Built-up battened columns under lateral cyclic loading

Built-up members with battens designed for typical 2–2.5% of axial load may not behave satisfactorily in the presence of lateral seismic loads. Analytical evaluation of double-channel battened cantilever members designed as per the current practice, and subjected to constant axial compressive load and gradually increasing lateral load showed that the members failed to reach their expected flexural capacity due to lateral instability. The design of members was modified by changing the configuration of battens in the expected plastic-hinge region, i.e., reducing the spacing of battens in end panel by half, and designing battens for a shear demand due to moment capacity of section. The members with battens designed for moment capacity could able to reach the expected flexural strength. Five half-scale test specimens of battened members designed as per the current practice and improved design method were subjected to axial load and gradually increasing cyclic load. The specimens designed as per improved design method showed excellent performance in terms of lateral strength, lateral stiffness, moment rotation characteristics and energy dissipation capacity.     

Anthropogenic contamination and risk assessment of heavy metals in stream sediments influenced by acid mine drainage from a northeast coalfield,India

The total concentrations and chemical partitioning of heavy metals in streambed sediments, collected around the Jaintia Hills coal deposit of northeast India, were studied using pollution indices and multivariate techniques to evaluate the risk and contamination levels from heavy metals and their possible origins. Results show that sediments close to mining sites have low pH (<4), high organic carbon, and contain significant amounts of Fe-oxyhydroxide phases (mainly, goethite and schwertmannite), which implies direct impact of coal mine drainage. The average concentrations of Fe, Cu, Co, Cd, Cr, and Zn exceeded the World average, and in some cases, Cd, Cu, Ni, and Cr concentrations exceeded the threshold effects level, which suggests they will be toxic to aquatic biota. Contamination factors (CF) show that the sediments are low to highly contaminated with Cd, Cu, Mn, Pb, Fe, and Zn and low to moderately contaminated with Co, Cr and Ni. The pollution load index (PLI), degree of contamination index (C _deg) and Nemerow integrated pollution index (NIPI) show that the sediments are moderately to highly contaminated, with the extent of pollution greatest nearest to the collieries. The potential ecological risk index (RI) shows low to considerable ecological risk from heavy metals in the sediments, with Cd having the high potential of risk, which also agrees with the risk assessment code (RAC). Multivariate statistical analysis suggests that the concentrations of the heavy metals in stream sediments are strongly influenced by Fe-oxyhydroxide phases and organic carbon derived from anthropogenic sources, mainly coal mining activities. Although a significant proportion of the Cd, Mn, and Ni in the sediments are partitioned into exchangeable and organic fractions, a sizable amount of metals are also found in the Fe–Mn fraction, suggesting that Fe-oxyhydroxides play a dominant role in controlling metal mobility in these stream sediments.     

Studies on crystallization behaviour and mechanical properties of Al-Ni-La metallic glasses

Alloy ingots with nominal composition, Al_92−x Ni₈La _x (x = 4 to 6) and Al_94−x Ni₆La _x (x = 6, 7), were prepared by induction melting in a purified Ar atmosphere. Each ingot was inductively re-melted and rapidly solidified ribbons were obtained by ejecting the melt onto a rotating copper wheel in an argon atmosphere. The crystallization behaviour of melt-spun amorphous ribbon was investigated by means of differential scanning calorimetry (DSC), X-ray diffractometry and transmission electron microscopy. DSC showed that Al₈₆Ni₈La₆ alloy undergoes a three-stage and rest of the alloys undergo a two-stage crystallization process upon heating. The phases responsible for each stage of crystallization were identified. During the first crystallization stage fcc-Al precipitates for low La-containing alloys and for higher La-containing alloys a bcc metastable phase precipitates. The second crystallization stage is due to formation of intermetallic compounds along with fcc-Al. Microhardness of all the ribbons was examined at different temperatures and correlated with structural evolutions. Precipitation strengthening of nano-size fcc-Al is responsible for maximum hardness in these annealed alloys.     

Experimental study on thermal performance of optimum PG brine as a radiator coolant

The present study deals with the experimental impact of an alternative heat transfer fluids for overall performance improvement for radiators. Water and water mixed with anti‐freezing agents such as ethylene glycol (EG) and propylene glycol (PG) are the traditional coolants for an automotive radiator. Comparison of experimental and numerical analysis of optimum brine solution, that is 25% of propylene glycol and water as coolant for the rectangular fin radiator, has been well discussed. A closed loop test rig was designed, and fabricated with a wind tunnel section to achieve uniform velocity at the test section of the rectangular radiator and was tested for performance. Experimental runs were conducted at varying operating temperatures which included the runs for water, and an optimum propylene glycol brine solutions at 70 °C and 80 °C with various flow rates. Results show the energy performance of an optimum brine solution was nearly similar to that of water at high temperatures. The Nusselt number, heat transfer coefficient, and heat transfer rate for an optimum propylene glycol brine is nearly the same as water at 80 °C with a maximum deviation of 15%, 5.7%, and 6.6%, respectively, for theoretical and experimental result comparisons. Air side and coolant side pressure drops had a maximum deviation of 3.66% and 6.6%, respectively. Air and coolant exit temperatures had a deviation of 5% and 3.5%, respectively, with an air frontal velocity of 4.6 m/s in a rectangular fin radiator for an optimum brine solution used as coolant for the automotive radiator. The optimum propylene glycol brine may be environmentally beneficial.     

