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High surface area Nanoflakes of P-gC3N4 photocatalyst loaded with Ag nanoparticle with intraplanar and interplanar charge separation for environmental remediation
The photocatalytic performance of gC3N4 is majorly restricted by insufficient collection of photogenerated charges on the surface during reaction due to highly dense stacking of lamellar structures with lateral size ranging in microns. This deficiency can be overcome by forming thin nanoflakes by systematically breaking the weak bonds that hold the gC3N4 framework without destroying the basic heptazine unit. With this aim, herein, a combination of three different strategies was implemented to design and develop, Ag-loaded and P-doped gC3N4 nanoflakes (Ag3-P1-NF-gC3N4). Using a systematic synthesis method, bulk gC3N4 was first converted into thin nanosheets, followed by fragmentation into nanoflakes, with a planar size up to 100 nm. P doping to replace the corner C atoms in the gC3N4 matrix (forming P[sbnd]N bonds) and intercalation of plasmonic Ag nanoparticles within the interlayers also assists in the bifurcation of the stacked layers and formation of nanoflake morphology. These strategies result in a significant increase in BET surface area to ?196 m2/g from 12 m2/g of bulk gC3N4. Improved inter-planar and intra-planar charge mobility was recorded as a result of the reduced sizes. Doping with P also causes higher absorption of the visible spectrum in gC3N4 while the formation of heterojunction with Ag nanoparticles induces efficient separation of photo-generated charges. All these promoting photo-physical properties lead to an outstanding photocatalytic activity towards degradation of aqueous pollutants with reaction rates ?20 times higher than bulk gC3N4. Complete mineralization of the pollutant and formation of non-toxic byproducts was also confirmed with suitable chromatography techniques. 2020 Elsevier B.V. -
Ag Ions Versus Ag Nanoparticle-Embedded Glass for Antimicrobial Activity Under Light
Incorporating silver nanoparticles (NPs) into a host material has been recognized to limit the release of Ag+ ions, yet their efficacy in neutralizing nearby microorganisms remains uncertain. This study aims to compare the toxicity of Ag+ ions versus the plasmonic effect of Ag NPs within a glass matrix, assessing their respective killing efficiency and mechanisms against microorganisms. To achieve this objective, a simple ion exchange technique was employed to embed glass with silver ions, nanoclusters (NCs), or NPs, which was confirmed by UVVis-NIR spectrometer, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The biocidal action of these Ag species on model Escherichia coli (E. coli) bacteria was investigated in the absence and presence of visible light. The findings revealed that in the absence of light, plasmonic Ag NPs were less toxic to E. coli compared to Ag+ ions due to the predominant release of Ag+ ions dictating the antibacterial effect. However, exposure to visible light triggered the plasmonic effect in Ag NPs to disintegrate 100% E. coli in 1h compared to Ag+ ions (68%) owing to the localized heating around the Ag NPs, facilitated by surface plasmon resonance relaxation. The cell morphology investigated by Bio-AFM assisted in unraveling the mechanism leading to bacterial cell damage. Overall, this study demonstrates the sustained disinfection capability of Ag NPs embedded in glass without significant leaching, emphasizing their potential in prolonged antimicrobial applications. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024. -
Assessing performance of alkali-activated bricks incorporated with processed surgical masks
Since last few years the world is facing tremendous surge in the use of surgical masks due to the COVID19 pandemic. The uncontrolled disposal of surgical masks in the environment will pose serious threat to the living organisms due to plastic pollution. On the other hand, the construction industry is hugely dependent on natural resources, leading to increase in carbon footprint. Therefore, it necessary to investigate novel construction materials with sustainability perspective. In present study, alkali-activated bricks were synthesized with rice husk ash (RHA), ground granulated blast furnace slag (GGBFS), sand, and sodium silicate (SS). To this, processed surgical masks (PSM) were added in varying doses of 0%, 1%, 2%, 3%, and 4% by volume of the mix. The results revealed that addition of PSM significantly improved the strength properties of the bricks with a maximum compressive strength of 6.85 MPa at inclusion of 4% PSM. At