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

Cognitive State Classification using Multi-modal Features

Recently, classification of cognitive states has received considerable attention from several disciplines such as psychology, cognitive science and medical engineering, etc. The multi-modal features extracted from gait and EEG data play an important role for analysing and understanding different types of cognitive states. The existing gait analysis systems are very expensive with the utilisation of high-end gold standard cameras namely Qualisys, OptiTrack, Vicon etc. A low-cost experimental setup for gait analysis is proposed in this thesis. This thesis provides a unique and innovative method for classification of cognitive state using multi-modal features. The dynamics of human gait is studied with anatomical knowledge of the human body for understanding the cognitive states. We apply different vision-based and sensor-based approaches for classifying cognitive states using multi-modal features. Camera calibration is an important step for measuring an instrument’s accuracy with its parameters. A multi-Kinect setup is created due to the limitation of single Kinect measurement range for capturing complete movements of a person. We apply fusion techniques for acquiring synchronized data captured from multiple calibrated Kinects. Two fusion methods namely Kalman filtering and a modified Set-Membership filtering are compared for estimating states of discrete time linear systems. Both the fusion techniques are tested on overground and treadmill data. The outcomes are validated with the gold standard cameras. The proposed Set-Membership filtering approach is compared quantitatively with state-of-the-art techniques. Another study is done to determine the accuracy and reliability of gait features. A novel approach for human detection and tracking is proposed which involves gait feature learning principles from depth and RGB videos. We apply various machine and deep learning modes on depth-based features. The feasibility study of gait signatures is performed using various statistical methods as well for validation with benchmark dataset. A novel event driven environment is created for analysis of cognitive states, using external stimuli through capturing EEG data with 14-channel Emotiv neuro-headset. We extract Gammatone Cepstrum Coefficients (GTCC) features from ambulatory EEG signals. Higher feature importance analysis-based scores are obtained for GTCC features indicating their discriminative ability. Various classification models are employed to achieve promising accuracy on proposed features. The entire approach is validated with benchmark SEED-IV dataset as well. Understanding the human psychology and classification of the cognitive states via multi-modal features is a new area of research in the field of cognitive science. A novel approach using multi-modal feature analysis is proposed for classification of cognitive states. The advantage of a multi-modal system is to provide adequate and diversified data to ensure data reliability for classification. Initially, the association between cognitive states and types of gait is estimated using Pearson’s Correlation Coefficient, Analysis of variance (ANOVA) and Support Vector Machine (SVM) classifier. We propose temporal and non-temporal Bayesian network-based probabilistic models for estimating cognitive states. We use different techniques such as Gaussian Mixture Modelling-Expectation Maximization (GMM-EM), k-Nearest Neighbors (k-NN) and Principal Component Analysis (PCA) to calculate the input probabilities for the Dynamic Bayesian Network (DBN) model. Furthermore, we use deep learning classification models such as Gated Recurrent Units (GRU) and Convolutional Neural Networks (CNN) for classifying the cognitive states. Standard statistical tests and comparative analysis with state-of-the-art research are performed on acquired dataset to validate the experimental results

Surface Modification of Ti-6Al-4V Alloy by Depositing MMC Coating with Variant of Matrix Phases through TIG Cladding Method

