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The absence of high-efficiency oxide red phosphors restricts the development of high-performance solid-state lighting. In this work, a series of Li+ doped Sr4Al14O25:Mn4+ (SAO-Li+) red phosphors were prepared. Theoretical calculation results indicate that Li+ is inclined to occupy the gap 2 position. The low concentration Li+ gap doping has almost no influence on the Sr4Al14O25 structure, and a 0.4 mol Li+-doped sample exhibits a pure phase with regular morphology. With increasing Li+ doping content, the luminescence intensities of phosphors increase first and then decrease. 0.4 mol is found to be the optimal concentration. The fluorescence lifetime continues to decrease with the increase in the Li+ doping content and a mutation occurs at 0.5 mol Li+. Phosphor doping with Li+ can improve the thermal quenching resistance. The WLED device encapsulated with SAO-0.4Li and YAG:Ce3+ phosphors prepared showed a correlated color temperature of 4667 K, a color rendering index of 82, and a light efficiency of 137.34 lm W−1 at a driving current of 20 mA. The above results indicate that the use of a SAO-0.4Li+ phosphor is expected for application in warm WLEDs. [ABSTRACT FROM AUTHOR]

Although urbanization has deeply changed farmers' livelihoods, the improvement of their adaptation to climate change is not yet particularly clear, due to many interactive pressures and complex differences in farmers' livelihood strategies. This study uses 2-year household survey panel data from Na'Yong and Zhen'Xiong in southwest China, both of which are typically affected by meteorological disasters. First, we constructed a multi-dimensional induction of sensitivity indicators. Then, we divided farmers' livelihood strategies and identified their sensitivity levels. Finally, we extracted the typical characteristics of farmers' livelihood strategies that contribute to low sensitivity. The research shows that although non-agricultural labour can improve the income level of farmers, there is no clear positive relationship between farmers' income and their sensitivity. Levels of sensitivity depend not only on the risk of farmers with a higher exposure to the natural environment but also on the ability of farmers to disperse and avoid natural risks. Livelihood strategies with lower sensitivities have three main characteristics: diversification, marketization and ecological sustainability. This study provides a practical basis for the sustainable livelihood of farmers in the context of climate change and attempts to provide a reference for other developing countries towards the end of achieving ecological poverty alleviation. [ABSTRACT FROM AUTHOR]

The deficiency of high optical performance oxide red phosphors limits the application and development in the field of warm WLEDs. In this work a Sr4Al14O25:Mn4+ (SAO:Mn4+) series of oxide red phosphors efficiently excited by blue chips were prepared. The theoretical calculations, structure and luminescence properties were systematically studied. The results of theoretical calculation and experiments both demonstrate that Mg2+ can improve the PL intensity and thermal quenching properties of SAO:Mn4+ phosphors. Mn4+ emits red light only in the Sr4Al14O25 structure, but not in the SrAl2O4 structure. The high crystallinity pure phase of Sr4Al14O25 is obtained at 1250 °C and the impure phase of SrAl2O4 appears at 1300 °C. The optimum Mg2+ doping concentration is Mg2+/Mn4+ of 1 : 1 and maximum PL intensity appears at 0.5 mol% Mn4+. The phosphor exhibits excellent water resistance and acceptable thermal stability. Encapsulating as-prepared SAO:Mn4+,Mg2+ and commercial YAG:Ce3+ yellow phosphors, the WLED device operating with blue chips yields a low correlated color temperature of 4737 K, high color rendering index of 81.7 and luminous efficiency of 153.61 lm W−1. The above results show that the as-prepared SAO:Mn4+,Mg2+ phosphor is a potential candidate for warm WLEDs. [ABSTRACT FROM AUTHOR]

