A Numerical Investigation on Thermal Gradients and Stresses in High Temperature PEM Fuel Cell During Start-up
Finite element analysis; Fluid-structure interaction; Fuel cell; Start-up; Thermal stress
The High Temperature Polymer Electrolyte Fuel Cell (HT-PEMFC) stacks using polybenzimidazole (PBI) based membranes have an inability to internally heat up at low temperatures to their nominal operating temperature (160C180C) during the start-up process. Several strategies, such as direct electrical heating, coolant/gas channel heating, catalytic hydrogen-oxygen combustion, etc., are proposed in the literature to assist the heating for quick start-up situations. However, little knowledge exists on the transient thermomechanical stresses induced during the start-up heating process due to non-uniformity in heat supply and disparity in thermal properties of the cell components. The objective of the present research is to analyze the thermal gradients and thermal stresses developed in the HT-PEMFC structure during the start-up with various heating methods discussed in the literature, as well as during the cell operation by exploiting the Fluid-Structure Interaction (FSI) approach. The use of polyalkylene glycol (Fragoltherm S-15-A) based Heat Transfer Fluid (HTF) in the coolant channel has substantially improved the start-up time due to the high Nusselt number. However, a significant gradient in temperature distribution is observed during the preheating process, which resulted in great inhomogeneous stresses in the membrane, particularly in the in-plane direction. Interestingly, the degree of uniformity in membrane current density distribution during cell operation is increased. A detailed heat analysis in the cell showed that the heat generated in the cell due to electrochemical reactions is sufficient to raise the cell temperature from 120C to operating temperature in a short time. Being subjected to a compressive stress of above 40 MPa, which is higher than the ultimate strength of a typical acid doped PBI membrane, the electrolyte is the most vulnerable component during the start-up. Hence, to inhibit the concomitant effect on cell performance and degradation, a novel start-up strategy should be implemented. 2021 Elsevier Ltd
Varghese G.; Babu?K.P. V.; Joseph T.V.; Chippar P.
International Journal of Heat and Mass Transfer, Vol-175
https://doi.org/10.1016/j.ijheatmasstransfer.2021.121365 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105331960&doi=10.1016%2fj.ijheatmasstransfer.2021.121365&partnerID=40&md5=8685eb6ed9564cc310e26e2d24b8c149
Varghese G., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Babu?K.P. V., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Joseph T.V., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Chippar P., St Joseph Engineering College (Affiliated to Visvesvaraya Technological University, Belagavi), VamanjoorMangaluru, 575 028, India
Combined effect of channel to rib width ratio and gas diffusion layer deformation on high temperature Polymer electrolyte membrane fuel cell performance
Clamping pressure; Contact resistance; Fuel cell; GDL deformation; Numerical modeling
The present study investigates the combined influence of Channel to Rib Width (CRW) ratio and clamping pressure on the structure and performance of High Temperature-Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) using a three-dimensional numerical model developed previously. It also considers the impact of interfacial contact resistance between the Gas Diffusion Layer (GDL) and Bipolar Plate (BPP). The structural analysis of the single straight channel HT-PEMFC geometry shows that the von-Mises stress greatly increases in the GDL under the ribs as the CRW ratio increases resulting in considerably high deformation. The cell performance analysis depicts the significance of ohmic resistance and concentration polarization for different CRW ratios, particularly at higher operating current densities. However, in low to medium current density regions, the CRW ratio has little influence on cell performance. A substantial impact on the species, overpotential, and current distributions is observed. The findings also reveal that the CRW ratio significantly affects the temperature distribution in the cell. 2022 Hydrogen Energy Publications LLC
Varghese G.; K. P V.B.; Joseph T.V.; Chippar P.
International Journal of Hydrogen Energy, Vol-47, No. 77, pp. 33014-33026.
https://doi.org/10.1016/j.ijhydene.2022.07.178 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85135927882&doi=10.1016%2fj.ijhydene.2022.07.178&partnerID=40&md5=7db548504bf22094352ce721bf4c9b7b
Varghese G., CHRIST (Deemed to be University), Bengaluru, 560 029, India; K. P V.B., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Joseph T.V., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Chippar P., Applied Engineering and Computational Analysis Laboratory, St Joseph Engineering College (Affiliated to Visvesvaraya Technological University, Belagavi), Vamanjoor, Mangaluru, 575 028, India
Effect of Coupled Microstructural Characteristics of Catalyst Layer on High Temperature: Proton Exchange Membrane Fuel Cell Performance
The widespread adoption of High Temperature-Proton Exchange Membrane Fuel Cells (HT-PEMFC) in commercial applications is limited by their performance and durability compared to conventional energy sources. A key factor affecting these cells is the sluggish oxygen reduction reaction (ORR) at the cathode catalyst layer (CL). Optimizing the structural parameters of the cathode CL can enhance cell performance and longevity. Current research on these parameters is mostly descriptive, lacking numerical evidence to quantify their impact. This study develops a three-dimensional, non-isothermal HT-PEMFC numerical model to investigate the sensitivities of coupled structural parameters of the cathode CL, including Pt loading, CL thickness, and Pt particle diameter, at three levels. The orthogonal/Taguchi approach quantitatively assesses the impact of these parameters. The study reveals that Pt loading significantly affects cell voltage and cathode overpotential, while Pt diameter influences the homogeneity of overpotential distribution. The dominant impact of a single parameter decreases at higher current densities, necessitating careful analysis of trade-offs between different structural characteristics to maximize performance. These findings offer valuable insights for future experimental studies to enhance cell performance through adjustments to cathode catalyst characteristics. 2024 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Varghese G.; Venkatesh Babu K.P.; Joseph T.V.; Chippar P.
