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Improving the efficiency of photosynthesis has important theoretical and practical value, and the application of pulsed light is an effective strategy for this goal. This study explored the theoretical temporal model of photosynthesis. In the experiment, the mean rate of oxygen evolution was measured under different photosynthetic photon flux densities and cycle durations with incremental pulse width modulation. The results revealed that the instantaneous oxygen evolution rate calculated using the differential method is an exponential curve, and a mathematical model was fitted. A photosynthetic capacitance model was proposed by referencing the capacitor charge circuit. The model suggests that a particular substance, which is stored in the photosynthetic capacitor, is consumed during the light period and accumulated during the dark period. This model could be used to explain the impact of the pulse parameters on the photosynthetic rate and provide new avenues for the study of photosynthesis under pulsed light to increase the photosynthetic rate. Oxygen evolution rate was measured using a new differential method. Temporal curve of photosynthetic rate was achieved by calculation. A capacitance model was proposed for photosynthesis under pulsed light. [ABSTRACT FROM AUTHOR]

Chemical crosslinking is possibly the most significant factor affecting the mechanical behavior of rubbers. In this study, we investigated the evolution of network structures (the crosslinking degree and crosslinking density) during the thermooxidative aging of a nitrile-butadiene rubber (NBR) using characterization methods such as low-dimensional NMR, solvent extraction, solvent swelling, IR spectroscopy, and mechanical property measurements. The NMR and solvent extraction results show the change of the crosslinking degree. The solvent swelling results show the change of the crosslinking density. The IR results show the chemical changes relating to crosslinking and chain scissions. Therefore, a comprehensive picture of the thermal oxidative aging of the NBR compound was drawn by the integration of various results from these methods. Crosslinking occurred throughout the aging process, whereas chain scissions took place and competed with crosslinking in the later stage. The crosslinking density increased at a nearly constant rate, whereas the increase in the crosslinking degree slowed down in the later stage. The crosslinking density was closely correlated with the hardness and Young's modulus. [ABSTRACT FROM AUTHOR]

NdhO, a regulatory oxygenic photosynthesis-specific subunit, is close to the ferredoxin-binding site of cyanobacterial NDH-1, and its levels are negatively associated with the rates of cyclic electron transfer around PSI mediated by NDH-1 (NDH-CET). However, the effect of NdhO levels on cyanobacterial cell death triggered by high temperature remains elusive. Here, our results uncovered a synergistic effect of NdhO levels on the cell death and reactive oxygen species (ROS) accumulation when cyanobacterial cells grown at 30°C for 1 day were transferred to 45°C for 2 days. Such synergistic effect was found to be closely associated with the activities of NDH-CET and CO2 assimilation during high temperature. Collectively, we propose that the effect of NdhO levels on the cyanobacterial cell bleaching and cell death triggered by high temperature is a result of influencing production of ROS by NDH-CET, which is considered to be vital to balance the ATP/NADPH ratio and improve the Calvin-Benson cycle.