Driving factors of soil organic carbon sequestration under straw returning across China's uplands.

Straw returning is suggested as a sustainable agricultural practice to promote soil organic carbon (SOC) sequestration, whose magnitude can be influenced by climatic, edaphic and agronomic factors simultaneously. However, the driving factors regulating straw returning-induced SOC increase in China's uplands remain uncertain. This study conducted a meta-analysis by collecting data from 238 trials at 85 field sites. The results showed that straw returning significantly increased SOC content by an average of 16.1% ± 1.5% with an average sequestration rate of 0.26 ± 0.02 g kg-1 yr-1. The improvement effects were significantly better in the northern China (NE-NW-N) than in the eastern and central (E-C). SOC increases were more pronounced in C-rich and alkaline soils, in cold and dry climates, and under larger amounts of straw-C and moderate nitrogen fertilizer inputs. Longer experimental period resulted in higher SOC increase rates but lower SOC sequestration rates. Furthermore, partial correlation analysis and structural equation modelling revealed that total straw-C input was the key driving factor of SOC increase rate whereas straw returning duration was the dominant limiting factor of SOC sequestration rate across China. Climate conditions were potential limiting factors of SOC increase rate in NE-NW-N and SOC sequestration rate in E-C. It was suggested that straw returning with large application amounts should be more strongly recommended in uplands in NE-NW-N especially in the straw applications at the beginning, from the perspective of SOC sequestration.

[A new phloroglucinol compound from Dryopteris fragrans].

Two phloroglucinol compounds(1-2) were isolated and purified from 95% ethanol extract of Dryopteris fragrans through various column chromatographies on silica gel, Sephadex LH-20, medium pressure column chromatography, and preparative HPLC. Their structures were elucidated as 2',4',6'-trihydroxy-5'-methyl acetate-3'-methyl-1'-butyrophenone(1) and aspidinol B(2) based on their chemical and physicochemical methods and spectroscopic data. Compound 1 is a new phloroglucinol compound named "dryofraginol".

Two new glycosides from Dryopteris fragrans with anti-inflammatory activities.

Phytochemical investigation on the aqueous extract from Dryopteris fragrans led to the isolation of one new chromone glycoside, frachromone C (1), and one new coumarin glycoside, dryofracoulin A (2), together with one known undulatoside A (3). Their structures were elucidated by a combination of 1D and 2D NMR, HRMS, and chemical analysis. Compounds 1-3 exhibited inhibition on nitric oxide production in lipopolysaccharide induced RAW 264.7 macrophages with their IC50 values of 45.8, 65.8, and 49.8 µM, respectively.

Superhydrophobic Surface Preparation and Wettability Transition of Titanium Alloy with Micro/Nano Hierarchical Texture.

Microstructures are applied to various hydrophobic/hydrophilic surfaces due to the role of adjusting the surface wettability. In this paper, a 1064 nm pulsed picosecond laser was applied to prepare a micro/nano hierarchical structure on the surface of the titanium alloy (Ti-6Al-4V). The microstructures consist of dimple arrays with various diameters, depths, and areal densities. They are obtained by controlling the pulse energy and the number of pulses. The nanostructures are periodic ripples, which are defined as laser-induced periodic surface structure (LIPSS), and the dimensional parameter of LIPSS can be adjusted by changing the laser energy density and scanning speed. The contact angles of various laser textured surfaces were measured. It is found that the contact angle increases with the density of micro-textured surface increases, and the wetting state of textured surfaces conforms to the Cassie model. Some laser processed samples were subjected to low-temperature annealing treatment. It is observed that the low-temperature annealing process can accelerate the surface wettability transition significantly, which is attributed to the change of the hydroxyl groups on the surface. Finally, a superhydrophobic surface with the maximum contact angle of 144.58° is obtained.