Search

The present work addresses optimization of these friction stir welding process variables to maximize joint strength efficiency of welded polycarbonate sheets by using particle swarm optimization algorithm over response surface method based regression model. Initially, parametric influence on weld quality characteristics namely weld bead profile, bead geometry with associated microstructure along with micro‐hardness deviation through the weld centerline and stress‐strain behavior of the weld have been studied in detail as per full factorial design of experiments by using three different tool pin profiles such as cylindrical, square and triangular. The center point experiment i. e. tool rotational speed of 1800 min−1 and welding speed of 20 mm/min, and square tool pin profile were found to be the optimum combination with a maximum joint strength efficiency of 60.06 %. The regression model of weld ultimate tensile strength was developed by using response surface methodology which was found to be significant. Therefore, this model was further used for parametric optimization by using both response surface methodology and intelligent particle swarm optimization approaches. A slight improvement in joint strength efficiency with better optimization capability was found by using particle swarm optimization technique as compared to response surface methodology. [ABSTRACT FROM AUTHOR]

This article deals with the study of Bianchi type V cosmological model filled with perfect fluid in the context of f(R, T) gravity. R and T represent the Ricci scalar and trace of the energy–momentum tensor, respectively. The modified Einstein's field equations are solved under the consideration of hybrid exponential law for two cases of f(R, T). The presented models are shear free. [ABSTRACT FROM AUTHOR]

We report levels of polycyclic aromatic hydrocarbons in sediment, seawater, fish and crab samples from Thane creek, India. Concentrations of sixteen USEPA PAH in sediments varies from 874 to 1925 ng g −1 , dry weight (dw) in winter, between 219–495 ng g −1 in summer. In seawater Σ 16 PAHs concentration during winter was recorded 706 ± 193 ng L −1 , and during summer 337 ± 79 ng L −1 . Total concentrations of PAHs in consumable portion of lizard fish, bombay duck and crab were found 156.8 ± 18 and 122 ± 24.5 ng g −1 , 117.4 ± 17.65 ng g −1 and 95.8 ± 16.2 ng g −1 , 348 ± 94.5 and 95.62 ± 31.9 ng g −1 wet weight (ww) in summer and winter respectively. PAHs concentration were compared with sediments quality guidelines viz. ERL-ERM, TEL-PEL indexes for finding ecotoxicological risk on marine organism. The ILCR values were above public screening criteria for carcinogens. [ABSTRACT FROM AUTHOR]

The concentrations of the trace metals Mn, Zn, Cr, V, Co, Ni, Ba, Pb, Cu, Cd, As and Hg, their spatial distribution, and their correlation as a function of physico-chemical parameters were investigated for grab sediment samples collected from different locations across the Thane Creek, Mumbai, India. Hydride generation atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, and differential pulse anodic stripping voltammetry were adopted for chemical analyses. Various geochemical indices were evaluated. The studied metal/metalloids were compared with sediment quality guideline values. Besides, the role of different physico-chemical parameters of the sediments such as pH, CaCO3, cation exchange capacity, total carbon, and of the relative composition in respect to very coarse, coarse and medium sand, fine sand and very fine sand, silt and clay fraction were also critically investigated. Positive one-to-one correlations between fine sand and very fine sand, silt and clay, and total carbon with sediment metal concentrations have been noticed. Multiple regression analysis reveals strong positive correlations between sediment metal concentrations and total carbon content only. [ABSTRACT FROM AUTHOR]

We report the enhancement in the direct radiative effect due the presence of Brown carbon (BrC) as a part of organic carbon aerosols. The optical properties of organic carbon aerosols generated from pyrolytic combustion of mango tree wood ( Magnifera Indica ) and dung cake at different temperatures were considered. Mie codes were used to calculate absorption and scattering coefficients coupled with experimentally derived imaginary complex refractive index. The direct radiative effect (DRE) for sampled organic carbon aerosols was estimated using a wavelength dependent radiative transfer equation. The BrC DRE was estimated taking virtually non absorbing organic aerosols as reference. The BrC DRE from wood and dung cake was compared at different combustion temperatures and conditions. The BrC contributed positively to the direct top of the atmosphere radiative effect. Dung cake generated BrC aerosols were found to be strongly light absorbing as compared to BrC from wood combustion. It was noted that radiative effects of BrC from wood depended on its generation temperature and conditions. For BrC aerosols from dung cake such strong dependence was not observed. The average BrC aerosol DRE values were 1.53±0.76 W g −1 and 17.84±6.45 W g −1 for wood and dung cake respectively. The DRE contribution of BrC aerosols came mainly (67–90%) from visible light absorption though they exhibited strong absorption in shorter wavelengths of the UV–visible spectrum. [ABSTRACT FROM AUTHOR]

‘Nonlinear invisibility cloak’ using metamaterial is presented in this paper. To comprehend the said, the notion of point source, cylindrical source, perfect metamaterials and reduced metamaterials are taken for cloaking application. Transformation optics to the metamaterial envisages an interesting variation of both clocking shape and cloaking area with respect to aspect ratio. Simulation results revealed that both cloaking area and cloaking configuration are changed nonlinearly in case of (point source, exact metamaterial), (point source, reduced metamaterial), (cylindrical source, exact metamaterial) and (cylindrical source, reduced metamaterial). [ABSTRACT FROM AUTHOR]

