7940 research outputs found
Sort by
Studies on a Dual Fuel Engine with a Waste Heat Recovery Unit
No full textNowadays, electrical generators are used as stand by power generators in large buildings such as educational institutions, hospitals, auditorium, etc., for providing electrical power during electrical power shutdown or failures. Owing to higher thermal efficiency and durability, compression ignition (CI) engines are mainly used in standby electrical generators. Although, diesel is mainly used as a fuel to operate such generators, utilization of different alternate fuels to reduce dependency of diesel and also reduce engine exhaust emissions is of great interest today. The main objective of dual fuel technology is to promote homogeneity of combustible charge, which leads to enhance the thermal efficiency. This research study basically follows three steps viz., production of biofuel, engine experimentation and waste heat recovery analysis. For the research work, Waste cooking oil (WCO) and spent tea waste (STW) which were disposed in the hostel premises and institute canteens at NIT Rourkela were considered as the feedstock for production of biofuel. odiesel was obtained from WCO using a two-stage esterification process. The produced waste cooking oil methyl ester (WCOME) was characterized, and the physico-chemical properties were also determined for its use as a pilot fuel in CI engine. Since the amount of STW disposed was not very high, an initial assessment was carried out to check the potential of biogas production by co-digesting STW with cow manure. The use of STW offered two advantages when co-digestion was done; (i) reduced the amount of cow manure used and (ii) reduces the anthropogenic activity. The cow manure and STW were mixed at different proportions viz 50:50, 60:40, 70:30, 80:20 and 100:0 and kept in AD1, AD2, AD3, AD4 and AD5 digesters respectively. The experiments were carried out different input parameters such as pH, carbon to nitrogen (C/N) ratio, and digestion time. From the experimental results, the highest biogas yield was obtained for AD3 which was found to be about 86.4 ml. It was also revealed that, the AD3 digester contained higher methane content of about 71% followed by AD4 (68%). Further, the experimental results obtained from the laboratory scale were predicted through a novel fuzzy regression approach.
A single cylinder four stroke, air cooled, DI diesel engine was modified to operate in dual fuel mode, where biogas serves as an inducted fuel, and diesel or biodiesel (WCOME) as a Abstract
ii pilot fuel. During the initial stages of engine experiments, biogas at a flow rate of 0.25 to 1.0 kg/h at a regular interval of 0.25 kg/h was allowed during suction stroke; whereas diesel used as a pilot fuel. The combustion, performance and emission analyses of the dual fuel engine were analyzed and compared with those of the diesel operation and recorded as baseline data. The test results indicated that, BDDFM0.75 exhibited higher cylinder peak pressure and maximum rate of pressure rise of about 58.72 bar and 3.59 bar/°CA respectively at full load. Simultaneous reduction of NO and smoke emissions of 17.2% and 4.2% respectively were observed in BDDFM0.75 operation when compared to those of diesel at full load. It was ascertained that, biogas at a flow rate of 0.75 kg/h was found to be optimum. By using the optimum biogas flow rate of 0.75 kg/h, further the experiments were carried out to increase the thermal efficiency of the test dual fuel engine by considering three parameters at three levels; advancing the pilot injection to 3°CA in the interval of 1.5°CA along with standard (23°CA), increasing the injection pressure to 240 bar with the interval of 20 bar along with standard (200 bar), and compression ratio was modified to 16.5, 17.5 and 18.5. Hence, a total of 27 sets of experiments were performed to choose the optimum condition. It was observed that, at 240 bar, 24.5°CA with a CR18.5, the dual fuel operated engine reached a maximum BTE of about 31.2% which was higher by about 4.5% than that of diesel at full load. It was also noticed that, at the optimum conditions of the engine, i.e., at 240 bar, 24.5°CA with a CR18.5, about 2.43 kW was wasted into the atmosphere through the exhaust gases, which accounted for 16.1% of the total energy supplied by the fuel (WCOME+biogas). Hence, further investigation was carried out to convert the waste heat into useful electrical energy using thermos-electric generation (TEG).
