Abstract: Ethical research that ensures the enhancement of quality of human life for present and future generations is the need of the day. This inherits the typical requirement to impose zero or minimal stress on the environment. Currently, planet earth is witnessing global warming and largely unpredictable weather changes, primarily due to greenhouse gas emissions. Transportation sector is one of the major engineering sectors contributing to greenhouse gas emissions. One way to mitigate/minimize these emissions is to use lightweight materials in the construction of vehicles for use in land, water, aerospace and space applications. Towards this, magnesium based materials are viable options which are suitable to replace aluminum based materials allowing ~ 35% weight saving on a component basis. As magnesium is abundant in nature and is a nutritional element, its availability and recyclability is not an issue. Accordingly, this paper will focus on the development of magnesium based nanocomposites capable of replacing conventional materials in multiple engineering and biomedical applications.
Abstract: Carbon/carbon composite xerogels are prepared by a vacuum drying technique whereas a carbon cryogel is synthesized by a freeze drying technique to compare the effect of these drying methods at the selective synthesis condition. Resorcinol and formaldehyde are used to prepare a matrix phase and cotton fibers are acted as a disperse phase of the carbon/carbon composite xerogels. Here resorcinol and formaldehyde is utilized to synthesize the carbon cryogel only. The carbon/carbon composite xerogels and the carbon cryogel were analyzed by a nitrogen adsorption apparatus and a field emission scanning electron microscope. The results support that the vacuum drying can decrease the pore shrinkage despite of the gas-liquid interface. The porous properties of the carbon xerogel is quite equivalent to the porous properties of the carbon cryogel. When the porous properties of carbon xerogels are considered, their porous properties can be preserved at the high porosity until 0.15 g/g of the cotton fibers/resorcinol ratio. At 0.25 g/g of this ratio, the porous properties start decreasingly.
Abstract: TiO2 nanorod arrays (TNRs) films were fabricated on the polished Ti substrates using hydrothermal and then annealed for 2 h in air at 300°-500°C. The films were characterized by XRD and FESEM. The photocatalytic activities to degrade methylene blue (MB) in solution were determined, expecting these activities to correlate with the hydrophobic property. The experiment showed that rutile peaks recrystallized at the annealing temperature, with the crystallinity increase with increasing annealing temperatures. The TNRs films annealed at 500 oC had a comparatively high crystallinity of rutile phase as well as the highest photocatalytic activity of the films prepared. Surface wettability was studied by measuring the contact angle of the liquid interface which showed hydrophobic nature as water contact angles were greater than 120°. The results can be concluded that as-prepared TNRs film was annealed at 500 oC exhibits excellent hydrophobicity for water molecules and the highest photocatalytic activity on the degradation of MB under UV irradiation.
Abstract: Peptide – mediated biomineralization is an emerging and promising biomimetic approach for the synthesis of nanomaterials. This nature – inspired technique of producing inorganic nanostructures depends on the biomineralization peptide to control the shape and morphology of the prevailing inorganic nanostructure. One of the challenges in peptide – mediated biomineralization is controlling the 3D arrangement and orientation of the peptide. Recently, we have developed a peptide platform that can specify and direct the geometric arrangement and spatial orientation of the biomineralization peptide. The peptide platform is composed of two segments: a metal binding sequence, and the tetramerization domain of the tumor suppressor p53 protein, which acts as the oligomerization control element. The resulting fusion peptide exhibits a spatially – fixed and well – controlled assembly of the palladium binding sequence. This present study demonstrates the utility and efficacy of this peptide platform to bimetallic materials. Monodispersed 5 nm bimetallic PdAg nanoparticles were synthesized using the oligomerization – controlled biomineralization peptide. The synthesis was carried out in an aqueous environment, void of harsh reagents. When other fusion biomineralization peptides were used to synthesize bimetallic PdAg nanoparticles, less ordered nanoparticles were yielded. The results highlight the importance of controlled assembly on bimetallic nanoparticle formation through biomineralization. The presented method offers a straightforward manner of creating monodispersed and extremely small nanoparticles, which are useful in a wide array of applications.
Abstract: Rice husk (RH) is the largest cereal crop that represents a crucial agricultural waste founded all over the world. There is a vast quantity of RH generated, any amount of paddy contains at least 20% of husk. Consequently, open burning processes were often lead to great environmentally hazard. This work investigates a new technique for the production of cellulose nanocrystals (CNC) using the following route; Alkaline treatment using sodium hydroxide (2% NaOH), followed by bleaching with hydrogen peroxide (2% H2O2), and finally grinding process. In this new process, we avoided the long-lasting hydrolysis step. The extracted CNC was characterized using different techniques. Morphological structural composition of the extracted CNC was inspected using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy displayed the elimination of non-cellulosic constituents. X-ray diffraction (XRD) analysis reported the crystallinity of each molecule group. Thermogravimetric analysis (TGA) was completed to inspect the thermal stability of the extracted cellulose nanocrystals.
