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Synthetic Efforts Towards Carbon-Heteroatom Bond Generations Employing Dearomatization, Alkene and Alkyne Intrigues
No full textCarbon-hetero bond generation has been a core interest of synthetic chemists throughout the past. The modern approach to develop these attempts in environmentally benign condition with atom economy has emerged as a frontier goal in organic synthesis. Particularly, dearomatization of cheaply available planar arenes and molecular gymnastics with alkenes and alkynes precursors has opened a new avenue for chemists with regard to efficiency and versatility. The present thesis covers some of our attempts in the generation of carbon-heteroatom bonds via dearomatization of planar phenols and pyridine derivatives in the first part, delivering the multi-functionalized spiro, indolizine molecules employing our own tri-bromides (TBrs), visible light and copper(I) catalysis. The second part of the thesis focuses on strategies like isomerisations of alkenes or alkynes, free radical reactions and multi-component reactions to synthesize these biologically important motifs.
Chapter-I:
In this chapter, we have discussed a metal free one-pot stereoselective synthesis of para-quinone monoketals and their derivatives have been reported in this present work. Tri-bromides (TBrs) have been employed as an effective reagent for intramolecular spiro-cyclizations leading to excellent yields of the monoketals. The TBrs are slowly turning out to be an important reagent for oxidative dearomatization which is further attested in the presented work. In addition, the obtained substituted para-quinone monoketals and their derivatives were readily transformed into more complex products by reaction with Pd/C under hydrogen atmosphere leading to saturated para-monoacetal, which are important building blocks in organic synthesis.
Chapter-II:
In this chapter, we metal free one pot approach towards a highly stereoselective synthesis of N-substituted spiro azacyclodienones, dihydro spiro-azacyclodienones and spiro-lactams has been reported in this present work. Phenyl tri-methyl ammonium tri-bromide (PTAB) as an effective reagent has been implied for intramolecular spiro-cyclizations via the key oxidative dearomatization reaction. Interestingly, the obtained substituted N-substituted spiro azacyclodienones was readily transformed into strained cyclopropanated spirocycles.
Chapter-III:
In this chapter, a visible light assisted dearomative selenylative carbo-spirocyclisation of aromatic homologated-ynones has been reported. The ynones deliver selenylative spiro-cyclohexadienones and spiro-diepoxides at varied temperatures. The prescribed methodology is photo-catalyst free and scalable. The combination of visible light, molecular oxygen and the products synthesized delivers a uniqueness to the designed methodology.
Chapter-IV:
In this chapter, we have discussed an efficient two-component copper-catalyzed cyclization cascade approach towards highly functionalized indolizinone heterocycles have been developed from reactions of pyridine-, isoquinoline-, and quinoline ynones, via 5-exo-dig cyclization. The catalysis involves the activation by diorgano diselenide and diorgano disulphide and also their incorporation into the indolizinone core. In addition, the obtained substituted indolizinones were readily transformed into 1 (organochalcogenyl)indolizin-2-ols, which are important building blocks in organic synthesis.
Chapter-V:
In this chapter, we have discussed the radical induced cyclopropyl ring fragmentation with encompassed olefinic and cyclopropane environment has been carried out. Interestingly, the fragmentation has occasioned onto a stereoselective synthesis of trans-3-allyl-2,3 dihydrobenzofurans (TADHBs) with impressive yields. The trans-dihydrobenzofurans are present as central core in many molecules of medicinal interest and the present protocol deliver a straight forward access to the embedded molecular architecture.
Chapter-VI:
In this chapter, we have discussed about an efficient approach for the synthesis of α-allyl α-selanyl ketone and selanyl tetra-hydrofurans has been reported in this present work. The sodium methoxide (MeONa) mediated one pot three-component synthesis lead towards a good to an excellent yield of products with a wide substrate scope. The selenylated ketones can be important point towards important organic synthons.
Chapter-VII:
In this chapter, we have discussed about a facile hydrochloride promoted regioslective synthesis of isoxazoles and pyrazoles from 1,2-allenic ketones. The reaction has been scaled upto grams. A direct 8-endo-dig ring annulations towards the first synthesis of (Z)-2-methyl-7H benzo[b]pyrazolo[5,1-d][1,5]oxazocine has been developed.