Ti-6Al-4V alloy has numerous applications in the field of aircraft, chemical, marine, and biomedical industries because of its remarkable properties, like, high strength-to-weight ratio, elevated melting temperature, excellent corrosion resistance, and biocompatibility. Nevertheless, its poor wear resistance, restrains its scope of application, when it is working under a wear and friction environment. Depositing a hard and wear resistance coating through Tungsten Inert Gas (TIG) cladding route was found as a suitable approach to enhance the wear resistance of Ti-6Al-4V alloy. TiC as a reinforcement ceramic, widely used in composite coating, and proficiently improve the hardness and wear resistance of a metallic component, even at elevated temperature. Present research emphasized on the development of TiC reinforced hard and wear resistance composite coatings on Ti-6Al-4V alloy, by using a variety of matrix phases through TIG cladding route. Primarily, TiC-Co coating was fabricated on a Ti-6Al-4V alloy plate using TiC/Co powder blend. Co as a matrix phase with TiC reinforcement enhanced the interfacial bonding and accelerated the anti-oxidation and abrasive wear resistance of the composite coating. The effect of processing current, and stand-off-distance (SOD) during TIG cladding on the quality and performance of the coating was also analyzed. It was revealed that the TiC-Co composite coating developed with higher SOD (6 mm) and lower current (120 A) exhibited higher hardness and wear resistance against different counter rotating discs. Further, to increase the microstructural uniformity of the composite coating nano-Y2O3 was added to the precursor powder, and accordingly TiC-Co-Y2O3 cladding was developed on the Ti-6Al 4V alloy by the TIG cladding method. With the addition of nano-Y2O3, the melting efficiency of the precursor augmented, which completely melted the TiC particles and transformed them into elongated dendrites during solidification. The addition of nano-Y2O3 effectively refined the grain structure of the clad material, and improved the micro-hardness, fracture toughness, and ductility of the coating. Almost, a four times reduction in the wear value was recorded for TiC-Co-2%Y2O3 coating as compared to TiC-Co coating. In the succeeding work, TiC reinforced composite coating with NiCoCrFeTi high entropy alloy (HEA) as matrix phase was developed on Ti-6Al-4V alloy. The microstructural analysis of the coating revealed that, along with dendritic TiC, the presence of HEA matrix, augmented the wear resistance of the coating enormously, and shows almost 7.5 times lower wear value as compared to the uncoated Ti-6Al-4V alloy. Through EBSD, XRD, and thermodynamic analysis, the formation of BCC/FCC phases shows the possibility of solid solution/intermetallic in the coating. Additionally, large area TiC-NiCoCrFeTi HEA composite coating was also fabricated through side-by-side deposition of the consecutive clad tracks. A least discrepancy in the thickness and hardness of the coating was witnessed for using 50% overlapping to produce the large area cladding. The corrosion test performed on the TiC-NiCoCrFeTi HEA coating showed its adequate corrosion resistance in 3.5% NaCl solution

The Molecular Mechanism of Nanoparticle-Mediated Toxicity, Regeneration and Wound Healing in Drosophila Melanogaster

The development of nanoparticles (NPs) in nanotechnology has emerged as a potential target for studying applied science and technology. NPs are used in various sectors, such as food industries, cosmetics, biomedical, drug design, and drug delivery. NPs are classified as inorganic or organic, carbon or polymeric or ceramic-based, and metal or metal oxides. NPs showed both beneficial and harmful effects when exposed to an organism. Due to the worldwide applications of NPs, humans and animals are significantly exposed. The toxicity of NPs may depend on the nanomaterial's shape, size, and surface area. NPs showed cytotoxic and genotoxic and may alter the physiology and behaviour of the organism by altering various signaling pathways. Metal, metal oxide and polymeric NPs were used extensively in food packaging due to their antimicrobial and antifungal activities. However, when we consume these foods, these NPs can easily enter our body and causes many symptoms and disease. Many studies have reported the toxicity of NPs using various in vitro and in vivo models. But, the studies failed to underline the toxicity, safe, and appropriate applications of NPs simultaneously. Therefore, the current study aims to scrutinise the effect and molecular mechanism of NPs mediated toxicity and its application in regeneration and wound healing by using Drosophila melanogaster as a model organism. The first objective aims to investigate the effects of Al O nanoparticles (AlNPs) as potential mutagen and teratogen and their toxicity mechanism. AINPS were fed orally along with standard food and were found to alter Drosophila’s growth, development, and behavior. It was observed that both larvae and adult flies showed high ROS formation and neuronal disorder by altering the antioxidant enzymes. AINPs showed high toxicity to gut cells, resulting in DNA damage, micronuclei formation, and mitochondria depletion. The second objective elucidates the toxicity of polymeric Fe3O4-GG nanocomposite (GGNCS) and its application in nanomedicine. After feeding GGNCS, the toxicity profile was checked and found negligible cytotoxic effects according to their concentrations. GGNCS were able to reduce flyweight, glucose, and triglyceride contents. The behavioural abnormalities were also observed on treated larvae and files. Alteration of antioxidant enzymes in treatment showed ROS generation in a concentration-dependent manner. The third objective is to investigate the toxicity and role of platinum nanoparticles (PtNPs) for wound healing and regeneration application in nanomedicine. Investigation showed that PtNPs have a very negligible amount of cytotoxic effect. But, PtNPs can scavenge the ROS by mimicking an antioxidant enzyme and protecting the cells from oxidative stress. PtNPs also interact with hemolymph and help in angiogenesis. It was also observed that PtNPs help in mitochondrial biogenesis. Further, PtNPs were also applied in wound healing and observed that they fastened the wound healing and tissue regeneration process compared to the non-treatment. Together, all the studies revealed the toxic effect and the safe application of metal oxide (i.e., AlNPs), polymeric (i.e., GGNCs), and metal (i.e., PtNPs) NPs

