Resequencing of sweetpotato germplasm resources reveals key loci associated with multiple agronomic traits

Sweetpotato is an important crop that exhibits hexaploidy and high heterozygosity,which limits gene mining for important agronomic traits.Here,314 sweetpotato germplasm resources were deeply resequenced,and 4599509 SNPs and 846654 InDels were generated,among which 196124 SNPs were nonsynonymous and 9690 InDels were frameshifted.Based on the Indels,genome-wide marker primers were designed,and 3219 of 40366 primer pairs were selected to construct the core InDel marker set.The molecular ID of 104 sweetpotato samples verified the availability of these primers.The sweetpotato population structures were then assessed through multiple approaches using SNPs,and diverse approaches demonstrated that population stratification was not obvious for most Chinese germplasm resources.As many as 20 important agronomic traits were evaluated,and a genome-wide association study was conducted on these traits.A total of 19 high-confidence loci were detected in both models.These loci included several candidate genes,such as IbMYB1,IbZEP1,and IbYABBY1,which might be involved in anthocyanin metabolism,carotenoid metabolism,and leaf morphogenesis,respectively.Among them,IbZEP1 and IbYABBY1 were first reported in sweetpotato.The variants in the promoter and the expression levels of IbZEP1 were significantly correlated with f lesh color(orange or not orange)in sweetpotato.The expression levels of IbYABBY1 were also correlated with leaf shape.These results will assist in genetic and breeding studies in sweetpotato.

Characteristics of penetration and distribution of a liquid jet in a divergent cavity-based combustor

The atomization process of a liquid jet in a divergent cavity-based combustor was investigated experimentally using high-speed photography and schlieren techniques under a Mach number 2.0 supersonic crossflow.Gas-liquid flow field was studied at different divergent angles and injection schemes.It is found that complex wave structures exist in the divergent cavity-based combustor.The spray field can be divided into three distinct zones:surface wave-dominated breakup zone,rapid atomization zone and cavity mixing zone.A dimensionless spray factor is defined to describe the concentration of spray inside the cavity qualitatively.As a result,it is revealed that for the large divergent angle cavity,the injection scheme near the upstream inlet has a higher penetration depth but a lower spray distribution,where the injection scheme near the cavity has a more spray distribution.For the small divergent angle cavity,the injection scheme near the upstream inlet also has a higher penetration depth and the injection scheme near the start point of the divergent section has a more sufficient spray distribution.The small divergent angle cavity-based combustor with the upstream wall transverse injection is an optimized injection scheme to improve both penetration and spray distribution inside the cavity.Finally,a penetration depth formula is proposed to explain the spray and distribution behaviors in the divergent cavity-based combustor.

Review of atomization mechanism and spray characteristics of a liquid jet in supersonic crossflow

The injection and atomization process of a liquid fuel jet is critical for an ignition start of a scramjet engine.Airwall-mounted crossflow injection strategy is widely used in scramjet combustors,avoiding high total pressure loss and allowing the liquid fuel to rapidly undergo atomization,mixing,and evaporation.In this review,research progress on a liquid jet in supersonic crossflow was evaluated from aspects of atomization mechanism and spray characteristics.When a liquid jet is injected into a supersonic crossflow,primary and secondary breakups occur successively.The surface instability of liquid can significantly affect the breakup process.This review discusses the current understanding of the breakup process and spray characteristics of a liquid jet in supersonic crossflow including the mechanism of atomization and the characteristics of distribution and atomization.The development of windward Rayleigh-Taylor(R-T)unstable waves is the main factor in column breakup.The development of Kelvin-Helmholtz(K-H)unstable waves along the circumferential direction of the jet or droplets is the main factor of surface and droplet breakups.The liquid-gas momentum ratio is the most important factor affecting the penetration depth.The span width of the liquid jet is affected by the windward area.Breakup and coalescence lead to a transformation of the size distribution of droplets from S-or C-shaped to I-shaped,and the velocity distribution of the droplets on the central symmetry plane has a mirrored S-shape.The droplet distribution on the spanwise cross-section retains a structure similar to an“Ω”shape.At last,some promising recommendations have been proposed,namely a theoretical predictive model which can describe the breakup mechanism of a liquid jet,the distribution characteristics and droplets size distribution of a liquid jet under a cavity combustion chamber,especially for enthalpy flows with complex wave structures.

Enzymatic Synthesis of a Diastereomer of Neoabyssomicin Derivative Using the Diels-Alderase AbyU

Main observation and conclusion The enzyme AbyU catalyses a Diels-Alder(DA)reaction during abyssomicin C biosynthesis.In this study,AbyU is shown to convert the native substrate of another Diels-Alderase(DAase),AbmU,to a new abyssomicin derivative,abyssomicin 7.

Gas film/regenerative composite cooling characteristics of the liquid oxygen/liquid methane (LOX/LCH4) rocket engine

The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling model.The accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust chamber.Additionally,key parameters related to heat transfer performance were calculated.The results demonstrate that the model is sufficiently accurate to be used as a preliminary design tool.The temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer analysis.In addition,the performance of composite cooling is observed to be superior to regenerative cooling.Increasing the gas film flow rate results in higher cooling efficiency and a lower gas-side wall temperature.Furthermore,the position at which the gas film is introduced greatly impacts the cooling performance.The optimal introduction position for the gas film is determined when the film is introduced from a single row of holes.This optimal introduction position results in a more uniform wall temperature distribution and reduces the peak temperature.Lastly,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall temperature.These results provide a basis for the design of gas film/regenerative composite cooling systems.