Therefore, as a third step, a mathematical model was developed to assess the performance parameters of TEG. Then, the experiments were carried out in the same test dual fuel engine at optimum engine parameters (240 bar, 24.5°CA and CR18.5 with 0.75 kg/h of biogas) using a TEG module fitted to the engine exhaust. The conversion efficiency of the TEG was measured in terms of voltage, current, temperature difference (ΔT) and power generated at different engine loading conditions. From the test results, it was found that, a maximum of 4.2 W power was generated at 75% load of the engine for 10 modules. The conversion efficiency of the TEG was found to be about 2.1% at 75% load. Theoretically, a maximum cold side temperature of the module (Tc) was found to be about 218°C, which was only 2.75% deviated from the experimental results. From the obtained results, it was understood that, ΔT played a significant role in improving the performance of a TEG system. The salient Abstract iii features of heat pipes such as no moving parts, passive energy recovery, and silent in operation could serve as a heat sink for a medium temperature range (300°C). Therefore, an attempt was made to increase the temperature difference (ΔT) across the modules by integrating or placing the heat pipe on the cold side of thermos-electric module. Experiments were conducted at two different conditions (i) with heat pipe and (ii) without heat pipe at different engine loading conditions. The results revealed that, a significant improvement in the ΔT was noticed when heat pipe was used as the heat sink. A maximum ΔT of about 65°C for n=1, which was higher by about 680% than that without the heat pipe at 75% engine load. A maximum power of about 6.1 W was generated by the TEG-heat pipe with conversion efficiency of about 2.9% at 75% engine load. The results of the research encourage implementing the idea in a diesel generator of different capacities available in the Institute campus
Ocular Feature Detection Under Spectacles
No full textOcular image processing is a primary step in many applications such as iris recognition, driver fatigue detection, gaze tracking etc. Occlusion, glare, and secondary reflections formed due to and on the spectacles—results in poor detection and localization of eye features. In this thesis, the challenges that arise from the usage of spectacles are termed as “The spectacle problem”. In literature most of the existing algorithms are targeted to remove occlusion due to spectacle frame and have not considered the influence of specularities. To alleviate the issues of specularities and to improve ocular feature detection under spectacles two new approaches viz. (i) Low rank model-based approach (multiple image-based approach), (ii) Dichromatic model-based approach (single image-based approach)—are proposed. In the proposed Low rank model-based approach, glare/reflection removal is formulated as a classification problem and Low-rank decomposition technique is employed to overcome these challenges. Experimental analysis on the proposed approach revealed that due to the inability to capture eye dynamics—this proposed approach suits for detection and localization of coarser eye features only. So, by employing the Dichromatic reflection model (DRM) and extending it to Hue-Saturation-Value colour space, a single image-based approach is proposed to overcome the limitations of multiple image-based approaches. By solving the least-squares problem of the DRM, reflection separation is implemented on a single-pixel level to decompose a given image into diffuse (spectacle problem free) and specular components. Human alertness-level detection from eye blinks (under spectacles) is considered as a case study to validate the proposed algorithm. Literature review on the available databases lead to an observation that a complete database which enlists the challenges of spectacle problem along with the benchmark data is unavailable. Therefore, an experiment is designed to yield a video database of 58 human subjects wearing spectacles and are at different levels of alertness. Experiments on this database demonstrate that the proposed Dichromatic model-based approach achieves desirable spectacle problem removal results within minimum execution time compared to the state-of-the-art. Additionally, an alertness-level index that aids in the cross-verification of any visual cue based alertness level detection approach is proposed
RFID Antennas for Biomedical Applications
No full textIn this current technological trend, radio frequency identification (RFID) can provide the solution for modern wireless data transmission and reception for a broad range of identification, tracking, and surveillance applications. The RFID technology can be a potential competitor to the optical barcode technology by introducing the chipless RFID tags. The fully printable chipless RFID technology can reduce the manufacturing cost to a great extent and might be useful in a vast range of applications. This dissertation is aimed at building design methodology, analysis, and ideas regarding RFID antennas required for biomedical applications. It focuses on the limitations associated with the technology and the design challenges. It also aims to overcome the above-discussed drawbacks as well as enhancing overall microwave system performance by proposing new structures. In this research work, the design of chipless RFID reader and tag antennas are investigated for biomedical applications. Both linearly polarized (LP) and circularly polarized (CP) reader antennas are investigated with mathematical modeling and analysis. The radiation characteristics are evaluated along with the full-wave analysis and physical measurement. The first LP antenna design presented in this thesis can be used as an RFID reader having a wide bandwidth of 64.86% for vital sign monitoring applications. The planar monopole antenna comprises of a primary radiating element having one half of a Koch snowflake fractal geometry, and a partial ground plane. The analytical model provides a comprehensive understanding of the antenna operation. Measurement of the fabricated prototype confirms that the design possesses an operational bandwidth from 47.84 GHz with a peak realized gain of 3.4 dBi at 7.2 GHz with omnidirectional radiation characteristics. The proposed antenna has a dimension of 0.33__0.49__0.03_, at 5.8 GHz and is found compact compared to some