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| 1 |
ID:
148711
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| Summary/Abstract |
High emissivity coating was developed on Ni-based super alloy substrates by dip coating and spray coating technique using a chemical precursor sol. The coating material was characterised thoroughly by XRD, SEM, TEM and XPS analyses. Characterisation results showed the presence of nano carbon in the AlPO4 matrix which imparted high emissivity to the coating. Emissivity of the coating varied from 0.6 to 0.9 in the wave length range : 2 µm - 25 µm depending on the thickness of the multilayered coating. Spray coating was very effective for coating the bigger substrates and TPS panels. Emissivity offered by the spray coated substrates was little lower compared to the dip coated substrates. Emissivity offered by the spray coated substrates was little lower compared to the dip coated substrates. Cyclic oxidation performances of the coated substrates at 800 °C and 1000 °C for 100 hrs of thermal exposure were recorded and compared with that of the bare substrate. The emissivity coating was found to offer substantial oxidation resistance to the base substrate at high temperatures.
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| 2 |
ID:
148699
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| Summary/Abstract |
Materials play an important role in the fast breeder reactors. Materials used in cladding tube and fuel pins should have better creep and void swelling resistance. To overcome these difficulties, a new class of material known as oxide dispersion strengthened (ODS) steels are used. There are two groups of ODS steels, the ferritic and the austenitic ODS steels based on the matrix. The present paper reviews the current status of research in austenitic ODS steels. The interaction of dislocations with finely dispersed incoherent, hard particles that governs the strength and high temperature properties of ODS materials is briefly reviewed. The synthesis route adopted for these ODS steels, which is mostly through powder metallurgy route is also discussed. The role of various oxides such as Y2O3, ZrO2and TiO2and the clusters formed in these ODS steels on the mechanical properties and void swelling characteristics is also discussed.
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| 3 |
ID:
148712
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| Summary/Abstract |
Azadirachta indica extract has been explored as an antibiotic in hygienic chitosan matrix system to enhance antimicrobial and medicinal property in a cost effective manner. The hygienic composite system has been successfully fabricated via solvent casting. The antibacterial activities of the hybrid system were examined by agar diffusion method against gram positive S.aureus and gram negative K. pneumoniae. From conventional antibacterial test for 24 h, the system exhibited an excellent antimicrobial activity against both bacterial strains in ranges of 1.2 cm - 1.5 cm for S. aureus and 1.8 cm - 2.3 cm for K. pneumoniae Fourier transform infrared spectroscopy revealed successfully embedded A. indica on the chitosan substrate via weak electrostatic interaction, resulting in the easy release of the additive. Moreover, atomic force microscopy showed a membrane roughness of 0.084 nm which confirms the uniform distribution of the additive throughout the membrane. These hybrid membranes have potential applications in skin tissue engineering, wound healing and as coatings for implantable scaffold material.
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| 4 |
ID:
148698
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| Summary/Abstract |
Recently electro-kinetics, namely AC electro-osmosis and dielectrophoresis have been judiciously utilised to manipulate movement of polarizable particles like DNA suspended in aqueous solution and placed between electrically fed microelectrodes. Researchers around the globe have tried to fabricate electrodes of different geometries to understand how electric field owing to sharpness of the electrodes has influenced the aforementioned electro-kinetic properties. In this review, we have presented a chronological development indesign of patterned electrodes used to align and trap DNA molecules in and around the electrodes. We have examined the pros and the cons of such geometry of the set of the micro-electrodes and also tried to provide a solution in terms of shape and sharpness of the electrode that would facilitate DNA molecules to bridge between the electrodes for further application of conducting DNA as molecular wire.
