Dynamic Recrystallization Mechanism and Precipitation Behavior of Mg-6Gd-3Y-3Sm-0.5Zr Alloy During Hot Compression

Miaomiao Li,Miaomiao Li,Dening Zou,Yunong Li,Libo Tong1 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

904L super austenitic stainless steel is prone to harmful secondary phase precipitation, which reduces corrosion resistance. The cooling rate during the solidification of steel is one of the critical factors affecting the precipitation of brittle phases instainless steel metals. In this paper, the effect of the cooling rates (6, 50, 100, 500, and 1000 °C min−1) on the initial corrosionbehavior of 904L steel in a simulated flue gas desulfurization (FGD) solution was studied by electrochemical measurementsand microscopic morphology observation. The results show that as the cooling rates increases, the primary solidification temperatureand the secondary dendrite arm spacing decrease. The precipitated phase in the steel is a σ-phase mainly distributedinterdendrites and forms zones of chromium and molybdenum depletion, reducing pitting resistance. With the increase in thecooling rate, the corrosion resistance increases first and then decreases, and reaches the maximum at 100 °C min−1. At thesame time, different cooling rates result in different contents of Cr and Mo in σ phase. At 100 °C min−1, the concentrationgradient of Cr and Mo near the interdendrites is the lowest compared with other cooling rates, which inhibits the growthrate of the σ phase nuclei and produces a more uniform microstructure. Corrosion test results show that pitting corrosion issensitive to the increase in the contents of Cr and Mo in the σ phase. The higher the content of Cr and Mo in the σ phase, themore serious the depletion of Cr and Mo near the interdendrites, and the worse the corrosion resistance.

Influence of Vanadium Substitution on Phase Structure, Magnetic and Dielectric Properties of BiFeO₃ Ceramics

Qiang Li,Shengxiang Bao,Tao Hong,Libo Ai,Yingli Liu,Yulan Jing,Jie Li 한국자기학회 2018 Journal of Magnetics Vol.23 No.1

BiFe1-xVxO₃ (x = 0.00, 0.03, 0.05, 0.07, 0.09) ceramics were prepared by solid-sate reaction method. The effect of V<SUP>5+</SUP> substitution on phase structure, morphology, magnetic and dielectric properties had been investigated. The Rietveld refinement of the X-Ray diffraction data from the BiFe1-xVxO₃ (BFVO) ceramics showed samples with rhombohedral structure (R3c) for x = 0.00-0.07. When x = 0.09, partial phase structural be translated to orthorhombic phase (Pnma). Morphology showed two kinds of crystal and proved the phase to be transition. Magnetic measurements exhibited weak ferromagnetic behavior of sample. BiFe0.93V0.07O₃ ceramic exhibited the highest value of saturation magnetization. Due to V<SUP>5+</SUP> substitution, maybe BFVO attributed weak ferromagnetism to structure distortion and phase transition. Dielectric constant kept a stable value in a wide range frequency of 1 MHz to 1 GHz. With V<SUP>5+</SUP> ions increasing, dielectric constant increased significantly, while dielectric loss kept a low value. These results indicated that BFVO may be promising for application in magneto-electric devices.

Effect of Cooling Rate on Pitting Corrosion Behavior of 904L Austenitic Stainless Steel in a Simulated Flue Gas Desulfurization Solution

Miaomiao Li,Dening Zou,Yunong Li,Libo Tong 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3

904L super austenitic stainless steel is prone to harmful secondary phase precipitation, which reduces corrosion resistance. The cooling rate during the solidification of steel is one of the critical factors affecting the precipitation of brittle phases instainless steel metals. In this paper, the effect of the cooling rates (6, 50, 100, 500, and 1000 °C min−1) on the initial corrosionbehavior of 904L steel in a simulated flue gas desulfurization (FGD) solution was studied by electrochemical measurementsand microscopic morphology observation. The results show that as the cooling rates increases, the primary solidification temperatureand the secondary dendrite arm spacing decrease. The precipitated phase in the steel is a σ-phase mainly distributedinterdendrites and forms zones of chromium and molybdenum depletion, reducing pitting resistance. With the increase in thecooling rate, the corrosion resistance increases first and then decreases, and reaches the maximum at 100 °C min−1. At thesame time, different cooling rates result in different contents of Cr and Mo in σ phase. At 100 °C min−1, the concentrationgradient of Cr and Mo near the interdendrites is the lowest compared with other cooling rates, which inhibits the growthrate of the σ phase nuclei and produces a more uniform microstructure. Corrosion test results show that pitting corrosion issensitive to the increase in the contents of Cr and Mo in the σ phase. The higher the content of Cr and Mo in the σ phase, themore serious the depletion of Cr and Mo near the interdendrites, and the worse the corrosion resistance.

