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Impact of dietary modulations on the onset of Type 2 Diabetes in Drosophila melanogaster and its treatment mediated by metallic and polymeric nanoparticles
No full textDiabetes mellitus is one of the most prevalent metabolic disorders of the current century. High calorie diet having high glycemic index (GI) are the major contributors of diabetes. Due to the complex nature of this disease, it is difficult to treat and often leads to huge treatment burden. Numerous studies have tried to understand the detailed mechanism of this disease to design new and effective therapeutic approaches. The application of nanotechnology in the field of diabetes have been proven beneficial. The current study aims to investigate the effect of dietary modulation in the onset of diabetes and established the role of anti-diabetic NPs by using Drosophila melanogaster as a model system. The first objective aims to investigate the effects of dietary advanced glycated end products (AGE). Oral feeding of three types of AGE compounds (i.e. AGE glucose, AGE-fructose and AGE-ribose) was found to alter growth and development of the flies. Beside this, the larva and adults showed persistent hyperglycemic condition, excess fat deposition and micronuclei formation in gut and fat body as well as insulin resistance. The flies also showed increased ROS formation via downregulation of the antioxidant enzyme system. Behavioral defects were also evidenced in the larval and adult locomotion, suggesting neuronal damage. The second objective depicts the role of Strontium ferrite, a metallic nanoparticle as a non-toxic anti-diabetic agent. Files fed with a high fat diet (HFD) were used as a diabetic model. The toxicity profile of the nanoparticles was checked, showing no DNA damage or cytotoxicity. Feeding of the NPs to the diabetic flies demonstrated that, the NPs were able to reduce fly weight, metabolic sugar and triglyceride level, reduce the deposition of fat and also reduce ROS level and behavioral abnormalities. In the third objective, the flies were reared on a high sugar diet (HSD), which tremendously affected their growth and development. Beside this, behavioral alterations was also seen. Hyperglycemia followed by excess fat deposition in the gut, fat body and crop confirmed the diabetic phenotype. A novel polymeric nanoparticle, namely polyvinylpyrollidone-curcumin (PVP-C) was checked for antidiabetic potential. Non-cytotoxic and non-genotoxic potential of the nanoparticles were evidenced from no DNA damage, and absence of trypan blue staining, as well as no phenotypic abnormality. Treatment of PVP-C NPs to the diabetic flies showed reduction of metabolic contents and ROS level. Together the study suggests the role of diet in diabetic onset and importance of nanoparticles having potential to be used alone as an anti-diabetic agent or a combination to deliver therapeutic molecules
Vibration and Buckling of Cracked Laminated Composite Beams with Crack Detection Using Fuzzy Logic
No full textThe laminated composite beams (LCB) witnessed a significant extent of progress in applied engineering applications due to good stiffness to weight, lightweight character and good tailoring ability. However, affected by various static and progressive dynamic loading, crack or crack-like structural defects are inevitable in LCBs. Affected by such load variations, cracks are extremely complex in nature, which raises difficulty for identification and diagnosis of crack-like defects. In this context, the LCBs present a significant and practical research scope under the domain of dynamic and static stability. Apart from the analysis, the identification of damages or structural discontinuities possess a significant research importance to assess the health and functionality of LCBs on a regular basis. Mounting on these significant and potential research aspects, the present investigation is devoted to the structural analysis of LCBs in intact and cracked state by frequency monitoring under free vibration and buckling load variations. Besides, a novel crack detection technique is presented using free vibration and buckling data with Fuzzy Logic Soft Computing tool. The present thesis offers a detailed free vibration and buckling analysis of industry-driven bi-directional woven glass/epoxy and carbon/epoxy LCBs with and without open transverse cracks through experimental and numerical approaches. To this end, a numerical computation for natural frequencies and critical buckling loads is performed on ABAQUS finite element simulation software. A linear beam finite element model is developed on ABAQUS platform and simulated for free vibration and buckling results for non-cracked and cracked LCB. A vibration FFT analyzer is employed for experimental modal analysis and INSTRON 8862 Universal Testing Machine is employed for buckling experiments. It is observed that the numerically simulated results are arrived in line with the experimental outcomes. Based on the developed crack model, the parametric variations are investigated for different parameters. In the present thesis, the free vibration and buckling responses are quantified for various laminated configurations, boundary conditions at supports, span-to-depth ratios and crack signatures. It is shown from the result analysis that the vibration and buckling properties are sensitive to the above-mentioned