Narendra Singh; Davinder Kaur
Abstract
Ultrathin silicon carbide (SiC) films were grown on p type Si (100) substrate by RF magnetron sputtering at constant substrate temperature of 7000C for investigating thickness dependence of structural and photoluminescence properties. The structural and Photoluminescence properties were measured by X-ray ...
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Ultrathin silicon carbide (SiC) films were grown on p type Si (100) substrate by RF magnetron sputtering at constant substrate temperature of 7000C for investigating thickness dependence of structural and photoluminescence properties. The structural and Photoluminescence properties were measured by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and photospectrometer respectively. X-ray diffraction pattern revealed (102) and dominant (105) reflections which corresponds to 4H-SiC and an enhancement in (105) peak intensity with increasing thickness was also observed. The thickness measured by X-ray reflectometry (XRR) reduces from ~ 46 nm to 12 nm by decreasing deposition time (40-10 minute) which in turn reduces the crystallite size. Photoluminescence spectra show a broad peak extending from ultraviolet to blue region centered at ~ 385 nm for film of thickness ~ 46 nm (deposition time 40 min). A shifting in Photoluminescence peak towards shorter wavelength (blue shift) with decreasing SiC ultrathin film thickness was observed, which could be attributed to quantum confinement effect. The improved Photoluminescence in ultrathin nanocrystalline SiC films could make it a potential candidate in optoelectronic and biomedical applications. Copyright © 2017 VBRI Press.
Giuseppe Napoli; Sabrina Mengaroni; Marco Rallini; Luigi Torre; Andrea Di Schino
Abstract
The present study is focused on analyzing the effect of the interrupted quenching followed by a partitioning process in a high carbon steel 0.50C-1.50Mn-0.40Si-2.00 Cr without significant contribution of Al. Thermal treatments were performed at laboratory scale in a quenching dilatometer Linseis R.I.T.A ...
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The present study is focused on analyzing the effect of the interrupted quenching followed by a partitioning process in a high carbon steel 0.50C-1.50Mn-0.40Si-2.00 Cr without significant contribution of Al. Thermal treatments were performed at laboratory scale in a quenching dilatometer Linseis R.I.T.A RL78. The fractions of retained austenite were evaluated by scanning electron microscope. The temperature for the interrupted quenching phase was evaluated based on the Koistenen and Marburger equation (adapted to the 0.50C steel) and the result highlights a correlation between the chosen different temperature of quenching and the fraction of retained austenite formed during the quenching step of the process. Copyright © 2017 VBRI Press.
c. Amirtha Kumar; R. Mohan Kumar
Abstract
Third order nonlinear optical semi-organic potassium hydrogen maleate single crystal was grown by Sangaranarayanan-Ramasamy (SR) method. The formation of the bonds in the crystal was confirmed by FTIR analysis. Thermal properties were analyzed, and found that the grown crystal is thermally stable up ...
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Third order nonlinear optical semi-organic potassium hydrogen maleate single crystal was grown by Sangaranarayanan-Ramasamy (SR) method. The formation of the bonds in the crystal was confirmed by FTIR analysis. Thermal properties were analyzed, and found that the grown crystal is thermally stable up to 196°C. The transparency (74%) was assessed from the UV-Vis studies. The photo-luminescence spectral study revealed yellow emission in the wavelength region 500-650nm. The surface laser damage threshold value of the grown crystal was measured by using Nd:YAG laser. Z-scan technique was employed to observe the third-order nonlinear optical property of the grown crystal.
Mohan Kumar; Mahima Kaushik; Shrikant Kukreti
Abstract
Electrochemical biosensors (an integrated system of biological constituent and physiochemical detector) have attracted plenty of attention due to its high precision, and importance in clinical diagnosis. In electrochemical biosensors, redox indicators like methylene (MB) blue are used to detect the electrical ...
