The complete chloroplast genome sequence of Gentiana triflora and comparative analysis with its congeneric species

Gentiana triflora is an important medicinal plant in China with economic and medicinal value. Here, we report the complete chloroplastsequences of G. trifloral. The cp genome of G. triflora of 149, 125 bp contains 130 unique genes, including 85 protein-coding genes,8 rRNA genes, and 37 tRNA genes. The analysis of repeat showed that palindromic had the highest frequency. Besides, a total numberof 45 SSR were identified, most of which were mononucleotide adenine-thymine. Comparative genome analysis of Gentiana speciesrevealed that the pair of the inverted repeat was more conserved than the single-copy region. This analysis resulted in identification of 8 hypervariable regions (trnH-GUG, trnG-UCC-intron, atpI, trnD-GUC, trnL-UAA, rpl32-trnL-UAG, petA and ycf1). Phylogenetic analysis revealed that G. triflora was most closely related to Gentiana manshurica. In conclusion, this study enriched the genomic resources of the Gentiana genus and provided a basis for evolution and phylogeny analyses

Revealing ecotype influences on Cistanche sinensis: from the perspective of endophytes to metabolites characteristics

IntroductionPlant microorganism is critical to plant health, adaptability, and productive forces. Intriguingly, the metabolites and microorganisms can act upon each other in a plant. The union of metabolomics and microbiome may uncover the crucial connections of the plant to its microbiome. It has important benefits for the agricultural industry and human being health, particularly for Chinese medical science investigation.MethodsIn this last 2 years study, on the strength of the UPLC–MS/MS detection platform, we accurately qualitatively, and quantitatively measured the Cistanche sinensis fleshy stems of two ecotypes. Thereafter, through high-throughput amplicon sequencing 16S/ITS sequences were procured.ResultsPhGs metabolites including echinacoside, isoacteoside, and cistanoside A were significantly downregulated at two ecotypes of C. sinensis. Add up to 876 metabolites were monitored and 231 differential metabolites were analyzed. Further analysis of 34 core differential metabolites showed that 15 compounds with up-regulated belonged to phenolic acids, flavonoids, and organic acids, while 19 compounds with down-regulated belonged to phenolic acids, flavonoids, alkaloids, amino acids, lipids, and nucleotides. There was no noteworthy discrepancy in the endophytic bacteria’s α and β diversity between sandy and loam ecotypes. By comparison, the α and β diversity of endophytic fungi was notably distinct. The fungal community of the loam ecotype is more abundant than the sandy ecotype. However, there were few such differences in bacteria. Most abundant genera included typical endophytes such as Phyllobacterium, Mycobacterium, Cistanche, Geosmithia, and Fusarium. LEfSe results revealed there were 11 and 20 biomarkers of endophytic bacteria and fungi in C. sinensis at two ecotypes, respectively. The combination parsing of microflora and metabolites indicated noteworthy relativity between the endophytic fungal communities and metabolite output. Key correlation results that Anseongella was positive relation with Syringin, Arsenicitalea is negative relation with 7-methylxanthine and Pseudogymnoascus is completely positively correlated with nepetin-7-O-alloside.DiscussionThe aim of this research is: (1) to explore firstly the influence of ecotype on C. sinensis from the perspective of endophytes and metabolites; (2) to investigate the relationship between endophytes and metabolites. This discovery advances our understanding of the interaction between endophytes and plants and provides a theoretical basis for cultivation of C. sinensis in future

Atmospheric new particle formation from sulfuric acid and amines in a Chinese megacity