In this study, size fractionated mass and 210 Po activity concentrations in mainstream cigarette smoke (MCS) were monitored for three popular cigarette brands. Size segregated collection of MCS was carried out using a cascade type impactor, while mass and 210 Po activity concentration were analyzed gravimetrically and alpha spectrometry (following the radiochemical separation) respectively. Multiple-Path Particle Dosimetry (MPPD V2.11) model is used for prediction of deposition fraction calculations for the MCS deposition in different compartment of human respiratory tract. The activity concentration of 210 Po is founds 10.56 ± 2.46 mBq per cigarette for the tested cigarette brands. 210 Po size distribution indicates most of this associates with fine fraction (Dp < 2.23 μm) of cigarette smoke. The committed annual effective dose to smokers (smoking on an average 20 cigarette a day), considering the 210 Po and 210 Pb concentrations (assuming it is in secular equilibrium with 210 Po) in MCS, was estimated between 0.22 and 0.40 mSv, with mean value of 0.30 mSv for tested cigarette brands. Considering the risk factor of fatal cancer due to radiation exposure of lung (exposure time of 30 years); the average collective estimated fatal cancer risk is estimated as 1.5 × 10 −4 due to 210 Po and 210 Pb exposure to smokers. [ABSTRACT FROM AUTHOR]

Hygrothermal effects on free vibration of woven fiber glass/epoxy laminated composite cylindrical shallow shells are investigated both numerically and experimentally. In the present finite element analysis a composite doubly curved shell model based on first order shear deformation theory (FSDT) is used for free vibration of cylindrical shell panels in hygrothermal environment. B&K FFT analyzer is used to determine the natural frequencies of vibration experimentally by conducting non-destructive testing. The effects of curvature ratios, lamination sequences and boundary conditions on natural frequencies of vibration under hygrothermal loading are investigated. The frequency of vibration decreases with increase of temperature and moisture. [ABSTRACT FROM AUTHOR]

Firewood, coal, dung cake, kerosene and Liquefied Petroleum Gas (LPG) are the most commonly used fuels for cooking and heating purposes in developing countries. Combustion of such fuels leads to high concentrations of pollutants in the indoor environment. Polycyclic aromatic hydrocarbons (PAHs) are emitted during residential combustion, and have carcinogenic and genotoxic properties. In this study, data from an experimental setup for estimation of emission rate of particulate-bound PAHs generated during combustion of such fuels are used. PAHs emission rates were used in a probabilistic single box model for prediction of time average particle associated indoor B(a)P equivalent (B(a)P eq ) concentrations of PAHs resulting from typical Indian cooking. Model parameters such as fuel consumption rate, stove power and cooking time were also evaluated experimentally. Particle bound B(a)P eq PAH emission factor was found to be highest (0.96 mg kg −1 ) for dung cake, and lowest for LPG (0.48 mg kg −1 ) among tested fuels. The time averaged B(a)P equivalent concentrations in indoor environment were found to be 0.82, 0.45, 0.87, 0.30, and 0.14 μg m −3 for firewood, coal, dung cake, kerosene and LPG respectively. Results reveal that there was higher B(a)P equivalent concentration during combustion of biomass (dung cake, fire wood) as compared to fossil fuels (coal) and non-solid fuels (kerosene, LPG). Predicted time averaged indoor air B(a)P eq concentrations of PAHs were found to be much higher than the WHO indoor air guideline values for all tested fuels. [ABSTRACT FROM AUTHOR]

The present study deals with numerical and experimental investigations on free vibration behavior of woven fiber Glass/Epoxy laminated composite shells subjected to hygrothermal environments. A composite doubly curved shell model based on first order shear deformation theory (FSDT) is considered for free vibration of shells subjected to elevated temperatures and moisture concentrations. A quadratic eight-noded isoparametric element is used for the analysis. Series of experiments is conducted to obtain natural frequencies of vibration for woven fiber Glass/Epoxy laminated composite shells using B&K FFT analyzer with PULSE software. Parametric study is carried out varying the curvature ratios, number of layers of laminate and lamination sequences on fundamental natural frequencies of laminated composite shells for different temperature and moisture concentration under different boundary conditions. The numerical and experimental results show that there is a reduction in natural frequency of laminated composite shells with the increase in temperature and moisture concentrations. [ABSTRACT FROM AUTHOR]

The present study deals with the finite element analysis of parametric instability characteristics of delaminated bidirectional Glass/Epoxy composite panels exposed to hygrothermal field with harmonic in-plane loading based on first order shear deformation theory. An 8-noded isoparametric finite element model was developed which takes account of the influences of area delamination and hygrothermal environment for predicting dynamic instability regions of composite flat panels. Validation of numerical results from finite element analysis was done with those available from previous researches. The influences of various parameters like static load factor, area of delamination, temperature, moisture, fiber orientations, boundary conditions and stacking sequence on the dynamic instability regions of bidirectional Glass/Epoxy flat panels were investigated. Significant effects of these parameters on the dynamic stability characteristics of composite plates were observed and discussed. [ABSTRACT FROM AUTHOR]

In recent years, India developed the world's 2nd largest telecom network based largely on mobile phone connections. The energy demand of the telecom sector especially in rural areas is mainly fueled by diesel combustion in mid-size generators due to either lack of grid power or unstable provision of electricity. This study quantifies the magnitude of emissions from the Indian telecom sector and presents a gridded inventory for the year 2011 with a spatial distribution derived on the provincial level including information on urban versus rural telecom installations. The estimated total NO x , PM, CO, BC, SO 2, HC and CO 2 emissions are found to be 295 ± 196 Gg/yr, 155 ± 108 Gg/yr, 61 ± 41 Gg/yr, 28 ± 18 Gg/yr, 114 ± 12 Gg/yr 19.50 ± 13 Gg/yr and 27.9 ± 12 million tons/yr, respectively. The future development of emissions from this sector will depend on the rate of electrification and possible market saturation. Air quality in rural areas of India could be improved by replacing diesel generators with renewable energy sources or electricity from the grid. [ABSTRACT FROM AUTHOR]

