Search

Over the past few decades, fiber-optic time synchronization (FOTS) has provided fundamental support for the efficient operation of modern society. Looking toward the future beyond fifth-generation/sixth-generation (B5G/6G) scenarios and very large radio telescope arrays, developing high-precision, low-complexity and scalable FOTS technology is crucial for building a large-scale time synchronization network. However, the traditional two-way FOTS method needs a data layer to exchange time delay information. This increases the complexity of system and makes it impossible to realize multiple-access time synchronization. In this paper, a time reversal enabled FOTS method is proposed. It measures the clock difference between two locations without involving a data layer, which can reduce the complexity of the system. Moreover, it can also achieve multiple-access time synchronization along the fiber link. Tests over a 230 km fiber link have been carried out to demonstrate the high performance of the proposed method.

Supplemental material

The aim of this study was to investigate the role of ethylene to control sprouting of potatoes by observing the effect of exogenous ethylene on carbohydrate metabolism and key enzymes. The initial time of potato tuber sprouting and sprouting index were recorded, and rate of respiration, total sugar, total reducing sugar, starch, fructose, glucose, sucrose and the activities of acid invertase (AI), neutral invertase (NI), sucrose synthase (SS), sucrose phosphate synthase (SPS), starch phosphorylase and amylase during sprouting were measured. Exogenous ethylene inhibited sprouting of potato tubers. Moreover, exogenous ethylene increased respiration total sugar, AI activity, SPS activity, SS activity, and reduced sugar and assay activity. Nevertheless, starch, glucose, fructose, NI activity and starch phosphorylase activity showed lower variation. Lower sprouting resulted into potatoes with higher levels of total sugar, total reducing sugar and glucose, and lower level of fructose and sucrose. And sprouting could be inhibited by increasing the activities of SS, SPS and AI by treatment with 199.3 μl L−1 exogenous ethylene. Overall, exogenous ethylene inhibited sprouting of potato tubers by influencing its carbohydrate metabolism.

Antioxidant properties of methanol extracts from Flos Lonicerae Japonicae (FLJ) flowers during maturation were determined with different antioxidant assays, including antioxidant activity in emulsion system, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, superoxide anion radical scavenging and reducing power. Antioxidant metabolites, such as chlorogenic acid, caffeic acid, rutin, 3,5-O-dicaffeoylquinic acid (3,5-O-diCQA) and 3,4-O-diCQA, were also identified and analyzed by DPPH–HPLC–DAD–TOF/MS method. Significant variation in antioxidant properties and related compounds was observed between different maturity stages, and the strongest antioxidant activity was observed at stage I accompanying the highest content of antioxidant compounds. Chlorogenic acid and its derivatives were the main antioxidant compounds in FLJ flowers, accounting for more than 90 % of total bioactive molecules. In summary, bud-developing-stage (stage I and stage II) FLJ flowers possess the highest functional benefit.