Ahmed A. Al-Ghamdi; Omar A. Al-Hartomy; Falleh R. Al-Solamy; Nikolay Dishovsky; Radostin Nickolov; Nikolay Atanasov; Kamelia Ruskova
Abstract
The purpose of the study is to synthesize nanosized magnetite in situ the nanosized porous texture of activated carbons and to examine the impact of the resulting hybrid filler upon the microwave properties and electromagnetic interference shielding effectiveness of composites based on natural rubber. ...
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The purpose of the study is to synthesize nanosized magnetite in situ the nanosized porous texture of activated carbons and to examine the impact of the resulting hybrid filler upon the microwave properties and electromagnetic interference shielding effectiveness of composites based on natural rubber. The fillers have been characterized by X-ray diffraction and photoelectron spectroscopy establishing the influence of the magnetite layer on the texture characteristics. Studies have been carried out on the effect that the fillers synthesized have on the microwave properties, the real and imaginary part of the permittivity and permeability as well as on the dielectric and magnetic loss angle tangent of the composites. It has been found that filler comprising externally about 5% of magnetite phase is the most effective. The introduction of the magnetic phase contributes to the improvement in the microwave characteristics and expanding the frequency range in which the composites are of good microwave properties due to the combination of high dielectric and the high magnetic losses. Copyright © 2017 VBRI Press.
Deepika Chaudhary; Mansi Sharma; S. Sudhakar; Sushil Kumar
Abstract
In this article, we report the phase transition region of hydrogenated amorphous (a-Si:H) to nano-crystalline (nc-Si:H) silicon thin films deposited using 27.12 MHz assisted Plasma Enhanced Chemical vapor Deposition (PECVD) process with the approach of plasma diagnosis. This work presents for the first ...
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In this article, we report the phase transition region of hydrogenated amorphous (a-Si:H) to nano-crystalline (nc-Si:H) silicon thin films deposited using 27.12 MHz assisted Plasma Enhanced Chemical vapor Deposition (PECVD) process with the approach of plasma diagnosis. This work presents for the first time a study of plasma characteristics using Impedance Analyser (V/I probe) at various applied power (4 W - 40 W), though till now this apparatus has been utilized only to analyse the applied delivered power during processing. On the basis of plasma diagnose, optimum bulk field (5 V/cm); sheath field (1376 V/cm) and minimum sheath width (7.4 x 10-4 cm) observed at 20 W power which provides a visible mark of transition from a-Si:H to nc-Si:H. On account of plasma properties, the deposition was carried out by considering the plasma-surface interaction during growth. The microstructure of the deposited films was characterized using Raman spectra, UV-Vis spectra and conductivity measurements and they were found to be well correlating with the evaluated plasma characteristics. In particular, it was found that at applied power near to the onset of transition regime i.e. at 10 W, preeminent properties of a-Si:H film was observed, predominantly in terms of highest photosensitivity (7.2x103), low photo-degradation and high deposition rate (~1.39 Å/s). On the other hand, volume fraction of crystallites (24 %), wider band gap (2.0 eV) and no photo-degradation observed for the film deposited at 20 W applied power which signifies the existence of crystallites in an amorphous matrix. Copyright © 2017 VBRI Press.
Michael Schoeler; Philipp Schuh; Grazia Litrico; Francesco La Via; Marco Mauceri .; Peter J. Wellmann
Abstract
In this article, sublimation growth of 3C-SiC on 3C-SiC-on-Si seeding layers was evaluated by characterizing the densities of protrusions and stacking faults (SF). Both defects are among the most critical concerning the growth process and the realization of high quality material for device applications. ...
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In this article, sublimation growth of 3C-SiC on 3C-SiC-on-Si seeding layers was evaluated by characterizing the densities of protrusions and stacking faults (SF). Both defects are among the most critical concerning the growth process and the realization of high quality material for device applications. By variation of growth parameters like temperature, growth rate and 3C-SiC-thickness we conducted a series of experiments and characterized these layers by optical microscopy and KOH etching. The protrusion density is predetermined by the seeding layers and was kept at a constant level, whereas a decrease of SF-density was observed with increasing layer thickness during subsequent sublimation growth steps. Therefore, in the case of Sublimation Epitaxy (SE) it has been found appropriate to distinguish between defects that can be reduced during SE and defects that are merely reproduced from the seeding material during sublimation growth. Furthermore, a weak trend towards a decrease of SF-density with increasing growth temperature was observed. The findings in this work demonstrates the potential of SE in growing thick and high-quality 3C-SiC layers if sufficiently good seeding layers were available. Copyright © 2017 VBRI Press.
