Search

Surface modification of laser cladding coating NiCoCrAlY was carried out by high-current pulsed electron beam irradiation. The microstructure of the NiCoCrAlY coating after irradiation was studied by XRD and SEM. The results showed that the NiCoCrAlY cladding layer displays slip and a nanocrystalline structure following high-current pulsed electron beam irradiation. The high-density slip structure affects the residual stress on the surface of the melted coating, resulting in a change of the phase structure. The mechanical properties of the NiCoCrAlY coating were studied using a Vickers micro-hardness tester and a straight-line-reciprocating dry sliding wear tester. The results showed the average microhardness of the melted coating increased by 9%, and the average wear coefficient decreased by 33.7% after five electron beam irradiations. [ABSTRACT FROM AUTHOR]

Siderophore‐interacting proteins (SIPs) play an important role in iron acquisition in many bacteria. SIPs release iron from the internalized ferric siderophore complex by reducing ferric iron to ferrous iron, but how the iron is reduced is not well understood. Here, a sip gene was identified in the genome of Vibrio anguillarum 775. To further understand the catalytic mechanism of the protein, the SIP was overexpressed in Escherichia coli Rosetta (DE3) cells, purified and crystallized for X‐ray diffraction analysis. The crystal diffracted to 1.113 Å resolution and belonged to space group P21, with unit‐cell parameters a = 64.63, b = 58.47, c = 70.65 Å, β = 114.19°. [ABSTRACT FROM AUTHOR]

The imaging spectrometer's high performance in practical applications may be compromised by environmental factors, particularly temperature variations, posing a challenge to its stability. Temperature fluctuations can induce spectral shift, directly impacting the accuracy of spectral measurements, subsequently influencing the precision of radiometric measurements. To address this issue, this study investigates a dual-channel UV imaging spectrometer. This instrument boasts a wavelength calibration accuracy of 0.01 nm. This paper conducts an in-depth analysis of the various mechanisms through which temperature changes influence the spectral line offset in the imaging spectrometer, integrating actual orbital temperature data to discuss the instrument's temperature load settings. The impact of temperature on spectral shift is examined using finite element analysis and optical design software. Estimations of spectral shift were made based on temperature variations. Simulation results indicated that the maximum deviation of spectral shift is estimated at 0.018 nm under a temperature condition of 16 ± 1°C. Under a more controlled orbital temperature condition (16 ± 0.3°C), the maximum deviation of spectral shift decreased to 0.01 nm. Experimental data revealed that at 16 ± 1°C, the maximum deviation of spectral shift did not exceed 0.01 nm. This effectively corroborates our theoretical analysis. The relationship between temperature and spectral shift offers a crucial theoretical foundation for calibrating spectral measurements and managing the thermal conditions of the instrument.

Siderophore-interacting proteins (SIPs) play an important role in iron acquisition in many bacteria. SIPs release iron from the internalized ferric siderophore complex by reducing ferric iron to ferrous iron, but how the iron is reduced is not well understood. Here, a sip gene was identified in the genome of Vibrio anguillarum 775. To further understand the catalytic mechanism of the protein, the SIP was overexpressed in Escherichia coli Rosetta (DE3) cells, purified and crystallized for X-ray diffraction analysis. The crystal diffracted to 1.113 Å resolution and belonged to space group P2 1 , with unit-cell parameters a = 64.63, b = 58.47, c = 70.65 Å, β = 114.19°.

Rapid accumulations of unattached green macroalgae, referred to as blooms, constitute ecological disasters and occur in many coastal regions. Ulva are a major cause of blooms, owing to their high nitrogen utilization capacity, which requires nitrate reductase (NR) activity; however, molecular characterization of Ulva NR remains lacking. Herein we determined the crystal structure and performed an enzymatic analysis of the cytochrome b 5 reductase domain of Ulva prolifera NR (UpCbRNR). The structural analysis revealed an N-terminal FAD-binding domain primarily consisting of six antiparallel β strands, a C-terminal NADH-binding domain forming a Rossmann fold, and a three β-stranded linker region connecting these two domains. The FAD cofactor was located in the cleft between the two domains and interacted primarily with the FAD-binding domain. UpCbRNR shares similarities in overall structure and cofactor interactions with homologs, and its catalytic ability is comparable to that of higher plant CbRNRs. Structure and sequence comparisons of homologs revealed two regions of sequence length variation potentially useful for phylogenetic analysis: one in the FAD-binding domain, specific to U. prolifera, and another in the linker region that may be used to differentiate between plant, fungi, and animal homologs. Our data will facilitate molecular-level understanding of nitrate assimilation in Ulva., (Copyright © 2018 Elsevier B.V. All rights reserved.)