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High-temperature fracture behavior of MnS inclusions based on GTN model

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Journal of Iron and Steel Research International 2019年第9期26卷 941-952页

作者： Xin-gang Liu Can Wang Qing-feng Deng bao-feng guo Key Laboratory of Advanced Forging and Stamping Technology and Science (Yanshan University) Ministry of Education of ChinaQinhuangdao 066004HebeiChina

The influence of the MnS plastic inclusion on the accumulation of internal damage was considered, and the Gurson– Tvergaard–Needleman (GTN) model was calibrated based on the finite element inverse method and image analysis method using ABAQUS and GTN models. The modified GTN damage model was used to simulate the initiation and propagation of cracks in an as-cast 304 stainless steel with MnS inclusions at 900 C. The simulation results agreed well with the experimental results, indicating that the model can be effectively applied to examine the high-temperature fracture behavior of MnS inclusions. The simulation and high-temperature tensile test results revealed that MnS inclusions increased the number of holes initiation and the probability of hole polymerization, reduced the crack propagation resistance, accelerated the occurrence of material fracture behavior, and were closely related to the stress state at high temperatures. When the stress triaxiality was low, the plastic strain in the metal matrix was high, and the MnS plastic inclusions accelerated the polymerization of the pores, making metal fracture failure more likely. On the other hand, when the stress triaxiality was high, the stress state in the metal matrix was biased to the tensile state, the plastic strain in the metal matrix was low, and the influence of MnS plastic inclusions on the fracture behavior was not evident.

关键词： MnS inclusion GTN model Tension High-temperature fracture behavior Crack initiation Crack propagation Stress

Formation Mechanism of Inclusion Defects in Large Forged Pieces

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Journal of Iron and Steel Research International 2016年第6期23卷 531-538页

作者： Rong-sheng QI Miao JIN Xin-gang LIU bao-feng guo Key Laboratory of Advanced Forging and Stamping Technology and Science of Ministry of Education Yanshan University

Nonmetallic inclusions mixed into large forged metal objects destroy the continuity in the metal and affect the quality of the forged *** on how inclusions affect the plastic deformation of a matrix shows the significance of the formation mechanism of inclusion *** upset forging,the nonlinear finite element model was shown to be appropriate for the ingot hot-forging process by comparing the results with experiments involving plastic and hard inclusions inserted into the forged *** high-temperature stress-strain curves of MnS plastic inclusions were obtained *** results show how,during upsetting,the morphology of MnS plastic inclusions varies from spherical to ellipsoidal,until finally becoming flat in *** larger the inclusion is,the larger the degree of deformation of the inclusion is,and large inclusions enhance the risk of the final product failing to pass inspection for inclusion *** significantly concentrates in the matrix near a hard *** the hard inclusion reaches a certain size,conical fractures form on both sides of the *** pass inclusion-flaw inspection and close hole defects to the extent possible,the flat-anvil upsetting is ***,the inclusiondeformation state obtained by finite element simulation is verified experimentally.

关键词： inclusion inspection anvil spherical destroy continuity forging finally verified ingot

Flow Stress Behaviors and Microstructure Evolution of 300M High Strength Steel under Isothermal Compression

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Journal of Iron and Steel Research International 2014年第12期21卷 1116-1123页

作者： Rong-sheng QI bao-feng guo Xin-gang LIU Miao JIN Key Laboratory of Advanced Forging & Stamping Technology and Science(Yanshan University) Ministry of Education of China

The compressive deformation behaviors of 300M high strength steel were investigated over a wide range of temperatures （850- 1200 C） and strain rates （0. 001- 10 s^- 1 ） on a Gleeble-3800 thermo-mechanical simulator. The measured flow stress was modified by the corrections of the friction and the temperature compensations, which nicely reflect negative effects of the friction and temperature on the flow stress. The corrected stress-strain curves were the dynamic recrystallization type on the conditions of higher deformation temperature and lower strain rate. Flow stress increases with the increase of strain rate at the same deformation temperature and strain. By contrast, flow stress decreases with the increase of temperature at the same strain rate and strain. Dependence of the peak stress on temperature and strain rate for 300M steel is described by means of the conventional hyperbolic sine equation. By re gression analysis, the activation energy （Q） in the whole range of deformation temperature is determined to be 367. 562 kJ/mol. The effects of the temperature and the strain rate on mierostructural evolution are obvious. With the increase of the deformation temperature and the decrease of the strain rate, the original austenite grain sizes of 300M steel increase. At the same time, the corrected flow stress curves more accurately determine the evolution of the microstrueture.

