Effect of Silicon and Y2O3 on Densification, Mechanical Properties and Isothermal Oxidation Behaviour of W-10Ni-3Co alloys Fabricated by Powder Metallurgy

Tungsten heavy alloys are highly sought after for industrial and military applications due to their exceptional density, strength, and stiffness. They find utility as kinetic energy penetrators, counterweights, and radiation shields. To enhance densification through liquid phase sintering and reduce the sintering temperature, nickel (Ni) and cobalt (Co) are commonly incorporated into tungsten-heavy alloys. Additionally, mechanical alloying can introduce nano Y2O3 particles into the alloy matrix. This results in a uniformly dispersed fine oxide strengthening (ODS) and an extremely refined grain structure, ultimately leading to increased strength at high temperatures and inhibiting recrystallization. The main objective behind the development of ODS tungsten alloys is to raise the maximum operating temperature. Nonetheless, the susceptibility of tungsten to oxidation at elevated temperatures poses a significant challenge. One potential solution to this critical safety concern involves incorporating oxide-forming alloying elements such as silicon (Si), chromium (Cr), and aluminum (Al), which promote the growth of a stable and protective oxide scale. This oxide scale effectively hinders oxidation at high temperatures. In the present study, we have introduced 1, 5, 10, 15, and 20 wt.% of Si into W, WNi, and WNiCo alloys through planetary milling and conventional sintering in hydrogen gas atmosphere at 1500 ⁰C for 2 hours. The alloy phase evolution and microstructure development have been characterized using XRD, SEM, and TEM, and the hardness and compression strength of the alloys are examined using UTM. The addition of Si into tungsten results in the formation of WSi2 and W5Si3 compounds after sintering. The percentage of these silicides increases with more Si addition. Due to the presence of these brittle compounds, the hardness of the material increases, and the compression strength decreases at higher Si percentages. The addition of Ni/Co, along with Si lowers the formation of intermetallics, and the compression strength of the tungsten has been retained in alloys up to 5 wt.% of Si. However, in the case of high wt.% of Si alloys, even in the presence of Ni/Co due to the more pronounced effect of intermetallics, the alloys become more brittle and subjected to early failure under compression test. Hence, alloys up to 5 wt.% of silicon has been selected as the optimum value. Further, 0.3 wt.% of Y2O3 particles are dispersed into WS1, WNS1, and WNCS1 alloys, and the alloys showed higher strength and hardness due to the combined effect of Ni, Co, Si, and Y2O3. The isothermal oxidation tests were performed on the sintered alloys at 800 ⁰C, 1000 ⁰C, and 1200 ⁰C for 10 hours. The activation energy of oxidation is increased with the silicon percentage in the tungsten due to the formation of SiO2 layer on the top of the tungsten. The presence of Ni/Co in the alloys provide more resistance to oxidation by forming NiWO4 and CoWO4 oxide layers in addition to SiO2. The addition of up to 1 wt. % Si along with Ni, Co, and Y2O3, showed the optimum mechanical properties and better oxidation resistance. Selective alloys are synthesized using SPS at 1300 C for 10 min at 50 MPa pressure to observe the effect of consolidation technique on densification, hardness and oxidation properties of alloys