Chapter-VIII:
In this chapter, we have discussed about revisit towards regioselective addition of insitu generated negative nucleophiles to allenic ketones in the presence of a base. A wide variety of allenic ketones as well as nucleophiles are viable in this transformation. A direct ring annulation towards the challenging benzodioxin skeleton synthesis has been developed. Environmentally benign protocol and wide substrate scope are the notable features of this methodology.
Chapter-IX:
In this chapter, we have discussed about addition of boron trifluoride etherate (BF3OEt2) to allenic ketones has lead to trapping of the isolated boron-difluoride enolate. The challenging single-crystal structure of the boron-enolate has been solved. The (Z) β-difluoroboryloxy ether derivatives undergo an unpreceedented C1-C10 migration, to deliver rearranged phenol derivatives which are functionalized to C-2 alkyl-chromenones. This has been the first example where isolated boron-enolates have exhibited significant anti-cancer properties.
Chapter-X:
In this chapter, we have discussed about an efficient copper-catalyzed cyclization cascade approach towards highly functionalized methylene 4-chromanol and aurone derivatives has been developed from reactions of ynols via 6-exo-dig and 5-exo-dig cyclization respectively. The catalysis involves the alkyne activation via diorgano-diselenides and also their regioselective incorporation into the methylene 4 chromanol and aurone derivatives core and is an open-air transformation.
Chapter-XI:
In this chapter, we have discussed about a direct metal-free approach for the synthesis of alpha-cyanoalkylboronic esters from bis-diboron ester and azobis-nitrile compound is reported under ambient temperature and pressure via a free radical procedure
Analysis of Pulse Tube Refrigerator using CFD
No full textThe present thesis is a detail endeavors of numerical investigation of an Inertance pulse tube refrigerator(IPTR) and Gifford-McMahon (GM) pulse tube followed by corresponding optimization of various geometrical and operating parameters including demonstration of a novel modification in existing GM pulse tube know how by proposing a piston arrangement on the double inlet connecting pipe.
To start with, a benchmark IPTR model has been analyzed numerically using 2Daxisymmetric model followed by 3D assembly. Subsequently, the parametric optimizations have been carried out to estimate the optimal operating and geometrical parameters, independently followed by in combination, which recommends an optimal IPTR having lowest temperature approximately 22% lower than the initial IPTR under investigation.
Next, a benchmark GM pulse tube, which had been experimentally investigated, has been taken for numerical investigation, where the demonstrated numerical result agrees to experimental result adequately, however, a novel numerical scheme based on user define function (UDF) and a sinusoidal temperature profile has been proposed, which reduces the computational overhead significantly and permits to optimize the valve openings, where the observed temperature at cold heat exchanger becomes approximately half with respect to initial one.
At last, a novel concept has been proposed to enhance the performance of a GM pulse tube by introducing a frictionless piston on the path of double inlet connecting pipe. The
conceptual proof has been investigated using fluid structure interaction, which is first in its own domain, where the lowest temperature at CHX has been observed to be 23.8 K
Solving Molecular Complexities with Oxidative Dearomatisation and Transition Metal Catalysis
No full textControlled generation of multifunctionalized and biologically important compounds from simple starting materials is one of the sincere challenges for any organic chemist.With the continuation to the recent trends, the proposed research work was designed to synthesize biologically active core molecules employing oxidative dearomatisation and transition metal catalysis. Dearomatisation of aromatics has been considered to be the best and most powerful approach towards the synthesis of complex molecules. Many groups have been putting serious efforts on dearomatisation from years albeit, spiro-oxacycle synthesis has been a less explored direction. The thesis chapter highlights the transformation of planar phenols, naphthol and pyridine derivatives into multifunctionalised spiro and pyridone molecules employing Phenyl Trimethylammonium Tribromides (PTAB) and ruthenium catalysis. Heterocyclic motifs have been important point of attraction due to their demanded biological activity and pharmaceutical importance. The thesis is divided into the following five chapters
Chapter-I describes a new methodology for spirocyclisation of planar phenols and naphthols employing Phenyl Selenium Bromide (PhSeBr) and Phenyl Trimethyl Ammonium Tribromide (PTAB) into 3D framework. The work recognizes PTAB and PhSeBr as an effective reagent for dearomatisation. A generalised economical route for the synthesis of a wide variety of spiro-oxacycles from planar naphthols and phenols is achieved. Diastereoselective generation of oxa-spirodieneones, overall fantastic yields, a rich substrate scope, and mild conditions along with the economy involved makeing this a sustainable methodology. Importantly this work also reveals no side reactions like polymerization which are commonly observed in dearomatisation reactions and thus makes it a reliable solution.
