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  • Author: Zahoor Ahmad x
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Facile chemical strategy to synthesize Ag@polypyrrole microarrays and investigating its anisotropic effect on polymer conductivity

Abstract

A facile chemical approach was developed to fabricate microarrays (MAs) of Ag@polypyrrole nanocables (NCs). The strategy involved crosslinking the NCs by tetraethoxy silane (TEOS) under continuous pulse sonication without using a substrate. The material was characterized by scanning electron microscope (SEM) coupled with EDX, which revealed the longitudinal interconnections within the nanocables and creating unidirectional alignment in the form of MAs. FT-IR and Raman spectroscopy was employed to characterize the encapsulating polymer as polypyrrole (ppy) around Ag nanowires (NWs). The microarrays produced red shift in surface plasmon resonance (SPR) of Ag NWs, and drastically improved the thermal stability and conductivity of encasing ppy. It has imparted anisotropic conductivity effect on ppy which resulted in sharp decrease in resistivity from 8.35 × 1010 Ω to 2.449 Ω, when NCs were isolated and crosslinked into MAs form, respectively. The drastic decrease in resistivity of ppy was due to the anisotropic effect produced by the MAs format of NWs.

Open access
Synthesis and characterization of Ag@polycarbazole nanoparticles using different oxidants and their dispersion behavior

Abstract

Ag nanoparticles (NPs) encapsulated by polycarbazole (PCz) have been synthesized using ion adsorption method. The PCz synthesis around Ag NPs has been performed by adsorbing Ag+1 and Fe+3 oxidants onto Ag NPs, which initiated surface polymerization and thus, Ag NPs@PCz nanocomposite has been synthesized. The morphology of pure NPs and composite NPs was characterized by TEM which also elucidated the effect of oxidant on the core NPs, beside their morphologies and phase contrasts of metal NPs and polymer. The polymer around the surface of core NPs was characterized by FT-IR which proved that PCz was the organic phase of the composite NPs. UV-Vis spectroscopy has been employed to study surface plasmon resonance (SPR) of pure NPs and composite of NP which demonstrated that SPR of core NPs remained preserved after coating with the polymer. Furthermore, Zeta Sizer Nano series has been applied to analyze the dispersion behavior of pure NPs and composite NPs which displayed the greatly improved dispersion behavior of the composite NPs as compared to pure Ag NPs. Therefore, our study proved helpful to analyze the suitability of metal oxidants for PCz based nanocomposite synthesis and determination of their optical and dispersion behavior.

Open access
Nutrient Uptake and Yield of Wheat Varieties as Influenced by Foliar Potassium under Drought Condition

Abstract

Water stress experienced by a wheat crop during growth is recognized to have accumulative effect stated as a decline in total biomass over well water potential. The yield and nutrient uptake performance of two wheat (Triticum aestivum L.) varieties (Pirsabak-2013 and Atta Habib) to foliar feeding of 2% potassium (K) at three various growth phases (Zadoks GS-22, Zadoks GS-60 and Zadoks GS-73) was explored under water restricted environment in a wire house trial at the Agriculture Research Station, Harichand, Charsadda. The target was to find out the preeminent K application stage for enhancement in the drought tolerance potential. Drought stress was generated by suppression of irrigation at the three growth phases and then K was sprayed with the carboxymethyl cellulose as a sticking agent, however Tween-20 was used as a surfactant for foliar spray. Data about several agronomic characters (plant height, spike length, number of spikelets per spike, number of grains per spike, 1000-grain weight and grain yield per plant) of crop were documented via standard techniques. Moreover, at maturity, aboveground nitrogen, phosphorus, K, sodium and calcium uptakes by the crop were determined. The results point out that drought stress at all three acute growth phases unfavorably affected plant height, spike length, number of spikelets per spike, number of grains per spike, 1000-grain weight, grain yield and nutrient uptake of the wheat plant. The exogenous K application under drought stress at all three acute growth phases boosted tolerance of wheat by decreasing noxious nutrient’s uptake and augmenting the yield and yield characters. In this concerns, both varieties exposed undeviating behavior. Extreme enhancement in all the documented yield parameters and nutrients uptake was attained when K was practiced at grain filling stage of both varieties.

Open access
Metals Uptake by Wastewater Irrigated Vegetables and their Daily Dietary Intake in Peshawar, Pakistan / Pobieranie Metali Przez Warzywa Nawadniane Ściekami I Ich Dzienne Stężenie W Diecie Ludności Peszawaru, Pakistan

Abstract

Vegetables are important source of nutrients for human body. Wastewater irrigation may lead to contamination of these vegetables and cause possible health risk. In the present study impact of waste water irrigation on metals uptake (Fe, Mn, Ni, Co, Zn, Cd, Cr and Pb) by five commonly consumed vegetables (radish, cabbage, lettuce, cauliflower and spinach) grown in the suburbs of Peshawar were investigated using AAS (Atomic Absorption spectrophotometer). The uptake and accumulation of metals for vegetables irrigated with wastewater were significantly (p < 0.05) higher than tube well irrigated vegetables and permissible limits of WHO/FAO. Among the edible parts of vegetables maximum accumulation of Mn, Pb and Cd occurred in radish followed by Ni and Fe in spinach while Cr and Zn were high in cauliflower and cabbage. The estimated daily intake of metals (DIM) revealed that at present the consumption of studied vegetables were under the tolerable limits of (US-EPA, IRIS), however intake of metals in waste water irrigated vegetables were significantly high and can cause health hazards in the long run

Open access