Spectral analysis of Some Sequence-generated Graphs

In the study of graph theory, there are some classes of graphs that can be coded by a sequence, sometimes called the creation sequence. A graph G is called H-free if H is not an induced subgraph of G. Many significant classes of graphs can be described in terms of forbidden subgraphs. They include threshold graphs, chain graphs, cographs, bipartite graphs, perfect graphs, chordal graphs, split graphs, and trees, to name a few. Very interestingly, only a few of them can be generated by a sequence. Trees, threshold graphs, chain graphs, and certain cographs are examples of such graphs. The notion of this sequence is commonly known as binary sequence in the case of threshold graphs and chain graphs. Threshold graph has forbidden subgraphs P4, C4, and 2K2; chain graph has forbidden subgraphs C3, C5 and 2K2; whereas cograph forbids P4. In this thesis, we investigate various spectral properties of these graphs: threshold, chain, and certain cographs. The primary matrices of this study are the adjacency matrix A, the Laplacian matrix L, and the Seidel matrix S. In particular, we analyse the Seidel spectrum of threshold graphs, the spectrum and energy of the Seidel matrix for chain graphs, and the adjacency and Laplacian spectrum of certain cographs. Consider a connected threshold graph G. The threshold graph has several equivalent definitions. In this study, we consider the definition based on binary strings that will be relevant to this work. The underlying matrix is the Seidel matrix S. We compute the determinant and a recurrence formula for the characteristic polynomial of S. A formula for the multiplicity of the Seidel eigenvalues _1 and the characterization of threshold graphs with at most five distinct Seidel eigenvalues are derived. Also, a class of Seidel integral threshold graphs is obtained. For a connected chain graph G, we study its Seidel characteristic polynomial, Seidel energy, and Seidel cospectral property. We show that 1 is always an eigenvalue of S and all other eigenvalues of S can have a multiplicity at most two. We obtain the multiplicity of the Seidel eigenvalue 1, minimum number of distinct eigenvalues, the eigenvalue bounds, and the lower and upper bounds of the Seidel energy of a chain graph. It is also shown that the energy bounds obtained here work better than the bounds conjectured by Haemers. An important result is that two non-switching equivalent chain graphs may be Seidel cospectral, and we obtain a class of such graphs. Also, the class of Seidel integral chain graphs is shown here. In the context of cographs, we establish that it is possible to link a creation sequence for a particular kind of cograph (we call this sub-class of cograph a mathcalC-graph). Such cographs are constructed from a limited sequence of positive integers. Using that sequence, we can determine the multiplicity of the eigenvalues 0, 1, and inertia of the cograph under investigation. An extended eigenvalue-free interval from (1; 0) to _1 P 2 2 ;1) [ (1; 0) [ (0; 1+ P 2 2 _min _, (where _min _ 1 is the least of all natural numbers in the creation sequence) is obtained for C-graphs. Additionally, we derive an exact formula for the characteristic polynomial. Finally, we investigate the Laplacian eigenvalues and eigenspaces, various connectivity parameters with extremal property and clique number of C-graphs. Finally, we make an attempt to find a connection between algebraic connectivity and clique number

Investigating the Mechanistic Role of PPA2 in Mitochondrial Fission and its Modulation for Oral Cancer Therapeutics

The mitochondrial pyrophosphatase PPA2 is a mitochondrial matrix localized protein known for maintaining mitochondrial function. I found that PPA2 induced mitochondrial fission signaling through the MTP18-DRP1 axis. Interestingly, PPA2 overexpression upregulated mtDNA content and symmetric mitochondrial fission through MFF and DRP1, leading to mitochondrial proliferation. However, during mitochondrial stress following CCCP treatment, PPA2 induced asymmetric mitochondrial fission through FIS1 and DRP1 to segregate damaged mitochondrial parts. Furthermore, PPA2 interacted with MTP18 and induced mitophagy using the C terminal LC3 interacting region (LIR) of MTP18 to clear damaged mitochondria. Furthermore, I found that the expression of PPA2 was significantly increased in OSCC tissue compared to associated normal tissue. PPA2 knockdown inhibited oral cancer cell survival and promoted apoptosis during cisplatin treatment. Moreover, PPA2-mediated cell survival was compromised in mitochondrial fission-deficient conditions, suggesting PPA2 activated mitochondrial fission through the MTP18-DRP1 axis and protected against cisplatin-induced apoptosis. In this connection, therapeutic modulation of mitochondrial fission and mitophagy during cancer progression is an emerging approach to enhance anticancer therapy efficacy. The use of natural compounds as mitophagy modulators is highly encouraging due to their multi-target specificity and low side effects. Here, I explored the anticancer potential of Bacopa monnieri (BM) through the induction of mitochondria fission and mitophagy. I identified that the aqueous fraction of the ethanolic extract of BM (BM-AF) had a potent anticancer potential. BM-AF restricted oral cancer cell survival and promoted PARKIN-mediated mitophagy in oral cancer cells. The in vivo antitumor effect of BM-AF was further validated by the 4NQO- arecoline-induced oral cancer model in C57BL/6J mice. Further detailed mechanistic investigation revealed that Bacopaside-I (BS-I), a saponin from Bacopa monnieri, downregulated the arecoline-induced mitochondrial dysfunction and NLRP3 inflammasome activation in oral cancer cells. Moreover, BS-I induced mitochondrial fission by PPA2-mediated DRP1 activation and triggered PINK1-PARKIN-mediated mitophagy for elimination of the dysfunctional mitochondria to restrict oral cancer initiation and progression