the same time, it has reduced the density of bricks with a minimum value of 1.54 g/cm3 at inclusion of 4% PSM. The incorporation of PSM has slightly increased the water absorption and porosity of the bricks, with a maximum increase of 4.76% and 7.75% for bricks with 4% PSM, when compared to bricks with 0% PSM, respectively. The accelerated ageing test showed that after three cycles of wetting and drying the bricks exhibited loss in compressive strength in the range of 55.2%58.6%. The microstructure results revealed the bridging effect of fibrous mask particles in improving the load transfer in polymer matrix, and thereby reducing the brittle tensile failure in bricks. The pushover analysis showed the benefit of PSM in improving the performance of the infill walls due to improvement in brick strength and reduction in its self-weight, and therefore, it can be considered as a potential material for use in construction of buildings in seismically vulnerable areas. 2023 The Author(s) -
Recycled Surgical Mask Waste as a Resource Material in Sustainable Geopolymer Bricks
With the advent of the COVID-19 pandemic, the global consumption of single-use surgical masks has risen immensely, and it is expected to grow in the coming years. Simultaneously, the disposal of surgical masks in the environment has caused plastic pollution, and therefore, it is exigent to find innovative ways to handle this problem. In this study, surgical masks were processed in a laboratory using the mechanical grinding method to obtain recycled surgical masks (RSM). The RSM was added in doses of 0%, 1%, 2%, 3%, and 4% by volume of geopolymer bricks, which were synthesized with ground granulated blast furnace slag (GGBS), rice husk ash (RHA), sand, and sodium silicate (Na2SiO3) at ambient conditions for a duration of 28 days. The developed bricks were tested for compressive strength, flexural strength, density, water absorption, efflorescence, and drying shrinkage. The results of the study reveal that compressive strength and flexural strength improved with the inclusion of RSM in the bricks. The highest values of compressive strength and flexural strength were 5.97 MPa and 1.62 MPa for bricks with 4% RSM, respectively. Further, a reduction in the self-weight of the bricks was noticed with an increase in RSM. There was no pronounced effect of RSM on the water absorption and efflorescence properties. However, the RSM played a role in reducing the drying shrinkage of the bricks. The sustainability analysis divulges the catalytic role of RSM in improving material performance, thereby proving to be a potential candidate for low-carbon material in the construction industry. 2023 by the authors. -
Sensitivity computation of nonlinear convective heat transfer in hybrid nanomaterial between two concentric cylinders with irregular heat sources
Heat exchangers, hot rolling, heat storage systems, and nuclear power plants utilize hybrid nanoliquid flow through an annulus for heat transport. The linear Boussinesq approximation is no longer suitable as these devices work at both moderate and extremely high temperatures. Hence, the salient features of quadratic convection on the hybrid nanoliquid flow in an inclined porous annulus are analyzed. The heat transport phenomenon is examined with an exponential space-related heat source (ESHS), the convective boundary conditions, and temperature-related heat source (THS). The significance of various shapes of nanoparticles (blades, spherical, platelets, bricks, and cylinders) on the heat and fluid flow characteristics has been explored. The complicated governing equations are solved numerically. Additionally, a statistical study (response surface methodology (RSM) and sensitivity analysis) is performed. The consequence of key parameters on the non-dimensional velocity, skin friction coefficient, temperature, and Nusselt number fields are presented through two-dimensional and surface plots. The irregular heat sources increase the magnitude of velocity and temperature fields. The quadratic and mixed convection mechanism favors the flow structure. The temperature and velocity fields are greater for platelet-shaped nanoparticles followed by cylinder, brick, and spherical-shaped nanoparticles. Further, the Nusselt number is more influenced by THS and less by the total nanoparticle volume fraction 2021 Elsevier Ltd -
Heat transport of hybrid nanomaterial in an annulus with quadratic Boussinesq approximation