Journal of the Electrochemical Society, Vol-171, No. 10
https://doi.org/10.1149/1945-7111/ad86ee https://www.scopus.com/inward/record.uri?eid=2-s2.0-85208280205&doi=10.1149%2f1945-7111%2fad86ee&partnerID=40&md5=e67c80d11b36cbbcc6a5937d5b377e6d
Varghese G., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Venkatesh Babu K.P., Applied Engineering and Computational Analysis Laboratory, St Joseph Engineering College (Affiliated to Visvesvaraya Technological University, Belagavi), Vamanjoor, Mangaluru, 575 028, India; Joseph T.V., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Chippar P., Applied Engineering and Computational Analysis Laboratory, St Joseph Engineering College (Affiliated to Visvesvaraya Technological University, Belagavi), Vamanjoor, Mangaluru, 575 028, India
Impacts of Pore Scale Gas Diffusion Layer Deformation on PEMFC Performance at Sub Zero Operation
Highlights Impact of assembly pressure on species and charge transport during cold start operation. Inhomogeneous GDL compression and intrusion is considered in the study. The intrusion effect leads to intense ice accumulation under the channels at 2 MPa. The importance of applying appropriate clamping pressure is highlighted in the study. 2023 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited
Journal of the Electrochemical Society, Vol-170, No. 11
https://doi.org/10.1149/1945-7111/ad08ee https://www.scopus.com/inward/record.uri?eid=2-s2.0-85177484240&doi=10.1149%2f1945-7111%2fad08ee&partnerID=40&md5=dbba2529f799da3dffd420e595310eca
Varghese G., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Venkatesh Babu K.P., Applied Engineering and Computational Analysis Laboratory, St Joseph Engineering College, Affiliated to Visvesvaraya Technological University, Belagavi), Mangaluru, 575 028, India; Joseph T.V., CHRIST (Deemed to be University), Bengaluru, 560 029, India; Chippar P., Applied Engineering and Computational Analysis Laboratory, St Joseph Engineering College, Affiliated to Visvesvaraya Technological University, Belagavi), Mangaluru, 575 028, India
Cryptocurrency Security and Privacy Issues: A Research Perspective
Bitcoin; Blockchain; cryptocurrency; Ethereum; Gold; Privacy; Security
Cryptocurrency has developed as a new mode of money exchange since it has become easier, faster and safer. The first cryptocurrency was introduced in 2009 and since then, the growth rate of cryptocurrency has been increasing drastically. As of 2020, the cryptocurrency exchange all over the world has exceeded 300%. The researchers face many challenges during their research on the various cryptocurrencies. For example, most of the high-tech companies still do not support bitcoin on mobile platforms. High-tech companies like Google and Apple are also thinking into banning the bitcoin wallet from their app stores. The work provides a review of cryptocurrency and its types, scope on the investment plans and its advantages also discussed. The growth and comparison between bitcoins and gold is also discussed. The challenges researchers face and the security issues concerning it. This review provides an overview of how the different forms of cryptocurrency are increasing from over a decade. It explains the different types and the year in which they were invented. It also gives a brief comparison with respect to bitcoin, which is one of the most used cryptocurrency. Furthermore, it gives a brief explanation on investments, and schemes for those who are new in the cryptomarket. Later emphasizes on the security issues faced by this technology. It talks about proof of work and the different data attacks the software faced and how the issues were overcome. In the end, it talks about the challenges researchers face while researching cryptocurrency. 2021 IEEE.
Varghese H.M.; Nagoree D.A.; Anshu; Jayapandian N.
Proceedings of the 6th International Conference on Communication and Electronics Systems, ICCES 2021, pp. 902-907.
Institute of Electrical and Electronics Engineers Inc.