The convective heat transfer characteristics of Al 2 O 3 /water and CNT/water nanofluids through uniformly heated horizontal circular tube in transition regime with helical twisted tape inserts are estimated experimentally. Tests were performed with varied range of particle volume concentration (0.15%, 0.45%, 0.60% and 1%) and helical tape inserts of twist ratio (TR) = 1.5, 2.5 and 3. It is observed that the heat transfer performance of both the nanofluids increases with the increase in the particle volume fraction. The CNT/water nanofluids with helical screw tape inserts exhibits higher thermal performance compared to Al 2 O 3 /water nanofluid. The maximum enhancement in heat transfer was obtained by using CNT/water nanofluid ( ϕ = 1%) with helical tape inserts of twist ratio 1.5. For all the twist ratio of helical screw tape inserts the pressure drop for Al 2 O 3 nanofluid with helical screw tape inserts is higher compared to the CNT nanofluid. [ABSTRACT FROM AUTHOR]

In this study the momentum and energy equations are solved to analyze the flow between two parallel plates by employing second-order velocity slip and temperature jump conditions. The flow is considered to be laminar, incompressible, hydrodynamically/thermally fully developed, and steady state. In addition to the isoflux condition, viscous dissipation is included in the analysis. Closed form expressions for the temperature field and Nusselt number are obtained as a function of the Knudsen number and Brinkman number. The Nusselt number obtained by employing the second-order model is found to be lower compared to the continuum value and agrees well with the other theoretical models. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (). DOI 10.1002/htj.21116 [ABSTRACT FROM AUTHOR]

Coal fired thermal power contributes 70% of power in India. Coal fired power generation results in huge amounts of fly ash and bottom ash of varying properties. Coal, which contains the naturally occurring radionuclides, on burning results in enrichment of these radionuclides in the ashes. In the present study, coal, bottom ash and fly ash samples collected from six coal-fired power plants in India were measured for 210 Po using alpha spectrometry and for natural U, 226 Ra, 232 Th and 40 K by an HPGe γ-ray spectrometer. 210 Po in fly ash ranged from 25.7 to 70 Bq/kg with a mean value of 40.5 Bq/kg. The range and mean activities of 238 U, 226 Ra, 232 Th, 40 K in fly ash were 38.5–101 (78.1), 60–105.7 (79), 20–125 (61.7) and 43.6–200 (100) Bq/kg respectively. Fly ash and bottom ash contains two to five times more natural radionuclides than feed coal. The results were compared with the available data from earlier studies in other countries. The effect of particle size on enrichment factor of the nuclides in fly ash was studied. 210 Po showed the largest size dependence with its concentration favoring the smaller particle size while 232 Th showed least size dependence. 238 U and 226 Ra showed behavior intermediate to that of 210 Po and 232 Th. Also the correlation between sulfur content of the feed coal and activity of 210 Po was investigated. Increased sulfur content in feed coal enhanced enrichment of 210 Po in ash. [ABSTRACT FROM AUTHOR]

Abstract: A total of 18 elements viz. Si, Al, Fe, Ca, Mg, K, Na, Sr, V, Zn, Mn, Cr, Cu, Pb, Ni, Co, As and Cd were analyzed in coal, fly ash and bottom ash samples collected across India using an EDXRF technique. Various indices such as element enrichment ratio, enrichment factor (with respect to crustal average) and mineral composition were calculated. Around 95% of mass was reconstructed using the concentration of elements in this study for fly and bottom ash. [Copyright &y& Elsevier]

Abstract: The present study deals with the effects of moist environment on the natural frequencies of vibration of Glass/Epoxy woven fibre composite doubly curved panels with strip delamination using the finite element method (FEM). For modelling the delamination, multipoint constraint algorithm is incorporated in the analysis. The effects of boundary condition, delamination size and shape of panels on natural frequencies of vibration are investigated in the moisture content range. The frequencies of vibration reduce with increase of moisture in delaminated curved panels. The reductions of frequencies are more prominent for higher degree of moisture concentrations and significantly affected by boundary conditions. [Copyright &y& Elsevier]

Abstract: Distribution and enrichment of elements in sediment are influenced by their texture, mineralogical composition, and physical transport. The vertical concentration profiles of sixteen elements in core sediment samples, namely Na, Mg, Al, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sr, and Pb were measured using the energy dispersive X-ray fluorescence (EDXRF) technique. To check the anthropogenic input various indices (enrichment factor, contamination factor, index of geoaccumulation and pollution load index) were calculated and compared. [Copyright &y& Elsevier]

Air quality is a strong health driver, its accurate assessment and forecast are important in densely populated megacities to take preventive steps. We describe the first Indian operational air quality framework, SAFAR (System of Air Quality and Weather Forecasting And Research), meant for decision-makers and a research tool with a capability of three days advance forecast in four Indian megacities of distinct environment and topography. The framework includes six different components from observations and modelling to outreach. To evaluate the performance of the forecast, we focus on particulate pollutants which largely define air quality of Indian metropolis. The model prediction skill is tested for the pilot year 2019-20 which is found to be reasonable. The Normalized Gross error of PM 2.5 for Delhi is found to be highest (35%) whereas for other cities it is ∼13–20%. The Model Output Statistics (MOS) application enhanced operational forecast ability of numerical model which resulted in improving the accuracy for specific seasons (winter). [Display omitted] • Indian air quality forecasting framework for divergent environment developed. • Performance of the model found reasonable against observations. • Normalized Gross error (NGE) of PM 2.5 for Delhi is found to be highest (35%). • The NGE for Mumbai, Ahmedabad and Pune are found ∼13–20%. • Good prediction skills for weather parameters driving air quality also developed. [ABSTRACT FROM AUTHOR]