parameters. Furthermore, significant variations are observed for natural frequencies and buckling loads concerning the crack location and size. In the thesis, the experimental and numerical results concerning each parameter are discussed in detail and conclusions are drawn. During the operational life, the initiation of crack and its existence possesses critical threat to the structural functionality of laminated composites. In this context, the identification of crack location and size is significantly important as it provides a comprehensive knowledge regarding structural state and functionality in advance to avoid such critical threats. To this end, the present research work attempts for crack detection in LCBs using free vibration and buckling responses. Fuzzy Logic tool is employed to train the vibration and buckling data in order to scale the crack location and size. The crack detection using buckling data with Fuzzy Logic has never been attempted before and thus, the present research work is established as a debut attempt. The Fuzzy Logic analysis is performed on MATLAB platform using a Hybrid Mamdani FIS. The simulated vibration and buckling responses for first four modes are fed as input parameters in the developed FIS and the trained data scale the crack signatures as output values. The research attempt for crack detection using vibration and buckling data delivered encouraging results as it expresses similitude with the experimental results
Preparation and Characterization of Freeze-Dried and Electrospun Scaffolds from Chitosan, Gelatin, and Monetite Nanoparticles for Bone Tissue Engineering
No full textChitosan, gelatin, and monetite nanoparticles-based composite scaffolds with tailored structures and properties have great potential for bone regeneration. Herein, we aimed to improve the physicochemical, osteogenic, and mechanical properties of the 3D composites scaffold by the addition of dihydrogen calcium phosphate anhydrous (DCPA, monetite) nanoparticles into the polymer matrix with variation in composition in the developed scaffolds. Scaffolds were fabricated from the viscous slurry containing chitosan, gelatin, and synthesized nano DCPA particles using the freeze-drying and electrospinning method. DCPA nano-sized particles were synthesized using calcium carbonate and phosphoric acid in a water-ethanol medium. The novelty in this thesis lies in the fact that nano dicalcium phosphate anhydrous can enhance the bone regeneration potential of chitosan/gelatin-based freeze-dried and electrospun scaffolds through its chemical and structural modification in vitro to ideally mimic bone apatite. In this case, monetite was used as a bioactive ceramic phase to explore its efficacy in exhibiting both osteoconductive and osteoinductive effects in vitro as well. Moreover, monetite possesses higher solubility than tri-calcium phosphate, octacalcium phosphate, and calcium hydroxyapatite in aqueous solutions at physiological pH and is considered to exhibit a high in vivo resorbability in comparison to other phosphate ceramics. No comparative study has yet been carried out to investigate the mechanical and biological performance of chitosan/gelatin electrospun and freeze-dried scaffold containing monetite as reinforced nano particulate in the microporous/macroporous structure of scaffolds. XRD pattern revealed phase pure DCPA in synthesized nanopowder. Macroporous scaffolds were fabricated by the addition of nano-sized DCPA particles to the extent of 10-20 wt% of total polymer concentration into pure chitosan, pure gelatin, and chitosan-gelatin solution with solid loading varying between 2 to 2.5 wt.%. The prepared scaffold showed significantly high interconnected porosity with pore size varying between 90-390 micrometers. With the addition of DCPA nanoparticles, the average pore size, porosity, swelling, and rate of biodegradation of the prepared scaffolds decreased. With an increase in nano ceramic phase content from 10 wt.% to 20 wt.% of total polymer concentration, the compressive strength of the scaffold increased. Scaffold containing 20 wt.% DCPA revealed the highest average compressive strength of 1.93 MPa for CS-M20, 2.43 MPa for GM20, and 2.15 MPa for CGD20. Higher cellular activities were observed in DCPA-containing scaffold as compared to pure gelatin, pure chitosan and chitosan-gelatin (CG) scaffold suggesting the fact that nano DCPA incorporation into the scaffold stimulated superior osteoblast attachment and proliferation as evident from MTT assay and scanning electron microscopic (SEM) investigation of pre-osteoblast cultured scaffolds. A higher degree of lamellipodia and pseudopodia extensions and superior spreading behavior of osteoblasts were observed in FESEM images of MG-63 cultured DCPA-containing scaffolds. The results demonstrated that both mechanical strength and osteogenic properties of gelatin-chitosan scaffold could be improved by the addition of monetite nanoparticles into it. Separately, fibrous scaffolds were prepared from a combination of pristine chitosan, pristine gelatin, and chitosan-gelatin solution in TFA/DCM and an aqueous suspension of DCPA nanoparticles up to 7 wt% of total polymer concentration using electrospinning technique. The electrospun scaffold with an average fiber diameter varying between 70 to 380 nm was successfully prepared at 20 kV, 15 cm of distance between collector and needle