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In present research work, the prime interest is to grow highly ordered and vertically aligned titanium oxide nanotubes for potential use in the dye-sensitized solar cells. The aim is to achieve high photovoltaic conversion efficiency and... more
In present research work, the prime interest is to grow highly ordered and vertically aligned titanium oxide nanotubes for potential use in the dye-sensitized solar cells. The aim is to achieve high photovoltaic conversion efficiency and low production cost. We have investigated the formation of TiO2 naonotubes by electrochemical anodization of 25 µm thick and highly pure (99.7%) titanium foil. The electrolyte used is the ethylene glycol with varying concentration of ammonium fluoride (NH4F) and fixed concentration of deionized water. The nanotubes morphology strongly depends upon applied voltage and fluoride concentration. It is found that double anodization of sample in the same electrolyte results in more ordered structures. So far we have achieved nanotubes with 100 nm diameter and 23 µm long. Scanning electron microscopy and current vs time profile (taken by Lab view software) are used to understand the morphology and growth of tubes. X-Ray diffraction and UV- visible spectrosc...
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Face centered cubic (FCC) high-entropy alloys (HEA) exhibit excellent ductility while body centered cubic (BCC) HEAs are characterized by high strength. Development of fine two-phase eutectic microstructure (consisting of a tough phase... more
Face centered cubic (FCC) high-entropy alloys (HEA) exhibit excellent ductility while body centered cubic (BCC) HEAs are characterized by high strength. Development of fine two-phase eutectic microstructure (consisting of a tough phase such as fcc and a hard phase such as bcc/intermetallic) can help in obtaining an extraordinary combination of strength and ductility in HEAs. Designing eutectic high entropy alloys is an extremely difficult task for which different empirical and non-empirical methods have been previously tried. In the present study, the possibility of developing a eutectic microstructure by the addition of Mo to CoCrFeNi was evaluated by calculation of the pseudo-binary phase diagram. Experimental results validated the presence of eutectic reaction in the calculated phase diagrams; however, small changes in the calculated phase diagrams were proposed. It has been shown that calculated pseudo-binary phase diagrams can provide a very good starting point for the developm...
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Abstract High entropy alloys (HEA) are an emerging class of metallic materials that have shown the potential to outsmart conventional alloy systems in terms of different physical and mechanical properties. Development of eutectic... more
Abstract High entropy alloys (HEA) are an emerging class of metallic materials that have shown the potential to outsmart conventional alloy systems in terms of different physical and mechanical properties. Development of eutectic microstructure in high entropy alloys can help in obtaining even better combination of mechanical properties due to fine distribution of phases. Eutectic high entropy alloys have been developed in the present study by addition of tantalum to the CoCrFeNi system. Pseudo binary phase diagram of CoCrFeNi–Ta was calculated with the help of Thermocalc software. Different alloy compositions were prepared by arc melting under argon atmosphere. Development of lamellar microstructure consisting of FCC and Laves phase was confirmed by the microstructural and crystal structure characterization carried out with the help of SEM and XRD. Necessary changes in the calculated phase diagram, in the light of microstructure and crystal structure characterization results, has been proposed. To evaluate the effect of eutectic microstructure on the mechanical properties of developed alloys, mechanical characterization was carried out with the help of compression tests and hardness tests. Development of eutectic microstructure consisting of FCC and Laves has helped in significantly improving the yield strength of developed alloys without causing drastic decrease in ductility. Completely eutectic alloys have shown better combination of mechanical properties in comparison to the respective hypoeutectic and hypereutectic high entropy alloys. It is believed that development of complete eutectic microstructure in high entropy alloys can help in obtaining alloys with significantly improved combination of strength and ductility.
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The interaction of mechanical components experiencing relative movements and cyclic loads in a corrosive environment is known as fretting corrosion or tribocorrosion. In the current work, the mechanism of crack initiation and propagation... more
The interaction of mechanical components experiencing relative movements and cyclic loads in a corrosive environment is known as fretting corrosion or tribocorrosion. In the current work, the mechanism of crack initiation and propagation in dovetail slots of Ti6Al4V samples (in contact with carbide rods) under fretting corrosion conditions was investigated. A newly developed test rig installed on a universal testing machine was used to conduct tests at 20 Hz frequency under 5 and 7.5 kN fretting loads. Tests were conducted at room temperature in 3.5% NaCl and phosphate-buffered saline solutions. Crack propagation in all samples was examined by a metallurgical microscope, and the detailed analysis of fractured samples was carried out by a scanning electron microscope. In comparison to dry conditions, early crack initiation and faster crack propagation were observed in salt and physiological solution environments. Colored spots and large amounts of chlorine, sodium, and oxygen were fo...
