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Numerical and Semi Analytical Solutions of Applied Fractional Differential Equations
No full textReal-world phenomena are typically modeled by various differential equations with integer orders, and differential equations frequently explain their behavior. It might sometimes be valuable to use non-integer order derivatives to understand the behavior of the physical problems. In this context, fractional calculus (FC) has provided a unique opportunity to serve the cause. Fractional-order models are more realistic and adapted to real situations than integer-order models because of their hereditary nature and ability to describe memory specifications. Fractional calculus has grown significantly in prominence and popularity over the last three decades, primarily due to its recognized applicability in various disciplines including science and engineering. The unique non-local characteristics of fractional derivatives are among their most remarkable aspects. This non-local feature offers a potent tool for simulating complex systems with long-range interactions, anomalous behavior, and memory effects. As such, some standard fractional operators have been defined to handle the fractional differential equation viz. Grünwald–Letnikov, Riemann-Liouville and Caputo fractional operators. This dissertation addresses solving and analyzing different types of physical and real world problems in particular, wave equations, heat equations, telegraph equations, financial models, and biological models. These problems are usually governed by fractional order ordinary and partial differential. It may not always be possible to get analytical solutions to these fractional differential equations.Accordingly, various semi-analytical and numerical methods, including the modified extended tanh method, homotopy perturbation method, Taylor series expansion method, block pulse function method, and triangular basis function method, are applied here to handle governing fractional differential equations corresponding to the problems undertaken. Some hybrid methods such as Elzaki-homotopy perturbation method, Sumudu-homotopy perturbation method, and Aboodh-homotopy perturbation method have been applied where Elzaki, Sumudu and Aboodh transforms helps in dealing with non linearity in the fractional differential equations. The convergence of each method is discussed numerically, and validation of the findings has been shown. The effect of the involved parameters has been illustrated graphically for all considered models. Generally, the physical parameters used in different physical problems and dynamical models are assigned crisp values. But in practical scenarios, these parameters may be uncertain in nature due to errors in the measurements, observations, or experiments. The involvement of uncertain parameters mimics the actual practical problems and leads to uncertain differential equations. The uncertain parameter(s) may be considered in terms of interval or fuzzy number. Further, Homotopy perturbation method has been extended with the aid of the double parametric concept of fuzzy numbers to handle uncertain differential equations. Considering those above, the purpose of the thesis has been to examine several fractional order models that occur in the (i) wave equations, (ii) heat equations, (iii) telegraph equations, (iv) economical, and (v) biological models. In the one of the above mentioned problems, initial conditions and involved parameters are also considered as uncertain. The models are further investigated using a variety of computationally effective analytical or numerical approaches (where appropriate)
Efficient Security Enhancement Techniques for Ultra-reliable Low Latency Communication in 5G and 6G Wireless Networks
No full textThe fifth generation (5G) wireless networks have revolutionized the current communication landscape by enabling many futuristic and smart applications. This brings 5G to introduce an innovative service like Ultra-reliable Low Latency communication (URLLC) to facilitate mission-critical 5G applications such as industrial automation, autonomous driving, smart healthcare, and smart grid operations. Most importantly, URLLC enables ultra-high reliability (i.e., up to 99.999%) and low latency (i.e., < 1ms) data transmission to achieve the desired Quality-of-Service (QoS) of these mission-critical applications. To ensure the stringent QoS requirement, URLLC uses short packet finite block length signals. However, the exponential rise in wireless data traffic generated from billions of smart Internet-of-Things (IoT) devices utilizing URLLC service is highly vulnerable to external eavesdropping and security threats. Moreover, the finite block length constraint and low latency criteria eliminate the possibility of utilizing complex cryptography-based