Performance Enhancement for Wavy Fin Automotive Radiator Using Optimum PG Brine Based Nanofluids

In this study, optimum propylene glycol (PG) brine‐based nanofluids are being proposed as coolants for a wavy finned automotive radiator. Performance analysis is conducted and compared with conventional Ethylene Glycol (EG) brine and related nanofluids. A 25% PG brine has similar heat transfer characteristics to water at higher operating temperature ranges. The effects on radiator size, weight and cost, engine efficiency and fuel consumtion, and embodied energy saving and environmental impact are discussed as well. Compared to conventional coolant(EG water brine), for the same cooling capacity and radiator size, the coolant requirement and pumping power are reduced significantly by about 25% and 64%, respectively, whereas, for the same cooling capacity and mass flow rate, the radiator size and pumping power is reduced by 4.2% and 25.5%, respectively, with PG brine‐based Ag nanofluids.Furthermore, by using optimum PG brine‐based nanofluids, 3.5% of the embodied energy may be saved, which may yield reductions in radiator cost, engine fuel consumption and environmental costs.     

Emulsifier‐free emulsion polymerization of acrylonitrile: Effect of in situ developed Cu(II)/glycine chelate complex initiated by monopersulfate

The catalytic effect of various Cu(II) salts and Cu(II) chelate complexes of certain amino acids on the emulsion polymerization of acrylonitrile in the absence of added emulsifier was investigated in experiments. The CuSO₄/glycine chelate complex was chosen for a detailed kinetic study of acrylonitrile polymerization. The polymerization was studied at varying concentrations of initiator, monomer, Cu(II), glycine, solvents, and TiO₂ over a temperature range of 30–60°C. The overall activation energy and the viscosity average molecular weight of the polymer were computed. From the kinetic and spectrophotometric studies, the mechanism of KHSO₅ decomposition by the Cu(II)/glycine complex and initiation of polymerization was suggested. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2785–2790, 1999     

Growth-dependent refractive index nonlinearity and mean microstructural properties of codeposited composite gadolinia silica films

Codeposited gadolinia silica composite films have been probed for their growth-dependent optical and microstructural properties using phase-modulated spectroscopic ellipsometry and scanning probe microscopy. The mean refractive indices were computed using an effective ellipsometric multilayer modeling approach. Most of the composite films have shown growth-induced nonlinear refractive indices to some extent. However, the mean optical properties have depicted interesting trends in the microstructural evolutions. Gadolinia silica composite films in the composition ratio ranging from 90:10 to 70:30 have depicted superior optical as well as morphological properties. Unlike conventional oxide films, these composite films displayed microstructural, spectral refractive index, and bandgap supremacy over the pure films. Such an observation cannot be explained by the empirical Moss law. Atomic force microscopy also revealed a superior morphology in the composite films. The autocorrelation and height-height correlation functional analysis have distinctly supported such superior microstructural features in the composite films, which justifies the supremacy of the optical properties. Such an observation has opened up possibilities to utilize such composite films toward deep-and extreme-ultraviolet spectral regions of the electromagnetic spectrum.     

A general approach to binary and ternary hybrid nanocrystals

We describe and demonstrate a general strategy for engineering binary and ternary hybrid nanoparticles based on spontaneous epitaxial nucleation and growth of a second and third component onto seed nanoparticles in high-temperature organic solutions. Multifunctional hybrid nanoparticles that combine magnetic, plasmonic, and semiconducting properties and that are tunable in size and morphology can be realized, as demonstrated for combinations of Au, Fe3O4 and PbS or PbSe. The properties of each component within the hybrids can be modulated strongly by the conjugating component(s) aided by the coherent interfaces between them.     

Study of the distribution of ²²⁶Ra in ground water near the uranium industry of Jharkhand, India

Ground water is the principal source of drinking water in the rural areas of India. With the aim of determining, the contribution of (226)Ra to natural background radiation through drinking water exposure pathway near an operating uranium mining industry at Jaduguda, Jharkhand state of eastern India, the (226)Ra activity concentrations were measured in potable ground water. The water analysed, both tube well and well water, was collected in areas near the uranium industry and away. The (226)Ra concentration was measured by emanometric technique. The (226)Ra level in ground water was ranging between minimum detection limit of 3.5 mBq l(-1) and a maximum of 208 mBq l(-1). The analysis of variance reveals that there is insignificant statistical variation in the median (226)Ra concentration up to a distance of >10 km from the mining complex. Variation in concentration of (226)Ra in sources is attributed to the local geochemistry and environmental factors. The (226)Ra concentration was significantly elevated in natural artesian wells in the vicinity of uranium mineralised hill and it varies from 53.4 to 754 mBq l(-1). The WHO [Guidelines for Drinking Water Quality. Third Edition, Vol. 1, Recommendation (2004)] guideline value of 1000 mBq l(-1) has not been exceeded in any of the sources investigated.     

Doping effect of polyaniline/MWCNT composites on capacitance and cyclic stability of supercapacitors

Polyaniline doped by Zn2+ ions was synthesized as nanocomposites with multiwalled carbon nanotubes (MWCNT) by in-situ oxidative polymerization and investigated as electrode material for supercapacitors. The uniform coating of polyaniline on MWCNT was characterized by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The effect of Zn2+ ions on nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy. The electrochemical performances were investigated by cyclic voltammetry (CV), constant current charging/discharging cyclic test (CC) and electrochemical impedance spectroscopy (EIS) using a three-electrode system. The doped polyaniline composites show higher specific capacitance and better cyclic stability.