The convective heat transfer of hybrid nanoliquids within a concentric annulus has wide engineering applications such as chemical industries, solar collectors, gas turbines, heat exchangers, nuclear reactors, and electronic component cooling due to their high heat transport rate. Hence, in this study, the characteristics of the heat transport mechanism in an annulus filled with the Ag-MgO/H2O hybrid nanoliquid under the influence of quadratic thermal radiation and quadratic convection are analyzed. The non-uniform heat source/sink and induced magnetic field mechanisms are used to govern the basic equations concerning the transport of the composite nanoliquid. The dependency of the Nusselt number on the effective parameters (thermal radiation, nonlinear convection, and temperature-dependent heat source/sink parameter) is examined through sensitivity analyses based on the response surface methodology (RSM) and the face-centered central composite design (CCD). The heat transport of the composite nanoliquid for the space-related heat source/sink is observed to be higher than that for the temperature-related heat source/sink. The mechanisms of quadratic convection and quadratic thermal radiation are favorable for the momentum of the nanoliquid. The heat transport rate is more sensitive towards quadratic thermal radiation. 2021, Shanghai University and Springer-Verlag GmbH Germany, part of Springer Nature. -
Significance of variable fluid properties on hybrid nanoliquid flow in a micro-annulus with quadratic convection and quadratic thermal radiation: Response surface methodology
Many engineering and manufacturing processes such as heat storage systems, nuclear power plants, and heat exchangers operate at high temperatures. The temperature gradient in these systems is significantly large so that the transport properties of the fluid are significantly influenced. In such cases considering the constant thermophysical properties for ambient liquid and adopting linear Boussinesq approximation become insignificant. Therefore, in this study, the quadratic convective flow of water-based Ag-MgO hybrid nanoliquid in a micro-annulus with variable viscosity and thermal conductivity is investigated under the temperature jump and velocity slip auxiliary conditions. The effects of quadratic Boussinesq approximation and quadratic Rosseland radiative heat are also addressed. The correlation for effective viscosity and thermal conductivity are modeled by employing the experimental work of Esfe and his collaborators (so-called Esfe Model). The nonlinear dimensionless governing equations are solved numerically using the finite difference method. Further, the sensitivity analysis using response surface methodology (RSM) is performed to enhance the understanding of heat transport behavior. The significance of various flow parameters involving in the current problem is analyzed through 2D and 3D-surface plots. This study portrays that the consequence of quadratic convection, velocity slip, and variable viscosity aspects are positively related to the growth of the momentum layer structure. The heat transport rate is found to be more dominated by quadratic radiation compared to the addition of nanoparticles and temperature variation aspect. The variable viscosity, quadratic convection, and quadratic thermal radiation mechanisms lead to higher skin friction. The thermal layer structure augments with the temperature variation aspect. Furthermore, the sensitivity of the Nusselt number to the addition of nanoparticles and quadratic radiation is always positive. 2021 Elsevier Ltd -
Sensitivity analysis of nonlinear radiated heat transport of hybrid nanoliquid in an annulus subjected to the nonlinear Boussinesq approximation
The main emphasis of the current study is to analyze the novel feature of the quadratic convective and nonlinear radiative flow of MHD hybrid nanoliquid (CuAl2O3H2O) in an annulus with sensitivity analysis. The significance of exponential space-related heat source, movement of annuli and a new radiation parameter corresponding to an asymptotic nature are also comprehended in the existing study. The dimensionless governing nonlinear equations are treated numerically by employing shooting technique. Impact of effective parameters on the flow and heat transport features has been scrutinized. The optimization procedure is implemented to analyze the influence of three effective parameters (1.5?Rf?5.5,1?QE?3and1%??Cu?3%) on skin friction and Nusselt number by utilizing response surface methodology and sensitivity analysis. The obtained results portray that the nonlinear convection parameter is more favorable for the skin friction coefficient. Further, a comparison of sensitivity depicts that the skin friction coefficient is more sensitive to Rf and QE, whereas Nusselt number is more sensitive to ?Cu. 2020, Akadiai Kiad Budapest, Hungary. -
