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Stress corrosion is one of the main threats to titanium alloys used in marine equipment.In order to provide technical support for the safe service of marine equipment，the TC4ELI titanium alloy used in marine environment was selected as the research object，and its corrosion behavior in 3.5%NaCl solution under different microstructure states was systematically studied by using WOL (wedge-open loading) specimen and static displacement method to measure KISCC.The fracture morphology and crack propagation path of the stress corrosion specimens were observed by optical microscope (OM) and scanning electron microscope (SEM).The element distribution of the crack site was analyzed by secondary ion mass spectrometry (SIMS).Results indicated that the stress corrosion threshold (KISCC) of duplex microstructure (α＋β) sheet was 56.01 MPa·m1/2，and the stress corrosion threshold (KISCC) of Widmannstetter structure sheet was greater than 67.48 MPa·m1/2.The fracture surface of stress corrosion specimen was mainly composed of matrix，fatigue preformed zone and tearing zone.There was a stress corrosion zone at the interface between fatigue preformed zone and tearing zone of duplex microstructure specimen.In addition to the main crack，there were some secondary cracks at the crack tip for duplex microstructure specimen.There was no obvious stress corrosion cracking (SCC) feature in Widmannstetter structure specimen.The stress corrosion resistance of the Widmannstetter microstructure was better than that of duplex microstructure.The stress corrosion cracking of TC4ELI alloy duplex microstructure specimen was mainly transgranular fracture，and the hydrogen was easy to accumulate at the crack tip.

Phycobilisomes, the light‐harvesting complexes of cyanobacteria and red algae, are a resource for photosynthetic, photonic and fluorescence labeling elements. They cover an exceptionally broad spectral range, but the complex superstructure and assembly have been an obstacle. By replacing in Synechocystis sp. PCC 6803 the biliverdin reductases, we studied the role of chromophores in the assembly of the phycobilisome core. Introduction of the green‐absorbing phycoerythrobilin instead of the red‐absorbing phycocyanobilin inhibited aggregation. A novel, trimeric allophycocyanin (Dic‐APC) was obtained. In the small (110 kDa) unit, the two chromophores, phycoerythrobilin and phytochromobilin, cover a wide spectral range (550 to 660 nm). Due to efficient energy transfer, it provides an efficient artificial light‐harvesting element. Dic‐APC was generated in vitro by using the contained core‐linker, LC, for template‐assisted purification and assembly. Labeling the linker provides a method for targeting Dic‐APC. [ABSTRACT FROM AUTHOR]

Summary: Phycobilisomes are large light‐harvesting complexes attached to the stromal side of thylakoids in cyanobacteria and red algae. They can be remodeled or degraded in response to changing light and nutritional status. Both the core and the peripheral rods of phycobilisomes contain biliproteins. During biliprotein biosynthesis, open‐chain tetrapyrrole chromophores are attached covalently to the apoproteins by dedicated lyases. Another set of non‐bleaching (Nb) proteins has been implicated in phycobilisome degradation, among them NblA and NblB. We report in vitro experiments with lyases, biliproteins and NblA/B which imply that the situation is more complex than currently discussed: lyases can also detach the chromophores and NblA and NblB can modulate lyase‐catalyzed binding and detachment of chromophores in a complex fashion. We show: (i) NblA and NblB can interfere with chromophorylation as well as chromophore detachment of phycobiliprotein, they are generally inhibitors but in some cases enhance the reaction; (ii) NblA and NblB promote dissociation of whole phycobilisomes, cores and, in particular, allophycocyanin trimers; (iii) while NblA and NblB do not interact with each other, both interact with lyases, apo‐ and holo‐biliproteins; (iv) they promote synergistically the lyase‐catalyzed chromophorylation of the β‐subunit of the major rod component, CPC; and (v) they modulate lyase‐catalyzed and lyase‐independent chromophore transfers among biliproteins, with the core protein, ApcF, the rod protein, CpcA, and sensory biliproteins (phytochromes, cyanobacteriochromes) acting as potential traps. The results indicate that NblA/B can cooperate with lyases in remodeling the phycobilisomes to balance the metabolic requirements of acclimating their light‐harvesting capacity without straining the overall metabolic economy of the cell. Significance Statement: Cyanobacteria and red algae make a substantial contribution to global photosynthesis. Their success is, in part, due to large light‐harvesting complexes, phycobilisomes, with bilin chromophores. Phycobilisomes are subject to remodeling in response to changing light and nutritional status. We provide a scenario by which biosynthetic and degrading factors of phycobilisomes communicate by direct interaction, thereby adjusting aggregation and chromophore transfers relevant for the degradation and restructuring of phycobilisomes. [ABSTRACT FROM AUTHOR]