Loading Response of Laminated CFRP Composites with Hole cutout: Geometrical Design Effect on Material Strength and Failure Mechanism

In recent decades, CFRP laminates have become popular material among design engineers due to their high strength and stiffness-to-weight ratio, corrosion resistance, thermal stability and chemical inertness. It is being exploited in many engineering applications like automobile, aerospace, civil, marine, commodity, sports, etc. As a further matter, CFRP is typically a brittle material and catastrophically fails without sufficient warning. The catastrophic failure of CFRP is usually compensated by a conservative design limit which hinders exploiting outstanding materials’ mechanical properties. The design of the component must be compatible with the material and must be able to resist specific loading condition. Since welding of CFRP components are not possible therefore design of open hole in the component is inevitable; it is made to incorporate pins, rivets or bolts for assembly of the components into the final structure. Moreover, holes or cutouts in the component are also used to lighten the structure and fulfill some functional requirements such as the passage of electrical and fuel lines, accommodation of doors and windows. Thus, understanding material response due to the design of hole/cutout is of utmost importance. The present study demonstrates the effect of hole, hole shape, hole size and stacking sequence on laminated CFRP components under two different loading condition. Additionally, detailed failure mechanism and strength prediction models have also been assessed. The study started through experimental investigation on the effect of stacking sequence, hole size, and hole shape on the tensile strength of CFRP laminate. Reduction in Open Hole Tensile (OHT) strength is observed when stacking sequence is changed from [0]8 to [0/90]2s and when the hole size is increased. However, OHT strength is noticed to get increased when hole shape is changed from circular to square. Laminates containing square shaped hole demonstrate less sensitivity towards tensile strength and show negligible effect of stacking sequences on the normalized strength than the circular hole. A further testing program was performed on CFRP laminates under flexural loading. Flexural and Open Hole Flexural (OHF) test of CFRP as a function of stacking sequences report that the [0]8 laminates have the highest flexural and open hole flexural strength. During the evaluation of strength retention value, [02/902]s laminate is found to be best among all investigated stacking sequences. [02/902]s and [90/0]2s is found best for better isotropy of open hole flexural strength among the laminates having first ply at 0◦ and 90◦, respectively. Further, a comparative analysis has been done on CFRP laminate to understand the design aspect of holes/cutouts under the tensile and flexural loading. Tensile loading is found to be more detrimental than flexural loading for composite laminate with hole. SEM and optical micrographs have been analyzed to perceive the failure mechanisms of laminates under two different loading conditions. Mode I dominated delamination and mode II dominated delamination are found to be prevalent in OHT (open hole tensile) and OHF (open hole flexural) failure, respectively. The results of the testing program and strength prediction models were compared and assessed through deterministic analysis. Longitudinal laminates show some discrepancy between predicted data and experimental data. However, crossply laminates are found to approach congruence with experimental data. In deterministic analysis, the failure pattern of each laminate system has been studied. The microscopic examination of fractured samples has also been done to study failure mechanisms. Both longitudinal and crossply laminates show a brittle fracture, but the splitting in longitudinallaminates accorded a hint of gradual failure because laminates continue to bear load; Nevertheless, laminates suddenly lead to lateral brittle fracture

Dynamics of Outward Foreign Direct Investment from BRICS: A Study of Home and Host Country Effects

