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Settlement of Industrial Disputes through Conciliation Machinery - A Critical Comparative Analysis Based on Singapore Model
Get PDFIn the current global scenario, where a developing country like India is still in the path of progression towards economic objectives the base of which lies in designing the industrialisation strategy and the industrial policy promoting industrial harmony, the need for restructuring the dispute resolution machinery keeping pace with global requirements is the need of the hour. In the wake of the New Economic Policy introduced in 1991, time had come for labour policies to synergistically relate to the industrial policies so that both move in a unified direction rather than the opposite directions.
The transition from the old labour law regime to new labour law regime with the passing of the new Labour Codes inclusive of the Industrial Relations Code, 2020 aims at well-being of our industrious workers and accelerate the pace of the economic growth. This research work is done to understand the issues and challenges in the effective functioning of the Conciliation Machinery in the industrial dispute resolution process. The researcher in this study has shared an imprint of wide range of issues relevant to the study through the review of past literature. This helped the researcher to identify the gaps in the study.
The researcher has critically evaluated the functioning of the Conciliation Machinery as given under the Industrial Disputes Act of 1947 and critically analysed whether the new Industrial Relations Code, 2020 is effective in terms of the challenges posed by the existing regime and suggest measures for the efficacy of the ‘Conciliation Machinery’. The researcher also critically analysed the success model of Conciliation in dispute resolution process of Singapore Tripartism Framework to identify the parameters from that model.
This study was conducted through doctrinal research method. Through the identified parameters from the Singapore model, the researcher also analysed the feasibility of incorporating the same into the Indian industrial context for the success of Conciliation Machinery in India. Incorporating such reforms, the Conciliation machinery’s performance will be positive in bringing about industrial peace and harmony in industrial relations
Development of Novel Nanocarriers with Multi modal Action against Lung Cancer
No full textLung cancer ranks among the top causes of cancer-related deaths worldwide. The deteriorating environment and unhealthy lifestyle in the modern era has further contributed to the exponential increase in lung cancer incidence across the globe. Lung cancers fall under two major types based on the location of the tumour in the lung namely, small-cell lung cancer (SCLC) which is more aggressive, and non-small-cell lung cancer (NSCLC) which is more prevalent. Late diagnosis has been a major cause for poor prognosis as the cancer is detected only in an advanced stage.
Conventional therapies like chemotherapy, surgery and radiotherapy against lung cancer are limited by their adverse effects and inability to completely destroy the cancer cells at advanced stages. Additional barriers for therapeutic interventions are presented by the tumour which reprogrammes its microenvironment through recruiting immune cells and fibroblasts that transform into sentinels protecting the tumour cells and suppressing cytotoxic effects of immune cells and therapeutic agents leading to the poor therapeutic outcomes.
In recent years, molecular modulation strategies have gained momentum to overcome the barriers presented by the formidable tumour microenvironment and halting the tumour progression. The present study adopts a multi-modal approach integrating the beneficial properties of gene silencing, immunotherapy, and nanotechnology. One of the key players in this reprogramming is the vascular endothelial growth factor (VEGF) which plays a multi-faceted role in tumour progression and metastasis. We have chosen to partially silence this gene in the tumour cells using a polyplex formed from the biocompatible poly(1-vinylimidazole) with anti-VEGF si-RNA.
Our in vitro studies revealed that the polyplex exhibited superior internalization, endosomal escape and VEGF silencing ability when compared to the free si-RNA in both human derived A549 lung carcinoma cells and mouse derived LL2/LLC Lewis lung carcinoma cells. The polyplex also was capable of rapid internalization into 3D tumour spheroids developed using the overlay method with A549 cells and Matrigel® and silence the target gene. VEGF silencing inhibited the migration of cancer cells and sensitized cancer cells to chemotherapeutic agents. Co-culture studies with Jurkat T-lymphocytes revealed that VEGF silencing enhanced proliferation of Jurkat cells while suppressing cancer cell numbers indicating that VEGF silencing could significantly improve the outcomes of immunotherapy.
