Nanocrystalline Gadolinium Doped Ceria: Combustion Synthesis and Electrical Characterization

Twenty mol% gadolinium doped ceria powders were prepared by citrate-nitrate combustion synthesis technique. Two different sources of cerium viz. cerium nitrate and ammonium ceric nitrate were used in different oxidant-to-fuel ratios. The crystallite size of the synthesized powders ranged 5-27 nm was obtained depending on the preparation conditions with average particle size in the range 0.64-1.26 mu m. Although, the powders were found to be agglomerated in nature, these powders were highly sinter-active as they showed very high sintered density (>= 95%) when sintered at 1250 degrees C having grain size in the range of 200-500 nm. The electrical conductivity was found to depend on the temperature with two distinct regimes at a transition point of 350 degrees C. The grain boundary showed a significant role in the total conductivity with its activation energy dependent on the material preparation conditions. The activation energy of total conduction was found to be significantly low (similar to 0.5 eV) in the temperature range of 400-700 degrees C, this property is unique for application as an electrolyte for solid oxide fuel cell operating in the low temperature range. It was found that a fuel-deficient combustion reaction using cerium nitrate as the oxidant yielded the best quality powder which showed a maximum electrical conductivity of similar to 1.74 x 10(-2) S/cm at 600 degrees C

Ionic conductivity studies on neodymium doped ceria in different atmospheres

Nano-crystalline 10 and 20 mol% neodymium (Nd) doped ceria powders were prepared by gel-combustion synthesis. The single-phase nature of the nano powder has been confirmed by X-ray diffraction. These sinter-active nano powders resulted in dense products, as the sintered densities were found to be similar to 90% of theoretical densities. Ionic conductivity studies were carried out in air, hydrogen and oxygen atmospheres. The samples showed ionic conductivity of 1.3 x 10(-2) cm(-1) at 650 degrees C, and the activation energy values obtained in this system were in the range of 0.7-1.0 eV. These studies also revealed that no electronic conduction was observed, as the ionic conductivity values were almost similar in different environments

Copper Nanoparticle (CuNP) Nanochain Arrays with a Reduced Toxicity Response: A Biophysical and Biochemical Outlook on Vigna radiata

Copper deficiency or toxicity in agricultural soil circumscribes a plant’s growth and physiology, hampering photochemical and biochemical networks within the system. So far, copper sulfate (CS) has been used widely despite its toxic effect. To get around this long-standing problem, copper nanoparticles (CuNPs) have been synthesized, characterized, and tested on mung bean plants along with commercially available salt CS, to observe morphological abnormalities enforced if any. CuNPs enhanced photosynthetic activity by modulating fluorescence emission, photophosphorylation, electron transport chain (ETC), and carbon assimilatory pathway under controlled laboratory conditions, as revealed from biochemical and biophysical studies on treated isolated mung bean chloroplast. CuNPs at the recommended dose worked better than CS in plants in terms of basic morphology, pigment contents, and antioxidative activities. CuNPs showed elevated nitrogen assimilation compared to CS. At higher doses CS was found to be toxic to the plant system, whereas CuNP did not impart any toxicity to the system including morphological and/or physiological alterations. This newly synthesized polymer-encapsulated CuNPs can be utilized as nutritional amendment to balance the nutritional disparity enforced by copper imbalance

Manganese Nanoparticles: Impact on Non-nodulated Plant as a Potent Enhancer in Nitrogen Metabolism and Toxicity Study both in Vivo and in Vitro

Mung bean plants were grown under controlled conditions and supplemented with macro- and micronutrients. The objective of this study was to determine the response of manganese nanoparticles (MnNP) in nitrate uptake, assimilation, and metabolism compared with the commercially used manganese salt, manganese sulfate (MS). MnNP was modulated to affect the assimilatory process by enhancing the net flux of nitrogen assimilation through NR-NiR and GS-GOGAT pathways. This study was associated with toxicological investigation on in vitro and in vivo systems to promote MnNP as nanofertilizer and can be used as an alternative to MS. MnNP did not impart any toxicity to the mice brain mitochondria except in the partial inhibition of complex II–III activity in ETC. Therefore, mitochondrial dysfunction and neurotoxicity, which were noted by excess usage of elemental manganese, were prevented. This is the first attempt to highlight the nitrogen uptake, assimilation, and metabolism in a plant system using a nanoparticle to promote a biosafe nanomicronutrient-based crop management