Varghese H.M., Christ University, Department of Cse, Bangalore, India; Nagoree D.A., Christ University, Department of Cse, Bangalore, India; Anshu, Christ University, Department of Cse, Bangalore, India; Jayapandian N., Christ University, Department of Cse, Bangalore, India
Review on Segmentation of Facial Bone Surface from Craniofacial CT Images
Computed tomography; Craniofacial image analysis; Deep learning; Machine learning; Mandible segmentation; Orthognathic surgery; Segmentation
Three-dimensional (3D) representation of facial bone surface is needed in the virtual surgical planning for orthognathic surgery. Segmentation of facial bone surface from computed tomography images is first step in developing the 3D model. With the advent in the computer vision techniques, various automatic and semi-segmentation algorithms were developed in the recent years for segmentation of facial bone surface from craniofacial computed tomography images. In the proposed paper, the various segmentation techniques for extracting bone surface from 3D CT images for corrective jaw surgery available in the literature have been discussed. By reviewing all the methods available in the literature, it is found that each method has its own merits and demerits. 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Lecture Notes on Data Engineering and Communications Technologies, Vol-117, pp. 717-738.
Springer Science and Business Media Deutschland GmbH
Varghese J., Department of Computer Science, Christ Deemed To Be University, Karnataka, Bangalore, India, Christ Academy Institute for Advanced Studies, Karnataka, Bangalore, India; Saleema J.S., Department of Computer Science, Christ Deemed To Be University, Karnataka, Bangalore, India
Machine Learning Techniques for Automated Nuclear Atypia Detection in Histopathology Images: A Review
Breast cancer; Deep learning; Histopathological image; Machine learning; Nuclear atypia detection; Nuclear pleomorphism
Nuclear atypia identification is an important stage in pathology procedures for breast cancer diagnosis and prognosis. The introduction of image processing techniques to automate nuclear atypia identification has made the very tedious, error-prone, and time-consuming procedure of manually observing stained histopathological slides much easier. In the last decade, several solutions for resolving this problem have emerged in the literature, and they have shown positive incremental advancements in this fieldof study. The nuclear atypia count is an important measure to consider when assessing breast cancer. This work provides a comprehensive review of automated nuclear atypia scoring process which includes the current advancements and future prospects for this critical undertaking, which will aid humanity in the fight against cancer. In this study, we examine the various techniques applied in detecting nuclear atypiain breast cancer as well as the major hurdles that must be overcome and the use of benchmark datasets in this domain. This work provides a comprehensive review of automated nuclear atypia scoring process which includes the current advancements and prospects for this critical undertaking, which will aid humanity in the fight against cancer. 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Lecture Notes in Networks and Systems, Vol-563, pp. 717-740.
Varghese J., Department of Computer Science, Christ Deemed to Be University, Karnataka, Bengaluru, 560029, India, Christ Academy Institute for Advanced Studies, Karnataka, Bengaluru, 560083, India; Saleema J.S., Department of Computer Science, Christ Deemed to Be University, Karnataka, Bengaluru, 560029, India
Therapeutic effects of vitamin D and cancer: An overview
calcitriol; cancer; cholecalciferol; single nucleotide polymorphism; vitamin D
Since vitamin D's discovery, strenuous efforts to investigate its physiological exploit and deficiency on human health were done. Our body synthesizes fat-soluble vitamin D when get exposed to sunlight. In recent years, experimental data indicate that sunlight exposure and an adequate level of circulating vitamin D can reduce the incidence of cancer. Several in vitro and in vivo studies also suggest vitamin D as a potentially valuable supplement for cancer treatment and prevention. Nevertheless, there need to be adequate clinical studies performed to substantiate the suppressive ability of vitamin D concerning cancer incidence. Thus, understanding the cellular mechanisms of vitamin D can be advantageous for preventing several chronic diseases. Consequently, this review concentrates on different studies that have been conducted to characterize the outcome of vitamin D in reducing cancer incidence and its medication by cellular progression mechanism. 2021 The Authors. Food Frontiers published by John Wiley & Sons Australia, Ltd and Nanchang University, Northwest University, Jiangsu University, Zhejiang University, Fujian Agriculture and Forestry University.
Varghese J.E.; Balasubramanian B.; Velayuthaprabhu S.; Thirunavukkarasu V.; Rengarajan R.L.; Murugesh E.; Manikandan P.; Arun M.; Anand A.V.