Chapter-II describes the metal-free synthesis of benzofurans and naphthofurans employing Phenyl Trimethyl Ammonium Tribromides. Benzoaxacycles like benzofurans and naphthofurans are an important scaffolds present in many biologically and medicinally important natural products.
Chapter-III describes a lucrative Ru (VIII) catalyzed spiro-etherification and spiro-amidation of phenols. An open air ruthenium (VIII) catalysed oxidative spiro-etherification as well as spiro-amidation of phenols has been accomplished. The transformation works satisfactorily with both phenols and naphthols and thus exhibit a wide range of flexibility. The catalysis is executed in open air and room temperature condition with an improved yield achieved upto 95%.
Chapter-IV describes an extension of the feasible methodology described in chapter (III) and describes the Ru (VIII) catalyzed dearomatisation of pyridines. The synthesis is carried out in open air condition, and the products obtained are N-protected pyridones, which have been immensely useful synthetic motifs.
Chapter-V describes the synthesis of trisubstituted nicitonitriles. A de novo palladium carboncatalyzed
synthesis of trisubstituted nicotinonitriles from easily synthesized homopropagylic or homoallylic aromatic alcohols in the presence of nitriles has been explored.The mechanism
proceeds with an interesting generation of a Pd (II)-C palladacycle followed by an oxidative aromatization to generate the pyridine core. The pyridine core is generated with a noteworthy C−C bond cleavage in the case of the substituted nitriles.The moderate yields and easy separation of the products lend a unique importance to this one-pot methodology
Estimation and Forecasting of Suspended Sediment Yield in Mahanadi River Basin: Application of Artificial Intelligence Algorithms
No full textRivers are dynamic geologic agents on earth and act as the main pathways for transport of continental materials to the ocean. Estimation and forecasting of suspended sediment yield (SSY) are essential towards understanding the mass balance between the ocean and land. The volume of SSY transported in a river provides important information about its morphodynamics, the hydrology of its drainage basin, and the erosion and sediment delivery processes operating within that basin. Estimation and forecasting of SSY is always a key factor during the evaluation of reservoir project, protection of fish and wildlife habitats, understanding of flood capacity, hydroelectric equipment longevity, planning and management of any river system. The SSY depends on number of variables and their inter-relationships which are highly nonlinear and complex in nature. Direct measurement of SSY is difficult and needs sufficient time and money. Additionally, it is difficult to estimation and forecasting of the SSY by using traditional mathematical models because they are incapable to handle the complex non-linearity and non-stationarity process. Thus, the aim of this study is to develop hybrid simple genetic algorithm based artificial neural network (GA-ANN) and genetic algorithm based multi objective optimization with artificial neural network (GA-MOO-ANN) models to estimate and forecast the SSY at eleven locations in the Mahanadi river basin, which is one of the largest rivers in India. All parameters associated with the models are optimized simultaneously using simple genetic algorithm and multi-objective genetic algorithm for estimation and forecasting of the SSY. Temporal information of monthly rainfall, temperature, water discharge, and suspended sediment yield during 1990-2010 along with rock type, relief and catchment area are used at all eleven gauging stations in Mahanadi river for the development of models. It is observed that water discharge and SSY show wide fluctuations whereas temperature and rainfall do not show much variation among different gauge stations in the basin. The performances of GA-MOO-ANN and GA-ANN models were compared to traditional artificial neural network (ANN), multiple linear regression (MLR), auto regressive (AR), multi variate auto regressive (MAR) and sediment rating curve (SRC) method for evaluating the estimation and forecasting capability of models on testing data set. The results suggested that the hybrid GA-MOO-ANN and GA-ANN models exhibited satisfactory performance and provided better results than the traditional ANN, MLR, AR and MAR models. The models are unable to estimate and forecast the SSY at gauge stations having very small catchment areas whereas performing satisfactory on locations having moderate to large catchment area. The models provide the best result at Tikarapara, the gauge station location in the extreme downstream, having the largest catchment area. If measurements of suspended sediment are not available in any river then the modelling approach can be potentially used for the estimation and forecasting of SSY at gauge or ungagged locations
Image Denoising by Edge Preserved Curvelet Thresholding
No full textThe limitations of imaging systems invariably add an undesirable component to the digital image referred as noise. Since modifying the imaging system is not always possible, denoising methods become an essential pre-processing step for many image processing applications. This thesis presents three novel contributions to the field of image denoising, while considering the phase as an indispensable component for restoration.
