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We investigate the reinforcing effects of both unmodified and surface modified nano titanium dioxide (TiO2) on the cure, mechanical, and thermal properties of natural rubber (NR) nanocomposites. The surface of nano TiO2 is modified by cationic surfactants cetyltrimethylammonium bromide (CTAB) and tetraethylammonium bromide (TEAB). The surface modification of nano TiO2 is characterized by Fourier transform infrared (FTIR) spectra and Field emission scanning electron microscopy (FESEM). The result reveals that surface modified nano TiO2 is much more efficient in improving the resulting properties of NR nanocomposites in comparison with unmodified nano TiO2. The excellent improvement in the properties of surface modified nano TiO2/NR composites is due to the better hydrophobicity and uniform dispersion of modified nano TiO2 within the NR matrix, as confirmed from morphological analysis. CTAB is much more effective than TEAB with respect to the properties of nano TiO2 based NR composites.

Sol-gel–synthesized nano zinc oxide (ZnO) is introduced as a cure activator in carbon black (CB)– and silica-filled natural rubber (NR) composites. The performance of sol-gel–synthesized nano ZnO was systematically compared with conventional ZnO for various filled NR composites in terms of cure, mechanical, aging, and thermal properties. At a filler loading level of 40 parts per hundred parts of rubber (phr), only 1 phr nano ZnO provided a better cure rate index and tensile strength as compared with 5 phr conventional ZnO in CB-filled NR composites. On the other hand, at a 40 phr filler loading level, the cure and mechanical properties of the 1 phr nano ZnO cured NR/silica composite were comparable with the properties of the 5 phr conventional ZnO cured NR/silica composite. At the same filler loading level, both 1 phr nano ZnO and 5 phr conventional ZnO had a similar effect on the thermal stability of NR/CB and NR/silica composites. As a whole, 1 phr sol-gel–based nano ZnO could be used as an efficient cure activator instead of 5 phr conventional ZnO in CB- and silica-filled NR composites with successive reduction of ZnO level.

An experiment was conducted to explore the silver-nanoparticles (Ag-NPs) and abscisic acid (ABA) to elicit sub1A quantitative trait loci (QTL) responses under submergence stress. Rice genotypes cv. Swarna and Swarna Sub1 were pre-treated with 100 mg ml−1Ag-NP [Ag-NP(+)] and 10 μM ABA [ABA(+)] at 7-day-old seedlings for 1 day in two separate sets and subsequent transfer to complete submergence for 5 days. sub1A QTL regulatory APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) expression was mitigated for both genotypes under submergence; however, retrieved with Ag-NP(+) and ABA(+) variably. ABA(+) had recorded affirmative responses than Ag-NP(+) in net assimilation rate, relative growth rate, chlorophyll content, and metal accumulation under stress. cv. Swarna Sub1 under submergence had better recovery of proline and relative water content than others. Phenolics, flavonoids, carotenoids, and lycopene content were more influenced by ABA(+) than Ag-NP(+) to recover under submergence. The development of superoxide and hydrogen peroxide had a positive and fair correlation with nicotinamide adenine dinucleotide phosphate oxidase (EC 1.6.3.1) activity under submergence. cv. Swarna Sub1 responded better under submergence through invertase (EC 3.2.1.26), starch phosphorylase (EC 2.4.1.1) and sucrose synthase (EC 2.4.1.13) activity more with ABA(+) than Ag-NP(+). The functioning of sub1A QTL for anaerobic metabolism was improved in cv. Swarna Sub1 than cv. Swarna with the support of polymorphic expression of alcohol dehydrogenase (EC 1.1.1.1). Finally, given results may arise the prospect for mitigation submergence stress by Ag-NP(+) and ABA(+) through modulation of cellular responses affiliated to sub1A QTL.