recently reported designs. Similarly, a Pythagorean-tree fractal monopole RFID reader antenna is analyzed for sleep apnoea applications. The antenna is fed by the coplanar waveguide (CPW) feeding method with the filleted ground plane. The lumped element circuit of proposed design is validated with full-wave simulation model to understand the operation of the structure. The measurement results show a wide bandwidth in the frequency range of 4.227.52 GHz and a peak realized gain of 2.9 dBi at 5.8 GHz. The use of fractal geometry is mainly to reduce the metallic footprint size, along with to obtain a wider bandwidth. The LP antenna is having an overall dimension of 0.36__0.43__0.015_ at 5.8 GHz covering the industrial scientific and medical (ISM) band. In this thesis, a planar monopole antenna having a slotted ground plane is also presented. The antenna is energized by a 50-Ω feedline having a sigma-shaped radiator. The proposed design resonates at 5.8 GHz with an operational bandwidth from 5.715.9 GHz. The radiation characteristics of the structure show the realized gain value greater than 3.6 dBi in the entire operating frequency range. The antenna has an overall dimension of 0.55__0.55__0.03_ at 5.8 GHz and can be a suitable RFID reader in the ISM band. In another LP antenna design, the analysis of a meandered line monopole antenna with a defected ground structure (DGS) for RFID applications is investigated. In the proposed antenna, the linearly polarized meandered line acts as the main radiator whereas the inverted C-shaped patch acts as a parasitic element. The defects on the ground plane are responsible for providing low pass filter performance. From the measurement, it is found that the antenna operates over the 5.74–6 GHz with a resonance at 5.82 GHz. The designed antenna structure shows omnidirectional radiation characteristics with the realized gain value greater than 4 dBi in the entire operating frequency range. It has an overall dimension of 0.55_ _ 0.55_ _ 0.03_ at resonating frequency which is effectively fit for use in RFID readers operating at 5.82 GHz ISM band. In this thesis, a single-feed, miniaturized, CP microstrip patch antenna (MPA) using Koch fractal geometry for RFID applications is presented. The design consists of a probe-fed slotted square-shaped patch with the fractal edge and two pairs of capacitively coupled
grounded metal strips. The proposed design methodology is validated by designing two prototypes (Antenna 1 and Antenna 2), which are operating at 2.435 GHz and 5.78 GHz respectively. Both antennas show right-hand circular polarization (RHCP) characteristics with 3 dB axial ratio bandwidth (ARBW) covering 2.433–2.439 GHz and 5.75–5.8 GHz respectively. This design offers a compact antenna to meet the demands of portable wireless devices. The thesis also describes the design, modeling, and analysis of a two-bit retransmission-based chipless RFID tag operating in the microwave ISM band. The chipless RFID tag has cross-polarized transmitting and receiving antennas along with open-stub resonators. The fabricated prototype confirms 2-bit data encoding in which the simulation results are strongly related to the experimental outcomes. The proposed tag occupy an overall size of 0:53__0:53__0:012_ (at f = 2:4 GHz) and can be suitable for biomedical applications. At the end of this research work, the broad idea of a chipless RFID system is provided in the Appendix section. It includes the overview of a complete reader system to read the encoded data from a chipless RFID tag. This investigates each of the elements of the reader system and the functionality. In this current technological trend, radio frequency identification (RFID) can provide the solution for modern wireless data transmission and reception for a broad range of identification, tracking, and surveillance applications. The RFID technology can be a potential competitor to the optical barcode technology by introducing the chipless RFID tags. The fully printable chipless RFID technology can reduce the manufacturing cost to a great extent and might be useful in a vast range of applications. This dissertation is aimed at building design methodology, analysis, and ideas regarding RFID antennas required for biomedical applications. It focuses on the limitations associated with the technology and the design challenges. It also aims to overcome the above-discussed drawbacks as well as enhancing overall microwave system performance by proposing new structures. In this research work, the design of chipless RFID reader and tag antennas are investigated for biomedical applications. Both linearly polarized (LP) and circularly polarized (CP) reader antennas are investigated with mathematical modeling and analysis. The radiation characteristics are evaluated along with the full-wave analysis and physical measurement. The first LP antenna design presented in this thesis can be used as an RFID reader having a wide bandwidth of 64.86% for vital sign monitoring applications. The planar monopole antenna comprises of a primary radiating element having one half of a Koch snowflake fractal geometry, and a partial ground plane. The analytical model provides a comprehensive understanding of the antenna operation. Measurement of the fabricated prototype confirms that the design possesses an operational bandwidth from 47.84 GHz with a peak realized gain of 3.4 dBi at 7.2 GHz with omnidirectional radiation characteristics. The proposed antenna has a dimension of 0.33__0.49__0.03_, at 5.8 GHz and is found compact compared to some recently reported designs. Similarly, a Pythagorean-tree fractal monopole RFID reader antenna is analyzed for sleep apnoea applications. The antenna is fed by the coplanar waveguide (CPW) feeding method with the filleted ground plane. The lumped element circuit of proposed design is validated with full-wave simulation model to understand the operation of the structure. The measurement results show a wide bandwidth in the frequency range of 4.227.52 GHz and a peak realized gain of 2.9 dBi at 5.8 GHz. The use of fractal geometry is mainly to reduce the metallic footprint size, along with to obtain a wider bandwidth. The LP antenna is having an overall dimension of 0.36__0.43__0.015_ at 5.8 GHz covering the industrial scientific and medical (ISM) band. In this thesis, a planar monopole antenna having a slotted ground plane is also presented. The antenna is energized by