Phases Under AWGN: The phase of complex transforms like Fourier, Complex wavelet and Curvelet, of an image is more immune to noise than its magnitude. This thesis analyzes its immunity to additive white Gaussian noise (AWGN) both mathematically and quantitatively. We have derived noise sensitivity i.e. the rate of change of noisy image phase or magnitude with respect to AWGN magnitude. The results indicate that the magnitude of these transforms deteriorates faster than that of phase with increasing noise strength, while the Curvelet phase becomes more immune to noise compared with other transforms.
Denoising by Preserving the Phase: Denoising via Curvelet thresholding removes the coefficients below a threshold and loses signal residual in noise subspace. In effect, it produces ringing artifacts near edges. We found, the noise sensitivity of Curvelet phase – in contrast to its magnitude – reduces with the higher noise level. Thus, the magnitude of the coefficients below the threshold is estimated using Wiener filter (and joint bilateral filter in another method) at each scale and corresponding phase is preserved to recover the signal residual. We apply the Bilateral Filter (BF) at the finest scales to preserve the edges without any discontinuity. Further to reduce the ringing artifacts and to preserve efficiently the local structures like: edges, texturesand small details, the (Curvelet based) reconstructed image is post processed using the Guided Image Filter (GIF). The proposed method is tested on both artificial and natural images to prove its efficacy for denoising.
Denoising by Multi-Scale Hybrid Approach: This thesis presents another image denoising technique using a multiscale Non-Local Means (NLM) filtering combined with hard thresholding in the Curvelet domain. The inevitable ringing artifacts in the reconstructed image – due to thresholding – is further processed using GIF for better preservation of local structures like: edges, textures and small details. We decomposed the image into three different Curvelet scales including the approximation and the fine scale. The low frequency noise in the approximation sub-band and the edges with small textural details in the fine scale are processed independently using multiscale NLM filter. On the other hand, the hard thresholding in the remaining coarser scale is applied to separate the signal and the noise subspace. Experimental results on both grayscale and colour images indicate that the proposed approach is competitive at lower noise strength with respect to Peak Signal to Noise (PSNR) and Structural Similarity Index Measure (SSIM) measure and excels in performance at higher noise strength compared to several state-of-the-art algorithms
Dynamics and Control Simulations of Turbocharger Rotor-Bearing Systems
No full textIn the current global scenario, automotive industries struggle for fuel consumption and emission reductions, while constantly improving the engine power output and performance. These require turbocharger units which make easy long maintenance intervals along with improved reliability and efficiency. A Turbocharger basically consists of a radial inflow turbine, a centrifugal compressor and a central housing of rotating assembly. The present work focuses on the modelling and dynamic analysis of the turbocharger rotor supported on floating ring and foil bearings for parametric identification, stability analysis and vibration reduction aspects. The flexible rotor-bearing system is modelled using the finite element approach and the nonlinear dynamic responses due to unbalance and aerodynamic loads are obtained. Numerical and experimental modal analysis is performed on a real time automotive turbocharger test rig. After validating the response data, the model is employed to identify the bearing parameters using inverse analysis methodology. The optimization based identification scheme of bearing dynamic stiffness and damping coefficients is presented with the measured dynamic responses as input signatures. The robustness of the approach is illustrated with noisy input signals. Later-on, the coupled field fluid dynamic study is conducted for fully-floating ring bearing rotor system with consideration of fluid film properties and structural data of the ring, casing and journal. The pressure and temperature distributions in the floating ring bearing are obtained with appropriate boundary conditions. Further, the effect of the speed ratio on the pressure and temperature distribution is evaluated. The integrated thermo-hydrodynamic (THD) analysis of rotor- bearing system with temperature dependent oil viscosity in floating ring bearings is presented. Furthermore, the stability issues are discussed under accelerating/decelerating conditions. Effects of various parameters including unbalance and phase angle difference at the discs on the dynamics of the overall system are also studied. The influence of nonlinear external gas forces on the dynamics of the rotor is studied. Exhaust gas excitations are modelled with Muszynska’s force model along with axial engine order harmonic excitations. In turbochargers, in order to