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Magneto-photonic crystals/MPCs are promising candidates for devising high-fidelity embedded biosensor system which offers facile & real time detection of diagnostic proteins. Despite of extensive use of magnetic nanomaterials for... more
Magneto-photonic crystals/MPCs are promising candidates for devising high-fidelity embedded biosensor system which offers facile & real time detection of diagnostic proteins. Despite of extensive use of magnetic nanomaterials for theranostic...
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In the present work, we have investigated the influence of temperature on the morphology of anodically produced self-organized titanium oxide nanotubes (TiNTs). TiNTs are synthesized by two-step anodization in ethylene glycol-based... more
In the present work, we have investigated the influence of temperature on the morphology of anodically produced self-organized titanium oxide nanotubes (TiNTs). TiNTs are synthesized by two-step anodization in ethylene glycol-based electrolytes containing ammonium fluoride and deionized water. Experiments are performed at constant anodization voltage of 50 V for 2 h. An investigation by the SEM images reveals that if the temperature is kept constant during the anodizing experiment, variation in the average tube diameter is significantly reduced. Degree of pore arrangement, pore size and oxide thickness increased with the increase in temperature as observed at a range of electrolyte temperatures fixed between 5°C and 40°C. However, if the temperature is not controlled during the anodization experiment, then due to the exothermic nature of the reactions to the formation of TiNTs, the temperature of the electrolyte continues to increase. This variation in electrolyte bath temperature introduces strong variations in tube diameter (10–160 nm) along the length of the tubes. Current profiles, recorded during the anodization experiments, predict the effect of constant and varying experimental temperatures as well. In both cases, XRD results show the complete anatase crystal structure of nanotubes upon annealing at 450°C. The present work highlights the importance of fixed processing temperature during the anodization experiments in order to develop an ordered array of nanotubes with a uniform tube diameter.
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Bone is a rigid and constantly remodeling organ, a type of tissue which provides support and protects organs in the body, and together they form the skeleton [1]. Materials generally used for implants bear tissue rejection and produce... more
Bone is a rigid and constantly remodeling organ, a type of tissue which provides support and protects organs in the body, and together they form the skeleton [1]. Materials generally used for implants bear tissue rejection and produce toxins on degradation [2]. Our objective is to synthesize a biocompatible composite of Hydroxyapatite (HA) and Cellulose using Cellulose Acetate as a matrix which mimics the properties of natural bone that can be used for bone replacements. Bone is composed of calcium phosphate (HA) and collagen, which gives bone desired properties [3]. Hydroxyapatite is the inorganic mineral found in the bone and is preferred due to its mechanical properties, biocompatibility, slow degradation in physiological environment and bioactivity [4]. Cellulose, structural component in plants is similar in properties to collagen therefore the properties of cellulose [4], HA and cellulose acetate are exploited to achieve our results. The experimental procedure is divided into t...
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Abstract Combined structure of anodic TiO2 nanotubes and TiO2 nanoparticles (TiNTs-TiNPs) has been synthesized by a facile combination of hydrothermal and chemical vapor deposition methods. Ordered TiO2 nanotubes with smooth walls were... more
Abstract Combined structure of anodic TiO2 nanotubes and TiO2 nanoparticles (TiNTs-TiNPs) has been synthesized by a facile combination of hydrothermal and chemical vapor deposition methods. Ordered TiO2 nanotubes with smooth walls were fabricated by two step anodization method in ethylene glycol containing NH4F at 50 V. This nanotubular array after annealing at 450 °C was subjected to the hydrothermally produced gaseous environment in an autoclave with diluted TiCl4 solution at its bottom. Vapors of TiCl4 were allowed to react chemically with water vapors for predefined time durations at 180 °C that resulted in the deposition of TiO2 nanoparticles on tubes’ surface and side walls. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that for one hour reaction duration, nanoparticles were evenly coated on the walls of nanotubes, whereas, longer durations tend to deteriorate the tubular structure. Consequently, the ordered TiNTs-TiNPs array produced after one hour coating has shown better performance for dye-sensitized solar cell DSSC) in back illumination mode with 130% increase in efficiency as compared to the device based on bare TiO2 nanotubes. The same photoanode has higher reflective properties with higher scattering ability. The solar cell based on this photoanode exhibits higher external quantum efficiency and effective charge transport properties. This study shows that porous ordered 1D structures based on TiO2 are of crucial importance for the high performance of DSSCs.
