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• The first complete chloroplast genome of phylica genus (Phylica pubescens) was sequenced. • Several unique chloroplast genome characters in phylica pubescens and its closely related rhamnaceae species were identified to explore evolutionary pattern. • 15 highly variable regions have been identified, which could be useful for phylogenetic analysis. • Based on complete chloroplast genomes, the phylogenetic tree of rhamnaceae was reconstructed. Phylica pubescens is closely related to spyridium species. • These findings provide insights into the evolutionary history of phylica pubescens and its relationship to other rhamnaceae species. Phylica (Rhamnaceae) plants are mainly distributed in southern Africa and nearby islands. They play a crucial role in studying diversification rates, climate change, and vegetation evolution in the Cape Flora. However, there have been no reports on the complete chloroplast genome of Phylica species, which is essential for investigating evolution and phylogenetic relationships. Herein, we sequenced the complete chloroplast genome of Phylica pubescens and conducted a comparative analysis with 12 Rhamnaceae species. The chloroplast genome size of Phylica pubescens was 161,187 bp, similar to that of other Rhamnaceae species. The absence of infA and psbL genes in certain Rhamnaceae species, compared to Phylica pubescens , has no apparent impact on these species. Positive selection has been observed in the rpl32, psbK , and psbH genes of Rhamnaceae species. Some highly variable regions (trnH -GUG– psbA, trnK -UUU– rps16, rps16 – trnQ -UUG, trnS -GCU– trnG -UCC, trnR -UCU– atpA, atpH – atpI, trnC -GCA– petN, trnT -GGU– psbD, psbZ – trnG -GCC, trnT -UGU– trnL -UAA, ndhC – trnV -UAC, accD – psaI, petA – psbJ, ndhF – rpl32 , and rpl32 – trnL -UAG) were identified, which might be useful for phylogenetic analysis. Based on complete chloroplast genomes for the greatest number of species, the phylogenetic tree of the Rhamnaceae was reconstructed. Phylica pubescens displayed a close phylogenetic relationship with Spyridium species. This study provides valuable information regarding the complete chloroplast genome of Phylica pubescens and its comparative analysis with other Rhamnaceae species. These findings enhance our knowledge of the evolution within the Rhamnaceae family and shed light on the relationships between Phylica pubescens and closely related taxa. [ABSTRACT FROM AUTHOR]

An accurate understanding of the elastostatic properties for flange-bolted joints is crucial in modeling the nonlinear dynamics. In this study, the elastostatics of the flange are investigated through finite element (FE) analysis and experimental test. It is shown that the axial stiffness exhibits bi-linear properties, and the flange appears axial-flexural coupling deformations under bending moments. Then, to understand the bi-linear axial stiffness properties and the influence of bolt preloads on axial and bending stiffnesses, the bolted T-stub joint is chosen as the object of study, and the relevant mechanical model is further presented based on linear elasticity. Meanwhile, the validity of the mechanical model is numerically verified. The analysis indicates that under tension and compression, the essence of the bi-linear axial stiffness is the differences in interface contact status, and the coupling deformations are induced by different tensile and compressive stiffnesses. In addition, both the tensile and bending stiffnesses increase with the increase of bolt preloads, while the effect of preloads on compressive stiffness is insignificant. • An equivalent mechanical model for the T-stub is presented to understand the elastostatics of flange-bolted joints. • The essence of the bi-linear axial stiffness properties are fully revealed. • The mechanisms of axial-flexural coupling deformations are investigated. • The influence of bolt preloads on axial and bending stiffnesses are discussed. [ABSTRACT FROM AUTHOR]

• The complete chloroplast genomes of 16 citrus species (include species of great economic importance) were de novo assembled, then several unique characters were identified. • To advance genetic improvement, the phylogenetic relationships of citrus species and the discrimination of subgenera must be clarified. • Herein, the comparative chloroplast genome analysis of citrus species was to address the challenges in determining phylogenetic relationships and discriminating citrus subgenera caused by species hybridization, polyembryony, and asexual reproduction. • The genus citrus was subdivided into seven subgenera based on phylogenetic analyses of the complete chloroplast genomes of citrus species: Poncirus, Fortunella, Papeda, Citron, Cephalocitrus, Aurantium, and sinocitrus. • This study may help with the identification, taxonomy, use, and evolution of citrus species. Citrus species are fruit trees with great economic value worldwide and have been domesticated and cultivated for several years. Although numerous phylogenetic taxonomy studies have been conducted since the establishment of the genus Citrus , the determination of phylogenetic relationships of Citrus species and the discrimination of Citrus subgenera face some challenges due to species hybridization, polyembryony, and asexual reproduction. In this study, the complete chloroplast genomes of 16 Citrus species were de novo assembled, then several unique characters were identified. For example, infA and rpl22 gene losses occurred in Citrus species; the trnQ -UUG gene may have played a significant role in the evolution of Citrus species; the rpoC1 gene in chloroplast genomes of Citrus species was under positive selection; and several highly variable loci (trnK -UUU– trnQ -UUG, atpF – atpH, trnG -GCC– trnfM -CAU, accD – psaI, petD – rpoA , and rpl32 – trnL -UAG) were found in the chloroplast genomes of the Citrus species. These variable loci could serve as potential markers for phylogenetic studies. The genus Citrus was subdivided into seven subgenera based on phylogenetic analyses of the complete chloroplast genomes of Citrus species: Poncirus, Fortunella, Papeda, Citron, Cephalocitrus, Aurantium , and Sinocitrus. This study may help with the identification, taxonomy, use, and evolution of Citrus species. [ABSTRACT FROM AUTHOR]

