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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. -
Effects of reduced graphene oxide on nonlinear absorption and optical limiting properties of spin coated aluminium doped zinc oxide thin films
In this work, we investigate the nonlinear absorption and optical limiting properties of reduced graphene oxide (rGO) incorporated aluminum doped zinc oxide (AZO) composite thin films by open aperture z-scan technique using Q-switched Nd:YAG laser at 532 nm. The structural and spectral properties were also systemically analyzed. The composite thin films were synthesized by spin coating technique with online infrared curing facility. Studies on nonlinear optical responses of the investigated samples proved a substantial enhancement in the nonlinear absorption coefficient of AZO:rGO composites compared to AZO thin film. The nonlinear absorption is attributed to the two photon absorption with reverse saturable absorption. The strong nonlinear absorption and nonlinear scattering effects result in the optical limiting property of the composite material. The AZO:rGO thin film exhibits lower optical limiting threshold value (32 MW/cm2) as compared to AZO (59 MW/cm2). Hence it is an excellent optical limiter which explores applications in the field of optoelectronics as protecting material for sensitive photonic devices. 2021 -
Analysis and predictions of spread, recovery, and death caused by COVID-19 in India
The novel coronavirus outbreak was first reported in late December 2019 and more than 7 million people were infected with this disease and over 0.40 million worldwide lost their lives. The first case was diagnosed on 30 January 2020 in India and the figure crossed 0.24 million as of 6 June 2020. This paper presents a detailed study of recently developed forecasting models and predicts the number of confirmed, recovered, and death cases in India caused by COVID-19. The correlation coefficients and multiple linear regression applied for prediction and autocorrelation and autoregression have been used to improve the accuracy. The predicted number of cases shows a good agreement with 0.9992 R-squared score to the actual values. The finding suggests that lockdown and social distancing are two important factors that can help to suppress the increasing spread rate of COVID-19. 2018 Tsinghua University Press. -
Tunable graphene nanopatch antenna design for on-chip integrated terahertz detector arrays with potential application in cancer imaging
Aim: Further to our reports on chip-integrable uncooled terahertz microbolometer arrays, compatible with medium-scale semiconductor device fabrication processes, the possibility of the development of chip-integrable medical device is proposed here. Methods: The concept of graphene-based nanopatch antennas with design optimization by the finite element method (FEM) is explored. The high-frequency structure simulator (HFSS) utilized fine FEM solver for analyzing empirical mode decomposition preprocessing and for modeling and simulating graphene antennas. Results: Graphene nanopatch antennas exhibited tunable features with varying patch dimensions and dependence on substrate material permittivity. Conclusion: This work implements reconfigurable graphene nanopatch antenna compatible with terahertz microbolometer arrays. This design concept further develops on-chip medical devices for possible screening of cancer cell with terahertz image processing. 2021 Future Medicine Ltd. -
Real hypersurfaces of complex space forms satisfying FischerMarsden equation
Let M be a real hypersurface of a complex space form of constant curvature c. In this paper, we study the hypersurface M which admits a nontrivial solution to FischerMarsden equation, that is, the induce metric g of M satisfies Hessg(?) = (?g?) g+ ?Sg, where ? is a nontrivial function. We prove that there does not exist a complete Hopf real hypersurface in a non-flat complex space form satisfying FischerMarsden equation. Finally, we show that a complete real hypersurface with A?= ??, ?? 0 , of a complex Euclidean space Cn satisfying FischerMarsden equation is locally congruent to a sphere or S1R2n-2. 2021, Universitdegli Studi di Ferrara. -
Heavy metal stress influence the andrographolide content, phytochemicals and antioxidant activity of Andrographis paniculata
Heavy metals (HM) are toxic components present in the earth's crust that can have a negative impact on plants as well as animals. Andrographis paniculata or 'King of bitters' belonging to the family Acanthaceae, is a medicinal herb traditionally used in the treatment of fever, common cold etc. In the present study, the effect of heavy metals (copper, tin and cobalt) on the andrographolide content, biochemical parameters like chlorophyll, carotenoid, protein, Total phenolic content (TPC), Total flavonoid content (TFC) and antioxidant activity in A. paniculata were analysed. Saplings of A. paniculata were treated at 50 and 100 mM concentrations, three different times at a time interval of 7 days. Andrographolide production was found to increase in copper and cobalt treated saplings when compared with the control. From the results, maximum andrographolide concentration was found in the saplings treated with 50 mM copper (8.51 mg/gm of DW) and 50 mM tin (8.10 mg/gm of DW) respectively. 50 mM cobalt treated plants have shown the highest concentration of TPC (17.21 mg/g of extract) and TFC (6.97 mg/gm of extract). Notable variations in other biochemical parameters like total chlorophyll, carotenoid content and antioxidant activities were observed in all treatments compared with the control. Antony & Nagella (2021). This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited (https://creativecommons.org/licenses/by/4.0/). -
Smartphone based indoor localization and tracking model using bat algorithm and Kalman filter