Chemo-Mechanical Manufacturing of Fused Silica by Combining Ultrasonic Vibration with Fixed-Abrasive Pellets

Yaguo Li,Yongbo Wu,Libo Zhou,Masakazu Fujimoto,Jian Wang,Qiao Xu,Shoichi Sasaki,Masaaki Kemmochi 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

Vibration-assisted grinding, in which harder abrasives than materials to be machined are employed, has been a viable and effective approach to increasing material removal rate (MRR) and/or reducing surface roughness of ground surfaces. We transfer this ideology to fused silica polishing by incorporating ultrasonic vibration into recently developed fixed-abrasive pellets in an attempt to enhance MRR and/or to improve manufactured surface quality. A prototype ultrasonic vibrator, the heart of the polishing head, was designed and the related experimental work was performed on an in-house built setup in conjunction with the constructed head. The vibrator is devised for the generation of 2-D tool path despite using only one actuator in lieu of two actuators in conventional 2-D ultrasonic machining systems. We then combined the ultrasonic vibration with fixed abrasive polishing pellets to machine fused silica glass. Machining experiments reveal that MRR is considerably increased up to >50% upon the introduction of ultrasonic vibration (UV)whilst surface roughness is not degraded appreciably. It was also noted that a overwhelmingly greater deal of polishing debris was dispelled during ultrasonic vibration assisted polishing than conventional bound-abrasive polishing, which may account for the greater MRR in UV assisted polishing.

Removal of Uranium from Uranium Plant Wastewater Using Zero-Valent Iron in an Ultrasonic Field

Jing Li,Libo Zhang,Jinhui Peng,Jinming Hu,Lifeng Yang,Aiyuan Ma,Hongying Xia,Wenqian Guo,Xia Yu 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.3

Uranium removal from uranium plant wastewater using zero-valent iron in an ultrasonicfield was investigated. Batch experiments designed by the response surface methodology(RSM) were conducted to study the effects of pH, ultrasonic reaction time, and dosage ofzero-valent iron on uranium removal efficiency. From the experimental data obtained inthis work, it was found that the ultrasonic method employing zero-valent iron powdereffectively removes uranium from uranium plant wastewater with a uranium concentrationof 2,772.23 mg/L. The pH ranges widely from 3 to 7 in the ultrasonic field, and theprediction model obtained by the RSM has good agreement with the experimental results.

Chemo-Mechanical Manufacturing of Fused Silica by Combining Ultrasonic Vibration with Fixed-Abrasive Pellets

Yaguo Li,Yongbo Wu,Libo Zhou,Masakazu Fujimoto,Jian Wang,Qiao Xu,Shoichi Sasaki,Masaaki Kemmochi 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.5

Vibration-assisted grinding, in which harder abrasives than materials to be machined are employed, has been a viable and effective approach to increasing material removal rate (MRR) and/or reducing surface roughness of ground surfaces. We transfer this ideology to fused silica polishing by incorporating ultrasonic vibration into recently developed fixed-abrasive pellets in an attempt to enhance MRR and/or to improve manufactured surface quality. A prototype ultrasonic vibrator, the heart of the polishing head, was designed and the related experimental work was performed on an in-house built setup in conjunction with the constructed head. The vibrator is devised for the generation of 2-D tool path despite using only one actuator in lieu of two actuators in conventional 2-D ultrasonic machining systems. We then combined the ultrasonic vibration with fixed abrasive polishing pellets to machine fused silica glass. Machining experiments reveal that MRR is considerably increased up to >50% upon the introduction of ultrasonic vibration (UV) whilst surface roughness is not degraded appreciably. It was also noted that a overwhelmingly greater deal of polishing debris was dispelled during ultrasonic vibration assisted polishing than conventional bound-abrasive polishing, which may account for the greater MRR in UV assisted polishing.

Cell Division Cycle Associated 8 Is a Key Regulator of Tamoxifen Resistance in Breast Cancer

Dehai Yu,Libo Shi,Yuhui Bu,Weidong Li 한국유방암학회 2019 Journal of breast cancer Vol.22 No.2