This paper reports on the self-branching of TiO2 nanotubes during anodization of Ti metal carried out at a fixed applied potential. These nanotubes are prepared by a two-step anodization carried out in an aqueous electrolyte containing... more
This paper reports on the self-branching of TiO2 nanotubes during anodization of Ti metal carried out at a fixed applied potential. These nanotubes are prepared by a two-step anodization carried out in an aqueous electrolyte containing ethylene glycol and ammonium fluoride at a range of anodization voltages of 30–60 V. The self-branching of nanotubes is more pronounced in the first-step anodization than during the second-step anodization at each voltage studied. The nanopits on the titanium surface, exposed after the dissolution of the oxide layer formed in the first-step anodization are observed to be highly regular and uniform. These nanopits provide nucleation sites producing less branched arrays during second step of anodization. Moreover, symmetric pits also result in straight tubes from top to bottom. Considering different applied voltages, the TiO2 nanotubes prepared at 50 V are comparatively more uniform and tend to grow straighter, whereas, numerous turns and pore branching are observed at other applied voltages. In this way, the best order in the tube arrays is found at anodization voltage of 50 V shown by the quantitative analysis as well. In addition, the nanotubes prepared by second-step anodization have shown higher crystallinity and with anatase as the major crystalline phase.
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Abstract We report the effect of surface plasmon modes of Au-NPs embedded in ZnO/Au/TiO2 nanoheterostructures on its optical properties. Au NPs of various sizes were coated on ZnO nanrods and then covered by a thin film of TiO2. The ZnO... more
Abstract We report the effect of surface plasmon modes of Au-NPs embedded in ZnO/Au/TiO2 nanoheterostructures on its optical properties. Au NPs of various sizes were coated on ZnO nanrods and then covered by a thin film of TiO2. The ZnO and TiO2 were synthesized in wurtzite and anatase phases, respectively. SEM and TEM images showed that ZnO nanorods were aligned; Au had spherical morphology covered by TiO2. The observed SPR mode was red shifted from 600 nm (2.06 eV) to 633 nm (1.96 eV). The PL spectra showed two bands, UV (3.1 eV) and red (1.8–2.0 eV) bands, which decreased in intensity with the increase in the strength of SPR mode. The ratio of UV to red band integrated intensities followed the SPR intensity attributed to transfer of hot carriers from Au-NPs to TiO2 layer. The present study confirmed the tuning of optical properties through plasmon resonances in nanoheterostructures.
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The present study reports ecofriendly synthesis of CuO nanoparticles (NPs) using an extract of Rhus punjabensis as a reducing agent. NPs structural and composition analysis are evaluated by X-rays diffraction (XRD), Fourier transform... more
The present study reports ecofriendly synthesis of CuO nanoparticles (NPs) using an extract of Rhus punjabensis as a reducing agent. NPs structural and composition analysis are evaluated by X-rays diffraction (XRD), Fourier transform infrared, Energy dispersive spectroscopy, Scanning electron microscopy, Transmission electron microscopy, and Thermal analysis. The NPs have pure single phase monoclinic geometry with spherical structure and high stability toward heat and with average particle size of about 36.6 and 31.27 nm calculated by XRD and SEM, respectively. NPs are tested for antibacterial, protein kinase (PK) inhibition, SRB cytotoxic, and NF-κB activities. Antibacterial activity is observed against B. subtilis and E. coli. Significant PK and SRB cytotoxic activity is observed with some NF-κB inhibition. NPs IC values against HL-60 and PC-3 prostate cancer cells are 1.82 ± 1.22 and 19.25 ± 1.55 μg/mL. The results encourage further studies for antibacterial and anticancer drug d...