provide a stable connection between static and rotating parts, often one axial or thrust bearing is provided on compressor side in addition to two radial bearings. Effect of the thrust bearing forces on the stability of the rotor system is studied with a linear spring element model as well as by using a finite difference scheme. In order to minimize the vibration amplitudes at critical and sub-critical operations, semiactive and active control approaches are implemented. In semi-active control scheme, electrorheological fluid lubricants are used in the floating ring bearings and their effectiveness is studied under different input voltage conditions. For, the rotor supported on the foil bearings, a vibration attenuation methodology is proposed to generate a momentary preload by reducing the angular clearances which alters the film thickness via a wedge mechanism. In active control approach, conventional electromagnetic actuator with PD feedback configuration is used to provide the control forces in vibration reduction. In overall, the dynamic modeling and control studies via computer simulations saved the time with reliable results resulting in the better rotor designs
Impact of Work-life Balance on Employee Retention: The Mediation and Moderation Effect of Employee Commitment, Psychological Empowerment and Organizational Citizenship Behaviour
Get PDFIT and ITES industry has revolutionized the world and facilitated the transformation with undreamt rapidity in the global scenario. India acts as a global leader for spectacular growth in the field of information technology, which has attained USD 126 billion as revenue for both domestic and exports in the financial year 2017-18 and estimated to reach annual revenue of US $350 billion by the financial year 2025. The industry is growing at a fast speed with its increasing opportunities, services, and amplified GDP. In the contemplation with meeting the demands of the exceptional growth, industries are achieving excellence preference on survival and sustainability with the major lifeline of technology, people and process. Work-life balance measures need to be enforced to persuade and motivate the software professionals to evade organizational pressure and challenges.
Numerous researches have focussed on employee retention, which is inclined through various organizational initiatives and benefits of software organizations. However, the earlier research highlighting on WLB measures to motivate and retain the potential workforce are scant in India. Consequently, the study explored the impact of work dimensions and family dimensions of work-life balance towards enhancing perceptions on employee retention in Indian IT-ITES industry. Moreover, the research emphasizes on gauging the perceptions of employees of Indian IT-ITES industries on work-life balance, employee commitment, psychological empowerment, organizational citizenship behaviour and retention of professionals to formulate a coherent and logical connection among these study variables.
An opinion survey was fabricated among the professionals of Indian IT-ITES industry located in east, west, north and south geographic region of India. The survey has been conducted in various IT and ITES Industries like Infosys Ltd., Tata Consultancy Services Ltd., Tata Technology Ltd., Mind Tree Technology Ltd., and Wipro Ltd. located in major cities of India such as Pune, Bangalore, Bhubaneswar, Hyderabad and Jamshedpur to collect pertinent information to carry out the proposed research. The present study focuses on these five industries as all are specified in the context of both IT and ITES. A structured questionnaire encompasses of one hundred twenty one items were administered among eight hundred forty seven participants by adopting simple and stratified random sampling. In the process of opinion survey, six hundred sixty five positive and valuable responses were used owing at seventy eight percentages of response rate. The response of the participants was analyzed through SPSS 20 and AMOS 20. The preliminary analysis of data was conducted by using the descriptive statistics, correlation and regression analysis. Subsequently, the hypothesized research model was validated by using statistical tools such as exploratory factor analysis and structural equation modelling.
The outcome of the study exhibits that work and family dimensions have an imperative connection with work-life balance. Likewise, the study has found that work-life balance has a positive and significant association with employee commitment, psychological empowerment, and retention of professional. Further, employee retention has significant connections with employee commitment and psychological empowerment. Along with these employee commitment and psychological empowerment acts as a partial mediator the relationship between work-life balance and retention of professionals. Additionally, organizational citizenship behaviour is moderating the positive relationship between work- life balance and psychological empowerment, work- life balance and employee commitment where the relationship has found better when OCB is stronger.