tip from a suspension containing up to 7 wt% of DCPA in total polymer concentration. With the incorporation of monetite nanoparticles, the average fiber diameter, porosity, swelling, and rate of biodegradation of the nanofibrous scaffolds decreased. The results demonstrated that both physiochemical properties and mechanical strength of pure gelatin, pure chitosan, and chitosan-gelatin scaffold could be improved by the addition of monetite nanoparticles into it. Electrospun nanofibers containing 7 wt% monetite exhibited the highest average tensile strength of 12.2 MPa for CH-DCPA7, 18.8 MPa for GD7, and 14.34 MPa for CGM7. Higher cellular activities were observed in monetite-containing nanofibers as compared to pure gelatin, pure chitosan and chitosan-gelatin (CG) nanofibers suggesting the fact that nano monetite addition into the scaffold stimulated superior osteoblast attachment and proliferation as evident from MTT assay and scanning electron microscopic (SEM) investigation of pre-osteoblast cultured scaffolds. A higher degree of lamellipodia and pseudopodia extensions and superior spreading behavior of osteoblasts were observed in SEM images of MG-63 cultured monetite containing scaffolds. The results demonstrated that both mechanical strength and osteogenic properties of pristine chitosan, pristine gelatin, and chitosan-gelatin matrix could be improved by the addition of monetite nanoparticles into it
Studies on the Crystal Structure, Electrical Conductivity and Oxygen Transport Parameter of A0.5Sr0.5Co0.2-xBxFe0.8O3- [A = La, Ba; B = Zn, Al; x = 0 – 0.2] Perovskite Oxides
No full textLa0.5Sr0.5Co0.2Fe0.8O3-δ (LSCF) and Ba0.5Sr0.5Co0.2Fe0.8O3-δ (BSCF) powders were prepared by combined EDTA-citrate combustion route, and both the powders showed a single perovskite phase. The LSCF oxides exhibited rhombohedral crystal structure, while BSCF oxides showed cubic structure. The thermogravimetric study indicated that the mass loss behavior is dominated by the thermal reductions and the oxygen non-stoichiometry in the samples. The room temperature and the high-temperature oxygen non-stoichiometry study revealed that the BSCF oxides contain higher oxygen non-stoichiometry than LSCF. The thermal expansion coefficient (TEC) of LSCF and BSCF samples measured from RT – 800 oC were found to be 17.58 and 17.32×10-6 K-1, respectively. Microstructure and electrical properties were significantly affected by the variation in the sintering condition (temperature and time). The grain size (d50) of the LSCF and BSCF samples was 0.75 μm and 19.5 μm, respectively, when sintered at a temperature of 1150 oC for 4 h. Temperature-dependent conductivity of the samples showed metallic conductivity in the high-temperature region and exhibited conductivity hysteresis while measured on heating and cooling. The conductivity of BSCF samples is lower than that of LSCF samples when sintered under identical conditions. The observed difference is comprehended from the combined effect of the sintered sample's defect chemistry change and grain size. The faster electrical conductivity relaxation kinetics noticed in BSCF oxides compared to LSCF oxides is correlated to the combined contribution of higher oxygen vacancy concentration and mobility of oxygen vacancies. The values of surface exchange kinetics (Kchem) measured at 850 oC was found to be 2.86×10-4 cm s-1 and 7.54×10-2 cm s-1 while the values of chemical bulk diffusion coefficient (Dchem) were 1.6×10-6 cm2 s-1 and 8.62×10-3 cm2 s-1 for LSCF and BSCF oxides respectively. Grain size effect on oxygen exchange kinetics of LSCF and BSCF oxides revealed that both Dchem and Kchem increase with the grain size increase.
A thorough study on zinc substituted A0.5Sr0.5Co0.2-xZnxFe0.8O3-δ (A = La and Ba; x = 0 – 0.2) perovskite oxides has been carried out. All the prepared La-containing powders exhibited the distorted rhombohedral crystal structure, while the Ba-based powders showed cubic symmetry. The lattice volume, oxygen non-stoichiometry, electrical conductivity, and oxygen transport parameters varied drastically with the substitution of zinc in place of cobalt in the system. The microstructural study revealed the grain size enhancement with the increase in the zinc content in La-based samples when identical sintering conditions were maintained. A typical nature showing an increase in the grain size of 11.2 – 14.3 μm from 0.0 – 0.10 zinc content and then decrease is noticed in Ba0.5Sr0.5Co0.2-xZnxFe0.8O3-δ (x = 0 – 0.2) system. The La0.5Sr0.5Co0.1Zn0.1Fe0.8O3-δ (LSCZF10) sample showed the highest electrical conductivity while the minimum for the La0.5Sr0.5Zn0.2Fe0.8O3-δ (LSZF) sample. In Ba-containing zinc substituted oxides, a linear decrease in the electrical conductivity is observed. The conductivity deviation observed with substitution level is a combined effect of the difference in concentration of charge carriers, the oxygen vacancies, the average B-site ionic radius, and the grain size of the samples. Oxides prepared with x = 0.10 (LSCZF10) exhibited the highest Kchem (1.11×10-3 cm s-1), and Dchem (1.19×10-5 cm2
s-1) values measured at 850 oC, compared to others. In the Ba0.5Sr0.5Co0.2-xZnxFe0.8O3-δ (BSCZF) system, the calculated Dchem values were found to vary between 3.9×10-4 to 4.5×10-3 cm2 s-1 while the Kchem values varied between 5.4×10-3 to 9.8×10-3 cm s-1 with increasing substitution level (x) in the range 0 – 0.2.