Optimization and sensitivity analysis of heat transport of hybrid nanoliquid in an annulus with quadratic Boussinesq approximation and quadratic thermal radiation
The quadratic convective flow of hybrid nanoliquid in an annulus subjected to quadratic thermal radiation is studied for the first time. The impact of suction/injection and the uniform movement of the rings are considered. Nonlinear equations are handled numerically by adopting the shooting technique. An optimization procedure is performed by using response surface methodology. The maximum heat transport is observed for chosen values of effective parameters (thermal radiation parameter (5 ? Rt? 15) , temperature ratio parameter (1.1 ? ?w? 5.1) and nanoparticle volume fraction of copper (1 % ? ?Cu? 3 %)) at three different levels (low(? 1), middle(0) and high(+ 1)). In addition, a slope of the data point is evaluated for the friction coefficient and the Nusselt number. The results showed that the impact of quadratic thermal radiation on velocity and temperature distributions is more significant than linear thermal radiation. Further, an increase in quadratic convection and quadratic thermal radiation leads to an improvement in the friction coefficient of the skin on the inner surface of the outer annulus. Furthermore, the sensitivity of the friction coefficient is positive for the appearance of quadratic thermal radiation. 2020, SocietItaliana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature. -
Nonlinear Boussinesq buoyancy driven flow and radiative heat transport of magnetohybrid nanoliquid in an annulus: A statistical framework
The effect of nonlinear Boussinesq buoyancy force on the flow of Cu-Al2O3-H2O hybrid nanoliquid in a vertical annulus, which is adjacent to the radial magnetic field and thermal radiation, is analyzed through a statistical approach. The phenomena of movement of annuli are taken into account. The aspect of nonlinear density temperature is also accounted based on nonlinear Boussinesq approximation (NBA). The exact solution is obtained for the two-point boundary value problem comprised dimensionless governing equations. The skin friction coefficient and Nusselt number expressions are also estimated. The impacts of various physical parameters on the velocity, temperature, skin friction coefficient, and Nusselt number distributions are analyzed. The statistical techniques, such as correlation coefficient, probable error, and a multivariate regression model, are employed for the detailed analysis. It is found that the NBA is favorable for the skin friction coefficient and the rate of heat transfer. The maximum heat transfer is found on the wall of the internal annuli. 2020 Wiley Periodicals LLC -
Universal vortex statistics and stochastic geometry of Bose-Einstein condensation
The cooling of a Bose gas in finite time results in the formation of a Bose-Einstein condensate that is spontaneously proliferated with vortices. We propose that the vortex spatial statistics is described by a homogeneous Poisson point process (PPP) with a density dictated by the Kibble-Zurek mechanism (KZM). We validate this model using numerical simulations of the two-dimensional stochastic Gross-Pitaevskii equation (SGPE) for both a homogeneous and a hard-wall trapped condensate. The KZM scaling of the average vortex number with the cooling rate is established along with the universal character of the vortex number distribution. The spatial statistics between vortices is characterized by analyzing the two-point defect-defect correlation function, the corresponding spacing distributions, and the random tessellation of the vortex pattern using the Voronoi cell area statistics. Combining the PPP description with the KZM, we derive universal theoretical predictions for each of these quantities and find them in agreement with the SGPE simulations. Our results establish the universal character of the spatial statistics of point-like topological defects generated during a continuous phase transition and the associated stochastic geometry. 2024 authors. Published by the American Physical Society. -
Microstructural evolution and wear characteristics of equal channel angular pressing processed semi-solid-cast hypoeutectic aluminum alloys