Food Frontiers, Vol-2, No. 4, pp. 417-425.
https://doi.org/10.1002/fft2.97 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85129110909&doi=10.1002%2ffft2.97&partnerID=40&md5=a9e3d93675ddfc75ae395e10da6e7c05
Varghese J.E., Department of Human Genetics and Molecular Biology, Bharathiar University, Tamil Nadu, India; Balasubramanian B., Department of Food Science and Biotechnology, College of Life Science, Sejong University, Seoul, South Korea; Velayuthaprabhu S., Department of Biotechnology, Bharathiar University, Tamil Nadu, India; Thirunavukkarasu V., Department of Biotechnology, Bharathiar University, Tamil Nadu, India; Rengarajan R.L., Department of Animal Science, Bharathidasan University, Tamil Nadu, India; Murugesh E., Nutritional Improvement of Crops, International Centre for Genetic Engineering and Biotechnology, New Delhi, India; Manikandan P., Department of Life Sciences, CHRIST (Deemed to be University), Karnataka, India; Arun M., Department of Life Sciences, CHRIST (Deemed to be University), Karnataka, India; Anand A.V., Department of Human Genetics and Molecular Biology, Bharathiar University, Tamil Nadu, India
Revisiting psychotherapeutic practices in Karnataka, India: Lessons from indigenous healing methods
India; Indigenous healing; Karnataka; Mental illness; Psychotherapy
Psychotherapeutic practices in India observes a paradigm shift with the current focus on the indigenous movement which has hit the discipline of Psychology like any other stream in Social Sciences and Humanities. The professional challenges and issues faced by the mental health professionals in this country has always revolved around on the 'uncanny' realm of myths, beliefs and religions as far as mental illness is concerned (Prasadarao & Sudhir, 2001). Efforts have been initiated in exploring the cultural and social roots of the health-illness constructs as well as debating on the possibility of 'integration' of these different philosophies. This paper is designed to understand the various therapeutic forms and processes in indigenous healing practices and to analyse the negotiation between indigenous healing practices and psychotherapy with special reference to Karnataka, one of the States situated in the Southern part of India. The study approaches the cultural landscape of Karnataka state based on a qualitative research design wherein in-depth unstructured interview of healers and mental health practitioners and systematic observation of some indigenous healing forms are adopted as methods of data collection. The paper concludes by looking at the challenges of constructing ethnospecific interventions in psychotherapy and the need to develop more cultural-specific theories taking into account the cultural history of the community.
International Journal of Health Promotion and Education, Vol-49, No. 3, pp. 128-136.
Institute of Health Promotion and Education
Varghese K.J., Department of Psychology, Christ University, Bangalore 29, India; Gopal B., Department of Psychology, Christ University, Bangalore 29, India; Thomas T.M., Department of Psychology, Christ University, Bangalore 29, India
Antibacterial efficiency of carbon dots against Gram-positive and Gram-negative bacteria: A review
Antibacterial mechanisms; Antibiotic resistance; Carbon dot; Gram-positive and Gram-negative bacteria; Modified carbon dots; ROS
The nontoxic characteristics and inherent antibacterial potency of Carbon dots (CDs) have earned immense attention in the last few years. As the increasing antibiotic resistance of bacterial strains create critical health risks, replacement of conventional antibiotics with alternative antibacterial agents is highly encouraged. The light-driven antibacterial action CDs is a safe process with minimal side effects. Direct interaction of CDs with bacterial cells also contribute to the overall antibacterial activity. Unique and complex mechanisms of antibacterial activity of CDs involve ROS generation, degeneration of cell structure, and leakage of the cytoplasm because of DNA binding and modulation of gene expression. This review provides a systematic overview of the antibacterial potency of CDs to eradicate Gram-positive and Gram-negative bacteria. Various mechanisms of antibacterial activity and factors that contribute to antibacterial action of CDs also discussed. It also highlights the synergistic effects on the antibacterial performance of modified CDs and significant future research concerns. 2021 Elsevier Ltd
Journal of Environmental Chemical Engineering, Vol-9, No. 6
https://doi.org/10.1016/j.jece.2021.106821 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85120323488&doi=10.1016%2fj.jece.2021.106821&partnerID=40&md5=23cbc60d77c4f36c6414becdbed9a9fa
Varghese M., Department of Physics and Electronics, CHRIST (Deemed to be University), Bengaluru, 560029, Karnataka, India; Balachandran M., Department of Physics and Electronics, CHRIST (Deemed to be University), Bengaluru, 560029, Karnataka, India
Family Caregiving in Dementia in India: Challenges and Emerging Issues
Challenges in caregiving; Dementia; Emerging issues; Family caregiving; Family-based interventions; India
This chapter would provide an overview of the caregiving scenario in India with a focus on families as the mainstay of support and care for people with dementia. The various aspects of caregiving in dementia would be discussed in the light of the Indian sociocultural context. The impact of caregiving and challenges faced by the family and informal caregivers would be described in the light of the changing demographics and urbanization in India. The need for different kinds of caregiver education and training programmes tailored to the domiciliary and socioeconomic status of the family would be discussed. The resources available for family caregivers, like existing programmes for psychoeducation, family self-care, online and other resources for support would be described. We would discuss the challenges faced in developing culturally appropriate interventions for India that can be delivered within existing resources, such as supporting families in their role as caregivers and providing training and support for them. The chapter would discuss the emerging issues in the models of care for low- and middle-income countries like India, where the care is primarily home-based. The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.