We attempted to harness the cytotoxicity of the cell-based immune system to destroy cancer cells. To help the immune cells distinguish cancer cells from normal cells, we employed chitosan nanoparticles conjugated with a MUC1 peptide as a synthetic antigen-presenting entity to trigger the immune response against cancer cells. MUC1 is over-expressed in lung cancer cells and hence we used a 25-mer peptide fragment from MUC1 which could serve as an antigenic epitope to prime the immune cells.
Since, cytotoxicity of the immune cells cannot be realized in the immune-suppressive tumor microenvironment, we used a temporally regulated approach by first silencing the VEGF using the polyplex followed by administration of the MUC1-tagged chitosan nanoparticles. Co-culture studies performed with mouse lung carcinoma cells and mouse macrophages revealed that the multi-modal combination of VEGF silencing and MUC1 presentation activated the M1 phenotype of macrophages and inhibited the epithelial-to-mesenchymal transition of lung cancer cells apart from causing a marked reduction in the tumour cell numbers. In vivo studies performed in an orthotopic lung cancer model in immune-competent C57BL/6 mice confirmed that the combination therapy reduced tumour progression as well as metastasis and restored the normal lung architecture. The VEGF silencing was accompanied by reduction in HIF-1, IL-10, IL-6 and TNF- clearly indicating that this nano-geno-immunotherapy could be a promising therapeutic option for treatment of lung cancers
Biofabrication of Tissue Constructs Using Protein-in-Polysaccharide Bioinks for Muscle Regeneration
No full textMyocardial infarction (MI) and volumetric muscle loss (VML) are debilitating conditions that severely affect patient quality of life and challenge healthcare systems, particularly in diagnosis and treatment. Conventional therapies often result in long recovery periods with limited functional restoration. Advances in regenerative medicine, especially extrusion-based 3D bioprinting, offer promising potential to improve the regeneration of complex tissues by precisely depositing cells and biomaterials layer-by-layer to create tailored tissue constructs.
A critical challenge in muscle tissue regeneration is developing protein-polysaccharide bioinks that closely mimic the native muscle tissue microenvironment. In this study, two protein-inpolysaccharide bioinks (alginate-fibrinogen and methylcellulose-gelatin-alginate) were developed to replicate the extracellular matrix of muscle tissues and evaluated for their ability to support muscle cell viability and functionality. Although the alginatefibrinogen bioink maintained cardiomyocyte viability, it failed to restore functionality.
To address the limitations of the Alg/fib bioink, a methylcellulose-gelatin-alginate bioink was developed, offering improved handleability, enhanced cell-cell and cellmaterial interactions, and maintained cardiomyocyte viability. However, it still failed to restore cardiomyocyte functionality. Alternatively, the methylcellulose-gelatinalginate bioink was tested for skeletal muscle regeneration by incorporating muscle cells and evaluating myotube formation and muscle-specific markers in vitro.
In vivo studies in mouse VML models demonstrated that bioprinted muscle tissue constructs (BMTCs) promoted functional recovery, enhancing vascularization and innervation. These results suggested that BMTCs held significant potential for treating VML injuries, with outcomes comparable to autologous minced muscle
Next Generation Sequencing based Profiling of Genes in Patients with Syndromic forms of Retinitis Pigmentosa
No full textIndia is one of the largest populations in the world and is estimated to have a high prevalence of Retinitis Pigmentosa (RP). RP is clinically and genetically heterogenous, characterized initially as night blindness, leading to complete vision loss due to retinal degeneration. RP can occur in non-syndromic or syndromic forms, affecting other organs as observed in Bardet Biedl Syndrome (BBS) and Usher syndrome (USH).
BBS is characterized by RP, polydactyly, obesity, renal anomalies and learning difficulties. USH is characterized by RP and sensorineural hearing loss (SNHL), with variable presence of vestibular dysfunction. Nextgeneration sequencing (NGS) has become a cost-effective technology for rapid and accurate data generation and analysis in genetic studies.
In this study, NGS was used to screen patients clinically diagnosed with syndromic RP and Leber Congenital Amaurosis (LCA)/Severe Early Congenital Onset Retinal Degeneration (SECORD)) after detailed ophthalmic examinations and documentation of extraocular features through a proforma and questionnaire.
