This paper aims at introducing new natural fibers used as fillers in a polymeric matrix enabling production of economical and lightweight composites for load carrying structures. An investigation of ...the extraction procedures of vakka (
Roystonea regia), date and bamboo fibers has been undertaken. The cross-sectional shape, the density and tensile properties of these fibers, along with established fibers like sisal, banana, coconut and palm, are determined experimentally under similar conditions and compared. The fibers introduced in the present study could be used as an effective reinforcement for making composites, which have an added advantage of being lightweight.
As the world's fastest growing major economy and home to nearly one-fifth of the worlds population, India a vibrant democracy is in the midst of a profound transformation and rapid urbanization. ...Urbanization improves the quality of life of people while promoting economic growth; however it also increases energy consumption and is capable of generating an energy crisis. Urbanization has a significant impact on Carbon Dioxide (CO2) emissions as well. This paper empirically investigates the temporal, dynamic and causal relationships between urbanization, energy consumption and emissions. The study also aims to understand the urbanization process in India, in terms of the level and tempo of urbanization and the urban growth morphology, by utilizing the census data of 1901–2011. The rise in energy consumption and resulting emissions in the context of rapid urbanization is also reviewed. To address these problems the study recommends a series of measures and a set of strategies that include energy intensity and emission intensity reduction measures through continuous monitoring, information feedback systems, introduction of industrial energy quota management, incentives for energy efficient facilities, shutting down of inefficient facilities, and setting up of smart residential buildings. Reduction of distribution and transmission losses by investing in smart grids is also highly recommended.
Prof B Ramamurthi was a pioneer of Indian neurosurgery and a major force in the development of Indian neuroscience. Founding the Madras Institute of Neurology and later the A Lakshmipathi ...Neurosurgical Centre (ALNC), both at Madras (or Chennai as it is now called), he developed centres of excellence in his career that spanned over five decades. During this period of time he made Madras, a destination for neurosurgery and neuroscience. Along with his colleagues a large number of publications were produced which influenced the world. Notable among his contributions were those in Stereotaxy for movement disorders, epilepsy, pain and psychiatric illness. He also had notable contributions in brain tumours especially acoustic neurinomas and pituitary tumours. His papers on the low incidence of aneurysms is still quoted widely. Head injuries formed a major part of the neurosurgical work and major contributions were made in that field too. As a developing country with socio-economic issues, infections of the nervous system were seen commonly. His publications on tuberculomas of the brain are noteworthy. He was intrigued by the neurophysiological basis of consciousness. He writings on the subject reflect his attempt to bring together ancient eastern thoughts and concepts of consciousness and life and western science. In the later part of his career he spoke on ethics in and the changing milieu of neurosurgery. While contributions to spinal surgery were not seen in the first half of his career, he along with his colleagues from ALNC published original articles on spinal surgery especially tumours and OPLL. Prof B Ramamurthi, has not only influenced, taught and mentored, during his lifetime, a great many neuroscientists, but he also continues to do so through his publications which continue to be relevant in todays world. A glimpse into his contributions show us how without the technology of today a lot was achieved - and we need to see that, to inspire us to achieve more and to strive for greater heights.
A study has been carried out to investigate the tensile, flexural and dielectric properties of composites made by reinforcing vakka as a new natural fibre into a polyester resin matrix. The fibres ...extracted by retting and manual processes have been used to fabricate the composites. These composites are tested for tensile, flexural and dielectric properties and compared with those of established composites like sisal, bamboo and banana made under the same laboratory conditions. The composites are fabricated up to a maximum volume fraction of fibre of 0.37 in the case of tensile testing, and 0.39 for flexural and dielectric testing. It has been observed that the tensile properties increase with respect to volume fraction of fibre for vakka fibre composite and are also more than those of sisal and banana composites and comparable to those of bamboo composites. The flexural strength of vakka fibre composite is more than that of banana composite and is closer to sisal fibre composite with respect to the volume fraction of fibre, where as the flexural modulus is much higher than those of banana and sisal fibre composites and also very much closer to bamboo fibre composites. The dielectric strength of vakka fibre composite increases with increase in volume fraction of fibre in the composite unlike the case of sisal, bamboo and banana composites. The dielectric strength being a unique feature of vakka fibre composite, can be suggested for electrical insulation applications.
Elephant grass stalk fibers were extracted using retting and chemical (NaOH) extraction processes. These fibers were treated with KMnO4 solution to improve adhesion with matrix. The resulting fibers ...were incorporated in a polyester matrix and the tensile properties of fiber and composite were determined. The fibers extracted by retting process have a tensile strength of 185 MPa, modulus of 7.4 GPa and an effective density of 817.53 kg/m3. The tensile strength and modulus of chemically extracted elephant grass fibers have increased by 58 and 41%, respectively. After the treatment the tensile strength and modulus of the fiber extracted by retting have decreased by 19, 12% and those of chemically extracted fiber have decreased by 19 and 16%, respectively. The composites were formulated up to a maximum of 31% volume of fiber resulting in a tensile strength of 80.55 MPa and tensile modulus of 1.52 GPa for elephant grass fibers extracted by retting. The tensile strength and the modulus of chemically extracted elephant grass fiber composites have increased by approximately 1.45 times to those of elephant grass fiber composite extracted by retting. The tensile strength of treated fiber composites has decreased and the tensile modulus has shown a mixed trend for the fibers extracted by both the processes. Quantitative results from this study will be useful for further and more accurate design of elephant grass fiber reinforced composite materials.
•Machining of titanium alloys is difficult due to its tendency of breakage while machining.•Vibration of drill bit was measured with non contact sensor i.e. LDV.•Influencing parameters on the surface ...roughness, flank wear and drill vibration were identified.•Multi response optimization was done using response surface methodology.•Empirical equations for drilling characteristics were developed.