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The bioactivity and mechanical properties of hybrid composites of hydroxyapatite (HA) in cyclic olefinic copolymer (COC) also known commercially as TOPAS are investigated, first time, for regeneration and repair of the bone tissues. HA is... more
The bioactivity and mechanical properties of hybrid composites of hydroxyapatite (HA) in cyclic olefinic copolymer (COC) also known commercially as TOPAS are investigated, first time, for regeneration and repair of the bone tissues. HA is synthesized to obtain the spherically shaped nanoparticles in the size range of 60±20nm. Various concentrations of HA ranging from 1 to 30wt% are dispersed in TOPAS using sodium dodecyl sulfate (SDS) coupling agent for better dispersion and interaction of hydrophilic HA with hydrophobic TOPAS. Scanning electron microscope shows the uniform dispersion of HA≤10wt% in TOPAS and at higher concentrations >10wt%, agglomeration occurs in the hybrid composites. Tunable mechanical properties are achieved as the compressive modulus and strength are increased around 140% from 6.4 to 15.3MPa and 185% from 0.26 to 0.74MPa, respectively. Such increase in the mechanical properties of TOPAS is attributed to the anchoring of the polymer chains in the vicinity of...
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Algal biomass is an excellent renewable resource for the production of polymers and other products due to their higher growth rate, high photosynthetic efficiency, great potential for carbon dioxide fixation, low percentage of lignin and... more
Algal biomass is an excellent renewable resource for the production of polymers and other products due to their higher growth rate, high photosynthetic efficiency, great potential for carbon dioxide fixation, low percentage of lignin and high amount of carbohydrates. Algae contain unique metabolites which are transformed into monomers suitable for development of novel polyesters. This review article mainly focuses on algal bio-refinery concept for polyester synthesis and on exploitation of algae-based biodegradable polyester blends and composites in tissue engineering and controlled drug delivery system. Algae-derived hybrid polyester scaffolds are extensively used for bone, cartilage, cardiac and nerve tissue regeneration due to their biocompatibility and tunable biodegradability. Microcapsules and microspheres of algae-derived polyesters have been used for controlled and continuous release of several pharmaceutical agents and macromolecules to produce humoral and cellular immunity with efficient intracellular delivery.
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Abstract Copper–zinc–tin-sulfide (Cu 2 ZnSnS 4 , abbreviated as CZTS) is a direct band gap p-type semiconductor material with high absorption coefficient. Using oleylamine as solvent/stabilizing agent and metal chlorides and sulfur... more
Abstract Copper–zinc–tin-sulfide (Cu 2 ZnSnS 4 , abbreviated as CZTS) is a direct band gap p-type semiconductor material with high absorption coefficient. Using oleylamine as solvent/stabilizing agent and metal chlorides and sulfur particles as chemical precursors, CZTS based nanoparticles were produced and subsequently deposited as thin films on glass substrates via spin coating of the nanoinks. The effect of temperature on crystallite size and phase composition was assessed after the solution mixture was undercooled by 30, 70 or 90 °C. Upon cooling the solution from 230 to 140 °C i.e. by 90 °C, maximum refinement in the nanoparticles size was noticed with average size on the order of few nanometers. The morphological and compositional studies of the nanoparticles were performed by means of scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscopy techniques. Phase-pure CZTS formation was confirmed from fast Fourier transform (FFT) patterns and lattice fringes observed during HR-TEM examination. Characterization of the annealed spin coated films, made from nanoink containing ultrafine nanoparticles, indicated morphological changes in the film surface during air annealing at 350°C that can be attributed to depression of CZTS phase decomposition temperature. Spectrophotometric studies of the annealed films suggested quantum confinement effect through an associated increase in the band gap value from 1.34 to 2.04 eV upon reduction in the nanoparticle size caused by increasing the degree of undercooling to 90 °C.
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A significantly growing interest is to design a new strategy for development of bio-polyesters from renewable resources due to limited fossil fuel reserves, rise of petrochemicals price and emission of green house gasses. Therefore, this... more
A significantly growing interest is to design a new strategy for development of bio-polyesters from renewable resources due to limited fossil fuel reserves, rise of petrochemicals price and emission of green house gasses. Therefore, this review aims to present an overview on synthesis of biocompatible, biodegradable and cost effective polyesters from biomass and their prospective in different fields including packaging, coating, tissue engineering, drug delivery system and many more. Isosorbide, 2,4:3,5-di-O-methylene-d-mannitol, bicyclic diacetalyzed galactaric acid, 2,5-furandicarboxylic acid, citric, 2,3-O-methylene l-threitol, dimethyl 2,3-O-methylene l-threarate, betulin, dihydrocarvone, decalactone, pimaric acid, ricinoleic acid and sebacic acid, are some important monomers derived from biomass which are used for bio-based polyester manufacturing, consequently, replacing the petrochemical based polyesters. The last part of this review highlights some recent advances in polyester blends and composites in order to improve their properties for exceptional biomedical applications i.e. skin tissue engineering, guided bone regeneration, bone healing process, wound healing and wound acceleration.