Suhad Sbeih; Werner Steffen; Michael Kappl
Abstract
The demand for new advanced functional materials has driven scientific work over the past decades. Nature has been inspiring in the creation of different types of self-cleaning and super repellent surfaces mimicking those of plants (lotus leaves), animals (shark skin) or insects (butterfly wings, water ...
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The demand for new advanced functional materials has driven scientific work over the past decades. Nature has been inspiring in the creation of different types of self-cleaning and super repellent surfaces mimicking those of plants (lotus leaves), animals (shark skin) or insects (butterfly wings, water strider). To produce and maintain super repellent materials, chemical modification of the surface by using low surface energy materials such as fluoropolymers and/or siloxanes is necessary. Also, physical modification of surface roughness enhances super-repellency against various liquids. The surface roughness can be achieved e.g., by the deposition of nano particles (NPs) using Liquid Flame Spray (LFS). Industrial applications like paper coatings, oil-water separation, and microfluidic devices have benefited from the fabrication of super-hydrophobic surfaces by LFS. In our work, glass substrates were fluorinated by chemical vapor deposition (CVD) method, and others were additionally pre-coated with silica NPs by LFS. The coated glass surfaces were characterized for their anti-wettability by measuring the contact angles of water and compare that to bare glass. The influence of the produced coatings on the wettability of surface with different liquids was examined through measuring advancing/receding contact angles as well as the roll off angle. Results showed that compared to bare glass only fluorination of glass increased the water static contact angle from 18 to almost 112 . This is indicative of hydrophobic behaviour. Coating glass with silica NPs by LFS before fluorination, enhanced the water anti-wetting property for super hydrophobicity. LFS coating provided good oleophobic characteristic.
Bandana Rajpoot; Sushil Kumar Singh; Abhishek Kumar; Anuj Jain
Abstract
This study is focused to see reinforcing effects of SiO2 nanoparticles on the mechanical and thermal properties of epoxy resin. For the same, SiO2 nanoparticles up to 8 wt.% were reinforced in epoxy resin and the effect of this reinforcement was seen on fracture toughness, fracture energy and glass transition ...
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This study is focused to see reinforcing effects of SiO2 nanoparticles on the mechanical and thermal properties of epoxy resin. For the same, SiO2 nanoparticles up to 8 wt.% were reinforced in epoxy resin and the effect of this reinforcement was seen on fracture toughness, fracture energy and glass transition temperature. The particles were dispersed ultrasonically in epoxy resin, which gives well dispersion of nano-SiO2 particles. A good dispersion of silica nanoparticles enhances mechanical and thermal properties up to 4 wt.% SiO2. As a result, the value of fracture toughness increases from 1.10 to 2.90 M Pa.m1/2, fracture energy increases from 2.66 to 11.50 kJ/m2 and glass transition temperature increased about 9°C for the epoxy containing 4 wt.% SiO2 nanoparticles. With further particle loading in epoxy reflected decrease in mechanical and thermal properties, which is attributed to the significant increase in clustering of the nanoparticles at higher loading concentrations.
Manoj D. Shanti; Kaveri D. Shanti; Jyotsna Meshram; Manisha Raut; Kamlakar Nandekar
Abstract
A series of new phenothiazine derivatives of sulfonamide dyes was designed, synthesized & evaluated for their potent anti-cancer activities. The compounds were designed on the basis of molecular docking studies. Firstly they were docked with three different anticancer target enzymes viz. topoisomerase-II, ...
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A series of new phenothiazine derivatives of sulfonamide dyes was designed, synthesized & evaluated for their potent anti-cancer activities. The compounds were designed on the basis of molecular docking studies. Firstly they were docked with three different anticancer target enzymes viz. topoisomerase-II, aromatase and CDK2 and on the basis of dock score the designed compounds were synthesized. All synthesized compounds were bio-evaluated for their in-vitro anti-cancer action which displayed adequate results in agreement with the outcome of docking study.
Kanhaiya M. Dadure; Animeshchandra G. M. Haldar; Debarshi Kar Mahapatra
Abstract
The present investigative studies involve molecular docking study of substituted thiophene-based chalcone compounds (A1-A9) against anti-cancer therapeutic target cyclin-dependent protein kinase-2 (Cdk-2) (PDB ID: 1HCL) for identifying and developing potential inhibitors. Few imperative physicochemical ...