A total of 207 (N=108 BBS, N=90 USH and N=9 retrospective SECORD) patients were analysed for genetic etiology; pathogenic variations were identified in 85% of BBS and 84% of USH in known genes; N= 48 in BBS and N=36 in USH were novel variations. Eleven patients showed variations in other IRD and ciliary genes (3 BBS and 8 USH); noncandidate gene variations were identified in 5 BBS and 3 USH patients through whole exome sequencing; however, the disease causal role of these variations deems further clinical evaluation and correlation.
Genetic alterations were not identified in 9% and 6% of BBS and USH patients respectively. The study also revealed the potential of NGS in re-diagnosis of syndromic forms of LCA/SECORD in patients who were initially diagnosed as isolated RP cases. The study has expanded the knowledge on genetic spectrum of BBS and USH patients from India and is the only available report from the country.
This study gains momentum in the context of emerging gene based therapeutic interventions and also validates the need for early molecular diagnosis, which will aid in the (i) management of syndromic conditions (ii) confirmation of disease pathogenesis through differential diagnosis based on the genes identified
Reconfigurable Metasurface for 5G & Beyond Wireless Communication
No full textThe potential new applications and increasing demands of future 5th generation (5G) and beyond wireless communication indicate a promising future for mobile communications. However, the transmission medium has traditionally been seen as an unpredictable factor between the sender and receiver. As we enter the digital era of wireless communications, signal quality is deteriorating due to environmental interferences.
With the continuous advancement of technology, there is an increasing need for advanced solutions that can handle complex applications such as haptic communications, the Internet of Things for smart cities, automation, and manufacturing. One technology that has received much attention is the reconfigurable metasurface for reconfigurable intelligent surfaces (RIS). Using reconfigurable metasurfaces provides benefits such as low cost, low power consumption, and improved communication coverage and quality. The RIS demands simple configuration, angular stability, and polarisation insensitivity.
Over the past twenty years, there has been significant advancement in the concept of metasurface, leading to unprecedented possibilities. The initial version involved regular homogeneous periodic structures, notably impacting various application fields, from radio to optical frequencies. Subsequently, a second generation comprising inhomogeneous quasi-periodical or gradient-like arrangements emerged. This spatial modulation enhanced capabilities by offering more degrees of freedom.
Finally, the third generation includes thin patterned structures with controllable properties in space and time through different control mechanisms and advancements in integration technologies, such as electronic, optical, thermal, chemical principles and liquid crystal-based methods. These developments enable the creation of tunable programmable structures for diverse applications. This research will present a design of third generations metasurface with a detailed focus on reconfigurable techniques.
This article introduces a reconfigurable combined loop metasurface, operating at 15.48 GHz covering the Ku band, that can effectively characterize the EM response. This is achieved by incorporating PIN diodes in the meta-atoms on a periodic array within a single-layer metallic structure. By controlling the state of the PIN diodes, the metasurface can achieve various performances viz phase reconfigurability, simultaneous transmission & reflection modes of operation. The proposed structure has validated a 32 × 32 metasurface through numerical simulations and experiments that exhibit promising results, demonstrating its potential for use in 6G applications
Development of Bifunctional Electrocatalyst for the Electrically Rechargeable Zinc Air Batteries
No full textThe spontaneous reaction between zinc and oxygen in an alkaline medium is exploited in non-rechargeable aqueous zinc-air batteries (ZABs) to generate useful electricity. The primary ZAB has a rich history as it was used in tramways, railway signalling and it is being used in hearing aids, pacemakers, etc. The success of primary ZABs led to the development of two types of rechargeable ZAB, namely, mechanically rechargeable ZAB (mrZAB) and electrically rechargeable ZAB (erZAB). In mrZABs, the exhausted anode and electrolyte are replaced periodically. Whereas the chemistry of primary ZAB is reversed using suitable electrocatalysts in erZABs. Electrocatalysts used in erZABs catalyse the oxygen evolution reaction (OER) during recharging and the oxygen reduction reaction (ORR) during discharging and thus improve the overall performance. Noble metals, metal oxides and carbonaceous materials are the most studied electrocatalysts for erZABs. Among these electrocatalysts, noble metals are considered a benchmark. However, the high cost and scarcity of noble metals have limited their large-scale production. This has triggered the research on developing highly active bifunctional electrocatalysts from earth-abundant materials.