This work investigated the microstructural evolution of Al-7Si-Mg alloy cast semi-solid using a cooling slope as well as conventional casting followed by equal channel angular pressing (ECAP) in a 120 die. Feed materials were prepared for ECAP by cooling slope casting and by conventional casting. The microstructure of the processed alloys extruded was observed by optical microscope and by transmission electron microscope, and their hardness and wear resistance were evaluated. After ECAP processing, the primary ?-Al phase tended to be elongated while the Si particles became fragmented and more nearly globular in shape and uniform in size than in the as-cast sample. The microstructure of the cooling slope-cast ECAPed samples was more homogenous than that of the conventionally cast ECAPed sample. The ?-Al phase sub-grains were refined to sub-micrometer sizes for samples cast by both methods after ECAP. The hardness of the cooling slope-cast ECAPed sample was also higher than that of the conventionally cast ECAPed sample. The wear resistance of the alloy improved after cooling slope casting and ECAP processing. 2014 The Authors. -
The effect of celebrity trustworthiness on endorsement effectiveness: A comparison of congruence and hybrid model /
Vision, Vol.23, Issue 3, pp.275-286 -
Effect of ethnocentrism and attitude towards foreign brands in purchase decision /
Vision, Vol.24, Issue 3, pp. 1-10 -
Quantum tunneling rotor as a sensitive atomistic probe of guests in a metal-organic framework
Quantum tunneling rotors in a zeolitic imidazolate framework ZIF-8 can provide insights into local gas adsorption sites and local dynamics of porous structure, which are inaccessible to standard physisorption or x-ray diffraction sensitive primarily to long-range order. Using in situ high-resolution inelastic neutron scattering at 3 K, we follow the evolution of methyl tunneling with respect to the number of dosed gas molecules. While nitrogen adsorption decreases the energy of the tunneling peak, and ultimately hinders it completely (0.33 meV to zero), argon substantially increases the energy to 0.42 meV. Ab initio calculations of the rotational barrier of ZIF-8 show an exception to the reported adsorption sites hierarchy, resulting in anomalous adsorption behavior and linker dynamics at subatmospheric pressure. The findings reveal quantum tunneling rotors in metal-organic frameworks as a sensitive atomistic probe of local physicochemical phenomena. 2023 authors. Published by the American Physical Society. -
Reflective thinking in school: a systematic review
Everything around us changes rapidly and to adapt to these constantly changing conditions and to understand the meaning of our life in the society in which we live, we must reflectively and consciously think about our actions in each given scenario. A school is a miniature form of society where learners are exposed to situations where they need to find solutions for every problem faced. No faultless solution and conclusions can be arrived at without a carefully employed reflective thinking process. In this context, the present study reviewed 19 intervention studies on reflective thinking in schools published between 2010 and 2021 and presents a brief summary. Various theories on reflective thinking, approach of educationists on reflective thinking of students and the relation between reflective thinking and students academic performance, are extensively analyzed. The findings of the study reveal that there are a few generally accepted theories of reflective thinking; reflection is a useful learning strategy and reflective thinking is an essential characteristic of academic excellence. This study recommends future research with a wider scope to accommodate more theoretical perspectives and wide-ranging databases. 2024, Institute of Advanced Engineering and Science. All rights reserved. -
Empowered learning in school: A scoping review
A high degree of motivation, a sense of commitment, self-efficacy and the ability to make the right choices are the characteristics of empowered learners. With education being seen as preparation for life, educators are increasingly pressured to develop curriculum and pedagogy that assist learners to become empowered. Based on the theoretical framework developed by Arksey and OMalley, the present study reviewed 16 empowered learning intervention studies at the school level published between the years 1995 and 2021 as well as provides an extensive summary of empowered learning enhancing interventions conducted in schools. This study highlights the concept of empowered learning, features and scope of interventions directed towards empowered learning of students at schools and the role of empowered learning in schools. Notwithstanding varied intervention results, the findings of this study indicate that empowered learning interventions produce highly motivated students with a sense of commitment and self-efficacy. This review also identifies the need for more pure experimental studies and a commonly accepted theory on empowered learning as a single concept. 2023, Institute of Advanced Engineering and Science. All rights reserved. -