The electrical transport properties, namely electrical conductivity, chemical bulk diffusion coefficient (Dchem), and surface exchange coefficient (Kchem) of A0.5Sr0.5Co0.2-xAlxFe0.8O3-δ (A = La and Ba; x = 0 – 0.2) perovskite oxides were studied systematically. All the studied compositions exhibited a distorted rhombohedral and cubic crystal structure for lanthanum and barium-based oxides, respectively, not prejudiced by the aluminum substitution level in the system. X-ray photoelectron spectroscopic (XPS) study confirms the variation in the average oxidation state B-site cations and active oxygen vacancy concentration in the samples as a function of aluminum substitution. The lattice volume in La0.5Sr0.5Co0.2-xAlxFe0.8O3-δ (x = 0 – 0.2) (LSCAF) series found to be least (347.0761 Å3), while the oxygen non-stoichiometry () found to be highest (0.12) in the sample prepared with x = 0.1 as compared to other studied ones. The lattice parameters of the Ba0.5Sr0.5Co0.2-xAlxFe0.8O3-δ (BACAF) powders synthesized in the present work were in the range of 3.9557 – 3.9564 Å. The microstructural study revealed grain size refinement with increasing aluminum content in the sample when sintered under identical conditions, irrespective of the change in A-site cation substituent. In the Ba0.5Sr0.5Co0.2-xAlxFe0.8O3-δ (BSCAF) system, with increasing substitution level in the range 0 – 0.2, the Kchem and Dchem values ranged from 5.6×10-3 to 9.4×10-3 cm s-1 and 2.6×10-4 to 1.3×10-3 cm2s-1 respectively. The values of Dchem and Kchem of La0.5Sr0.5Al0.2Fe0.8O3-δ calculated from ECR spectra were found to vary between 2.03×10-5 cm2 s-1 to 1.99×10-6 cm2 s-1 and 1.034×10-3 cm s-1 to 5.26×10-4 cm s-1 respectively, with an increase in the grain size ranging from 0.93 – 5.88 μm
Reading Ascetic Ideals in Indian Nationalist Thought
No full textDuring the freedom struggle movement in India, Mohandas Karamchand Gandhi (1869-1948), Rabindranath Tagore (1861-1941) and Aurobindo Ghose (1872-1950) adopted asceticism as an indigenous epistemology of hardship (nishkama karma) and spiritual power to counter colonial emasculation of Indian men. They revived the image of the karmayogi—the (male) body-at-service—as the anti-colonial subject to deliver defeated men and create an alternative reality dominated by divine oneness. Gandhi’s, Tagore’s and Ghose’s remasculinizing agenda indexed Indian manliness in three different dynamics. Tagore’s anti-colonialism employed an erotic politics dominated by ‘ascetic purity’ of love to recover androgyny as a legitimate cultural construct for Indian men. Ghose’s idea of anti-colonial man, in his post-political years, shifted from being a warrior ascetic to an androgynous yogi. Gandhi’s concept of ‘exemplary’ manliness was mapped onto the body of ‘God’s eunuch’. Drawing on lives and works (political and textual) of Tagore, Ghose and Gandhi, this thesis explores these thinkers’ modes of ‘oppositional’ masculinity. Positioning Tagore’s erotic politics along with Ghose’s and Gandhi’s celibate theorizations of a new India, the thesis traces their individual gender politics that was generated through the links they made between the body and the nation. While Ghose and Gandhi perceived celibacy as a means of Indian (male) superiority within the socio-cultural sphere, Tagore took it to be a tool of ‘masculine’ hegemony and of institutional violence. Locating these thinkers’ gendered decolonization in dialectic relationships, the thesis outlines their personal responses to moral tensions which Indian intelligentsia experienced between sexuality and its renunciation, and between love for the beloved and love for the motherland in their national self-fashioning
Exploring Deep Learning Techniques for Data-driven Air Quality Modeling and Forecasting
No full textAir pollution has become a significant issue, especially in high-density urban areas. Since the first industrial revolution in the 19th century, human activities have badly affected the earth and the environment. The world has become inhabitable day by day due to inappropriate human activities, construction patterns, and unsustainable cities development. Moreover, due to these activities, environmental air quality has become worst day by day. World Health Organization (WHO) provided evidence that urban air pollution is becoming the main threat to human health, especially in high-density countries like China and India. Changes in air pollution are basically affected by low-frequency and high-frequency pollution in other places and their weather conditions. In that situation, changes in meteorological parameters and spatial attributes should be considered and identify the correlation between them. People are paying more attention to changes in air quality and its control. Air pollution forecasting is one of the essential preventive steps to control air pollution. Based on the pollutant forecasting results, the relevant department and policymakers get the early information on pollutant concentration in a particular location. This information can help them adjust some critical measures according to pollutant emission sources to control pollutant emissions and their adverse impact on public health. However, pollution forecasting has become challenging due to its complexities with time-space nonlinearities, weather conditions, and spatial-temporal impact of nearby locations. In order to address these issues, this research work proposes various approaches, which are summarized as follows. In the first contribution, this research work presents a neural network based Convolutional Long Short term Memory-Sparse Denoising Autoencoder (CLS) model to forecast the PM2.5 level under meteorological conditions. The CLS model identifies the vast dataset’s hidden features, performs pollutants’ temporal modeling, and reconstructs the predicted output in the dynamic fine-tuning layer to get robust prediction results in a real time environment. The proposed model has experimented with different datasets, and its results show the model’s efficiency in air quality modeling. In the second contribution, this research work developed Temporal Convolutional Denoising Autoencoder (TCDA) network, a hybrid PM2.5 prediction