Abstract: The present study deals with numerical and experimental investigations on free vibration behavior of woven fiber Glass/Epoxy delaminated composite plates subjected to elevated temperatures and moistures. A composite plate model based on first order shear deformation theory (FSDT) with provision of mid plane square delamination is considered for free vibration of delaminated composite plates subjected to hygrothermal loading. An eight noded quadratic isoparametric element with five degrees of freedom per node is used in the formulation. A series of experiments is conducted to obtain natural frequencies of vibration for woven fiber Glass/Epoxy delaminated composite plates using B&K FFT analyzer with PULSE software, which agree reasonably well with the numerical values. Teflon film is embedded in the laminate, simulating the presence of delamination. The effects of temperature, moisture, delamination size and different boundary conditions on the natural frequencies of composite plates are investigated. The results indicate that the vibration behavior is greatly influenced by the delamination and hygrothermal parameters involved in the study. [Copyright &y& Elsevier]

Abstract: Combustion of household fuels is the major source of polycyclic aromatic hydrocarbons (PAHs) in indoor environment. The quantity and quality of PAHs in indoor environment depend on the choice of household fuels and combustion conditions (ventilation, stove type, moisture content of fuel, etc.). In present study, the mass size distribution of combustion aerosol and size fractionated PAHs (sixteen) was evaluated for most commonly used household fuels viz. firewood, coal, dung cake, kerosene and LPG. Variable configuration cascade impactor (VCCI) was used for aerosol collection, and subsequent analysis of PAHs was carried out using high performance liquid chromatography (HPLC) coupled with UV detector. For solid fuels (firewood, coal, dung cake) mass concentration was found maximum in accumulation mode i.e., size range 0.75–2.23μm. The kerosene and LPG generated aerosols were found to be distributed all over the measured size bin (>21 to <0.1μm). It was found that most of the PAHs are associated with 0.75–1.13μm size range of particle for combustion aerosols. Firewood, coal and kerosene emit maximum PAHs associated with fine fraction, while PAH content for LPG was found to be more or less same in all size fractions. Solid biomass generates more higher molecular weight (five or more rings) PAHs compared to non-solid fuels such as kerosene and LPG, while the latter are mainly emitting two and three ring PAHs. The formation of multiple ring PAHs is a function of combustion temperature which may vary according to fuel type and methods of combustion. Data of PAH contents in different size fraction of tested fuels can be used for PAH markers. [Copyright &y& Elsevier]

Abstract: Free vibration response of laminated composite shells with delamination is presented using the finite element method based on first order shear deformation theory. The shell theory used is the extension of dynamic, shear deformable theory according to the Sanders'' first approximation for doubly curved shells, which can be reduced to Love''s and Donnell''s theories by means of tracers. An eight-noded C 0 continuity, isoparametric quadrilateral element with five degrees of freedom per node is used in the formulation. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code. The natural frequencies of the delaminated cylindrical (CYL), spherical (SPH) and hyperbolic paraboloid (HYP) shells are determined by using the above mentioned shell theories, namely Sanders'', Love''s, and Donnell''s. The validity of the present approach is established by comparing the authors'' results with those available in the literature. Additional studies on free vibration response of CYL, SPH and HYP shells are conducted to assess the effects of delamination size and number of layers considering all three shell theories. It is shown that shell theories according to Sanders and Love always predict practically identical frequencies. Donnell''s theory gives reliable results only for shallow shells. Moreover, the natural frequency is found to be very sensitive to delamination size and number of layers in the shell. [Copyright &y& Elsevier]

Abstract: This article deals with the analysis of transient one-dimensional heat conduction in both Cartesian and cylindrical geometry by employing the polynomial approximation method (PAM). Four different models such as specified heat flux for both slab and tube and heat generation in both slab and tube have been analyzed. The transient temperature is found to depend on various model parameters, namely, Biot number, heat source parameter and time. With the use of PAM, it has been possible to derive a unified relation for the transient thermal behavior of solid (slab and tube) with both internal generation and boundary heat flux. Present prediction is found to be in good agreement with other analytical results reported in the literature. [Copyright &y& Elsevier]

Abstract: The effects of two different oxidizing agents viz. ferric chloride and ammonium persulfate on the purification of metallurgical grade silicon (MGSi) by leaching with hydrochloric acid were investigated as a function of temperature, particle size and hydrochloric acid concentration. It was found that the addition of oxidizing agent improved the extraction of impurities from the MGSi as compared to that in the absence of any oxidizing agent. The extraction of impurities from the MGSi increased with a decrease in particle size and increase in temperature and hydrochloric acid concentration. By leaching MGSi with 10M hydrochloric acid in the presence of 0.1M ferric chloride and at 90°C a maximum of 66% Ca, 92% Cr, 27% Fe, 98% Cu, 98% Ni and 89% Zn were removed. The unleachable Si-Fe and Si-Fe-Ti phases in the grain boundaries of MGSi hindered the extraction of Fe and Ti. [Copyright &y& Elsevier]

Abstract: The typical copper recovery from medium temperature pressure leaching of chalcopyrite concentrates, such as from the CESL process, is 95–99%. In order to examine the modes of copper loss to residue, a variety of CESL process residue samples were examined by chemical analysis, Quantitative X-Ray Diffraction (QXRD), Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDX) and Electron microprobe analysis. The SEM and QXRD analyses indicated the presence of hematite and elemental sulfur as the major phases in the residue samples. Other phases present in minor to significant quantity were jarosite, pyrite, gypsum and anhydrite. Poor agreement between total chemical analyses of the residues by ICP-MS and those calculated from QXRD indicated the presence of an amorphous phase (ferrihydrite) in the residues. The amount of ferrihydrite and crystalline iron oxyhydroxide, and association of copper with these phases were determined by a sequential extraction method. There was a five-fold increase in the amount of copper associated with amorphous iron phases as compared to the crystalline phases. [Copyright &y& Elsevier]