security techniques for URLLC. In this regard, Physica layer security (PLS) has emerged as a potential technique for providing lightweight security enhancement for URLLC by exploiting the randomness of wireless channel characteristics. Therefore, this dissertation proposes the development of efficient security enhancement techniques utilizing PLS for URLLC mission-critical 5G applications. The first contribution of this dissertation is to ensure the security of URLLC signal transmission to the cell edge users in an IoT network. In this regard, the cooperative non-orthogonal multiple access (CNOMA) has emerged as a promising 5G technology that ensures the reliability of signal transmission by cooperatively transmitting the information of cell edge users through near users or relay networks in a multi-user scenario. However, the absence of a direct communication link between the base station (BS) and the cell edge URLLC user hugely degrades the reliability of data transmission and increases the chance of information leakage due to eavesdropping. Therefore, a coordinated direct and relayed transmission (CDRT) scheme is proposed for the CNOMA system to ensure the reliability and security of URLLC data transmission. A dedicated half duplex (HD) relay node is used to transmit an artificial noise (AN) signal along with the URLLC information intended for the cell edge user to confuse the eavesdroppers and decrease the information leakage. However, employing HD relay nodes in CNOMA may suffer from imperfect decoding and low throughput levels for legitimate users. Moreover, the large separation distance between the transmitter and the cell edge URLLC introduces challenges for ensuring the security and reliability of signal transmission. Therefore, the second contribution of the dissertation proposes an efficient PLS enhancement scheme for URLLC users at the cell edge by utilizing the CNOMA technique. An AN-assisted jamming, and full-duplex (FD) communication utilizing the near user to the BS as relay is proposed to improve the PLS of cell-edge URLLC users. The efficient resource optimization framework is proposed to improve the PLS performance for URLLC while managing the residual self-interference (RSI) at the FD relay and the intercept capabilities of the eavesdroppers. A large number of low-power IoT devices are deployed in an industrial IoT (IIoT) scenario where critical control information is exchanged among these devices in the form of short packets to facilitate URLLC. However, such confidential information transmission is vulnerable to information leakage and security threats due to the openness of wireless medium. Additionally, the presence of a large number of low-power devices in the system requires efficient utilization of system resources to achieve energy-efficient communication. Therefore, the third contribution of this dissertation is the development of an efficient PLS scheme for improving the secure energy efficiency of URLLC signal transmission in a multi-user and multi-eavesdropping scenario of the mission-critical IIoT application. The proposed PLS technique jointly optimizes the URLLC blocklength and pilot signal length to improve the secrecy throughput and optimizes the power allocation to ensure the secure energy efficiency of the system. In a large-scale IoT network ensuring the security of URLLC signal transmission is challenging because of centralized computing of confidential user information. To address this, the fourth direction of the dissertation is to propose efficient and secure decentralized computation of information using a Quantum-enhanced Federated Learning (QFL) framework to preserve the data privacy of edge URLLC users. The proposed QFL framework efficiently allocates the resources to ensure secure URLLC task offloading while managing the data heterogeneity in comparison to classical FL-based methods. Finally, the dissertation presents the concluding remarks on the research contributions and discusses the security challenges, enabling technologies, and future research directions for next-generation wireless service Hyper Reliable Low Latency Communication (HRLLC) in 6G
Data Driven Approaches using Statistical and Deep Learning Models for Time Series Analysis of Weather Data
