ABSTRACT
The characteristics of TiO2 nanotube arrays (TNTs) prepared on Ti foil in sulfuric acid solution that contains Cl- under different temperatures are investigated by field emission scanning electron microscopy (FESEM), electrochemical impedance spectroscopy (EIS), Mott-Schottky measurement and Raman spectra. The solution temperature significantly affects the morphologies of TNTs, i.e., when solution temperature rises from -10 °C to 90 °C, the inner diameter of the nanotube increases and the barrier layer thickness decreases, and, as TNTs display n-type semiconductive properties, the donor density (ND) and corrosion protection decrease. Two types (types I and II) of pulse temperature are used to fabricate TNTs, in which type I is firstly anodized at a low temperature for time t, and then increases to a high temperature. While for type II, the solution temperature order is opposite to that of type I. The ND of TNTs in the case of type I is lower than ND of TNTs in the case of type II. ND decreases with the increased pulse step time for type I, while ND increases with the increased pulse step time for type II.
ABSTRACT
The stress hormone ethylene plays a key role in plant adaptation to adverse environmental conditions. Nitrogen (N) is the most quantitatively required mineral nutrient for plants, and its availability is a major determinant for crop production. Changes in N availability or N forms can alter ethylene biosynthesis and/or signaling. Ethylene serves as an important cellular signal to mediate root system architecture adaptation, N uptake and translocation, ammonium toxicity, anthocyanin accumulation, and premature senescence, thereby adapting plant growth and development to external N status. Here, we review the ethylene-mediated morphological and physiological responses and highlight how ethylene transduces the N signals to the adaptive responses. We specifically discuss the N-ethylene relations in rice, an important cereal crop in which ethylene is essential for its hypoxia survival.