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The present investigative studies involve molecular docking study of substituted thiophene-based chalcone compounds (A1-A9) against anti-cancer therapeutic target cyclin-dependent protein kinase-2 (Cdk-2) (PDB ID: 1HCL) for identifying and developing potential inhibitors. Few imperative physicochemical properties such as stretching, bending, stretching-bending, torsion, Non-1,4 VDW, 1,4 VDW, total steric energy for frame, and total energy of the best inhibitors have also been determined.
k. Velavan; p. Palanisamy; E. Thirukkumaran
Abstract
The mechanical behavior of AMMC based reinforced hybrid composites with various volume fractions of Sic (3, 6, 9, 12, 15) and Gr (1, 2, 3, 4, 5) was studied. The Stir casting method was adapted for manufacturing the various samples. The analysis reveals the increase in strength and hardness of the samples ...
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The mechanical behavior of AMMC based reinforced hybrid composites with various volume fractions of Sic (3, 6, 9, 12, 15) and Gr (1, 2, 3, 4, 5) was studied. The Stir casting method was adapted for manufacturing the various samples. The analysis reveals the increase in strength and hardness of the samples with greater percentage compositions of reinforcements. The study was performed to analyze the micro structural properties of the composites based on the addition of reinforcements. The hardness, tensile strength and impact strength were analyzed. The addition of Sic and Gr proved to enhance density to an optimal range to improve the structural and mechanical property of the reinforced AMCs. The composite with enhanced mechanical property was identified and the test results were verified to establish the alignment of the composite with a wide range of industrial and automotive applications.
Yuvraj S. Malghe; Atul B. Lavand
Abstract
Here, we report on microemulsion synthesis of nitrogen (N) doped TiO2 quantum dots (QDs) with improved visible-light response. XRD, FTIR, XPS, EDX and Raman spectroscopy confirms that N was doped successfully in TiO2 lattice. SEM and TEM study confirms spherical morphology of N-doped TiO2 QDs. N-doped ...
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Here, we report on microemulsion synthesis of nitrogen (N) doped TiO2 quantum dots (QDs) with improved visible-light response. XRD, FTIR, XPS, EDX and Raman spectroscopy confirms that N was doped successfully in TiO2 lattice. SEM and TEM study confirms spherical morphology of N-doped TiO2 QDs. N-doped TiO2 sample exhibit a narrower band gap and stronger visible light absorption as compared to pure TiO2. The assistance of the N enhances the photocatalytic activity in the visible light region by promoting the separation of the photo generated electrons and holes to accelerate the transmission of photocurrent carrier. Photocatalytic activity study evaluated for the degradation of acifluorfen herbicide under visible-light irradiation, demonstrated that N-doped TiO2 sample is more active than pure and commercial TiO2. The high visible-light photocatalytic activity is attributed to the anatase crystalline phase, small crystallite size, strong visible light absorption capacity and superior electron-hole charge carrier’s separation efficiency. The photoluminescence (PL) study was employed to test hydroxyl (•OH) radicals, which show that N-doped TiO2 helps to produce •OH radicals and favors to enhance its photocatalytic activity. N doped TiO2 quantum dots prepared in this work exhibit better photocatalytic activity and hence having a potential to use as a photocatalyst for the degradation of harmful organic chemicals, dyes and drugs coming out from industries and will help to keep environment clean and safe. Copyright © 2016 VBRI Press.
Subhadip Chakraborty; Chirantan Das; Anupam Karmakar; Sanatan Chattopadhyay
Abstract
The impedance, capacitance and conductance of aqueous sucrose polar solution are measured by employing impedance spectroscopy method and the current passing through the system for different DC voltages are measured implementing I-V method. The variation of electrical parameters with sucrose content in ...
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The impedance, capacitance and conductance of aqueous sucrose polar solution are measured by employing impedance spectroscopy method and the current passing through the system for different DC voltages are measured implementing I-V method. The variation of electrical parameters with sucrose content in such solution exhibits a quasi-oscillatory nature, which is attributed to the random orientation of water and sucrose dipoles in the solution and their mutual interactions at the molecular level, including water-water, water-sucrose and sucrose-sucrose dipole interactions. To justify the quasi-oscillatory nature from analytical point of view, a theoretical model is developed on the basis of multi-body dipolar interactions of randomly distributed molecular dipoles. The experimental data agrees well with those obtained from the analytical model. The measurement of electrical parameters is performed within a frequency window of 100 Hz to 4 MHz for volume fractions of sucrose with respect to water, ranging from 0.1 to 0.6. The impedance, capacitance and conductance are obtained to be in the range of 0.907 k – 281 k, 38 pF – 266 pF, and 3 µS – 55 µS respectively for the sucrose volume fraction range considered. Current voltage measurements for the same concentration range are performed for a voltage swing between ±5 V and the obtained values vary from +20 µA to -25 µA. The study represents a deterministic approach to analyze the effective nature of a sucrose solution in terms of dielectric polarization of the system which finds application in sucrose quality assessments.
