C. Sarika; M.S. Shivakumar; Lakhirupa Devi; K. Rekha; B. Narasimhamurthy; Sabu Thomas; Nandakumar Kalarikkal; I. C. Lekshmi
Abstract
A comparative study of the electrochemical behaviours of two different electrode matrices used in the construction of amperometric laccase biosensors is reported here for catechol detection in water. The matrices considered are NiO nanocrystal (NC) modified graphite electrode (MCPE-NiO) and Au electrode ...
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A comparative study of the electrochemical behaviours of two different electrode matrices used in the construction of amperometric laccase biosensors is reported here for catechol detection in water. The matrices considered are NiO nanocrystal (NC) modified graphite electrode (MCPE-NiO) and Au electrode of Clark type DO sensor. The laccase enzyme from Trametes versicolour was immobilized on electrode surfaces by co-crosslinking method using bovine serum albumin, a protein-based stabilizer, along with glutaraldehyde as the crosslinking agent. A comparison of the stability parameters of the electrode designs was carried out including sensitivity, calibration plots, analytical data and storage stability, and the biosensor performance was shown to be superior for MCPE-NiO-Lac compared to Au-Lac electrode. The NC modified system reached steady state within 6 seconds after the analyte contact and displayed a lower detection limit of 0.95 μM, while the Au electrode took 3 minutes to reach the same and had lower detection limit of 4 μM. Better reproducibility and longer linear response was also observed for MCPE-NiO system compared to the latter, all of which could be attributed to the microstructure of the electrode and the surface lattice arrangement in the embedded nanocrystals. Copyright © 2018 VBRI Press.
Pawan Kumar; Amit Sanger; Arvind Kumar; Davinder Kaur; Ramesh Chandra
Abstract
In the present work, gas sensing properties of Copper (Cu) doped Zinc Oxide (ZnO) thin films have been investigated. The nanostructured ZnO and Cu doped ZnO (CZO) thin films have been synthesized using DC magnetron sputtering on glass substrates. The effect of hydrophobicity and surface roughness of ...
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In the present work, gas sensing properties of Copper (Cu) doped Zinc Oxide (ZnO) thin films have been investigated. The nanostructured ZnO and Cu doped ZnO (CZO) thin films have been synthesized using DC magnetron sputtering on glass substrates. The effect of hydrophobicity and surface roughness of the CZO thin films on the carbon monoxide (CO) gas sensing performance have been examined. Fast response time (47 sec) and an optimum recovery time (~ 86 sec) have been witnessed at an adequate temperature of 250°C for the samples having contact angle ~ 131o and surface roughness ~ 14.86 nm. Hydrophobicity of the surface provides short recovery time by opposing the existence of water-vapour on the surface. Copyright © 2018 VBRI Press.
S Sandeep; S SanthoshA; N Kumara Swamy; G S Suresh; J S Melo
Abstract
In the present work, we have biosynthesized silver nanoparticles (AgNPs) using leaf extract of Euphorbia geniculata and successfully deposited them onto the polyvinyl pyrolidone (PVP) modified graphite electrode (Gr/PVP). The resulting electrode is used as a matrix for the immobilization of glucose oxidase ...
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In the present work, we have biosynthesized silver nanoparticles (AgNPs) using leaf extract of Euphorbia geniculata and successfully deposited them onto the polyvinyl pyrolidone (PVP) modified graphite electrode (Gr/PVP). The resulting electrode is used as a matrix for the immobilization of glucose oxidase (GOx) enzyme. The immobilized electrode (Gr/PVP/AgNPs/GOx) is characterized by scanning electron microscopy and its performance is evaluated and optimized using cyclic voltammetry and differential pulsevoltammetrictechniques. Under neutral pH conditions, at room temperature, the developed Gr/PVP/AgNPs/GOx sensor showed excellent electrocatalytic activity towards the oxidation of glucose. Further, it is used for the determination of glucose in the concentration range of 0.1-7 mM with a detection limit of 0.15 µM and sensitivity of 29.72 µA mM-1 cm-2. In addition, the response of GOx biosensor is found to be uninfluenced by some common possible interferents. The findings of present work are significant and imply potential applications for biosynthesized AgNPs as effective, non-toxic biocompatible sensor fabrication materials. Copyright © 2018 VBRI Press.
Nidá M. Salem; Saba H. Alkharabsheh; Akl M. Awwad
Abstract
The present study deals with rapid and large-scale synthesis of silver nanoparticles (AgNPs) by U. tomentosa leaves aqueous extract at ambient temperature. Crystal growth of silver nanoparticles by this green route was formed within 5min at room temperature. Synthesized AgNPs were characterized by Ultra-violet ...
