Review Article
Rachna .; Baljeet S. Saharan; Mahender S. Yadav; Nisha Sharma; Brijesh Prasad; P P Bhingole
Abstract
Magnesium is proving itself as a new generation metallic biomaterial which has the natural ability to biodegrade itself due to corrosion when made to interact with human tissues along with aqueous body fluid to treat, improve or replace anatomical elements of the human body. Magnesium based implants ...
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Magnesium is proving itself as a new generation metallic biomaterial which has the natural ability to biodegrade itself due to corrosion when made to interact with human tissues along with aqueous body fluid to treat, improve or replace anatomical elements of the human body. Magnesium based implants serves as temporary scaffold when they are placed in vivo and vitro which acts as temporary support for the part to be healed and was found that the healing took at a faster rate. After a deep search studying and observing different study work it was found that these implants were physiologically compatible, nontoxic, cytocompatible and stimulates bone growth with other favorable characteristics. Magnesium based alloys are very much helpful in different structural body parts such as orthopedic, dentistry, cardiovascular, craniofacial, otorhinology. Main concentration of this review was to discuss some of the more commonly available and frequently used methods for development of bio implant materials and their strengthening mechanism. This review work puts a light on the summary of magnesium based material development for different biomedical applications, with their biocorrosion behavior with advantages, weaknesses and characteristics, as well as a biological translation for these results. This will help the new researchers, scientists, scholars to find a better light material as bioimplant which are in them biodegradable and reduces the pain of secondary surgery. Copyright © 2018 VBRI Press.
Research Article
Halina Grushevskaya; George Krylov
Abstract
Earlier proposed theoretical approach to the band theory of two-dimensional (2D) semimetals based on a self-consistent Dirac–Hartree–Fock field approximation, a quasi-relativistic model of Dirac 2D material in the tight-binding approximation with accounting of p-electron orbitals has been ...
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Earlier proposed theoretical approach to the band theory of two-dimensional (2D) semimetals based on a self-consistent Dirac–Hartree–Fock field approximation, a quasi-relativistic model of Dirac 2D material in the tight-binding approximation with accounting of p-electron orbitals has been developed. Fermi velocity becomes an operator within this approach. The model admits a Weyl type of charge carriers described by chiral bispinors. Since Weyl fermions in a pair have equal in absolute but opposite in sign values of pseudo- helicity (topological charge), due to the topological charge conservation law Weyl fermions can decay only in pairs. Therefore, in contrast to the Dirac electrons and holes, Weyl fermions turns out to be long-lived quasiparticles. Stability of the band structure of the 2D materials is stipulated by coupling of valley currents with pseudospins of chiral Weyl charge carriers. Numerical simulation of the band structure has been performed for the atomically thin model layers (monolayers) of C and Pb atoms, taking into account only corrections up to 4th order in wave vector. Such features of the band structure of 2D semimetals as appearance of three pairs of Weyl-like nodes; partial removal of Dirac cone and replicas degeneration are shown to be naturally explained within the developed formalism. Since the Dirac cone replica is split into oppositely directed cones, the monolayers of atoms C and Pb are 2D materials, in which pairs of Weyl massless fermions can be excited. Simulation of charge transport in these materials has been performed. Copyright © 2018 VBRI Press.
Research Article
E. Murugan; K Kalpana
Abstract
Graphene functionalized with Poly(amidoamine) dendrimer stabilized PdNPs (r-GO-PAMAM-Pd) composite was prepared through facile experimental routes and characterized by FT-IR, XRD, Raman, SEM and EDAX techniques. Initially, poly(amidoamine) generation 3 (PAMAM (G3)) dendrimer was functionalized on graphene ...