framework that can perform rapid extraction of complex dataset’s features, handle missing values and improve PM2.5 prediction results. The model can reconstruct the corrupted, missing values and handle the different patterns of missing values to enhance the short-term PM2.5 forecasting results. In the third contribution, this research developed a Multi-Directional Temporal Convolutional Artificial Neural Network (MTCAN) model to impute and forecast PM2.5 pollutant concentration in a single training process. The main idea of the multi-directional properties of MTCAN is to maintain the temporal correlation within the features’ measurement and meteorological and pollutant variables to impute PM2.5 missing values. The MTCAN model performs feature learning and sequential modeling simultaneously with a wide range of past observations for long-term forecasting, minimizing memory size requirement and training cost. In the fourth contribution, this research work presents a newly developed multi-step ahead pollution forecasting model with a multi-input, multi-output learning process. The proposed model can work effectively under meteorological conditions and spatial impact. The proposed model has better long-term forecasting accuracy as compared to the traditional statistical and machine learning models. The proposed Multi-Output Long Short-Term Memory (LSTM) Autoencoder (M-LSTMA) accumulates each step prediction value to perform multi-step ahead forecasting for multiple pollutants in a single training process. The results show the model’s effectiveness, where we need to know the overall air pollution level for a particular area. In the fifth contribution, this research work proposed a novel PM2.5 forecasting model named as Multi-Output Temporal Convolutional Network Autoencoder (MO TCNA), which serves both the PM2.5 and PM10 pollutants forecasting for various locations instead of performing single output and site-specific pollutant forecasting for an overall idea of pollution level for a particular region. The proposed work developed a Recursive-Multi-Input, Multi Output (R-MIMO) strategy to improve multiple pollutant forecasting accuracy for the long-term period for different sites in a region. Experimental results indicate that the proposed models are superior to baseline single-output and multi-output forecasting models, which proves their effectiveness in regional air quality modeling. The efficiency of all the proposed models has experimented with two datasets for evaluation, and the comparative results illustrate the efficiency of all the models for an effective environmental decision support system
Adaptive Control Design for a Three Phase Grid Connected Photovoltaic System with Experimental Analysis
No full textIn view of meeting increasing power demand while minimizing carbon emission, more emphasis is being given to generate the power from renewable energy sources. Due to availability of abundant solar radiation, and low operational cost, the installation of PV based renewable power generation is increasing rapidly as compared to other renewable sources. The PV power generation can be operated either in standalone mode or grid connected mode. The control of grid connected PV power generation is challenging due to intermittent solar irradiance, and nonlinear environment dependent characteristics of PV source. The maximum power of a PV source depends upon the environmental parameters such as ambient temperature and irradiance. A Maximum Power Point Tracking (MPPT) algorithm is employed in PV control system to extract the maximum power from solar PV panels. The MPPT algorithm generates the reference PV voltage for PVVC. For single stage Grid Connected PV System (GCPVS), a PV Voltage Controller (PVVC) is employed to track the reference PV voltage, and simultaneously generates the reference grid current. Further, Grid Current Controller (GCC) tracks that reference grid current by controlling the switching of the inverter. To reduce the PV voltage ripple in single-stage GCPVS, DC-link capacitor is connected at the input of inverter. Also, coupling filters (such as Resistive Inductive (RL) filter) are used at the output of inverter to reduce the switching ripple in inverter output current. The performances of the PVVC and GCC depend upon the parameters of PV module, DC-link capacitor and RL filter. The internal resistance of PV module varies with its operating point resulting uncertainties in PV side. The DC-link capacitor varies due to aging. Coupling filter impedance varies with age, temperature and operating conditions. Further, grid current quality at low irradiance is an integral issue of GCPVS as all the passive components are designed at nominal power rating. To handle parametric uncertainties and intermittency in irradiance, it is necessary to design efficient adaptive controllers for GCPVS. The thesis focusses on design, development, and practical realization of different adaptive control schemes for achieving effective grid integration of single-stage three phase GCPVS. The thesis first develops an aging linked model of PV model by considering aging in PV parameters. Subsequently, a Quadrature Axis Small Signal Model (QASSM) of Grid Connected Inverter (GCI) with DC battery by considering the internal resistances, such as Equivalent Series Resistance (ESR) of DC link capacitor, internal resistance of PV cell, and internal resistance of coupling filter, is developed. This model is used to analyze the eigenvalues of the GCI. Subsequently, a QASSM of GCPVS is developed by considering GCI with PV source. From the eigenvalue analysis of the GCPVS , it is observed that internal resistance of the PV causes instability in GCPVS. Then the performances of GCPVS are evaluated at different aging periods. From this performance analysis, it is observed that PV voltage ripple, MPPT tracking efficiency and THD of grid current are deteriorated with increase in aging of GCPVS. Subsequently, the thesis develops different adaptive control schemes for GCPVS to handle the parametric uncertainties in GCPVS. First, a real-time parameter estimation based adaptive controller scheme, called as Self-tuning Sinusoidal Recursive Controller (STSRC), for GCPVS