An AI-enabled research support tool for the classification system of COVID-19
The outbreak of COVID-19, a little more than 2 years ago, drastically affected all segments of society throughout the world. While at one end, the microbiologists, virologists, and medical practitioners were trying to find the cure for the infection; the Governments were laying emphasis on precautionary measures like lockdowns to lower the spread of the virus. This pandemic is perhaps also the first one of its kind in history that has research articles in all possible areas as like: medicine, sociology, psychology, supply chain management, mathematical modeling, etc. A lot of work is still continuing in this area, which is very important also for better preparedness if such a situation arises in future. The objective of the present study is to build a research support tool that will help the researchers swiftly identify the relevant literature on a specific field or topic regarding COVID-19 through a hierarchical classification system. The three main tasks done during this study are data preparation, data annotation and text data classification through bi-directional long short-term memory (bi-LSTM). Copyright 2023 Tiwari, Bhattacharjee, Pant, Srivastava and Snasel. -
A framework for natural resource management with geospatial machine learning: a case study of the 2021 Almora forest fires
Background: Wildfires have a substantial impact on air quality and ecosystems by releasing greenhouse gases (GHGs), trace gases, and aerosols into the atmosphere. These wildfires produce both light-absorbing and merely scattering aerosols that can act as cloud condensation nuclei, altering cloud reflectivity, cloud lifetime, and precipitation frequency. Uttarakhand province in India experiences frequent wildfires that affect its protected ecosystems. Thus, a natural resource management system is needed in this region to assess the impact of wildfire hazards on land and atmosphere. We conducted an analysis of a severe fire event that occurred between January and April 2021 in the Kumaun region of Uttarakhand, by utilizing open-source geospatial data. Near-real-time satellite observations of pre- and post-fire conditions within the study area were used to detect changes in land and atmosphere. Supervised machine learning algorithm was also implemented to estimate burned above ground biomass (AGB) to monitor biomass stock. Results: The study found that 21.75% of the total burned area burned with moderate to high severity, resulting in a decreased Soil Adjusted Vegetation Index value (> 0.3), a reduced Normalized Differential Moisture Index value (> 0.4), and a lowered Normalized Differential Vegetation Index (> 0.5). The AGB estimate demonstrated a significant simple determination (r2 = 0.001702) and probability (P < 2.2 10?16), along with a positive correlation (r ? 0.24) with vegetation and soil indices. The algorithm predicted that 17.56 tonnes of biomass per hectare burned in the Kumaun forests. This fire incident resulted in increased emissions of carbon dioxide (CO2; ~ 0.8 10?4kgcarbonh?1), methane (CH4; ~ 200 10?9mol fraction in dry air), carbon monoxide (CO; 2000 1015moleculescm?2 total column), and formaldehyde (HCHO; 3500 1013moleculescm?2 total column), along with increased aerosol optical thickness (varying from 0.2 to 0.5). Conclusions: We believe that our proposed operational framework for managing natural resources and assessing the impact of natural hazards can be used to efficiently monitor near-real-time forest-fire-caused changes in land and atmosphere. This method makes use of openly accessible geospatial data that can be employed for several objectives, including monitoring carbon stocks, greenhouse gas emissions, criterion air pollution, and radiative forcing of the climate, among many others. Our proposed framework will assist policymakers and the scientific community in mitigating climate change problems and in developing adaptation policies. The Author(s) 2024. -
E-service quality-impact on customer satisfaction
The paper aims to determine the impact of e-service quality on customer satisfaction. The study utilised data from 252 customers of private and public banks in India through questionnaires. It was found that the e-service quality has significant impact on customer satisfaction in public sector banks as well as private sector banks. 2019 SERSC.