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Graphene functionalized with Poly(amidoamine) dendrimer stabilized PdNPs (r-GO-PAMAM-Pd) composite was prepared through facile experimental routes and characterized by FT-IR, XRD, Raman, SEM and EDAX techniques. Initially, poly(amidoamine) generation 3 (PAMAM (G3)) dendrimer was functionalized on graphene oxide (GO) and the resulting matrix was loaded with PdNPs through stabilization and thus produced excellent conducting composite material. The electro-catalytic activity of this composite was inspected by coating on bare GCE and thus produced stable and efficient GC-r-GO-PAMAM (G3)-Pd electrode and this in turn demonstrated for the oxidation of formic acid (FA). The occurrence of the oxidation reaction was monitored by cyclic voltammetric (CV) and linear sweep voltammetric (LSV) techniques in 0.5 M H2SO4 medium at the potential window of -0.3 to 1.0 V vs. Ag/AgCl, v = 50 mVs-1. The observed peak potential for the new electrode was located at 0.15V and compared with existing electrodes derived from different GO/Pd composites.The comparative results reveals that the newly designed electrode shown an excellent catalytic activity, more resistant to the surface poisoning and the anodic onset potential was more negative than the reported electrodes. This improved electro-catalytic performance are due to the contribution of synergetic effect of GO, dendrimer and PdNPs. Copyright © 2018 VBRI Press.
Research Article
S. Pranav; Shifna Ashraf; P. Shanmugam; V.M. Sivakumar; K. Kannan
Abstract
Cage type catalysts, especially zeolites are very significant in hydrocarbon processing reactions like cracking, isomerization, alkylation, etc. These catalysts when obtained using synthetic sources make the synthesis non-economical. Naturally available clays can serve as a host for the synthesis of ...
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Cage type catalysts, especially zeolites are very significant in hydrocarbon processing reactions like cracking, isomerization, alkylation, etc. These catalysts when obtained using synthetic sources make the synthesis non-economical. Naturally available clays can serve as a host for the synthesis of such catalysts. Kaolin, as the silica and alumina source, is particularly suitable for the preparation of zeolites due to the high quality and low price. The organic templates are usually used to vary the crystal size and impregnate acid sites on the catalyst. N-propyl amine has been chosen as the template for the synthesis processes. Hydrothermal and ultrasonic methods were performed to determine the effectiveness of each. Hydrothermal synthesis was carried out in a Teflon lined hydrothermal reactor at 100˚C for various time intervals. Ultrasonic synthesis was carried out in a bath type ultrasonicator at 30 KHz at 40˚C for time spans. The morphology of the obtained catalysts was studied by SEM and XRD analyses. The acid sites concentrations of the catalysts were studied by pyridine adsorbed FTIR analysis and the results were compared. Copyright© 2018 VBRI Press.
Research Article
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.
Research Article
Bhumika Samaria; Avanish K. Srivastava; Virendra S Chauhan; Jitendra Singh; Smita Soni; Manoj K Dhaka; Rajesh K Shukla; Anuj Shukla; Narendra Kumar
Abstract
The discovery of graphene and subsequent development of graphene-based nanocomposites in different matrices including that in polymer is an important addition in the area of nanoscience and technology. This work deals with the studies on the dielectric properties of the nanocomposites of graphite, graphite ...
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The discovery of graphene and subsequent development of graphene-based nanocomposites in different matrices including that in polymer is an important addition in the area of nanoscience and technology. This work deals with the studies on the dielectric properties of the nanocomposites of graphite, graphite oxide (GO) and thermally exfoliated graphene oxide (TEGO) in epoxy matrix. GO was synthesized using modified Hummers method which on heat treatment at ~300 0C resulted into formation of graphene oxide termed as TEGO. The synthesized GO and TEGO were characterized using scanning electron microscope, energy dispersive X-ray, Fourier transform infrared spectrophotometer, Raman spectrometer, X-ray diffractometer, UV-Vis spectrometer, CHNSO analyzer, surface area analyzer, and dc electrical conductivity. Composites using graphite powder (GP), GO and TEGO individually were prepared in epoxy resin. The dielectric (dielectric permittivity, dielectric loss tangent) properties of composites were studied in frequency range of 8 - 12 GHz. Dielectric tangent loss (tande) vary from 0.02 for GP to 0.35 for TEGO. The effect of addition of GP to GO and TEGO composite on dielectric properties was investigated. The order of tandevalues of composites is: TEGO > GP-TEGO > GP-GO> GO >GP. TEGO composite showed significant dielectric loss among the reported composites. The results thus indicate TEGO as filler for epoxy based composites to afford specific dielectric properties, especially as an alternative of much more expensive carbon nanotubes. Copyright © 2018 VBRI Press.