a 50-Ω feedline having a sigma-shaped radiator. The proposed design resonates at 5.8 GHz with an operational bandwidth from 5.715.9 GHz. The radiation characteristics of the structure show the realized gain value greater than 3.6 dBi in the entire operating frequency range. The antenna has an overall dimension of 0.55__0.55__0.03_ at 5.8 GHz and can be a suitable RFID reader in the ISM band. In another LP antenna design, the analysis of a meandered line monopole antenna with a defected ground structure (DGS) for RFID applications is investigated. In the proposed antenna, the linearly polarized meandered line acts as the main radiator whereas the inverted C-shaped patch acts as a parasitic element. The defects on the ground plane are responsible for providing low pass filter performance. From the measurement, it is found that the antenna operates over the 5.74–6 GHz with a resonance at 5.82 GHz. The designed antenna structure shows omnidirectional radiation characteristics with the realized gain value greater than 4 dBi in the entire operating frequency range. It has an overall dimension of 0.55_ _ 0.55_ _ 0.03_ at resonating frequency which is effectively fit for use in RFID readers operating at 5.82 GHz ISM band. In this thesis, a single-feed, miniaturized, CP microstrip patch antenna (MPA) using Koch fractal geometry for RFID applications is presented. The design consists of a probe-fed slotted square-shaped patch with the fractal edge and two pairs of capacitively coupled grounded metal strips. The proposed design methodology is validated by designing two prototypes (Antenna 1 and Antenna 2), which are operating at 2.435 GHz and 5.78 GHz respectively. Both antennas show right-hand circular polarization (RHCP) characteristics with 3 dB axial ratio bandwidth (ARBW) covering 2.433–2.439 GHz and 5.75–5.8 GHz respectively. This design offers a compact antenna to meet the demands of portable wireless devices. The thesis also describes the design, modeling, and analysis of a two-bit retransmission-based chipless RFID tag operating in the microwave ISM band. The chipless RFID tag has cross-polarized transmitting and receiving antennas along with open-stub resonators. The fabricated prototype confirms 2-bit data encoding in which the simulation results are strongly related to the experimental outcomes. The proposed tag occupy an overall size of 0:53__0:53__0:012_ (at f = 2:4 GHz) and can be suitable for biomedical applications. At the end of this research work, the broad idea of a chipless RFID system is provided in the Appendix section. It includes the overview of a complete reader system to read the encoded data from a chipless RFID tag. This investigates each of the elements of the reader system and the functionality
Biodegradation Study of Some Commonly Used Plasticizers (Phthalate Esters) and Development of a Vegetable Oil-Based Plasticizer
No full textIn the present study, an attempt was made to lessen the environmental pollution burden of commonly used plasticizers, phthalate esters (PEs). The largely consumed low molecular weight PEs, dimethyl phthalate (DMP) and diethyl phthalate (DEP), were of primary focus to explore their biodegradation. Two aerobic bacterium strains tolerating high concentrations of PEs were isolated from soil contaminated with municipal wastewater. Based on the morphological, biochemical characteristics, and 16S rRNA sequencing, the isolates were identified as Bacillus sp. KS1 and Micrococcus sp. KS2. To enhance the biodegradation efficiency of isolates, process parameter optimization was performed by applying Plackett-Burman design and response surface methodology (RSM) based central composite design (CCD). Batch biodegradation experiments were performed in shake flask at optimum levels of process parameters. Bacillus sp. KS1 showed tolerance up to 1700 ± 12.5 mg/l of DMP and 1650 ± 17.8 mg/l of DEP while Micrococcus sp. KS2 exhibited tolerance up to 1500 ± 23.5 mg/l of DMP and DEP. The growth kinetic study of the high concentrations of PEs was performed by using growth kinetic models where the Haldane model was found to fit well with the experimental data suggesting the substrate inhibition effect. Analysis of PEs degradation residuals by Gas chromatography-Mass spectrometry (GC-MS) revealed the presence of monomethyl phthalate (MMP), monoethyl phthalate (MEP) and phthalic acid (PA) as the PEs degradation metabolites. To treat PEs containing synthetic wastewater, an internal loop airlift bioreactor (ILABR) was fabricated with an overall tank capacity of 4.7 liters and a working volume of 3.8 liters. For low viscous Newtonian liquids, viscosity showed a substantial positive effect on the gas holdup, liquid velocity, and mass transfer. Batch experiments of DMP and DEP degradation were carried out by mixed culture and combined system comprising suspended biomass and biofilm of pure cultures of isolates in an ILABR set up independently. The mixed culture showed tolerance up to 2250 ± 32.4 mg/l of PEs while the combined system exhibited enhanced efficiency of PEs degradation, as the tolerance capability was increased up to 2500 ± 28.9 mg/l of PEs. Thus, the study established the potential of microbes for treating PEs containing wastewater. The present study was also focused on the development of a vegetable oil based substitute for PEs. Citrullus lanatus (watermelon) seed oil (CLO) was considered for this objective since it is still unexplored in the perspective of epoxidation and its application as a plasticizer. CLO was epoxidized in the presence of acetic acid, sulphuric acid, and hydrogen peroxide. Epoxidized Citrullus lanatus seed oil (ECLO) with the maximum conversion of iodine value of 86.7% and relative conversion to oxirane oxygen of 84.2% was attained. FTIR, 1H NMR, and 13C NMR analysis confirmed the maximum conversion of the double bond to the oxirane group of an epoxide. Further, soft polyvinyl chloride (PVC) films plasticized with ECLO showed better surface morphology and improved mechanical properties. The plasticization effect was observed based on exudation, migration stability, thermal stability, and reduction in glass transition temperature (Tg). The comparison study of ECLO and dioctyl phthalate (DOP) as a plasticizer for soft PVC films established the effectivity of ECLO and confirmed its exploitation as a partial substitute for DOP. The biodegradable polymer is a current insistence to counter the hurdle of plastic materials disposal. In the present study, the biodeterioration of soft polyvinyl chloride (PVC) films plasticized with ECLO was explored in vitro by isolated strains, Bacillus sp. KS1 and Micrococcus sp. KS2 independently. Post 90 days of inoculation with bacterial isolates, morphological, and structural alterations of PVC films were observed. The changes in thermal stability, weight loss, and molecular modifications of PVC films exhibited evident microbial utilization of ECLO. However, the plasticized PVC films without inoculating by isolates displayed no significant deterioration. The obtained results confirmed that the isolates could effectively deteriorate PVC films by utilizing a developed plasticizer (ECLO) as a source of energy from the polymer matrix. Thus, the present research work delivered a potential plasticizer (ECLO) as an alternative for toxic PEs