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Electrochemical biosensors (an integrated system of biological constituent and physiochemical detector) have attracted plenty of attention due to its high precision, and importance in clinical diagnosis. In electrochemical biosensors, redox indicators like methylene (MB) blue are used to detect the electrical changes, which by intercalating between DNA base pairs, can produce an intense redox signal on the surface of ssDNA modified electrode. This study reports the interaction between calf thymus DNA (ctDNA) and new methylene blue (NMB), having almost identical basic skeleton to MB. Various techniques like UV-Visible, thermal melting, fluorescence, circular dichroism (CD) spectroscopy and molecular docking have been utilized. Hypochromism and a red shift in UV-Vis spectra revealed the intercalation binding mode for DNA-NMB complex. Nearly identical binding constants were calculated using UV-Visible and fluorescence spectroscopy. The calculated thermodynamic parameters like change in enthalpy (ΔH°) and entropy (ΔS°) were found to be -6.11×104 and -128.96 JK-1mol-1 at 290 K respectively. CD revealed a change into more compact B-DNA conformation after binding with NMB. These studies suggest that intercalation mode, hydrogen bonding, and van der Waals forces might be responsible for DNA-NMB interaction. This work might further facilitate our understanding about DNA-drug interactions for utilizing them for medicinal purposes and nanochemistry.
Amer Eid Amer; Min Y. Koo; Soon H. Hong
Abstract
This work reports the results of an investigation of micro-alloyed steel plates subjected to high heat input (4.5 kJ/mm), simulating the thermal cycle of heat affected zone (HAZ) conducted by induction heating in a computer controlled weld thermal cycle simulator. Three samples of steels having Carbon ...
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This work reports the results of an investigation of micro-alloyed steel plates subjected to high heat input (4.5 kJ/mm), simulating the thermal cycle of heat affected zone (HAZ) conducted by induction heating in a computer controlled weld thermal cycle simulator. Three samples of steels having Carbon and Nickel content of 0.08 and 0.8 wt. %, respectively, as well as different Aluminum contents of 0.004, 0.026, and 0.057 wt. %, were investigated. The variation in microstructure, hardness and crack tip opening displacement (CTOD) fracture toughness properties with Al contents were evaluated, and compared with another set of the three samples of steel having the same chemical compositions but with neglected amount of Ni content. The fracture toughness tests revealed the decrease in their CTOD values due to increasing Al contents. In contrast, the hardness measuring revealed the increase of the hardness due to increasing Al wt. %. On the other hand, it was found that the presence of 0.8 wt. % Ni promotes the formation of finer microstructure at a high heat input of 4.5kJ/mm, which leads to higher fracture toughness CTOD value(δ =1.05), which is two times the value of those which have traces of Ni content(δ =0.52). However, the hardness test results showed similar values in each case regardless the amount of Ni contents. Meanwhile, the aspect ratio of the nucleated acicular ferrite was found to be increasing together with the refinement of its grain size due to Ni addition. Hence, it can be concluded that such development and the specific additions of Aluminum positively affects the microstructures and mechanical properties of the investigated steels and their used as marine structural steel. Copyright © 2016 VBRI Press.
Dasharath S M; Suhrit Mula
Abstract
The microstructural evolution and mechanical properties of cast brass (Cu-10% Zn) subjected to cumulative strains of 3.0, 5.4 and 7.2 through multiaxial forging (MAF) at cryogenic temperature (77 K) were investigated. The mechanical properties of the homogenized and MAF treated alloy were measured through ...
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The microstructural evolution and mechanical properties of cast brass (Cu-10% Zn) subjected to cumulative strains of 3.0, 5.4 and 7.2 through multiaxial forging (MAF) at cryogenic temperature (77 K) were investigated. The mechanical properties of the homogenized and MAF treated alloy were measured through Vickers hardness testing. The brass deformed up to a cumulative strain of 7.2 showed improvement in the hardness of 2.3 GPa as compared with the as-homogenized annealed (0.55 GPa) alloy. The microstructural evolutions of cryoforged samples were characterized by optical microscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD). Thereby, it helps to increase twining activity for further deformation. TEM and AFM investigations confirmed that the formation of subgrains as well as nanotwins is responsible for the improvement of the mechanical properties. Copyright © 2018 VBRI Press.
Akshay S. Kulkarni; Geeta Shirnalli; Ashok M. Sajjan; Nagaraj R. Banapurmath; Ashok S. Shettar; Kartik J. Uttarkar
Abstract
A solution technique was adopted to develop membranes in which chitosan-wrapped silver nanoparticles (CS-wrapped Ag nanoparticles) were incorporated in poly(vinyl alcohol) (PVA). The morphological studies and the chemical compositions of the prepared membranes were investigated using the characterization ...
