Nucleotide Variation in the NCED3 Region of Arabidopsis thaliana and its Association Study with Abscisic Acid Content under Drought Stress

Drought tolerance is a comprehensive quantitative trait that is being understood further at the molecular genetic level. Abscisic acid （ABA） is the main drought-induced hormone that regulates the expression of many genes related to drought responses. 9-cis-epoxycarotenoid dioxygenase （NCED3） is thought to be a key enzyme in ABA biosynthesis. In this paper, we measured the ABA content increase under drought stress, and sequenced and compared the sequence of AtNCED3 among 22 Arabidopsis thaliana accessions. The results showed that the fold of ABA content increase under drought stress was highly variable among these accessions. High density single nucleotide polymorphism （SNP） and insertion/deletion （indel） were found in the AtNCED3 region, on average one SNP per 87.4 bp and one indel per 502 bp. Nucleotide diversity was significantly lower in the coding region than that in non-coding regions. The results of an association study with ANOVA analysis suggested that the 274th site （P←→S） and the 327th site （P←→R） amino acid variations might be the cause of ABA content increase of 163av accession under drought stress.

Cloning and Expression Analysis of Rice Sucrose Transporter Genes OsSUT2M and OsSUT5Z

Two sucrose transporter （SUT） cDNAs, OsSUT2M and OsSUT5Z, were isolated from rice （Oryza sativa L.） by reverse transcription polymerase chain reaction （RT-PCR）. Sequencing results indicate they are 1 531 bp and 1 635 bp in length including complete open reading frame 1 506bp and 1 608 bp, which encode 502 amino acids and 536 amino acids, respectively. The TopPred program suggested that both sucrose transporter proteins, OsSUT2M and OsSUT5Z, consist of potentially 12 transmembrane domains. Semi-quantitative RT-PCR was carried out to investigate the gene expression patterns of OsSUT2M and OsSUT5Z. In vegetative organs, transcripts of OsSUT2M were higher in source leaf blades than in other organs at the same development stage, whereas transcripts of OsSUT5Z were less traceable in all organs investigated. In reproductive organs, both transcripts of these two genes were high in panicles from the booting stage to 7 days after flowering （DAF） and then sharply declined. The potential physiology functions of these two sucrose transporters are discussed.

Cell-wall Invertases from Rice are Differentially Expressed in Caryopsis during the Grain Filling Stage

Cell-wall invertase plays an important role in sucrose partitioning between source and sink organs in higher plants. To investigate the role of cell-wall invertases for seed development in rice （Oryza sativa L.）, cDNAs of three putative cell- wall invertase genes OsCIN1, OsCIN2 and OsCIN3 were isolated. Semi-quantitative reverse transcription-polymerase chain reaction analysis revealed different expression patterns of the three genes in various rice tissues/organs. In developing caryopses, they exhibited similar temporal expression patterns, expressed highly at the early and middle grain filling stages and gradually declined to low levels afterward. However, the spatial expression patterns of them were very different, with OsCIN1 primarily expressed in the caryopsis coat, OsCIN2 in embryo and endosperm, and OsCIN3 in embryo. Further RNA in situ hybridization analysis revealed that a strong signal of OsCIN2 mRNA was detected in the vascular parenchyma surrounding the xylem of the chalazal vein and the aleurone layer, whereas OsCIN3 transcript was strongly detected in the vascular parenchyma surrounding the phloem of the chalazal vein, cross-cells, the aleurone layer and the nuceUar tissue. These data indicate that the three cell-wall invertase genes play complementary/synergetic roles in assimilate unloading during the grain filling stage. In addition, the cell type-specific expression patterns of OsCIN3 in source leaf blades and anthers were also investigated, and its corresponding physiological roles were discussed.

Fatigue-creep interaction based on continuum damage mechanics for AISI H13 hot work tool steel at elevated temperatures

AISI H13 （4Cr5MoSiV1） is one of the commonly used materials for extrusion tool, and it suffers from fatigue-creep damage during the hot extrusion process. Stress-controlled fatigue and creep-fatigue interaction tests were carried out at 500℃ to investigate its damage evolution. The accumulated plastic strain was selected to define the damage variable due to its clear physical meaning. A new fatigue-creep interaction damage model was proposed on the basis of continuum damage mechanics. A new equivalent impulse density for fatigue-creep tests was proposed to incorporate the holding time effect by transforming creep impulse density into fatigue impulse density. The experimental results indicated that the damage model is able to describe the damage evolution under these working conditions.

Curvature and Residual Stress Analysis in Rotational Leveling of Bars

Leveling process plays an important role in delivering the desired material properties and product standards.An analytical method for the rotational leveling process of bars was presented.First,each cross section of the bar in the leveling area was discretized with the roller gap-curvature relations established in both planes XYand XZ.Second,a numerical procedure with two steps was developed to simulate both pressing and leveling processes.This approach can be easily implemented to produce simulation results of the curvature and trajectory distributions during the leveling process,as well as the bending and residual stresses.It is found that curvature and trajectory distributions follow a sine-shape due to the characteristic of rotational movement,which also results in a helical pattern of residual stress after leveling.Based on the results obtained,it is also observed that the rotational movement is beneficial for adding the number of bending cycle.This is the reason why there are only a few pairs of rollers on the bar leveler.

Augmented reality(AR)and fracture mapping model on middle-aged femoral neck fracture:A proof-of-concept towards interactive visualization

A thorough understanding of the fracture characteristics can assist the decision-making process for surgery.This study aimed to characterize the femoral neck fractures among middle-aged patients and illustrated a biomedical visualization method using a fracture mapping model and augmented reality.We collected plain radiography and computed tomography(CT)data from 156 adult patients with a femoral neck fracture.The descriptive study showed that Type I and Type II fractures accounted for 8(5%)and 64(41%)cases.In comparison,Type IV fractures accounted for 44(28%)and 40(25%)cases according to the Garden classification.Comminuted fractures and cortical defects were identified in 14.74%and 29.49%of the cases.A fracture mapping model was reconstructed based on the CT data and demonstrated the location and distribution of the major fracture lines surrounding the head-neck junction.We also illustrated the application of augmented reality technology to visualize and interact with the patient-specific fracture model and the fracture mapping model that facilitated education,training,and surgical planning.Future studies may consider mapping other biomechanical data,such as joint loading and stress distribution,and exploring artificial intelligence via deep reinforcement learning for computer-aided fracture reduction and procedure planning.