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Abstract The good combination of high strength and high toughness is a long‐standing challenge in the design of robust biomaterials. Meanwhile, robust biomaterials hardly perform fast and significant mechanical property changes under the trigger of light at room temperature. These limit the application of biomaterials in some specific areas. Here, photoresponsive alginate fibers are fabricated by using the designed azobenzene‐containing surfactant as flexible contact point for cross‐linking polysaccharide chains of alginate, which gain high mechanics through reinforced plastic strain and photo‐modulating mechanics through isomerization of azobenzene. By transferring molecular motion into macro‐scale mechanical property changes, such alginate fibers achieve reversible photo‐modulations on the mechanics. Their breaking strength and toughness can be photo‐modulated from 732 MPa and 112 MJ m−3 to 299 MPa and 27 MJ m−3, respectively, leading to record high mechanical changes among the developed smart biomaterials. With merits of good tolerance to pH and temperature, fast response to light, and good biocompatibility, the reported fibers will be suitable for working in various application scenarios as new smart biomaterials. This study provides a new design strategy for gaining highly‐strong and highly‐tough photoresponsive biomaterials.

As an indispensable part of cement slurry for high temperature and high pressure oil and gas wells, weighting materials have a significant impact on the carbon dioxide corrosion of oil well cement-based composites.This paper studied the carbonation process of cement with three weighting agents, and evaluated the compressive strength and carbonation depth of cement at 150 ℃. XRD, SEM and MIP were used to study the carbonation mechanism of cement. When 21 days of carbonation, the carbonation depth growth rate of hausmannite cement was 0.21 mm/d, hematite cement was 0.24 mm/d, and barite cement was 0.31 mm/d. The compressive strength of cement decreased after carbonation,and the carbonation had a minor influence on the compressive strength of hausmannite cement and the most significant impact on barite cement. The carbonation product of oil well cement was mainly calcite. Unstable vaterite mainly existed in the barite cement sample, indicating that the barite cement sample was the most serious corrosion. In the carbonation zone, the number of pores smaller than 10 nm increased the most in the hausmannite cement sample. Pores with a diameter greater than 100 nm accounted for 1.9 % in the hausmannite cement, 3.0 % in hematite cement, and 4.8 % in barite cement. The result shows that hausmannite is the most conducive to the corrosion resistance of oil well cement.

A novel synthesis of the aggregation pheromone of the Colorado potato beetle, Leptinotarsa decemlineata, has been developed based on a Sharpless asymmetric epoxidation in combination with a chemoselective alcohol oxidation using catalytic [(neocuproine)PdOAc]2OTf2. Employing this approach, the pheromone was synthesized in 3 steps, 80% yield and 86% ee from geraniol.

Mangiferin, isomangiferin and homomangiferin, the xanthone C-glycosides with a wide spectrum of pharmacological effects, are prepared, featuring a C-glycosylation of a xanthene derivative with perbenzylglucopyranosyl N-phenyltrifluoroacetimidate.

We prove a cabling formula for the concordance invariant ν+, defined by the author and Hom in a previous work. This gives rise to a simple and effective four-ball genus bound for many cable knots. [ABSTRACT FROM AUTHOR]

Two Dehn surgeries on a knot are called purely cosmetic, if they yield manifolds that are homeomorphic as oriented manifolds. Suppose there exist purely cosmetic surgeries on a knot in S³, we show that the two surgery slopes must be the opposite of each other. One ingredient of our proof is a Dehn surgery formula for correction terms in Heegaard Floer homology. [ABSTRACT FROM AUTHOR]