The Effect of Cr on Phase Transformation Behavior of Austenite in Fe-20Mn-9Al-1.2C-xCr Low-density Steels During Isothermal Aging

Jianlei Zhang,Yueshan Jiang,Conghui Hu,Gang Ji,Changjiang Song,Qijie Zhai 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11

The influence of Cr on the microstructural evolution of austenite in Fe-20Mn-9Al-1.2C-xCr (wt%, x = 0, 3 and 6) low-densitysteels during isothermal aging at 650 °C for various durations was systematically investigated. With the isothermal agingprocessed, the 0Cr and 3Cr samples underwent the divorced eutectoid transformation followed by the eutectoid transformation,while only the eutectoid transformation was observed in the 6Cr sample. Meanwhile, increasing Cr content changedthe eutectoid transformation products from ferrite + κ-carbide in the 0Cr sample to ferrite + κ-carbide + M23C6carbide in the3Cr sample, and to ferrite + M7C3carbide in the 6Cr sample. The Cr addition significantly increased the A1 temperature (655°C) of the 0Cr sample to 712 °C of the 3Cr sample, and to 841 °C of the 6Cr sample. As a result, the temperature differencebetween the A1 temperature and experimental phase transformation temperature (650 °C) was enlarged, which provided agreater driving force for the eutectoid transformation and accelerated the transformation rate of eutectoid transformation. Inaddition, the Cr addition had a significant effect on the diffusion of constituent elements, decreased the interlayer spacingof pearlite structure from 625 ± 30 nm in the 0Cr sample to 385 ± 25 nm in the 3Cr sample, and to 150 ± 20 nm in the 6Crsample, refining the eutectoid structure. These findings revealed the mechanism regarding the effect of Cr addition on theeutectoid transformation of austenite, offering valuable insights into the microstructure design of high-performance lowdensitysteels.

High-Strength Model Material Production for Structural Plane Replica and Its Shear Testing

Feng Ji,Changjiang Liu,Yu Zhang,Luobing Zheng,Kai Pan,Xun Tan 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.1

Shear strength parameters (c, φ) of a structural plane are the key factors for the stability assessment of rock masses. The shear strength parameters are obtained by a structure plane shear test carried out in laboratory. However, it is difficult to obtain test samples with the same surface morphology and to remove the effect of surface irregularity from test results. Based on the similarity principle and orthogonal test, this paper presents a new model preparation method for structural planes using a high-strength mold mixture material. Firstly, the original morphology of the structural plane is recorded by in situ measurement using a laser device and then the mold of the structural plane is reproduced using a 3D printer. Subsequently, a mix proportion test of the high-strength mold material is conducted using the orthogonal test, and the model of the structural plane is prepared by pouring this high-strength mixture material into the 3D mold. Ultimately, the shear strength parameters of this high-strength structural plane replica are obtained using a shear box test in the laboratory. The proposed method has particular advantages such as the preparation of multiple replicas for structure planes and the ability to obtain repeatable results.

Comparative Study of the marR Genes within the Family Enterobacteriaceae

Dan Wang,Changjiang Guo,Longjiang Gu,Xiaohui Zhang 한국미생물학회 2014 The journal of microbiology Vol.52 No.6

marR genes are members of an ancient family originallyidentified in Escherichia coli. This family is widely distributedin archaea and bacteria. Homologues of this family have aconserved winged helix fold. MarR proteins are involved innon-specific resistance systems conferring resistance to multipleantibiotics. Extensive studies have shown the importanceof MarR proteins in physiology and pathogenicity inEnterobacteria, but little is known about their origin or evolution. In this study, all the marR genes in 43 enterobacterialgenomes representing 14 genera were identified, and the phylogeneticrelationships and genetic parameters were analyzed. Several major findings were made. Three conserved marRgenes originated earlier than Enterobacteriaceae and a genelossevent was found to have taken place in Yersinia pestisAntiqua. Three functional genes, rovA, hor, and slyA, werefound to be clear orthologs among Enterobacteriaceae. Thecopy number of marR genes in Enterobacteriaceae was foundto vary from 2 to 11. These marR genes exhibited a faster rateof nucleotide substitution than housekeeping genes did. Specifically, the regions of marR domain were found to besubject to strong purifying selection. The phylogenetic relationshipand genetic parameter analyses were consistentwith conservation and specificity of marR genes. These dualcharacters helped MarR to maintain a conserved bindingmotif and variable C-terminus, which are important to adaptiveresponses to a number of external stimuli in Enterobacteriaceae.

Research on Stratified Multi-objective Optimization Algorithm in Wireless Networks

Tu Xionggang,Chen Jun,Zhang Changjiang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.4

Due to the cost, reliability and quality of communication equilibrium of the traditional FM radio network optimization algorithms during the construction , hierarchical multi-objective optimization algorithm is put forth.First, increasee FM wireless networks mobile node and select new-adding link waypoints’ optimal vector set, then design a hierarchical optimization model, and then use hierarchical multi-objective optimization algorithm to solve the problems of VHF wireless networks.Finally, compared simulation experiment of stratified multi-objective optimization algorithm and Glid algorithm and violent search algorithm is conducted, and the experiment shows that: stratified multi-objective optimization algorithm is smaller than traditional optimization algorithms in areas such in the network nodes, the average communication jump and the average attenuation of communication after running 50 times, i.e. lower cost, better network reliability and communication quality.