The present study involves extensive experimental works to investigate the hygrothermal effects on the mechanical behavior of glass:epoxy and glass:polyester composites. Static tests involving three points bend tests and subsequent interpolation of statistical parameters including interlaminar shear strength (ILSS) appears to be of significant importance for evaluation of static capacity of composite structures in hygrothermal environment. The present investigation deals with the failure behavior of woven fiber composites under different loading speeds and change in material percentage constituents under hygrothermal conditions. The investigations were carried out on different types of composites with different constituents of their weight fractions 55:45, 60:40, and 65:35 at a constant speed of 200 mm/min in hygrothermal environment and different exposure time. The statistical interpretation of ILSS indicates good quality control of specimens. The study concludes that the ILSS of composite specimens are significantly affected by temperature, moisture concentrations, increase in loading speed, and time of exposure. [ABSTRACT FROM AUTHOR]

Abstract: An experimental investigation on rewetting has been carried out by injecting water from the top of a hot vertical heater. Tests have been performed with varied range of experimental conditions (200–500°C surface temperatures, constant water flow rates 5.77–30.98gs−1). Effect of several coolant injection systems on the hydrodynamics of rewetting has been studied. It is observed that for a particular range of flow rate and initial wall temperature (21.58gs−1, 300°C) a circumferentially symmetric wet front is observed for the region closer to the coolant injection point even while using sub-cooled water. Rewetting velocity has been calculated from the temperature transients measured during the experiment and was found to vary within 1.0–20.0cms−1. Two different rewetting models () have been used to compare the present experimental data and the comparison is found to be fairly good in both the cases. It has been observed that the flow rate varies linearly with effective Biot number (M) and varies inversely with magnitude of precursory cooling (N) in the present investigation. [Copyright &y& Elsevier]

Abstract: Details of the research and development work carried out in India using SX for the treatment of the leach/waste solutions and effluents containing base metals are reviewed, focusing on solutions obtained from low-grade or complex ores, secondary resources or industrial wastes. Commercially available organic extractants, such as hydroxyl-oximes, hydroxyl-quinoline, tertiary amines, substituted phosphoric acid and other phosphate based extractants, have been used for the recovery of metals from acidic, alkaline and mixed sulfate–chloride solutions containing copper, nickel, cobalt, zinc and associated metals. The applicability of commercially available tailor-made extractants is described for the purification and enrichment of the metal contents of lean and complex solutions in an Indian context. Research efforts for the separation and recovery of valuable metals by SX are also highlighted. Treatment of solutions for producing metals by crystallization or electrowinning is described. [Copyright &y& Elsevier]

Abstract: Extraction of chromium(III) from a model solution and from a tannery waste solution was studied by ion exchange using Indion 790 resin which is a macro-porous strongly acidic cation exchange resin of sulfonated polystyrene group. The resin was found to be selective for the sorption of chromium(III) in the pH range 0.5–3.5 from a model solution containing 500ppm Cr(III). Beyond pH 3.5 extraction of chromium(III) drastically decreased from 92% to 76%. Sorption of chromium(III) on Indion 790 followed the Freundlich isotherm with a high Freundlich constant value (K f =8.57) confirming strong chemical interaction of the metal ion with the resin. Desorption of chromium(III) from the loaded resin increased with the increase in concentration of eluant (5–20% H2SO4). With 20% sulfuric acid solution 89% Cr(III) was eluted in two stages. The bench scale results were also validated in continuous mode in a fixed bed column and for the recovery of chromium(III) from a tannery solution. [Copyright &y& Elsevier]

Abstract: Conduction-controlled rewetting of two-dimensional objects is analyzed by the Heat Balance Integral Method (HBIM) considering three distinct regions: a dry region ahead of wet front, the sputtering region immediately behind the wet front and a continuous film region further upstream. The HBIM yields solutions for wet front velocity, sputtering length and temperature field with respect to wet front. Employing this method, it is seen that heat transfer mechanism is dependent upon two temperature parameters. One of them characterizes the initial wall temperature while the other specifies the range of temperature for sputtering region. Additionally, the mechanism of heat transfer is found to be dependent on two Biot numbers comprising a convective heat transfer in the wet region and a boiling heat transfer in the sputtering region. The present solution exactly matches with the one-dimensional analysis of K.H. Sun, G.E. Dix, C.L. Tien [Cooling of a very hot vertical surface by falling liquid film, ASME J. Heat Transf. 96 (1974) 126–131] for low Biot numbers. Good agreement with experimental results is also observed. [Copyright &y& Elsevier]

Abstract: In recent years there has been a growing concern all over the globe about the marine pollution due to persistent organic pollutants. Sediments, which is an important component of marine environment can serve as sorbent or concentrator for various persistent organic pollutants including Polychlorinated Biphenyls (PCBs). Transport and fate of PCB congeners in sediment depends on their physicochemical characteristics. In this study, the depth profile of accumulated PCBs in Thane Creek sediments of Mumbai, India, was studied. The sediment core samples were collected using a gravity corer, processed and analysed for different PCB congeners. Analysis of PCBs in the sediment samples were carried out using gas chromatography system equipped with electron capture detector. The study on vertical distribution of PCBs in sediment could reflect the geochemical history including changes due to anthropogenic releases into the system. The surface segment shows the downward trend for these compounds, indicating slow phase out of PCBs after ban. The concentration and composition of different homologues varies at different depth. An attempt has also been made to find out the various sources of PCBs which could have contributed to these compounds by performing factor analysis over the observed concentrations of the PCB compounds in the core sediment. [Copyright &y& Elsevier]

