China
Africa
Explore chapters and articles related to this topic
Nitric Oxide-Induced Tolerance in Plants under Adverse Environmental Conditions
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
Neidiquele M. Silveira, Amedea B. Seabra, Eduardo C. Machado, John T. Hancock, Rafael V. Ribeiro
The diversity of NO• effects on metabolic and physiological processes is due to its physicochemical properties. NO• has an unpaired electron; it can be reduced or oxidized, forming nitroxyl (NO−) or nitrosonium (NO+) ions, respectively. Each of these reactive nitrogen species is capable of interacting differently with biological molecules (Gow and Ischiropoulos, 2001). NO• can also react with atmospheric O2 producing nitrite (NO2−) (Wink et al., 1996) and other reactive nitrogen species, such as nitrogen dioxide (NO2), or with the superoxide anion (O2•−) forming peroxynitrite (ONOO−) (Radi et al., 2002). Due to its low solubility, NO• is highly mobile in cellular systems, diffusing freely through membranes and can easily vaporize (Mur et al., 2006). Thus, despite the apparent simple structure, its complex chemical characteristics in biological systems allow the formation of multiple secondary and tertiary products. However, Liu et al. (1998) concluded that biological membranes and other hydrophobic compartments of tissues are important sites for NO• disappearance and formation of NO-derived reagents, thus showing that NO• is not as diffusible by membranes.
The Direct Leaching of Nickel Sulfide Flotation Concentrates - A Historic and State-of-the-Art Review Part II: Laboratory Investigations into Pressure Leaching
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Nebeal Faris, Mark I. Pownceby, Warren J. Bruckard, Miao Chen
The process chemistry of NSC leaching has been described in detail by Anderson (2004). The chemical reactions taking place in NSC leaching are complex; however, the key species believed responsible for enhancing sulfide dissolution is the nitrosonium ion (NO+), a powerful oxidant with the NO+/NO couple having an E° value of 1.45 V at pH 0 (vs. standard hydrogen electrode, SHE) (Anderson 2004). Support for the function of NO+ being the active species in NSC leaching stems from laboratory and plant trails conducted at Sunshine Mining and Refining Company’s Kellogg operation in Idaho, USA, on the replacement of nitric acid with NaNO2 during oxygen pressure leaching of a copper-silver sulfide residue, where an improvement in silver recovery and dissolution kinetics were observed with the use of sodium nitrite (Anderson et al. 1996b; Anderson, Harrison and Krys 1996a). Anderson et al. (1996a, 1996b) postulated that the faster leaching kinetics were due to nitrous acid (HNO2) directly yielding NO+, whilst in the case of nitric acid, it undergoes a series of reactions to eventually yield NO+ via a HNO2 intermediate, resulting in an induction period during leaching. Baldwin and Van Weert (1996) also found nitrite was more effective than nitric acid and potassium nitrate in catalyzing the pressure oxidation of ferrous sulfate by oxygen gas. The role of oxygen gas in NSC leaching is to regenerate NO+ via oxidation of NO and the net result is the reaction of metal sulfides with acid and oxygen to form metal sulfates and elemental sulfur (or sulfate) (Anderson 2004).
Low voltage tunable cholesteric liquid crystal based on electrochemical process
Published in Liquid Crystals, 2022
Yaqian Zhang, Wanli He, Yongfeng Cui, Lei Zhang, Yuzhan Li, Zhou Yang, Dong Wang, Hui Cao
According to the experimental design ratio, samples were composed of certain amount of LC matrix doped with chiral dopant R5011, a string of electrochemical chiral molecules CD-Fc, and equimolar amounts of single-electron oxidant Nitrosonium Tetrafluoroborate (NOBF4). Then, 4 mL of anhydrous dichloromethane and anhydrous ethanol solvent were added, and sonicated with shaking to obtain a uniformly mixed solution. Next, centrifuge tubes were moved to a vacuum oven at 60°C to evaporate solvent under reduced pressure for 10 h. Finally, samples were poured into the non-functionalised liquid crystal cell by siphoning.