Archana Sharma; Anu .; Mushahid Husain; Anurag Srivastava; Mohd. Shahid Khan
Abstract
Surface metal adsorption on 2D structures is demonstrated to be an effective tool for improving hydrogen storage capacity. In the current work, the behavior of Ca atom adsorption on monolayer MoS2 is studied and subsequently its hydrogen storage capacity is investigated computationally using van der ...
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Surface metal adsorption on 2D structures is demonstrated to be an effective tool for improving hydrogen storage capacity. In the current work, the behavior of Ca atom adsorption on monolayer MoS2 is studied and subsequently its hydrogen storage capacity is investigated computationally using van der Waals (vdW) revised Density Functional Theory. It is found that the Ca binds strongly with the MoS2 monolayer without being clustered, leading to high hydrogen storage capacity. It is further shown that five hydrogen molecules to each Ca atom can be adsorbed with the average adsorption energy of 0.23eV per hydrogen molecule, indicating it to be a good choice for reversible adsorption/desorption of H2 molecules at ambient conditions. It is revealed that hybridizations between s orbitals of H2 and p orbitals of S are also responsible for adsorption mechanism, along with coulomb interactions. It is demonstrated that a steady and uniform high Ca coverage can be achieved without clustering and with enhanced binding energy which can be used as high hydrogen capacity storage system. Copyright © 2018 VBRI Press.
Masashi Hatanaka
Abstract
A useful formulation of ion-adsorption kinetics is introduced based on our recent researches. The chemical reaction kinetics and diffusion kinetics are simultaneously analyzed combining with the Einstein’s viscosity formula. The rate-determining steps are quantitatively determined by estimating ...
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A useful formulation of ion-adsorption kinetics is introduced based on our recent researches. The chemical reaction kinetics and diffusion kinetics are simultaneously analyzed combining with the Einstein’s viscosity formula. The rate-determining steps are quantitatively determined by estimating the relative magnitude of the kinetics resistances in the boundary film and the particle. The key concept of this method is an addition theorem of film-diffusion kinetic resistance and the particle-diffusion kinetic resistance. While in hydrophilic polymers, the thickness of boundary film decreases due to the attractive force between the ion and the surface, in hydrophobic polymers, it increases with the amount of hydrophobic components. This is confirmed by using chitosan resins with hydrophilic/hydrophobic components. The experiments are based on the batch method, and degree of film-diffusion control and particle-diffusion control is determined simultaneously. The film mass-transfer coefficient in the boundary film is also determined from a simple plotting of the experimental data. This method is also applicable to ion-exchange kinetics by summing the kinetic resistances at each step in the ion-exchange reaction and the mutual diffusion. Our method will serve as a guiding tool for designing of adsorption agents and ion-exchangers. Copyright © VBRI Press.
Rohit Kandulna; Ram B. Choudhary; Rajinder Singh
Abstract
PPY, PANI and PPY-PANI-ZnO ternary nanocomposites were synthesized in the laboratory via chemical oxidative polymerization method. The formation of PPY, PANI and corresponding change in the nanostructure with the incorporation of ZnO was examined by X-ray diffraction technique (XRD). Nano-flakes like ...
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PPY, PANI and PPY-PANI-ZnO ternary nanocomposites were synthesized in the laboratory via chemical oxidative polymerization method. The formation of PPY, PANI and corresponding change in the nanostructure with the incorporation of ZnO was examined by X-ray diffraction technique (XRD). Nano-flakes like structure were formed in the PPY-PANI polymeric matrix with the embodiment of ZnO nanoparticles, as examined by surface topology images. Optical transmittance spectra showed the optimized reduced band gap ~2.67eV. Increased rate of electron-hole nonradiative recombination associated to blue and green bands was confirmed from PL spectra. An enhanced current density ~197.75% was examined due to the significantly improved conductivity of PPY-PANI-ZnO ternary nanocomposites. This improved conductivity, reduced band gap and high electron-hole recombination rate confirmed that it can be used as electron transport layer in the OLED devices.
Avanish K. Srivastava; Bhumika Samaria; Smita Soni; Virendra S Chauhan; Jitendra Singh; Rajesh K Shukla; Anuj Shukla; Narendra Kumar
Abstract
In the ongoing search for newer materials for microwave absorption applications, the graphene merits a special consideration owing to its outstanding mechanical, thermal and electrical properties. Here, we report investigation on microwave absorption properties of Fe-Co oxide- thermally exfoliated graphene ...