Terrestrial Carbon Cycle and its Feedback at the Regional Scale

Mapping ecosystem carbon across different scales and comparing estimates from various systems is essential, both in its own right and for understanding the increasing exchange of atmospheric carbon dioxide (CO2) between the atmosphere and biosphere. While the global terrestrial carbon sink helps mitigate the accumulation of atmospheric CO2, this process is contingent upon climate and ecosystem factors. The fundamental biophysical mechanisms governing ecosystem-carbon-climate interactions and their feedback mechanisms remain highly uncertain. Despite extensive efforts to track changes in ecosystem dynamics and attribute them to environmental factors using sophisticated data platforms, there is intense debate about whether studying regional carbon budgets can reconcile discrepancies in carbon flux calculations and improve global carbon budget estimates. Significant carbon variability is associated with large uncertainties stemming from Land Use Changes (LUC), resulting in a regional carbon source at seasonal to interannual scales, although without long-term positive or negative feedback. In the face of rapid LUC, continuous monitoring of carbon variability is crucial to understand India's role as a carbon sink in the global budget. Unlike other global regions, limited observational networks in India have hindered efforts to capture dynamics and fluctuations in the Indian carbon budget. However, recurrent Earth observation systems have facilitated monitoring carbon flux variability from diurnal to decadal timescales and from local to global spatial scales, aiding research in understanding ecosystem traits and subsequent carbon variability. Integrating predictive Earth System Models (ESMs) with diverse data streams reveals the sensitivity of carbon fluxes to various global environmental drivers across diverse climate and vegetation gradients. Focusing on understanding India's regional carbon dynamics in recent history, this dissertation employs in-situ, remote sensing, and process-based models to emphasise the interaction of regional carbon dynamics with multiple drivers. Flux variability, in both magnitude and pattern, differs across ecosystems but demonstrates a strong consistency among datasets. Integrating eddy covariance observations with remote sensing data emphasises the importance of synergistic use of multivariate datasets in understanding ecosystem productivity across temporal scales. India's diverse flora results in varying carbon uptake across biomes, with tropical ecosystems serving as dominant carbon storage hubs. However, the regional carbon cycle is reshaped by multiple environmental drivers, subsequently influencing climate patterns. Considering atmospheric aerosols as a hindrance, a remote sensing process-based model, the Carnegie Ames Stanford Approach (CASA), was employed to examine the potential effect of aerosol load on ecosystem productivity across diverse agroclimatic zones of India. Carbon flux sensitivity varies across ecosystems, with pronounced positive and negative feedback effects observed over forest and cropland ecosystems. To explore the complex dynamics of India's carbon uptake under various forcing scenarios over the past century, the Community Earth System Model (CESM) was utilised. This model traces how rising atmospheric CO2 concentrations and climate changes influence India's net land sink. Principal climate drivers were considered to identify their roles in potentially triggering long-term shifts in Indian ecosystem functionality as a carbon sink. Although the analysis indicates India's historical role as a carbon sink, asymmetries in decadal and seasonal trends from the integrated model ensemble suggest the potential for future terrestrial carbon loss, particularly in forest-based ecosystems. Explicit analysis by this research advances our understanding of India's carbon sink dynamics and underscores the sensitivity of carbon uptake to various environmental challenges. It emphasises the urgent need for adaptive strategies in the face of these challenges. Considering the ecosystem-specific sensitivities between carbon uptake and environmental drivers, future efforts incorporating divergent data platforms into process-based models within specific gradients will significantly enhance our understanding and prediction of future carbon uptake at regional and global scales

Study of UV-bright Stars in Galactic Globular Clusters Using Ultraviolet Imaging Telescope (UVIT) Observations

