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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. -
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. -
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 -
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. -
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. -
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 -
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. -
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 -
Antifouling Nanoparticle Coatings for Post-Harvest Food Preservation
The reports of the World Food Preservation Center exhibit that the entire number of inhabitants in the globe will reach 9.6 billion by the year 2050. With the increasing population, there is a growing pressure on agricultural produce which is further amplified by the losses between harvest and retail (~17%) and other wastages (~17%). Globally, this is a major concern, and thus, there is no surprise to look into current research developments in food preservation. This chapter provides comprehensive reports on the recent trends in various nanoparticle coatings for the aforementioned application. Silicon dioxide (SiO2), titanium dioxide (TiO2), and zinc oxide (ZnO) nano regime coatings on silicon substrate and polymer substrates have been discussed for antifouling applications. This chapter is categorized as follows: Section I delivers the introduction about the significance of food preservation in reference to the reported statistics. In section II, the discussion starts with the materials and methods for post-harvest food saving. Major recent advances in terms of materials or methods to increase the shelf life of cuisine are portrayed in the same section II. Section III entails the appropriate computational methods to envision the interaction of food residuals with coated nanolayers through sensing. The final section (IV) delivers a guideline on feasible research implications to address the shortcomings in food preservation from a broader perspective. 2024 Scrivener Publishing LLC. -
Advancement and Challenges of Biosensing Using Field Effect Transistors
Field-effect transistors (FETs) have become eminent electronic devices for biosensing applications owing to their high sensitivity, faster response and availability of advanced fabrication techniques for their production. The device physics of this sensor is now well understood due to the emergence of several numerical modelling and simulation papers over the years. The pace of advancement along with the knowhow of theoretical concepts proved to be highly effective in detecting deadly pathogens, especially the SARS-CoV-2 spike protein of the coronavirus with the onset of the (coronavirus disease of 2019) COVID-19 pandemic. However, the advancement in the sensing system is also accompanied by various hurdles that degrade the performance. In this review, we have explored all these challenges and how these are tackled with innovative approaches, techniques and device modifications that have also raised the detection sensitivity and specificity. The functional materials of the device are also structurally modified towards improving the surface area and minimizing power dissipation for developing miniaturized microarrays applicable in ultra large scale integration (ULSI) technology. Several theoretical models and simulations have also been carried out in this domain which have given a deeper insight on the electron transport mechanism in these devices and provided the direction for optimizing performance. 2022 by the authors. -
An efficient cloud based architecture for integrating content management systems
The use of digital content is increasing day after day and now it is an essential element of our day today life. The amount of stored information is so huge that it is highly difficult to manage the content especially in a distributed cloud environment. There are many open source software solutions available in cloud to handle huge amount of digital data. However none of these solutions addresses all the requirements needed to manage the content spread out in multiple systems effectively. The user has to relay on multiple content management systems to do the work. This turns into ever more unwieldy, time consuming and leads to loss of data. Using robust and integrated content management systems, these issues could be solved effectively. In this paper we have identified various challenges of using the content management system in the cloud after surveying many Content Management System related article and proposed an integrated solution named Cloud based Architecture integrating Content Management System which is capable of interfacing with various unique features available at different content management system installations in the cloud. This maximizes the functionality and performance of any Content management systems. The Representational State Transfer (REST) protocol is used to integrate the best features of various open source content management systems. REST provides higher level of security compared to existing systems as it does not store the user sessions. The users can interact with the system with the help of an interface which abstracts the complexities of multiple content management systems running in the cloud. 2017 IEEE. -
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. -
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) -
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. -
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. -
Impact of Improved Corporate Governance and Regulations on Earnings Management PracticesAnalysis of 7 Industries from the Indian National Stock Exchange
This study investigates discretionary earnings management practices, tracing the changes over the years in selected top performing and highly liquid listed Indian firms. It empirically measures the impact of corporate governance, financial legislation and global reporting standards on the firms earnings management practices. The study analyses a sample of 712 firm-year data comprising 89 listed Indian companies across 7 different sectoral indices of the National Stock Exchange of India (NSE) over 8 years (20112018). The Modified Jones model was used to compute Discretionary Accruals to measure Earnings Management based on data obtained using Bloomberg terminals. Statistical results and plots generated in Stata offer evidence that instances of earnings management have significantly reduced after the enactment of the Companies Act 2013 and the adoption of Indian Accounting standards which are converged with the IFRS. Findings suggest that services firms are engaging in relatively higher levels of earnings management compared to manufacturing firms. This study reveals the positive impact of improved corporate governance, regulation, and enforcement by significantly reducing the levels of earnings management among listed firms in India. 2021 by the authors. -
IMPACT OF ARTIFICIAL INTELLIGENCE ON E-BANKING AND FINANCIAL TECHNOLOGY DEVELOPMENT