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AbstractTwo extruded bars of the nickel base mechanically alloyed materials MA 6000 and MA 760 have been zone recrystallised in a calibrated gradient furnace. Selected area channelling patterns in the scanning electron microscope have... more
AbstractTwo extruded bars of the nickel base mechanically alloyed materials MA 6000 and MA 760 have been zone recrystallised in a calibrated gradient furnace. Selected area channelling patterns in the scanning electron microscope have been employed to study the crystallographic texture of the grains of large aspect ratio produced by zone annealing, and microbeam electron diffraction has enabled the orientations of the submicrometre sized equiaxed grains in the material behind the (secondary) recrystallisation front to be studied. In both alloys a curved secondary recrystallisation interface is observed, with the surface recrystallising at a lower temperature than the interior. This is considered to result indirectly from the strain gradients occurring during extrusion. A texture is present, and reasons for this are discussed. In MA 6000 progressive grain rotation towards has been measured behind the recrystallisation interface, although this is not observed in MA 760 as it transforms at a lowe...
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In this work, hydroxyapatite (HA) nanorods were synthesized by simple one step wet precipitation method followed by their rapid surface functionalization via aminopropyltriethoxysilane (APTS) to give modified (HA-APTS) product.... more
In this work, hydroxyapatite (HA) nanorods were synthesized by simple one step wet precipitation method followed by their rapid surface functionalization via aminopropyltriethoxysilane (APTS) to give modified (HA-APTS) product. Functionalized hydroxyapatite (HA-APTS) holds amino groups on their surface that can be further functionalized with other bioactive molecules. The extent of functionalization of HA was studied under three different processing conditions; at room temperature, at 80 °C and under microwave condition (600 W). Three different temperatures have been use for the purpose of comparison between the functionalized products so that we can judge that whether there is any effect of temperature on the final products. In the last we conclude that temperature has no effect. So microwave condition is best to carried out the functionalization in just 5 min.
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Among the bioactive ceramics Hydroxyapatite (HA) is an inorganic, insoluble calcium phosphate salt and owing to its biocompatibility and osteoconductive properties it is a desirable implant material. Hydroxyapatite (HA) is one of the most... more
Among the bioactive ceramics Hydroxyapatite (HA) is an inorganic, insoluble calcium phosphate salt and owing to its biocompatibility and osteoconductive properties it is a desirable implant material. Hydroxyapatite (HA) is one of the most stable crystal structures of the calcium phosphates. Hydroxyapatite (HA) is the principal bioactive The aim of this work is to synthesize phase pure hydroxyapatite by the wet precipitation method which is the simplest method for the synthesis of hydroxyl apatite. To evaluate the phase purity of hydroxyapatite and to know the effect of stirring speed and time on the phase purity. To study the morphology of HA particles and its size variation with stirring time. To determine how stirring time effect of the crystallite size and crystallinity degree. To evaluate the phase purity of hydroxyapatite and to know the effect of refluxing time on the phase purity. To study the morphology of HA particles and its size variation with refluxing time. To examine h...
Nanoflowers are desirable in light driven applications like Dye Sensitized Solar Cells (DSSCs) due to their large surface area and greater light absorption capabilities. An instant, simple, cheap and environment friendly method of... more
Nanoflowers are desirable in light driven applications like Dye Sensitized Solar Cells (DSSCs) due to their large surface area and greater light absorption capabilities. An instant, simple, cheap and environment friendly method of preparing titanium dioxide nanoflowers is presented. The nanoflowers are produced in a time as short as 5 minutes in aqueous conditions without the use of hazardous hydrofluoric acid or organic surfactants at 1 atm. pressure and low temperature of 100°C. Titanium dioxide commercial nanopowders are treated with microwaves in an aqueous sodium hydroxide solution for small durations. The resulting powders are annealed at 450°C in air and characterization is performed using XRD, SEM and Raman spectroscopy.
