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A new class of metal-polymer-laminates, fabricated using wire mesh and "steel-chips" interlayer, is shown to have significantly high interface strength. A finite element model, calibrated using tensile, lap shear, and peel tests, is used to predict the deformation and failure of the laminates. Formability of the developed laminates is studied using the limiting-dome-height tests. The metal-polymer-laminates do not delaminate in any of the tests. A complete shift of forming-limit-curve towards biaxial-tension region is observed in strain-based forming limit diagram for the polymer side. Strain-path independent forming-limits are plotted in stress space, to negative the effect of non-proportional strain histories. [Display omitted] • Metal-polymer interface strength increases significantly with use of steel chips in welding. • Non-proportional strain paths occur on polymer side in limiting dome height (LDH) tests. • Delamination is not seen in any of the LDH tests. • FEA accurately predicts forming limit curves, dome height, failure location and failure mode. [ABSTRACT FROM AUTHOR]

Abstract: Spatial and temporal variations in surface water phytoplankton pigment distribution in the Bay of Bengal were studied during the spring intermonsoon (SpIM, February–April) and the commencement of the summer monsoon (CSM, May–June), using pigment and diagnostic indices. The Prokaryotic pigment index (ProkDP) was dominant at all the oceanic stations whereas the Flagellate pigment index (FlagDP) was dominant at the near coastal stations. However, during the commencement of summer monsoon, an oscillation in the dominance of ProkDP and FlagDP was observed in the central oceanic bay, whereas flagellates and diatoms were dominant at the near coastal stations. This change in pigment pattern is possibly related to the influence of rainfall. Comparison of pigment data with microscopic cell counts indicated a significant relationship between the diatom pigment index (DiatDP) and diatom abundance. However, the relationship between the dinoflagellate pigment index (DinoDP) and dinoflagellate abundance was not significant. Studies coupling pigment composition analysis with microscopic analysis of phytoplankton in natural conditions should thus be a prerequisite in establishing valid biogeochemical and ecosystem models. [Copyright &y& Elsevier]

Vacuum hot pressing of a thermoplastic core and metal skin sheets resistance welded to wire meshes is used to fabricate high interface strength metal-polymer-metal sandwich panels. The wire mesh strongly bonds with polymer core from material interlocking and it bonds with metal skin from welding. A finite element (FE) model is developed for characterizing the deformation behavior and failure of fabricated sandwich panels. While, a continuum ductile damage model is used to characterize failure of layers in stretching, a cohesive zone model is used to characterize interface failure. The FE model is validated using tensile tests, peel tests, double lap shear tests, and V-bending experiments. Good match is seen between simulations and experiments. In V-bending, spring back as well as debonding is correctly predicted. Sandwich panels fabricated in this work form an attractive alternative to adhesively bonded panels. The developed finite element model can be used for forming analysis of developed sandwich panels and for optimizing the panel architecture. [ABSTRACT FROM AUTHOR]

Wire mesh interlayers are introduced to fabricate high interface strength metal-polymer-metal sandwich panels. While resistance welding is used to join metal sheets to wire mesh at predesignated spots, vacuum hot pressing is used to infuse polymer into the wire mesh. Peel strength for fabricated sandwich panels is seen to be around 300% higher than that for adhesive joints reported in literature. Since, interface strength is achieved from welding and mechanical interlocking, it does not degrade in presence of moisture. Uni-axial tensile tests are used to characterize strength and elongation of individual layers and fabricated sandwich panels. Interface strength is characterized using peel and double lap shear tests. V-bending and stretch forming experiments are used to demonstrate formability of the developed sandwich panels. The presented method is an attractive alternative to use of adhesives for joining of metals to polymers. [ABSTRACT FROM AUTHOR]

Phytoplankton biomass (chlorophyll- a) and community structure in the water column was analyzed across various frontal regions in the Subtropical Front (STF), Sub-Antarctic Front (SAF), Polar Front-1 (PF1) and Polar Front-2 (PF2) in the Indian Ocean sector of the Southern Ocean (SO) during the austral summer (January–February) of 2013 and 2015. The surface chlorophyll- a (Chl-a) was maximum in PF1 (0.77mg m−3) followed by the SAF (0.5 mg m−3), STF (0.26 mg m−3) and PF2 (0.21 mg m−3) in 2013. The Chl-a was maximum in the SAF (0.56 mg m−3) followed by PF1 (0.32 mg m−3), PF2 (0.28 mg m−3) and STF (0.20 mg m−3) during 2015, indicating that the average surface biomass was higher in 2013. The deep chlorophyll maximum (DCM) was located at 50 m in STF and SAF for 2013 and 2015 and was found at 75 m (100 m) in PF1 (PF2) during 2013. The diagnostic pigment (DP) index indicated that diatoms in the surface and water column increased from the STF to the PF. In contrast, smaller cell community flagellates and prokaryotes decreased from the STF to PF. Diatoms consistently increased from the surface to 120 m in SAF and PF, whereas flagellates were uniformly distributed throughout the water column. Prokaryotes were consistently distributed down to the DCM level and then progressively declined towards deeper regions. The nitrate (NO 3−), phosphate (PO 4 3−) and silicate (SiO 4) increased considerably from the STF to PF through SAF. Results indicate the biomass and community variation in the frontal regions were due to the influence of physical, chemical, and biological processes under varied environmental conditions. [ABSTRACT FROM AUTHOR]

