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Ammonia-oxidizing archaea (AOA) are among the most ubiquitous and abundant archaea on Earth, widely distributed in marine, terrestrial, and geothermal ecosystems. However, the genomic diversity, biogeography, and evolutionary process of AOA populations in subsurface environments are vastly understudied compared to those in marine and soil systems. Here, we report a novel AOA order Candidatus (Ca.) Nitrosomirales which forms a sister lineage to the thermophilic Ca. Nitrosocaldales. Metagenomic and 16S rRNA gene-read mapping demonstrates the abundant presence of Nitrosomirales AOA in various groundwater environments and their widespread distribution across a range of geothermal, terrestrial, and marine habitats. Terrestrial Nitrosomirales AOA show the genetic capacity of using formate as a source of reductant and using nitrate as an alternative electron acceptor. Nitrosomirales AOA appear to have acquired key metabolic genes and operons from other mesophilic populations via horizontal gene transfer, including genes encoding urease, nitrite reductase, and V-type ATPase. The additional metabolic versatility conferred by acquired functions may have facilitated their radiation into a variety of subsurface, marine, and soil environments. We also provide evidence that each of the four AOA orders spans both marine and terrestrial habitats, which suggests a more complex evolutionary history for major AOA lineages than previously proposed. Together, these findings establish a robust phylogenomic framework of AOA and provide new insights into the ecology and adaptation of this globally abundant functional guild.

The RBCC (rocket-based combined-cycle) engine integrates a rocket engine into the flow passage of the ramjet engine, thereby significantly broadening the operating range and becoming one of the potential solutions for the reusable space transportations. The embedded rocket, as one of the core components of an RBCC engine, is strongly coupled to other components, such as the inlet and combustor, and can induce significant impacts on the inlet start behaviors. For the stable operation of the RBCC inlet, the start/unstart hysteresis characteristics and the reliable start boundaries driven by embedded rocket are experimentally and numerically studied. The results show that due to the function of embedded rocket jet, the inlet start/unstart hysteresis range of Mach number rises from Mach 1.79–1.87 to 1.85–1.90, and the back pressure hysteresis range changes from Pc/P∞ of 3.9–5.8 to 4.7–5.8. Meanwhile, during the increasing and decreasing process of the embedded rocket pressure, the inlet undergoes a transition between start and unstart, accompanied by hysteresis phenomena as well. Furthermore, three different control strategies are proposed for the start of RBCC inlet. Similar to the traditional ramjet inlets, the RBCC inlet can self-/re-start by reducing the back pressure. Particularly, owing to the synergistic effect of embedded rocket jet and back pressure, the RBCC inlet can self-/re-start by reducing the embedded rocket pressure from Procket/P∞ = 58 to 39 in the "embedded rocket dominated" cases, while the inlet self-/re-start can be achieved by increasing the rocket pressure from Procket/P∞ = 20 to 39 in the "back pressure dominated" cases. [ABSTRACT FROM AUTHOR]

The dynamic flow behaviors, as well as the propagation and coupling of regulation information, in a rocket-based combined-cycle inlet isolator during the ejector-to-ramjet mode transitions driven by different embedded rocket control methods, are numerically investigated. The key parameters of compression power, Mach number, and pressure ratio are used to illustrate the operation performance of the inlet isolator. The rocket jet induces strong shocks while inhibiting the shock/boundary layer interaction in the jet-covered region. The coupling of the rocket jet shear and back pressure is linked to the formation of wall flow separation. The parameter distributions are greatly influenced by the destruction of shock structures, which is crucial for the stability of supersonic flowfields. The continuity of the jet boundary is disrupted by the regulation of the embedded rocket, and an increase in the throttle level will further intensify the breakup. Back pressure propagation is limited by the rocket jet and is constantly matched with the jet and mainstream until the rocket's influence domain reaches stable. The "high throttle-maintaining" and "direct-shutdown" mode transitions tend to induce oscillations in the isolator compression performance. In the "direct-shutdown" mode transition, the vorticity proportion in the combustor is unstable and the flowfield disorder is high. In the "high throttle-maintaining" mode transition, the vortex generation level is relatively stable and high, while the entropy proportion fluctuates strongly and at a high level. By adopting the "medium throttle-maintaining" mode transition, the entropy and vorticity proportion levels are relatively stable, which is conducive to the stability of mode transition. [ABSTRACT FROM AUTHOR]

This paper investigates conditional configurations for improving high‐tech enterprises' new product development (NPD) performance under complex environment of digital era in China. The results indicate that digital transformation is neither sufficient nor necessary for high NPD performance but a significant component of those configurations for high NPD performance. Through the fuzzy‐set qualitative comparative analysis (fsQCA) approach, four configurations for high NPD performance and four configurations for non‐high NPD performance are generated from complex nonlinear interactions among five antecedent conditions of NPD performance. Our findings enrich the literature on NPD performance and provide references on enterprises' decision making on digital transformation. [ABSTRACT FROM AUTHOR]