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This research aims to optimize the process parameters of plasma arc welding for welding of dissimilar metals: austenitic stainless steel SS-304 L and low carbon steel A-36. It investigates the effect of welding current and welding speed... more
This research aims to optimize the process parameters of plasma arc welding for welding of dissimilar metals: austenitic stainless steel SS-304 L and low carbon steel A-36. It investigates the effect of welding current and welding speed on the quality of the welded joints. The quality characteristics like bead geometry, microstructure, hardness, ferrite measurement and tensile test are considered for qualification of the welded samples. Welded specimens were prepared both with and without filler material. These specimens were mechanically tested and analyzed using metallographic techniques. Based on the results, suitable welding parameters were found to be 45 A and 2 mm/s for samples prepared with and without filler wire. An all-martensitic weld zone structure was obtained for direct fusion. However, a complex heterogeneous microstructure was obtained by using austenitic stainless steel filler wire E 309 L. Hardness of directly fused sample was observed to be significantly higher co...
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ABSTRACT CoFe2O4 nano particles and CoFe2O4-rGO nano hybrids were synthesized via 1-hexanol assisted insitu reduction and growth process under solvothermal conditions for the first time and were characterized. Morphological and... more
ABSTRACT CoFe2O4 nano particles and CoFe2O4-rGO nano hybrids were synthesized via 1-hexanol assisted insitu reduction and growth process under solvothermal conditions for the first time and were characterized. Morphological and dimensional analysis showed spherical nano particles of average size 15-27nm. Magneto dielectric spectroscopy revealed the formation of ultra low dielectric constant of 3.21 (@1MHz) nano particles with negligible loss of as low as 0.03 (@3GHz). Nano hybrid were also tailored to show electromagnetic absorption from 12MHz-3GHz otherwise absent at this frequency.
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ABSTRACT Cellulose acetate (CA) is a widely applied glassy polymer in the preparation of gas separation membranes. In the present study, hybrid membranes were prepared by incorporating silica (Si) and silica functionalized with... more
ABSTRACT Cellulose acetate (CA) is a widely applied glassy polymer in the preparation of gas separation membranes. In the present study, hybrid membranes were prepared by incorporating silica (Si) and silica functionalized with p-tetranitrocalix[4]arene (Si-CL) into the CA matrix, and their gas permeation abilities were explored with regard to CO2, N2 and CH4 gases. The diffusion-induced phase separation (DIPS) method was adopted to make pure CA, CA/Si, and CA/Si-CL hybrid membranes. The concentration of Si-CL was varied as 10 wt%, 20 wt% and 30 wt% in the hybrid membranes. The analytical techniques employed for membrane characterization were Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X ray-diffraction (XRD) analysis. The proper interaction of Si and Si-CL was confirmed by FTIR analysis. However, the homogenous surface textures of CA/Si, and CA/Si-CL hybrid membranes were evaluated through SEM. Furthermore, AFM analysis was performed to examine the surface roughness of these hybrid membranes. The changes in the crystallinity of CA were also examined by XRD analysis after adding Si and Si-CL. Moreover, the tensile strength of the CA/Si hybrid membrane was found to be better than that of CA/Si-CL hybrid membranes. CO2, CH4 and N2 gases were used for gas permeation experiments at 400 kPa. Among CO2 and CH4 gases, the permeability of N2 was high in CA/Si-CL hybrid membranes, and N2/CO2 selectivity of these membranes was 22.6.
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ABSTRACT Bone implants are widely used to treat patients due to trauma in different causalities. The major types of bone implants are plates known as Dynamic Compression Plates (DCP) and nails, both made of stainless steel (AISI 316L... more
ABSTRACT Bone implants are widely used to treat patients due to trauma in different causalities. The major types of bone implants are plates known as Dynamic Compression Plates (DCP) and nails, both made of stainless steel (AISI 316L Grade). In Pakistan both local made and foreign made (DCP) are available. The unit price of foreign made DCP is about 8 to 10 times that of the local made, however, no comprehensive study has been done on the comparison of these plates. An in-depth analysis was performed to compare the essential properties of six different brands of DCP including two foreign, two local and two unknown brands. These properties included mechanical properties, such as bending stiffness, yield strength, modulus of elasticity and hardness. Compositional analysis and various dimensions of plate important for bone healing process were also compared. The results show that all plates have similar mechanical properties. The compositional analysis showed some variations from the ASTM standards for most of the plates. The dimensional analysis of plates showed that Slot Width and Land were within range for most of the plates but the Spherical Radius was out of range for all the plates. Generally, all plates have no major differences in their properties, material and shape.
