Investigating the effects of confining pressure on graphite material failure modes and strength criteria

Yi Yanan,Liu Guangyan,Xing Tongzhen,Lin Guang,Sun Libin,Shi Li,Ma Shaopeng 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7

As a critical material in very/high-temperature gas-cooled reactors, graphite material directly affects the safety of the reactor core structures. Owing to the complex structures of graphite material in reactors, the material typically undergoes complex stress states. It is, therefore, necessary to study its mechanical properties, failure modes, and strength criteria under complex stress states so as to provide guidance for the core structure design. In this study, compressive failure tests were performed for graphite material under the condition of different confining pressures, and the effects of confining pressure on the triaxial compressive strength and Young's modulus of graphite material were studied. More specifically, graphite material based on the fracture surfaces and fracture angles, the graphite specimens were found to exhibit four types of failure modes, i.e., tension failure, shear-tension failure, tension-shear failure and shear failure, with increasing confining pressure. In addition, the Mohr strength envelope of the graphite material was obtained, and different strength criteria were compared. It showed that the parabolic MohrCoulomb criterion is more suitable for the strength evaluation for the graphite material.

Study on failure mechanism of line contact structures of nuclear graphite

Jia Shigang,Yi Yanan,Wang Lu,Liu Guangyan,Ma Qinwei,Sun Libin,Shi Li,Ma Shaopeng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

Line contact structures, such as the contact between graphite brick and graphite tenon, widely exist in high-temperature gas-cooled reactors. Due to the stress concentration effect, the line contact area is one of the dangerous positions prone to failure in the nuclear reactor core. In this paper, the failure mechanism of line contact structures composed of IG11 nuclear graphite column and brick were investigated by means of experiment and finite element simulation. It was found that the failure process mainly includes three stages: firstly, the damage accumulation in nuclear graphite material led to the characteristic yielding of the line contact structure, but no macroscopic failure can be observed at this stage; secondly, the stresses near the contact area met Mohr failure criterion, and a crack initiated and propagated laterally in the contact zone, that is, local macroscopic failure occurred at this stage; finally, a second crack initiated in the contact area and developed in to a Y-shape, resulting in the final failure of the structure. This study lays a foundation for the structural design and safety assessment of hightemperature gas-cooled reactors

Experimental study on RC beams externally bonded by CFRP sheets with and without end self-locking

Chaoyang Zhou,Yanan Yu,Chengfeng Zhou,Xuejun He,Yi Wang 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.48 No.5

To avoid debonding failure, a novel type of hybrid anchorage (HA) is proposed in this study that uses a slotted plate to lock the ends of the fiber-reinforced polymer (FRP) sheet in addition to the usual bonding over the substrate of the strengthened member. An experimental investigation was performed on three groups of RC beams, which differed from one another in either concrete strength or steel reinforcement ratio. The test results indicate that the end self-locking of the CFRP sheet can improve the failure ductility, ultimate capacity of the beams and its utilization ratio. Although intermediate debonding occurred in all the strengthened beams, it was not a fatal mode of failure for the three specimens with end anchorage. Among them, FRP rupture occurred in the beam with higher concrete strength and lower steel reinforcement ratio, whereas the other two failed by concrete crushing. The beam strengthened by HA obtained a relatively high percentage of increase in ultimate capacity when the rebar ratio or concrete strength decreased. The expressions in the literature were inspected to calculate the critical loads at intermediate debonding, FRP rupturing and concrete crushing after debonding for the strengthened beam. Then, the necessity of further research is addressed.

Temperature dependent development of black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae) from Yangtze River Delta region of China

Wang Yinghui,Zhang Yanan,Wang Jiangfeng,Kang Chengtao,Hu Gengwang,Guo Yi,Chen Jie,Yang Lijun,Wang Yu 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.4

The black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), isomnivorous andwidely distributed in the world. Black soldier flies usually colonize corpse at a relatively late stage and have a longer developmental time compared to other flies. It can serve as a good supplementary indicator for estimating a longer minimum postmortem interval (PMI min ) in forensic investigations. In this paper, the development of H. illucens was investigated at six constant temperatures between 19 and 34 ◦ C. Under temperatures of 19, 22, 25, 28, 31, and 34 ◦ C, the mean developmental time from eggs to adults was 90.96, 58.29, 54.61, 42.33, 32.33 and 34.52 days, respectively. Developmental time and accumulated degree days results were used to construct thermal sum mation model and isomorphen diagram. The calculated values of lower developmental thresholds and thermal summation constant estimated by a linear model were 11.88 ◦ C and 650.89 degree days, respectively. Through a nonlinear model, the upper lethal developmental threshold temperature, intrinsic optimum temperature and lower developmental thresholds were estimated to be 35.18, 20.50 and 13.17 ◦ C, respectively. A growth curve, an equation and isomegalen diagram based on them show the relationship between developmental time and larval body length. The larval body length increased with increased developmental time and eventually pla teaued, revealing an S-shape growth curve. These results provide important basic developmental data for H. illucens, which can be used to estimate the PMI min .