Abstract: A novel, simple and environmental friendly approach to fabricate silver nanoparticles (AgNPs) on mesoporous silica nanoparticles (MSNs) using tyrosine (Tyr) as biological reducing agent was developed. The functionalization of Tyr with MSNs (Tyr-MSNs) (150 nm in length) by the sol-gel process was confirmed by the characteristic peaks of amino, carboxyl and silanol groups appeared in FTIR spectrum and the change of the zeta potential from 0 mV at pH 2 to-60 mV at pH 12. Then, AgNPs were formed on the surface of Tyr-MSNs (Tyr-MSN@AgNPs) via only reducibility from phenolic group of Tyr and catalytic activity from base at room temperature. TEM images and UV-Visible absorption band at 420 nm supported the obtained AgNPs (18 nm at pH 11) were tightly bound to Tyr-MSNs even after centrifugation at high speed. These Tyr-MSN@AgNPs would be potentially used as drug carrier in biomedical applications.
Abstract: This paper presents the results obtained for incorporating the Al65Cu24Fe11 material with the conventional TiO2 as the electron injection layer in dye-sensitized solar cells. The icosahedral phase of the Al-Cu-Fe system has attractive physical and optical properties at the target composition, and is obtained by synthesizing the material via the facile high energy ball milling process to ensures the highest possible interdiffusion of elemental powders, followed by heat treatment. The evolution of the i-phase is confirmed via X-ray diffraction, scanning electron microscopy and energy dispersive x-ray spectroscopy. The optical absorption and electrical properties of the compound are investigated by spectrometry, four probe measurement and Mott-Schottky analysis, respectively. Different cells with different percentages (x value) of (TiO2)1-x/(Al65Cu24Fe11)x are constructed and tested to obtain the electrical characteristic curves, efficiency and fill factor to quantify the effect of the proposed material mixture.
Abstract: The effects of stretchable rotating flat surface on the time dependent 3-dimensional boundary layer flow of magnetic nanoliquid in the presence of thermal radiation have been investigated. The modelled set of nonlinear coupled ODEs governing the flow is solved numerically by finite difference scheme and shooting technique. For understanding the effects of geothermal viscosity, stretching parameter and thermal radiation on the flow and temperature fields, a range of Prandtl number is taken into account. The heat transfer rate and skin frictions due to the above physical parameters are also computed. A significant enhancement in the resistance of the fluid flow is noticed due to the viscosity variations and the stretching of the plate. Further, the heat dissipation becomes faster with the enhancement of the thermal radiation and the Prandtl number.
Abstract: The prime purpose of the current study was to investigate the consequence of surfactant on the kinematic viscosity, thermal conductivity, and stability of MgO-oil based nanofluid. Magnesia (MgO) nanoparticles were prepared by the wet chemical method. Structural and morphological analysis of synthesized nanoparticles were performed via X-ray diffraction (XRD) and Transmission electron microscope (TEM). Subsequently, nanofluid was prepared at a solid concentration of 0.025% in presence of various surfactants with the aid of ultrasonic technique. The impact of the different surfactants (Cetyl Trimethyl Ammonium Bromide (CTAB), Poly Vinyl Pyrrolidone (PVP), Poly Vinyl Alcohol (PVA), and Oleic Acid) on the nanofluid stability was tested. It was evident that CTAB and PVA surfactants establish the most stable prepared MgO-oil based nanofluid. The experiments revealed that the maximum UV–Vis absorbance of the solution corresponds to the dispersion of CTAB in the base fluid.
Abstract: The reduction of ilmenite by a gas comprising of CNG, hydrogen and nitrogen mixture was investigated by experimental and kinetic modeling in MATLAB. The CNG flow time was varied from 15 to 45 minutes at the temperatures of 1100-1200°C for 1-3 hours. In order to predict the extent of reduction, a shrinking core model (SCM) and crackling core model (CCM) were employed for the kinetic modeling. The results showed that the extent of reduction of 80% was achieved by using a CNG flow time of 45 minutes at 1200°C for 1 hour. The kinetic modeling for non-isothermal SCM at the same conditions gave a predicted value of 87%. The CCM gave a predicted value of about 100% at the same conditions. The non-isothermal SCM showed a closer trend to the experimental results. The deviation between SCM and CCM with the experimental data was attributed to porosity, thermodynamic properties and minute thermal fluctuations within the sample during the reduction process.