Machining of titanium alloys is difficult due to their low elasticity, high formability and tendency of breakage. In drilling of TI-6Al-4V alloy, drill bits are subjected to chatter vibration and it causes poor surface finish and tool failure. In this study, effect of drilling parameters such as spindle speed, helix angle and feed rate on surface roughness, flank wear and acceleration of drill vibration velocity was investigated using Response Surface Methodology. A Laser Doppler Vibrometer (LDV) was used to measure vibration of drill bit in the form of Acousto Optic Emission (AOE) signal. And these signals were transformed into time domain with different time frequency zones using a high speed fast Fourier transformer. Experimental data were analyzed using Response Surface Methodology (RSM) to identify significant parameters on surface roughness, flank wear and acceleration of drill vibration velocity. A multi response optimization was performed to optimize drilling parameters for minimum surface roughness, flank wear and acceleration of drill vibration velocity. Optimum cutting parameters were found as 26.16 degrees of helix angle, 10.0 mm/min of feed rate and 600rpm of spindle speed.
The dearth of information about the fabrication of flexible polyaniline and graphite-based microporous and low-cost thermoelectric generators using screen printing for low-temperature applications ...has motivated us to undertake this research work. Polyaniline and graphite composite inks were formulated using cellulose acetate as resin and diacetone alcohol as the solvent. In this work, we have studied the influence of ink ingredients on the thermoelectric properties of composite inks. Diacetone alcohol improved the electrical conductivity of polyaniline by 7.9 times. The carrier concentrations and carrier mobility of composite ink were enhanced by 2.8 times. Simultaneously, cellulose acetate increased resistivity and carrier mobility of polyaniline by 13 and 44 times, respectively. Graphite improved the crystallinity but reduced carrier mobility, carrier concentration, and bandgap of the composite inks. Screen-printed porous ink film structure reduced the thermal conductivity of PANI ink by 11 times at 333 K. The maximum Seebeck coefficient and power output exhibited by the fabricated thermoelectric generator were 244.34 μV/K and 4.31 nW, respectively at 77 K. Present work explored fabrication and characterization of low cost, flexible polyaniline and graphite composite ink-based thermoelectric generator with improved Seebeck coefficient and power output for low-level heat energy conversion.
•Polyaniline/graphite ink-based flexible thermoelectric generator is screen printed.•Cellulose acetate resin improved resistivity and carrier mobility of polyaniline.•Diacetone alcohol solvent enhanced electrical conductivity of polyaniline.•Graphite in polyaniline reduced carrier concentration, mobility, and bandgap.•The porous leg thermoelectric generator produced a power output of 4.31 nW at 77 K.
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•Synthesis of starch capped ZnS nanoparticles following green chemistry principles.•Starch capping ensured by TEM, HRTEM and FTIR studies.•Quantum size effects observed in optical ...absorption studies.•Progressive quenching of surface states with starch addition observed in PL spectra.
Following a green synthesis method, zinc sulfide (ZnS) nanoparticles were prepared by chemical co-precipitation technique using starch as capping agent. Microwave irradiation was used as heating source. X-ray diffraction studies indicated that nanopowders obtained were polycrystalline possessing ZnS simple cubic structure. Transmission electron microscopic studies indicated that starch limits the agglomeration by steric stabilization. Interaction between ZnS and starch was confirmed by Fourier transform infrared spectroscopy as well as Raman scattering studies. Quantum size effects were observed in optical absorption studies while quenching of defect states on nanoparticles was improved with increase in starch addition as indicated by photoluminescence spectra.
Zinc oxide (ZnO) thin films were sol-gel spin coated on glass substrates and annealed at various temperatures from 300–500°C. Zinc acetate dihydrate (ZAD), monoethanolamine (MEA), and ...2-methoxyethanol were used as the starting materials, stabilizer and solvent, respectively. The effect of annealing temperature on the structural and optical properties of the ZnO thin films was investigated by X-ray diffractometer (XRD), atomic force microscope (AFM), UV–VIS spectrophotometry and ellipsometry. The XRD results showed the films to have a preferential c-axis orientation, whereas the AFM results confirmed a columnar structure. The surface roughness increased with the increase in annealing temperature. Parameters such as ratio of free charge carrier concentration to effective mass (N/m*) and plasma frequency (ωp) were determined from the transmittance graph using the Wemple di Domenico model. Both N/m* and ωp were noticed to reduce with the increase in annealing temperature. Band gap decreased with the increase in the annealing temperature indicating absorption edge shift towards the red region.
The work focuses on exploring the effect of the concentration of Sm dopant (0.2–0.6 at.%) on structural, optical and photocatalytic properties of the spin coated titania based thin films annealed at ...different temperatures. The optical interpretation involves the influence of Sm doping on optical constants and luminescence behaviour of the samples. The comprehensive work on optical bandgap, Urbach energy and electron-phonon interaction strength was conducted for Sm doped samples. The optical band gap was found to increase with the increasing concentration of Sm, but decreased with high temperature annealing. Using ellipsometry measurement, refractive index of the samples was obtained. The orbital level information was gathered using X-Ray Photoelectron Spectroscopy (XPS) study with a special emphasis on the evolution of physico-chemical properties as function of Sm doping. The XPS study confirms the presence of Sm in the titania host material and it helped in estimating defects induced by Sm doping. The photocatalytic study of Sm doped titania thin films was carried out by using methylene blue (MB) and Rhodamine B (RhB) dye and we have found an enhanced photocatalytic activity for the 0.4 at.% Sm doped samples.