In recent days, accurate localization becomes essential for enabling smartphone-based navigation to attain maximum accuracy in the construction of the real world.Fingerprint-based localization is the widespread solution to achieve and assure effective performance. In this study, a new fingerprint-based localization model using a bat algorithm (BA) is presented stimulated by the echolocation nature of microbats. The presented model adapts BA for estimating the location information. Initially, the presented model applies a Bayesian-rule based objective function. Then, the BA is used for improving the accuracy and analyzing the effects of the initial position of the bats on the localization outcome. For mitigating the estimation error, the Kalman filter is employed for updating the initially determined position using the BA for tracking purposes. The experimental analysis indicated an improvement in real-time performance and decrease in computation complexity. The presented model also obtained maximum localization accuracy with minimum localization error over the compared methods. 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature. -
Significance of nonlinear Boussinesq approximation and non-uniform heat source/sink on nanoliquid flow with convective heat condition: sensitivity analysis
The quadratic convective flow of nanoliquid over an elongating plate subjected to non-uniform heat source/sink, partial slip, and Newton boundary conditions is studied by using the modified Buongiorno model. The correlation for effective thermal conductivity and viscosity of nanoliquid are taken from the experimental work of Corcione. The dimensionless velocity, temperature, rate of heat transport, and mass transport distributions are simulated by solving the nonlinear boundary value problem using the finite difference method. The additional novelty of the present study is an application of response surface methodology to scrutinize the interactive impact of key parameters on the rate of heat transfer. Further, the influence of key parameters is deliberated on various flow fields using the surface and streamline plots. The higher velocities are noticed for the case of nonlinear Boussinesq approximation as compared with the usual Boussinesq approximation. The temperature enhances with a non-uniform heat source/sink aspect. The sensitivity of the heat transfer to the nanoparticle volume fraction remains positive. 2021, The Author(s), under exclusive licence to SocietItaliana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature. -
Diagnosis and prediction of iigps countries bubble crashes during brexit
We herein employ an alternative approach to model the financial bubbles prior to crashes and fit a log-periodic power law (LPPL) to IIGPS countries (Italy, Ireland, Greece, Portugal, and Spain) during Brexit. These countries represent the five financially troubled economies of the Eurozone that have suffered the most during the Brexit referendum. It was found that all 77 crashes across the five IIGPS nations from 19 January 2015 until 17 February 2020 strictly followed a log-periodic power law or other LPPL signature. They all had a speculative bubble phase (following the power law growth) that was then followed by a sudden crash immediately after reaching a critical point. Furthermore, their pattern coefficients were similar as well. This study would surely assist policymakers around the Eurozone to predict future crashes with the help of these parameters. 2021 by the authors. Licensee MDPI, Basel, Switzerland. -
Estimation of the size and structure of the broad line region using Bayesian approach
Understanding the geometry and kinematics of the broad line region (BLR) of active galactic nuclei (AGN) is important to estimate black hole masses in AGN and study the accretion process. The technique of reverberation mapping (RM) has provided estimates of BLR size for more than 100 AGN now; however, the structure of the BLR has been studied for only a handful number of objects. Towards this, we investigated the geometry of the BLR for a large sample of 57 AGN using archival RM data. We performed systematic modelling of the continuum and emission line light curves using a Markov chain Monte Carlo method based on Bayesian statistics implemented in PBMAP (Parallel Bayesian code for reverberation-MAPping data) code to constrain BLR geometrical parameters and recover velocity integrated transfer function. We found that the recovered transfer functions have various shapes such as single-peaked, double-peaked, and top-hat suggesting that AGN have very different BLR geometries. Our model lags are in general consistent with that estimated using the conventional cross-correlation methods. The BLR sizes obtained from our modelling approach is related to the luminosity with a slope of 0.583 0.026 and 0.471 0.084 based on H ? and H ? lines, respectively. We found a non-linear response of emission line fluxes to the ionizing optical continuum for 93 per cent objects. The estimated virial factors for the AGN studied in this work range from 0.79 to 4.94 having a mean at 1.78 1.77 consistent with the values found in the literature. 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. -
Impact of lockdown during COVID-19 pandemic on the learning status of undergraduate and postgraduate students of Bangalore
