Photodegradation of Imidacloprid Insecticide by Ag-Deposited Titanate Nanotubes: A Study of Intermediates and Their Reaction Pathways

The present work demonstrates the influence of Ag-loading (0.2–1.0 wt %) onto sodium titanate nanotubes (TNT) for complete photomineralization of the neurotoxic imidacloprid (IMI) insecticide under UV light illumination. It has been observed that degradation of IMI follows pseudo-first-order kinetics, where 0.5 wt % Ag-loaded TNT exhibited highest apparent rate constant (2.2 × 10^–2 min^–1) and corresponding least half-life (<i>t</i>_1/2) of 31 min for IMI relative to bare P25-TiO₂ (3.4 × 10^–3 min^–1, <i>t</i>_1/2 = 230 min). The mineralization of IMI intermediates to CO₂ during its photooxidation has been described by time course GC-MS and GC analysis and has been correlated with the kinetic analysis. The investigation for the role and quantitative estimation of the fate of heteroatoms (N, O, and Cl) present in IMI revealed an increase in the amount of nitrate, nitrite, and chloride ions with time during its photooxidation. On the basis of these results a mechanistic pathway for photomineralization of IMI is proposed

Influence of Thermal Treatment and Fe-Loading on Morphology, Crystal Structure, and Photocatalytic Activity of Sodium Titanate Nanotubes

<div><p>An understanding of collective influence of Fe-loading and calcination on changes in the crystal structure, morphology, phase composition, and photocatalytic activity of titanate-nanostructures is investigated here. Bare sodium-titanate nanotubes (TNT) having a BET-surface-area (<i>S</i>_BET) of 176 m² g⁻¹ were transformed to sodium-titanate nanorods (TNT(S)) of <i>S</i>_BET = 21 m² g⁻¹ when calcined at 800°C. Whereas, calcination of Fe-loaded-TNT at 800°C led to a variety of fragmented particles having different crystal structures, <i>S</i>_BET (21–39 m² g⁻¹), shape, and sizes (50–70 nm) attributed to the strain induced thermal-decomposition of TNT after Fe-loading. The comparative photocatalytic activity of as-prepared catalysts under UV-light irradiation was evaluated by photooxidation of naphthalene to CO₂, with the identification of its photoproduced intermediates by GC-MS analysis. These results are well explained in correlation with the surface area, size, and shape of as-prepared catalysts.</p></div

Selection of housekeeping genes and demonstration of RNAi in cotton leafhopper, <i>Amrasca biguttula biguttula</i> (Ishida) - Fig 6

<p>Expression of candidate genes in A. <i>biguttula biguttula</i> fed with dsRNA containing liquid diet by membrane feeding assay (A) Abb IAP (Inhibitor of Apoptosis) knockdown, (B) Abb AQP (Aquaporin) knockdown, (C) VATPase knockdown, (D) Snf7 (Multivesicular protein) knockdown. The mRNA levels of each gene have been normalized with ribosomal protein (RP13) as a reference gene. The error bars represent the standard deviation (n = 3) and * represents significant differences in mRNA levels compared to that in control—fed on dsGFP (P ≤ 0.05, Student’s t-test).</p

Corrected percent mortality in the leafhopper nymphs at 48h after dsRNA feeding.

<p>Corrected percent mortality in the leafhopper nymphs at 48h after dsRNA feeding.</p

Annotation of different target genes of cotton leafhopper from RNA sequence data using BlastoGo software and primers used for expression analysis of housekeeping genes.

<p>Annotation of different target genes of cotton leafhopper from RNA sequence data using BlastoGo software and primers used for expression analysis of housekeeping genes.</p

Stability values of all candidate reference genes estimated by Normfinder across all developmental stages and starvation stress.

<p>Stability values of all candidate reference genes estimated by Normfinder across all developmental stages and starvation stress.</p

Synthetic diet composition for delivery of dsRNA in cotton leafhopper through membrane feeding.

<p>Synthetic diet composition for delivery of dsRNA in cotton leafhopper through membrane feeding.</p

Visualization of different dsRNA on 1% agarose gel.

<p>The dsRNA was synthesized for RNAi studies in cotton leafhopper using diet bioassay.</p

Ranking of housekeeping genes in cotton leafhopper based on geometric mean using RefFinder software.

<p>Ranking of housekeeping genes in cotton leafhopper based on geometric mean using RefFinder software.</p

Primer sequences and amplicon characteristics of the candidate reference genes.

<p>Primer sequences and amplicon characteristics of the candidate reference genes.</p