The hot stellar systems of a globular cluster (GC), such as horizontal branch (HB) stars, hot post-HB stars evolving towards asymptotic giant branch (AGB) phase, AGB-manqué stars, post-AGB stars, post-(early) AGB stars, white dwarfs (WDs), blue straggler (BS) stars, and blue-hook (BHk) stars, among others, dominate the ultraviolet (UV) emission of the cluster. UV imaging of GCs enable us to determine the evolutionary status of these hot sources and to study the dynamics of the GCs based on the quantity and nature of such hot stellar systems present in the cluster. We present the study of five Galactic GCs, NGC 4147, NGC 7492, NGC 4590, NGC 5272, and NGC 6205 using UV imaging observations with Ultraviolet Imaging Telescope (UVIT) onboard Indian space observatory satellite AstroSat. The UVIT observations were performed in several far-UV (FUV: 1300−1800 Å) and near-UV (NUV: 2000−3000 Å) filters. Apart from the UV observations, several publicly available archival catalogs of GCs such as Hubble Space Telescope (HST) GC survey, Gaia catalog of GCs, Ground-based photometry of GCs, Pan-STARRS catalog, 2MASS catalog, etc., were also used to get the optical and infra-red counterparts of the UVIT observed cluster member stars. The UV and UV-optical color-magnitude diagrams (CMDs) were constructed using UVIT FUV and NUV filters along with optical Gaia G, HST F606W, and V filters to identify the stellar evolutionary phases of the hot UV-bright sources present in the cluster. We identified a total of 1027 HB stars, 34 post HB stars (a mixture of AGB-manqué, post (early) AGB, and hot post-HB stars evolving towards AGB phase), 55 BS stars, and 48 WDs in the five GCs. The morphology of the observed HB stars in the five GCs was studied. The HB stars observed in far UV filters were found to be spread from blue-HB to extreme-HB regions whereas HB stars observed in near-UV filters were found in red-HB, blue-HB, and extreme-HB regions. The UVIT observed HB stars in NGC 4147 were found in the blue-HB region and belong to the second-generation population. There are two discrete groups among the HB stars of NGC 4147 visible in the BaF2−V versus BaF2 CMD. The empirical gap between the two groups was found to be 500 K with Teff range of 8,000 − 9,500 K for the first subgroup and 10,000 − 11,300 K for the second subgroup. The He abundances of HB stars in three GCs NGC 7492, NGC 5272, and NGC 6205 were estimated by matching the observed and theoretical HB stars, generated using BaSTI-IAC stellar models. The He abundances were found to be in the range of 0.247−0.350, 0.252−0.265, and 0.247−0.310 for NGC 7492, NGC 5272, and NGC 6205, respectively. There are 3 and 31 post-HB stars detected in NGC 5272 and NGC 6205, respectively. The UV-optical CMDs were able to detect only those post-HB stars which have evolved from HB mass (MHB) ≤ 0.55 M⊙. The UV-bright WD population of NGC 5272 and NGC 6205 were studied in this thesis and found that most of the hot WD candidates in NGC 6205 are extremely low mass (ELM) WDs which are evolved from the binary stellar systems in the cluster whereas the hot WD candidates of NGC 5272 are mostly lying on single stellar evolution WDs or high mass WDs cooling sequences. The cluster dynamics of GC NGC 4590 were studied using the normalized radial distribution of the observed BS and HB stars and found that the cluster belongs to Family II and is one of the youngest clusters among dynamically intermediate-age Galactic GCs. The dynamical age of the cluster is calculated using A + parameter and found to be 0.423 ± 0.096 Gyr

Principle and Topology Synthesis of Integrated Single-input Multi-output and Multi-input Single-output DC-DC Converters

