Numerical simulation and optimized design of cased telescoped ammunition interior ballistic

In order to achieve the optimized design of a cased telescoped ammunition(CTA) interior ballistic design,a genetic algorithm was introduced into the optimal design of CTA interior ballistics with coupling the CTA interior ballistic model. Aiming at the interior ballistic characteristics of a CTA gun, the goal of CTA interior ballistic design is to obtain a projectile velocity as large as possible. The optimal design of CTA interior ballistic is carried out using a genetic algorithm by setting peak pressure, changing the chamber volume and gun powder charge density. A numerical simulation of interior ballistics based on a 35 mm CTA firing experimental scheme was conducted and then the genetic algorithm was used for numerical optimization. The projectile muzzle velocity of the optimized scheme is increased from 1168 m/s for the initial experimental scheme to 1182 m/s. Then four optimization schemes were obtained with several independent optimization processes. The schemes were compared with each other and the difference between these schemes is small. The peak pressure and muzzle velocity of these schemes are almost the same. The result shows that the genetic algorithm is effective in the optimal design of the CTA interior ballistics. This work will be lay the foundation for further CTA interior ballistic design.

Gibberellin repression of axillary bud formation in Arabidopsis by modulation of DELLA-SPL9 complex activity

The formation of lateral branches has an important and fundamental contribution to the remarkable developmental plasticity of plants,which allows plants to alter their architecture to adapt to the challenging environment conditions.The Gibberellin(GA)phytohormones have been known to regulate the outgrowth of axillary meristems(AMs),but the specific molecular mechanisms remain unclear.Here we show that DELLA proteins regulate axillary bud formation by interacting and regulating the DNA-binding ability of SQUAMOSA-PROMOTER BINDING PROTEIN LIKE 9(SPL9),a micro RNA156-targeted squamosa promoter binding protein-like transcription factor.SPL9 participates in the initial regulation of axillary buds by repressing the expression of LATERAL SUPPRESSOR(LAS),a key regulator inthe initiation of AMs,and LAS contributes to the specific expression pattern of the GA deactivation enzyme GA2ox4,which is specifically expressed in the axils of leaves to form a low-GA cell niche in this anatomical region.Nevertheless,increasing GA levels in leaf axils by ectopically expressing the GA-biosynthesis enzyme GA20ox2 significantly impaired axillary meristem initiation.Our study demonstrates that DELLA-SPL9-LAS-GA2ox4 defines a core feedback regulatory module that spatially pattern GA content in the leaf axil and precisely control the axillary bud formation in different spatial and temporal.

Arabidopsis adaptor protein 1G is critical for pollen development

Pollen development is a,pre-requisite for sexual reproduction of angiosperms, during which various cellular activities are involved. Pollen development accompanies dynamic remodeling of vacuoles through fission and fusion, disruption of which often compromises pollen viability. We previously reported that the Y subunit of adaptor protein 1 （AP1G） mediates synergid degeneration during pollen tube reception. Here, we demonstrate that AP1G is essential for pollen development. AP1G loss-of-function resulted in male gametophytic lethality due to defective pollen development. By ultrastructural analysis and fluorescence labeling, we demonstrate that AP1G loss-of-function compromised dynamic vacuolar remodeling during pollen development and impaired vacuolar acidification of pollen. Results presented here support a key role of vacuoles in gametophytic pollen development.