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The present study deals with rapid and large-scale synthesis of silver nanoparticles (AgNPs) by U. tomentosa leaves aqueous extract at ambient temperature. Crystal growth of silver nanoparticles by this green route was formed within 5min at room temperature. Synthesized AgNPs were characterized by Ultra-violet visible spectrophotometer (UV-vis), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and X-ray diffraction (XRD). Silver nanoparticles synthesized by green route showed better antibacterial activity. Copyright © 2018 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.
Himanshu Bisaria; Pragya Shandilya
Abstract
Ni-rich NiTi shape memory alloys (SMAs) are gaining more prominence compared to near equiatomic NiTi SMAs due to their excellent superelasticity and shape memory properties. The low density and high work output compared to steels make them an excellent choice for automotive and aerospace industries. ...
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Ni-rich NiTi shape memory alloys (SMAs) are gaining more prominence compared to near equiatomic NiTi SMAs due to their excellent superelasticity and shape memory properties. The low density and high work output compared to steels make them an excellent choice for automotive and aerospace industries. The study explores the effect of machining parameters, namely, pulse off time, pulse on time, spark gap voltage, wire tension and wire feed rate on material removal rate (MRR), surface roughness (Ra), and surface morphology of Ni-rich NiTi SMA. The experimental results reveal that MRR & Ra increase with the increase in pulse on time while decrease with the increase in pulse off time and spark gap voltage. Wire feed rate and wire tension have negligible influence on MRR and SR. Surface defects, namely, recast layer, micro-cracks & voids were examined through scanning electron microscope (SEM). Energy dispersive X-ray (EDS) and X-ray diffraction (XRD) analysis results reveal the material transfer from wire electrode and the dielectric fluid on the machined surface. Copyright © 2018 VBRI Press.
I.N.G. Wardana
Abstract
This study aims to utilize of bio material to produce green hydrogen energy through hybrid of the activated carbon and the CuO catalyst in vegetable oil steam reformer. The experiment was done in the atmospheric pressure steam reformer. The results show that activated carbon and CuO individually performs ...
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This study aims to utilize of bio material to produce green hydrogen energy through hybrid of the activated carbon and the CuO catalyst in vegetable oil steam reformer. The experiment was done in the atmospheric pressure steam reformer. The results show that activated carbon and CuO individually performs the same trend in producing hydrogen. Their combination accelerates hydrogen production. This indicates that heat energy makes CuO alters the electron density around the reactant by combining the van der Waals force with the induction due to electron jump in its narrow ban gap. Therefore, CuO activate effectively the polar water (H2O) molecules. More energy is needed to alter the electron in stable large molecule triglyceride of vegetable oil. On the other hand, the activated carbon does it by combining the van der Waals force with the induction due to delocalized of the pi electrons travelling between carbon atoms in the graphite structure. Consequently, only the nonpolar triglyceride molecules are attracted while the polar H2O are repelled by hydrophobic force. Thus, larger energy is needed to activate electrons in H2O. When they are combined, the CuO works only on H2O while activated carbon does only on triglyceride which is highly effective. Copyright © 2018 VBRI Press.
Elena Brandaleze; Mykhaylo Romanyuk; Martina Avalos
Abstract
The alloy design concepts of high performance steels, involve the knowledge on the stability of carbides associated with nanoscale phenomena present in the structure as result of the deformation suffered during the thermomechanical processes. The understanding of the nanoscale phenomena open new frontiers ...
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The alloy design concepts of high performance steels, involve the knowledge on the stability of carbides associated with nanoscale phenomena present in the structure as result of the deformation suffered during the thermomechanical processes. The understanding of the nanoscale phenomena open new frontiers to understand mechanical behaviours in the steel, not totally clarified until now. The paper discuss the structure evolution during wire drawing of pearlitic steels and the impact of cementite stability on different nanoscale structure phenomena, which explain the specific mechanical behaviour to achieve ultra-high strength. Results on the kinetic and stability of carbides predicted on the base of thermodynamic simulation are correlated with thermal analysis tests results (dilatometry and differential scanning calorimetry) carried out by different authors in order to understand the cementite (Fe3C) dissolution during plastic deformation. In addition, information obtained by traditional and no traditional microscopy techniques and X ray diffraction complete the study and allows to understand more deeply the structure evolution, including nanoscale phenomena that justify the mechanical behaviour during wiredrawing and the final strength level. The dislocation substructure evolution together with the cementite dissolution during sever plastic deformation which leads to a steadily increase of the strain hardening is clarified. Copyright © 2018 VBRI Press.