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A solution technique was adopted to develop membranes in which chitosan-wrapped silver nanoparticles (CS-wrapped Ag nanoparticles) were incorporated in poly(vinyl alcohol) (PVA). The morphological studies and the chemical compositions of the prepared membranes were investigated using the characterization techniques like Infrared Spectroscopy, Differential scanning colorimetry, Wide Angle X-ray Diffraction, Thermogravimetric analysis and scanning electron microscopy. The effects of CS-wrapped Ag nanoparticles on membrane swelling were systematically studied to know the gas separation performance of the membranes. TGA showed increased thermal stability of Ag-nanoparticles incorporated PVA membranes nearly twice that of plane PVA membranes. Further, SEM revealed that CS-wrapped Ag nanoparticles incorporation into the PVA membrane matrix showed good compatibility and high swelling properties.
E. Murugan; S. Santhosh Kumar; A. Raman
Abstract
New efficient surface enhanced raman scattering (SERS) nanocomposite material namely silver nanoparticles (AgNPs) decorated Cerium Oxide (AgNPs@CeO2) was synthesized by adopting simple citrate reduced, precipitation and deposition methods. The synthesized AgNPs@CeO2 material was characterized with ...
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New efficient surface enhanced raman scattering (SERS) nanocomposite material namely silver nanoparticles (AgNPs) decorated Cerium Oxide (AgNPs@CeO2) was synthesized by adopting simple citrate reduced, precipitation and deposition methods. The synthesized AgNPs@CeO2 material was characterized with UV-DRS, FTIR, Raman, FESEM, EDX and HRTEM analyses. The obtained results reveal the formation of AgNPs@CeO2 nanocomposite material with high purity. The FESEM image result confirms that the Ag NPs are decorated on the surface of CeO2. This AgNPs@CeO2 nanocomposite was used for fabrication of SERS substrate by drop casted on glass slide. Similarly, for comparative purpose, the pure AgNPs and CeO2NPs were also fabricated individually on glass slide. The SERS properties for newly fabricated AgNPS@CeO2, AgNPs and CeO2 NPs substrate were examined by employed in to detection of 4-aminothiophenol (4-ATP) as a model Raman reporter molecule/analyte. The newly designed AgNPs@CeO2 material showed excellent SERS properties and sensitivity than that of AgNPs and CeO2NPs substrates. The enhanced SERS properties noticed in AgNPs@CeO2 are due to the charge transfer, electromagnetic effect and more hot spots present in metal on metal oxide surfaces. Therefore, it is suggested that the AgNPs@CeO2 composite material with excellent SERS properties will have an intensive scope for detection of medically significant single analyte/molecule and hence study in that direction are continuing. Copyright © 2018 VBRI Press.
Deepika Gupta; Patima Chauhan
Abstract
Biologically manufactured silver nanoparticles are increasingly being used for various sterilization purposes because of its broad spectrum antibacterial activity. There have been relatively few studies on the applicability of silver NPs to control plant diseases. The present study was aimed to investigate ...
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Biologically manufactured silver nanoparticles are increasingly being used for various sterilization purposes because of its broad spectrum antibacterial activity. There have been relatively few studies on the applicability of silver NPs to control plant diseases. The present study was aimed to investigate the potential of green synthesized silver nanoparticles (GAgNPs) to analyze disease burden in poppy plants affected with Downy mildew (DM) disease caused by fungi Peronospora arborescens for the first time. The GAgNPs was also assayed to determine its antimicrobial potential against bacterial strains. We found that there were some bacterial strains in addition to the fungus which affected the crop yield, by measuring colony forming unit (CFU), caused disease burden on poppy plants. In in vitro examination shows, GAgNPs significantly inhibited bacterial strains even at 10 ppm (least minimum inhibitory concentration (MIC)) then control. Maximum inhibition shows at 100 ppm (most MIC) which is an optimize concentration of GAgNPs. These results suggest that GAgNPs have potential for use as economic, low-dose, potentially non-persistent anti-microbial agents against both DM fungi and the bacterial strains. Copyright © 2017 VBRI Press.
