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Main protease (M pro) serves as an indispensable factor in the life cycle of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as well as its constantly emerging variants and is therefore considered an attractive target for antiviral drug development. Benzothiazole-based inhibitors targeting M pro have recently been investigated by several groups and proven to be promising leads for coronaviral drug development. In the present study, we determine the crystal structures of a benzothiazole-based inhibitor, YH-53, bound to M pro mutants from SARS-CoV-2 variants of concern (VOCs) or variants of interest (VOIs), including K90R (Beta, B.1.351), G15S (Lambda, C.37), Y54C (Delta, AY.4), M49I (Omicron, BA.5) and P132H (Omicron, B.1.1.529). The structures show that the benzothiazole group in YH-53 forms a C-S covalent bond with the sulfur atom of catalytic residue Cys145 in SARS-CoV-2 M pro mutants. Structural analysis reveals the key molecular determinants necessary for interaction and illustrates the binding mode of YH-53 to these mutant M pros. In conclusion, structural insights from this study offer more information to develop benzothiazole-based drugs that are broader spectrum, more effective and safer.

To improve the guidance for the wind tunnel test, this study initially conducted thorough research on the wind environment at a coastal bridge site to ascertain the characteristics of the wind parameters varying along the bridge span. Subsequently, the measured results were utilized to steer wind tunnel test research, focusing on analyzing the influence of the spoiler and maintenance track on the second-order heaving vortex-induced vibration of the flat steel box girder. This investigation uncovered two distinct distributions in the angle of attack along the span: bimodal distribution and asymmetric unimodal distribution. The angle of attack of the incoming flow was primarily concentrated within ±5°. Both the two-side and the windward spoiler were found to exert similar effects on the second-order heaving vortex-induced vibration, primarily impacting the second lock-in region. Furthermore, the outer maintenance track could effectively suppress the vortex-induced vibration, while the spacing of the inner maintenance track significantly affected the vortex-induced vibration at high wind speeds. [ABSTRACT FROM AUTHOR]

Camouflage spots are mostly color patches of different colors. Compared with the traditional empirical color matching method, computer color matching can quickly and effectively calculate the proportion of red, yellow, and blue primary colors. In general, camouflage computer color matching in the practical application of the initial formula is not accurate and multiple color modification still cannot match. First, we measured the chroma coordinates of 98 standard swatches made of red, green, and blue coatings in different proportions by the OHSP-660 spectral reflectance tester. Then, we adopted polynomial regression algorithm by Statistical Product and Service Solutions (SPSS) to obtain the regression equation between L * , a * , b * , and (x , y). Finally, the fitting equation is used to obtain the paint color scheme in the coordinates of L * , a * , and b * in arbitrary uniform color space, so as to realize the purpose of computer color matching. The experimental results show that the minimum color difference is 1.691 (L * a * b * unit) the maximum color difference is 2.497, which meets the design requirements of camouflage and target color difference being no more than 3. Our work provides a theoretical basis for the further development of computer color matching system in camouflage. [ABSTRACT FROM AUTHOR]