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In the ongoing search for newer materials for microwave absorption applications, the graphene merits a special consideration owing to its outstanding mechanical, thermal and electrical properties. Here, we report investigation on microwave absorption properties of Fe-Co oxide- thermally exfoliated graphene oxide (Fe-Co oxide-TEGO) composite in a frequency range of 8-18 GHz. Fe-Co oxide was synthesized by thermal decomposition of Fe-Co oxide/aniline- formaldehyde copolymer at 900 0C in air. Fe-Co oxide-TEGO hybrid was prepared by physical mixing of Fe-Co oxide and TEGO. Thereafter, hybrid was characterized using scanning electron microscope, energy dispersive X-ray, Fourier transform infrared spectrometer and X-ray diffractrometer. Thereafter, Fe-Co oxide-TEGO composites were prepared by intermixing in different weight % in PU (polyurethane) resin and their electromagnetic and microwave absorption properties were studied. The effect of varying the weight % of Fe-Co oxide in Fe-Co oxide-TEGO composite on electromagnetic properties was also studied. The absorption bandwidth of 3.5 GHz (8.5-12.0 GHz, X-band) and 5.0 GHz (13.0-18.0 GHz, Ku -band) has been achieved using Fe-Co oxide-TEGO composite (50 wt%) with 2.2 and 1.6 mm thickness, respectively. Microwave absorption studies show Fe-Co oxide- TEGO composite as a potential candidate for microwave absorption applications. Copyright© 2018 VBRI Press.
V. Subathra Devi; B. K. Gnanavel; P. Murthi; M. Madhanagopal
Abstract
Concrete industry, the largest consumer of natural resources such as water, sand and crushing stone needs to be reoriented by adopting environmental friendly and a highly sustainable technology. Concrete with ceramic industrial waste is termed as Ceracrete. The properties of the ingredients of concrete ...
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Concrete industry, the largest consumer of natural resources such as water, sand and crushing stone needs to be reoriented by adopting environmental friendly and a highly sustainable technology. Concrete with ceramic industrial waste is termed as Ceracrete. The properties of the ingredients of concrete need comparison before replacing the fine aggregate (FA) and coarse aggregate (CA) by ceramic waste. River sand is used as fine aggregate and broken stone as coarse aggregate. Then the concrete mix is designed as per the IS code provision for M20 grade. Concrete cubes are cast by replacing FA and CA by ceramic waste from 0% to 50% in steps of 10% as type 1(FA replacement), type 2 (CA replacement) and type 3 (FA and CA replacement). The compressive strength and workability of three types of concrete are compared with those of the conventional concrete (0% replacement). Fine aggregate replacement by ceramic waste (type 1) shows better compressive strength than type 2, type 3 and conventional concrete. But the water absorption of type 1 concrete is higher, compared to the other types. The workability of the type 1 concrete is smaller. The optimum percentage of replacement of type 1 concrete is found by design of experiments using the Taguchi method. Concrete with good workability and higher compressive strength is observed for 6.62 % to 13.97 % of replacement of fine aggregate by ceramic waste, whereas, the water absorption for this optimum percentage of replacement is similar to that of the conventional concrete. Hence ceramic waste is used as a replacement material for fine aggregate in the field of construction after analyzing the structural properties, durability, bond strength etc., The analysis shows the higher contribution of the percentage of replacement to the improvement of workability and compressive strength. Copyright © 2017 VBRI Press.
S. Harinee; K. Muthukumar; A. Abirami; K. Amrutha; K. Dhivyaprasath; M. Ashok
Abstract
Biocompatible silver (Ag) nanoparticles (NPs) were demonstrated using silver nitrate (AgNO3) and egg white extracted (EWE). Egg white mediated AgNPs were characterized and study its antimicrobial activity against human pathogenic bacteria (HPB), and under UV-light irradiation, photocatalytic degradation ...
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Biocompatible silver (Ag) nanoparticles (NPs) were demonstrated using silver nitrate (AgNO3) and egg white extracted (EWE). Egg white mediated AgNPs were characterized and study its antimicrobial activity against human pathogenic bacteria (HPB), and under UV-light irradiation, photocatalytic degradation of methylene blue (MB) has been studied. Results showed that EWE-AgNPs act as remarkable antimicrobial agent against several Gram- Positive and Negative HPB strains. Maximal growth inhibition zone in Salmonella typhimurium (NCIM 2501) and a minimal inhibition zone in Bacillus subtilis (NCIM 2920) were observed at concentration of 80μg mL-1. High activity of photocatalytic degradation of methylene blue (MB) at about 94.67% was observed under UV-light irradiation when the reaction time was extended 30 min. The multi-functionality of EWE-AgNPs may be useful for many industrial applications such as catalysis to waste water treatment in near future. Copyright © VBRI Press.