No full textIn the realm of time series data prediction, especially in its application to meteorological data, time series analysis and forecasting are essential components of data science. It involves the development of models capable of accurately predicting future data points based on historical trends. In the context of weather prediction, the necessity for precise forecasting becomes apparent, as it plays a pivotal role in various real-world applications. In agriculture, precise predictions enable farmers to optimize planting and harvesting schedules, allocate resources efficiently, and enhance overall crop management. Energy utilities depend on weather forecasts to anticipate demand patterns, particularly in the realm of renewable energy sources. Transportation industries utilize forecasts for route planning, schedule optimization, and safety measures. Additionally, accurate weather predictions play a pivotal role in disaster preparedness, allowing governments and emergency services to proactively plan and respond to natural calamities, ultimately minimizing the potential impact on communities. The necessity of time series weather prediction extends beyond the immediate concerns of weather enthusiasts; it is an indispensable tool for informed decision-making across various sectors, contributing to the resilience and adaptability of societies in the face of dynamic environmental challenges. The fundamental requirements for effective time series prediction, encompassing data quality, feature engineering, and model selection. The significance of accurate weather predictions in mitigating risks, minimizing economic losses, and safeguarding lives underscores the direct impact of time series prediction on enhancing resilience in the face of dynamic environmental challenges. This thesis comprehensively explores the spectrum of time series forecasting methodologies, ranging from traditional univariate and multivariate statistical models to advanced techniques such as Vector Autoregressive - Gated Recurrent Unit (VAR-GRU), and Hybrid Deep Learning (DL) models such as channel attention based bidirectional GRU with Neural Basis Expansion Analysis for Time Series (ChAT-BiGRU-NBEATS) and self attention based bidirectional long-short-term memory with temporal convolution network (ABTCN) . The research delves into the theoretical underpinnings of univariate and multivariate statistical models, examining their strengths and limitations in capturing temporal dependencies. It subsequently transitions to the exploration of modern sequential modeling architectures, specifically VAR - GRU, which leverage the power of neural networks for enhanced predictive accuracy. The thesis further investigates the innovative realm of hybrid DL models, which amalgamate the strengths of diverse methodologies to achieve superior forecasting performance under missing and noisy data. The execution of each model has entails subjecting it to examination on benchmark data set. The methodological comparisons and empirical evaluations using performance evaluation parameter elucidate the efficacy of each approach, providing valuable insights for practitioners and researchers navigating the dynamic landscape of time series forecasting
Chitosan-based Bioactive Nanofibrous Hemostatic Agent for Emergency Care
No full textUncontrollable bleeding in major arteries has been reported to cause preventable 50% of battlefield casualties and 31% of mortalities in civilians worldwide. In India, road traffic injuries are a major concern, which causes 40% of deaths due to hemorrhage, and there is a rise of 2.4% every year. Commercially available hemostatic agents require at least 1-2 minutes for blood clotting, and most are either difficult to apply, expensive, or produce exothermic reaction upon contact with blood to cause adverse reactions. The objective of this study was therefore to investigate a novel self- assembly-based facile method to fabricate chitosan-casein/gelatin nanofibers through polyelectrolyte complex (PEC) formation for rapid hemostasis. The efficacy of hemostasis was improved by optimizing the process parameters and incorporating biologically active nanoparticles to nanofibrous PECs. The also investigated the effect of nanoparticles (e.g., ZnO-NP, AgNP) on improving bioactivity of the chitosan-based nanofibrous PEC under in vitro and in vivo conditions. FTIR spectroscopy revealed that amide group (1630 cm-1) of chitosan and phosphate group (910 cm-1) of casein could form nanofibrous PEC with electrostatic interaction at pH 8.2±0.2. The chitosan and casein in the ratio of 30:70 (CC30), 50:50 (CC50), and 70:30 (CC70) nanofibrous PECs allowed platelet adhesion and rapidly absorbed blood fluid to form rapid blood clots within 9±3, 16±3, and 30±4 s, respectively, which were better than commercially available Celox™ (90±3s). Increasing the concentration of chitosan from 10% to 90% in the CC formulations increased the productivity (r=0.99) of PECs but led to increased blood clotting time (r=0.90) due to an increase in zeta potential (r=0.98), fiber diameter (r=0.93), and decreased surface porosity (r=- 0.99), absorption capacity (r=-0.99). The pH also influenced zeta potential of PEC, with an optimized pH of 8.0±0.1 yielding clear nanofibers. Sonication improved the segregation of nanofibers by promoting water removal. The optimized PECs containing chitosan and casein in ratio of 30:70 (CC30) at a pH of 8.0 and dehydration under