Capital is considered as an asset which is used to supply continuing production of goods and services for obtaining profits, and it helps to improve the economic conditions of a developing nation. The role of foreign capital is essential for economic development as it enlarges the competitiveness of the domestic market through transfer of technology, improving infrastructure, reducing unemployment, and involving in more productive activities. The “Foreign Direct Investment” (FDI) is a part of foreign capital which acts as a direct investment made by outsiders in the domestic market. It mainly considers international business operation in home countries. The objective of the research is to investigate the human and economic development in emerging countries. Also, the study will analyse the economic variables that determine the site choices of emerging countries for Outward Foreign Direct Investment (OFDI). Traditional interpretations about FDI are being challenged because of the sustained growth of OFDI in developing and emerging economies all around beginning of the twentieth century. The old theories are based on the experiences of large multinationals from developed and advanced economies and are not applicable to developing and emerging markets. As a result of this issue, there is disagreement about whether the existing theoretical concept of FDI, such as the International Organizational Framework, the Monopolies Advantages Theory, the Internalization Theory, and the Ownership-Location-Internalization (OLI) Concept, should be substituted by current models, maintained the same, or extended and modified to better match the setting of developing and emerging economies. Earlier studies, inspired by the troubling discussion, evaluated the explanatory capacity of traditional-OLI theory and innovative FDI theories Product cycle theory. However, such a strategy is revealed to be theoretically constrained (Buckley et al., 2007). To make traditional FDI theories more relevant for describing the quantity and type of outbound FDI from developing markets, the home country influence in contextual components, especially institutional environment is more important (Dunning and Lundan, 2008; Peng et al., 2008). The home country's macroeconomic and institutional environment, known as "L" advantages, can be used directly to enable OFDI flows. Indirectly, features of the home nation have a significant influence on determining the kind of "O" advantages that its firms have, which defines their capacity to invest overseas (Narula & Kodiyat, 2016). The current study will provide a conceptual framework that combines traditional economic considerations and identifies institutional distance. This study will restrict the sample areas for panel analysis by focusing on BRICS and India from 1990 to 2021 and 2012 to 2021, respectively. The research investigates four objectives to see the dynamic influence of OFDI in the BRICS. The initial goal is to explore the overall performance of OFDI as well as the changing pattern of OFDI. The primary objective is to investigate the achievement of OFDI as well as its changing pattern. The 2nd objective is investigated and explored the direct influence of outward FDI on both the host and the home nation. First and second objectives (2a) were addressed in the research, and the study followed an advanced methodology throughout the first chapter. In the first portion, the first chapter delivered an outline of the major trends and patterns of BRICS OFDI. Using five home countries as case studies, the second objective (2a) is to investigate the influence of macroeconomic performance on the amount of outward foreign direct investment (FDI) in home nations from 1990 to 2019. Using both fundamental and sophisticated methods, the study's findings conclude that most macroeconomic factors are relevant and positively influence outward FDI. Financial development is inversely connected with OFDI, showing that the countries' financial development does not stimulate external FDI, resulting in the countries' development deteriorating. The third chapter explores the influence of informal institutional distance and locational choice on home and host nations as it belongs to the second purpose of this research (2b). The paper uses the BRICS as a sample of investment home countries to examine the institutional effectiveness of OFDI in twenty host countries from 1990 to 2020. To determine the objective, the study used OFDI flows as a dependent variable acquired from UNCTAD and various independent factors for empirical analysis. The study employed a basic and augmented gravity model in which the traditional gravity components are positive and important, indicating that BRICS locational option is favourable. The augmented gravity approach discovered that the regulatory institutional distance (RID) that exists between home nations and selected host countries tends to block OFDI. On the other hand, normative and cognitive institutional distance frequently favour OFDI. The third goal of the research is to look at the linkage between technical innovation, outward FDI, and human capital in the BRICS from 1990 to 2020. This study employs Fixed-effects Regression and threshold Regression for static analysis, and FMOLS and 3SLS for robust results in the empirical portion. The study's outcomes reveal that all the determinants have long-term stable correlations. BRICS FDI has been found to be significantly related to home nation innovation performance, human resources, GDP per capita, and research intensity. Yet, the opposite would not be true for our model. Lastly, the fourth objective of the research investigates the overall performance of the economic variables of outward FDI analysis from India on both the country and firm levels in chapter five. The study investigates two types of analysis: country-level (level-1) and firm-level (level-2). After a diagnosis check, the research performs an augmented gravity analysis, where POLS and F-GLS results have little effect on the variables. The study used PPML to reduce heterogeneity and found that traditional gravity variables are relevant, showing that locational qualities of the host nation attract Indian OFDI. The PPML also discovered that institutional traits, such as regulatory and cognitive institutional distance, attract foreign investment. Nonetheless, there were no particularly noteworthy results from the cultural gap. Hence, language and cultural limitations likely explain India's low FDI to its top seven host nations. Level 2 of the study, which included 21 manufacturing firms, discovered that overall firm-level OFDI is increasing at a rather slow rate. The robust GMM findings indicated that profit and income are higher for Indian OFDI, but company size and foreign participation are unaffected