C. Rajinikanth; S. Abraham Lincon
Abstract
The unsupervised learning method is one of the formidable operations in Hyper-Spectral Image (HSI) processing. Fuzzy C-Means (FCM) clustering is an optimistic and strategic method for selecting the unsupervised bands. There are some limits and standards in fuzzy clustering technique. The Glowworm Swarm ...
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The unsupervised learning method is one of the formidable operations in Hyper-Spectral Image (HSI) processing. Fuzzy C-Means (FCM) clustering is an optimistic and strategic method for selecting the unsupervised bands. There are some limits and standards in fuzzy clustering technique. The Glowworm Swarm Optimization (GSO) is proposed with combining fuzzy clustering and GSO. The GSO is introduced to enhance the performance of fuzzy clustering to optimize the characteristics of hyperspectral images. The main objective of the proposed method is to improve the accuracy of the hyperspectral datasets and to achieve it through better computational time. The experimental results are achieved through MATLAB toolbox and the proposed method has the capability to perform with the high quality hyperspectral image classification. Copyright © VBRI Press.
Ramoshweu S. Lebelo
Abstract
In this article, an investigation into the impact of radiative heat loss in a stockpile of combustible material is considered. The heat loss is due to exothermic chemical reaction when carbon containing material of the stockpile reacts automatically with oxygen trapped within the system. The study is ...
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In this article, an investigation into the impact of radiative heat loss in a stockpile of combustible material is considered. The heat loss is due to exothermic chemical reaction when carbon containing material of the stockpile reacts automatically with oxygen trapped within the system. The study is modelled in a rectangular slab of thermal conductivity that varies with temperature and loses heat to the surrounding environment by radiation. The differential equations governing the problem are solved numerically using Runge-Kutta-Fehlberg (RKF) method coupled with shooting technique. The behaviour of each embedded kinetic parameter of the system due to variation with temperature, oxygen depletion (O2) and carbon dioxide emission (CO2), is analysed and results are graphically expressed and discussed appropriately. The results show that kinetic parameters which enhance exothermic chemical reaction correspondingly increase the temperature and CO2 emission of the combustion process. Copyright © 2018 VBRI Press.
Basu M. Daas; Debalina Das; Susanta Ghosh
Abstract
Present study reports electro-oxidation of ethanol over platinum loaded, reduced graphene oxide – ZSM-5 composite (GO-ZSM) on graphite foil (GF). To prepare the Pt/r(GO-ZSM)/GF electrode, GO-ZSM-5 composite was prepared by simple 1:1 mechanical mixing which was coated over graphite foil and electrochemically ...
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Present study reports electro-oxidation of ethanol over platinum loaded, reduced graphene oxide – ZSM-5 composite (GO-ZSM) on graphite foil (GF). To prepare the Pt/r(GO-ZSM)/GF electrode, GO-ZSM-5 composite was prepared by simple 1:1 mechanical mixing which was coated over graphite foil and electrochemically reduced at a current density of (-)1 mA.cm-2. The electro-chemical studies, such as cyclic voltammetry and chronoamperometry established that Pt/r(GO-ZSM-5)/GF electrode exhibited better tolerance towards CO-poisoning compared to Pt/rGO/GF electrode. The larger IF:IB value for Pt/r(GO-ZSM)/GF indicated much lesser carbonaceous accumulation on the zeolite modified electrode. The peak current density was comparable for both Pt/r(GO-ZSM-5)/GF and Pt/rGO/GF electrodes. Thus ZSM-5 was instrumental in reducing the catalyst poisoning without compromising with the current density. The findings of the investigation can prove useful in the search of solution for the problem of catalyst poisoning associated with platinum electrodes.
S. C. S. P. Kumar Krovvidi; G. Padmakumar; A. K. Bhaduri
Abstract
Bellows find wide applications in reactor systems such as in bellows sealed valves as primary leak tight barriers and in piping systems to absorb differential thermal expansions. Reliable operation of bellows is strongly dependent of proper material selection. Various candidates for material of the bellows ...