Renewable energy sources (RESs) such as Photovoltaic (PV) and wind dominate total renewable power generation. Since both sources are intermittent in nature, effective solutions are needed for reliable operation. However, due to the erratic nature of RESs, a battery and grid are always incorporated with the RES system to maintain an uninterruptable power supply to load and improve system reliability. Conventionally, separate DC-DC converters are connected among RESs and batteries to the DC bus and load. However, using several SISO converters increases the overall system component count, size, and implementation cost. Therefore, this work has introduced a topology synthesis technique to reduce the costs of synthesizing an integrated three-port converter with a reduced component count. The principle of topology synthesis states that an integrated three-port converter can be easily developed from a conventional SISO converter by replacing a diode with a basic cell inclusive of an additional bidirectional port. This three-port converter is compared with the conventional strategy, which employs two separate DC-DC Cuk converters to generate dual-output voltages. The three-port converter can operate in three operating modes: single input dual output (SIDO), dual input single output (DISO), and SISO, depending on the power transfer among the three ports. The MIMO converter controller structure has multiple interacting control loops to maintain the power balance between source and load demand. With multiple control loops, it is challenging to design closed-loop control algorithm for individual output ports without a proper decoupling method. Therefore, this thesis presents a detailed approach by utilizing the state-space averaging method to obtain the converter model under different modes of operation. Then a decoupling network is introduced to allow separate controller designs. The proposed control structure is composed of a decoupling network to address the inevitable cross-coupling effect of multiport converters present due to various interacting control loops. In addition, a PI-Lead compensator is designed to achieve improved steady-state and transient performance in each operating mode of the three-port Cuk Converter (TPCC). Furthermore, an autonomous mode selection (AMS) technique is proposed to achieve a seamless transition between different operating modes. The AMS technique automatically shifts the operating modes of TPCC by comparing the availability of instantaneous power at each port to maintain an uninterruptable power supply to the load. The proposed TPCC uses to interface solar, EV and utility grid. This system comprises two major parts. The first one is TPCC, which is connected to Solar PV generation, Electric vehicles and DC links. The second one is the secondary side of the DC link, which is connected to the utility grid with the help of a single-phase voltage source converter (VSC). This VSC is a bidirectional converter allowing power flow between the grid and TPCC. An ANF-based phase error minimization technique is implemented to improve system reliability during grid synchronization. Moreover, Power sharing among solar, EV and grid effectively handles both grid-connected and islanded modes. The TPCC controller controls the charging of the EV from PV and the grid. Finally, the feasibility and effectiveness of the proposed control algorithm are validated with the help of a laboratory prototype

Understanding The Role of Ac-93253 Iodide in Apoptosis as an Anti-Mycobacterial Response in Macrophages

Recent studies suggest that host defense mechanisms like autophagy, inflammation, oxidative stress and apoptosis in macrophages play a significant role in host defense against intracellular pathogens like viruses, fungi, protozoan, and bacteria, including Mycobacterium tuberculosis (M. tb). It is still unclear if micromolecules inducing host defense mechanisms could be an attractive approach to combat the intracellular burden of M. tb. Hence, the present study has investigated the anti-mycobacterial effect of apoptosis mediated through phenotypic screening of micromolecules. Through MTT and trypan blue exclusion assay, 0.5 μM of Ac-93253 was found to be non-cytotoxic even after 72 h of treatment in phorbol 12-myristate 13-acetate (PMA) differentiated THP-1 (dTHP-1) cells. We have found that Ac-93253 treatment does not affect autophagy regulation, ROI, or RNI generation in uninfected and mycobacteria-infected dTHP-1 cells. At the same time point and same concentration, inflammation was also not affected upon Ac-93253 treatment. Significant regulation in the expression of various pro-apoptotic genes like Bcl-2, Bax, and Bad and the cleaved caspase 3 was observed upon treatment with a non-cytotoxic dose of Ac-93253. Ac-93253 treatment also leads to DNA fragmentation and increased phosphatidylserine accumulation in the plasma membrane's outer leaflet. Further, Ac-93253 also effectively reduced the growth of mycobacteria in infected macrophages, Z-VAD-FMK a broad-range apoptosis inhibitor, significantly brought back the mycobacterial growth in Ac-93253 treated macrophages. Ac-93253 treatment manipulates the mitochondrial membrane potential, CsA a mitochondrial membrane potential stabilizer, substantially inhibits the apoptosis and abrogates the anti-mycobacterial effect of Ac-93253. These findings suggest apoptosis may be the probable effector response through which Ac-93253 manifests its anti-mycobacterial property

Effect of Different Heat Treatment Procedures on Mechanical Properties and Wear Behavior of Ductile Cast Iron