Therefore, the study provides a comprehensive approach which may act as a blueprint for IT-ITES industries to improve and enhance perceived WLB as well as employee retention. Moreover, the research might offer substantial evidence to the HR and software managers for better perceived WLB measures and retain competent workforce through suitable mechanism and policies in the workplace along with the enrichment of professional competencies and motivation towards organizational performance
Robust Wide-Area Damping Controllers for compensating Inter-Area Oscillations in Power System
Get PDFInter-area low-frequency oscillation is one of the major problems in an interconnected power system. The low frequency oscillations are observed to when a group of generators or a single generator on one side of the tie line oscillate against a group of generators or a single generator on the other side of the tie line. The power transfer capability through tie lies is reduced due to inter-area poorly damped oscillation. Sometimes these inter area oscillations may pose a serious threat to power system stability. Local signal based conventional power system stabilizer(PSS) is used to stabilize the low-frequency oscillation. However, due to the low observability of the local controller, these are not sufficient to provide adequate damping to the inter-area oscillation. A wide-area damping controller is efficient to provide adequate
damping to inter-area oscillation. Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations. Wide Area Measurement System(WAMS) is convenient to transmit the wide area signals by using a communication channel to a remote location. The operating condition of the power system changes very often hence a wide-area damping controller(WADC) should be designed such that perform in all operating condition. The focus of this research is to design centralized robust wide area damping controller for inter-area oscillations in power system. Proportional-Integral(PI) controller is one of the most popular controllers due to its simple structure to implement. Hence, a loop shaping based PI controller is designed to improve the damping of the inter-mode of oscillations. The gains of the PI controller are optimally determined by solving a convex optimization problem by employing the primal-dual interior point method. Although the wide-area signal can be used to obtain accurate dynamic behavior of power system, but time delay appears in the wide-area signal through transmission from a remote area to a controller site. Thus, there lies a great deal of challenge to design a suitable damping controller. A Unified Smith Predictor (USP) based loop shaping H¥ controller is then designed to compensate for the time delay effect by using wide-area signal. To achieve robust stabilization, the normalized coprime factor problem is converted into a generalized H¥ optimization problem satisfying additional pole placement constraints. Communication failure of the wide-area signal is another disastrous phenomenon that occurs in a communication channel. Hence, a Dual Input Single Output (DISO) H¥ controller is proposed to achieve the control resiliency by employing two highest observability ranking wide-area signals with respect to the critical damping inter-area mode. The proposed controller provides sufficient damping to the power system ensuring its stability even when one of the wide-area signal is lost. The involvement of time-delay in the wide-area signal transmission may deteriorate the controller performance. Hence, USP approach is adopted to design the H¥ controller with additional pole placement constraints to compensate a range of communication delay. Although the higher-order controller exhibits good damping performance, but its design remains always a challenge while implement is in the large power system. A speed-based fixed low-order Wide-Area Damping Controller (WADC) is proposed by using the non-convex and non-smooth optimization technique. The controller is synthesized by minimizing the objective function defined on the basis of the spectral abscissa, complex
stability radius, and H¥ norm minimization. The time delay effect is considered in the synchronized and non-synchronized feedback loop. The fixed low-order synchronized and non-synchronized WADC is proposed considering the delay in synchronized as well as in the non-synchronized feedback signals. The performances and effectiveness of all the above designed controllers namely loop shaping PI controller, USP based loop shaping H¥ controller, USP based DISO H¥ controller and fixed order H¥ controller have been verified by considering two case studies namely the Kundurs two-area system and IEEE-39 bus system considering different operating points. It is observed from small-signal analysis and time-domain simulation in MATLAB/Simulink that the proposed wide-area damping controllers provide adequate damping to inter-area oscillations and compensate for the adverse effect of the time delay. In addition, it is also observed that the proposed fixed low-order (2nd) wide-area damping controller provides slightly better damping performance than a higher order controller
Development of Spray-dried Probiotic Powder from Ultrasound-assisted Enzymatically Extracted Sohiong (Prunus nepalensis) Juice