Molecular Design, Synthesis and Biological Evaluation of Novel Transition Metal Complexes Featuring ON, ONO & ONS Donor Ligands
No full textDevelopment of novel transition metal based compounds for their potential applications as therapeutic or diagnostic agents is an integral part of medicinal chemistry. Transition metal complexes have been widely used as chemotherapeutic agents in the treatment of several types of malignancies, such as colon, lung and breast cancers. Moreover, they can exist in a variety of oxidation states and this characteristic enable them to accommodate a variety of organic molecules or ligands around them. Designing of new ligands through judicious substitution and tuning of metal-binding sites offers the opportunity in the modification and advancement of such agents, thus making metal based drugs promising pharmacological candidates. A number of reports of metal complexes encourage further studies for exploration of new metallodrugs with attractive properties like biological potency, easy accessibility, least toxicity and improved physical profile. Bearing these factors in mind, in this dissertation the chemistry of a series of transition metal (V, Ni, Mo, Cu, Ru, & Zn) complexes of tri- and tetradentate ONO, ONS and ONNO donating azohydrazones, aroylhydrazone, thiosemicarbazones and salan ligands are reported, with special reference to their pharmacological activity and solution property. All the synthesized ligands and their corresponding metal complexes have been successfully characterized by several physicochemical (elemental analysis), spectroscopic (UV-Vis, IR and NMR), spectrometric (ESI-MS) and electrochemical (cyclic voltammetry) methods. The structures of the complexes were further confirmed by single crystal X-ray diffraction analysis. The solution behavior of few complexes has also been studied in order to understand their transformation, interconversion, changes in coordination geometry, and nuclearity taking place in solution phase. Therein, the complexes were studied for their biological activity through interaction with DNA (Calf Thymus DNA, G-quadruplex DNA and Supercoiled pUC19 DNA) and proteins (Human Serum Albumin) through various analytical and electrophoresis techniques. The in vitro antiproliferative activity of the synthesized complexes was studied against different cancer [human cervical cancer (HeLa), human colorectal adenocarcinoma (HT-29), human breast adenocarcinoma, (MCF-7)], and noncancerous cell lines [human epidermal keratinocyte cells (HaCaT) and mouse embryonic fibroblast cell line (NIH-3T3)]. Additionally, the zinc complexes were evaluated for their phosphatase activity by using para-nitrophenyl phosphate (PNPP) and bis(2,4–dinitrophenyl)phosphate (BNPP) as substrates. The results obtained from the above studies suggested the test complexes to be excellent DNA and protein binders. In addition, the in vitro antiproliferative activity of the complexes points toward their significance as potential lead molecules for drug designing. The complexes studied herein showed similar, or in some cases even better in vitro cytotoxicity on comparison to various clinically reported chemotherapeutic drugs. Besides, the zinc complexes showed moderate phosphatase activity against model substrates. Finally, a plausible rationale for the enhanced biological activities of all the complexes like results of modifications in the ligand environment and the nature or the number of metal centers has also been discussed Apart from that, the catalytic applications (especially in oxidative bromination of thymol and styrene) of vanadium(V) complexes and magnetic susceptibility of dimeric copper(II) complexes has also been explored keeping their individual metal importance in consideration
Characterization of Welded Joints of Similar and Dissimilar Metals with Various Processing Routes
No full textIn this work, an attempt has been made to join IS 2062 mild steel plates for similar metal welding and both IS 2062 mild steel and AISI 409M stainless steel plates for dissimilar metal welding by various processing routes i.e. gas metal arc welding (GMAW) and shielded metal arc welding (SMAW) in both straight polarity and reverse polarity. The dimensions of the plate used for welding in both similar and dissimilar metal were taken as length of 100 mm and breadth of 50 mm as per ASTM standard. For similar metal welding process, the thickness was varying from 5 mm, 6 mm and 8 mm, respectively and for dissimilar metal welding only 8 mm thickness was considered. In both welding process, the input current was considered at 120 A, 140 A and 160 A, respectively. The welded samples were vigorously investigated with various zones by using of various universal testing machines. The microstructural analysis of welded samples was carried out by using optical microscope and scanning electron microscope (SEM) of various zones i.e. fusion zone, heat affected zone (HAZ) to analyze the grain sizes changing with various process parameters. Maximum grain size of 17.09 μm was observed in metal coarsening zone and minimum grain size of 5.43 μm was investigated in grain refinement zone of welded mild steel plates with the application of 160 A current on 8 mm thick plates in SMAW straight polarity welding. In the X-ray diffraction pattern the peaks of α-ferrite were observed, at 2θ values of 52.30˚, 77.17˚ and, 99.65˚, respectively of the welded samples for both GMAW and SMAW processes. All the x- ray patterns for the welds at different current and different plate thicknesses were