Mathematical Analysis of Some Boundary Layer Flows

The research presented in this thesis focuses on the analysis of some boundary layer flows. This work is divided into three parts, each corresponding to a different flow scenario. The first part regards the mathematical formulation of the boundary layer equations for two- or three-dimensional flow, which are the highly nonlinear partial differential equations (PDEs) of parabolic type. Moreover, the PDEs are converted into nonlinear ordinary differential equations (ODEs) using suitable similarity variables. It is worth recommending that the ODE boundary value problems (BVPs) governing these flow are intrinsic nonlinear, which becomes difficult to find an analytical solution than numerical results. The reduced boundary value problem is then analyzed in the subsequent parts of this thesis to understand the flow behaviours. Previous works were mainly focused on numerical simulations, and several conjectures regarding the existence and the behaviour of the solutions are discussed from the computational results. The ambition of this work is to review these conjectures mathematically. The second and major part contains the existence of a solution to the BVPs for the entire appropriate the physical parameters values. Uniqueness results are also presented for some (but not all) values of the parameters. It is to be mentioned here that the solutions are concave or convex for different parameter values, and in some cases, the differences in proofs and results may be significant. Both the cases are discussed thoroughly. Moreover, the last part contains the numerical results of the governing BVPs. The numerical results elucidate through table and graphs. In the limiting cases, the results are in great agreement with previously reported solutions in the literature. To demonstrate detail physical aspects of the flow domain, the velocity profiles and streamlines are presented graphically for governing parameters, and the results are discussed in detail

Development of Anti-Corrosion Coatings for Copper from Electrochemically Exfoliated Few Layered Graphene Nano-Sheets