sonication could clot the blood within 9±2s in vitro and 9±2s in rat femoral artery puncture model with no evidence of rebleeding. The CC-based nanofibrous PEC were highly hemocompatible, biocompatible, non-toxic, and non- immunogenic. The chitosan-casein PECs could also be developed as microporous hemostatic sponge (CC30G) with porosity of 73.00±4.74%, pore diameter of 42.66±5.33 μm, and rapid water absorption capacity (1165±55%). The CC30G sponge showed bacteriostatic action against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Upon incorporation of AgNP, the sponge (CC30GS) acquired the bactericidal property. The sponge could also be combined with adhesive tape to develop as a hemostatic band-aid for bleeding in skin lacerations, cuts, and topical wounds. Bioactivity of CC-based PECs (CC30Z) could be improved by incorporation of ZnO-NPs without compromising their hemostatic efficiency or biocompatibility. ZnO-NP incorporated PECs (CC30Z) were bioactive in terms of their bactericidal effect against Gram-positive S. aureus and Gram-negative E. coli, promoting cellular metabolic enzyme activity (alkaline phosphatase, glutamate dehydrogenase, lactate dehydrogenase, and malate dehydrogenase) for skin regeneration, and enhanced platelet aggregation and activation for rapid hemostasis. Results further showed that replacing casein with gelatin in the chitosan-based PECs could also increase the compressive elastic modulus of PEC-induced blood clots from 21±2 kPa to 68.6 ± 6.4 kPa, which was five-fold better than a commercially available CeloxTM-induced blood clot. Ag-NP (CG30S) and ZnO-NP (CG30Z) incorporation in chitosan-gelatin PEC did not affect the fiber diameter, surface porosity, hemocompatibility, and biocompatibility of the chitosan-gelatin PECs nanofibers but had bactericidal effect on both Gram-positive S. aureus and Gram-negative E. coli. Both CG30S and CG30Z could clot the blood within 10 s under in vitro conditions and rat femoral artery puncture model in vivo. Further, CG30Z had excellent bioactivity in promoting cellular/tissue metabolic enzymes involved in skin regeneration and could enhance platelet aggregation as well as activation. Taken together, chitosan-casein/gelatin nanofibrous PEC could rapidly clot the blood with 10 s under in vitro conditions by promoting platelet activation and aggregation, rapid absorption of plasma, and activation of extrinsic coagulation pathway. It could also clot blood within 10 s in rat femoral artery puncture model and within 25s in rabbit ear artery model. The PEC was bioactive, bactericidal, hemocompatible, biocompatible, non-toxic, non-immunogenic and safe for use in animal models. The chitosan-based PECs could also be developed as hemostatic sponge for skin cuts and lacerations. Further pre-clinical trials on large animals should be conducted under GLP conditions before clinical trials in humans for a successful market-ready product
Development of Process for Improving Functionality of Little Millet Flour using Cold Plasma
No full textThe abundant production of little millet in India and having rich nutritional profile, prompting a need for scientific interventions to optimize its utility compare to other primary cereal crops. This study investigates the effects of cold plasma on the functionality of little millet flour (LMF) for value addition. LMF was treated at applied voltages of 10 and 20 kV with treatment times of 10, 20, and 30 min. Functional characteristics such as oil absorption capacity, water absorption capacity, swelling capacity, and solubility index were enhanced significantly (p˂0.05) by plasma treatment from 1.10 to 1.35 g/g, 1.34 to 1.51 g/g, 2.92 to 4.23 g/g and 0.054 to 0.085 g/g respectively, while physical properties such as bulk density, dispersibility remained unchanged and not significant. Microstructural analysis showed starch granule breakdown, and X-ray diffraction indicated decreased crystallinity from 47.98 % to 43.97% due to starch depolymerization by reactive oxygen and nitrogen species. Rheological studies using varying voltages (10 – 20 kV) and durations (10, 20 & 30 min) demonstrated that plasma-treated LMF exhibited improved storage and loss moduli and pseudoplastic behavior, fitting the Herschel-Bulkley model with R2>0.99. Comparison studies such as functional rheological properties conducted between direct plasma and plasma activated water treatment. Enhanced functional characteristics, particularly in samples treated with multipin cold plasma at 15 kV for 30 min. Plasma treatment also enhanced total phenolic content and antioxidant activity significantly (p˂0.05) from 527.54 ± 8.94 to 575.82 ± 3.58 mg gallic acid equivalent /100 g, and 14.39±0.77 to 22.94± 1.84% respectively. On other hand, anti-nutritional factors like tannins and saponins (226.96±27.54 to 135.65 ± 2.90 mg tannic acid/100 g of d.m and 