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Navale Prakash M,Manamohan Maligeppagol,Asokan R.,Sharath Chandra G.,Prasad Babu K.,Latha J.,Krishna Kumar N.K.,Ellango R.,Krishna V. 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2
Helicoverpa armigera is an important pest infesting a number of crops of high commercial value leading to huge economic losses globally. RNA interference (RNAi) is a potent tool for the control of insect pests and towards this objective, transgenic tomato expressing dsRNA of Juvenile hormone acid methyl transferase (JHAMT) gene of H. armigera was developed. The H. armigera larvae fed on HaJHAMT tomato leaves led to a severe (90%) down regulation of the cognate gene expression thus adversely affected the feeding and metamorphosis. Reduction in larval and pupal weight and inability to undergo complete metamorphosis were observed that led to larval-pupal intermediates and subsequently affected the eclosion. Thus, JH down regulation is an attractive target due to specificity to insects and its important role in insect growth and development to engineer insect resistance in crops using RNAi.
Javed S. Ibrahim,M. J. N. V. Prasad,Partha Sarkar,K. Narasimhan 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2
Ultra-low carbon (ULC) steels, containing a carbon content ~ 0.055 wt%, have been used in several applications in the formof thin foils. However, there are limited studies on the effects of foil thickness (t) to grain size (d) ratio and foil condition onthe tensile response and formability of thin ULC steel foils. In the present work, the tensile and forming behaviours of ULCsteel foils of thickness about 400 μm were evaluated in both annealed and prestrained (by cold reduction to 2–7%) conditionsas a function of t/d ratio and followed by detailed texture evolution analysis. Vacuum annealing was used to achievevarying t/d ratios in the specimens. Additionally, thin ULC steel foils of 100 μm thickness in annealed condition were alsoused for examining the thickness effect. Microstructural analysis was performed using the electron backscattered diffractiontechnique. Microformability was assessed by a miniaturised Nakazima test setup with specimen geometries designed toproduce three different strain paths. The annealed foils displayed a typical yield-point phenomenon, but the total yield-pointelongation decreased with decreasing thickness and grain size. The foils exhibited typical Hall–Petch strengthening, coldwork hardening, and forming limit curves; however, there were substantial reductions in both tensile strength and ductility,and consequently, the forming strains, with decreasing the t/d ratio. The tensile response and formability of the foils wereadversely affected by both thinning and prestraining. The texture studies revealed the formation of a γ-fibre i.e., < 111 >||normaldirection, and its intensity varied significantly with the t/d ratio and mode of strain path.
Javed S. Ibrahim ,Rohit T. Mathew,M. J. N. V. Prasad,K. Narasimhan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.10
Owing to high heat flux ability and good mechanical strength, copper has been used for micro-electro-mechanical systems(MEMS) components with dimensions in micrometers processed by electrochemical methods. In the present study, finegrained copper foils of different thicknesses and grain sizes produced by pulsed electrodeposition under different controlledcurrent densities were used to investigate the effect of total number of grains across thickness of foil on its tensile responseand formability. For a comparative study, commercially available rolled Cu foils were also used. Vacuum annealing wasemployed to obtain a wide range of fully recrystallized grain sizes within same thickness of the foils. Detailed microstructuralcharacterization was carried out using scanning electron microscope attached with electron backscattered diffraction detector. The foils were subjected to uniaxial tensile testing and formability testing using a miniaturized Nakazima test setup. Asanticipated, finer the grain size higher was the yield strength. However, the strength of copper reduced with decreasing thetotal number of grains across thickness of the foil. The electrodeposited Cu foil exhibited relatively higher strength levelsbut reduced tensile ductility along with decreased strain hardening ability compared to the fully recrystallized Cu foils havingsimilar grain sizes. Furthermore, the number of grains across thickness and the prior history of foils played significantrole on the shape and trend in variation of the forming limit curve of Cu. An α-fiber (< 110 >) texture evolved in Cu duringdeformation and its volume fraction strengthened under biaxial deformation conditions.
Antoniadis, Vasileios,Levizou, Efi,Shaheen, Sabry M.,Ok, Yong Sik,Sebastian, Abin,Baum, Christel,Prasad, Majeti N.V.,Wenzel, Walter W.,Rinklebe, Jö,rg Elsevier 2017 Earth-science reviews Vol.171 No.-
<P><B>Abstract</B></P> <P>Trace elements (TEs) are deposited to soils mainly due to anthropogenic activities and pose a significant threat to human health. In this review we aimed at (a) discussing the phytoavailability of TEs as affected by various soil parameters, and by plant defense mechanisms related to uptake and translocation; (b) examining soil and plant indices related to TE phytoavailability; (c) clarifying the challenges and problems related to phytoremediation; and (d) exploring the often encountered discrepancies of lower-than-expected TE toxicity. We particularly discussed the soil-to-plant availability index (transfer coefficient, <I>TC</I>), because it encompasses all soil and plant factors related to TE phytoavailability. As for soil, we explored the effect of pH, redox potential, clay and organic matter contents, as well as aging of added elements. The latter is a key factor in interpreting the observed lower-than-expected toxicity to plants in real field conditions. This is because the discrepancy is very often generated by growth experiments that expose plants to TEs directly from TE-laden solutions or by studies that spike soils with TEs only days or weeks before planting. Also, the behavior of TEs depends on the nature and quantity of TEs. As for plant, TE absorption or exclusion is highly related to species-specific defense mechanisms developed by plants so that they are exposed to TE-induced stress. These mechanisms address TE exposure by operating both outside and inside the plant body; outside with the assistance of root exudates, and the rhizosphere microflora, and inside with selective translocation and storage processes. The absorption/exclusion behavior of plants also depends on root activities and related soil chemical processes which are highly localized within a spatial scale of a few mm from roots. Novel techniques for the imaging of TE biogeochemistry at the root-soil interface are therefore addressed and their explanatory power is demonstrated. Such plant behavior greatly affects phytoremediation, a process which also depends on the maximal TE uptake capacity of plants, especially of hyperaccumulators. However, phytoremediation also greatly depends on plant biomass yield, an important factor in determining the time required to complete the procedure. In conclusion, soil factors, as well as plant- and TE- related issues, may create discrepancies in TE phytoavailability and phytoremediation that need to be thoroughly understood and addressed.</P>