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| 5 |
ID:
148705
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| Summary/Abstract |
An intelligent semi-active anti-vibration mount using a magnetorheological (MR) fluid is designed and developed for onboard applications. The mount consists of a load bearing elastomer, MR fluid chamber; MEMS based vibration sensor and a controller for closed loop feedback mechanism. The controller regulates the solenoid current in the MR fluid chamber, which in turn regulates the flow of MR fluid through the valve. Comparison of the performance of MR mount with a passive resilient rubber mount shows that the former provides 7 dB extra damping at resonance compared to the later and the isolation of MR mount starts at 10 Hz compared to 50 Hz by rubber mount. This mount can operate in real time, passive and active modes by using a closed loop feedback control mechanism. The efficacy of the mount for outdoor applications is evaluated by characterizing the mechanical, environmental, electrical and electromagnetic properties as per MIL-17185, JSS-55555 and IEC 61000 standards and found to be superior compared to passive mounts. The mount is being evaluated for onboard applications in INS Ranvijay.
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| 6 |
ID:
148704
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| Summary/Abstract |
The effect of varying Ag+ ion concentration on the green chemical reaction with a fixed tea aliquot concentration has been studied in detail with the help of UV-visible absorption spectra. With increase in the concentration of Ag+ solution the position of surface plasmon band systematically increased from 435 nm – 450 nm. The reaction followed first order kinetics and the rate of reaction increased in a linear fashion with k = 3.54 x 10-4 min-1 for 0.5 mL to k = 1.86 x 10-3 min-1 for 3.0 mL Ag+ solution. X-ray diffraction patterns showed an enhanced (200) reflection for 3.0 mL Ag sample. The shape of Ag nanoparticles could be effectively tuned from spherical to cuboid with increase in silver content as evidenced from scanning electron and transmission electron micrographs. The average particle size of Ag NPs increased from 25 nm to 55 nm with increase in the Ag+ content of the reaction.
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| 7 |
ID:
148708
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| Summary/Abstract |
The effect of Fe on the martensitic transitions, magnetic and inverse magnetocaloric effect in Ni47Mn40-xFexIn13 ribbons (x = 1, 2, 3 and 5) has been investigated. All the ribbon compositions under study have shown the presence of austenite phase at room temperature. The variation of martensitic transition with the increase in Fe-content is non-monotonic. The thermal hysteresis of the martensitic transition increased with the increase in Fe-content. The martensitic transitions shifted to lower temperatures in the presence of high magnetic fields. A maximum magnetic entropy change (∆SM) of 50 Jkg-1K-1 has been achieved in the Ni47Mn38Fe2In13 (x = 1) ribbon at 282 K for an applied field of 5 T.
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| 8 |
ID:
148703
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| Summary/Abstract |
Different compositions of (Pb1-xLax) (Zr0.60Ti0.40)O3 (abbreviated as PLZT x/60/40; x=0, 0.07, 0.08 and 0.10) ceramics were prepared by a combinatorial approach by high energy mechano-chemical ball milling and cold isostatic pressing (CIP). X-ray diffraction patterns and transmission as well as scanning electron microscope were used for the micro-structural and morphological studies. The average particle size of PLZT milled powders was measured from the TEM images and was found to be in the nm range.XRD patterns of the sintered PLZT x/60/40 ceramics confirm the perovskite phase formation after heat treatment. SEM of sintered PLZT x/60/40 ceramics show a close packed dense structure. PLZT 8/60/40 ceramics show the fine grains (~1.3 µm) with density ~97 per cent. Dielectric constant and loss were measured as a function of temperature. PLZT 8/60/40 ceramics shows the highest value of room temperature dielectric constant ~2480 at 1 kHz. Ferroelectric studies were done with the help of polarisation (P-E) and strain (S-E) vs. electric field measurements. PLZT 8/60/40 ceramics shows the maximum value of remnant polarisation (~36 µC/cm2) and strain (~0.27 per cent), respectively. PLZT x/60/40 ceramic samples were poled at optimized poling conditions. The measured values of piezoelectric charge coefficient (d33) and electromechanical coupling factor (kp) of PLZT 8/60/40 ceramics were found to be, ~690 pC/N and ~71 per cent, respectively.