On the other hand, the coulombic efficiency of erZAB is always less than 100% due to hydrogen evolution reaction (HER) and concurrent corrosion of zinc (Reaction 1 and 2). This is attributed to the fact that the standard reduction potential of Zn/ZnO (-1.26 V vs SHE) is more negative than that of HER (-0.83 V vs SHE) at pH=14.
2H2O(l) + 2e- → 2OH-(aq) + H2(g) Reaction 1
Zn(s) + H2O(l) → ZnO(s) + H2(g) Reaction 2
The concurrent corrosion of zinc not only decreases the performance of erZAB but also affects the cycling stability. Hence, the overall objective of the thesis is to develop bifunctional electrocatalysts for the erZABs and to inhibit the zinc corrosion thus improving the coulombic efficiency.
MnO2 is one of the most extensively studied transition metal oxides for erZABs and it exhibits polymorphism. There are a few reports on the effect of the crystal structure of MnO2 on the kinetics of ORR. However, the textural properties of various forms of MnO2 are not similar. In addition, the effect of crystal structure on the OER activity is not documented. The experimental conditions were carefully optimized to get different forms of MnO2 with similar textural properties and the effect of the crystal structure of MnO2 (, , , and ) on the kinetics of both ORR and OER was carefully investigated. The ORR activity follows the order: α-MnO2 \u3e δ-MnO2 \u3e λ-MnO2 \u3e β-MnO2 \u3e γ-MnO2 and the OER activity follows the order: α-MnO2 \u3e δ-MnO2 \u3e γ-MnO2 ≈ λ-MnO2 \u3e β-MnO2. Among the five forms of MnO2, α-MnO2 with a large tunnel along with a higher percentage of oxygen-based functionalities on the surface provides more active sites for adsorption and facilitate electron transfer, thereby outperforming other forms of MnO2 towards ORR and OER.
Among various crystallographic forms, α-MnO2 exhibited the best catalytic activity towards ORR and OER. However, its performance is still inferior to the benchmark ORR and OER catalysts. To improve the electrocatalytic activity of α-MnO2, the surface oxygen vacancies (OVs) were tailored by heat treatment and by doping. On heating in air, the surface OVs of -MnO2 are found to increase. For instance, the surface OVs of -MnO2 heated at 500 °C in the air is more than 3 times of surface OVs of as-prepared MnO2. While the ORR activity of -MnO2 heated at 500 °C in air is comparable to the benchmark ORR catalyst, Pt/C, the OER activity is inferior to the benchmark OER catalyst, RuO2. The surface OVs were further increased by doping with Cu2+. 2 wt% Cu2+-doped MnO2 outperforms both the ORR and OER benchmark catalysts.
Activated carbon (AC) is used by various industries such as chemical, agricultural, pharmaceutical, oil refineries, metallurgical, etc., for purification of water, air, deodorization, decoloration, decontamination, separation and purification of solvents and gases, sewage treatment, as energy storage materials, catalysts and catalytic supports, etc. Some of the spent activated carbon (SAC) from the industries are either regenerated or co-fired with coal to generate energy. But, much of the waste is either illegally burnt, thereby contributing to air pollution and smoke haze, or simply left to decay in dedicated landfills emitting potent greenhouse gases. Following the principles of sustainable development goals, a process to convert SAC waste to nanocomposites imbued with electrocatalytic activities is demonstrated in chapter 4. The SAC from an exhausted water filter is converted into MnO2/C nanocomposites by hydrothermal reaction with KMnO4 of different concentrations and used as electrocatalysts for ORR and OER. MnO2/C nanocomposite synthesized using KMnO4:SAC ratio of 2:1 demonstrates a good ORR (onset potential: 0.842 V and current density: -8.91 mA cm-2) and OER (overpotential of 425 mV to reach 10 mA cm-2)activities.