M.V.L. Kumari; A. Kaviarasi; A.R. Prabakaran; A. Anandavadivel
Abstract
A polymer is a giant molecule, made of many repeated subunits. Titled material Epoxy resin is a polymer. Films of epoxy resin with curing agents are prepared by wt/wt ratio. The concentrations of both the polymer and curing agents are varied. Organic solvents - Triethylenetetramine and Diethylenetriamine ...
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A polymer is a giant molecule, made of many repeated subunits. Titled material Epoxy resin is a polymer. Films of epoxy resin with curing agents are prepared by wt/wt ratio. The concentrations of both the polymer and curing agents are varied. Organic solvents - Triethylenetetramine and Diethylenetriamine are curing agents used in this study. Films are casted by solvent evaporation technique. Films of epoxy resin with different curing agents are subjected to spectroscopic, mechanical and dielectric studies. From the studies better curing agent is traced out. Copyright © VBRI Press.
G.A. Suganya Josephine; K. Jayaprakash; A. Sivasamy
Abstract
Heterogeneous semiconductor nanomaterials are widely employed nowadays as efficient photocatalysts for selective organic transformation reactions. A co-precipitation technique was employed for the preparation of ZnO doped dysprosium oxide from the respectivemetal nitrates and characterization studies ...
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Heterogeneous semiconductor nanomaterials are widely employed nowadays as efficient photocatalysts for selective organic transformation reactions. A co-precipitation technique was employed for the preparation of ZnO doped dysprosium oxide from the respectivemetal nitrates and characterization studies were conductedby FT-IR, X-Ray Differaction, UV-Visible-DRS and FE-SEM analysis. XRD showed the prepared nanomaterial to be in a nano range with high crystallinity. The particles possesed a spherical morphology and of the order of 40-50 nm(particle size) as evidenced from FE-SEM analysis. From theUV-Visible-DRS analysis the band gap energy was calculated as 3.15 eV. The synthesizedZnO doped dysprosium oxide was employed as a photocatalyst under UV light irradiation for selective organic transformation reaction. Quinones especially benzoquinones are a class of compounds which forms a basic structural skeleton for various natural compounds. They are widely employed asa precursor for natural products synthesis. Herein we report the synthesis of N-phenyl-p-benzoquinonimine from diphenylamine by employing ZnO doped dysprosium oxide as a photocatalyst under UV light irradiation in ethanol. Thin Layer Chromatography was used to check the progress of the reaction. Optimization studies for the reaction parameters were conducted systematically.
Sumali Bansal; . Priyanka; Rajiv Bhandari; Keya Dharamvir
Abstract
Gold clusters are known to have size dependent geometries. The study of golden cages of different sizes and dimensions has gained momentum in recent years as they can accommodate guest atoms to form a new kind of endohedral structure. We will be studying the doping of gold tubular cages with transition ...
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Gold clusters are known to have size dependent geometries. The study of golden cages of different sizes and dimensions has gained momentum in recent years as they can accommodate guest atoms to form a new kind of endohedral structure. We will be studying the doping of gold tubular cages with transition metal (TM=Ag, Cu and Au). Their geometrical structures, relative stabilities, binding energies and bond lengths are studied using Model Potential approach- Gupta Potential (GP). AuAg and AuCu have been chosen because they may be expected to show different behaviors. As far as our knowledge no such work has been reported earlier. It is observed that doping of Ag and Cu atom at the centre of planar Au6 results in a three dimensional geometry. The atom-atom interaction potential predicts the dominance of the finite size effect as the number of Cu and Ag atoms increases along with the size of gold tubular cage. Copyright © 2018 VBRI Press.
James Mathew; Animesh Mandal; Jason Warnett; Mark A. Williams; M. Chakraborty; Prakash Srirangam
Abstract
The present work compares the 2D and 3D distribution of TiB2 particles in a semisolid processed Al-4.5%Cu-5wt.% TiB2 in-situ composite prepared by flux assisted synthesis. The composite was synthesized by the reaction of K2TiF6 and KBF4 salts in molten Al-4.5Cu alloy held at 800 oC for an hour. The extent ...
