This paper reports on a scalable bottom-up technology for producing periodic gold nanotips with tunable sharpness as surface-enhanced Raman scattering (SERS) substrates. Inverted silicon pyramidal pits, which are templated from non-close-packed colloidal crystals prepared by a spin-coating technology, are used as structural templates to replicate arrays of polymer nanopyramids with nanoscale sharp tips. The deposition of a thin layer of gold on the polymer nanopyramids leads to the formation of SERS-active substrates with a high enhancement factor (up to 10(8)). The thickness of the deposited metal determines the sharpness of the nanotips and the resulting Raman enhancement factor. Finite-element electromagnetic modeling shows that the nanotips can significantly enhance the local electromagnetic field and the sharpness of nanotips greatly affects the SERS enhancement.

Morphometric analysis in the recent few years has derived attention in terms of its applicability in different aspects of geological and environmental perspectives. It provides an insight into the process driven changes such as drainage basin assessment, runoff, infiltration, basin evolution, natural and tectonic framework etc. The study of the Ghaghara River fluvial dynamics in a gentle sloping region and alluvial terrain has not been put forward in a broad perspective as compared to hilly or hard rock terrains and needs to be addressed effectively. In the present paper, the morphometric analysis of the Ghaghara River has been carried out to delineate various surface processes that carve the basin into fluvial terrain. The basin delineation has been done using Shuttle Radar Topographic Mission (SRTM) data using Arc GIS 10.3. The study shows stream varying from one to six (I-1844, II- 807, III-200, IV- 49, V-23 and VI-1) orders. The mean bifurcation ratio indicates that the basin is geologically and structurally controlled in flat regions. The low stream frequency value 0-5km−2, explains that the basin under study is highly permeable. The length of overland flow (>0.7) is indicative of sheet erosion rather than channel erosion, while the drainage texture points towards the coarse texture. The morphometric analysis and observations from the measured parameters indicate an asymmetrical and elongated basin with neo-tectonic activities. Therefore, multi-fold interpretations are generated on the basis of the morphometric analysis of the Ghaghara river basin which may be useful in providing information relevant to societal interests.

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Micromorphology has important application in earth surface process and landform studies particularly in alluvial settings such as the Indo‐Gangetic Plains (IGP) with different geomorphic surfaces to identify climatic changes and neotectonic events and their influence on pedogenesis. The soils of the IGP extending from arid upland in the west to per humid deltaic plains in the east developed on five geomorphic surfaces namely QIG1 to QIG5 originating during the last 13.5 ka. Four soil‐geomorphic systems across the entire IGP are identified as: (i) the western Yamuna Plains/Uplands, (ii) the Yamuna‐Ganga Interfluve, (iii) the Ganga‐Ghaghara Interfluve, and (iv) the Deltaic Plains. Thin section analysis of the soils across the four soil‐geomorphic systems provides a record of provenance, mineral weathering, pedogenic processes and polygenesis in IGP. The soils over major parts of the IGP dominantly contain muscovite and quartz and small fraction of highly altered feldspar derived from the Himalayas. However, soils in the western and eastern parts of the IGP contain large volumes of fresh to weakly altered plagioclase and smectitic clay derived from the Indian craton. The soils in western Yamuna Plains/Uplands dominated by QIG2–QIG3 geomorphic surfaces and pedogenic carbonate developed in semi‐arid climate prior to 5 ka. However, soils of the central part of the IGP in the Yamuna‐Ganga Interfluve and Ganga‐Ghaghara Interfluve regions with dominance of QIG4–QIG5 surfaces are polygenetic due to climate change over the last 13.5 ka. The clay pedofeatures formed during earlier wet phase (13.5–11 ka) show degradation, loss of preferred orientation, speckled appearance in contrast with the later phase of wet climate (6.5–4 ka). The soils over the deltaic plains with dominance of vertic features along with clay pedofeatures suggest that illuviation of fine clay is an important pedogenic process even in soils with shrink‐swell characteristics. Copyright © 2015 John Wiley & Sons, Ltd.

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