studied. But all of them yielded the same profiles with no variations at all. From hardness study it was found that maximum hardness was observed in the grain refinement zone of each process and with an observation of increasing in hardness while increasing current. Tensile test was conducted and observed that optimum tensile strength of 387.879 MPa was found in GMAW process by the application of 160 A current on 5 mm thick material. To determine the toughness of the joint, impact test was conducted and maximum toughness of 180.728 J/cm2 was noticed with the application of 120 A current on 8 mm thick plates in GMAW process. In dissimilar metal welding, the materials were welded by variations of welding current with consideration of 8 mm thick plates with various processing routes like GMAW and SMAW (Reverse polarity). Then the microstructural and mechanical characterizations of welded specimens were examined. In microstructural study maximum coarse grains in metal coarsening zone and fine grains in grain refinement zones were observed in GMAW processes due to more efficiency of heat inputs on work piece. Fe-Ni intermetallic, Fe carbides and Fe-Cr solid solution were investigated through X-ray diffraction study in GMAW and SMAW processes for the dissimilar metal welding. Maximum hardness of 543.8 HV was observed in case of SMAW process in fusion zone with application of 160 A current. Optimum tensile strength of 365.15 MPa was investigated in case of GMAW process with application of 120 A current. From impact test study it was investigated that maximum impact toughness of 178.28 J/cm2 was observed in case of GMAW process with application of 120 A current
Mechanistic Insight on the Role of ESAT-6 in Modulating Host Defensive Pathways Through MicroRNA-30a in Mycobacteria Infected Macrophages
No full textThe weaponry possessed by Mycobacterium tuberculosis (M. tb) in the form of immunodominant antigens hijack the host defense system to give a survival advantage to this intracellular fiend, but the mechanism of this control is not entirely known. The present study was undertaken to understand the effect of mycobacterial antigens on the anti-mycobacterial effect of Calcimycin. We found significant downregulation of autophagy by purified protein derivative (PPD) 3 (PPD fraction with a molecular weight of antigens > 3 kDa) pre-treatment in Calcimycin-treated phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 (dTHP-1) cells compared to PPD 10 (antigenic mol. weight > 10 kDa). This reduction in autophagy also corroborated with the enhanced survival of M. smegmatis and M. bovis BCG in macrophages. We further demonstrate that recombinant early secreted antigenic target 6 (rESAT-6), an immunodominant antigen of M. tb, is responsible for inhibiting Calcimycin-induced autophagy and enhancing intracellular survival of mycobacteria. We also show that pre-treatment with rESAT-6 upregulates microRNA (miR)-30a-3p expression and vis-à-vis downregulates miR-30a-5p expression in Calcimycin-treated dTHP-1 cells. Further, transfection studies using miR-30a-3p inhibitor or -5p mimic highlighted the contrary roles of different arms of the same miRNA in regulating autophagy and IL-18 response by rESAT-6 in Calcimycin-treated dTHP-1 cells. By using either IL-18 neutralizing antibody or inhibitors of phosphoinositide 3-kinase (PI3K)/NF-κB/phagosome-lysosome fusion in the miRNA-30a transfected background, IL-18 mediated signaling and intracellular killing of mycobacteria was reversed in the presence of rESAT-6. Overall, the results of this study conclusively prove the contrary roles of miR-30a-3p and miR-30a-5p in regulating autophagy and IL-18-mediated phagosome-lysosome fusion by rESAT-6 in dTHP-1 cells upon Calcimycin treatment that affected intracellular survival of mycobacteria
Rapid Thermal Synthesis of Molybdenum Disulfide Thin Films for Infrared Detectors
No full textAutomation and modernization of gadgets in automobiles, safety, remote sensing, defence, agriculture, environmental pollution, imaging in nuclear medicine rely on the use of infrared (IR) detectors. In the current era of IR detectors, the quest for advanced materials turned the research towards transition metal dichalcogenides. Molybdenum disulfide (MoS2) is found to be a suitable candidate for IR detectors as it outperforms over a broad range of IR spectrum. In order to obtain a superior quality of MoS2 films, chemical vapor deposition has been explored which involves sulfurization of various Mo based compounds using inert carrier gases over a prolonged period of time at high process temperature. In this research, a short period growth of MoS2 films is implemented by face to face arrangement of pre-deposited S/Mo films on silicon substrates using rapid thermal process (RTP). In this work, an attempt has been made to explore the dependence of the RTP parameters such as growth duration, process time and gas flow rate on the morphological, microstructural and electronic properties of MoS2 thin films. Morphological properties of RTP grown MoS2 thin films have been investigated by Field Emission Scanning Electron Microscope and Atomic Force Microscope technique, whereas microstructural properties have been studied by X-Ray Diffraction and Raman technique. The electronic properties of the MoS2 films are estimated by current-voltage and capacitance-voltage technique. A correlation between the morphological and electronic properties of RTP grown MoS2 thin film has been systematically established in this research. The MoS2 films with improved morphological and electronic properties have been obtained at 800 °C for the growth duration of 5 min with the Ar:H2 flow rate of 10:1. The n-type and p-type MoS2 thin films are fabricated using benzyl viologen (BV) and gold chloride (AuCl3) solution, respectively by spin coating technique. The modulation of morphological and electronic properties of MoS2/Si samples was studied with the variation in concentration of BV and AuCl3 solution, number of spin coats and temperature of post-treatment annealing. The MoS2 based photoconductive detector, heterojunction, homojunction and Schottky junction are fabricated to investigate IR detection behavior at the wavelength of 850 nm, 940 nm and 1060 nm. MoS2 based Schottky junction has shown a higher current On/Off ratio, whereas fast rise and fall time has been observed for photoconductive devices. MoS2 thin films, synthesized by RTP have shown comparatively better IR detection behavior for 940 nm IR illumination. The above observations will pave a suitable platform for the next generation of IR detectors