Purpose: Breast cancer (BC) is one of the most common malignancies globally, and millions of women worldwide are diagnosed with BC every year. Up to 70% of BC patients are estrogen receptor (ER)-positive. Numerous studies have shown that tamoxifen has a significant therapeutic effect on both primary and metastatic ER-positive BC patients. Although tamoxifen is currently one of the most successful therapeutic agents for BC, a significant proportion of patients will eventually become resistant to tamoxifen, leading to tumor recurrence and metastasis. Knowledge about the development of tamoxifen resistance in BC patients is still limited. Methods: We applied a loss-and-gain method to study the biological functional role of cell division cycle associated 8 (CDCA8) in tamoxifen resistance in BC cells. Results: We found that CDCA8 was significantly elevated in tamoxifen-resistant BC cells. Knockdown of CDCA8 expression significantly inhibited the proliferation of tamoxifen-resistant BC cells and reduced their resistance to tamoxifen. In contrast, overexpression of CDCA8 promoted the growth of tamoxifen-sensitive BC cells and induced their resistance to tamoxifen. Conclusion: In this study, we reported that CDCA8 is a key regulator of tamoxifen resistance in BC, suggesting that CDCA8 may serve as a potential therapeutic target for BC treatment.

Research on Control Force Aerodynamic Model of a Guided Rocket With an Isolated-rotating Tail Rudder

Chen Wang,Libo Ding,He Zhang,Li Xiao,Shihao Zhang 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.1

Isolated rotating tail rudder technology provides a low-cost and miniaturized solution for the correction and guidance of a man-portable rocket. The results of three turbulence models (the Spalart–Allmaras model, standard k–ε model, and shear stress transport k–ω model) were compared with wind-tunnel model test data, and the best turbulence model was selected. An aerodynamic model of the rotating tail rudder was developed by identifying its turbulent region, and the influences of the Mach number, angle of attack, and tail rudder speed on the projectile aerodynamics were revealed. The aerodynamic parameters were fitted using a least-squares method, and the vector variation characteristics of the period-averaged control force were analyzed. The results from the shear stress transport k–ω model were closest to the results of the wind-tunnel tests. The aerodynamic model was able to fit the simulation results well. The average control force of the tail rudder over a rotation cycle is not zero, and it increases with increasing angle of attack, Mach number, and tail rudder rotation speed. This study provides a basis for aerodynamic research examining the same type of projectile, and it has guiding significance for the control design of isolated rotating tail rockets.

Analysis of Risk Factors for a Poor Prognosis in Patients with Anti-N-Methyl-D-Aspartate Receptor Encephalitis and Construction of a Prognostic Composite Score

Yejia Mo,Li Wang,Libo Zhu,Feng Li,Gang Yu,Yetao Luo,Meng Ni 대한신경과학회 2020 Journal of Clinical Neurology Vol.16 No.3

Background and Purpose Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most-common form of autoimmune encephalitis, but its early diagnosis is challenging. This study aimed to identify the risk factors for a poor prognosis in anti-NMDAR encephalitis and construct a prognostic composite score for obtaining earlier predictions of a poor prognosis. Methods We retrospectively analyzed the clinical data, laboratory indexes, imaging findings, and electroencephalogram (EEG) data of 60 patients with anti-NMDAR encephalitis. The modified Rankin Scale (mRS) scores of patients were collected when they were discharged from the hospital. The mRS scores were used to divide the patients into two groups, with mRS scores of 3–6 defined as a poor prognosis. Logistic regression analysis was used to analyze independent risk factors related to a poor prognosis. Results This study found that 23 (38.3%) and 37 (61.7%) patients had good and poor prognoses, respectively. Logistic regression analysis showed that age, disturbance of consciousness at admission, and ≥50% slow waves on the EEG were significantly associated with patient outcomes. An age, consciousness, and slow waves (ACS) composite score was constructed to predict the prognosis of patients with anti-NMDAR encephalitis at an early stage based on regression coefficients. Conclusions Age, disturbance of consciousness at admission, and ≥50% slow waves on the EEG were independent risk factors for a poor prognosis. The ACS prognostic composite score could play a role in facilitating early predictions of the prognosis of anti-NMDAR encephalitis.

Research on Safety Monitoring and Warning System Based on Information Fusion for Coking Production

Nailu Zhang,Libo Li,Xin Liu,Yuzhe Zhang,Fuchao Li 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.8

Coking production process is very complex, and full of risk factors, toxic and harmful substance, it’s a typical high risk industry. In view of the prominent safety hazards and strong interference to safety monitoring in coking production, put forward a kind of safety monitoring and warning system based on information fusion for coking production. To achieve the target that safety condition was monitored accurately and hazardous situation warned reliably, safety information of the monitoring and warning areas was collected by sensor network which include combustible gas sensor, dust sensor, temperature sensor, pressure sensor, flowmeter and IP camera ,and the information fusion model of safety monitoring and warning was established, and then, through the BP neural network and the D-S evidence theory algorithm, various safety information was fused. Actual tests show that it has achieved the goal that monitoring accurately and warning reliably. It is of great significance to ensure the security of coking production.