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The present work compares the 2D and 3D distribution of TiB2 particles in a semisolid processed Al-4.5%Cu-5wt.% TiB2 in-situ composite prepared by flux assisted synthesis. The composite was synthesized by the reaction of K2TiF6 and KBF4 salts in molten Al-4.5Cu alloy held at 800 oC for an hour. The extent of distribution of TiB2 particles was investigated using Field Emission Scanning Electron Microscopy (FESEM) and X-ray computed tomography (XCT) to obtain 2Dand 3D images respectively. The studies indicated improved distribution of TiB2 particles after semi-solid forging of composites (at 0.1 volume fraction of liquid and 50% reduction) as compared to as cast composites. The hardness of the semisolid forged composites showed a significant increase and is uniform in all directions. The increase in hardness could be attributed to particle fragmentation and its redistribution in the matrix. Further investigation will be needed to understand the mechanism of redistribution and investigate the mechanical properties of such composites in detail. Copyright © 2016 VBRI Press.
Niranjana M; Sharanappa Chapi; Yesappa L; Archana K; Raghu S; Devendrappa H
Abstract
Polyaniline (PANI) composites doped with Vanadium pentoxide (V2O5) of different weight percentage using dodecylbenzene sulfonic acid (DBSA) as surfactant was prepared by in-situ chemical oxidation reaction method. Here ammonium persulphate was used as an oxidizing agent. The formation of composite (PANI/DBSA/V2O5) ...
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Polyaniline (PANI) composites doped with Vanadium pentoxide (V2O5) of different weight percentage using dodecylbenzene sulfonic acid (DBSA) as surfactant was prepared by in-situ chemical oxidation reaction method. Here ammonium persulphate was used as an oxidizing agent. The formation of composite (PANI/DBSA/V2O5) was confirmed with the help of analytical studies like scanning electron microscopy (SEM) and UV/Vis spectroscopy. SEM images show a substantial change in PANI morphology after incorporation of vanadium pentoxide. The optical characterizations by UV-Vis absorption spectroscopy show the increased absorption with addition of V2O5. The electrical conductivity has been studied in the frequency range of 20 Hz to 1MHz and it is found that PANI/DBSA:2%(V2O5) shows high electrical conductivity compared to pure PANI and other composites. It is observed that the dielectric constant and dielectric loss increase with concentration of V2O5. PANI/DBSA/V2O5 composites are most promising material for many electrical and potential applications. This semiconducting polymer combination of PANI and Vanadium pentoxide (V2O5) which produce hybrid material, behaves as semiconductor at low temperatures; this behavior is predicted by results of dielectric properties studied. Copyright © 2017 VBRI Press.
N. Sivasankarareddy; R. Viswanatha; B. Sujatha; C. Narayanareddy
Abstract
Correlation between mechanical properties and MAS NMR spectroscopic revelations have been carried out on the glass system, xZnO – 50 B2O3 – (50 – x) V2O5 where 15 ≤ x ≤ 40 is prepared by a novel microwave heating method. Elastic moduli were computed from ultrasound velocities ...
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Correlation between mechanical properties and MAS NMR spectroscopic revelations have been carried out on the glass system, xZnO – 50 B2O3 – (50 – x) V2O5 where 15 ≤ x ≤ 40 is prepared by a novel microwave heating method. Elastic moduli were computed from ultrasound velocities measured by a pulse echo superposition method. Both ultrasound velocities and elastic properties increase monotonically as a function of ZnO content. The variations observed in the mechanical properties were explained in view of modifications occur in the network structure consisting of borovanadate units. The bulk and shear moduli increase due to the presence of four coordinated borons along with diborovanadate units, which increases the dimensionality and connectivity of the glass network. Surprisingly, the process of the reconversion of four coordinated borons into three coordinated borons beyond 33.3mol% of modifier concentration is not initiated in these glasses, which is essentially due to the formation of [B2V2O9]2- units similar to the [B4O7]2-units. This is well supported by the monotonic increase in N4 - values even above the 33.3 mol%of modifier content. Materials with enhanced elastic properties find application in cathode materials. Copyright © 2017 VBRI Press.
Subhashree Patra; Pinaki Chatterjee; Kamal L. Mohanta; Chhatrapati Parida
Abstract
Modification of surface of natural fiber by gamma irradiation is an effective and economical technique and of viable interests in the terrain of biocomposites. The response of doses (0.5 Gy,1Gy and 2 Gy) of gamma irradiation of 6MV energy on the structural, tensile and flexural ...