Background: The COVID 19 pandemic has created various impacts on every human's life. COVID 19 lockdown has provoked enormous changes in the education sector which in turn influences the student's life in many aspects. The scope of this study is to understand the impact in both undergraduate and postgraduate students. Aim: This study aims at incisively analyzing the impact of lockdown imposed due to the COVID-19 pandemic on graduate students of Bangalore. Method: It is an online survey that encompasses a structural questionnaire with open-ended questions created using Google Forms, which were sent across the students through social media platforms. Results: A total of 115 students from both undergraduate and postgraduate programs have participated in this survey. Simple percentage distribution was estimated to evaluate the pedagogy, opinion on educational decisions, modes of learning, socio-economic conditions, and problems pertaining to academia because of this pandemic. As per this analysis, 80.9% of students faced difficulty due to lockdown. 67% of students thought that their family's income will be affected by this pandemic. 68.7% of students felt stressed, depressed and 52.3% of students could not find a suitable environment in their home to study during this lockdown. When we see this pandemic in an optimistic light, it has created various opportunities such as Digital learning and adoption of new health habits. 2021. RIGEO. All Rights Reserved. -
Solution for Fractional KuramotoSivashinsky Equation Using Novel Computational Technique
In this paper, we analyse the nonlinear model describing the different physical and chemical phenomena, namely KuramotoSivashinsky equation. For the fractional KS (FKS) equation the approximated analytical solution is obtained with the help of the q-homotopy analysis transform method (q-HATM). The projected technique is a mixture of Laplace transform and homotopy analysis method. The considered technique offers ?-curves that show convergence range of the obtained series solution. To confirm the efficiency and applicability of the projected scheme, we consider four distinct examples. The numerical study is conducted to authorize the accuracy and reliability of the considered method. Further, natures of the achieved results have been presented for different order. The obtained solution illuminates that, the projected algorithm is very effective and easy to implement to examine the behaviour nonlinear models exist in science and technology. 2021, The Author(s), under exclusive licence to Springer Nature India Private Limited part of Springer Nature. -
Facile Synthesis of Few-Layer Graphene Oxide from Cinnamomum camphora
Abstract: This study presents a facile synthesis technique to produce few-layer graphene oxide from Cinnamomum camphora (Camphor L.). Camphor upon carbonization and chemical oxidation leads to the formation of few-layer graphene oxide sheets of around ten layers with a lateral size of 4.14 nm and stacking height of 3.10 nm. AFM and SEM analysis results reveal the wrinkled morphology of the graphene oxide sheets formed. The sharp G band and the relative intensity of the defect to the graphitic band in the Raman spectrum indicate the formation of nanocrystalline graphene oxide sheets with fewer defects. The FTIR spectrum and the deconvoluted C 1s XPS spectrum of graphene oxide synthesized reveal the presence of predominant sp2 hybridized carbon along with carbon bound to various oxygen functionalities. In brief, the formation of high-quality few-layer graphene oxide from an abundant, low-cost, and readily available botanical precursor is herein reported. 2021, Pleiades Publishing, Ltd. -
Aza-Michael addition of 1,2-diazoles to structurally diverse enones: Efficient methods toward ?-amino ketones
An efficient and mild protocol was realized using 1,2-diazoles and related heterocycles with cyclic and acyclic enones in presence of T3P (2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphorinane-2,4,6-trioxide) toward the regioselective formation of N-cycloalkyl heterocycles at room temperature. The developed reaction conditions showcased good selectivity over a wide range of 1,2-diazoles and enones by delivering N-cycloalkyl heterocycles in excellent yields. 2020 Wiley Periodicals LLC. -
Customers response to online food delivery services during COVID-19 outbreak using binary logistic regression
This study aims to empirically measure the distinctive characteristics of customers who did and did not order food through Online Food Delivery services (OFDs) during the COVID-19 outbreak in India. Data are collected from 462 OFDs customers. Binary logistic regression is used to examine the respondents characteristics, such as age, patronage frequency before the lockdown, affective and instrumental beliefs, product involvement and the perceived threat, to examine the significant differences between the two categories of OFDs customers. The binary logistic regression concludes that respondents exhibiting high-perceived threat, less product involvement, less perceived benefit on OFDs and less frequency of online food orders are less likely to order food through OFDs. This study provides specific guidelines to create crisis management strategies. 2020 John Wiley & Sons Ltd -
Corrosion mitigation performance of disodium EDTA functionalized chitosan biomacromolecule - Experimental and theoretical approach
Disodium ethylenediaminetetraacetate salt is known for its excellent coordinating properties with the metal ions. The present study deals with the investigation of the prepared Disodium EDTA functionalized chitosan in corrosion inhibition for mild steel in 1 M HCl. The modified chitosan was characterized by spectral studies, thermal analysis, and Zeta potential studies. The corrosion inhibition efficiency (%) was evaluated using the gravimetric method and electrochemical studies. The electrochemical studies included potentiodynamic polarization, linear polarization resistance, and electrochemical impedance methods. The modified chitosan polymer showed an inhibition efficiency of 96.63% for 500 ppm at 303 K. Adsorption process obeyed Langmuir isotherm. Experimental results and theoretical calculations endorsed initial physisorption followed by a chemisorption process. Surface characterization studies supported the formation of a protective film that enabled the inhibition process. Density functional theory, Monte Carlo studies, and molecular dynamics simulation studies show a good agreement with the experimental results. Two-way Analysis of Variance was performed to test the influence of immersion period and inhibitor concentration on the corrosion rate using the statistical software IBM SPSS 20.0. A quartic model was generated as the best fit with the highest R2 value of 0.973. Design Expert software was employed for statistical modeling fit. 2021 -