Research Article
Nidhi Puri; Raj K. Gupta; Akhyaya K. Pattanaik; Navin C. Mehra; Ajit K. Mahapatro; Ram P. Tandon
Abstract
The present paper highlights the synthesis of cobalt antimonide (CoSb3) micro/nanostructures by following solvothermal technique with water as solvent. Recipe is optimized for preparation of refined CoSb3 compounds and demonstrated that a high processing temperature of 500 °C and long duration of ...
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The present paper highlights the synthesis of cobalt antimonide (CoSb3) micro/nanostructures by following solvothermal technique with water as solvent. Recipe is optimized for preparation of refined CoSb3 compounds and demonstrated that a high processing temperature of 500 °C and long duration of 72 hr indicates presence of CoSb3 phase. The microstructures and composition of the as synthesized CoSb3 nanocomposites are characterized to achieve the optimized phase.The morphologies as imaged using field emission scanning electron microscope resemble granules for the as-synthesized CoSb3. The phase purity and crystallographic structure of the as-synthesized CoSb3 nanocomposites as determined by XRD indicates the formation of the cubic phase of CoSb3 and agrees well with the JCPDS data mentioned for the highly pure CoSb3. The EDX estimates the elemental composition of Co and Sb in 1:3 stoichiometric ratio for the as-synthesized CoSb3. The currently prepared nanosized skutterudite CoSb3 material synthesized by solvothermal method could be utilized as active material for the development of highly efficient thermoelectric devices. Copyright © 2018 VBRI Press.
Research Article
Raj K. Gupta; Ajit K. Mahapatro; Ram P. Tandon
Abstract
This work demonstrates the achievement of high thermopower in the pellets of calcium cobalt oxide (Ca3Co4O9) co-doped with aluminium (Al) and titanium (Ti). The pellets of Ca(3-x)AlxCo(4-y)TiyO9+δ with x, y = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5, oxide ceramics are prepared using a hot-press machine ...
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This work demonstrates the achievement of high thermopower in the pellets of calcium cobalt oxide (Ca3Co4O9) co-doped with aluminium (Al) and titanium (Ti). The pellets of Ca(3-x)AlxCo(4-y)TiyO9+δ with x, y = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5, oxide ceramics are prepared using a hot-press machine by applying an uniaxial pressure of 70 MPa at a dwell temperature of850 ºC. Microstructure imaging reveals compactness of good connectivity among grains with the estimated density using Archimedes principle suggests the formation of near perfect (99%) relative density for the new pelleted ceramics. All theco-doped samples exhibit lower electrical resistivity (r) values compared to pure Ca3Co4O9. The maximum Seebeck coefficient (S) of 177 μV/K at 750 K is achieved for the pure Ca3Co4O9 sample. A significant improvement of 18% in the power factor (S2/r) is realized at 750 K in the co-doped samples containing 0.2 mol% of Al and Ti co-doping. The demonstration of significant thermoelectric properties of Ca(3-x)AlxCo(4-y)TiyO9+δ suggest that these materials could be utilized as promising active material in thermoelectrics. Copyright © 2018 VBRI Press.
