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This work revisits a publication by Beanet al.(2018) that reports seven amino acid substitutions are essential for the evolution ofl‐DOPA 4,5‐dioxygenase (DODA) activity in Caryophyllales. In this study, we explore several concerns which led us to replicate the analyses of Beanet al.(2018).

Our comparative analyses, with structural modelling, implicate numerous residues additional to those identified by Beanet al.(2018), with many of these additional residues occurring around the active site of BvDODAα1. We therefore replicated the analyses of Beanet al.(2018) to re‐observe the effect of their original seven residue substitutions in a BvDODAα2 background, that is the BvDODAα2‐mut3 variant.

Multiplein vivoassays, in bothSaccharomyces cerevisiaeandNicotiana benthamiana, did not result in visible DODA activity in BvDODAα2‐mut3, with betalain production always 10‐fold below BvDODAα1.In vitroassays also revealed substantial differences in both catalytic activity and pH optima between BvDODAα1, BvDODAα2 and BvDODAα2‐mut3 proteins, explaining their differing performancein vivo.

In summary, we were unable to replicate thein vivoanalyses of Beanet al.(2018), and our quantitativein vivoandin vitroanalyses suggest a minimal effect of these seven residues in altering catalytic activity of BvDODAα2. We conclude that the evolutionary pathway to high DODA activity is substantially more complex than implied by Beanet al.(2018).

 

Catalytic asymmetric α-alkylation of carbonyl compounds represents a long-standing challenge in synthetic organic chemistry. Herein, we advance a dual biocatalytic platform for the efficient asymmetric alkylation of α-keto acids. First, guided by our recently obtained crystal structures, we develop SgvM^VAVas a general biocatalyst for the enantioselective methylation, ethylation, allylation and propargylation of a range of α-keto acids with total turnover numbers (TTNs) up to 4,600. Second, we mine a family of bacterial HMTs fromPseudomonasspecies sharing less than 50% sequence identities with known HMTs and evaluated their activities in SAM regeneration. Our best performing HMT fromP. aeruginosa,PaHMT, displays the highest SAM regeneration efficiencies (TTN up to 7,700) among HMTs characterized to date. Together, the synergistic use of SgvM^VAVandPaHMT affords a fully biocatalytic protocol for asymmetric methylation featuring a record turnover efficiency, providing a solution to the notorious problem of asymmetric alkylation.

 

It has been widely suggested in literature that a lithium fluoride (LiF)-rich solid electrolyte interphase (SEI) affects Coulombic efficiency (CE) of the Li metal anode used with liquid electrolytes. Yet, the influence of LiF on Li metal deposition has been challenging to examine. Herein, we developed a method to synthesize LiF nanoscale particles with tunable sizes (30–300 nm) on Cu electrodes by electrochemical reduction of fluorinated gases under controlled discharge rates and capacities. The impact of LiF nanoparticles on overpotential and morphology of Li deposition was further studied in a conventional carbonate electrolyte. By cyclic voltammetry, Li plating overpotentials exhibit a clear correlation with the total surface area of LiF particles. Additionally, Li metal deposits (10μAh cm⁻²) nucleated under galvanostatic conditions (0.5 mA cm⁻²) on Cu/LiF showed increasing feature sizes with a lower average LiF particle size and higher coverage of LiF. However, no significant improvement in CE was observed for LiF-coated Cu. Our findings provide evidence that a particle-based mode of SEI fluorination can influence early-stage Li nucleation to a modest degree, and this effect is maximized when LiF is uniformly and densely distributed. However, sparser and larger LiF have vanishing or even detrimental effect on cycling performance.

 

Collaborative localization is an essential capability for a team of robots such as connected vehicles to collaboratively estimate object locations from multiple perspectives with reliant cooperation. To enable collaborative localization, four key challenges must be addressed, including modeling complex relationships between observed objects, fusing observations from an arbitrary number of collaborating robots, quantifying localization uncertainty, and addressing latency of robot communications. In this paper, we introduce a novel approach that integrates uncertainty-aware spatiotemporal graph learning and model-based state estimation for a team of robots to collaboratively localize objects. Specifically, we introduce a new uncertainty-aware graph learning model that learns spatiotemporal graphs to represent historical motions of the objects observed by each robot over time and provides uncertainties in object localization. Moreover, we propose a novel method for integrated learning and model-based state estimation, which fuses asynchronous observations obtained from an arbitrary number of robots for collaborative localization. We evaluate our approach in two collaborative object localization scenarios in simulations and on real robots. Experimental results show that our approach outperforms previous methods and achieves state-of-the-art performance on asynchronous collaborative localization. 

A sample of 279 massive red spirals was selected optically by Guo et al., among which 166 galaxies have been observed by the ALFALFA survey. In this work, we observe H i content of the rest 113 massive red spiral galaxies using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). 75 of the 113 galaxies have H i detection with a signal-to-noise ratio (S/N) greater than 4.7. Compared with the red spirals in the same sample that have been observed by the ALFALFA survey, galaxies observed by FAST have on average a higher S/N, and reach to a lower H i mass. To investigate why many red spirals contain a significant amount of H i mass, we check colour profiles of the massive red spirals using images observed by the DESI Legacy Imaging Surveys. We find that galaxies with H i detection have bluer outer discs than the galaxies without H i detection, for both ALFALFA and FAST samples. For galaxies with H i detection, there exists a clear correlation between galaxy H i mass and g-r colour at outer radius: galaxies with higher H i masses have bluer outer discs. The results indicate that optically selected massive red spirals are not fully quenched, and the H i gas observed in many of the galaxies may exist in their outer blue discs.

 

In this paper, we showcase a framework for cooperative mixed traffic platooning that allows the platooning vehicles to realize multiple benefits from using vehicle-to- everything (V2X) communications and advanced controls on urban arterial roads. A mixed traffic platoon, in general, can be formulated by a lead and ego connected automated vehicles (CAVs) with one or more unconnected human-driven vehicles (UHVs) in between. As this platoon approaches an intersection, the lead vehicle uses signal phase and timing (SPaT) messages from the connected intersection to optimize its trajectory for travel time and energy efficiency as it passes through the intersection. These benefits carry over to the UHVs and the ego vehicle as they follow the lead vehicle. The ego vehicle then uses information from the lead vehicle received through basic safety messages (BSMs) to further optimize its safety, driving comfort, and energy consumption. This is accomplished by the recently designed cooperative adaptive cruise control with unconnected vehicles (CACCu). The performance benefits of our framework are proven and demonstrated by simulations using real-world platooning data from the CACC Field Operation Test (FOT) Dataset from the Netherlands.