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ABSTRACT Thin film multilayer anti-reflection coatings (SÍO2/SÍ/S1O2) having thicknesses 286/571/143nm were deposited by RF magnetron sputtering deposition technique on 0.5mm thick Si(100)-substrates. Post-deposition annealing is also... more
ABSTRACT Thin film multilayer anti-reflection coatings (SÍO2/SÍ/S1O2) having thicknesses 286/571/143nm were deposited by RF magnetron sputtering deposition technique on 0.5mm thick Si(100)-substrates. Post-deposition annealing is also carried out in the temperature range 150-650°C for 4hr at the rate of 10°C /min. Si Optical window was designed at 4.22πι wavelengths and correlated with modeling software. The films are transparent in the 3-5um band of the electromagnetic spectrum, firmly adhered to the substrate. The prepared multilayer thin films are characterized optically and structurally using a spectrophotometer, an atomic force microscope, x-ray diffraction and a scanning electron microscope. Optical and structural characterizations show that the %transmittance is between 60% and 75%, no appreciable change in crystal structure and roughness of coatings vary between 9 and 25 nm when annealed in the temperature range of 150-650°C. Local elemental characterization on the surface of the thin film was carried out using energy dispersive spectroscopy. The quantitative result of energy dispersive spectroscopy has also shown that the ratio of Si to O on the film is 0.67:1.
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The present work deals specifically with the development of zirconium oxide thin film coatings on the stainless steel orthodontic bracket system by sputtering technique. Thin films of zirconium oxide have been deposited on injection... more
The present work deals specifically with the development of zirconium oxide thin film coatings on the stainless steel orthodontic bracket system by sputtering technique. Thin films of zirconium oxide have been deposited on injection molded stainless steel substrates using sputtering under controlled temperature and environment conditions. The deposited films, 1.5 µm in thickness, were found to have a predominantly tetragonal structure with grain size of about 5 nm. The grain size was found to increase only slightly with increasing heat treatment time at 650°C. It has been shown that thin-film zirconia coatings with stable structure and good adhesion along with very low friction coefficient could be produced.
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Nanostructured Fe-Co based alloys are believed to be good candidates for imparting improved magnetic behavior in terms of higher permeability, lower coercivity, reduced hysteresis loss and higher Curie temperatures. In the present work,... more
Nanostructured Fe-Co based alloys are believed to be good candidates for imparting improved magnetic behavior in terms of higher permeability, lower coercivity, reduced hysteresis loss and higher Curie temperatures. In the present work, Fe-Co alloys with Ni additions were prepared using mechanical alloying (MA). Grain size and internal strain in the MA powders was measured using X-ray diffraction. It has been shown that the grain size could be reduced down to less than 5 nm in these alloys. Nanocrystalline materials thus obtained were also evaluated for magnetic behavior and the influence of grain size and internal strain on the magnetic properties has been discussed.
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Research Interests: Solid State Physics, Scanning Electron Microscopy, Transparent Conducting Oxide Materials, Nanotechnology, Crystal structure, and 13 moreZinc Oxide, Copper, Thin Film, Nanoscience, ZnO (Zinc Oxide), CDS, Thin Film Solar Cell, Cost effectiveness, X ray diffraction, Natural, Transmittance, Chemical bath deposition, and Physical Properties
Nanostructured alloys have great potential as soft magnetic materials. In particular, nanocrystalline Fe-Co based alloys are believed to be good candidates for imparting improved magnetic behavior in terms of higher permeability, lower... more
Nanostructured alloys have great potential as soft magnetic materials. In particular, nanocrystalline Fe-Co based alloys are believed to be good candidates for imparting improved magnetic behavior in terms of higher permeability, lower coercivity, reduced hysteresis losses and higher Curie temperatures. In the present work, Fe-50at.%Co alloy powders have been prepared using mechanical alloying (MA) in a planetary ball mill under controlled environment. The particle size and morphology of MA powders was investigated using scanning electron microscopy. The crystal size and internal strain was measured using X-ray diffraction. It has been shown that the crystal size could be reduced down to less than 15 nm in these alloys. Finally, the influence of grain size and internal strain on the magnetic properties has been discussed.
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ABSTRACT Nano crystalline hydroxyapatite (HA) particles were synthesized through chemical precipitation method. This study is purely based on the rapid synthesis of nano HAP ceramics with controlled size and morphologies using Sodium... more
ABSTRACT Nano crystalline hydroxyapatite (HA) particles were synthesized through chemical precipitation method. This study is purely based on the rapid synthesis of nano HAP ceramics with controlled size and morphologies using Sodium Dodecyl Sulphate ( ...
