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High temperature during early grain‐filling stage is one of the serious abiotic stresses limiting maize yield in the North China Plain. Nitrogen (N) fertiliser has an important role in promoting crop growth, especially under abiotic stresses. However, its contribution to alleviating heat stress (HS) inhibition on maize photosynthesis during early grain‐filling stage is still unclear. Experiments with three N rates (LN, low nitrogen; MN, medium nitrogen; HN, high nitrogen) and two temperature (HS, heat stress; CK, ambient temperature as control) regimes were conducted to examine the effects of increasing N supply on photosynthesis, N assimilation, antioxidant system, and hormones homeostasis of maize during early grain‐filling stage using two maize hybrids Xianyu335 (XY335, heat‐sensitive) and Zhengdan (ZD958, heat‐tolerant). HS negatively affected photosynthesis of both two hybrids, exhibited lower net photosynthetic rate, chlorophyll content and activities of Rubisco and phosphoenolpyruvate carboxylase (PEPC) compared with CK, and then decreased dry matter accumulation of maize, with a lesser extent for ZD958 than XY335. However, increasing N supply alleviated the adverse effects of HS on maize photosynthesis due to improved N assimilation capacity. Under HS condition, greater N content and higher activities of glutamine synthetase and glutamate synthase in maize ear leaf were found in treatment of HN compared with LN and MN. HN with higher N assimilation capacity directly increased the net photosynthetic rate due to improved chlorophyll content, activities of Rubisco and PEPC and antioxidant capacity. HS‐induced abscisic acid (ABA) accumulation was also repressed by HN, and then enhanced the stomatal conductance and transpiration rate to maintain higher photosynthetic capacity compared with LN and MN. Moreover, the positive effects of increasing N supply on maize photosynthesis under HS condition exhibited a larger extent for XY335 than ZD958. As a result of improved photosynthesis and N assimilation capacity by adequate N supply, maize accumulated more biomass under HS, especially for heat‐sensitive hybrid. [ABSTRACT FROM AUTHOR]

Objectives: Previous reports on aortic arch variations have emphasized on its cardiovascular significance. We present a case of a rare variation of aortic arch complicated with multiple ruptured intracranial aneurysms. Methods: This case report reviews the effects of the diameter of internal carotid artery of isolated origins on cerebral vessels. Results: The brachiocephalic trunk, left external carotid artery, left internal carotid artery, left vertebral artery, and the left subclavian artery originating from the aortic arch complicated with multiple ruptured intracranial aneurysms have not been reported. Conclusions: Variation of the aortic arch may affect carotid and cerebral vessel structures as well as blood flow and is a potential risk factor for stroke. Third aortic arch degeneration, or dorsal aorta non-degeneration, is a potential embryologic mechanism for the absence of the left common carotid artery. [ABSTRACT FROM AUTHOR]