454.33±50.75 to 190.15±35.82 mg diosgenin/100 g of d.m) were reduced and significantly differed at p˂0.05. Besides moisture, ash and fat content of millet flour didn’t have significant difference for all treated voltage and times. However, protein, carbohydrate contents were increased with a rise in applied voltage and treatment time. The optimized conditions for all properties was obtained at 20 kV and 20 min. Accelerated storage studies were conducted at 40ºC & 90% RH, the treated flour had a shelf life of 2.52 months in high density polyethylene (HDPE) and 0.77 months in low density polyethylene (LDPE) packaging, while the untreated flour had a shelf life of 2.45 months in HDPE and 0.75 months in LDPE. Pasta was prepared by incorporating of 10% and 20% LMF with and without plasma treatment. Color parameters, such as the L-value and whiteness index, were improved in the treated pasta samples and close to control. Optimal cooking time was decreased in treated pasta than untreated pasta samples. Instrumental analysis such as infrared spectra, diffractograms, thermographs and micrographs were analyzed. These results highlight the potential of plasma treatment to enhance the functionality and rheological parameters of LMF, suggesting its application in diverse food products
Bone Morphogenetic Protein – 2: Mechanistic Insights into Unfolding and Aggregation and Biomedical Applications
No full textThe unfolding kinetics of BMP-2 in the presence of extracellular components such as hyaluronic acid (HA) and sulfated hyaluronic acid (SHA) were meticulously investigated, revealing a higher rate of unfolding in the SHA environment. This accelerated unfolding is likely attributed to the binding interaction between SHA and the partially unfolded protein, which further promotes the unfolding process. In subsequent thermal denaturation studies, SHA was identified as a stabilizer at lower temperatures, while HA exhibited a stabilizing effect at elevated temperatures. The aggregation propensity of BMP-2 was examined under both HA and SHA conditions, with distinct aggregation mechanisms observed. While both GAGs induced aggregation, SHA primarily facilitated the formation of rapid, amorphous aggregates, whereas HA promoted the development of amyloid fibrils, characterized by a lag phase and sigmoidal kinetics. The size and morphology of these aggregates varied significantly; HA led to the formation of larger fibrillar structures, whereas SHA generated smaller, amorphous aggregates. The aggregation pathways were influenced by factors such as viscosity and excluded volume. Specifically, the higher viscosity and reduced protein diffusivity in the presence of HA, along with increased excluded volume, favored the formation of fibrils in the micrometer range. In contrast, the lower viscosity and higher diffusivity of BMP-2 in the SHA environment, coupled with reduced excluded volume, promoted the formation of amorphous aggregates in the nanometer range. To counteract this aggregation, disaggregation strategies utilizing ammonium-based ionic liquids were explored. Small alkyl chain ionic liquids proved most effective in promoting the disaggregation of BMP-2. The intrinsic propensity of BMP-2 for aggregation and unfolding was harnessed to develop a hydrogel, which was mediated through controlled protein unfolding. This hydrogel exhibited excellent biocompatibility and demonstrated significant potential for wound healing applications, particularly in Drosophila melanogaster
Performance Assessment of Futuristic Novel TFET Architectures for Ternary CMOS and Biosensor Applications
No full textWith the advancement of the electronics industry, there is a growing need for increased integration levels and cost-effective technologies. With the constant downscaling of CMOS technology, high-speed MOS devices have been developed that are ideal for analog/RF applications. It is crucial to have systems that prioritize low distortion and linearity as fundamental components of their design. But nowadays, due to the downscaling, the CMOS technology faces many challenges regarding short-channel effects (SCEs). So, this resulted in requirement for new device architecture and design. One prospective candidate for enhancing the performance of scaled CMOS integrated circuits is a tunnel field effect transistor (TFET). TFET functions through the mechanism of band-to-band tunneling (BTBT), which can obtain low OFF current (IOFF), steep subthreshold swing (SS), and high ION/IOFF ratio at reduced supply voltage but has low ON current (ION), and ambipolar conduction occurs. TFET can be used for many low-power applications. The performance improves when we increase the control over the channel. So, the double gate TFET (DGTFET) outperforms single gate TFET. Different DGTFET structures have been modeled and simulated with SiO2/high-k stacked gate