Surgical facemasks (SFMs) were used extensively to protect from COVID-19 during a pandemic. The used SFMs are a serious threat to the environment. In general, used SFMs are incinerated or dumped in landfills. Current methods like incineration, steam treatment, plasma treatment and microwave treatment yield minimal carbon. Therefore, there is a growing need to upcycle waste SFMs into value-added products through safe, environmentally benign processes. Given this, the research community explored a few methodologies to repurpose waste SFMs, tackling their environmental impact. Although these methods are effective, most of them utilize only the outer layers of SFMs. In addition, the surface area and porosity are less compared to the commercial AC. In chapter 5, a method to upcycle waste SFMs into very high surface area carbon is demonstrated. The electrocatalytic activities of carbon derived from waste SFMs towards ORR were studied in an alkaline medium. On increasing the activation temperature, the porosity and ORR activity increases. Consequently, carbon derived from upcycling of SFMs with an activation temperature of 950 °C exhibits a very high surface area of 2163 m2 g-1 and excellent ORR activity, similar to benchmark, ORR catalyst, Pt/C.
The performance of erZABs not only depends on the bifunctional electrocatalyst deployed at the air-cathode but also on the HER occurring at the anode. While the rate of ORR and OER improve the performance of ZAB, HER causes zinc corrosion and thereby affects the performance of ZAB. To mitigate HER and concurrent Zn corrosion, the onset and overpotential of HER are increased by the uniform dispersion of carbon nanodots or metal oxide nanoparticles in the native electrolyte (6 M KOH), thereby reducing zinc corrosion. Dispersion of carbon nanodots or 0.1 wt% of SiOx or ZnO nanoparticles increases the HER overpotential to 321, 547 and 679 mV, respectively. The microscopic investigations confirm the inhibition of corrosion and dendritic growth of zinc. Besides these, nanofluid electrolytes enhance the kinetics of ORR and OER, thereby improving the performance of erZABs. Also, nanofluid electrolytes are stable over three months
Corneal Epithelial Tissue Engineering Approaches To Treat Limbal Stem Cell Deficiency
Get PDFA clear healthy cornea is essential for visual acuity. As a self-renewing and regenerating tissue, the corneal epithelium has a stem cell pool, the limbus that acts as its proliferative reservoir. When limbal epithelial stem cells are destroyed or become dysfunctional, a pathological state known as limbal stem cell deficiency (LSCD) manifests. Damaged corneas have been successfully reconstructed by transplanting the cultured limbal epithelial stem cells. Limbal stem cell transplantation (LSCT) is one of the applicable and most challenging procedures in clinical ophthalmology for the reconstruction of the stratified ocular surface epithelium in patients with LSCD. Given the above challenge, the present thesis aims to report a few approaches to the LSCT procedure.
Auto and allograft limbal transplantations are effective in restoring the corneal epithelium, inhibiting inflammation and neovascularization. The combination of limbal and denuded Human Amniotic Membrane (dHAM) transplantation has been shown to improve the surgical outcome in patients with total LSCD. However, a few problems in HAM remained unresolved, such as the sterile storage for longer periods, the thinness of the membrane that affects the suture strength, wrinkling while transplanting, and early degradation of the membrane. The HAM is a collagenous sheet and requires cross-linkers to increase its strength. This study reports on a novel and simple base chemical – aluminium sulphate (Al2So4) as a cross-linking agent. The Al2So4 cross-linked HAM was compared for the physical, chemical, mechanical, and biocompatible properties with dHAM. A better result of the properties in comparison to the conventional scaffold was obtained and with the approval of institutional ethics the cross-linked HAM is used currently for corneal reconstruction.
The ideal properties of the scaffold that can be used for limbal stem cell transplantation should be optically clear, low cost of production, durable, suturable, provide structural integrity to the ocular surface, gas permeable, allow the diffusion of glucose, and proteins, and ions, have antimicrobial properties, biocompatible and biomimetic scaffold. As an alternative is required in place of dHAM, a novel method of isolation and preparation of a collagen based scaffold from fish scales (Fish Scale Collagen - FSC), a renewable biowaste material was reported in this study. The physico-chemical, mechanical, and culture characteristics of FSC were compared with dHAM. The results suggested optically clear with sufficient mechanical properties, biocompatible, and marker gene expression for the growth characterization of limbal epithelial cells. Thus, the use of this biopolymeric, biocompatible collagen based material from a novel biosource for the growth of corneal epithelial cells offers several advantages in terms of eliminating the risk of disease transmission, reducing the inconsistency in tissue composition associated with biological substrates, being able to be custom fabricated to suit specific requirements, and possibly providing a readily available alternative tissue material for clinical use.