Dementia Care: Issues, Responses and International Perspectives, pp. 121-136.
Varghese M., Geriatric Clinic and Services, Department of Psychiatry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, 560029, India; Baruah U., Geriatric Clinic and Services, Department of Psychiatry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, 560029, India, Department of Psychology, Christ (Deemed to be University), Bangalore, 560029, India; Loganathan S., Geriatric Clinic and Services, Department of Psychiatry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, 560029, India
Citrus Medica-derived Fluorescent Carbon Dots for the Imaging of Vigna Radiate Root Cells
Bioimaging; Carbon dots; Citrus medica; Fluorescence; Hydrothermal Method; Root Cells
Bio-imaging is a crucial tool for researchers in the fields of cell biology and developmental biomedical sector. Among the various available imaging techniques, fluorescence based imaging stands out due to its high sensitivity and specificity. However, traditional fluorescent materials used in biological imaging often suffer from issues such as photostability and biocompatibility. Moreover, plant tissues contain compounds that cause autofluorescence and light scattering, which can hinder fluorescence microscopy effectiveness. This study explores the development of fluorescent carbon dots (Cm-CDs) synthesized from Citrus medica fruit extract for the fluorescence imaging of Vigna radiata root cells. The successful synthesis of CDs with an average size of 6.7nm is confirmed by Transmission Electron Microscopy (TEM). The X-ray diffraction (XRD) analysis and raman spectroscopy indicated that the obtained CDs are amorphous in nature. The presence of various functional groups on the surface of CDs were identified by Fourier transform infrared (FTIR) spectra. The optical characteristics of Cm-CDs were studied by UV-Visible spectroscopy and photoluminescence spectroscopy. Cm-CDs demonstrated strong excitation-dependent fluorescence, good solubility, and effective penetration in to the Vigna radiata root cells with multicolor luminescence, and addressed autofluorescence issues. Additionally, a comparative analysis determined the optimal concentration for high-resolution, multi-color root cell imaging, with Cm-CD2 (2.5mg/ml) exhibiting the highest photoluminescence (PL) intensity. These findings highlight the potential of Cm-CDs in enhancing direct endocytosis and overcoming autofluorescence in plant cell imaging, offering promising advancements for cell biology research. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Varghese M.; Bylappa Y.; Nag A.; Kumbhakar P.; Balachandran M.
Varghese M., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India; Bylappa Y., Department of Life Sciences, Christ University, Karnataka, Bengaluru, 560029, India; Nag A., Department of Life Sciences, Christ University, Karnataka, Bengaluru, 560029, India; Kumbhakar P., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India; Balachandran M., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India
Bio-waste derived multifunctional carbon dots for white light generation, forensic and antibacterial applications
Carbon dots; Green synthesis; Latent fingerprint; Solid-state fluorescence; White light-emitting diode
The synthesis of multi-colour emitting solid-state fluorescent (SSF) carbon dots (CDs) is a challenging task due to the phenomenon of aggregation-induced self-quenching. However, this study presents an efficacious method to synthesize CDs from the sap stain of the cupressus lusitanica tree (cl-CDs) via a simple one-step microwave treatment. The resulting SSF CDs exhibited a particle size of approximately 3 nm, high stability, and remarkable efficacy in light conversion when coated on a UV light emitting diode (UV LED). The ensuing coating generated white light with CIE colour coordinates of (0.33, 0.34) and a high luminescence efficiency of approximately 671 L/W. The fluorescence capabilities exhibited by the cl-CDs in response to 254 nm and 365 nm UV light excitation make them an ideal choice for developing fluorescent inks to prevent counterfeiting. Moreover, the study investigated the notable fluorescence properties of cl-CDs as a luminescent fingerprint powder for the recognition of latent fingerprints on various surfaces. Additionally, the antibacterial potential of cl-CDs was evaluated against gram-positive and gram-negative bacteria, where the cl-CDs were utilized as an antibacterial dusting powder for fluorescent imaging of latent fingerprints on different substrates. Therefore, we believe that our present work offers a plethora of exciting possibilities for the multifunctional application of SSF green CDs with significant implications in white light generation, counterfeiting prevention, forensic applications, and healthcare. 2024 Elsevier B.V.
Varghese M.; Jayaram S.; Sarojini S.; Kumbhakar P.; Balachandran M.