has been developed to handle the parametric uncertainties. The STSRC scheme employed an Improved Linear Sinusoidal Tracer (ILST) based Recursive Least Square (RLS) estimation called as IRLS. The IRLS estimates the GCPVS parameters effectively under distorted grid voltage profiles, and under low speed sampled data. The STSRC employed for both PVVC and GCCs. Efficacies of the proposed STSRC scheme are compared with Proportional Integral (PI) controller, Integral Sliding Mode Controller (ISMC) and Robust Nonlinear Adaptive Backsteeping Controller (RNBC). The comparison envisages that STSRC provides improved performance of GCPVS in terms of achieving low PV voltage ripple and low grid current THD. Then, a Lyapunov Based adaptive Voltage Controller (LBAC) is developed to control the PV voltage. The Total Harmonics Distortion (THD) of grid current increases at low irradiation. The THD of grid current not only depends upon the GCC but also depends upon the accurate tracking of PV voltage. Oscillation in PV voltage causes the distortion in grid current. This further degrades the grid power quality. Thus, tracking performance of PVVC plays an important role in better power extraction and in overall grid power quality. The LBAC is designed to provides critically damped PV voltage tracking with desired settling time despite the different disturbances in GCPVS. Efficacies of the proposed LBAC are compared with PI controller and RNBC. The comparison envisages that LBAC provides smooth critically damped PV voltage tracking with low voltage ripple as compared to PI controller and RNBC. The improved PV voltage tracking, yielded by LBAC, improves the THD of grid current in both high and low irradiance as compared to PI controller and RNBC. Finally, a cascaded Model Reference Adaptive Controller (MRAC) scheme is developed for GCPVS to handle the parametric uncertainties and disturbances. Apart from uncertainties, measurement noise affects the performances of the controller in GCPVS. However, use of additional filtering of feedback signals reduces the stability margins of controller. A cascaded MRACs are designed for both PVVC and GCC to achieve improved performances even under measurement noise. The proposed control scheme comprises of a reference model, and a Lyapunov based parameter adaptation scheme which provides the nominal tracking performance despite uncertainties in the GCPVS dynamics. Two separate reference models are chosen respectively for PVVC and GCC to define the critically damped desired tracking characteristics. The efficacies of the designed MRAC scheme are compared with PI controller, RNBC, LBAC and ISMC. Due to cascaded MRAC, the designed MRAC scheme is more noise resistant as compared to other controllers. Further, the MRAC scheme provides critically damped PV voltage response with reduced PV voltage ripple, and low grid current THD as compared to PI controller, ISMC, RNBC and LBAC. All the adaptive control schemes are first verified through simulation studies in MATLAB/SIMULINK environment. Then, efficacies of the different proposed adaptive control schemes are verified through real-time implementation using the 2.25 kW GCPVS prototype, developed in our laboratory. From the comparative analysis, it is observed that both LBAC and MRAC schemes exhibit critically damped PV voltage response with less ripple, and less grid current THD. However, MRAC scheme provides improved performance in robust PV voltage tracking with reduced grid current THD under the measurement noise as compared to PI controller, ISMC, RNBC and LBAC
Diversity Of Biofilm-Forming Filamentous Fungi From Sundarban Mangrove Ecosystem and Sequestration Of Chromium By Fungal Biofilm and Biosynthesized Iron Oxide Nanoparticles
No full textThis thesis illustrates the potential of biofilm-forming manglicolous filamentous fungi in hexavalent chromium [Cr(VI)] sequestration and green synthesis of iron oxide nanoparticles. In this study, sediment and water samples were collected from three sites of Indian Sundarban mangrove ecosystem, i.e., Jharkhali, Bali, and Canning. A total of sixty three fungal isolates were obtained from both sediment (fifty isolates) and water samples (thirteen isolates) of these three sites, out of which Bali island possessed the highest fungal population, i.e., 1.5×105 CFU/g in sediment and 3.2×104 CFU/ml in the water sample. Among sixty three isolates, twelve isolates exhibited strong adherence to the glass surface, indicating potential biofilm-forming ability. Colony morphology and microscopic analysis of fungal isolates revealed that fungal isolates belonged to genus Aspergillus, Penicillium, Fusarium, and Trichoderma. Out of twelve fungal isolates, Aspergillus niger BSC-1 showed the highest biofilm-forming ability and Cr tolerance capacity. Further, the present work probes various stages of biofilm formation by Aspergillus niger BSC-1. Scanning electron micrograph and confocal micrograph depicted the development of fungal biofilm comprised of six stages, i.e., (i) adsorption, (ii) active attachment, (iii) germling and monolayer formation, (iv) hyphal development and formation of ECM, (v) maturation of ECM, and (vi) dispersal of spores. At the maturation stage (36 h), the thickness of biofilm was observed up to ~15 μm. Further, ATR-FTIR spectroscopic analysis exhibited peaks at 3398 cm-1, 2930 cm-1, 1571 cm-1, 1391 cm-1, 1092 cm-1, and 977 cm-1, which confirmed the presence of protein, carbohydrate, and lipid in the biofilm-associated matrix. To determine the efficacy of filamentous fungal biofilm in heavy metal detoxification, two morphologically diverse biosorbents, such as fungal pellet, i.e., planktonic phase and fungal biofilm were prepared. The removal of Cr(VI) using both the biosorbents revealed that fungal biofilm demonstrated significantly (P<0.05) higher Cr(VI) removal efficiency, i.e., 97.81±2.5% than the fungal pellet. The batch adsorption study showed that the highest Cr(VI) removal was attained at 40°C and pH 3 with 3 g/L of fungal biofilm. The adsorption isotherms, kinetic model, and thermodynamic analysis suggested endothermic and monolayer chemisorption of Cr(VI) onto the surface of the fungal biofilm. The biosorption process was