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Modification of surface of natural fiber by gamma irradiation is an effective and economical technique and of viable interests in the terrain of biocomposites. The response of doses (0.5 Gy,1Gy and 2 Gy) of gamma irradiation of 6MV energy on the structural, tensile and flexural properties of composites using poly lactic acid (PLA) and fibers of luffa cylindrical (LC) is studied. Preliminary results suggests promising mechanical properties. After reinforcement of irradiated LC fiber, the tensile strength and flexural strength of the virgin PLA matrix increases by 60% and 155% respectively. The E-modulus of the composites are also heightened with addition of irradiated fiber up to the limit of 1 Gy of irradiation dose and then decreases with higher dose of irradiation. Furthermore the tensile strength and flexural strength of the composites increases with incorporation of very low content of LC fiber up to 2wt% and decreases with higher loading of fibers (5wt% and 10wt%). Modulus of composites is enhanced with increase in wt of fiber content in the composites. Moreover beefore reinforcement the LC fibers are modified with Ca salts in order to explore the use of these composites in biomedical territory. Copyright © 2018 VBRI Press.
Ajay S. Utiye; Sanjay Kumar Awasthi; S. K. Bajpai; B. Mishra
Abstract
The method of preparation of Gelatin/poly (aniline) composite films has been discussed. Gelatin was cross linked with glyoxal (Glox) in aqueous medium. The composite film was prepared by in-situ polymerization of Aniline within the Gelatin film matrix. The films so prepared have been characterized with ...
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The method of preparation of Gelatin/poly (aniline) composite films has been discussed. Gelatin was cross linked with glyoxal (Glox) in aqueous medium. The composite film was prepared by in-situ polymerization of Aniline within the Gelatin film matrix. The films so prepared have been characterized with XRD, tensile testing and conductivity measurements. The variation in mechanical/electrical properties of Gelatin/poly(aniline) composite films with varying concentration of aniline have been investigated. It was observed that the electrical conductivity of the films increase appreciably with the concentration of aniline in the film. In addition, the tensile strength of the films was also found to increase with aniline concentration. The results from XRD, conductivity test and tensile testing were correlated. A stronger material having added advantage of conductivity has been reported. Copyright © 2017 VBRI Press.
María N. Delpupo; Mariano N. Inés; Graciela A. Mansilla
Abstract
Hydrogen embrittlement is a common, dangerous, but poorly understood cause of failure in metals and alloys. In coated samples, coatings act as a barrier to hydrogen damage resulting in a decrease in the corrosion rate and consequently reducing hydrogen embrittlement. In order to obtain an effective barrier ...
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Hydrogen embrittlement is a common, dangerous, but poorly understood cause of failure in metals and alloys. In coated samples, coatings act as a barrier to hydrogen damage resulting in a decrease in the corrosion rate and consequently reducing hydrogen embrittlement. In order to obtain an effective barrier against the hydrogen income the layer must be continuous, impermeable and stable in the environment so adequate variable control must be followed. Knowledge about absorption/desorption energies of hydrogen from traps as a function of temperature help to design proper thermal treatments to eliminate it. This paper represents a survey about variables involved at each electroplating stage and hydrogen income into steel wires, analyzed through optical microscopy, scanning electron microscopy and thermal analysis. Copyright © 2018 VBRI Press.
Vinod Karar; Amit L Sharma
Abstract
Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being ...
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Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being reflected and transmitted by various interfaces where it is split by percentage of overall intensity or wavelength. In this study, design and fabrication of a dichroic optical beam splitter for filtering of red and green light from a white light source has been presented. Here, a symmetric dielectric multilayer stack with 15 alternating layers of alumina and silica are deposited on BK-7 glass using e-beam evaporation technique. High and low refractive indices of 1.63 and 1.46 respectively are used with quarter-wave optical thicknesses of layers. The beam splitter is designed for 45 ̊ angle of incidence using FilmstarTM design software. Transmission spectrum obtained from UV-Vis-NIR double beam spectrophotometer shows reflectance of ~54% at 660 nm (red wavelength region) and transmittance of ~88% at 550 nm (green wavelength region). The coated sample is further subjected to adhesion and hardness test according to MIL standard and no peel off or scratch is observed indicating excellent durability of the coating. The modelled and measured results closely agree with one another over visible spectral regions. Copyright © 2017 VBRI Press.