oxide. The work function and pocket engineering also help to enhance the device's performance. In modified gate oxide double gate TFET (MGO DGTFET), the gate oxide is carefully placed at an optimized depth within the channel, leading to decrease in IOFF and ambipolar current. There is enhancement in ION; eventually, ION/IOFF ratio improves. In triple metal extended source double gate vertical TFET (TM-ES-DGVTFET), the channel is perpendicular to the source, which increments the probability of lateral and vertical tunneling. As a result, there is an enhancement in ION, SS, and ION/IOFF ratio. Different applications of TFET have also been investigated. A vertical TFET with a pocket (VP-TFET) has been used to design a ternary inverter. In VP- TFET a thin silicon epitaxial layer is present between the source and gate oxide. P+ pocket is present in channel close to source region. In VP-TFET vertical tunneling occurs along with lateral tunneling. A hump is created at the channel region because of the presence of a P+ pocket in the channel. In VP-TFET channel-channel and source-channel tunneling occurs and a ternary inverter has been designed. The ternary inverter is a multi-valued logic (MVL). MVL helps to reduce power density on a chip. Ternary logic, which has three steady states ("0", "1", and "2") instead of binary logic, which has two states ("0", and "1"), may store more data in the same amount of space. This directly correlates to miniature chip size and helps reduce the total number of interconnects and pins used in a VLSI chip design. TFET-based ternary logic can be advantageous in spiking neural networks and neuromorphic computing. A vertical TFET has been used to detect the biomolecules. In vertical TFET-based biosensor (VB) a thin silicon epitaxial layer is present between the source and gate oxide. The cavity is etched beneath the gate electrode at the left side of HfO2 for biomolecule immobilization. The dielectric constant is altered by the immobilization of biomolecules within the carved cavities, which were formerly filled with air. This modification changes device's electrical characteristics. In VB, vertical and lateral tunneling occurs, which increases the tunneling carriers, the current increases, and eventually, the sensitivity of the biosensor is enhanced. The Poc-MGOTFET-based biosensor is used to detect breast cancer (BC) cell lines. The gate oxide of Poc-MGOTFET-based biosensor is carefully placed at an optimized depth within the channel. The SiO2 layer within the nanogap cavity serves as an adhesive layer for the cell lines. The N+ pocket is incorporated at the source side and the gate is an extended structure. The cavity is etched beneath the gate electrode at the left side of HfO2 for biomolecule immobilization. Breast tissue included healthy (MCF-10A) and cancerous (MCF-7, T47D, Hs578T, and MDA-MB-231) cell lines. The detection method of the biosensor is based on differences in the dielectric constants of different BC cell types. The dielectric constant is altered by immobilizing the cancer cells within the carved cavities, formerly filled with air. This modification changes the device's electrical characteristics. Sensitivity analysis considers drain current, transconductance, ION/IOFF ratio, and VT. Maximum sensitivity is observed in T47D (k = 32) BC cells because it has a higher dielectric constant. The selectivity is calculated between the healthy and cancerous BC cell lines. The effect of irregular cell line confined in the cavity has been investigated to evaluate the ability of the device to detect BC cell lines. The Poc-MGOTFET-based biosensor can detect breast cancer biomarker (C-erb-B-2). The effective charge caused by the existence of C-erbB-2 biomarker in serum/saliva is utilized as the interfacial charge of the device for detecting C-erbB-2 biomarker. Sensitivity analysis considered ION/IOFF ratio. The significant increase in sensitivity, by a factor of 106 μg/L, is attributed to the influence of interfacial charges caused by different C-erbB-2 biomarker quantities on biosensor's sensitivity (as determined by ION/IOFF ratio)
Development of Ni-based Hybrid Coatings by Electrodeposition/ Laser Cladding Followed by Ultrasonic Shot Peening
No full textThe ultrasonic shot peening (USSP) technique is a reliable post-treatment method for various industrial components to prevent functional failures by imparting residual compressive stresses, texturing, roughness modification, surface nano-crystallization, and compaction. This study aims to develop hybrid Ni-based coatings and cladding on mild steel using Electrodeposition/laser cladding (LC) and USSP techniques. Morphological studies reveal that the coatings and claddings exhibit enhanced closure of pores/cracks, increased micro-hardness, and improved corrosion and scratch resistance after peening. XRD analysis confirms the presence of compressive residual stresses, as well as grain refinement and texturing effects after the peening. After undergoing USSP treatment, the average surface roughness increased by up to 6 μm due to the formation of dimples. Furthermore, compared to the Ni/Ni-TiO2/Ni-Cr coatings and claddings, the hybrid coatings exhibit a hydrophobic character linked to improved corrosion resistance and better in-depth roughness profiles. Furthermore, the research endeavors to improve their mechanical and electrochemical properties by employing USSP's varied process parameters in a hybrid approach