“Corrosion” is an age-old phenomenon that has crucially affected humanity especially the industrial sector causing substantial economic losses and also compromising safety. In order to counteract this “destructive” force, many mechanisms have been developed out of which “coatings” are a reliable method. Deposition of graphene on copper has found use in electronics, energy storage, and catalysis, among other fields due to the outstanding properties of graphene coupled with copper's strong thermal and electrical conductivity. The current work revolves around the idea of using graphene as a corrosion preventor owing to its exceptional mechanical, electrical, and barrier properties. The concept of electrophoretic deposition has been utilized to coat graphene nanosheets onto copper substrates and the latter has been tested for corrosion preventive behaviour. In present study, few layer graphene nanosheets (FLGNs) were synthesized from pyrolytic graphite by using four different molarities of Na2SO4 (sodium sulphate) aqueous solution in concentrations of 0.5 M, 1.0 M, 1.5 M and 2.0 M via electrochemical exfoliation methodology. FLGNs were also exfoliated from four different acid-based solutions of 1 M concentration (sulphuric, perchloric, nitric and combination of the three). The obtained FLGNs were characterised by XRD spectroscopy, Raman spectroscopy, UV spectroscopy, FTIR spectroscopy, XPS spectroscopy, DLS, SEM, TEM and AFM. X-ray diffraction and Raman is used to investigate structural characteristics and crystal structure arrangement. (002) lattice plane corresponding to basal plane of graphene is identified at around 26° (2θ angle). Raman spectroscopy depicts an increase in disordered value of the FLGNs which may be due to exfoliative activity and surface functionalization. UV, FTIR and XPS confirm the presence of functional groups attached to graphene network which however was not present in large amounts in the case of FLGNs derived from Na2SO4 solutions. Acid based FLGNs on the other hand showed a higher oxygen content pointing out to the presence of hydroxyl and carbonyl groups. The energy transitions occurring with respect to π-π* and n-π* orbitals are detected through the absorbance spectra in UV-visible spectroscopy. A wrinkled, folded sheet type of structure is visible in SEM which appears arranged in a stacked manner. TEM depicts transparent and semi-transparent morphologies which gives idea about the number of layers. AFM supplements the morphological results by giving inputs about the lateral dimensions and approximate number of layers. The obtained FLGNs were dispersed in double distilled water and ultrasonicated for around 3 – 4 hours to get a homogenous solution. This solution is then used for electrophoretic deposition with copper substrates as anode and graphite rod as cathode. The samples are coated through a iterative process consisting of different potentials, time and layers. A set of coatings was made to undergo heat treatment (130°C for 1 hour) to analyse the effects. Methyl violet (surfactant) was dispersed with graphene for creating another set of coatings to view the effects of added environment. The coatings were observed under optical microscope and SEM for morphological characterization along with EDS. SEM micrographs show layer-upon-layer deposition of graphene on copper substrate. The coatings were subjected to scratch tests to determine their adhesion strength and complement the electrochemical measurements. Thereafter, the coatings underwent potentiodynamic polarization and electrochemical impedance spectroscopy tests to assess their corrosion characteristics and coating behaviour. Results from polarisation and impedance testing demonstrated that graphene was an effective corrosion barrier compared to an uncoated substrate. The authors also made an effort to comprehend how the coating's thickness impacts the substrate and the latter's resistance to damage. It was discovered that 2-layer coatings provided the best resistance. In conclusion, graphene's use for corrosion protection seems warranted, however further research is obviously necessary

Development of Hydroxyapatite Coated Titanium Alloy with Improved Corrosion Resistance and Biocompatibility for Bone Implant

The ability of a material to carry out its intended task by extending desirable functionalities after a medical intervention being performed without getting rejected by the host is known as biocompatibility. The basic criteria for a material to be considered as an implant material is its biocompatibility (cytocompatibility, hemocompatibility, non-immunogenicity), higher fatigue and shear strength, and corrosion resistance. Usually, metallic biomaterials possess appreciable mechanical strength and are nontoxic, but they suffer from inherent shortcomings such as bioinertness and corrosive wear. These problems can be dealt by adopting various surface modification techniques to alter their surface topography. Hydroxyapatite (HAP) is one of such popular coating materials for metallic implants. However, the most undesirable problem with HAP coatings is their lower adhesion to the implant. The resistance to bending, chipping and delamination during the medical procedure and post operative activities are also serious concerns associated with the HAP based coatings. In the present study, the surface morphology of implant grade Ti6Al4V alloy sheets was successfully altered by applying bioactive hydroxyapatite (HAP) coating. This was attempted mainly because HAP possesses the closest structural analogy to human bone and allows chemical functionalization for tailoring its properties. The coating was achieved by two approaches namely, biomimetic mineralization and microwave irradiation. The microwave irradiation process also yielded cationic doped HAP coating by incorporating Niobium (Nb) as dopants in HAP. Three major input parameters viz. irradiation power (W), doping % of Nb and time of exposure (min) were considered for the experimental runs and targeted biological responses such as hemolysis %, clotting time and protein adsorption from blood plasma were optimized using Grey-Taguchi analysis. The sample coated with this optimal factor setting was further used for other assays. Additionally, an attempt was made to co-dope the HAP with Strontium (Sr) along with Nb via microwave irradiation and these samples were also assessed for their physical and biological properties. The surface characterizations revealed that both approaches yielded homogeneous surfaces free from flaws. However, it could be observed that the morphology of the HAP particles altered after the cationic doping in case of microwave assisted coating. The characteristic peaks of HAP could be confirmed in the crystallographic studies performed on the coated samples. After performing various assays, it was observed that both the treatments rendered higher hardness to the substrate, but an insignificant increase of surface roughness was present. However, the wettability of the Ti6Al4V sheet was considerably increased after the coating was applied which could facilitate better host-implant interaction. Potentiodynamic polarization studies revealed that the barrier action offered by the HAP coating had significantly reduced electrochemical corrosion in the form of ionic dissolution. The treated samples showed lesser hemolysis as compared to untreated sample and did not induce clotting of the blood, making them more hemocompatible. The protein adsorption capacity was enhanced by the application of coating, which also significantly enhanced biocompatibility. Reduced cytotoxicity was also evident from cell culture assay and the treated surface also prevented bacterial growth. The cell viability post doping found to have increased by more than 30%. Moreover, there was no evidence of cytotoxic effect of either Sr or Nb on human cells as confirmed from the cell viability assay. The co-doping found to help cell proliferation. So, it can be concluded that the incorporation of metallic ions like Sr and Nb in HAP coating can protect the implant surface from the body fluid-induced wearing as well as bacterial infection and thus, prolong its life. Therefore, microwave-assisted coating can be considered as a one-step solution for simultaneous synthesis and deposition of reinforced HAP coating on metallic implants

