Shape adaptive grinding (SAG) is a relatively newer finishing process to achieve nanoscale surface roughness of difficult to machine materials. The wear mechanism of zirconia-alumina polishing pads ...is investigated after performing SAG and chemical assisted SAG (CA-SAG) for the finishing of WC-Co coating. The numbers of active abrasive particles in SAG increases due to the existence of the elastic medium and that leads to a smaller depth of penetration. This phenomenon along with the presence of tough zirconia phase in abrasive particles limits the possibility of the fracture wear. Smooth and elongated grooves along the finishing direction are observed on the wear flats which indicate that the plastic deformation is the predominant wear mechanism rather than micro-fracture. A phenomenological model for the attritious wear of the polishing pads is developed using the experimental findings. The radial pad wear and pad loading are analysed quantitatively using surface texture parameters. The wear mechanism in CA-SAG is immensely affected by the use of chemical reagent in the process. A substantial pad loading is observed owing to the deposition of the passivation layer in the inter-grit spaces. Thus, shelling of the abrasive particles and pad loading are identified as the dominant wear mechanisms.
•Number of active abrasive particles in SAG is 30% higher than grinding wheel.•A model is proposed to assess the attritious wear and thermal aspect in SAG.•Mostly attritious wear is taken place owing to the presence of tough zirconia phase.•Pad loading and grain pull out are predominant wear mechanisms in CA-SAG.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bacillus licheniformis, a pathogenic new strain of bacteria is considered as the main cause of high mortalities and economic losses among the ornamental fish farms of India. The present study aimed ...to investigate the anti-bacterial and Immunostimulant activity of three selected Indian medicinal plants, Allium sativum, Adhatoda vasica and Centella asiatica for treating Bacillus licheniformis PKBMS16 by subsequent experimental and clinical trials using different organic polar and non-polar solvents. The antimicrobial and Immunostimulant activity of methanolic crude extracts of Adhatoda vasica was fractions and active constituents was further characterized by chromatography and mass spectroscopy studies using FTIR, 1HNMR and 13c NMR to identify as well as to determine the nature of the pure compound which is phytol (C20H40O), a diterpene alcohol with a molecular weight of m/z 297. In order to study the in vivo anti-pathogenic influence of the biologically active compounds, phytol were incorporated to the artificial diets at the concentration of 2, 5 and 8 mg/kg and fed to the1.0 × 105 CFU/ml of Bacillus licheniformis PKBMS16 injected experimentally challenged ornamental goldfish Carassius auratus for twenty days. Phytol treated group significantly (P < 0.01 and P < 0.05) reduced the rate of fish mortality. After the termination of survivability assay the estimation of hemato-biochemical parameters have been performed and revealed the significant recovery of health condition on 20th days post treatment. Therefore, the present study concluded that the low toxicity along with high bioactivity and tolerance by lower vertebrate supports the potential of phytol as a new compound for inducing fish immunity.
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•Anti-bacterial and Immunostimulant activity of Adhatoda vasica, for treating Bacillus licheniformis PKBMS16.•The active fraction of Adhatoda vasica was characterized by chromatography and mass spectroscopy studies using FTIR, 1HNMR and 13 CNMR to identify the pure compound.•This active biological molecule is phytol (C20H40O), a diterpene alcohol with a molecular wt. of m/z 297.•Phytol (2, 5 and 8 mg/kg doses) applied to experimentally challenged Carassius auratus infected by Bacillus licheniformis PKBMS16 (1.0 × 105 CFU/ml).•Haemato-biochemical parameters revealed the significant recovery of health condition by 20th days.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The present investigation deals with the fabrication of a novel thermally sprayed coating from a diamond reinforced nano-structured bronze feedstock. Bronze powders were ball-milled with 10 wt% ...mono-crystalline diamond particles producing a micro-sized powder feedstock. The ball milled powder was agglomerated to prepare the thermal spray feedstock. Both milled and as-received powders were deposited on steel substrates using high velocity oxy-fuel spraying to produce coatings with thickness in the range of 150–200 μm. The coatings were characterized for microstructure, phases, hardness, elastic modulus and residual stress. Raman imaging of the coating revealed that diamond was retained in the coating after thermal spraying. Micro-hardness and elastic modulus of coatings improved with diamond reinforcement.