Design and Development of a Pre-Cooler Cum Disinfection Based Green Cold Storage Unit for Perishable Agricultural Commodities
No full textFruits and vegetables (F&Vs) are highly perishable and prone to microbial spoilage and quality degradation, largely due to inefficient storage methods, leading to significant losses. Most F&V storage systems do not have disinfection facilities and are entirely dependent on grid electricity or partially dependent on solar energy, which provides energy only during daylight hours. In the existing solar cold storage systems, electric batteries are often used to provide backup power during night-time, which increases the operating cost of the F&V storage system. Hence, there is a need to develop proper methods and equipment for effective disinfection and storage systems for F&Vs. In this study, operation, i.e., pre- cooling, disinfection, and low-temperature storage unit are designed and developed for preservation and shelf-life enhancement during storage, utilizing solar energy as its power source. Various physical, textural, thermal and quality analyses of amla (Phyllanthus emblica) fruit were investigated for designing the system. The bulk and true density of amla fruit were 661 and 1044 kg/m3, while thermal properties such as specific heat and thermal conductivity were 3.73 kJ/kg°C and 0.55 W/m°C, respectively. The physiochemical properties of amla fruits significantly changed during post-harvest storage. These quality changes were related to moisture and weight loss and decreased intercellular space in the microstructure. The equipment is designed using CATIA V5 software as a portable machine for all types of F&V preservation. The equipment is fabricated with stainless steel (SS304L) for fruit contact parts and mild steel for the support structure of the equipment. The equipment consists of a pre-cooling cum disinfection system, low-temperature storage units, and a cold thermal energy storage system that stores cold energy uses during night-time or in the absence of solar energy. The developed system was tested on two different types of fresh produce: amla and tomato (Solanum lycopersicum). Both samples were independently tested in a developed pre-cooler cum disinfection unit (ozone-assisted hydrocooling). Ozone-assisted hydrocooling (OAHC) treatment was carried out by incorporating the ozone gas with the hydrocooling process. Different ozone concentrations were dissolved into hydrocooled water and presented no negative impact on the cooling rate, microstructure, and quality of fresh produce during testing of precooling cum disinfection system. It was also found that precooling cum disinfection treatment effectively reduced the Escherichia coli (E. coli) count by 2 and 3 log reductions from tomato and amla, respectively. In addition, E. coli inactivation was increased significantly (p<0.05) with increasing ozone concentration. Scanning electron microscope (SEM) images confirmed that OAHC did not alter the microstructure of amla and tomato during pre-cooling. More importantly, OAHC retarded the quality degradation of amla and tomato during storage. Moreover, it was observed that the ascorbic acid, weight loss, firmness, and TPC were significantly (p<0.05) higher in OAHC-treated samples compared to cold room cooled samples during storage. Ozone integration with the hydro cooling process emerges as a green technology for disinfection and precooling of fresh produce without adversely affecting its quality characteristics. The cost economic analysis of the developed system was carried out and reported that the unit cost of a machine was ₹450000, with a cost-benefit ratio of 2.99 and a payback period of 0.33. The equipment developed is considered to be economically and commercially feasible for farmers and small and medium-scale industries
Development of Sodium Alginate/chitosan Based Nano-composite Three-dimensional Printed Scaffolds for Bone Tissue Regeneration