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Abstract Zn-(FeO 2 ) 2 –graphene smart nano-composites were synthesized using a novel modified solvothermal synthesis with different percentages of graphene. The structure of the nanocomposite was confirmed through X-ray diffraction,... more
Abstract Zn-(FeO 2 ) 2 –graphene smart nano-composites were synthesized using a novel modified solvothermal synthesis with different percentages of graphene. The structure of the nanocomposite was confirmed through X-ray diffraction, micro-Raman scattering spectroscopy, Ultraviolet–Visible spectroscopy, and Fourier transform infrared spectroscopy. The structural growth and morphological aspects were analyzed using scanning/transmission electron microscopy, revealing marvelous micro-structural features of the assembled nano-system resembling a maple leaf. To determine the composition, energy dispersive spectroscopy and X-ray photoelectron spectroscopy were used. Microwave magneto-dielectric spectroscopy revealed the improved dielectric properties of the nano-composite compared to those of the parent functional nanocrystals. Temperature gradient dielectric spectroscopy was used over the spectral range from 100 Hz to 5 MHz to reveal the phenomenological effect that the nanosystem flips from its usual semiconductor nature to a metallic nature with sensing temperature. Electrical conductivity and dielectric analysis indicated that the dielectric loss and the dielectric permittivity increased at room temperature. This extraordinary switching capability of the functionalized graphene nanosystem opens up a new dimension for engineering advanced and efficient smart composite materials.
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Cellulose acetate–titania (CA–TiO2) nanoparticles blended membranes were fabricated using diffusion-induced phase separation process to observe the effect of inorganic nanofillers on the surface topography and gas permeation properties of... more
Cellulose acetate–titania (CA–TiO2) nanoparticles blended membranes were fabricated using diffusion-induced phase separation process to observe the effect of inorganic nanofillers on the surface topography and gas permeation properties of CA membrane. Self-synthesized TiO2 nanoparticles using sol gel reflux condensation were employed as nanofillers, which is the anatase phase of TiO2 with crystallite size of 5–10 nm. The synthesized membranes were characterized using scanning electron microscopy and atomic force microscopy techniques to study the nanoscale distribution of TiO2 nanoparticles, surface roughness, and pores generation in blended membranes, with increasing nanoparticles' concentration in polymer matrix. The permeability of CO2 was found to be increased for CA–TiO2 blended membranes. The CO2/CH4 selectivity up to 23.3 was documented. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
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Presenting instant microwave-synthesized hierarchical nanostructures (HNSs) of titania with huge surface area and light scattering, thus greater absorption, for better performance in DSSCs.
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ABSTRACT Titania possesses a band gap of ~3.2 eV, whereas the work function of graphene ~4.5 eV exists near the lowest unoccupied molecular orbital (LUMO) of titania. The photoexcitation of electrons in titania (TiO2) is possible only... more
ABSTRACT Titania possesses a band gap of ~3.2 eV, whereas the work function of graphene ~4.5 eV exists near the lowest unoccupied molecular orbital (LUMO) of titania. The photoexcitation of electrons in titania (TiO2) is possible only under the ultraviolet radiation. If such conversion is required in visible light range, band gap has to be lowered below 3.1 eV. This research work hence aims at lowering the band gap of titania thin films by incorporation of graphene nanosheets. Graphene was synthesized using modified Hummer׳s method. Oxidation of graphite was confirmed by X-ray diffraction (XRD) revealing a peak at 11.8° with interplanar distance of 7.5 Å and energy dispersive X-ray spectroscopy (EDS) analysis. Atomic force microscopy (AFM) analysis revealed exfoliation of single layer graphene oxide nanosheets having thickness of 0.6–1.0 nm. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed the reduction of graphene oxide by revealing removal of carbonyl group (C 2
Research Interests:
Research Interests:
Alumina was coated on Ti6Al4V alloy by atmospheric plasma spraying. Surface and cross sectional analysis of the coating by SEM showed that diameter and thickness of splat was greatly influenced by arc current and stand-off distance. In... more
Alumina was coated on Ti6Al4V alloy by atmospheric plasma spraying. Surface and cross sectional analysis of the coating by SEM showed that diameter and thickness of splat was greatly influenced by arc current and stand-off distance. In turn, this variation in splat morphology had effect on evolution of α-Al2O3 and γ-Al2O3 phases as revealed by XRD. Higher proportion of required γ-Al2O3 phase was achieved at stand-off distance of 130 mm and arc current of 500A.