关键词： 300M high strength steel flow stress curve correction microstructural evolution

Is XMRV a causal virus for prostate cancer？

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Asian Journal of Andrology 2011年第5期13卷 698-701页

作者： Zhen-Zhen Zhang bao-feng guo Zhuang feng Ling Zhang Xue-Jian Zhao Department of Epidemiology Michigan State University East Lansing MI 48224 USA Research Center of Prostate Diseases Department of Reproductive Pathophysiology School of Basic Medicine Jilin University Changchun 130021 China Department of Surgery China-Japan Union Hospital Norman Bethune Medical School Jilin University Changchun 130031 China Department of Pathology Wayne State University Detroit MI 48201 USA

The potential association between xenotropic murine leukaemia virus-related gammaretrovirus （XMRV） and prostate cancer （PCa） has been documented since 2006, It is important for furthering our understanding of the biological mechanisms of PCa to ascertain whether this association is causal. To summarize the available information on the epidemiological and laboratory findings of the association, we conducted a literature search of the PubMed electronic database （from March 2006 to February 2011） to identify relevant published studies that examined the association between XMRV and PCa, Although several studies showed the positive association between XMRV and PCa, more recent studies did not support this conclusion, The positive findings might be due to contamination of human samples, Further studies are needed to clarify this association,

关键词： prostate cancer review XMRV

Prediction of Critical Conditions for Dynamic Recrystallization in 316LN Austenitic Steel

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Journal of Iron and Steel Research International 2016年第3期23卷 238-243页

作者： Xin-gang LIU Li-ge ZHANG Rong-sheng QI Lei CHEN Miao JIN bao-feng guo Key Laboratory of Advanced Forging & Stamping Technology and Science(Yanshan University) Ministry of Education of China Yanshan University Library Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

Hot compression experiments conducted on a Gleeble-3500thermo-mechanical simulator and metallographic observation tests were employed to study the critical conditions of dynamic recrystallization（DRX）of 316 LN austenitic stainless *** true stress-true strain curves of 316 LN were obtained at deformation temperatures ranging from 900℃to 1 200℃and strain rates ranging from 0.001s-1 to *** on the above tests,the critical conditions of DRX were determined and compared with those obtained from work-hardening theory and the Cingara-McQueen flow stress ***,the microstructure was observed to validate the calculated *** ratio of critical strain to peak strain（εc/εp）for 316 LN was determined,and the quantitative relationship between the critical strain and the deformation parameters of 316 LN was *** results demonstrated that the onset of DRX corresponds to the constant normalized strain hardening rate（Γ）,namely,the critical strain hardening rateΓcfor316LN is equal to 0.65.

关键词： 316LN austenitic stainless steel hot deformation dynamic recrystallization critical condition

Self-assembly of Amphiphilic Linear Diblock Rod-Coil Molecules by Hydrogen Bond and π-π Stacking Interactions

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Chinese Journal of Polymer Science 2016年第3期34卷 307-315页

作者： Ke-li Zhong Zhao-nian Chen bao-feng guo Ke-di Cai Yong-ri Liang 励建荣金龙一 College of Chemistry and Chemical Engineering Bohai University. Food Safety Key Lab of Liaoning Province. National & Local Joint Engineering Research Center of Storage Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products College of Materials Science & Engineering Beijing Institute of Petrochemical Technology Key Laboratory for Organism Resources of the Changbai Mountain and Functional Molecules Ministry of Education of China Department of Chemistry College of Science Yanbian University

Aromatic amphiphilic molecules（1） consisting of three biphenyl groups linked together with ether bonds as a rigid rod segment and poly（ethylene oxide） with the number of repeating units of 17 as a coil segment were synthesized, and their self-assembly behavior in the bulk state and aqueous solution was investigated. In bulk, molecules 1 self-assembled into 1-D lamellar structure in the solid state or smectic A phase in the liquid crystalline phase via the cooperative effects of ？-？ stacking, micro-phase separation and hydrogen bond interactions. In dilute aqueous solutions, molecules 1 were observed to selfassemble into cylindrical micelles owned uniform diameter and length of hundreds of nanometers.

关键词： Rod-coil Self-assembly Smectic A phase Cylindrical micelles SAXS

Plasmid-based Stat3 siRNA delivered by hydroxyapatite nanoparticles suppresses mouse prostate tumour growth in vivo

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Asian Journal of Andrology 2011年第3期13卷 481-486,514页

作者： Zuo-Wen Liang bao-feng guo Yang Li Xiao-Jie Li Xin Li Li-Jing Zhao Li-Fang Gao Hao Yu Xue-Jian Zhao Ling Zhang bao-Xue Yang Prostate Diseases Prevention and Treatment Research Centre and Department of Pathophysiology Norman Bethune Medical School Jilin University Changchun 130021 China Department of Emergency Medicine China-Japan Union Hospital of Jilin University Changchun 130033 China Department of Pharmacology School of Basic Medical Sciences Peking University Beijing 100191 China

DNA vector-based Stat3-specific RNA interference （si-Stat3） blocks Stat3 signalling and inhibits prostate tumour growth. However, the antitumour activity depends on the efficient delivery of si-Stat3. The effects on the growth of mouse prostate cancer cells of si-Stat3 delivered by hydroxyapatite were determined in this study. RM-1 tumour blocks were transplanted into C57BIJ6 mice. CaCl2-modified hydroxyapatite carrying si-Stat3 plasmids were injected into tumours, and tumour growth and histology were determined. The expression levels of Star3, pTyr-Stat3, Bcl-2, Bax, Caspase3, VEGFand cyclin D1 were measured by western blot analysis. Amounts of apoptosis in cancer cells were analysed with immunohistochemistry and the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling （TUNEL） assay. The results showed that hydroxyapatite-delivered si-Stat3 significantly suppressed tumour growth up to 74% （P〈0.01）. Stat3 expression was dramatically downregulated in the tumours. The immunohistochemistry and TUNEL results showed that si-Stat3-induced apoptosis （up to 42%, P〈0.01）. The Stat3 downstream genes Bcl-2, VEGFand cyclin DI were also strongly downregulated in the tumour tissues that also displayed significant increases in Bax expression and Caspase3 activity. These results suggest that hydroxyapatite can be used for the in vivo delivery of plasmid-based siRNAs into tumours.