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| 9 |
ID:
148707
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| Summary/Abstract |
Heusler type alloys Ni50Mn25+xGa25-x (x=2,3,4 and 5) based on near stoichiometric Ni2MnGa compositions were directionally solidified using modified Bridgman method. The alloys thus prepared were characterized for their chemical composition, crystal structure, microstructure, phase transformation, magnetic and magneto-mechanical properties. The directionally solidified Ni50Mn30Ga20 alloy rod exhibited maximum magnetocrystalline value of 95 kJm-3 and lowest detwinning stresses for martensite phase of about 5MPa. The reversible room temperature magnetic field induced strain of 0.2% under external magnetic field of 0.6T and 0.05kN bias load was obtained for the directionally solidified Ni50Mn30Ga20 alloy.
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| 10 |
ID:
148702
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| Summary/Abstract |
Synthesis by mechanochemical activation route and optimisation for power harvesting properties of nano-structured Pb0.98La0.02(NiSb)0.05[(Zr0.52Ti0.48)0.995]0.95O3 [La-PNS-PZT] ferroelectric ceramic composition has been carried out and reported here for the first time. Progressive perovskite phase formation during mechanical activation from 5 h to 40 h followed by reactive sintering was analyzed from X-Ray Diffraction analysis. Noticeable formation of perovskite phase after10 h of milling and further its completion in successive reactive sintering was observed. Particle morphology of the 10 h activated nano-La-PNS-PZT powder analysed by High Resolution Transmission Electron Microscope (HRTEM) indicated average particle size (d50) of about 24nm. Microstructural studies of samples reactively sintered at 1220 °C were performed by Field Emission Scanning Electron Microscopy (FESEM) for powders activated for various durations, indicated the compact microstructure for 10 h activation which resulted in optimum piezoelectric properties viz. piezoelectric charge coefficient (d33=449x10-12 C/N), piezoelectric voltage coefficient (g33= 32x10-3 m-V/N), Figure of merit for power harvesting (14.4 x10-12 V-m-C/N2) accompanied by excellent stability of permittivity in the range -50 °C to 100 °C. The output voltage obtained from simulated random vibrations of aerospace vehicles at various Power Spectrum Density (PSD) values, measures about 3.0 mV output across resistance of 1 kΩ indicating suitability of composition for harvesting the power from aerospace vehicle vibrations.
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| 11 |
ID:
148710
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| Summary/Abstract |
Life of any automobile engine is largely dependent on the purity as well as the optimum ratios of their fuels, viz. petrol, diesel and ethanol. A device working on the electrical metamaterial concept, namely a complementary split ring resonator (CSRR), operating at 2.47 GHz (ISM band), is proposed to detect kerosene adulteration in petrol. Kerosene was varied upto 30 per cent with minimum detection limit as low as 10 per cent. Systematic shifts in the transmission resonance frequency were observed. The sensing was fast and the recovery was instantaneous. The underlying concept of interference of electromagnetic radiation through the CSRR circuit and its further manipulation with the changes in the dielectric ambience is elaborated.
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| 12 |
ID:
148709
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| Summary/Abstract |
Low cost; easy to fabricate and flexible single wall carbon nanotubes thick film resistor (SWNT-TFR) for detailed study of NO2 detection is reported. SWNT-TFR was fabricated by vacuum filtration technique on flexible polycarbonate membrane. SWNT-TFR sensor shows selective response to NO2. The response increases from 1.47 per cent to 17.34 per cent with increasing the NO2 concentration from 0.2 ppm to 10 ppm, respectively. Different energy sources, IR, thermal and UV were explored for achieving fast recovery of the SWNT-TFR sensor. The results showed that the gas sensor gives immediate and fast recovery in the presence of UVC light. The calculated detection limit is less than 764 ppt for NO2. We are also presenting sensing of dimethyl methylphosphonate (DMMP) as a simulant of sarin. SWNT-TFR gives repeatable response of ~2.7 per cent for 500 ppm of DMMP. This work suggests the possibility to utilise SWNTs-TFR as NO2 sensors for air-quality monitoring.
