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Soil salinity is a growing problem in agriculture, plant growth regulators (PGRs) can regulate plant response to stress. The objective of this study was to evaluate the effects of exogenous 6-benzyladenine (6-BA) on photosynthetic capacity and antioxidant defences in watermelon (Citrullus lanatus L.) seedlings under NaCl stress. Two watermelon genotypes were subjected to four different treatments: (1) normal water (control); (2) 20 mg L−1 6-BA; (3) 120 mmol L−1 NaCl; and (4) 120 mmol L−1 NaCl + 20 mg L−1 6-BA. Our results showed that NaCl stress inhibited the growth of watermelon seedlings, decreased their photosynthetic capacity, promoted membrane lipid peroxidation, and lowered the activity of protective enzymes. Additionally the salt-tolerant Charleston Gray variety fared better than the salt-sensitive Zhengzi NO.017 variety under NaCl stress. Foliar spraying of 6-BA under NaCl stress significantly increased biomass accumulation, as well as photosynthetic pigment, soluble sugar, and protein content, while decreasing malondialdehyde levels, H2O2 content, and electrolyte leakage. Moreover, 6-BA enhanced photosynthetic parameters, including net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and transpiration rate; activated antioxidant enzymes, such as superoxide dismutase, catalase, and peroxidase; and improved the efficiency of the ascorbate-glutathione cycle by stimulating glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase, as well as ascorbic acid and glutathione content. Principal component analysis confirmed that 6-BA improved salt tolerance of the two watermelon varieties, particularly Zhengzi NO.017, albeit through two different regulatory mechanisms. In conclusion, 6-BA treatment could alleviate NaCl stress-induced damage and improve salt tolerance of watermelons by regulating photosynthesis and osmoregulation, activating the ascorbate-glutathione cycle, and promoting antioxidant defences. The antioxidant and ascorbate-glutathione cycle of two types of salt-tolerant watermelon (Citrullus lanatus L.) seedlings under NaCl stress reveal an cytokinin regulated watermelon acclimation mechanism to the NaCl stress. [ABSTRACT FROM AUTHOR]

Warranties are prevalent in the market. The manufacturer of products sold with warranties often faces a problem of balancing a trade-off between warranty cost and boosted demand by warranties when designing the warranties. For a two-dimensional base warranty with both age limit and usage limit, the heterogeneous usage rate of customers not only has an effect on warranty cost but also differentiates customers’ perceptions on warranty period. For example, the high-usage customers are more concerned about the usage limit of the warranty period, while the low-usage customers are more preferred to a longer age limit. This paper defines an attractiveness index based on the available warranty region to describe the extent of attractiveness of a two-dimensional warranty period to customers with heterogeneous usage rate. Moreover, a demand function based on the attractiveness index is proposed to describe the boosted demand of extending the warranty period. From the perspective of the manufacturer, the optimal two-dimensional base warranty period is designed by maximising the expected profit considering the trade-off. Both numerical examples and a case study are presented to illustrate the application of the proposed method. [ABSTRACT FROM AUTHOR]

Design of experiments has received much attention in the context of reliability improvement. Many engineers and researchers are considering how to use designed experiments to improve the reliability of products and processes. This work illustrates a 12-run Plackett-Burman design and its analysis to improve the reliability of a diamond drill bit. A detailed description and execution of the design are provided including how to choose the factors and determine the number of experimental factors. In addition, the results of the real-world experiment are presented and the predicted performance from statistical model fitting is verified by part of a confirmation experiment. The experimental data show that the recommended factor settings substantially improved the reliability of the diamond drill bits. [ABSTRACT FROM AUTHOR]