Abstract: The distribution of immunoreactive neurons with nonphosphorylated neurofilament protein (SMI32) was studied in temporal cortical areas in normal subjects and in patients with Alzheimer''s disease (AD). SMI32 immunopositive neurons were localized mainly in cortical layers II, III, V and VI, and were medium to large-sized pyramidal neurons. Patients with AD had prominent degeneration of SMI32 positive neurons in layers III and V of Brodmann areas 38, 36, 35 and 20; in layers II and IV of the entorhinal cortex (Brodmann area 28); and hippocampal neurons. Neurofibrillary tangles (NFTs) were stained with Thioflavin-S and with an antibody (AT8) against hyperphosphorylated tau. The NFT distribution was compared to that of the neuronal cytoskeletal marker SMI32 in these temporal cortical regions. The results showed that the loss of SMI32 immunoreactivity in temporal cortical regions of AD brain is paralleled by an increase in NFTs and AT8 immunoreactivity in neurons. The SMI32 immunoreactivity was drastically reduced in the cortical layers where tangle-bearing neurons are localized. A strong SMI32 immunoreactivity was observed in numerous neurons containing NFTs by double-immunolabeling with SMI32 and AT8. However, few neurons were labeled by AT8 and SMI32. These results suggest that the development of NFTs in some neurons results from some alteration in SMI32 expression, but does not account for all, particularly, early NFT-related changes. Also, there is a clear correlation of NFTs with selective population of pyramidal neurons in the temporal cortical areas and these pyramidal cells are specifically prone to formation of paired helical filaments. Furthermore, these pyramidal neurons might represent a significant portion of the neurons of origin of long corticocortical connection, and consequently contribute to the destruction of memory-related input to the hippocampal formation. [Copyright &y& Elsevier]

Abstract: The burning of pulverized coal to produce energy for generation of electricity in thermal power plants results in huge quantity of coal ash of varying properties. In India the coal based thermal power plants have been the major source of power generation in the past and would continue for decades to come. Because of the increase in electricity production, the amount of ash produced will increase proportionally. Very few studies on characterization of organic constituents in fly ash from Indian thermal power plants have been reported in the literature. In the present study, the fly ashes generated from five thermal power stations from different parts of India were investigated regarding the elaboration of distribution pattern of persistent organic pollutants (POPs) such as PAHs and PCBs in them. The PAHs in the fly ash samples were identified and quantified using high pressure liquid chromatography (HPLC-UV) whereas the estimation of PCB congeners was carried out using gas chromatography (GC-ECD). Lower molecular weight (MW) PAHs, were found to be predominant in fly ash samples. The concentration of Benzo(a)Pyrene which is the most potent carcinogenic PAH, varied between 0.82 ng/g and 18.14 ng/g with a mean concentration of 9.02 ng/g. Among the PCB congeners, CB-77 is having higher toxicity value, the concentrations of which in the fly ash samples were in the range of 4.58 ng/g to 104.98 ng/g with a mean value of 62.53 ng/g. [Copyright &y& Elsevier]

Abstract: Previous studies suggested a relationship between severity of symptoms and the degree of neurofibrillary tangles (NFTs) clustering in different areas of the cortex in Alzheimer’s disease (AD). The posterior inferior temporal cortex or Brodmann’s area (BA 37) is involved in object naming and recognition memory. But the cellular architecture and connectivity and the NFT pathology of this cortex in AD received inadequate attention. In this report, we describe the laminar distribution and topography of NFT pathology of BA 37 in brains of AD patients by using Thionin staining for Nissl substance, Thioflavin-S staining for NFTs, and phosphorylated tau (AT8) immunohistochemistry. NFTs mostly occurred in cortical layers II, III, V and VI in the area 37 of AD brain. Moreover, NFTs appeared like a patch or in cluster pattern along the cortical layers III and V and within the columns of pyramidal cell layers. The abnormal, intensely labeled AT8 immunoreactive cells were clustered mainly in layers III and V. Based on previously published clinical correlations between cognitive abnormalities in AD and the patterns of laminar distributed NFT cluster pathology in other areas of the brain, we conclude that a similar NFT pathology that severely affected BA 37, may indicate disruption of some forms of naming and object recognition–related circuits in human AD. [Copyright &y& Elsevier]

Abstract: A two region conduction-controlled rewetting model of hot vertical surfaces with a constant wet side heat transfer coefficient and negligible heat transfer from dry side is solved by the Heat Balance Integral Method (HBIM). The HBIM yields a simple closed form solution for rewetting velocity and temperature distribution in both dry and wet regions for given Biot numbers. Using this method it has been possible to derive a unified relationship for one-dimensional object and two-dimensional slab and rod. The effect of convection is expressed by an effective Biot number whose exact value depends on the geometry and process parameters. The solutions are found to be exactly the same as reported by Duffey and Porthouse [R.B. Duffey, D.T.C Porthouse, The physics of rewetting in water reactor emergency core cooling, Nucl. Eng. Des. 25 (1973) 379–394], Thompson [T.S. Thompson, An analysis of the wet-side heat transfer coefficient during rewetting of a hot dry patch, Nucl. Eng. Des. 22 (1972) 212–224] and Sun et al. [K.H. Sun, G.E. Dix, C.L. Tien, Cooling of a very hot vertical surface by falling liquid film, ASME J. Heat Transfer 96 (1974) 126–131; K.H. Sun, G.E. Dix, C.L. Tien, Effect of precursory cooling on falling-film rewetting, ASME J. Heat Transfer 97 (1974) 360–365]. Good agreement with experimental results is also observed. [Copyright &y& Elsevier]

Abstract: Concentration levels of polycyclic aromatic hydrocarbons (PAHs) have been determined in air and water in order to estimate the magnitude and direction of gas flux across the air–water interface at the creek adjoining the Mumbai harbour, India. The range of total PAHs was found to be 4.1–30.4 ng/m3 in air and 84.3–377.5 ng/l in seawater, respectively. The lower molecular weight PAHs revealed positive values of the fluxes indicating the tendency for transfer of these contaminants from water to air. In contrast, fluxes of less volatile compounds like benzo(k)fluoranthene and benzo(a)pyrene were always from the atmosphere into the surface water of the creek at all locations and sampling periods. While the fugacity ratio ranged from 0.12 to 6.97, it was found greater than 1 for the lower molecular weight PAHs and less than 1 for higher molecular weight PAHs. The present study suggests the active transfer of lower molecular weight dissolved PAHs into the atmosphere due to volatilization and deposition of higher molecular weight gas-phase PAHs into the surface water. [Copyright &y& Elsevier]

