8 research outputs found
Modulation of SST, SSS over northern Bay of Bengal on ISO time scale
High resolution observations of atmospheric and oceanic variables are carried out at northern Bay of Bengal from 22nd July to 6th August 2009 on-board ORV Sagar kanya under the Continental Tropical Convergence Zone research/observational programme. Freshening of surface layer by more than 4 psu within 24 hours is observed, which is followed by warming in the surface layer temperature. The heat and salt budget analysis primarily indicates dominant role of advection processes on the evolution of temperature and salinity. The amount of rainfall received at observation site could not explain the observed freshening, thus an extensive analysis using wavelet coherence is done to find out the source of advected fresh water to the observed location. It is found that surface salinity in the northern Bay of Bengal (at 15 N) varies coherently with the rainfall over Ganga-Brahmaputra catchment area on intraseasonal time scale and with lag of about 60 days. Based on above observations, this study hypothesize that the intraseasonal rainfall variation modulates the amount of river discharge, which in turn modulates the salinity over northern Bay of Bengal on intraseasonal time scale. Since surface warming always follows the surface freshening, the time delay between the rainfall over catchment area and freshening at northern Bay of Bengal may explain the post monsoon warming. Importance of atmosphere-ocean coupling in driving the dynamics of the northern bay of Bengal has been clearly brought out in this study
Improved Performance of Solution-Processed n‑Type Organic Field-Effect Transistors by Regulating the Intermolecular Interactions and Crystalline Domains on Macroscopic Scale
The
development of four new n-channel naphthalene diimide (NDI)
and perylene diimide (PDI) copolymers (NDI-Ph, NDI-BT, PDI-Ph, and
PDI-BT) and their solution processed thin film transistor (TFT) devices
are reported. Remarkable enhancements in the electron transport behavior
for all the four copolymers were achieved on improving the intermolecular
interactions in their thin film structures. These solution processable
n-type copolymers having NDI and PDI backbone were synthesized in
high yields (83–86%) by palladium catalyzed Suzuki coupling
reactions, and their excellent solubility in several organic solvents
allowed their deposition in organic thin film transistor (OTFT) devices
from solution directly. Since these copolymers possess crystalline
domains, annealing their films induced crystalline phases in the thin
film structures with a very high degree of enhancement in crystallinity
that was more prominent for PDI copolymers as compared to NDI derivatives.
This resulted in significant enhancement in the intermolecular interactions
in the thin film state on the macro scale, facilitating improved and
higher charge carrier transport in annealed devices as compared to
the as-spun devices that have lesser crystalline phases. The transport
measurements performed for these four copolymers helped us to understand
the difference in transport mechanism between D–A and A–A
moiety and confirmed that tuning the thin film structures and the
electronic properties by modifying the copolymer backbone structures
as well as annealing them at appropriate temperature has profound
implications on the level of improvement in electron transport behavior.
The enhancement in μ<sub>e</sub> values for all four copolymers
is very large for any reported n-type copolymers. It is observed that
the extended conjugation in the four copolymer structures, the efficient
intermolecular interactions in the thin film state, and the formation
of crystalline domains in the copolymers after annealing are, in principle,
responsible for the enhanced device performance. These copolymers
demonstrated electron mobility enhancement of several orders and are
reported to be as high as 0.8 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> and 0.2 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> with <i>I</i><sub>on</sub>/<i>I</i><sub>off</sub> ratios 10<sup>5</sup> for NDI-Ph and NDI-BT,
while those of PDI-Ph and PDI-BT are 0.04 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> and 0.032 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>, respectively, with <i>I</i><sub>on</sub>/<i>I</i><sub>off</sub> ratios of 10<sup>3</sup>–10<sup>4</sup>
Current Research Trends and Prospects for Yield and Quality Improvement in Sesame, an Important Oilseed Crop
Climate change is shifting agricultural production, which could impact the economic and cultural contexts of the oilseed industry, including sesame. Environmental threats (biotic and abiotic stresses) affect sesame production and thus yield (especially oil content). However, few studies have investigated the genetic enhancement, quality improvement, or the underlying mechanisms of stress tolerance in sesame. This study reveals the challenges faced by farmers/researchers growing sesame crops and the potential genetic and genomic resources for addressing the threats, including: (1) developing sesame varieties that tolerate phyllody, root rot disease, and waterlogging; (2) investigating beneficial agro-morphological traits, such as determinate growth, prostrate habit, and delayed response to seed shattering; (3) using wild relatives of sesame for wide hybridization; and (4) advancing existing strategies to maintain sesame production under changing climatic conditions. Future research programs need to add technologies and develop the best research strategies for economic and sustainable development