optimized using response surface methodology (RSM) having Central Composite Design (CCD) interface, which suggested the quadratic model as the most suitable model for viii Cr adsorption having high significance (P<0.0001). The 3D surface plots among three key variables, i.e., pH, temperature, and Cr concentration, revealed that maximum sequestration, i.e., 92.39 %, was achieved at 40°C, pH 3, and 30 mg/L metal concentration using fungal biofilm. Regeneration study demonstrated that fungal biofilm retained 87.19±3.23 % of Cr(VI) removal efficiency with no significant loss after five successive adsorption/desorption cycles. Additionally, twelve fungal isolates were utilized for extracellular synthesis of iron oxide nanoparticles (IONPs) which were characterized using by UV-Vis spectroscopy, ATR-FTIR spectroscopy, Raman spectroscopy, XRD, electron microscopy (TEM and FESEM), zeta sizer and VSM. It was found that only A. niger BSC-1 was able to synthesize crystalline superparamagnetic IONPs (Fe3O4) of 20-40 nm size, which was utilized for the removal of Cr(VI) from aqueous solution. The batch experiment revealed that significantly (P<0.05) high Cr(VI) removal was at 40°C and pH 3 with 2.5 g/L of IONPs dose. Similar to biosorption, the adsorption isotherm and kinetic model suggested monolayer adsorption of Cr onto the IONPs surface. The presence of coexisting cations and anions did not exhibit any competitive effect on Cr(VI) removal revealing the selectivity of mycosynthesized IONPs towards Cr(VI). Regeneration study confirmed that IONPs conserved their Cr(VI) removal efficiency with minimal loss (19.3%) after five adsorption/desorption cycles. Further, X-ray photoelectron spectroscopy (XPS) indicated that both adsorption and redox reactions were involved in Cr(VI) detoxification. To understand the genetic features of biofilm formation and metal fungi interaction, whole genome sequencing of A. niger BSC-1 was performed, which revealed the presence of rodA, exgA, and Ags genes which are involved in initial adhesion to surface and matrix formation, respectively, during biofilm growth. Semi-quantitative qRT-PCR analysis confirmed the role of Ags1 and P-type ATPase in biofilm formation and Cr resistance, respectively. Several other genes encoding metalloprotease, copper and zinc binding proteins, and NADH-dependent oxidoreductase were also found in the genome of A. niger BSC-1. These proteins are also involved in heavy metal tolerance and nanofabricatio
Managing Customer Relationship Quality in Wellness Hotels and Resorts in India: A Netnography Approach
No full textThere is no time for relaxing in today’s fast-paced and stressful environment. Then there’s wellness tourism to save the day. People are opting for wellness therapies that may revitalise and detoxicate the body, making it feel youthful and healthy as awareness of a healthy lifestyle grows. India can distinguish itself by delivering indigenous medical therapies through the AYUSH healthcare system, including Ayurveda, Yoga and Naturopathy, Unani, Siddha, and Homoeopathy. Recently, the Indian Ministry of Tourism expressed concern over the quality of services in organised and unorganised wellness care hotels and spas. The study is driven by a desire to solve the underlying issue and comprehend the critical factors influencing service quality in the wellness tourist business. The research examines how these wellness hotels and resorts have undertaken strategies to improve service quality management. This study is inspired by research on consumer sociability, service provider expertise, organisational service quality characteristics, and their significance in building customer relationship quality based on trust, commitment, and satisfaction. The current study fills gaps in the literature by studying firm-level service dimensions and personnel-level attributes and their direct influence on driving customer relationship quality. The Indian wellness hotels and resorts served as the research backdrop to achieve the research aims. The information was gathered as unstructured data from TripAdvisor user reviews. The respondent sample was drawn through convenience and purposive sampling. The collected reviews were subjected to preliminary evaluations to filter and refine the data for subsequent research. Following these assessments, sentiment analysis was used to understand customer sentiment toward the services provided at the selected resorts, both at the firm and therapist levels, using supervised, unsupervised machine learning and LEXICON approaches. The proposed model was then evaluated and validated using multiple linear regression. RIDIT and GRA precedence analysis were used to prioritise the service quality dimensions. vii The findings show that therapist characteristics are essential when a customer’s primary goal is to engage in wellness treatment. Furthermore, firm-level factors are vital in driving customer connections. The most influential dimensions that drive consumer trust, satisfaction, and commitment are tangibility, responsiveness, expertise, mindset-similarity, and sociability. Customer orientation was discovered to be minimal in improving customer relationship quality. These findings add to the knowledge on service quality and relationship quality by empirically explaining their determinants and outcomes. The study also demonstrates how social media and data analytics may acquire customer insights. The findings provide fresh insights for designing focused engagement and relationship-building strategies for wellness hotels and resorts from a managerial standpoint. Furthermore, the study envisions the future development and application of data analytics, machine learning, and artificial intelligence in management and social science
Hydroxyapatite/Lead-free Ferroelectric Composites Synthesized by Mechanochemically Assisted Solid State Reaction Route for Orthopaedic Applications