Artificial intelligence has a significant impact on financial technologies. Machine learning is an important field of artificial intelligence. Machine learning is a subset of artificial intelligence. According to client knowledge gathered by machine learning, data structures may be more easily comprehended and changed. Machine learning, although still being employed in the IT business, has its own set of benefits. They are used by computer program to explain or solve a typical issue because they are a set of well-written instructions. Data inputs for factual research may be prepared by computers using master learning algorithms that can deliver results within a certain range. Computers are used to model test data, and frameworks are used to make automated decisions based on input data. Banks and financial institutions may benefit from the use of machine learning. This article discusses applications of machine learning in banking and finance sector. The Electrochemical Society -
Identification and standardization of counsellor competencies for master level counsellor education programs in india
Counselling psychology programs in India have been criticized for being poor replicas of newlineconcepts that have originated in western cultures . The lack of Indian models has been quoted as a drawback indicating that trainees are not necessarily competent to provide effective counselling services. The present study aimed at identifying and standardizing competencies for post graduate counsellor training in India based on local needs.The study employed a mixed methods design with four phases. In the first phase, a list of key occupational tasks were drawn up through a systematic review of literature and interviews with three expert practitioners. The second phase was the development of a counsellor competency list which outlined the various competencies required to fulfil the key occupational tasks determined in the previous stage. Seventy one competencies were identified and the list was then given for newlineexpert validation. In the third phase, the competency list was given to 75 practicing newlinecounsellors across India who rated the competencies on a 5-point likert scale, based on its importance for post graduate counsellor trainees. In the final stage the prioritized competencies were analyzed using a concept development approach to identify core competencies required for master level counselling psychology trainees. The resulting core competencies were three foundational competency domains which included ethical practice, personal and professional development and cultural sensitivity. There were also three newlinefunctional competency domains which included the counselling process, the supervision newlineprocess and the promotion of counselling in India. Specific competencies under each domain were also listed along with behavioral indicators for the same. Thus the core competencies that counsellor trainees must develop to provide an effective service were identified and this has implications for training and practice. -
Facile Fabrication of Nano carbon Derivatives for Optical and Electro chemical Applications
From synthesis of novel materials to their end-use applications, the prime objective of the material science community is to address the burgeoning social issues across the world. Noxious emissions from fossil fuel combustion, increased incidence of skin cancer, drug misuse, and ever-increasing demand for energy are some of the global concerns that require urgent consideration. This drives a relentless quest for a multifunctional material with broad applicability that can directly and constructively impact the quality of life, environment, and economic progress. However, materials of this kind should embrace versatile characteristics, improved competency, plausibility, and lower cost. In light of this, the current doctoral research emphasizes the development of trailblazing graphene-based materials with manifold usages derived from a naturally abundant carbonaceous fossil fuel coke to discover scientific solutions to the aforesaid trials and tribulations. Fossil fuel coal, mainly used for energy purposes, is often discouraged from industrial and domestic consumption due to its contribution to global warming. Despite the fact that coal is a non-renewable resource and a source of greenhouse gas emissions, it is one of the world's bountiful carbon resources. Therefore, it can be exploited as a potent substitute for conventional graphite, enabling the extraction of value-added graphene derivatives along with the sustainable utilization of coal. However, the purity of the precursor is a vital criterion to guarantee the quality and supply of graphene materials. In this doctoral work, coal-coke with 99% carbon content was used for the production of high-quality oxidized multilayer graphene derivatives by employing an environmentally-benign synthesis technique. The obtained graphene structure exhibited a multi-emissive fluorescence property having emissions ranging from blue to green-yellow. In addition, it also possessed remarkable electrochemical performance, good rate capability, and durability, signifying its expediency in energy storage devices. In an attempt to further enhance the scope of as-synthesized coke-based graphene derivatives, heteroatoms such as nitrogen and phosphorus were introduced into the graphene lattice via substitutional doping. It was perceived that nitrogen doping impressively amended the photophysical properties, especially in terms of quantum yield and fluorescence lifetime. Therefore, the as-synthesized nitrogen-doped multilayer graphene derivative was used as a fluorescent biomarker for imaging melanoma skin cancer cells with the purpose of early detection. Wherein co-doping of nitrogen and phosphorus endorsed excellent electrochemical characteristics and sensing performance, owing to the synergistic effect from heteroatoms and the imparted structural corrugations. Thus, by utilizing the as-synthesized nitrogen, phosphorus co- doped heteroatom derivative, oxytocin, a high-risk abused drug, was electrochemically detected in an nM range and validated the possibility of real-time surveillance over its mishandling in edibles and biological models. The coke-based graphene derivatives were further refashioned to obtain optimum textural and surface chemistry characteristics beneficial for energy storage characteristics. Accordingly, simultaneous heteroatom-doping and activation of graphene derivative were achieved. The obtained sample had a high surface area, hierarchical porous structure, increased defect densities, and co-active heteroatom enriched graphene network, suggesting its potential as an electrode material for supercapacitor applications. It was observed that the as-synthesized simultaneously heteroatom-doped and activated samples demonstrated high capacitance value, appreciable cyclic stability, and lower charge-transfer resistance. Henceforth, such enhanced supercapacitive performance points toward the cradle-to-gate transformation of fossil fuel, i.e., the conversion of sluggish black coal to green energy. -
Linear and nonlinear convection in magnetic fluids /
The thesis deals with linear and nonlinear Rayleigh-Benard ferroconvection in a horizontal porous layer. Modified Darcy law is used to describe the fluid motion. The effect of chemical reaction, temperature modulation, gravity modulation and finite amplitudes on the onset of Darcy ferroconvection is considerd. The findings of the problems addressed in the thesis may come in handy for heat transfer application situations with ferromagnetic fluids as working medium.