Cadmium (Cd) stress is increasing at a high pace and is polluting the agricultural land. As a result, it affects animals and the human population via entering into the food chain. The aim of this work is to evaluate the possibility of amelioration of Cd stress through chitosan nanoparticles (CTS-NPs). After 15 days of sowing (DAS), Solanum lycopersicum seedlings were transplanted into maintained pots (20 in number). Cadmium (0.8 mM) was providing in the soil as CdCl2.2.5H2O at the time of transplanting; however, CTS-NPs (100 µg/mL) were given through foliar spray at 25 DAS. Data procured from the present experiment suggests that Cd toxicity considerably reduces the plant morphology, chlorophyll fluorescence, in addition to photosynthetic efficiency, antioxidant enzyme activity and protein content. However, foliar application of CTS-NPs was effective in increasing the shoot dry weight (38%), net photosynthetic rate (45%) and SPAD index (40%), while a decrease in malondialdehyde (24%) and hydrogen peroxide (20%) was observed at the 30 DAS stage as compared to control plants. On behalf of the current results, it is demonstrated that foliar treatment of CTS-NPs might be an efficient approach to ameliorate the toxic effects of Cd.

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Aim. This study aimed to compare the staining characteristics of a commercially available restorative glass ionomer cement to a formulation reinforced by the addition of carbon nanotubes and another formulation reinforced by the addition of silver nanoparticles to the powder of the same cement. Methodology. Twenty samples each of a control glass ionomer cement (PULPDENT® Glass Fill®, Pulpdent Corp. Watertown, MA, USA), control cement reinforced with 0.0006 gm (0.03% by weight) of carbon nanotubes (Sigma Aldrich, St Louis MO, USA), and control cement reinforced with 0.2 gm (10% by weight) of silver nanoparticles (Nanocyl™, Nanocyl SA, Sambreville, Belgium) were immersed in a staining solution. Color evaluations were carried out after 1 h, 24 h, and 1 week. Color change values were calculated. Results. The results indicated that carbon nanotube reinforced specimens exhibited less color stability when compared to controlled glass ionomer cement specimens; however, both samples had significantly greater color stability than silver nanoparticle reinforced glass ionomer samples. Conclusion. It can be concluded within the limitations of this study that carbon nanotube reinforced glass ionomer cements have better color stability than silver nanoparticle reinforced glass ionomer cements.

Current research introduces understanding of dental cracks with fundamental fracture behavior in natural teeth and dental materials studying of mixed mode cracks under compression-shear, tension-shear, mode I under tension, mode I under compression and mode II. The study is experimental work using models of PMMA for different cracks with different orientations. Cracking aspects of crack initiation, propagation direction, fracture distance, load and failure path are predicted experimentally and theoretically based on directional fracture approach and theories. The tests are carried out for (50) samples for compression and tension in LEFM. The friction between crack surfaces is investigated based on coefficient of friction and directional strain energy density fracture theory. The newly investigated negative critical stress intensity factor is considered for solving the complicated problems of cracks under compression loading like the occlusal stresses. The occlusal loads are compression loads with static will produce lateral tensile loads. The relations between crack orientation angle, fracture propagation angle, fracture load and fracture envelope are presented with comparisons. These results are important to predict the fracture and propagation before teeth failure. It will help for prevention and control of dental-cracks, correct restoration, prosthodontics, orthodontics, development of new technologies and new dental-materials.