Abstract: Multi-compartment monitoring of residue levels of OCPs in coastal marine environment of Mumbai has been studied. The concentration of total HCHs in seawater varied from 0.16 to 15.92 ng/L and concentrations of total DDT varied from 3.01 to 33.21 ng/L. The total HCH concentration in the sediment samples was in the range of 3.8 to 16.2 ng/g. γ-HCH contributed almost 55% to the total HCH. In sediment samples the DDT has higher mean concentration in comparison to its metabolite DDE and DDD. The concentration of total HCHs in different marine species varied from 0.87 to 33.73 ng/g and concentrations of total DDT varied from 0.38 to 34.1 ng/g. The variation in the β-HCH in different compartments is not significant and this could be due to the high persistence and metabolically inactive nature of this isomer. The α-HCH is found to be more dominant in fish samples whereas the γ-HCH is major contributor in the sediment samples. [Copyright &y& Elsevier]

The problem of viscous fluid distribution in Bianchi type I space-time is considered here in a new scalar tensor theory of gravitation proposed by Saez and Ballester (1986). Particular solutions of the field equations are derived assuming the viscous coefficient to be the power functions of energy density. Some physical and geometrical properties of the solutions are also discussed. [ABSTRACT FROM AUTHOR]

The concurrent rain and air sampling was conducted for thirteen rain events between the last week of May and end of June 2001. Concentration of total PAHs varied from 84.25 to 777.49 ng/l whereas that in air was in the range of 4.05 to 34.42 ng/m3. In rainwater the lower molecular weight PAHs (e.g. Phenanthrene, Fluoranthene and Pyrene) were found to be more prominent than the higher molecular weight compounds. The gas phase scavenging ratio (Wg) was found to increase with the molecular weight of the compound. The particle phase scavenging ratio (Wp) values for the more volatile PAHs were generally much higher than those for less volatile PAHs. The higher MW PAHs have Wg values equal to or larger than their Wp values. [Copyright &y& Elsevier]

A class of exact solutions of Eistein's field equations with attractive massive scalar field in LRS Bianchi type I space time is obtained. It is shown that how the dynamical importance of the scalar field and the shear change in the course of evolution. [ABSTRACT FROM AUTHOR]

The problem of perfect fluid distribution in spatially homogeneous and anisotropic Bianchi type VI0 space-time is considered in a scalar tensor theory of gravitation proposed by Saez and Ballester (1985). Exact solutions of the field equations are derived when the metric potentials are functions of cosmic time only. Some physical and geometrical properties of the solutions are also discussed. [ABSTRACT FROM AUTHOR]

Retention time measurements on reverse phase HPLC columns at isocratic conditions are used to estimate the octanol-water partition coefficient for 16 polycyclic aromatic hydrocarbons (PAHs). The log Kow values for PAHs ranged from 3.32 (napthalene) to 6.30 (Indeno(1,2,3-cd)pyrene). The estimated values obtained from the present study were in good agreement with the literature values. This is a simple and rapid method for simultaneous determination of octanol-water partition coefficients for different PAHs. [ABSTRACT FROM AUTHOR]

Cotarnine is an important organic molecule having tetrahydroisoquinoline core. Cotarnine core exhibits very important biological property. Its biological property changes by correct functionalization of core structure to form new molecules. Herein we describe the developments of chemistry of cotarnine and its derivatives in terms of property, synthesis, reactivity and biological application from scratch to complex core. This review will update the information about cotarnine chemistry and its application for synthesis of different bioactive product. Image 1 • Cotarnine skeleton in tetrahydroisoquinoline alkaloids. • Synthesis, reactivity and biological activity of cotarnine and its analog. • Chemistry of cotarnine skeleton in noscapine and noscapinoids. • Expansion and functionalization of cotarnine ring in noscapine. • Functionalization of cotarnine and chiral semi-cotarnine. [ABSTRACT FROM AUTHOR]

• A formulation for vibration of composite beam with cracks is presented. • A program is developed in MATLAB environment based on finite element method. • Natural frequencies of vibration are obtained experimentally and numerically. • Effect of boundary, location and depth of cracks on the frequencies is analyzed. Composite beams are increasingly used in aerospace, automobile, and other applications. Crack is the most common defect in structures during its service life. The cracked composite beams are subjected to dynamic loads and the vibration of the cracked beams is of technical significance to the structural integrity of systems. The objective of the present investigation is to demonstrate the vibration characteristics of a laminated composite beam (LCB) with multiple transverse cracks. Finite element method (FEM) is used for the frequency-based crack analysis in this study. A computer program is developed in MATLAB environment for numerical analysis. First-order shear deformation theory (FSDT) is adopted for the finite element analysis. Natural frequencies of vibration are computed through the eigenvalue solver. Composite specimens are fabricated using hand lay-up technique and are tested for its material constants under tensile test. Experiments are conducted using woven roving Glass/Epoxy laminated beam samples with pre-defined cracks. The obtained test results from the experimental work using FFT analyzer are validated with the numerical results obtained through MATLAB. The effects of natural frequencies with respect to the various boundary conditions, crack depth and locations are investigated to support in real applications. A fine agreement is accomplished between the numerical and test results. Both the studies showed that natural frequencies in the LCB are significantly influenced by the location and size of the cracks. The results show that natural frequencies are decreased with cracks and an increase in fiber orientation. [ABSTRACT FROM AUTHOR]

The pressure acid leach liquor of copper concentrate generated at Uranium Corporation of India Limited (UCIL), Jaduguda was processed by solvent extraction for the recovery of valuable metals such as copper, nickel and cobalt. Copper from the leach liquor was extracted with LIX 84 in kerosene. From the copper free raffinate cobalt and nickel were separated with sodium salt of Cyanex 272. A scheme was developed to simulate the counter-current extraction of copper and cobalt–nickel. [Copyright &y& Elsevier]