Experimental Investigation of LHR Engine Run on an Antioxidant-Doped Biodiesel-Diesel Blend

Biodiesel is derived from plant oils, animal fat, and algae by the esterification/transesterification process. It can be either used directly or in a blended form with diesel in compression ignition (CI) engines. The important merits of biodiesel when used as an alternate fuel in CI engines are (i) it does not produce SOx emissions, (ii) hydrocarbon (HC), carbon monoxide (CO), and smoke emissions are lower. However, there are a few important technical challenges found with the utilization of biodiesel in CI engines, which include (i) lower engine performance, (ii) higher oxides of nitrogen (NOx) emissions, and (iii) oxidation stability. The brake thermal efficiency (BTE) of the engine is slightly reduced and brake-specific fuel consumption (BSFC) is higher in the biodiesel-fueled diesel engine. This research work is aimed at simultaneously improving efficiency and reducing NOx emissions of a biodiesel-diesel blend run direct injection (DI) diesel engine. For this purpose, a conventional DI diesel engine is made to run in a low heat rejection (LHR) mode to inhibit heat loss to improve the thermal efficiency of the engine. The biodiesel-diesel blend considered in this study is JME20 which contains 20% Jatropha methyl ester (JME) and 80% diesel on a volume basis. On the other hand, an antioxidant is doped in the biodiesel-diesel blend to reduce NOx emissions. Initially, thermal and structural analyses are carried out considering two different TBC pistons. Thermal barrier coating (TBC) comprising Yttria stabilized zirconia (YSZ), and YSZ + Cerium oxide (CeO2) (85%YSZ+15%CeO2) is applied on an aluminum alloy piston. Three different thicknesses of the topcoat of materials for YSZ and YSZ+CeO2 coating viz. 0.3 mm, 0.6 mm, and 0.9 mm are chosen. SOLIDWORKS software is used to draw pistons and different thicknesses of layers (top coatings). ANSYS software is used for performing structural and thermal analyses on the piston surface. The YSZ+CeO2-coated piston gives better results in thermal and structural analysis when compared to the YSZ-coated piston. Therefore, the YSZ+CeO2-coated piston is used to form an LHR engine for experimental investigations that are further carried out in this research work. Six experimental works are carried out to study the combined effect of running a DI diesel engine run in the LHR mode fueled with an antioxidant-doped JME20. For this purpose, a single cylinder, four-stroke DI developing the power of 4.4 kW at 1500 rpm is converted to LHR mode by coating the piston with YSZ+CeO2. Initially, the engine is run on diesel and JME20 to obtain baseline data. The peak cylinder pressure and heat release rate are increased by 1.8% and 2.2%, respectively, for the YSZ+CeO2-coated piston-fitted engine compared to the uncoated piston-fitted engine run on JME20. The ignition delay and combustion duration are improved by 16.8% and 3.5%, respectively, at full load when compared to the uncoated diesel engines fueled with JME20. BTE increased by about 7%, and BSFC decreased by 5.3% at full load in the LHR engine run on JME20. HC, CO, and smoke opacity are reduced by about 11.5%, 7.2%, and 4.7%, respectively, at full load for the JME20-fueled LHR engine. Nitric oxide (NO) emission is increased by 11.2% at full load for the LHR diesel engine fueled with JME20. The analysis of the experimental results reveals that the engine performance improves and diminishes engine emissions such as HC, CO, and smoke in the LHR diesel engine but increases NO emission due to the high cylinder temperature and availability of oxygen in the test fuel (JME20). Therefore, further experiments are carried out on the use of antioxidants to reduce NO emissions from the test engine. Two synthetic antioxidants, namely N-Isopropyl-N'-phenyl-1, 4-phenylenediamine (IPPD) and N, N'-Diphenyl p-phenylenediamine (DPPD), each taken at four concentrations viz., 500 ppm, 1000 ppm, 1500 ppm, and 2000 ppm are doped with JME20. The mixtures obtained with IPPD are designated as JME20A1, JME20A2, JME20A3, and JME20A4, where A1, A2, A3, and A4 indicate 500, 1000, 1500, and 2000 ppm respectively. Similarly, the mixtures obtained from doping DPPD in JME20 are designated as JME20B1, JME20B2, JME20B3, and JME20B4, where B1, B2, B3, and B4 indicate 500, 1000, 1500, and 2000 ppm respectively. Before examining the fuel mixtures test engine, they are characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Energy Dispersive Spectroscopy (EDS) for their oxidant behavior. Further, experiments are conducted in the test LHR engine. Due to the combined effects of micro-explosion and the secondary atomization of IPPD-doped JME20 fuels, HC and CO emissions are reduced by 30.6% and 22.4%, respectively, compared to those of diesel operation at full load. The smoke opacity is reduced by 11.5% at full load condition for JME20 A3 in the LHR engine. NO emission is reduced by 11.7% for JME20A3 at full load condition compared to an uncoated engine. The peak heat release rate (HRR) and the peak cylinder pressure are lesser by about 5.6% and 5.1% for JME20B4 in the coated engine (CE), respectively, at maximum engine load. NO, HC and CO emissions are reduced by 6.5%, 17.4%, and 34.6%, respectively, at full load for the JME20B4 fueled in the LHR diesel engine. The next set of experimental studies used two leaves extracted natural antioxidants doped with JME20 to reduce the NO emission and analyze the engine performance also. Natural antioxidants are available in various biomass substances, which can be used for improving human health and fuel oxidation stability. Therefore, the next two sets of experiments are carried out using antioxidants derived from two potentially available biomass substances (i) Albizia lebbeck, and (ii) Pongamia pinnata leaves. Albizia lebbeck leaves, and Pongamia pinnata leaves are characterized by XRD, SEM, FTIR, and EDS for their oxidant behavior. Antioxidant obtained from Albizia lebbeck at various concentrations viz., 500, 1000, 1500, and 2000 ppm is doped in JME20, and the blends are designated as AL1, AL2, AL3, and AL4, respectively. Antioxidant from Pongamia pinnata leaves at 500, 1000, 1500, and 2000 ppm is doped in JME20, and the fuel mixtures are designated as PLA1, PLA2, PLA3, and PLA4, respectively. The combustion, performance, and emissions of the test engine run on antioxidant-doped JME20 fuels in the conventional engine operation and LHR mode are evaluated. Results indicate that among the four antioxidants doped-JME20 fuels, JME20AL4 gives better performance and lower exhaust emissions. The cylinder pressure and heat release rate are lesser by about 4.7% and 6.4%, respectively, at full load, for JME20 AL4. The fuel's delay period and combustion duration are improved by about 26.8% and 10.8%, respectively, at maximum load. NO, HC and CO emissions are reduced by about 17.3%, 19.3%, and 44.2%, respectively, for JME20 AL4, at maximum load. Cylinder pressure is reduced by about 5.9% and the heat release rate by 6.9% for JME20 at a concentration of 2000 ppm in the LHR engine. The engine emissions are reduced by 17.5% and 16.3% for HC and smoke, respectively, at maximum load for JME20 PLA4, in the LHR engine. NO emission is decreased by 16% for JME20 with 2000 ppm (JME20 PLA4) at a higher load in the coated engine