The Southern Ocean is a very dynamic ecosystem comprising many fronts and interfrontal areas. Among the fronts, the Subtropical Front (STF) is a region of eddy activity exhibiting high spatial-temporal variability. The variability of food web structure in such a dynamic system and their influence on the plankton community structure is of great interest. The present study attempts to explain the variability of microzooplankton (MZP) mediation in the planktonic food web, using multi-disciplinary data collected along the zonal sections 40° S and 43° S in the STF during the austral summer 2012. Even though both zonal sections are in the STF, significant differences in the variability of their thermohaline structures were observed due to the presence of multiple mesoscale features (viz. cyclonic and anticyclonic eddies), leading to discrete environments within the STF. Our study highlights the concept of the classical food web in productive environments (cyclonic eddies), which is governed by the duration of such dynamic events. On the contrary, in the generally less productive anticyclonic eddies, the variability of trophic level interaction varies between the periphery and core regions of the eddies. The present study reveals the biological consequences of frequent mesoscale features in terms of the variability of food web structure. It also elucidates the trophic importance of MZP in the two contrasting environments within the STF. [ABSTRACT FROM AUTHOR]

The bio-optical characteristics of southwestern tropical Indian Ocean (SWTIO) and Equatorial Indian Ocean (EIO). [Display omitted] • Contrasting biophysical and bio-optical environments were observed in SWTIO and EIO. • DCM shows biomass maxima at SWTIO and photoacclimation maxima at EIO. • Surface absorption characteristics suggested phytoplankton are in the growth phase. • Backscattering properties explained carbon fixation by phytoplankton. • CDOM in this region are from biological and photochemical sources. The bio-optical characteristics of the surface ocean play a pivotal role in radiative transfer and photosynthetic carbon fixation. To examine spatiotemporal variability of bio-optical properties in the tropical Indian Ocean, a 10-day time-series comparative study was made at one fixed and 3 variable stations in the southwestern tropical Indian Ocean (SWTIO), and 4-stations in the Equatorial Indian Ocean (EIO) during June 2014. A total of 24 hyperspectral radiometer profiles were collected along with physicochemical parameters and phytoplankton pigments analysis. A negative sea level anomaly (SLA), higher precipitation, a more stable mixed layer, and higher buoyancy frequency (N2) were observed in SWTIO compared to EIO. The deep chlorophyll maxima (DCM) in SWTIO were characterised by deep biomass maxima (DBM) whereas in the EIO it was due to deep photoacclimation maxima (DAM). The photosynthetically available radiation (PAR) profiles were obtained by integrating downwelling irradiance from 400 to 700 nm suggesting that the SWTIO had a greater abundance of optically active substances (OAS) than the EIO. Surface chlorophyll a (Chl-a) was found to have significant relationships with phytoplankton absorption coefficient (a ph (443)). Chl-a-specific phytoplankton absorption coefficients (a* ph (443)), total absorption coefficient (a t (443)), and particulate backscattering (b bp (555)) were also related to Chl-a implying that the phytoplankton was in growth/active phase. The time-series variability of the phytoplankton and changes in the photosynthetic pigments (PSP) to photoprotective pigments (PPP) ratio at SWTIO suggested phytoplankton community shift during 5th to 7th days. Microplankton percent-abundances showed distinct linear relationships with Chl-a and b bp (555) implying that carbon fixation per unit Chl-a was higher in microplankton than in nano and picoplankton at SWTIO. The in situ Chl-a, a ph (443), a dg (443), K d (490) and C ¯ pd were used to validate the various empirical algorithms available as well as the satellite-retrieved data. The MODIS and VIIRS data correlated moderately. This study would help towards improving regional optimized algorithms for OAS and provide a baseline understanding of the scale of variability of primary production and carbon flux from space. In addition, this would contribute valuable bio-optical data from an under-sampled geographical area. [ABSTRACT FROM AUTHOR]