Atmospheric new particle formation (NPF) is an important global phenomenon that is nevertheless sensitive to ambient conditions. According to both observation and theoretical arguments, NPF usually requires a relatively high sulfuric acid (H2SO4) concentration to promote the formation of new particles and a low preexisting aerosol loading to minimize the sink of new particles. We investigated NPF in Shanghai and were able to observe both precursor vapors (H2SO4) and initial clusters at a molecular level in a megacity. High NPF rates were observed to coincide with several familiar markers suggestive of H2SO4-dimethylamine (DMA)water (H2O) nucleation, including sulfuric acid dimers and H2SO4-DMA clusters. In a cluster kinetics simulation, the observed concentration of sulfuric acid was high enough to explain the particle growth to similar to 3 nanometers under the very high condensation sink, whereas the subsequent higher growth rate beyond this size is believed to result fromthe added contribution of condensing organic species. These findings will help in understanding urban NPF and its air quality and climate effects, as well as in formulating policies to mitigate secondary particle formation in China.Peer reviewe

Simple shear behavior of 2024-T351 aluminum alloy over a wide range of strain rates and temperatures: Experiments and constitutive modeling

A recently developed single shear specimen (SSS) was used to investigate the thermo-viscoplastic behavior of 2024-T351 aluminum alloy (AA2024-T351) under simple shear stress state. Shear stress-shear strain relations over a wide range of strain rates, covering low (0.001 and 0.1 s−1), medium (10 s−1), high (3000 and 6000 s−1) and very high (14000-49000 s−1) regimes and at initial temperatures from 293 to 573 K were obtained experimentally. The results show that: (1) at 293 K, AA2024-T351 exhibited negligible strain rate sensitivity at strain rates below 6000 s−1, and the effect of strain rate became obvious at strain rates above 14000 s−1; (2) dynamic strain aging (DSA) occurred at temperatures between 373 and 573 K and strain rates below 6000 s−1; (3) strain rate sensitivity of the material was strongly affected by DSA, and bell-shaped strain rate sensitivity curves were observed; (4) with an increase in temperature, peak values of the bell-shaped strain rate sensitivity curves shifted to higher strain rates. A constitutive model taking the advantages of Johnson-Cook model, Khan-Huang-Liang model, Nemat-Nasser-Li model and Wang-Guo-Gao model was developed for deformation behavior description, with the effects of viscous drag on dislocation motion and DSA considered. The experimental flow stress curves were compared to the model predictions, and a good agreement was observed. To validate the constitutive model independently of the experiments used for the identification of the model parameters, numerical simulations of Taylor impact tests were performed. A good agreement between experimental and numerical post-test specimens, in terms of mushroom shaped specimen head and reduced specimen length, was observed. According to the numerical results, strain rates varied largely between 103 and 106 s−1 during Taylor impact tests. Besides, numerical simulations of Taylor impact tests were performed again using the constitutive model excluding the viscous drag component, and less accurate numerical results were obtained. It implies that for precise computations of engineering applications, the actual strain rate should be considered in the establishment of constitutive models

Effect Of The Lode Parameter In Predicting Shear Cracking Of 2024-T351 Aluminum Alloy Taylor Rods

Recent investigations have shown that the ductility of a metal may depend on not only the stress triaxiality but also the Lode parameter, especially in the relatively low stress triaxiality range. However, applications using the Lode dependent fracture criterion are few and the value of incorporating the Lode parameter into a fracture criterion to predict impact related fracture is poorly understood. In the present paper, Taylor impact test by using 2024-T351 aluminum alloy rods of 5.95 mm diameter and 29.75 mm length was firstly conducted in a one-stage gas gun in the impact velocity range of 110.8–312.7 m/s. Mushrooming and shear cracking were observed in the test with increasing impact velocity. Subsequently, mechanical tests were conducted in a universal testing machine and a SHPB test facility. By using a hybrid experiment–numerical method, a modified version of Johnson–Cook strength model, a Lode-dependent fracture criterion as well as the Johnson–Cook (JC) fracture criterion were calibrated. Finally, 3D FE model corresponding to the test was built in ABAQUS and then was adopted to predict the shear cracking of the Taylor rods. It was found that FE simulations by using the Lode dependent fracture criterion give reasonable fracture pattern predictions while that using the Johnson–Cook fracture model obviously underestimates the fracture behavior. Detailed analysis shows that the dominant stress state of the material in the projectile\u27s fracture region in the impact event is in the range where the Lode parameter has an obvious influence on the metal\u27s ductility. FE simulations by using virtual metals also show that the Taylor impact fracture behavior prediction is much dependent on the effect of the Lode parameter on a material\u27s ductility