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| 13 |
ID:
148701
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| Summary/Abstract |
Microstructural and compositional characterisation of electronic materials in support of the development of GaAs, GaN, and GaSb based multilayer device structures is described. Electron microscopy techniques employing nanometer and sub-nanometer scale imaging capability of structure and chemistry have been widely used to characterise various aspects of electronic and optoelectronic device structures such as InGaAs quantum dots, InGaAs pseudomorphic (pHEMT), and metamorphic (mHEMT) layers and the ohmic metallisation of GaAs and GaN high electron mobility transistors, nichrome thin film resistors, GaN heteroepitaxy on sapphire and silicon substrates, as well as InAs and GaN nanowires. They also established convergent beam electron diffraction techniques for determination of lattice distortions in III-V compound semiconductors, EBSD for crystalline misorientation studies of GaN epilayers and high-angle annular dark field techniques coupled with digital image analysis for the mapping of composition and strain in the nanometric layered structures. Also, in-situ SEM experiments were performed on ohmic metallisation of pHEMT device structures. The established electron microscopy expertise for electronic materials with demonstrated examples is presented.
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| 14 |
ID:
148697
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| Summary/Abstract |
Core-shell type magnetic nanoparticles are finding attractive applications in biomedicine, from diagnostic to cancer therapy. Both for targeted drug delivery and hyperthermia, as well as a contrast agent used for external biomedical imaging systems, small (< 20 nm) superparamagnetic nanoparticles are desired. Some iron oxide nanoparticle formulations are already approved for human administration as contrast agent for magnetic resonance imaging. However, search continues for nanoparticles with higher saturation magnetisation. Metallic, bi-metallic and intermetallic magnetic nanoparticles are finding attention. Biocompatibility and optimal clearance are important criteria for the medical applications and therefore core-shell type particles are favored, where a biocompatible shell (e.g. polymer, Silica) can prevent inadvertent host reaction with the magnetic core. A recently developed novel synthesis method (electrochemical selective phase dissolution - ESPD), which can produce core-shell magnetic nanoparticles, is reviewed in this paper. ESPD, as the name suggests, uses electro-chemical separation of a phase from metallic alloys to synthesize nanoparticles. It is a versatile method and can be adopted to produce a wide range of nanostructures in addition to the core-shell magnetic nanoparticles.
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| 15 |
ID:
148700
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| Summary/Abstract |
This review article mainly focused on the recent progress on the synthesis and characterization of emerging artificially engineered nanostructures of oxide materials as well as their potential applications. A fundamental understanding about the state-of-the-art of the synthesis for different size, shape and morphology, which can be tuned to the desired properties of oxide nanomaterials have discussed in details in this review. The present review covers the a wide range of artificially engineered oxide nanomaterials such as cadmium-, cupric-, nickel-, magnesium-, zinc-, titanium-, tin-, aluminium-, and vanadium-oxides and their useful applications in sensors, optical displays, nanofluids and defence.
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| 16 |
ID:
148706
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| Summary/Abstract |
In-situ electron microscopy is an emerging technique for real time visualisation of micro-structural changes of a specimen under some applied constraints inside microscope. In this study, in-situ nanoindentation experimentation on a carbon nanocoil inside transmission electron microscope has been reported. The elastic modulus of the carbon nanocoil is found to be 177 GPa. Similar experiments are also carried out on carbon nanotubes, but force response of carbon nanotubes is beyond the limit of sensors presently available. The present study also reports the in-situ dissolution behavior of the secondary phases of a 7xxx series aluminum alloy under high vacuum condition in scanning electron microscope (SEM) in the temperature range of 350 °C to 400 °C. We report for the first time using in-situ SEM technique that dissolution of the MgZn2-base phase present as eutectic and divorced eutectic forms could start at a temperature as low as 300 °C, although the usual homogenisation temperature of such alloys is always > 450 °C. Furthermore, the kinetics of dissolution of such phases, particularly when present in fine eutectic phase mixture, is significantly faster than what is observed under atmospheric pressure. It has been found that modification of surface composition under high vacuum condition plays a key role in the low temperature dissolution processes. It has further been found that the dissolution process does not start with the thinning of the IDC phase as proposed for Al-Zn-Mg-Cu alloys, rather it occurs by a combination of ‘spheroidisation’ and thinning process called ‘the thinning, discontinuation, and full dissolution’ (TDFD) mechanism. Results of the in-stu experiments under high vacuum are compared with the ex-situ dissolution experiments under normal atmospheric pressure.
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