The absence of high-efficiency oxide red phosphors restricts the development of high-performance solid-state lighting. In this work, a series of Li+ doped Sr4Al14O25:Mn4+ (SAO-Li+) red phosphors were prepared. Theoretical calculation results indicate that Li+ is inclined to occupy the gap 2 position. The low concentration Li+ gap doping has almost no influence on the Sr4Al14O25 structure, and a 0.4 mol Li+-doped sample exhibits a pure phase with regular morphology. With increasing Li+ doping content, the luminescence intensities of phosphors increase first and then decrease. 0.4 mol is found to be the optimal concentration. The fluorescence lifetime continues to decrease with the increase in the Li+ doping content and a mutation occurs at 0.5 mol Li+. Phosphor doping with Li+ can improve the thermal quenching resistance. The WLED device encapsulated with SAO-0.4Li and YAG:Ce3+ phosphors prepared showed a correlated color temperature of 4667 K, a color rendering index of 82, and a light efficiency of 137.34 lm W−1 at a driving current of 20 mA. The above results indicate that the use of a SAO-0.4Li+ phosphor is expected for application in warm WLEDs. [ABSTRACT FROM AUTHOR]

The absence of high-efficiency oxide red phosphors restricts the development of high-performance solid-state lighting. In this work, a series of Li + doped Sr 4 Al 14 O 25 :Mn 4+ (SAO-Li + ) red phosphors were prepared. Theoretical calculation results indicate that Li + is inclined to occupy the gap 2 position. The low concentration Li + gap doping has almost no influence on the Sr 4 Al 14 O 25 structure, and a 0.4 mol Li + -doped sample exhibits a pure phase with regular morphology. With increasing Li + doping content, the luminescence intensities of phosphors increase first and then decrease. 0.4 mol is found to be the optimal concentration. The fluorescence lifetime continues to decrease with the increase in the Li + doping content and a mutation occurs at 0.5 mol Li + . Phosphor doping with Li + can improve the thermal quenching resistance. The WLED device encapsulated with SAO-0.4Li and YAG:Ce 3+ phosphors prepared showed a correlated color temperature of 4667 K, a color rendering index of 82, and a light efficiency of 137.34 lm W -1 at a driving current of 20 mA. The above results indicate that the use of a SAO-0.4Li + phosphor is expected for application in warm WLEDs.

In order to understand the allelopathic mechanisms of rice on weed, the allelochemical substitutes salicylic acid, p-hydroxybenzonic acid, cinnamic acid, vanillic acid and ferulic acid were used in an orthogonally gyrating regression experiment to study their interactive effects on the growth of barnyardgrass. The results indicated that whether the interactive effects between two substitutes, e.g., between salicylic and cinnamic acid or between salicylic and p-hydrobanzonic acid, were synergistic or antagonistic depended on the concentrations of each substitutes in the mixture. In the mixture of salicylic acid and p-hydrobanzonic acid, the effect of salicylic acid was synergistic at < 0.14 mmol.L(-1) but antagonistic at > 0.14 mmol.L(-1), while p-hydrobanzonic acid showed an antagonistic effect at > 0.425 mmol.L(-1). Salicylic acid at all test concentrations exhibited antagonism to cinnamic acid, while cinnamic acid had a synergistic at < 0.14 mmol.L(-1), but an antagonistic effect at >0.14 mmol.L(-1) on alicylic acid. The interactive effects between cinnamic and ferulic acid were all synergistic at test concentrations.

Allelochemical substitutions salicylic acid, p-hydroxybenzonic acid, cinnamic acid, vanillic acid and ferulic acid were tested in a gyrating regression experiment to study the weed-suppressive effect of phenolic acids on the root growth of barnyardgrass. The results showed that cinnamic acid had a significant inhibitory effect, its square item regression coefficient being -6.18; salicylic acid, p-hydroxybenzonic acid and ferulic acid had the same trend of weed-suppressive potential as cinnamic acid, while vanillic acid had a different weed-suppressive effect from the others. The inhibition rate (IR) on the root growth of barnyardgrass reached its highest level (78.5%) when 0.06 mmol x L(-1) salicylic acid, 0.60 mmol x L(-1) p-hydrobenzonic acid, 0.24 mmol x L(-1) cinnamic acid, 0.02 mmol x L(-1) vannillic acid and 0.02 mmol x L(-1) ferullic acid were mixed together to apply.