A Study of the Dynamic Mechanical Properties of Q460D Steel

The dynamic mechanical properties of Q460D steel were studied to facilitate an assessment of the impact resistance of building structures. In the present work, material performance tests of Q460D steel at different temperatures, strain rates, and stress states were conducted. Using a hybrid experimental–numerical approach, a modified Johnson–Cook (JC) constitutive relation, a modified Johnson–Cook (JC) fracture criterion, and a lode-dependent fracture criterion were calibrated. To validate the calibration, Taylor impact tests of Q460D steel rods onto rigid target plates were carried out in a one-stage light-gas gun system. Mushrooming, tensile splitting, and petalling failure modes were obtained as the impact velocity was increased from 191.6 to 422.1 m/s. A three-dimensional finite element model was built for the Taylor impact tests, and FE simulations were run using the material models calibrated. It was found that the FE simulations using the lode-dependent fracture criterion were reasonable in terms of the failure modes of the Taylor rods. In contrast, the fracture behavior of the Taylor rods was significantly underestimated using the lode-independent JC fracture criterion. Finally, the effect of anisotropy, strain rate sensitivity and yield plateau on the Taylor impact FE predictions were explored and discussed

Experimental and Numerical Study on the Protective Behavior of Weldox 900 E Steel Plates Impacted by Blunt-Nosed Projectiles

To demonstrate the importance of incorporating Lode angle into fracture criterion in predicting the penetration resistance of high-strength steel plates, ballistic tests of blunt-nosed projectiles with a diameter of 5.95 mm impacted 4 mm thick Weldox 900 E steel plates were conducted. Impacting velocity range was 136.63~381.42 m/s. The fracture behavior and the ballistic limit velocities (BLVs) were obtained by fitting the initial-residual velocities of the projectiles. Subsequently, axisymmetric finite element (FE) models parallel to the tests were built by using Abaqus/Explicit software, and the Lode-independent Johnson–Cook (JC) and the Lode-dependent ASCE fracture criterion were incorporated into the finite element model for numerical simulation. Meanwhile, to verify the sensitivity of the mesh size in the numerical simulation, different mesh sizes were used in the shear plug area of the target. It can be found that Weldox 900 E steel has obvious mesh size sensitivity by comparing the experimental results and numerical simulation, and the JC fracture criterion and the ASCE fracture criterion predicted similar BLV for the same mesh size

Experimental and Numerical Study on the Protective Behavior of Weldox 900 E Steel Plates Impacted by Blunt-Nosed Projectiles

To demonstrate the importance of incorporating Lode angle into fracture criterion in predicting the penetration resistance of high-strength steel plates, ballistic tests of blunt-nosed projectiles with a diameter of 5.95 mm impacted 4 mm thick Weldox 900 E steel plates were conducted. Impacting velocity range was 136.63~381.42 m/s. The fracture behavior and the ballistic limit velocities (BLVs) were obtained by fitting the initial-residual velocities of the projectiles. Subsequently, axisymmetric finite element (FE) models parallel to the tests were built by using Abaqus/Explicit software, and the Lode-independent Johnson–Cook (JC) and the Lode-dependent ASCE fracture criterion were incorporated into the finite element model for numerical simulation. Meanwhile, to verify the sensitivity of the mesh size in the numerical simulation, different mesh sizes were used in the shear plug area of the target. It can be found that Weldox 900 E steel has obvious mesh size sensitivity by comparing the experimental results and numerical simulation, and the JC fracture criterion and the ASCE fracture criterion predicted similar BLV for the same mesh size