Cryopreservation of Testicular Cells and Tissues by Solid Surface Vitrification
No full textCryopreservation of testicular cells and tissues may offer a potential alternative to fertility preservation in males wherein semen cryopreservation is not possible due to non availability of sperm (e.g. pre-pubertal males, non obstructive azoospermia etc.) or non-feasibility (e.g. posthumous reproduction, pre-meiotic barriers to spermatogenesis etc.). Testicular cells, such as Leydig cells, are also emerging as a new therapeutic modality for androgen replacement therapy. However, studies on cryopreservation of Leydig cells are scarce and, testicular cryopreservation protocols are sub-optimal in human as well as farm animals such as goats. This study investigated the cryopreservation of testicular cells by open [Solid Surface Vitrification (SSV) and Microdroplet (MD) method] and closed [Plastic Straw (PS) and Plastic Vial (PV)] vitrification, and applied the modified SSV for encapsulation vitrification. Mouse Leydig cell (TM3) line was initially used to avoid batch-to-batch variation, and the optimized protocol was tested for SSV of goat testicular cell suspension (TCS) and tissues. Effect of tissue size and organ culture methods for in vitro spermatogenesis were evaluated. Results showed that the SSV method was superior to MD, PS and PV methods of vitrification in terms of post-warming viability, cytoplasmic esterase enzyme activity, mitochondrial activity and cell growth (p<0.05). Vitrification induced the activity of reactive oxygen species (ROS), which could be annihilated by supplementation of 50 µM 2-mercaptoethanol (2-ME) or 100 µM glutathione (GSH) to improve the post-warming viability of the vitrified cells (p<0.05). The vitrified-warmed Leydig cells could completely regain their cell growth characteristics after 7 days of in vitro culture. The Leydig cells could also be encapsulated into alginate beads with encapsulation efficiency of 1.2 X 105 cells/ml per bead and could be vitrified successfully by SSV. However, the size of the beads significantly influenced the post-warming viability of cells (p<0.05). The optimized SSV was also applied to SSC-enriched goat TCS and testicular tissues. Results suggest that SSV could successfully cryopreserve DAZL- and PGP9.5- positive putative SSCs, which could proliferate in vitro and form cell colonies. The SSV vitrified-warmed TCS showed similar mitochondrial activity, rate of cell proliferation and population doubling time of total cells comparable to non-vitrified control. However, during in vitro culture, vitrified-warmed cells showed significantly lower mitochondrial activity than those of non-vitrified controls, which was associated with increased ROS activity. The optimized SSV method could also successfully vitrify goat testicular tissue. However, the post-warming viability varied with the tissue size: small size tissue (~4 mm3) resulted in better viability than medium (~9 mm3) or large (~16 mm3) sized testicular tissue. The low viability of vitrified-warmed testicular tissue was associated with increased ROS activity, tissue fracture and damage to both histo-architecture and cellular components of the testis. It was also observed that organ culture (OC) method was superior (p<0.05) to hanging drop (HD) method in terms of post-warming metabolic activity on Day 7 and Day 14 of culture, respectively. Histology and scanning electron microscopy (SEM) showed the rupture of basal membrane, surface morphology and cell loss due to vitrification. However, histology and immunohistochemistry showed the progression of in vitro spermatogenesis and formation of elongated spermatozoa in both fresh and vitrified-warmed testis tissue cultured by OC method. In conclusion, results of this study suggest that modified SSV may offer a viable method for vitrifying single cell suspension of Leydig cells, mixed population of goat TCS as well as goat testicular tissue. Future work should determine the ability of vitrified-warmed testicular cells and tissues to restore male fertility upon their transplantation in recipient testes of animal models
Martian Atmospheric Characteristics Associated with Dust Storms and Clouds Realized Through Satellite Observations and MarsWRF
Get PDFDust storms and clouds are the two major atmospheric phenomena frequently seen over Mars and have the most dynamic impact on its atmosphere. The dust can alter the temperature profile, thereby controlling the weather. Understanding the clouds will give an insight into the water cycle, and water is an essential resource for any living body. Satellite observations spanning across more than two decades are playing a pivotal role in understanding the meteorological processes associated with the dust and cloud activities over Mars. However, studies of the vertical distribution of dust and water ice and their dynamical, microphysical, and radiative interactions need more attention, which will help to understand their intrinsic variation. Another aspect is understanding and predicting the thermal behavior of the atmosphere adequately, considering the complex interplay of dust and water ice forcing. Therefore, this study has analyzed the clouds and dust lifting processes using several imaging and meteorological sensors onboard different Mars orbiters.
First, the analyses are carried out during a dust lifting sequence in early southern summer near the Lunae Planum region based on the observations from the Mars Color Camera (MCC) onboard the Mars Orbiter Mission (MOM). The Mars Daily Global Maps (MDGMs) of the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) showed that the dust storm was generated in the Acidalia-storm-track region, crossed the equator, and merged with a Hellas sequence over Noachis Terra. The same is confirmed by an increased column dust opacity derived from the observations of the Mars Climate Sounder (MCS) onboard MRO. The HATDM (High Altitude Tropical Dust Maximum) is formed but with a temporal delay of 2° LS (solar longitude) after the dust storm disappearance. The study implicates, variation of the planetary boundary layer (PBL) growth, visible heating rate, and the water ice mixing ratio during the dust storm scenario for this temporal delay in dust lifting.