Elena Brandaleze; Martina Avalos; Mykaylo Romanyuk
Abstract
Steel wires under severe cold drawing deformation, develop high strength (5-6 GPa) and ductility. For these reasons it is relevant to increase the knowledge on the structural evolution and deformation mechanisms involved during wire drawing process, due to their critical applications such as bridges, ...
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Steel wires under severe cold drawing deformation, develop high strength (5-6 GPa) and ductility. For these reasons it is relevant to increase the knowledge on the structural evolution and deformation mechanisms involved during wire drawing process, due to their critical applications such as bridges, cranes and tire cord. This paper presents a comparative study of steel wires (0.84%C) at different deformation stages. The product presents a normal behaviour under torsion test, the mentioned test is normally used to corroborate the wire aptitude. The main objective of the study is to increase the knowledge on the structural evolution after cold drawn considering the deformation mechanisms, cementite dissolution, and epsilon carbide precipitation. The microstructural study was carried out applying light and scanning electron microscopy (SEM-EBSD). The structural information was correlated with results of differential thermal analysis (DTA) and FactSage simulation. The structural study verified the presence of curling phenomenon in the wires. The interlaminar spacing (l) and the thickness of cementite lamellae in wires cold drawn from 8 mm up to 2 mm of diameter was determined. Finally, the dynamic strain aging, which is promoted by cementite destabilization and the precipitation of epsilon carbide was studied. Copyright © 2018 VBRI Press.
Anupma Sharma; Vijay Kumar; Saurav Kumar; Pooja D; Sudeshna Bagchi; Amol P. Bhondekar
Abstract
In this work, we present the first investigations of Mn3O4 nanoparticles doped in polyaniline (PANI) matrix for gas sensing application. PANI/Mn3O4 nanocomposite (NC) was synthesized by facile one step reduction method with varied dopant concentrations (1mM and 3mM) of synthesized Mn3O4 nanoparticles ...
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In this work, we present the first investigations of Mn3O4 nanoparticles doped in polyaniline (PANI) matrix for gas sensing application. PANI/Mn3O4 nanocomposite (NC) was synthesized by facile one step reduction method with varied dopant concentrations (1mM and 3mM) of synthesized Mn3O4 nanoparticles followed by its characterization for optical, structural, morphological, thermal and electrical properties. Optical characterization by UV-Vis and FT-IR confirmed the doping of Mn3O4 in polymer matrix. TGA analysis showed improvement in the thermal stability of the NC. SEM images portrayed agglomerated morphology of PANI whereas the NC depicted fibre-like structures symptomatic of more porosity. Gas sensing behavior was investigated towards acetone, ethanol and benzaldehyde vapours. The sensor with 3mM dopant concentration exhibited significant sensing response with a sensitivity of 1.5 at room temperature towards acetone vapour, which can be attributed to the controlled and improved properties at the interface via molecular and supramolecular interactions. The synthesized NC has a potential use as acetone sensor with fast response and recovery. Copyright © 2017 VBRI Press
Aboo Bakar Khan; Mohini Sharma; Syed Gulraze Anjum; Mohd Jawaid Siddiqui
Abstract
In this work, we have performed the influence of back barrier layer thickness variation on AlGaN/GaN Metal Oxide Semiconductor High Electron Mobility Transistor (MOS-HEMT) device with 0.5 µm Schottky gate length. The AlGaN back barrier layer presented increases the conduction band with respect ...
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In this work, we have performed the influence of back barrier layer thickness variation on AlGaN/GaN Metal Oxide Semiconductor High Electron Mobility Transistor (MOS-HEMT) device with 0.5 µm Schottky gate length. The AlGaN back barrier layer presented increases the conduction band with respect to GaN channel layer so that more no of electron confinement into the GaN channel layer and improve the high-frequency performance. The effect of the back-barrier layer thickness is performed by using 2-D TCAD Atlas Silvaco numerical simulation tool by taking Hydrodynamic mobility model. Due to a large amount of two-dimensional electron gas (2-DEG) density at the AlGaN/GaN heterointerface of the MOS-HEMT device higher drain current density is obtained. The 2-D simulation is carried out with a variation of back barrier layer thickness for various device parameter such as transfer characteristics (Id-Vg), drain current with a drain voltage (Id-Vd), transconductance (gm), drain induced barrier lowering (DIBL), conduction band energy and electron concentration into the channel. In this simulation, we have also performed the RF performance like a gate to source capacitance (Cgs) and current gain cut-off frequency of AlGaN/GaN MOS-HEMT device. The results obtained by variation of AlGaN back barrier layer thickness can be a better solution in future analog and RF device application. Copyright © 2018 VBRI Press.
