7. It was found that the MCF-7 cells' 50% inhibitory concentration (IC50) was 60 ?g/mL. Additionally, biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposite was used to demonstrate the photocatalytic eradication of Rhodamine Blue (RhB). Due to the addition of Ag, which increases surface area, conductivity, and increased charge carrier separation, the CoFe2O4@Ag nanocomposite exhibits a high percentage of photocatalytic degradation of ? 98% within 35 min under UV light irradiation. The photocatalytic performance of as-synthesised nanocomposite was evaluated using dye degradation-adsorption in both natural light and dark condition. Under dark conditions, it was found that 2 mg mL?1 CoFe2O4@Ag in RhB aqueous solution (5 ppm) causes dye adsorption in 30 min with an effectiveness of 72%. Consequently, it is anticipated that the CoFe2O4@Ag nanocomposite will be a promising photocatalyst and possibly a noble material for environmental remediation applications. 2023 Elsevier Ltd -
Biosynthesis of CuFe2O4@Ag hybrid nanocomposite: Ultrasensitive detection and catalytic reduction of 4-nitrophenol
Due to the dearth of extremely capable, sensitive, and stable catalysts, the efficient detection and catalytic removal of 4-nitrophenol (4-NP) in industrial wastewater remains a serious challenge. The detection and determination of 4-nitrophenol (4-NP) presence in the environment is a matter of paramount importance because it is a high-priority hazardous pollutant that can affect people, animals, and plants. Here, we present a promising and economically viable green synthetic route for fabricating CuFe2O4 and CuFe2O4@Ag hybrid nanocomposites from the leaf extract of Senna didymobotrya. The UVVis, FTIR, XRD, FE-SEM, EDXA, BET and VSM analysis were performed to characterize the synthesis of CuFe2O4@Ag nanocomposite. To evaluate the electrocatalytic capacity of CuFe2O4@Ag, electrochemical sensing stratergy was performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modified CuFe2O4@Ag glassy carbon electrode (GCE) (CuFe2O4@Ag/GCE) demonstrated a linear response in the range of 0.01-15 ?g/ml (71 nm-107 ?M) and the ability to detect 4-NP at low concentration (0.006 ?g/ml (43 nM)). Due to the increased surface area of CuFe2O4@Ag/GCE by ? 1.5-fold, a greater cathodic current response (-16 ?A/cm2) at a low potential of -0.81 V was observed compared to CuFe2O4/GCE alone for the detection of 4-NP. Additonally, CuFe2O4@Ag showed excellent reduction ability towards 4-NP using NaBH4 with an efficiency of 96.4 % which was higher than the CuFe2O4 (only 87.3 %) in 12 min due to the synergistic relationship among Ag NPs and CuFe2O4 nanostructures. The outcomes from this study shows that the bi-functional electrocatalyst holds vast potential for environmental remediation. 2024 The Author(s) -
Classification and characterization using HCT/HFOSC spectra of carbon stars selected from the HES survey
We present results from the analysis of 88 carbon stars selected from Hamburg/ESO (HES) survey using low-resolution spectra (R ?1330 & 2190). The spectra were obtained with the Himalayan Faint Object Spectrograph Camera (HFOSC) attached to the 2-m Himalayan Chandra Telescope (HCT). Using well-defined spectral criteria based on the strength of carbon molecular bands, the stars are classified into different groups. In our sample, we have identified 53 CH stars, four C-R stars, and two C-N type stars. Twenty-nine stars could not be classified due to the absence of prominent C2 molecular bands in their spectra. We could derive the atmospheric parameters for 36 stars. The surface temperature was determined using photometric calibrations and synthesis of the H-alpha line profile. The surface gravity log g estimates are obtained using parallax estimates from the Gaia DR3 database whenever possible. Microturbulent velocity (?) was derived using calibration equation of log g & ? . We could determine metallicity for 48 objects from near-infrared Ca II triplet features using calibration equations. The derived metallicity ranges from ?0.43 ? [Fe/H] ? ?3.49. Nineteen objects were found to be metal-poor ([Fe/H] ? ?1), 14 very metal-poor ([Fe/H] ? ?2), and five extremely metal-poor ([Fe/H] ? ?3.0) stars. Eleven objects were found to have a metallicity in the range ?0.43 ? [Fe/H] ? ?0.97. We could derive the carbon abundance for 25 objects using the spectrum synthesis calculation of the C2 band around 5165 The most metal-poor objects found will make important targets for follow-up detailed chemical composition studies based on high-resolution spectroscopy, and are likely to provide insight into the Galactic chemical evolution. 2024, The Author(s), under exclusive licence to Springer Nature B.V.