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Bellows find wide applications in reactor systems such as in bellows sealed valves as primary leak tight barriers and in piping systems to absorb differential thermal expansions. Reliable operation of bellows is strongly dependent of proper material selection. Various candidates for material of the bellows are austenitic stainless steels (such as SS316, SS304, SS316Ti, SS304L etc.), precipitation hardened stainless steels (such as AM350) and Nickel base alloys such as Inconel-718 and Inconel-625. This paper presents the review of the operating experience, mechanical & neutronic properties of various materials for bellows in nuclear industry. In this work, it is observed that Inconel alloys have superior mechanical properties than austenitic stainless steels but exhibit neutron embrittlement. Hence, use of Inconel bellows is limited to low neutron fluence applications. Precipitation hardened steels such as AM350 have high mechanical strength but lesser ductility. Though AM350 is not suitable for formed bellows, it has excellent operating experience for welded disc bellows in nuclear applications. Austenitic stainless steels have large operating experience. Variants of SS316 are used for high temperature and variants of SS304 are used for temperatures below creep range. ‘L’ grades or stabilized grades are used for resistance to sensitization during welding. Based on the present review work, guidelines for selection of material for bellows are drawn, satisfying the selection criterion. Copyright © 2017 VBRI Press.
Mrinmoy Garai; Basudeb Karmakar
Abstract
This study exemplifies the effects of 5 wt.% Pb2+ addition replacing the same Zn2+ content on crystallization and microstructure of 10B2O3-16Al2O3-39SiO2-12MgO-12MgF2-4K2O-1Li2O-1AlPO4 (wt.%) glass-ceramic composite. Increase of linear thermal-expansion (6.93 to 7.18×10-6/K at 50-600°C) in ...
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This study exemplifies the effects of 5 wt.% Pb2+ addition replacing the same Zn2+ content on crystallization and microstructure of 10B2O3-16Al2O3-39SiO2-12MgO-12MgF2-4K2O-1Li2O-1AlPO4 (wt.%) glass-ceramic composite. Increase of linear thermal-expansion (6.93 to 7.18×10-6/K at 50-600°C) in substituting Zn2+ by Pb2+ is attributed to the field-strength of cations. Opaque crystalline glass-ceramics are derived from the transparent glasses (synthesized by single-step melt-quenching at 1500OC) by controlled heat-treatment at 1050°C and the predominant crystalline-phase was identified as fluorophlogopite mica, KMg3AlSi3O10F2. FFESEM of the ZnO containing glass-ceramics revealed that 100-200 µm sized plate-like crystals are in ‘well-packed interlocked arrangement’; which changed to ‘nanocrystalline microstructure’ combined of ‘spherical droplet like’ nanocrystals (crystal size = 10-50 nm) in attendance of PbO. Decrease in linear thermal-expansion (11.03 to 7.93 × 10-6/K at 50-700°C) due to the substitution of ZnO is ascribed to the crystallization inhibiting tendency of PbO towards boroaluminosilicate system. Thermal-expansion of ZnO containing glass-ceramic is large (> 11 × 10-6/K at 50-700 and 50-800°C) which can exhibit their enough thermal shock resistivity to be suitable for high-temperature sealing application. Copyright © 2017 VBRI Press.
Anandraj J; Girish M. Joshi; Mayank Pandey
Abstract
We have demonstrated the successful preparation of polyvinyl alcohol (PVA) composed CuBi2S3 polyionic (PI) composites. Polymer composites were sensitive to the external stimuli, the modified PVA moiety exhibits excellent electrical property as a function of temperature. The volume resistance measured ...
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We have demonstrated the successful preparation of polyvinyl alcohol (PVA) composed CuBi2S3 polyionic (PI) composites. Polymer composites were sensitive to the external stimuli, the modified PVA moiety exhibits excellent electrical property as a function of temperature. The volume resistance measured by impedance analyzer (40 to 150oC) under broadband frequency (50Hz -1MHz). The negative temperature coefficient (NTC) was observed in the temperature range of 40 to 150oC. It offers the nonlinear resistivity, ρ = 105 (Ω-m) across pure PVA moiety. The influence of polycationic-ions crucial to obtain the gradual decrease of resistivity (ρ) up to 104 (Ω-m). The thermistor characteristics were disclosed as function of polyionic loading (wt %). Copyright © 2017 VBRI Press
Manmath Kumar Dash; T. Karthikeyan; S. Saroja
Abstract
Chromium alloyed Ferritic/Martensitic steels are widely used as structural materials in power plants, and considered for core applications of fast and fusion reactors. Characterization and fundamental interpretation of deformed microstructure through crystal plasticity principles are useful for tailoring ...