Sarajit Biswas
Abstract
First principles electronic structure calculations implemented in the density functional theory have been employed to investigate the electronic and magnetic properties of VO2 in the high temperature rutile structure with tetragonal P42/mnm symmetry. The system is a nonmagnetic metal in the absence of ...
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First principles electronic structure calculations implemented in the density functional theory have been employed to investigate the electronic and magnetic properties of VO2 in the high temperature rutile structure with tetragonal P42/mnm symmetry. The system is a nonmagnetic metal in the absence of Hubbard- type Coulomb interaction U. It is revealed in this study that the three V-t2g states are degenerate due to partial electron filling which is responsible for orbital fluctuations between them. Due to these orbital fluctuations and sharing of single 3d electron by V-t2g states, no band gap opens in the close vicinity of Fermi level. Nevertheless, upon the application of U = 4 eV, the system encounters metal to half-metal transition without any structural phase transitions exhibiting ferromagnetic behaviour. In spin up channel, dyz and dxz states remain degenerate while dx2- y2 state is more occupied but are strongly hybridized with O-2p orbitals resulting ferromagnetism. In spin down channel, Fermi level is suppressed below the V-t2g bands while V- 4s state is shifted above the Fermi level causing opening of a band gap near the Fermi level. Copyright © 2018 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.
Toshiyuki Sameshima; Yoshihiro Ogawa; Masahiko Hasumi
Abstract
Reduction of optical reflection loss at the intermediate region is discussed in three mechanical stacked samples: top Si and bottom Ge substrates, top GaAs and bottom Si substrates, and top GaP and bottom Si substrates using an epoxy-type adhesive with a reflective index of 1.47. Transparent conductive ...
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Reduction of optical reflection loss at the intermediate region is discussed in three mechanical stacked samples: top Si and bottom Ge substrates, top GaAs and bottom Si substrates, and top GaP and bottom Si substrates using an epoxy-type adhesive with a reflective index of 1.47. Transparent conductive Indium gallium zinc oxide (IGZO) layers with a refractive index of 1.85 were used as antireflection layers. IGZO layers were formed on the bottom surface of the top substrate and the top surface of the bottom substrate of the three stacked samples with thicknesses of 188, 130, and 102 nm. The IGZO layers well decreased the optical reflectivity of the stacked samples. The IGZO layers provided high effective optical absorbency Aeff of bottom substrates of 0.925, 0.943, and 0.931, respectively, for light wavelength regions for light in which the top substrates were transparent and the bottom substrates were opaque. High Aeff maintained for the light incident angle between 0 to 50o. Copyright © 2018 VBRI Press.
Research Article
Paula Louro; Manuela Vieira; Manuel A. Vieira; J. Costa
Abstract
We propose the use of Visible Light Communication (VLC) for localization services and navigations. The proposed lighting system supplies the dual function of lighting and data transmission. It uses commercial RGB white LEDs for the generation of the light and of the modulated optical signals that are ...
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We propose the use of Visible Light Communication (VLC) for localization services and navigations. The proposed lighting system supplies the dual function of lighting and data transmission. It uses commercial RGB white LEDs for the generation of the light and of the modulated optical signals that are transmitted in free space using an on-off coding scheme. The red, green and blue emitters of white LEDs are independently modulated, transmitting each different information. The photodetector is a multilayered device based on a-SiC:H, designed for the detection of visible optical light. The generated electrical signal by the photodetector is strictly related to the input optical excitation and its demodulation and decode enables the identification of the input light signals that carry the information necessary to perform the positioning and navigation tasks. The photodetector works as an active optical filter presenting self-amplification at selectable wavelengths. It is a multilayered device composed by two stacked pin photodiodes fabricated between conductive transparent electrical contacts. The positioning system includes multiple, identical navigation cells. The decoded signal by the photodetector identifies the input emitter cell and supplies enhanced accuracy within the spatial region covered by the cell. The methodology used for the photocurrent signal processing involves Fourier transform analysis for frequency identification and the use of a photodetector with spectral selective properties of wavelength identification. An algorithm to decode the information is established and the positioning accuracy is discussed. The experimental results, confirmed that the proposed VLC architecture is suitable for the intended application. Copyright © 2018 VBRI Press.