No full textConsumer interest in non-dairy based functional foods has significantly increased due to lactose intolerance, casein allergy, and associated cholesterol risks with dairy products. Fruit-based products could be an excellent alternative option. Sohiong (Prunus nepalensis) fruit is widely available in the north-eastern part of India and is nutritious. However, due to lack of proper value addition techniques, the fruit remains underutilized. There is a need to develop a process to utilize Sohiong fruit. For the present work, Sohiong fruit was explored to develop a process for a possible fruit-based probiotic product. Various physical attributes and their relationships with mass (all, small, medium, and large groups) were modeled using linear, quadratic, S-curve, and power models. Textural and biochemical properties of Sohiong fruit were also determined. The results of physicochemical characterization and mass modeling of the fruit would add information to the scientific knowledge base. It would help in the design and development of storage, handling, processing and value-addition protocols and equipment for better utilization of the fruit. The Sohiong juice was extracted using ultrasound and pectinase enzyme. The process variables in juice extraction were modeled and optimized by Box-Behnken design. The ultrasound pretreatment increased the juice yield by 20% and reduced the juice extraction time significantly compared to enzyme treatment alone. The juice recovery and the quality of juice were found to be optimum at 90% ultrasound amplitude with an ultrasound treatment time of 9.95 minutes, enzyme concentration of 0.03% w/w, and incubation time of 57.44 minutes. The extracted juice was then fermented with probiotic Lactobacillus plantarum ssp. plantarum MCC 2974. The fermented juice was analyzed for physical and phytochemical properties. During fermentation, the number of viable probiotic cells increased up to 10 Log CFU/ml. The juice was then spray dried with additives for encapsulation, and the process was optimized to make probiotic Sohiong powder. The spray-dried powder yield was 57.68% (w/w) with a moisture content of 3.95% (w.b.). The encapsulation efficiency was 85.75%, with a probiotic cell count of 7.00 Log CFU/g. The cost of producing probiotic Sohiong powder was ₹10.54 INR per gram. The powder was characterized for various quality parameters such as particle morphology (FESEM), rehydration time, hygroscopicity, density, crystallinity (XRD), glass transition temperature, and probiotic viability. The storage stability of the powder was determined through moisture sorption isotherm modeling. Peleg model fitted best with highest R2adj. and lowest RMSE. The effects of storage time on probiotic viability, physicochemical, and sensory properties of the Sohiong powder were investigated and were found to be acceptable for consumption. The powder could be stored up to 36 days at 25oC and 50% RH with an acceptable probiotic cell count of 6.12 Log CFU/g. With proper packaging and storage conditions, the probiotic Sohiong powder could be stored for an extended period. The results are promising and suggest the feasibility of producing non-dairy based probiotic Sohiong powder at an industrial scale
Novel Graphene Oxide Based Nanocomposites: Synthesis and Application Towards Adsorptive Removal of Toxic Inorganic/Organic Pollutants from Aqueous Media
Get PDFIn this doctoral work, we have synthesized a series of GO based composite nanoadsorbents such as MgO-MgFe2O4 decorated GO (MgO-MgFe2O4/GO), amine functionalized GO mounted with ZnO-ZnFe2O4 (NH2-GO/ZnO-ZnFe2O4), AlOOH-FeOOH nanorods functionalized GO (GO/AlOOH-FeOOH) and GO/g-C3N4 decorated with Fe3O4 (GO/g-C3N4-Fe3O4) nanomaterials by using hydrothermal method. Then the prepared GO based metal oxide nanocomposites were used as novel adsorbent for adsorption study of inorganic pollutants such as fluoride ions (F-), hexavalent chromium (Cr(VI)), arsenate (As(V)) and organic pollutants like methylene blue (MB) dye, tetracycline (TC) antibiotic from water. The formation, composition, bonding, crystalline phase, surface morphology, size, and surface area of these prepared nanocomposites were analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, and BET analytical techniques. Batch adsorption experiments were carried out under various conditions including pH, time, concentration, adsorbent dose and temperature.
The synthesized MgO-MgFe2O4/GO magnetic nanocomposite was used as adsorbent for removal of F- ions from water. The maximum adsorption capacity for F- ions removal is found to be 34 mg/g, which is higher as comparable to MgO-Fe2O3 nanocomposite. The amine functionalized GO decorated with ZnO-ZnFe2O4 (NH2-GO/ZnO-ZnFe2O4) nanocomposite material was used for remediation of Cr (VI) from water. It was observed that introduction of NH2 groups to GO/ZnO-ZnFe2O4 nanocomposite play a very important role for remediation of hexavalent chromium with a maximum uptake capacity of 109.89 mg/g. Apart from this we have also prepared GO/AlOOH-FeOOH composite nanomaterials by one step hydrothermal method and have used for decontamination of arsenate (As(V)) ions from water. Experimental finding reveals that the prepared GO based nanocomposite material is highly efficient for remediation of As(V) ions from water. Furthermore, we have also synthesized GO/g-C3N4 (graphitic carbon nitride) 2D layered composite materials decorated with Fe3O4 nanoparticles and have used for removal of methylene blue (MB) dye and tetracycline (TC) antibiotic from aqueous media. It was found that the adsorption of TC and MB was pH dependent and maximum adsorption capacities of 120 and 220 mg/g were achieved for TC and MB respectively. All the prepared GO based nanoadsorbents were regenerated and reused up to 5 successive cycles without major loss in their sorption capacity. From the obtained experimental results, plausible adsorption mechanism has been proposed for all adsorption process