No full textA functionalized scaffold with desired physico-chemical, structural and biological characteristics is a pre-requisite to regenerate damaged bone tissue. The present work aimed to develop sodium alginate (SA) and chitosan (CH) based nano-composite scaffold by three- dimensional (3D) printing technique for bone tissue engineering (BTE). To this end, 3D printed SA/CH blend scaffolds with different compositions were fabricated. The scaffolds possess open pore microstructures and interconnected pores with appropriate pore size as evident from scanning electron microscopic image analysis. The Fourier-transform-infrared spectroscopic analysis revealed polyelectrolyte complex (PEC) formation when SA and CH were blended, that can provide superior scaffold surface for cell attachment, proliferation, and offers ideal microenvironment for neo tissue formation. Among the scaffolds, SA/CH with 60:40 ratio exhibited controlled swelling and degradation pattern, higher tensile strength (0.387 ± 0.015 MPa) and superior apatite layer deposition ability. The scaffolds are hydrophilic and biocompatible as evident from contact angle, protein adsorption, MTT and cell attachment assessment. Thus, the developed 3D printed scaffold with SA/CH (60/40) is proven to be a suitable substrate for tissue engineering application. The biological property of the SA/CH scaffold was improved by blending with 0-15% (v/v) gelatin (GE) thereby promotes cell adhesion, proliferation and differentiation. The resulting tri-polymer complex was used to fabricate 3D printed SA/CH/GE matrices. The microfibrous porous scaffolds having 383-419μm pore size were revealed by SEM study. X- ray diffraction (XRD) and FTIR analyses confirmed their amorphous nature and the strong electrostatic interactions among the polymer functional groups forming polyelectrolyte complexes that may improve mechanical property and structural stability during in vivo application. The scaffolds have controlled swelling and degradation pattern, hydrophilic characteristics favorable for bone tissue regeneration. An enhanced tensile strength was obtained due to increased stiffness of SA/CH scaffolds upon addition of GE. An enhanced protein adsorption and apatite layer formation confirmed the ability of SA/CH/GE scaffolds for higher cellular adhesion and bone like environment during tissue regeneration process. MTT assay, and confocal microscopy analysis exposed a significant enhancement in cell adhesion, metabolic activity, proliferation and biomineralization activity. Furthermore, SA/CH containing 15% GE (SA/CH/GE15) has shown superior performance indicating their suitability for bone tissue engineering application. For the improvement of osteogenic property, Bioglass (Bg) and nMgO-loaded Bg nanoparticles were synthesized and characterised. The synthesized nBg was further introduced into SA/CH/GE15 polymeric network to achieve natural bone mimetic property containing the desired inorganic and organic phase. The osteogenic and other cell supportive property of the SA/CH/GE15 scaffold were enhanced by reinforcing nBg with different concentration (0.3%- 0.5 %w/v) in the polymeric network resulting in composite bioinks which were used to fabricate 3D printed SA/CH/GE15/nBg. The nano-composite scaffold have microfibrous open pore structure with pore size range of 419±102μm to 554±68 μm. The hydrophilicity of the scaffold was improved on addition of nBg with decrease in contact angle. The scaffolds exhibited controlled swelling and degradation behavior desired for BTE and enhanced compressive strength with increased nBg content in the SA/CH/GE15 scaffold and the values were 1324.63±32.71 kPa and 1942.33±37.56 kPa for SA/CH/GE15/nBg0.4 and SA/CH/GE15/nBg0.5 which are desired for cancellous bone regeneration. An enhanced bioactivity and protein adsorption was achieved with nBg incorporated scaffolds. MTT assay with cultured bone osteosarcoma cells on the composite scaffolds showed that SA/CH/GE15/nBg scaffolds are cytocompatible. An improved cell supportive activity (cell attachment and proliferation) was shown by nBg loaded scaffold as evident from SEM and confocal image analysis. In comparison, a higher ALP activity representing higher osteogenic property was shown by SA/CH/GE15 containing nBg0.4. The effect of reinforcement of the synthesized nMgBg in the SA/CH/GE15 network on the osteogenic ability of the 3D printed scaffold was investigated. The reinforcement of nMgBg at 0.4% and 0.5% w/v concentration with SA/CH/GE15 polymeric network did not affect the hydrophilicity, swelling, degradation and protein adsorption activity of the scaffold. The presence of Mg promoted apatite layer formation over the scaffold as revealed by in-vitro bioactivity test and SA/CH/GE15 nMg1Bg0.4 showed the highest apatite formation. In-vitro cell studies suggested that low Mg containing scaffolds SA/CH/GE15/nMg1Bg0.4 is favorable for osteoblast proliferation. The scaffold showed superior ALP and biomineralization activity than the scaffolds containing nBg and nMg2Bg. Overall, SA/CH/GE15/nMg1Bg0.4 was demonstrated as the most potential substrate that can pave the way for bone tissue regeneration in future