The Ductile Cast Iron (also known as Nodular or Spheroidal Graphite Iron) was first manufactured in 1948. It came into being as a results of scientist’s effort to develop a particular type of cast iron which can be preferred to malleable cast iron. While malleable cast iron can be formed by a lengthy annealing process (known as malleabilization) of white cast iron, the ductile cast iron can be manufactured simply by adding some nodularizing agents like Mg or Ce (or both) into the liquid melt of gray cast iron. Due to the absence of any heat-treatment schedule of long duration, the production cost of ductile or spheroidal graphite (S.G) iron is much less than that of malleable iron. So the former is preferred to the latter even if the both are equal to each other as far as industrial use is concerned. The use of ductile (or nodular or S.G.) iron has been increasing day by day after its discovery in 1948. It is widely used as the material for windmill. Now it has completely replaced galvanized iron as the material for the water-supply pipes. Now research works are being conducted to examine whether this material can be used for the container for nuclear fuel waste. It has been found that S.G. Iron can be used as the material for the casks used for the transportation of the nuclear fuel wastes. As a result of all these developments extensive works are now being performed for the property development in the ductile cast iron. This can be done mainly by addition of alloying elements or by various heat treatment techniques. In this work the effect of different heat-treatment techniques on the microstructure and mechanical properties of ductile iron has been studied. A special importance has been given on the use of ductile cast iron as a material for the container of nuclear fuel wastes. In the current work, DCI or spheroidal graphite (SG) cast iron samples of four different grades (namely, SG1, SG2, SG3, and SG4) having carbon equivalent varies from 4.12% - 4.36%, were subjected to different types of heat treatment processes such as annealing, normalizing, quenching & tempering (Q&T), austempering and inter-critical austenitization (ICA) to develop dual matrix structure (DMS). The first objective is to study the microstructural features of as-cast and heat-treated samples. This was done by using an optical microscope (OM), transmission electron microscope, and X-ray diffraction (XRD) technique. From the results, it has been identified that each grade of DCI has graphite spheroids embedded in ferritic matrix in its as-received state. The nodules count in the graphite spheroids varies from 20-34 nodules/unit area, and they are Type-I (completely spheroids) nodules with a nodularity greater than 93%. Si addition increases the ferrite volume percentage, while the concentration of Mg, Cu, Si, and Ce are found to raise nodules' quantity and nodularity. With a graphite nodule incorporated in each matrix, normalizing, Q&T, and austempering heat treatments obtained pearlitic, ferritic, tempered martensitic, and coarse upper bainitic matrix, respectively. On the other hand, the as-cast ferrite matrix is transformed into a ferrite + martensite matrix after undergoing ICA heat treatment followed by quenching. Except for annealing, the greater cooling rate during the consequent quenching stages for all heat treatments increases the number of nodules in the matrix by restricting the transfer of carbon from the austenite to nearby graphite nodules. The second objective is to study different mechanical properties like hardness, uniaxial tension, compressive, and impact properties of differently heat treated specimens. The results show that greater hardness readings are obtained for Q&T, followed by austempering and normalizing for all grades of DCI specimens due to hard phases like martensite, bainite, and pearlite in their microstructures. The lower hardness values are obtained for annealed samples due to the existence of soft phases like ferrite for all grades of DCI samples. On the other hand, the optimum hardness values were obtained for all grades of ICA samples due to the existence of dual phases (i.e., soft ferrite and hard martensite) in its microstructures. The uniaxial tension tests were carried out at different strain rates. From the tensile data, it has been identified that strength decrease and ductility increase with the increase in the strain rate and vice-versa. The higher strength and lower elongation are obtained for Q&T and austempered specimens, the lower strength and higher elongation are obtained for the annealed sample, and optimum strength and elongation were obtained for the ICA sample. The tensile testing exhibits a substantial increase in texture intensity for both annealing and ICA specimens due to significant plastic deformation. On the other hand, the increase in texture intensity is less in the austempered and Q&T samples since it resists the tensile deformation by hard phases. The compression properties followed a similar trend like tensile properties. The bulk texture of deformed compressed samples shows that the high intensity ζ--fiber is formed due to increased plastic deformation of the annealed specimen. However, because of the less plastic deformation, less intensity of ζ-fiber combined with the formation of ϒ -fiber has been observed in the austempered and ICA samples. From the impact test results, it has been found that though, the annealed specimens possess the highest impact energy value at higher temperatures, their impact strength falls rapidly below 0oC. Moreover, even at higher x temperatures, the impact strength of the ICA sample is near that of annealed specimens and good at sub-zero temperatures. The last objective is the study of wear behavior. The heat-treated DCI samples were tested under a ball-on-plate type tribometer to study the wear behavior. The Taguchi optimization technique (L16) was initially applied to evaluate the influence of different process variables (load, time, heat treatment, and grade) during the ball-on-plate wear test. Meanwhile, the analysis of variance (ANOVA) method was adopted to know the significance of aforesaid process variables. ANOVA results confirms that the heat-treatment process has the highest significance (54.76%) within all process variables. Among heat-treated specimens, austempered samples have outstanding wear resistance, while the ICA samples have lower wear resistance. In addition, overall utility values have been evaluated using individual utility values of weight loss and hardness. The obtained overall utility value gives the optimum combination for achieving higher wear resistance and hardness. Additionally, the morphology of wear surfaces was examined in a scanning electron microscope, and the micrographs confirm the existence of inferior surfaces in terms of abrasive wear, adhesive wear, particle pullout, and delaminated sheets on the wear track. Enrichment of oxygen element has been observed on the worn path through energy-dispersive spectroscopy. XRD analysis confirms the existence of different compounds like iron and silicon oxides on the wear track surface which may improve its hardness

