Thermal–hydraulic analysis of space nuclear reactor TOPAZ-II with modified RELAP5

Wang, Chenglong; Liu, Tiancai; Tang, Simiao; Tian, Wenxi; Qiu, Suizheng; Su, G.H.

doi:10.1007/s41365-018-0537-3

Cited by 11 publications

(2 citation statements)

References 13 publications

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“…TV24/VA34 P protein native and complex (TV24 with type A tetrasaccharide) crystals were mainly mounted and collected at the BL17U beamline of the Shanghai Synchrotron Radiation Facility (SSRF) [41] and the BL5A KEK (Tsukuba, Japan) respectively. All datasets were collected under 100 K conditions and processed by HKL2000 programme [42].…”

Section: Methodsmentioning

confidence: 99%

Structural basis of host ligand specificity change of GII porcine noroviruses from their closely related GII human noroviruses

Yang

Xia

Wang

et al. 2019

Emerging Microbes & Infections

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Diverse noroviruses infect humans and animals via the recognition of host-specific glycan ligands. Genogroup II (GII) noroviruses consist of human noroviruses (huNoVs) that generally bind histo-blood group antigens (HBGAs) as host factors and three porcine norovirus (porNoV) genotypes (GII.11/18/19) that form a genetic lineage lacking HBGA-binding ability. Thus, these GII porNoVs provide an excellent model to study norovirus evolution with host ligand specificity changes. Here we solved the crystal structures of a native GII.11 porNoV P protein and a closely-related GII.3 huNoV P protein complexed with an HBGA, focusing on the HBGA-binding sites (HBSs) compared with the previously known ones to understand the structural basis of the host ligand specificity change. We found that the GII.3 huNoV binds HBGAs via a conventional GII HBS that uses an arginine instead of the conserved aromatic residue for the required Van der Waals interaction, while the GII.11 porNoV HBS loses its HBGA-binding function because of two mutations (Q355/V451). A mutant that reversed the two mutated residues back to the conventional A355/Y451 restored the HBGA-binding function of the GII.11 porNoV P protein, which validated our observations. Similar mutations are also found in GII.19 porNoVs and a GII.19 P protein mutant with double reverse mutations restored the HBS function. This is the first reconstruction of a functional HBS based on one with new host specificity back to its parental one. These data shed light on the molecular basis of structural adaptation of the GII porNoVs to the pig hosts through mutations at their HBSs.

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Section: Methodsmentioning

confidence: 99%

Structural basis of host ligand specificity change of GII porcine noroviruses from their closely related GII human noroviruses

Yang

Xia

Wang

et al. 2019

Emerging Microbes & Infections

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“…The development of advanced and reliable space power will become hugely important in order to achieve these ambitious milestones. Compared to typical power sources used in space, such as chemical fuel cells or solar photovoltaic arrays, the space nuclear reactor power is characterized by wider power coverage and longer operating duration; as such, it is regarded as a promising technology for human space exploration [1][2][3]. Among existing technology roadmaps of space nuclear reactors, the gas-cooled nuclear reactor combined with a closed Brayton cycle is perceived as the most rational scheme for the system power exceeding 200 kW [4][5][6]; this is because it can achieve a higher energy conversion efficiency and a smaller specific mass.…”

mentioning

confidence: 99%

Nusselt number correlation for turbulent heat transfer of helium–xenon gas mixtures

Zhou

Sun

et al. 2021

NUCL SCI TECH

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A gas-cooled nuclear reactor combined with a Brayton cycle shows promise as a technology for high-power space nuclear power systems. Generally, a helium–xenon gas mixture with a molecular weight of 14.5–40.0 g/mol is adopted as the working fluid to reduce the mass and volume of the turbomachinery. The Prandtl number for helium–xenon mixtures with this recommended mixing ratio may be as low as 0.2. As the convective heat transfer is closely related to the Prandtl number, different heat transfer correlations are often needed for fluids with various Prandtl numbers. Previous studies have established heat transfer correlations for fluids with medium–high Prandtl numbers (such as air and water) and extremely low-Prandtl fluids (such as liquid metals); however, these correlations cannot be directly recommended for such helium–xenon mixtures without verification. This study initially assessed the applicability of existing Nusselt number correlations, finding that the selected correlations are unsuitable for helium–xenon mixtures. To establish a more general heat transfer correlation, a theoretical derivation was conducted using the turbulent boundary layer theory. Numerical simulations of turbulent heat transfer for helium–xenon mixtures were carried out using Ansys Fluent. Based on simulated results, the parameters in the derived heat transfer correlation are determined. It is found that calculations using the new correlation were in good agreement with the experimental data, verifying its applicability to the turbulent heat transfer for helium–xenon mixtures. The effect of variable gas properties on turbulent heat transfer was also analyzed, and a modified heat transfer correlation with the temperature ratio was established. Based on the working conditions adopted in this study, the numerical error of the property-variable heat transfer correlation was almost within 10%.

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Combinatorial evolution of phosphotriesterase toward a robust malathion degrader by hierarchical iteration mutagenesis

Luo

Zhao

et al. 2016

Biotech & Bioengineering

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Malathion is one of the most widely used organophosphorus pesticides in the United States and developing countries. Herein, we enhanced the degradation rate of malathion starting with a phosphotriesterase PoOPHM2 while also considering thermostability. In the first step, iterative saturation mutagenesis at residues lining the binding pocket (CASTing) was employed to optimize the enzyme active site for substrate binding and activity. Hot spots for enhancing activity were then discovered through epPCR-based random mutagenesis, and these beneficial mutations were then recombined by DNA shuffling. Finally, guided by in silico energy calculations (FoldX), thermostability of the variant was improved. The mutations extend from the core region to the enzyme surface during the evolutionary pathway. After screening <9,000 mutants, the best variant PoOPHM9 showed 25-fold higher activity than wild-type PoOPHM2 , with a thermostability (T50 (15) ) of 67.6°C. Thus, PoOPHM9 appears to be an efficient and robust candidate for malathion detoxification. Biotechnol. Bioeng. 2016;113: 2350-2357. © 2016 Wiley Periodicals, Inc.

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Thermal–hydraulic analysis of space nuclear reactor TOPAZ-II with modified RELAP5

Cited by 11 publications

References 13 publications

Structural basis of host ligand specificity change of GII porcine noroviruses from their closely related GII human noroviruses

Structural basis of host ligand specificity change of GII porcine noroviruses from their closely related GII human noroviruses

Nusselt number correlation for turbulent heat transfer of helium–xenon gas mixtures

Combinatorial evolution of phosphotriesterase toward a robust malathion degrader by hierarchical iteration mutagenesis

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