The aforesaid mechanism is found to be valid for the Mars year (MY) 34 (2018) global dust storm. Dust lifting is observed to continue until LS ~207 – 208° in the MARCI images and MCS column dust opacity. However, the dust abundance in the middle atmosphere shows its peak around LS 211°. HATDM is evident after LS ~190°, i.e., a few LS after the large precursor Acidalia dust storm. Also, the diurnal tide is strongly amplified at high-altitudes away from the tropics, and the vertical extent of clouds is significantly reduced. These changes are consistent with the time scale of the evolving vertical distribution of dust observed by the MCS. Overall, these delays observed in the dust movement, clouds, and tidal distribution probably reflect a vertical mixing timescale of dust irrespective of the spatial scale of a storm.
Therefore, more detailed analyses of the vertical distribution of dust and associated atmospheric impacts is carried out for a regional and a global event over Acidalia Planitia using MCS observations and ‘Mars Weather Research and Forecasting (MarsWRF)’ model simulations. The dustiness at ~25–35 km altitude contributed significantly to the column opacity during the regional dust event (RDE), which peaks at ~40–50 km for the global one (GDE). This altitudinal difference is also visible in the inversion layer formed by the combined effect of decreasing surface temperature and the downward infrared radiation from the dust. This atmospheric warming by the dust radiative heating with the inversion layer below could be associated with the presence of heating and cooling layers centered around 30–50 and 20–35 km heights, which influence the variability of ice optical depth within them. The MarsWRF simulated downward wind, PBL height, and surface radiation flux showed lesser vertical mixing from the surface and also suggested dominating downward radiation from the suspended dust, which altogether influenced the formation of a heating/cooling layer and variability of water ice clouds. The Empirical Orthogonal Function analysis suggests that the seasonal cycle of the southern hemispheric dust storms, northern hemispheric active storm track, and the cap-edge storms possibly influenced the seasonality observed in the heating/cooling layer clouds.
In the clouds' case, the present study uses five MY MCS observations for investigating the Aphelion Cloud Belt (ACB) over the tropics. The observation suggests its appearance at altitudes ~10–40 km, within -20 – 40°N and during LS ~45 – 135°. The thick clouds within the ACB show a northward movement starting from the peak phase (LS ~76 – 105°), prominently over regions nearby Lunae Planum and Xanthe Terra. The temporal evolution of the ACB shows a decreasing cloud top over the southern hemisphere and little increase over the northern hemisphere (NH), though the vertical depth of it becomes narrower. A possible association of upper tropospheric dustiness with the ACB’s northward evolution is evident mostly at an altitude range of ~18–35 km. It is supported by the migrating semidiurnal tide (SMD) as a proxy of dust or water ice forcing and upper tropospheric dust radiative heating, which showed a northward movement of their peak amplitude with the temporal evolution of the ACB.
The investigation of tropical clouds extended to the Olympus and Arsia Mons region, which provides an exciting opportunity to explore the dynamical effects related to the orographic clouds. MCS observations suggest an appearance of thick, low altitude (at ~15–32 km) clouds during LS ~35 – 150°, which is strongly controlled by the air temperature, and an occurrence of high altitude (at ~30–50 km) haze clouds during LS ~225 – 315°, which is found to be more associated with the elevated dustiness and vertical advection of dust-laden mountain induced regional circulation, as suggested by MarsWRF simulated wind. The thick clouds followed by the haze clouds maintain the cloud water content at ~0.2 and ~0.05 pr. μm. in the 1st and 2nd half of the year. However, a higher cloud vertical depth is evident during the 2nd half of the year due to the appearance of high-altitude cloud haze. The Olympus Mons region shows a more favorable condition for the thick low-altitude clouds that are mostly influenced by the consistent and stable aphelion cloud cycle. In contrast, more prominent vertical advection over the Arsia Mons region during the perihelion season drives the noticeable occurrence of haze clouds and significant east-west directional asymmetry in the cloud abundance.
Lastly, a study of dust and water ice interrelated variation is carried out using the six years (MY 29 – 34) of MCS retrievals. The correlations between dust and water ice column opacity and profiles are found to ‘switch sign’ and ‘alter within 20–40 km altitudes’ between the low-dust and high-dust seasons. During the low-dust period, the positive correlations over the latitudes 40 – 80° S and 20° S – 40°N are mainly controlled by the water ice cycle in the south polar hood clouds and ACB besides the presence of atmospheric dust in ACB’s formation stage. During the high-dust period, at southern latitudes, significant dust lifting and the associated temperature changes are found to be the reason for the strong negative correlation. And, in tropical latitudes, the significant positive relationship at relatively high altitudes (~40 km) is seen, possibly due to the presence of thin or haze clouds. The global dust storm occurrence only modulates the correlation behavior during the high-dust period and above ~40 km altitude, indicating an enhanced vertical advection. The difference in correlation behavior between low and high-dust seasons could be explained from the variation in MarsWRF simulated PBL height. Moreover, the dust and water ice interaction pattern has a prominent seasonal and altitudinal variation, which is influenced by the water ice cycle, dust cycle, or the dustice microphysical relationshi