Wavelets and related Functions on Cantor Dyadic Group and Vilenkin group

The purpose of our work is to study properties of orthonormal wavelets, and the related concepts of frame wavelets and Riesz wavelets, for both Cantor dyadic group and Vilenkin group. At first, we have given the theory of wavelet sets. We have characterized wavelet sets for Cantor dyadic group. All the wavelets originating from wavelet sets are not necessarily associated with a multiresolution analysis (MRA). We have also established relation between wavelets obtained from MRA and wavelets determined by wavelet sets. Scaling and generalized scaling sets provide wavelet sets and hence wavelets. We have given characterization of scaling sets and its generalized version along with relevant examples for Cantor dyadic group. Further, we have studied properties of generalized scaling sets, and relation between wavelet sets and generalized scaling sets. Results related to these sets are also given for the Vilenkin group. Frame multiresolution analysis (FMRA) is an extension of the concept of MRA, and can be used to generate frames. By using properties of shift invariant spaces, relation between FMRA and MRA is established. Further, in a particular case, conditions are given for the existence of frame wavelets associated with FMRA. For Cantor dyadic group generalizations of lowpass filters and scaling functions are introduced, and existence of generalized Parseval frame wavelets is proved. At the end, association between MRA and Riesz wavelets is given along with the construction of frame and Riesz multiwavelets

Investigation of Potential piRNA-mediated Regulation of Oncogenicity and Chemoresistance Imparted by FDFT1 in the pathophysiology of Tongue Squamous Cell Carcinoma

Piwi-interacting RNAs (piRNAs) are key regulators of biological processes that mediate gene regulations at various levels. The abnormal expression of piRNAs is involved in pathophysiological diseases, such as cancer. However, its role in tongue squamous cell carcinoma (TSCC), a highly malignant carcinoma originating from tongue squamous epithelium, has not yet been elucidated. Therefore, in the current thesis, we first investigated the presence of PIWILs and piRNAs in TSCC cell lines and found that 407 piRNAs are dysregulated. Among these, we found only 46 piRNAs target 158 differentially expressed genes, of which only 5 genes are enriched in TSCC significantly. Then, we validated the reciprocal expression pattern among the target–piRNA pairs through qRT-PCR, from which we selected FDFT1, the only upregulated target that could be a potential oncogene. To decode mechanistic insights into the functions of FDFT1, we executed several molecular biology assays in SCC-9 and H357 TSCC cell lines in vitro. We overexpressed FDFT1 in TSCC cells and found an increase in viability, proliferation, migration, and ROS generation, indicating its oncogenic nature. We found overexpression of piR-39980, a key regulator in various cancers, and downregulated in TSCC inhibit FDFT1 as its target, which was confirmed from the luciferase reporter assay. To explore the effect of piR-39980 in TSCC, we overexpressed and silenced it in TSCC. We found that its overexpression could attenuate the oncogenicity of FDFT1 and inhibit cell viability, proliferation, migration, and ROS generation by suppressing the EIF3H/HIF1α axis, inducing hypoxia and causing p53-induced apoptosis and its silencing, showing the reverse. This tumor-suppressive nature of piR-39980 and the oncogenic nature of FDFT1 encouraged us to study whether these modulate the chemosensitivity of Doxorubicin in TSCC, an obstinate issue in chemotherapy. Interestingly, we found piR-39980 increases the sensitivity of Doxorubicin in TSCC cells by increasing its accumulation synergistically by deregulation of FDFT1, CYPOR, and EIF3H/HIF1α axis. In summary, these findings build the possibility of piR-39980 as a novel RNA-based therapeutic agent and FDFT1 as a therapeutic target to treat TSCC and overcome chemoresistance, which needs further investigation