A limbal stem cell transplantation clinical trial was performed on a 29-year-old male patient with chemical injury by ex vivo explant cultured corneal epithelial cells on HAM. The graft was rejected after a few days of post-transplantation. The pathological sections of the pannus showed the presence of dense vascular channels with an impression of vascularisation and hemorrhage. Stromal fibroblasts with chronic inflammatory cells and lymphocytes were seen. We strongly believe that the epithelial-mesenchymal transition (EMT) could have happened due to the explant culture method of cultivating the corneal epithelial cells. Thus, we propose a culture method by using collagenase enzyme on the limbal tissue collected from the donor cadaver eyeball and isolating the pigmented limbal epithelial cells.
A comparative study between the conventional explant culture method and collagenase based culture method was conducted. This method has significant growth kinetics, colony forming efficiency, and proliferation capacity. The EMT upregulating genes were found to be downfolded in this novel culture method indicating the absence of EMT. Putative stem cell markers were maintained throughout the culture for a longer period in comparison to the explants culture method. Our technique achieved the isolation of purified corneal epithelial progenitor cells without contamination by fibroblasts, which often interfere with the primary culture of cells isolated from tissues. Thus, this alternative novel method of isolating limbal epithelial cells would avoid corneal graft rejection that happens due to EMT in the LSCT procedure
Analysis of Networks Using Hypergraph Centrality Measures and Other Properties
Get PDFNetwork analysis explores the connections between nodes and evaluates their characteristics across diverse fields such as biological, chemical, social networks and so on. Identifying key nodes within a network is crucial for grasping how information spreads, which has significant applications across multiple fields. This includes studying disease transmission, managing rumours, understanding social leadership, enhancing viral marketing strategies, and monitoring public opinion. Influential nodes play a pivotal role in effectively distributing information throughout the network. The centrality measures are paramount in network analysis that uses various metrics to evaluate the importance of the node. The centrality predicts the characteristics and significance of the nodes in the network.
Initially, this thesis reviewed different centrality measures alongside their respective implementations to illustrate how different centrality metrics comprehensively characterize and predict the significance of nodes in the network. First the chemical network was chosen for analysis using centrality measures of graphs. The combined centrality index (CCI) is proposed to rank isomers of alkanes without degeneracy which shows strong inter-correlation with existing indices EE, J, RVa, and RVb. Similarly, in social and biological network analysis, the relationships between individuals and proteins are modeled using graphs.
However, social and biological interactions often involve complex, multi-way relationships that simple graphs cannot easily capture. To capture these intricate interactions, hypergraphs, xiv the generalization of graphs is employed, that allows edges to connect multiple nodes. Directed hypergraph is constructed for the football network, where hyperedges are the ball passes between players, while in the Wikipedia network, they could represent user votes on specific topics. The upper and lower bounds on the number of hyperedges in directed hypergraphs are determined using degree and betweenness centrality. The influential nodes are identified based on these results, yielding the minimum number of influential nodes required for maximum spreading.
Next, the biological network is analyzed by constructing a directed hypergraph. Initially, a degree centrality-based weight assignment is proposed for the nodes in the biological network, and these weights are then optimized using a genetic algorithm (GA). The proposed method is applied to ten biological and COVID-19 protein-protein interaction (PPI) networks, and obtains the influential proteins that act as critical ones in the biological activities. The identified critical human proteins have a considerable role in viral infections.
