Sea-level change in coastal areas of China:Status in 2021

The sea level in coastal areas of China reached the second highest in 2021,just after that recorded in 2022.External force and dynamic analyses based on tide gauges,satellite observations,reanalysis data and regional numerical outputs were conducted to understand these abnormally high sea levels and determine their possible causes.Results show that the coastal sea level of China had increased at an annual rate of 3.4±0.3 mm during 1980-2021,with an acceleration of 0.06±0.02 mm per year2.The superposition of significant oscillations of quasi-2,3-7,quasi-9,quasi-11,quasi-19 and 20-30 years contributed to the anomalously high sea levels.The negative-phased El Nino/Southern Oscillation was correlated with the anomalously high sea level and the north-south anti-phase pattern of the coastal sea level in 2021.Meanwhile,phase lags of 1-4 months occurred with the sea-level response.On a decadal timescale,the Pacific Decadal Oscillation(PDO)was negatively correlated with the anomalous mean sea level(MSL),and the negative-phased PDO contributed to the anomalous sea-level change in 2021.Particularly,the monthly MSL peaked in April and July,and the contribution of wind stress to the anomalously high sea level was 38.5%in the south of the Taiwan Strait in April and 30%along the coast of China in July.These results were consistent with the tide gauge and satellite data.Close agreement was also observed between the coastal sea-level fingerprint and the air and sea surface temperatures.

Enzymatic synthesis of indigo derivatives by tuning P450 BM3 peroxygenases

Indigoids,a class of bis-indoles,have long been applied in dyeing,food,and pharmaceutical industries.Recently,interest in these‘old’molecules has been renewed in the field of organic semiconductors as functional building blocks for organic electronics due to their excellent chemical and physical properties.However,these indigo derivatives are difficult to access through chemical synthesis.In this study,we engineer cytochrome P450 BM3 from an NADPH-dependent monooxygenase to peroxygenases through directed evolution.A select number of P450 BM3 variants are used for the selective oxidation of indole derivatives to form different indigoid pigments with a spectrum of colors.Among the prepared indigoid organic photocatalysts,a majority of indigoids demonstrate a reduced band gap than indigo due to the increased light capture and improved charge separation,making them promising candidates for the development of new organic electronic devices.Thus,we present a useful enzymatic approach with broad substrate scope and cost-effectiveness by using low-cost H2O2 as a cofactor for the preparation of diversified indigoids,offering versatility in designing and manufacturing new dyestuff and electronic/sensor components.

The effect of crack tip environment on crack growth behaviour of a low alloy steel at cathodic potentials in artificial seawater

The environment at crack tip and its effect on the crack growth behaviour of low alloy steel-E690 steel were studied at cathodic potentials in artificial seawater.The results showed that the micro environment at crack tip and crack growth behaviour were related to the electrochemical reactions at crack tip,which were affected by the stress state and applied potentials.The crack tip environment was acidified under cyclic loading,resulting from the crack tip anodic dissolution reaction and corresponding hydrolysis reaction.Because of the hydrogen evolution and the inhibited anodic dissolution inside the crack,the crack tip p H increases as the cathodic potential decreases.The effect of cathodic potentials on the electrochemical reactions caused the variation of the hydrogen content,which influenced the crack growth rate because the crack growth behaviour was controlled by hydrogen embrittlement mechanism.This resulted in a fact that with the negative decrease of potential,the crack growth rate first decreased and then increased,with the minimum rate at-0.75 V.And the crack growth path exhibited transgranular fracture.