Research Article
Dinesh Ramesh; Giri Prasad.M.J; Abhishek Raaj.A.S; Jerome Santharaj.N; Rishi Kumar.R; Santhip. J; Devashankar. S
Abstract
Engine oil is primarily used to carry away the excess heat from engine and to provide lubrication to moving parts of the engine, thereby reducing friction and wear between the rubbing surfaces. However with time net heat stored in the bulk of the engine oil becomes greater than its thermal conductivity ...
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Engine oil is primarily used to carry away the excess heat from engine and to provide lubrication to moving parts of the engine, thereby reducing friction and wear between the rubbing surfaces. However with time net heat stored in the bulk of the engine oil becomes greater than its thermal conductivity causing a drastic reduction in its viscosity leading to formation of oil sludges inside the engine. Previous studies prove that the nano engine oil prepared by dispersing nanoparticles into engine oil provides enhanced operational characteristics when compared to plain engine oil, but are accompanied by the high cost of preparation and low stability of the nano engine oil[1]. In the present study a nano base oil which is a dispersion of MWCNTs and ZnO nanoparticles of ratio 1:4 in mineral oil was prepared by the two step preparation process. Tribological properties such as wear resistance, friction co-efficient and thermophysical properties such as thermal conductivity, viscosity, flash point of the nano base oil were evaluated and were compared with SAE 20W40 engine oil. The results obtained reveal that nano base oil possess better tribological and thermophysical properties when compared to engine oil, which will eventually improve the lifetime of the engine components. Copyright © 2018 VBRI Press.
Research Article
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.
Research Article
. Baijnath; Pankaj Kumar Tiwari; Suddhasatwa Basu
Abstract
In the present work, different synthesis methods i.e., sol-gel method, glycine-nitrate method and solid state route have been used to synthesize lanthanum strontium cobaltite (LSCO), which is utilized as cathode in low and intermediate temperature solid oxide fuel cell (SOFC). Calcination temperature ...
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In the present work, different synthesis methods i.e., sol-gel method, glycine-nitrate method and solid state route have been used to synthesize lanthanum strontium cobaltite (LSCO), which is utilized as cathode in low and intermediate temperature solid oxide fuel cell (SOFC). Calcination temperature for LSCO has been determined by TGA. XRD, SEM, EDX and TEM have been used to assess the phase purity, crystallite size, morphology, distribution of constituent elements and particle size of synthesized LSCO material. Two-probe AC conductivity method has been used to calculate the ionic conductivity of LSCO in air environment between 400-800°C. LSCO synthesized by sol-gel method provided highest ionic conductivity of 0.42 S/cm at 700°C and lowest activation energy of 31.60 kJ/mol between 500 to 700 °C among all the methods. LSCO synthesized by sol-gel method gives lowest area specific resistance (ASR) of 3.52 Ω cm2 at 800°C for half-cell (LSCO/YDC). High ionic conductivity and low polarization resistance established LSCO synthesized by sol-gel method, as the potential cathode material. Copyright © 2018 VBRI Press.
Research Article
Anil S. Meshram; Ompraksh P. Chimankar; Yashwantrao D. Tembhurkar
Abstract
Thin films of CuInTe2(1-x)S2x were grown by spray pyrolysis and develop thin films on glass substrate at 350C by varying proportion x in the range of 0.25. Aqueous solutions of cupric chloride, indium tri-chloride, thio-urea and tellurium tetra-chloride mixed in proper composition x and studies their ...
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Thin films of CuInTe2(1-x)S2x were grown by spray pyrolysis and develop thin films on glass substrate at 350C by varying proportion x in the range of 0.25. Aqueous solutions of cupric chloride, indium tri-chloride, thio-urea and tellurium tetra-chloride mixed in proper composition x and studies their electrical properties of all these films. The resistivity of the films was measured for temperature ranging from 77 K to 473 K. The activation energies values were calculated from Arrhenius plot. At very low temperature a variable range hopping conduction mechanism appears to be operative. Surface of thin films has been studied by Scanning Electron Microscope. Copyright © 2018 VBRI Press.