关键词： apoptosis hydroxyapatite prostate cancer RNA interference Star3

;~lasmid-based Survivin shRNA and GRIM-19 carried by attenuated Salmonella suppresses tumor cell growth

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Asian Journal of Andrology 2012年第4期14卷 536-545页

作者： Yan-Bo Liu Ling Zhang Ya-Xiong guo Li-Fang Gao Xi-Chun Liu Li-Juan Zhao bao-feng guo Li-Jing Zhao Xue-Jian Zhao De-Qi Xu Prostate Diseases Prevention and Treatment Research Centre and Department of Pathophysiology Norman Bethune Medical SchoolJilin UniversityChangchun 130021 China Department of Pathophysiology School of Bacic MedicineBeihua UniversityJilin132013China Urology center The First Hospital of Jilin University Changchun 130021China New Vaccine National Engineering Research Center Beijing 100176China

Persistent activation of Survivin and its overexpression contribute to the formation, progression and metastasis of several different tumor types. Therefore, Survivin is an ideal target for RNA interference mediated-growth inhibition. Blockade of Survivin using specific short hairpin RNAs （shRNA） can significantly reduce prostate tumor growth. RNA interference does not fully ablate target gene expression, owing to the idiosyncrasies associated with shRNAs and their targets. To enhance the therapeutic efficacy of Survivin-specific shRNA, we employed a combinatorial expression of Survivin-specific shRNA and gene associated with retinoid-interferon-induced mortality-19 （GRIM-19）. Then, the GRIM-19 coding sequences and Survivin-specific shRNAs were used to create a dual expression plasmid vector and were carried by an attenuated strain of Salmonella enteric serovar typhimurium （S. typhimurium） to treat prostate cancer in vitro and in vivo. We found that the co-expressed Survivin-specific shRNA and GRIM-19 synergistically and more effectively inhibited prostate tumor proliferation and survival, when compared with treatment with either single agent alone in vitroand in vivo. This study has provided a novel cancer gene therapeutic approach for prostate cancer.

关键词： GRIM-19 prostate cancer RNAi Salmonella enterica serovar typhimurium Survivin tumor cell growth

Comparative study on the stem cell phenotypes of C6 cells under different culture conditions

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Chinese Medical Journal 2011年第19期124卷 3118-3126页

作者： ZHANG Suo-jun YE Fei XIE Rui-fan HU feng WANG bao-feng WAN feng guo Dong-sheng LEI Ting Department of Neurosurgery and Neuro-Oncology Molecular Biology Laboratory Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan Hubei 430030 China

Background Glioma stem cell （GSC） hypothesis posits that a subpopulation of cells within gliomas have true clonogenic and tumorigenic potential. Significantly, a more controversial correlate to GSC is that cells in different culture conditions might display distinct stem cell properties. Considering these possibilities, we applied an approach comparing stem cell characteristics of C6 glioma cells under different culture *** C6 cells were cultured under three different growth conditions, i.e., adherent growth in conventional 10% serum medium, non-adherent spheres growth in serum-free medium, as well as adherent growth on laminin-coated flask in serum-free medium. Growth characteristics were detected contrastively through neurosphere formation assay and cell cycle analysis. Markers were determined by immunofluorescence, relative-quantitative reverse transcription （RT）-PCR,Western blotting and flow cytometry. Side population cells were analyzed via flow cytometry. Tumor models were detected by magnetic resonance imaging and hematoxylin ＆ eosin staining. Data analyses were performed with SPSS software （17.0）.Results C6 cells （C6-Adh, C6-SC-Sph and C6-SC-Adh） showed distinctive growth patterns and proliferation *** to suspending C6-SC-Sph, adherent C6-Adh and C6-SC-Adh displayed higher growth ratio. C6-SC-Sph and C6-SC-Adh showed enhanced capability of neurosphere formation and self-renewal. High side population ratio was detected in C6-SC-Sph and C6-SC-Adh. CD133 was not detected in all three kinds of cells. Conversely, Nestin and β-Ⅲ-tubulin were demonstrated positive, nonetheless with no statistical significance （P 〉0.05）. Interestingly, lower expression of glial fibrillary acidic protein was demonstrated in C6-SC-Sph and C6-SC-Adh. C6-Adh, C6-SC-Sph and C6-SC-Adh were all displayed in situ oncogenicity, while statistical difference of survival time was not *** C6 glioma cell line is endowed with some GSC phenotypes that

关键词： C6 glioma stem cell neurosphere CD133 side population laminin