Hence, the obtained proteins may help in the discovery of a drug for COVID-19. The pathway interaction analysis in biological networks impacts many functional features of biological entities. So, we have analyzed the pathway interactions of certain diseases, like Parkinson’s, COVID-19, and diabetes PPI’s, and predicted the critical proteins using modified depth-first search and unimodular property of directed hypergraph. The property of unimodular hypergraph clusters the related essential proteins and enzymes, thereby providing potential avenues for disease treatment
Effect of Gas Tungsten Arc Welding Process Variants on the Microstructure and Properties of AZ31B Magnesium Alloy and 304hcu Austenitic Stainless Steel Welds
Get PDFThe automotive and aero sectors seek materials with high specific strength & specific stiffness for enhanced efficiency / emission control. Mg alloys, known for their low density, are used in the as-cast, and wrought forms, depending on the service requirements, and are predominantly used for non-loaded structural parts in varied engineering applications. Welding Mg alloys is of great interest to industry, not only for the fabrication of components but for the repair welding of casting as well. There has been considerable research in the fusion & solid-state welding of Mg alloys. Gas tungsten arc welding (GTAW) has often been preferred for Mg alloys because of adaptability, process stability, and economy. A thorough review of the literature on the fusion welding magnesium alloys by GTA welding suggests that the potential of pulse welding processes & the capabilities in the modern power sources have not yet been fully explored. This research is an attempt to address some of the identified research gaps.
The effects of pulse frequency & the pulse duration ratios on the weldability & structure-property relationships in AZ31B Mg and the use of AC/DC mix pulse welding with different pulse duration ratios were attempted. Pulse GTA welding in Direct Current Electrode Negative (DCEN) mode at lower frequencies yielded deeper penetration welds at different pulse duration ratios. However, the full penetration welds were possible only with the pulse duration ratio of 1:1 for a given heat input. All the welds produced under pulse GTA welding were free from any defects in contrast to the conventional GTA DCEN welds that had microcracks. The grain size of the pulse GTA weld metals were much finer than that obtained with the conventional GTA welding. Further, the pulse GTA weld metals had registered a higher hardness compared to the conventional GTA weld metal & also the parent alloy.
AC/DC mix pulse welding, with the peak current being AC and the base current as DC, gave rise to a much-controlled heat input, yielded shallow penetration welds with no defects. The microstructures were much finer compared to the DC pulse GTA welds. The outcome of the work reveals that the AC/DC mix pulse welding is very promising to be exploited for repair welding of magnesium alloy castings that might have near-surface defects.
High frequency pulse welding with a short / stable arc in ActivArc® mode (AA-HF) in a modern power source was explored to understand the effect of frequency in the range of 100 Hz to 1500 Hz on the resultant microstructures & properties of AZ31B Mg alloy. The arc constriction by the high frequency pulsing in the AA-HF mode could produce deeper penetration welds at frequencies above 800 Hz for a given heat input. The full penetration ActivArc®-high frequency GTA welds had good microstructural features / mechanical properties and allowed 50% enhanced productivity when the welding was done at a frequency of 1500 Hz. This welding process / technique has been found to be very effective for thicker section welding without the issues of cracking in the weldment.
The learnings from the welding of AZ31B Mg alloy using the pulse GTA welding & AA-HF welding were leveraged for the welding alloy 304HCu, a material for the superheater & reheater sections in the supercritical power plants. The AA-HF welding in the autogenous mode resulted in 304HCu welds with a good form factor and a fine dendritic structure with a mix of vermicular & lacy ferrite. Both the pulse GTA welds and the AA-HF welds had overmatched mechanical properties compared to the welds produced by conventional GTA welding. The AA-HF welding looks to be a good choice for welding stainless steels and can be explored further for welding of much thicker sections either in the autogenous mode or with use of fillers based on the need
Mathematics in Sri Rudram of Krishna Yajurveda Taittiriya Samhita
No full textThis thesis is an attempt to bring out the concealed mathematical information in the Vedic text “Śri Rudram”, by applying Vedic Numerical Code to digitally decode the mantras in the Śri Rudram which forms part of the fourth canto of the Krishna Yajur Veda Taittiriya Samhitā.
By converting the letters into numbers, it was possible to handle the concealed information in a mathematical and logical way to successfully arrive at a convincing reason for the traditional practice of chanting Śri Rudram eleven times in a particular prescribed manner; as well as finding the close relationship between the number 11 and Śri Rudra Bhagawan.
That the information is concealed in the lyrics was not brought out in any previously published literature.
Three papers were published by me in international peer reviewed journals of Sanskrit. A few more papers are also ready for publication.
There is a need for such a study to find out whether other Vedic and Sanskrit literatures also have a wealth of information hidden undiscovered.
There is ample scope for further research in this area