M. K. Gupta; Kunwar Rohit
Abstract
In present work, epoxy based glass composite is prepared using hand lay-up method followed by static compression with varying numbers of woven glass layers. Dynamic mechanical properties of prepared glass composites are studied in terms of storage modulus (E'), loss modulus (E''), damping (Tand) and ...
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In present work, epoxy based glass composite is prepared using hand lay-up method followed by static compression with varying numbers of woven glass layers. Dynamic mechanical properties of prepared glass composites are studied in terms of storage modulus (E'), loss modulus (E''), damping (Tand) and glass transition temperature (Tg) as a function of temperature. The results indicated that value of E' and Tg increases whereas value of Tand decreases as increase in temperature. In addition, value of Tg obtained from Tand curve is found lower than that obtained from peak of E'' curve. The present glass composites are suitable for constructions, automobiles and aerospace industries due to its better dynamic mechanical properties and thermal stability. Copyright © 2017 VBRI Press.
Raviraj M. Kulkarni; Ramesh S. Malladi; Manjunath S. Hanagadakar
Abstract
Liquid Impregnation (LI) technique was developed to prepare 1% and 2% Ag doped Titania nanoparticles. The characterization of the prepared nanoparticles was achieved by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission Electron Microscopy ...
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Liquid Impregnation (LI) technique was developed to prepare 1% and 2% Ag doped Titania nanoparticles. The characterization of the prepared nanoparticles was achieved by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission Electron Microscopy (TEM). The crystallite size was obtained by Scherrer equation analysis of XRD main peak of doped and undoped nanoparticles. It was observed that crystallite size of bare TiO2 was 17.00 nm, whilst the crystallite size of 1% Ag doped titania and 2% Ag doped titania was 13.07 nm to 14.17 nm. TEM images ascertained that particle size of Ag-TiO2 nanoparticles were in the range 40-45 nm in length and 10-15 nm in width. The pH of the solution exerted a negative effect on photodegradation rate of sparfloxacin. The masking effect on the degradation of sparfloxacin was observed at higher catalyst dosages. The increase in UV intensity linearly enhanced the degradation rate of sparfloxacin and the influence of initial sparfloxacin concentration on the degradation rate was investigated and discussed. Copyright © 2018 VBRI Press.
R Subba Reddy; S Uthanna; A Sivasankar Reddy; T. Srikanth; B. Radha Krishna
Abstract
Zinc oxide thin films were deposited by RF magnetron sputtering on p-type (100) silicon and glass substrates held at room temperature by varying the oxygen partial pressures and the optimized films was annealing at different temperatures. The deposition rate of the films was decreased from 5.8 to 2.5 ...
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Zinc oxide thin films were deposited by RF magnetron sputtering on p-type (100) silicon and glass substrates held at room temperature by varying the oxygen partial pressures and the optimized films was annealing at different temperatures. The deposition rate of the films was decreased from 5.8 to 2.5 nm /min with increase of oxygen partial pressures. X- ray diffraction results reveal that the films deposited at oxygen partial pressure of 2x10-2 Pa the (100) preferred orientation peak crystallinity became better. Raman spectroscopy analysis shows an improvement in the crystalline quality of the films at 2x10-2 Pa. Fourier transform infrared spectroscopy of ZnO films confirms the presence Zn-O bonding. The nanorods were observed at oxygen partial pressure of 5x10-2 Pa. The maximum transmittance of 97% and crystallite size of 21 nm was observed at oxygen partial pressure of 2x10-2 Pa. The as deposited films annealed at 473 K the intensity of (100) phase was decreased. The RMS roughness of the as deposited ZnO films was 7.3 nm, and it increased to 30 nm for the films annealed at 473K. Optical spectra revealed the films annealed at 673 K show the optical band gap of 3.17 eV. Copyright © 2018 VBRI Press.