Journal of Photochemistry and Photobiology A: Chemistry, Vol-450
https://doi.org/10.1016/j.jphotochem.2023.115456 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85182522232&doi=10.1016%2fj.jphotochem.2023.115456&partnerID=40&md5=b779cb01230a8bb6f7e7e9a907cbd5cf
Varghese M., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bengaluru, 560029, India; Jayaram S., Department of Life Sciences, CHRIST (Deemed to be University), Karnataka, Bengaluru, 560029, India; Sarojini S., Department of Life Sciences, CHRIST (Deemed to be University), Karnataka, Bengaluru, 560029, India; Kumbhakar P., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bengaluru, 560029, India; Balachandran M., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bengaluru, 560029, India
Antibacterial Effect of Phosphorous-Doped Carbon Nanomaterial Derived from Alstonia Venenata
Antibacterial; Antibiotic resistance; Carbon nanomaterials
Antibiotics have been widely used as fundamental medicine for several decades to treat various bacterial infections. However, bacteria develop different mechanisms to defeat the action of antibiotics, which has become a significant issue that endangers infectious therapy. To reduce the consumption of antibiotics and thus combat the increasing antibiotic resistance, it is necessary to implement safe and effective alternatives to conventional antibiotics. Though nanomaterials have become an emerging hope in infectious treatments, they have limited application due to aggregation, toxicity issues, and problems related to their dispersibility. However, carbon nanomaterials (CNMs) offer high solubility, biocompatibility, and minimum toxicity with their inherent antibacterial properties. The selection of natural precursors as the carbon source is an eco-friendly and economical route for synthesizing antibacterial carbon nanomaterials. In the present work, fluorescent CNMs have been synthesized by the hydrothermal treatment of Alstonia venenata leaf extract. The antibacterial capability of the bare extract (AVE), hydrothermally treated extract (AVH), AVH doped with nitrogen (N-AVH), and AVH doped with phosphorous (P-AVH) are tested against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) bacteria. Except for P-AVH, all other samples showed nontoxicity towards the tested bacterial species. In contrast, P-AVH inhibited bacterial growth with minimum inhibitory concentration (MIC) values of 2.5 and 2mg/ml on S. aureus and E. coli, respectively. 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Varghese M.; Kootery K.P.; Sarojini S.; Balachandran M.
Springer Proceedings in Materials, Vol-28, pp. 327-331.
Varghese M., Department of Physics and Electronics, Christ University, Bengaluru, India; Kootery K.P., Department of Life Sciences, Christ University, Bengaluru, India; Sarojini S., Department of Life Sciences, Christ University, Bengaluru, India; Balachandran M., Department of Physics and Electronics, Christ University, Bengaluru, India
Nanocomposites in Combating Antimicrobial Resistance
AMR; Antibacterial; Nanocomposite; Synergistic effect
Extensive and improper usage of antibiotics has resulted in the outbreak of multidrugresistant microorganisms and increasing antimicrobial resistance (AMR), which has become a significant threat to global health and health care. Resistant microorganisms adapt various resistance mechanisms like modifying the structure of antibiotics, altering the target, inhibiting the internalization of antibiotics, ejection of antibiotics from bacterial cells, etc. By lowering or completely disabling the efficacy of antibiotics, AMR may become a primary cause of mortality if left unattended. Developing effective antiresistance strategies to combat AMR is an urgent need of time. Nanomaterials have great potential to inactivate pathogens, and their mechanism of antimicrobial activity is different from antibiotics. With these unique mechanisms of antimicrobial action, nanomaterials are less prone to develop AMR. Developing nanocomposites can provide synergistic effects to improve the properties and strengthen the antimicrobial capability of individual nanomaterials. In this chapter, contemporary developments in the application of antimicrobial composites such as carbon nanocomposites, metallic nanocomposites, nonmetallic nanocomposites, metalloid nanocomposites, polymer nanocomposites, ceramic nanocomposites, and their hybrid forms to prevent the evolution of AMR will be discussed. The current research direction, prospects, and possible strategies to explore nanocomposites as potent antimicrobial agents to conquer AMR will be highlighted. The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Varghese M.; Mathew A.A.; Balachandran M.
Nanotechnology Based Strategies for Combating Antimicrobial Resistance, pp. 203-230.