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Chromium alloyed Ferritic/Martensitic steels are widely used as structural materials in power plants, and considered for core applications of fast and fusion reactors. Characterization and fundamental interpretation of deformed microstructure through crystal plasticity principles are useful for tailoring desired microstructure by optimal processing methods. This study reports the characterization of plastic strain distribution in cold rolled 9Cr-1Mo steel using Electron back scatter diffraction (EBSD) technique. Small orientation changes within the individual grains were studied to gauge the accumulation of ‘geometrically necessary’ dislocations in deformed material, and correlate with the load geometry. The correlated misorientation angle distribution showed a significant presence of low angle boundaries in the deformed microstructure as compared to the annealed specimen. Crystal orientation map of deformation bands indicated significant intra-grain rotation, and the extent of rotation was distinctly different for different grains. A heterogeneous accumulation of plastic strain distribution is inferred from the grain maps of local misorientation angle (0.5º-5º) and orientation spread parameters. Analysis by Schmid factor criteria (0.4-0.5) showed more than 50% of the grains to exhibit favorable orientation for {110} <111> slip activity, whereas higher stress would be required for plastic deformation of remaining grains. Copyright © 2017 VBRI Press.
Mohammad Danish; Ashutosh Pandey
Abstract
Reactions of niobium (V) ethoxide (1) with 2,4-pentanedione derivatives [3-Chloro-2,4-pentanedione, 1,1,1-Trifluoro-2, 4 pentanedione, 3,3-Dimethyl-2,4-pentanedione,] afforded heteroleptic niobium alkoxide complexes [Nb(OEt)4 (CH3COCHClCOCH3)](2), [Nb(OEt)4(CF3COCH2COCH3)] (3) and [Nb(OEt)4(CH3COC(CH3)2COCH3)] ...
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Reactions of niobium (V) ethoxide (1) with 2,4-pentanedione derivatives [3-Chloro-2,4-pentanedione, 1,1,1-Trifluoro-2, 4 pentanedione, 3,3-Dimethyl-2,4-pentanedione,] afforded heteroleptic niobium alkoxide complexes [Nb(OEt)4 (CH3COCHClCOCH3)](2), [Nb(OEt)4(CF3COCH2COCH3)] (3) and [Nb(OEt)4(CH3COC(CH3)2COCH3)] (4). Two sets of Nb2O5 sculptured thin films (STFs) were deposited on ITO coated glass substrates by spin casting the gels obtained by sol gel processing of the synthesized complexes (2-4). One set of the films (Na, Nb and Nc) were calcined under ammonia gas flow and the other (a, b and c) under oxygen gas flow respectively at 500°C for 1h. A film (d) was also fabricated from niobium (V) ethoxide and calcined under oxygen gas flow at 500°C for 1h for comparisons with regard to structure, topography, optical and photocatalytic properties of Nb2O5. Crystal structure, topography, optical and photocatalytic properties of the films were determined by X-ray diffraction, atomic force microscopy, ellipsometry and UV-Vis spectroscopy. Significant band gap narrowing i.e. from 3.48 eV (d) to 2.73 eV (Nc) was observed for the films calcined under ammonia gas flux. Investigation of photodegradation of methylene blue (MB) by niobia films under UV irradiation demonstrated enhanced degradation efficiency of methylene blue dye. Copyright © 2018 VBRI Press.
S. M. Sathiya; G. S. Okram; M. A. Jothi Rajan
Abstract
Microwave assisted co-precipitation method is used to synthesize copper oxide nanoparticles from various concentrations of CuCl2.2H2O (0.1 M - 0.5 M) precursors. Both CuO and Cu2O phases are observed from X-ray diffraction (XRD) pattern and further confirmed from Energy Dispersive X-ray Analysis (EDX) ...
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Microwave assisted co-precipitation method is used to synthesize copper oxide nanoparticles from various concentrations of CuCl2.2H2O (0.1 M - 0.5 M) precursors. Both CuO and Cu2O phases are observed from X-ray diffraction (XRD) pattern and further confirmed from Energy Dispersive X-ray Analysis (EDX) and selected area electron diffraction (SAED) data. The particle size of 43 to 27 nm determined from XRD data using Scherrer formula is in good relation with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images. The existence of reasonably uniform size and shape is clear from SEM. The band gaps determined from the UV-Visible absorption peaks and vibrational modes observed from Micro-Raman Scattering (MRS) analysis further confirm the presence of CuO and Cu2O phases. These results are also related to electrical conductivity at low temperatures which illustrate different types of conduction mechanisms. The samples show semiconducting behavior with improved electrical conductivity. Finally, the material is proposed to have applications in designing gas sensors and also in regulating electrical conductivity in drug delivery systems. Copyright © 2017 VBRI Press.