Improvement on Mechanical Properties of a bcc Matrix Al8(FeCuCrMn)92 High-Entropy Alloy by Phase Modulation of Interstitial Carbon Element

Conghui Hu,Jianlei Zhang,Yunhu Zhang,Ke Han,Changjiang Song,Qijie Zhai 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

High-entropy alloys (HEAs) are novel multi-element alloys based on five or more constituent elements in a range of 5–35 at%. Here we present a method to improve strength of a body-centered cubic (bcc) matrix HEA without loss of ductility. Theimprovement was achieved by phase modulation combined other strengthening effect of interstitial carbon addition. Carbonaddition can enhance strength and retain good ductility in some steels because carbon increases the volume fraction offace-centered cubic (fcc) phase. We used the same principle to design and fabricate a set of Al8(FeCuCrMn)92Cx (x = 0, 1,2, 3, 4 at%) HEAs under near-rapid solidification. Our results showed that carbon addition modulated constituent phases byincreasing the volume fraction of fcc phase and carbides. As a result, addition of carbon increased yield strength of this bccmatrix HEA. But the ductility decreased, especially when carbon content was higher than 3 at%, which was ascribed to unevendistribution of Cu-rich fcc phase and carbides precipitated in bcc phase region. After annealing at 1173 K for 2 h, additionof 1 at% carbon improved yield strength without compressive fracture. It demonstrated that a proper carbon content additionwith annealing can enhance the yield strength without loss of ductility for this bcc matrix HEA. Thus, interstitial carbon additionis a meaningful method to improve the mechanical properties by phase modulation combined other strengthening effect.

Elevated Expression of RIOK1 Is Correlated with Breast Cancer Hormone Receptor Status and Promotes Cancer Progression

Zhiqi Huang,Xingyu Li,Tian Xie,Changjiang Gu,Kan Ni,Qingqing Yin,Xiaolei Cao,Chunhui Zhang 대한암학회 2020 Cancer Research and Treatment Vol.52 No.4

Purpose RIOK1 has been proved to play an important role in cancer cell proliferation and migration in various types of cancers—such as colorectal and gastric cancers. However, the expression of RIOK1 in breast cancer (BC) and the relationship between RIOK1 expression and the development of BC are not well characterized. In this study, we assessed the expression of RIOK1 in BC and evaluated the mechanisms underlying its biological function in this disease context. Materials and Methods We used immunohistochemistry, western blot and quantitative real-time polymerase chain reaction to evaluate the expression of RIOK1 in BC patients. Then, knockdown or overexpression of RIOK1 were used to evaluate the effect on BC cells in vitro and in vivo. Finally, we predicted miR-204-5p could be a potential regulator of RIOK1. Results We found that the expression levels of RIOK1 were significantly higher in hormone receptor (HR)–negative BC patients and was associated with tumor grades (p=0.010) and p53 expression (p=0.008) and survival duration (p=0.011). Kaplan-Meier analysis suggested a tendency for the poor prognosis. In vitro, knockdown of RIOK1 could inhibit proliferation, invasion, and induced apoptosis in HR-negative BC cells and inhibited tumorigenesis in vivo, while overexpression of RIOK1 promoted HR-positive tumor progression. MiR-204-5p could regulate RIOK1 expression and be involved in BC progression. Conclusion These findings indicate that RIOK1 expression could be a biomarker of HR-negative BC, and it may serve as an effective prognostic indicator and promote BC progression.

Effect of Sea Buckthorn Leaves on Inosine Monophosphate and Adenylosuccinatelyase Gene Expression in Broilers during Heat Stress

Zhao, Wei,Chen, Xin,Yan, Changjiang,Liu, Hongnan,Zhang, Zhihong,Wang, Pengzu,Su, Jie,Li, Yao Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.1

The trial was conducted to evaluate the effects of sea buckthorn leaves (SBL) on meat flavor in broilers during heat stress. A total 360 one-day-old Arbor Acre (AA) broilers (male) were randomly allotted to 4 treatments with 6 replicates pens pretreatment and 15 birds per pen. The control group was fed a basal diet, the experimental group I, II and III were fed the basal diet supplemented with 0.25%, 0.5%, 1% SBL, respectively. During the 4th week, broilers were exposed to heat stress conditions ($36{\pm}2^{\circ}C$), after which, muscle and liver samples were collected. High performance liquid chromatography (HPLC) was performed to measure the content of inosine monophosphate (IMP); Real-Time PCR was performed to determine the expression of the ADSL gene. The results showed that the content of breast muscle IMP of group I, II and III was significantly increased 68%, 102% and 103% (p<0.01) compared with the control, respectively; the content of thigh muscle IMP of group II and III was significantly increased 56% and 58% (p<0.01), respectively. Additionally, ADSL mRNA expression in group I, II and III was increased significantly 80%, 65% and 49% (p<0.01) compared with the control, respectively. The content of IMP and expression of ADSL mRNA were increased by basal diet supplemented with SBL, therefore, the decrease of meat flavor caused by heat stress was relieved.