No full textWith the ageing population and rise of accidents and several bone-related diseases, human beings require a substitute material to act as an artificial bone. Recent trends in the healthcare industry over worldwide suggest that joint replacement surgery is likely to gain much attention. From the application point of view, biomaterials have been used to replace many body parts like hip, knee, teeth, ankle, elbow and other joint damages. Hydroxyapatite (HAp) is a bioactive and biocompatible material having a crystal structure similar to that of bone minerals. Due to having poor electrical and mechanical properties of HAp, its use is limited for non-load-bearing applications. But, several studies show that for load-bearing applications, a dense form of HAp can exhibit appropriate mechanical properties. Well-defined particle morphology of HAp powder makes it quite effective in biomedical applications. It has been reported that composites of HAp with suitable leadfree piezoelectric materials can enhance mechanical, electrical, and biological properties. Synthesis of HAp/lead-free piezoelectric nano-composites is highly promising since it can enhance mechanical, electrical properties and can also promote cell attachment. Bone tissue has a very low piezoelectric co-efficient of 0.7pC/N, and it responds to mechanical stress like different movements of the body, resulting in the formation of electrical dipoles. These properties lead to the development of a new field of bone remodeling research. In this work, potential lead-free piezoelectrics are selected to make composites with HAp for better cell-material interactions for orthopaedic applications. From the available literatures, Ca10(PO4)6(OH)2, BaTiO3, 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3, and 85.4(Bi0.5Na0.5)TiO3-2.6(BaTiO3)-12(Bi0.5K0.5)TiO3 are taken as parent materials for composite formation. Following is the list of materials selected for the present study. (a) Ca10(PO4)6(OH)2/(HAp) (b) BaTiO3(BT),0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3(BZT-BCT), 85.4(Bi0.5Na0.5)TiO3-2.6(BaTiO3)-12(Bi0.5K0.5)TiO3 (BNT-BT-BKT) (c) xHAp/(1-x) BT (x = 5, 10, 15, 20 wt.%) (d) xHAp/(1-x) BZT-BCT (x = 5, 10, 15, 20 wt.%) (e) xHAp/(1-x) BNT-BT-BKT (x = 5, 10, 15, 20 wt.%) Effect of sintering temperature on densification and resultant mechanical, electrical, and biological properties of mechanochemically processed HAp samples was investigated. HAp samples were sintered at 1200, 1250, and 1300 oC for 4 h. Hap samples sintered at 1250 oC showed better mechanical properties, which was attributed to their having smaller grain size compared to HAp samples sintered at higher temperatures. Nearly same value of dielectric constant (εr) and better cell proliferation were exhibited by HAp samples sintered at 1250 oC and 1300 oC, respectively. At ~210 oC, in all the samples sintered at different temperatures, a dielectric anomaly was obtained, which was attributed to the phase transition temperature of the HAp system. Dielectric properties near phase transition temperature showed a dielectric relaxation type of behaviour attributed to the reorientational motion of OH- ions in the HAp system. Higher cell proliferation and viability were exhibited in HAp1300 samples, whereas comparatively equivalent cell growth and higher mechanical strength were observed in HAp1250 samples. BaTiO3 (BT), 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT), 85.4(Bi0.5Na0.5)TiO3-2.6(BaTiO3)-12(Bi0.5K0.5)TiO3 (BNT-BT-BKT) lead free ferroelectric ceramics were synthesized by high energy ball milling (HEBM) assisted solid-state reaction route. Crystallite size of the HEBM powders was found to be in the nano-range. XRD, SEM, dielectric, polarization vs electric field (P~E) loop and mechanical characterizations and analysis of these sintered ceramics were carried out. Lower calcination and sintering temperatures, along with better densification and having smaller average grain size compared to the same systems synthesized by the solid-state reaction route, were optimised. Enhanced RT values of εr~2875, 5133, and 1701 and lower values of tanδ~0.013, 0.015, and 0.058 were obtained in BT, BZT-BCT, and BNTBT- BKT sintered ceramics, respectively. Well saturated P~E hysteresis loops were obtained for all the ceramics, which confirmed their ferroelectric behaviour. Hardness value ~7.23GPa, 5.53 GPa, and 5.16 GPa was obtained for BT, BZT-BCT, and BNT-BTBKT sintered ceramics, respectively. As bone is a piezoelectric material; therefore, fabricating a composite of HAp with lead-free piezoelectric can lead to the development of a new field in bone remodeling process. From literature survey, BT, BZT-BCT, and BNT-BT-BKT ferroelectrics were selected to synthesize composites with HAp to further increase its mechanical, electrical and biocompatibility properties. All three composite systems showed the formation of intermediate phases during sintering. Inhibition of grain growth in the sintered body of the composites can be attributed to the formation of secondary phases, which provide more surface area to volume ratio with some small pores and favour cell-material interaction. Reduced value of εr of the composite system was related to the isolation of ferroelectric particles by Hap particles, which was supported by different theoretical models. Improved mechanical properties of composite systems were well correlated with the microstructures. Nano sized grains were retained in the microstructure, which is due to the processing of starting powders with HEBM method. Among all of the composites, HAp/BT and HAp/BZT-BCT showed better mechanical properties compared to HAp/BNT-BT-BKT composites. For load-bearing applications, implants with enhanced mechanical properties are required. Whereas biological properties were studied for better cell growth and healthy implantation ascertainment. Therefore, biological properties such as cell proliferation, cell attachment, cytotoxicity, live/dead assay, and hemocompatibility of HAp/BT and HAp/BZT-BCT composite samples were carried out. Among different composite compositions, better mechanical, electrical, and cell culture properties were obtained in 10HAp/90BT and 10HAp/90BZT-BCT composite samples. Hardness of value ~4.61 GPa and ~4.12 GPa, fracture toughness of value ~3.64 MPa.m1/2 and ~3 MPa.m1/2 were obtained in 10HAp/90BT and 10HAp/90BZT-BCT composite samples, respectively. Effect of poling on ALP activity was carried out on poled HAp/BT and HAp/BZT-BCT composite samples