The effect of servant leadership on ad hoc schoolteachers affective commitment and psychological well-being: The mediating role of psychological capital
Progress on the fourth United Nations Sustainable Development Goal (SDG4), which strives to ensure inclusive and equitable quality education, can only be made with teachers whose levels of job satisfaction and dedication to teaching are high. The authors of this article conducted a survey among ad hoc teachers (also referred to as para teachers) in rural India. The purpose of their study was to find out the extent to which being led by principals who practised a management style termed servant leadership positively impacted respondents affective commitment and psychological well-being. A servant leader seeks to serve by developing the followers selfhood in various relational, ethical, emotional and spiritual contexts. This has the effect of encouraging the followers to become the best version of themselves. Data collection involved the completion of a questionnaire by a sample of 1,120 (840 female, 280 male) para teachers from 17 non-formal community learning centres and 10 schools in the Indian state of Jharkhand. The results of the survey revealed that there is an indirect effect of servant leadership on affective commitment and psychological well-being through a set of three elements, hope, efficacy and resilience, which together amount to a para teachers personal resource of psychological capital. Relying on the findings of their research, the authors suggest that it will be beneficial for Jharkhands Department of Education to implement interventional teacher training programmes which nurture servant leadership among school principals and educational officers and thereby foster psychological capital among para teachers. 2020, UNESCO Institute for Lifelong Learning and Springer Nature B.V. -
Statistical features from frame aggregation and differences for human gait recognition
Human gait recognition, an alternate biometric technique, received significant attention in the last decade. As many gait recognition applications require real-time response, the primary concern is to design efficient and straightforward gait features for human recognition. In this work, two novel gait features are proposed. Both features are designed by exploring the dynamic variations of different body parts during a gait cycle. The first feature set is based on one-against-all gait frame differences for person identification. This novel approach divides each frame in a gait cycle to blocks, compute the block sum, and then find the difference of respective block sum between the first frame and the rest. The second feature set is defined on the first-order statistics of the normalized sum of the frames in a cycle. Two other existing features- Centroid of Silhouette frames and feature values defined on Change Energy Images are also considered. Feature level fusion is realized by considering the different combinations of the four types of features. Experiments carried out with the CASIA Gait Dataset B demonstrated the proposals merit with high recognition accuracy. The outcome of the investigations is promising when compared to recent contributions. 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature. -
Significance of exponential space-based heat source and inclined magnetic field on heat transfer of hybrid nanoliquid with homogeneousheterogeneous chemical reactions
Many chemical reactive methods, like combustion, catalysis, and biochemical involve homogeneousheterogeneous chemical reaction(HHCR). The collaboration amongthe heterogeneous and homogeneous reactions is exceedingly multifarious, including the creation and depletion both within the liquid and catalytic surfaces. Here, we observe the influences of Cuand Al2O3nanoparticles past an elongating sheet under HHCR. An inclined magnetic field with an acute angle is applied to the direction of the flow. Further, radiative heat, temperature, and exponential space-based heat source aspects are modifying the thermal equation. The governing nonlinear equations are deciphered by utilizing the RungeKutta-based shooting method. It is found that HHCRreduces the solute layer thickness, whereas the increase in the angle of inclination of applied magnetism thickens momentum layer thickness. 2021 Wiley Periodicals LLC -
Study on academics and stress during Covid-19 outbreak
The objectives of the study were to identify and analyze the leading causes of academic stress that may have significant effects on the success and well-being of students and explore the significant sources of stress among students during their studies during the COVID-19 outbreak. The study was also conducted to understand if their gender-wise differences on the basis of academic stress reported. The sample consisted of 100 students and 15 sources of stress divided into three categories: relations with other people, personal factors, and academic factors. results show the academic sources of stress appeared to be the most stressful for all the students due to the pressure originated from the course overloads and the academic evaluation procedures. The findings from this study may be useful for further research on how these potential sources of stress influence the performance and the health of the students. 2021 Ecological Society of India. All rights reserved.