Varghese M., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bengaluru, India; Mathew A.A., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bengaluru, India; Balachandran M., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bengaluru, India
Carbon dots-Zno/TiO2 ternary nanocomposite as a proficient material to enhance the performance of natural DSSC
Carbon dots; Co-activation; Composites; DSSC; Natural dye; Stability
A novel sustainable approach for enhancing the efficiency of dye-sensitized solar cells (DSSCs) involves the utilization of a combination of ZnO and carbon dots (CDs) derived from Citrus medica fruit extract, along with microwave-synthesized TiO2 nanoparticles for the preparation of the photoanode. Natural dyes such as Hibiscus rosa-sinensis and Allium Cepa peel are employed as sensitizers to reduce production costs. This co-activation method has demonstrated a significant improvement in the output parameters of the devices. Notably, the photoanode co-activated with ZnO-CD composite (ZnO-CD/TiO2) exhibits the most favorable output parameters when combined with Hibiscus rosa-sinensis dye (open circuit voltage (Voc) = 0.80 V, short circuit current density (Jsc) = 6.62 mA/cm2, fill factor (FF) = 64.20 %, photo conversion efficiency (PCE) = 3.40 %) and Allium Cepa peel dye (Voc = 0.81 V, Jsc = 6.79 mA/cm2, FF = 65.70 %, PCE = 3.61 %). When paired with Allium Cepa dye, the CD modified photoanode (CD/TiO2) offers Voc = 0.73 V, Jsc = 6.64 mA/cm2, FF = 61.27 % and PCE = 2.97 %. Similarly, when combined with Hibiscus rosa-sinensis dye, the output parameters of the CD/TiO2 photoanode are Voc = 0.72 V, Jsc = 6.54 mA/cm2, FF = 64.4 % and PCE = 3.03 %. In comparison to all tested devices, the unmodified photoanode (TiO2) displayed the lowest performance, with parameters such as Voc = 0.59 V, Jsc = 6.45 mA/cm2, FF = 52.5 %, PCE = 2.10 % using Allium Cepa peel dye, and Voc = 0.66 V, Jsc = 6 mA/cm2, FF = 51.60 %, PCE = 2.04 % using Hibiscus rosa-sinensis dye. Furthermore, the co-activation process has been shown to enhance the stability of the devices. While the unmodified photoanodes ceased to operate after eight days, the ZnO-CD composite co-activated photoanodes retained their initial efficiencies up to 61.50 % and 68.53 % with the Allium Cepa peel dye and Hibiscus rosa-sinensis dye, respectively. Therefore, this study underscores the potential of the synthesized composite material in enhancing the performance of natural DSSCs. 2024 Elsevier Ltd
Varghese M.; Ninan G.G.; Balachandran M.
https://doi.org/10.1016/j.micrna.2024.207934 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85199681046&doi=10.1016%2fj.micrna.2024.207934&partnerID=40&md5=952a0e7bc28d64a5b090137415208eb1
Varghese M., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India; Ninan G.G., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India; Balachandran M., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India
Cocos nucifera L.-derived porous carbon nanospheres/ZnO composites for energy harvesting and antibacterial applications
Antibacterial activity; Carbon nanomaterials; Counter electrode; DSSC; Green synthesis
Carbon nanomaterials (CNMs) have been the subject of extensive research for their potential applications in various fields, including photovoltaics and medicine. In recent years, researchers have focused their attention on CNMs as their high electrical conductivity, low cost, and large surface area are promising in replacing traditional platinum-based counter electrodes in dye-sensitized solar cells (DSSC). In addition to their electrical properties, CNMs have also displayed antibacterial activity, making them an attractive option for medical applications. The combination of CNMs with metal oxides to form composite materials represents a promising approach with significant potential in various fields, including energy and biology. Here, we introduce porous carbon nanospheres (PCNS) derived from Cocos nucifera L. and its ZnO composite (PCNS/ZnO) as an alternative material, which opens up new research insights for platinum-free counter electrodes. Bifacial DSSCs produced using PCNS-based counter electrodes achieved power conversion efficiencies (PCE) of 3.98% and 2.02% for front and rear illumination, respectively. However, with PCNS/ZnO composite-based counter electrodes, the efficiency of the device increased significantly, producing approximately 5.18% and 4.26% for front and rear illumination, respectively. Moreover, these CNMs have shown potential as antibacterial agents. Compared to PCNS, PCNS/ZnO composites exhibited slightly superior antibacterial activity against tested bacterial strains, including gram-positive Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus), and gram-negative Vibrio harveyi (V. harveyi) and Escherichia coli (E. coli) with MIC values of 125, 250, 125, and 62.5g/ml, respectively. It is plausible that the outcomes observed were influenced by the synergistic effects of the composite material. Graphical abstract: (Figure presented.) The Author(s), under exclusive licence to Korean Carbon Society 2024.
Varghese M.; Ninan G.G.; Jayaram S.; Sarojini S.; Balachandran M.
Carbon Letters, Vol-34, No. 5, pp. 1399-1411.
Varghese M., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India; Ninan G.G., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India; Jayaram S., Department of Life Sciences, Christ University, Karnataka, Bengaluru, 560029, India; Sarojini S., Department of Life Sciences, Christ University, Karnataka, Bengaluru, 560029, India; Balachandran M., Department of Physics and Electronics, Christ University, Karnataka, Bengaluru, 560029, India
Challenging the Representation of the HumanAnimal Relationship in The Elephant Whisperers
Economic and Political Weekly, Vol-58, No. 25-26, pp. 89-90.