The carbonaceous fine particulate matters (BC and OC) are of significant concern for air quality and climate change. A high-resolution (10 × 10 km2) gridded SAFAR (System of Air Quality and Weather Forecasting And Research) emission inventory of BC-OC has been developed for 2011 and 2018 over India using bottom-up Geographical Information Systems (GIS) based statistical model with the latest activity data and updated emission factors. The emission inventory accounted for major sectors like transport, residential, industries, Thermal Power Plant (TPP), and rest (Mobile towers, Irrigation pumps, Municipal solid waste burning, Waste to energy plants, Construction, Crematorium, Incense stick, Brick kiln). The total national BC and OC emissions for the latest year, 2018 are estimated to be 1480 Gg yr−1 and 3116 Gg yr−1, respectively. The most dominant sector is found to be the transportation sector for BC with 46% share, whereas the residential sector for OC with 39% share. An overall growth of 32% and 36% is estimated in 2018 compared to 2011 for BC and OC, respectively. The highest growth during the past 8 years is found in the transport sector whereas the residential sector has recorded the lowest growth rate. The latter is mainly due to a decline in kerosene oil, and domestic wood after the government introduced the ambitious Ujjwala scheme to replace bio-fuel with LPG. This high-resolution inventory of BC-OC will be helpful to policymakers in identifying the hotspot regions and prioritizing mitigation options, thus benefitting Human health and climate. The current gridded emissions will provide much-needed input for the regional chemistry transport models. [Display omitted] • A high resolution gridded emission inventory of C-PM over India for 2011 and 2018. • 1480 Gg yr−1 (3116 Gg yr−1) emission estimated for BC (OC) during the year 2018. • 32% and 36% growth observed in the past 8 years for BC and OC, respectively. [ABSTRACT FROM AUTHOR]

The stochastic dynamic stability analysis of laminated composite curved panels under non-uniform partial edge loading is studied using finite element analysis. The system input parameters are randomized to ascertain the stochastic first buckling load and zone of resonance. Considering the effects of transverse shear deformation and rotary inertia, first order shear deformation theory is used to model the composite doubly curved shells. The stochasticity is introduced in Love's and Donnell's theory considering dynamic and shear deformable theory according to the Sander's first approximation by tracers for doubly curved laminated shells. The moving least square method is employed as a surrogate of the actual finite element model to reduce the computational cost. The results are compared with those available in the literature. Statistical results are presented to show the effects of radius of curvatures, material properties, fibre parameters, and non-uniform load parameters on the stability boundaries. [ABSTRACT FROM AUTHOR]

Data are analyzed in terms of daily average ozone, its diurnal variation and its relation with meteorological parameters like dry bulb temperature (T), wet bulb temperature (T w ), atmospheric pressure and wind speed based on measurement of these parameters at two Indian Antarctic stations (Larsemann Hills, and Maitri) during 28th Indian Scientific Expedition of Antarctica (ISEA) organized during Antarctic summer of the year 2008–09. The work has been carried out to investigate summer time ozone level and its day-to-day and diurnal variability at these coastal locations and to highlight possible mechanism of ozone production and destruction. The result of the analysis indicates that daily average ozone concentration at Larsemann Hills varied from ~ 13 and ~ 20 ppb with overall average value of ~ 16 ppb and at Maitri, it varied from ~ 16 and ~ 21 ppb with overall average value of ~ 18 ppb. Photochemistry is found to partially contribute occasionally to the surface layer ozone at both the stations. Lower concentration of ozone at Maitri during beginning of the observational days may be due to destruction of ozone through activated halogens, whereas higher ozone on latter days may be due to photochemistry and advective transport from east to south-east areas. Ozone concentration during blizzard episodes at both the stations is reduced due to slow photochemical production of ozone, its photochemical removal and removal through deposition of ozone molecules on precipitation particles. Diurnal variation of ozone at Larsemann Hills and Maitri has been found to be absent. [ABSTRACT FROM AUTHOR]

Being a powerful tool in modelling industrial and service operations, Petri net (PN) has been extremely used in different domains, but its application in safety study is limited. In this study, we model the gantry crane operations used for industrial activities using generalized stochastic PNs. The complete cycle of operations of the gantry crane is split into three parts namely inspection and loading, movement of load, and unloading of load. PN models are developed for all three parts and the whole system as well. The developed PN models have captured the safety issues through reachability tree. The hazardous states are identified and how they ultimately lead to some unwanted accidents is demonstrated. The possibility of falling of load and failure of hook, sling, attachment and hoist rope are identified. Possible suggestions based on the study are presented for redesign of the system. For example, mechanical stoppage of operations in case of loosely connected load, and warning system for use of wrong buttons is tested using modified models. [ABSTRACT FROM PUBLISHER]

The present computational study investigates on stochastic natural frequency analyses of laminated composite curved panels with cutout based on support vector regression (SVR) model. The SVR based uncertainty quantification (UQ) algorithm in conjunction with Latin hypercube sampling is developed to achieve computational efficiency. The convergence of the present algorithm for laminated composite curved panels with cutout is validated with original finite element (FE) analysis along with traditional Monte Carlo simulation (MCS). The variations of input parameters (both individual and combined cases) are studied to portray their relative effect on the output quantity of interest. The performance of the SVR based uncertainty quantification is found to be satisfactory in the domain of input variables in dealing low and high dimensional spaces. The layer-wise variability of geometric and material properties are included considering the effect of twist angle, cutout sizes and geometries (such as cylindrical, spherical, hyperbolic paraboloid and plate). The sensitivities of input parameters in terms of coefficient of variation are enumerated to project the relative importance of different random inputs on natural frequencies. Subsequently, the noise induced effects on SVR based computational algorithm are presented to map the inevitable variability in practical field of applications. [ABSTRACT FROM AUTHOR]