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•Diamond-reinforced nano-structured coatings were prepared from ball-milled powder feedstock.•Diamond could be retained in coatings.•Hardness and elastic modulus was increased in composite coatings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Soil organic C (SOC) pools under long-term management practices provide information on C sequestration pathways, soil quality maintenance, and crop productivity. Farmyard manure (FYM), paddy straw ...(PS), and green manure (GM) along with inorganic fertilizers were used in a 19-yr-old rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system in subtropical India to evaluate their impact on SOC stock, its different pools--total organic C (Ctot); oxidizable organic C (Coc) and its four fractions of very labile (Cfrac1), labile (Cfrac2), less labile (Cfrac3), and nonlabile C (Cfrac4); microbial biomass C (Cmic); and mineralizable C (Cmin). Cropping with only N-P-K fertilization just maintained SOC content, while N-P-K plus organics increased SOC by 24.3% over the control, their relative efficacy being FYM > PS > GM. A minimum of 3.56 Mg C ha-1 yr-1 was required to be added as organic amendments to compensate for SOC loss from cropping. The passive (Cfrac3 + Cfrac4) pool and Cmin constituted about 39 and 11.5%, respectively, of Ctot. Organics contributed toward the passive pool in the order FYM > PS > GM. Most of the pools were significantly (P = 0.005) correlated with each other. Yield and sustainable yield index were strongly related with Cfrac1, Coc, Cmic, and Cmin. Results suggest Cfrac1 as a useful indicator for assessing soil health, and balanced fertilization with FYM as suitable management for sustaining crop productivity of the rice-wheat system.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The present work develops a theoretical procedure for obtaining transport coefficients of Yukawa systems from density fluctuations. The dynamics of Yukawa systems are described in the framework of ...the generalized hydrodynamic (GH) model that incorporates strong coupling and visco-elastic memory effects by using an exponentially decaying memory function in time. A hydrodynamic matrix for such a system is exactly derived and then used to obtain an analytic expression for the density autocorrelation function (DAF)-a marker of the time dynamics of density fluctuations. The present approach is validated against a DAF obtained from numerical data of Molecular Dynamics (MD) simulations of a dusty plasma system that is a practical example of a Yukawa system. The MD results and analytic expressions derived from the model equations are then used to obtain various transport coefficients and the latter are compared with values available in the literature from other models. The influence of strong coupling and visco-elastic effects on the transport parameters are discussed. Finally, the utility of our calculations for obtaining reliable estimates of transport coefficients from experimentally determined DAF is pointed out.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The excitation and propagation of finite-amplitude low-frequency solitary waves are investigated in an argon plasma impregnated with kaolin dust particles. A nonlinear longitudinal dust acoustic ...solitary wave is excited by pulse modulating the discharge voltage with a negative potential. It is found that the velocity of the solitary wave increases and the width decreases with the increase of the modulating voltage, but the product of the solitary wave amplitude and the square of the width remains nearly constant. The experimental findings are compared with analytic soliton solutions of a model Korteveg-de Vries equation.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The use of nanofinished cermet coating has extensively increased in various industries to impede operational wear and corrosion of engineering components. In the present study, the wear and corrosion ...behaviours of the as-sprayed, ground and nanofinished coatings are investigated. The effect of compressive residual stress on the microhardness of the coatings is also evaluated. A modified model for the specific wear rate of WC-Co coating is proposed by incorporating the areal surface roughness parameter, mechanical properties and WC grain diameter. In the case of the as-sprayed and ground coatings, three-body abrasion is found as the dominant wear mechanism. The effect of three-body abrasion is found insignificant in the case of nanofinished coating. Moreover, the presence of tribofilm and tribo-oxide film reduces the wear rate of the later coating. The lower interfacial area owing to the nanoscale surface roughness and the presence of protective oxide films lead to slower corrosion for the nanofinished coating. It is perceived that surface roughness plays a significant role in wear and corrosion resistance of the coatings.
•Three body abrasions is the dominant wear mode during tribotest of rough coatings.•The presence of tribofilm in the nanofinished coating leads to a lower wear rate.•A specific wear rate model is proposed by incorporating areal surface roughness.•The hardness of the coating increases with the compressive residual stress.•The protective oxide film on the nanofinished coating leads to the lowest corrosion rate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Highly finished copper surface without any appreciable residual stress is in high demand in electronics, space, and optical industries. Conventional finishing processes are not suitable for the ...finishing of copper owing to its extremely lower hardness. In the present study, wheel based magnetorheological finishing (MRF) process is used to attain nanolevel surface roughness of oxygen-free high conductivity (OFHC) copper. The wheel speed, working gap and feed rate are selected as the main controlling process parameters. Areal surface roughness (Sa), normal force, tangential force and residual stress are studied as the response parameters. The measurement of residual stress has a significant importance as it may affect the optical properties of the finished surface. The residual stresses and phases of all the finished surfaces are analysed using X-ray diffraction (XRD) technique. A theoretical model is proposed to predict the surface roughness of the MRF processed surfaces. It is observed that a nanolevel surface roughness with lower residual stress can be attained by performing MRF with a higher working gap, and lower wheel speed and feed rate. In the present study, a minimum surface roughness (Sa) of 15.5 nm and compressive residual stress of 6.9 MPa are attained on the OFHC copper surface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In thermal spray, grit blasting is the standard method used to prepare the substrate surface before coating deposition. This study examines the effect of the grit blasting parameters on the residual ...stresses, roughness and hardness of three metal alloys with widely different mechanical properties: low-carbon steel, Ti-6Al-4V and Inconel 718. It also estimates the density of dislocations using the Williamson–Hall method. The dislocation structures of low-carbon steel grit blasted at different grit impingement angles were observed under a transmission electron microscope. The surface dislocation density was found to increase with the blasting time and angle of impact. Moreover, the depth profile of the dislocation density was in good agreement with that of the hardness profile of the blasted specimen. The residual stress depth profiles of each material at different blasting pressure showed an increase in the value and depth of maximum compressive residual stresses. Both surface residual stresses and roughness were found to increase with the grit blasting pressure, angle and, to some extent, with time and stand-off distance. The mechanisms of material erosion were found to be microcutting and indentation at lower and higher angles of abrasive impingement, respectively. The extent of damage of the materials was explained on the basis of the Johnson–Cook flow strength model.
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