Intrapuparial development and age estimation of Sarcophaga peregrina (Diptera: Sarcophagidae) for postmortem interval estimation

Li Liangliang,Zhang Yanan,Chen Yang,Guo Yi,Wang Yinghui,Hu Gengwang,Kang Chengtao,Jiangfeng Wang,Wang Yu 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2

Sarcophaga peregrina Robineau-Desvoidy, 1830 (Diptera: Sarcophagidae) is a widely distributed species in the Palearctic, Oriental and Australian regions. Numerous studies and case reports have confirmed the value of this species in forensic investigations, but methods for estimating the age of the intrapuparial period of this species are lacking. In this study, S. peregrina pupae were sampled at 16 ◦ C, 19 ◦ C, 22 ◦ C, 25 ◦ C, 28 ◦ C, 31 ◦ C, and 34 ◦ C. Morphological changes within the puparium were observed under a stereomicroscope. The results of the study showed that S. peregrina could complete its intrapuparial development at each of the seven tested constant temperatures. As the temperature increased, the average minimum duration of the intrapuparial period of S. peregrina decreased from 706.7 ± 28.1 h at 16 ◦ C to 170.7 ± 4.6 h at 34 ◦ C. The intrapuparial morphological changes of S. peregrina can be divided into 12 sub-stages. While some structures such as the compound eyes, mouthparts, antennae, thorax, legs, wings, and abdomen can be used individually to estimate intrapuparial age, we observed all these structures with local magnification photographs and classified the developmental process of these structures into 6–11 stages. The time range for the appearance of each sub-stage or structure was recorded in detail. The results of this study provide important basic data for estimating the minimum postmortem interval using the intrapuparial morphology of S. peregrina.

A novel statistical framework to account for climate model dependence and to test non-exclusive hypotheses: Application to Arctic sea ice

Roman Olson,Soon-Il An,Yanan Fan,Won Chang,Jason P. Evans,June-Yi Lee 한국기상학회 2019 한국기상학회 학술대회 논문집 Vol.2019 No.10

Protocadherin alpha 3 inhibits lung squamous cell carcinoma metastasis and epithelial-mesenchymal transition

Tao Yu,Fei Liu,Chang Liu,Yongyu Liu,Jianhui Jia,Yanan Liu,Yi Ren 한국유전학회 2022 Genes & Genomics Vol.44 No.2

Background: Lung squamous cell carcinoma (LUSC) is associated with poor clinical prognosis and lacks available targeted therapy. Given that the major threat of cancer is metastasis, delineation of the molecular mechanism underlying it would help devise therapeutic strategies. Objective: To investigate the functional role of protocadherin alpha 3 (PCDHA3) in LUSC, as well as investigate the underlying molecular mechanism. Methods: Data for PCDHA3 expression and clinical information in The Cancer Genome Atlas (TCGA) were extracted and analyzed in the UALCAN platform. Expression levels of PCDHA3 in LUSC cell lines were analyzed via RT-PCR and western blot. Overexpression of PCDHA3 was conducted via plasmid transfection. CCK-8 and cell cycle assays were utilized to investigate effect of PCDHA3 on cell proliferation. Transwell assay was used to detect migration and invasion. The underlying mechanism was demonstrated via western blot analysis. Results: Our data indicate that PCDHA3 was low expressed in three kinds of LUSC cell lines and best in H520 cells. Furthermore, overexpression of PCDHA3 could significantly impair LUSC cells proliferation, invasion and migration. Moreover, PCHDA3 repressed the biomarkers of mesenchymal (N-cadherin, fibronectin and vimentin) and increased expression of epithelial markers (E-cadherin and α-catenin). On the other hand, PCDHA3 overexpression partially blocked epithelial-mesenchymal transition. Conclusions: PCDHA3 suppressed the LUSC cells proliferation, invasion and migration via inhibiting the expression of EMT signatures, suggesting that PCDHA3 could serve as a valuable therapeutic target for LUSC therapy.

Cloning and Biochemical Characterization of a Hyaluronate Lyase from Bacillus sp. CQMU-D

Wang Lu,Liu Qianqian,Gong Xue,Jian Wenwen,Cui Yihong,Jia Qianying,Zhang Jibei,Zhang Yi,Guo Yanan,Lu He,Tu Zeng 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.2

Hyaluronidase (HAase) can enhance drug diffusion and dissipate edema by degrading hyaluronic acid (HA) in the extracellular matrix into unsaturated HA oligosaccharides in mammalian tissues. Microorganisms are recognized as valuable sources of HAase. In this study, a new hyaluronate lyase (HAaseD) from Bacillus sp. CQMU-D was expressed in Escherichia coli BL21, purified, and characterized. The results showed that HAaseD belonged to the polysaccharide lyase (PL) 8 family and had a molecular weight of 123 kDa. HAaseD could degrade chondroitin sulfate (CS) -A, CS-B, CSC, and HA, with the highest activity toward HA. The optimum temperature and pH value of HAaseD were 40°C and 7.0, respectively. In addition, HAaseD retained stability in an alkaline environment and displayed higher activity with appropriate concentrations of metal ions. Moreover, HAaseD was an endolytic hyaluronate lyase that could degrade HA to produce unsaturated HA oligosaccharides. Together, our findings indicate that HAaseD from Bacillus sp. CQMU-D is a new hyaluronate lyase and with excellent potential for application in industrial production.