In this study, considering the elastoplastic behavior of contacting asperities on micro-scale and the contact pressure distribution of bolted joint interfaces on macro-scale, an improved contact stiffness model is presented. Firstly, the bolted T -stub joint is chosen as the object of study, and the distribution of normal contact load over the interface under preload conditions is studied. Then, combining the continuity, smoothness and monotonicity of the constitutive relations of normal contact load-deformation in three different regimes of plastic- elastoplastic-elastic of contacting asperities, the contact stiffness of individual asperity is analytically derived. Meanwhile, the relation between the distribution of contact stiffness and the distribution of normal contact load for bolted joint interfaces is determined based on fractal theory. The presented model overcomes the shortcomings of the contact stiffness without elastoplastic behavior obtained from the MB model and reveals the inhomogeneous distribution features of interfacial contact stiffness in bolted joints. Finally, the finite element (FE) analysis for flange-bolted joints incorporating the proposed model and the relevant experimental verification are performed. The results show that the average error of the first 4-order natural frequencies between the FE results and the experimental ones is only 0.72%, and the predicted results in frequency-domain are consistent with the measured ones, which illustrates that the proposed model can be used in interface modeling of jointed structures. [ABSTRACT FROM AUTHOR]

The shading treatment which decreases light intensity affects the ornamental characteristics in herbaceous peony (Paeonia lactiflora Pall.), including flower color, leaf shape and stem straightness. However, the morphological, microstructural and lignin-related responses of its stems to shading have not been systematically and deeply studied. Here, we focused on these responses to shading treatment in herbaceous peony stems. Morphological results showed that shading treatment significantly bended stems, decreased stem diameters, lightened stem weights and reduced stem strength. Microstructural observations demonstrated that shading treatment decreased vascular bundle number, xylem area, xylem ratio and secondary cell wall (SCW) thickness. Lignin-related analysis revealed that shading treatment markedly decreased lignin content in cell walls especially S-lignin and G-lignin, deposition in SCWs and related enzyme activities. Furthermore, transcriptomic analysis showed that shading treatment suppressed lignin-related processes, lignin biosynthetic pathway and lignin-related transcriptional activators. Collectively, shading treatment suppressed lignin biosynthesis and reduced lignin deposition in SCW, leading to undeveloped secondary xylem and bender stems. These findings provide a fundamental understanding of the morphological, microstructural and lignin-related responses of herbaceous peony stem to shading. • Shading treatment led to slender and bender stems in herbaceous peony. • Shading treatment inhibited xylem and SCW development, resulting in bender stems. • Shading treatment reduced lignin content, deposition, composition and related enzyme activities. • Shading treatment suppressed lignin biosynthesis and its transcriptional regulation. [ABSTRACT FROM AUTHOR]

Considering the non-uniformly distributed contact pressure, this study presents a new contact characteristic parameters (contact stiffness and damping) model for bolted joint interfaces. Firstly, to transform the contact pressure distribution into normal contact load distribution, the contact pressure distribution and its mathematical representation of single-bolted joint are studied. Subsequently, the relationships among contact stiffness distribution, contact damping distribution and normal contact load distribution are determined based on the improved MB model. It is found that the interfacial contact stiffness and damping exhibit significant inhomogeneous distributions. The proposed model overcomes the shortcomings of homogeneous distributions of contact stiffness and damping in bolted joints derived from previous models. In addition, the effects of bolt preload, tangential-to-normal contact load ratio and friction coefficient on the contact stiffness and damping are discussed in detail. Finally, the finite element (FE) analysis for beam lap structure with bolted joints incorporating the proposed model and the relevant experimental are performed to verify the validity of the modeling method. The results indicate that the proposed model can significantly improve the modeling accuracy of bolted joints. • A new contact characteristic parameters model for bolted joint interfaces is developed. • The inhomogeneous distribution characteristics of interfacial contact stiffness and damping are fully revealed. • The varying relations of contact stiffness and damping versus relevant parameters are discussed in detail. • The numerical results are entirely coincident with the experimental. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is a popular high-end cut flower, but stem bending caused by low stem strength severely decreases its quality. To enhance stem strength, the regulatory effects of exogenous silicon were investigated in P. lactiflora. The results showed that silicon application enhanced stem strength by increasing the thickness of secondary cell walls and the layers of thickened secondary cells. Moreover, more lignin accumulated, particularly G-lignin and S-lignin, and the activities of lignin biosynthetic enzymes increased with silicon application. In addition, based on transcriptome analysis, silicon application induced the expression of genes participating in lignin biosynthesis pathway. Among them, hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase gene (HCT1) was isolated from P. lactiflora and found to be mainly localized in the cytoplasm of cells. Overexpression of PlHCT1 increased the layers of thickened secondary cells and lignin accumulation in tobacco, resulting in enhanced stem strength and demonstrably straight stems. Finally, silicon content, lignin content and PlHCT1 expression in P. lactiflora cultivars with high stem strengths were totally higher than those in cultivars with low stem strengths. These results indicated that silicon application enhanced stem strength by promoting lignin accumulation in P. lactiflora , which has prospects for stem quality improvement in general. [Display omitted] • Silicon increased the net photosynthesis rate and SPAD value. • Silicon enhanced stem strength by promoting lignin accumulation. • Silicon increased lignin biosynthetic enzyme activities and gene expression. • HCT1 expression was induced and localized in the cytoplasm of cells. • Overexpression of HCT1 increased lignin, resulting in enhanced stem strength. [ABSTRACT FROM AUTHOR]

