Cold acclimation improves photosynthesis by regulating the ascorbate–glutathione cycle in chloroplasts of Kandelia obovata

As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to determine the resistance of K. obovata seedlings to low temperature stress by cold acclimation and to explain the mechanisms for alleviating cold injury. To understand these mechanisms, seedlings that were acclimatized and not acclimatized were exposed to 5℃/- 2℃(day/night)for 48 h.Results showed that low temperature stress reduced leaf photosynthesis of non-acclimatized seedlings by inducing oxidative stress and structural damage to chloroplasts. These phenomena were shown by increasing levels of malondialdehyde (MDA), O2-and H2O2, as well as decreasing enzyme activities in the ascorbate–glutathione (AsA-GSH) cycle. However, cold-acclimatized seedlings had improved photosynthetic rates and efficiency of photosystem II (PSII) under low temperature stress. Compared with non-acclimatized seedlings, leaves of coldacclimatized seedlings under low temperature stress for 48 h exhibited higher anti-oxidative enzyme activities, lower levels of O2^- and H2O2, less damage to chloroplast structure, and removed 33.7% of MDA at low temperature stress for 48 h. The data indicate that cold acclimation enhances photosynthetic capacity by effectively regulating activation in the PSII electron transport and the AsA–GSH cycle to scavenge excess ROS in chloroplasts, while the latter is more important.

A Hyper-Heuristic Framework for Lifetime Maximization in Wireless Sensor Networks With A Mobile Sink

Maximizing the lifetime of wireless sensor networks(WSNs) is an important and challenging research problem. Properly scheduling the movements of mobile sinks to balance the energy consumption of wireless sensor network is one of the most effective approaches to prolong the lifetime of wireless sensor networks. However, the existing mobile sink scheduling methods either require a great amount of computational time or lack effectiveness in finding high-quality scheduling solutions. To address the above issues, this paper proposes a novel hyperheuristic framework, which can automatically construct high-level heuristics to schedule the sink movements and prolong the network lifetime. In the proposed framework, a set of low-level heuristics are defined as building blocks to construct high-level heuristics and a set of random networks with different features are designed for training. Further, a genetic programming algorithm is adopted to automatically evolve promising high-level heuristics based on the building blocks and the training networks. By using the genetic programming to evolve more effective heuristics and applying these heuristics in a greedy scheme, our proposed hyper-heuristic framework can prolong the network lifetime competitively with other methods, with small time consumption. A series of comprehensive experiments, including both static and dynamic networks,are designed. The simulation results have demonstrated that the proposed method can offer a very promising performance in terms of network lifetime and response time.

Direct Electrochemical Synthesis of Sulfur-Containing Triazolium Inner Salts

Main observation and conclusion The electrochemical thiocyanation/cyclization of aldehyde hydrazones was developed under external oxidant-free and catalyst-free conditions.In contrast to previous thiocyanation,this electrosynthetic approach enabled a cascade C-H thiocyanation/cyclization through a mild,direct electrolysis manner in an undivided cell without the additive of halogens and stoichiometric oxidants.In this protocol,commercially available and inexpensive sodium thiocyanate was used,which played a dual role as a thiocyanation reagent and electrolyte.This strategy provides expedient access to functionalized sulfur-containing triazolium inner salts with ample scope and diverse functional group tolerance.Based on the findings of mechanistic studies,a reaction mechanism was proposed.

Late-stage azolation of benzylic C‒H bonds enabled by electrooxidation

The installation of azoles via C–H/N–H cross-coupling is significantly underdeveloped,particularly in benzylic C–H azolation due to the requirement for external chemical oxidants and the challenge in controlling the site-and chemo-selectivity.Herein,a late-stage azolation of benzylic C‒H bonds enabled by electrooxidation is described,which proceeds in an undivided cell under mild,catalyst-and chemical-oxidant-free reaction conditions.The strategy empowers the C‒H azolation on primary,secondary,and even challenging tertiary benzylic positions selectively.The remarkable synthetic utility of our approach is highlighted by its easy scalability without overoxidation of products and ample scope with valuable functional groups.The approach can be directly used to install benzyl and azole motifs on highly functionalized drug molecules.