Varghese N., The Department of English and Cultural Studies, Christ University, Bengaluru, India
Fluorescent carbon nanoparticle hybrids: synthesis, properties and applications
Applications; Fluorescent hybrid carbon nanoparticles; Functional properties; Properties; Synthesis
The development of materials in nanoscale morphologies with novel compositions is one of the major focuses of nanoscience and technology, as these materials are imbibed with unique properties that make them suitable for specific applications in a large variety of fields. Combining two or more chemically distinct constituents into a single nanostructure helps to attain desirable attributes of physical and chemical responses that can be efficiently utilized for specific applications. Hybrid nanomaterials constituted as a combination of multiple components into single nanostructures are known to showcase the properties of the individual components in tandem or synergy. Novel functionalities are also known to arise from integrating Fluorescent carbon nanoparticles (FCNPs) with other counterparts. FCNPs, when combined with other materials to form nanohybrids, provide copious functional attributes due to their inherent properties and the augmentation in properties due to the presence of the other materials. Integrating hybrid counterparts with FCNs improves the functional properties, which can be utilized for various applications such as photocatalysis, bioimaging, bio/chemo sensing, and many more. Herein we present an overview of recent and relevant works related to the synthesis, properties, and applications of fluorescent carbon nanoparticle (FCNP) hybrids. Various synthetic routes of FCNP hybrids via physical and chemical methods are summarized. The properties of the hybrid systems and the influence of hybridization on the properties are discussed. Applications of FCNP hybrids in various fields are also discussed in detail. 2025 Elsevier Inc. All rights are reserved including those for text and data mining AI training and similar technologies.
Varghese N.; John V.L.; Das R.; Sivan M.D.; Remadevi A.B.; Vinod T.P.; Nair Y.
Fluorescent Carbon Nanoparticles: Fundamentals and Applications, pp. 667-722.
Varghese N., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India; John V.L., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India; Das R., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India; Sivan M.D., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India; Remadevi A.B., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India; Vinod T.P., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India; Nair Y., Department of Chemistry, CHRIST (Deemed to be University), Karnataka, Bangalore, India
In vitro Analytical Techniques as Screening Tools to investigate the Metal chelate-DNA interactions
Deoxyribose nucleic acid; Fluorescence spectroscopy; Metal -DNA complex; Molecular docking; UV-Vis spectroscopy
Deoxyribose nucleic acid (DNA) is found to be the most efficient pharmacological target of many synthetic molecules which are deemed as potential drugs with clinical applications. DNA binding agents are known to regulate several cell functions (gene expression and replication) by adopting various protocols which include the annihilation of the cell membrane, interruption in protein synthesis, and irreversible binding to cell receptors. Recently, several studies have explored fundamental aspects of drug-DNA interactions, providing new insights into the driving forces that render the formation of the drug-DNA complex. In order to study and understand these biologically important reaction mechanisms, several screening tools have been devised and the specificity of drug molecules binding to DNA were studied in detail. This review will discuss the utilization of various analytical tools which include UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism, viscosity measurement, Raman spectroscopy, cyclic voltammetry, and DNA fragmentation assay used for studying drug binding mode and the mechanism involved. 2023 Wiley-VCH GmbH.
Varghese N.; Jose J.R.; Krishna P.M.; Philip D.; Joy F.; Vinod T.P.; Prathapachandra Kurup M.R.; Nair Y.
https://doi.org/10.1002/slct.202203615 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85147379568&doi=10.1002%2fslct.202203615&partnerID=40&md5=fac960e4933ae3624ba8375cfdbf05c7
Varghese N., Department of Chemistry, CHRIST (Deemed to be University), Hosur Road, Karnataka, Bengaluru, 560 029, India; Jose J.R., Department of Chemistry, CHRIST (Deemed to be University), Hosur Road, Karnataka, Bengaluru, 560 029, India; Krishna P.M., Department of Chemistry, Ramaiah institute of technology, MSRIT Post, M S Ramaiah Nagar, Karnataka, Bengaluru, 560054, India; Philip D., Department of Chemistry, CHRIST (Deemed to be University), Hosur Road, Karnataka, Bengaluru, 560 029, India; Joy F., Department of Chemistry, CHRIST (Deemed to be University), Hosur Road, Karnataka, Bengaluru, 560 029, India; Vinod T.P., Department of Chemistry, CHRIST (Deemed to be University), Hosur Road, Karnataka, Bengaluru, 560 029, India; Prathapachandra Kurup M.R., Department of Applied Chemistry, Cochin university of science and technology, Kochi, 682022, India; Nair Y., Department of Chemistry, CHRIST (Deemed to be University), Hosur Road, Karnataka, Bengaluru, 560 029, India