• This work presents a method for absolute flow velocity measurement in spectral domain optical coherence tomography (SDOCT). • The probe arm of SDOCT is mounted on a dividing head which can change the incident angle of the probe beam. • By rotating the dividing head and reading the scale, Doppler angle of flow can be achieved. • The method is demonstrated with capillary phantom and blood flows of chicken embryo in vivo. Abnormal blood flow in the early stage of embryonic heart can lead to cardiac defects. Thus, accurate flow measurement in the embryonic heart is important for related studies. Optical coherence tomography (OCT) is a noninvasive imaging approach which can provide flow velocity distribution information with high spatial and temporal resolution. However, OCT is only sensitive to velocity components parallel to the probing beam. To measure absolute flow velocity, additional information, such as Doppler angle, is required. Here, we propose a practical method to measure Doppler angle by introducing a dividing head to probe the arm of OCT. The incident angle of the probe beam can be controlled by rotating the dividing head. With the scale of the dividing head, rotating angle can be obtained. In each measurement, probe beam is adjusted to a proper angle by real time flow monitoring. Then, the probe beam is rotated perpendicularly to the flow velocity, i.e. Doppler angle is π/2 , and the Doppler angle can be calculated. This method is validated by capillary phantom. Last, blood flow in the early stage of chicken embryo is measured in vivo by the proposed method. [ABSTRACT FROM AUTHOR]

• A new pattern bundle with a smaller wire diameter of peripheral rods was proposed. • The comparative study between the new bundle and the conventional one was carried out by RANS-based CFD simulation. • The better flow and heat transfer performance was obtained for the new pattern bundle. In this paper, a new pattern bundle with a smaller wire diameter of peripheral rods was proposed. By decreasing the wire diameter of peripheral rods, the flow area of peripheral sub-channels is reduced diverting more coolant towards the central sub-channels. This would lead to a more uniform sub-channel temperatures distribution. To analyze the flow and heat transfer performance of the new bundle, the comparative study between the new bundle and conventional one was carried out by RANS-based CFD simulation. It was found that decreasing the partial wire diameters, the uniformity of coolant flow distribution is improved, resulting in a more homogeneous temperature distribution. The local transverse pressure difference characterizing global swirl motion is smaller, resulting in a weaker sweeping flow in peripheral sub-channels. Moreover, the obvious sweeping flow also could be observed in inter-connected sub-channels due to the smaller wire diameter of peripheral rods. At last, Nusselt number and friction factor are the parameters targeted for the investigation, and the results show that the thermal-hydraulics performance of the new bundle has been significantly improved. Through the research of this paper, the qualitative understanding of fuel assembly structure optimization could be provided for the core design in future. [ABSTRACT FROM AUTHOR]

The expanding process of turbulent separation bubble induced by a horn ice on the leading edge of an airfoil for business jet was investigated numerically with IDDES. Through comparing with the experiment results of critical stall condition, the fidelity of method for detailed simulation of ice-induced separation was verified firstly. Then the separation bubble under post-stall conditions was investigated in the aspects of both the features of averaged static flowfield and the behaviors of transient shear-layer vortices. The averaged results manifested that during the stall process, the bubble expanded with stretching and deformation for reattachment line and turbulence region were shifted towards trailing edge and spread continually. The corresponding extending and descending of pressure plateau with weak pressure gradient resulted in an early but mitigated stall pattern consequently. From the transient flowfield, it was observed that the entire evolution process of bubble was driven by the hairpin-type vortices generated from the shedding shear-layer with K-H instability. The propagation direction of these shear-layer vortices was affected by the entrainment of external flow. Under the post-stall condition, the motion of vortices towards the wall was delayed with the increasing of incidence and the interaction between vortices and wall was weakened correspondingly, which leaded the gradual decrease of reattachment effect and the continuous expanding of recirculation region. [ABSTRACT FROM AUTHOR]