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Surface Modification on Biodegradable Magnesium Alloys as Orthopedic Implant Materials to Improve the Bio-adaptability:A Review

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Journal of Materials Science & Technology 2016年第9期32卷 827-834页

作者： Peng Wan Lili Tan ke yang Institute of Metal Research Chinese Academy of Sciences

Magnesium （Mg） and its alloys as a novel kind of biodegradable material have attracted much funda- mental research and valuable exploration to develop its clinical application, Mg alloys degrade too fast at the early stage after implantation, thus commonly leading to some problems such as osteolysis, early fast mechanical loss, hydric bubble aggregation, gap formation between the implants and the tissue. Surface modification is one of the effective methods to control the degradation property of Mg alloys to adapt to the need of organism. Some coatings with bioactive elements have been developed, especially for the micro-arc oxidation coating, which has high adhesion strength and can be added with Ca, P, and Sr elements. Chemical deposition coating including bio-mimetic deposition coating, electro-deposition coating and chemical conversion coating can provide good anticorrosion property as well as better bioactivity with higher Ca and P content in the coating. From the biodegradation study, it can be seen that surface coating protected the Mg alloys at the early stage providing the Mg alloy substrate with lower degra-dation rate. The biocompatibility study showed that the surface modification could provide the cell and tissue stable and weak alkaline surface micro-environment adapting to the cell adhesion and tissue growth. The surface modification also decreased the mechanical loss at the early stage adapting to the load- bearing requirement at this stage. From the interface strength between Mg alloys implants and the surrounding tissue study, it can be seen that the surface modification improved the bio-adhesion of Mg alloys with the surrounding tissue, which is believed to be contributed to the tissue adaptability of the surface modification. Therefore, the surface modification adapts the biodegradable magnesium alloys to the need of hiodegradation, biocompatibility and mechanical loss property. For the different clinical application, different surface modificatio

关键词： Bio-adaptability Coating Biodegradable Magnesium alloys Orthopedic implants

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Phase transition in bilayer quantum Hall system with opposite magnetic field

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Chinese Physics B 2023年第9期32卷 87-96页

作者：杨珂 Kavli Institute for Theoretical Sciences University of Chinese Academy of SciencesBeijing 100190China

We construct a mapped bilayer quantum Hall system to realize the proposal that two nearly flatbands have opposite Chern *** the C=±1 case,the two Landau levels of the bilayer experience opposite magnetic *** consider a mapped bilayer quantum Hall system at total fillingν_(t)=1/2+1/2where the intralayer interaction is repulsive and the interlayer interaction is *** take exact diagonalization(ED)calculations on a torus to study the phase transition when the separation distance d/l_(B)is *** critical point at d_(c)/l_(B)=0.68 is characterized by a collapse of degeneracy and a crossing of energy *** the region d/l_(B)d_(c)/l_(B),a crossover from the d→d_(c)limit to the large d limit is *** electron and hole composite Fermion liquids(CFL)are realized by composite Fermions(CF)which attach opposite fluxes,respectively.

关键词： fractional quantum Hall effect bilayer quantum Hall system opposite magnetic field quantum phase transition

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Wing tip vortex structure behind an airfoil with flaps at the tip

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Science China(Physics,Mechanics & Astronomy) 2011年第4期54卷 743-747页

作者： yang ke XU ShengJin School of Aerospace Tsinghua University Beijing 100084 China

In this work, the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry （PIV） system. The experiment was carried out in a low speed wind tunnel with a test section of 0.5 m x 0.5 m. The Reynolds number （Re）, defined by the chord length of the wing （C）, was 8.1 x 104. The angle of attack was fixed at 10~. The PIV measurements were made from 0 to 2C, measured from the trailing edge of the model. The dihedral angle of three flaps was -15~, 0~ and 15~, respectively. Compared with the clean airfoil, the one with three flaps significantly changed the wing tip vortex structure, the vorticity and the core of the wing tip vortex. The occurrence of three flaps decreased the gradient of pressure on the two sides of the wing tip, which depressed wing tip vortex formation to some extent. Vortices shed from three flaps influence the evolution of the wingtip vortex generated by the base airfoil. The interaction of those vortices resulted in a weakening of the wing tip vortex.

关键词： wing tip vortex flap PIV

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Precision screening for esophageal squamous cell carcinoma in China

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Chinese Journal of Cancer Research 2020年第6期32卷 673-682页

作者： Zhonghu He yang ke key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing) Laboratory of GeneticsPeking University Cancer Hospital&InstituteBeijing 100142China

Esophageal squamous cell carcinoma(ESCC)is the predominant subtype of esophageal cancer in China,and this neoplasm is associated with high morbidity and mortality as well as clear geographical *** primary prevention for ESCC lacks a clear intervention target,secondary prevention,also known as screening and early diagnosis and early treatment,has become the mainstay of ESCC prevention and control in *** screening in China has been subject to decades of evaluation and ***,the ESCC screening strategy currently adopted in China has encountered a developmental *** this review,we have summarized studies and significant findings for ESCC screening and proposed advancement of screening strategies as follows:1)evidence from randomized controlled trials is needed to support the effectiveness and health economic value of endoscopic screening for ESCC;2)the current traditional screening and surveillance strategies warrant reform,and a risk-prediction-based precision strategy should be established;and 3)a deeper understanding of the value of opportunistic screening in the prevention and control of ESCC in China is called *** to the low absolute prevalence of precancerous lesions,substantial investment of resources and nonnegligible risks of invasive screening techniques,precision and individualization should be the main direction of cancer screening programs for the *** advocate cooperation on the part of Chinese scientists to solve this major China-specific health problem in the next decades.

关键词： Esophageal cancer organized screening opportunistic screening cost-effectiveness risk stratification

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Challenge and future of cancer screening in China: Insights from esophageal cancer screening practice

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Chinese Journal of Cancer Research 2023年第6期35卷 584-594页

作者： Zhonghu He yang ke State key Laboratory of Molecular Oncology Beijing Key Laboratory of Carcinogenesis and Translational ResearchDepartment of GeneticsPeking University Cancer Hospital&InstituteBeijing 100142China

Cancer stands as a prominent public health concern in China, with elusive intervention targets due to unidentified high-risk causal factors for most cancers. Consequently, emphasis has shifted towards screening, diagnosing, and treating early cancer cases within the general population. However, China faces considerable obstacles in its cancer prevention and control efforts, attributing to the complexity and heterogeneity of the occurrence, progression, and prognosis of malignant tumors across populations, time, and regions. Taking esophageal cancer screening practices as an example, this review outlines the importance and assessment of cancer screening, delineating major challenges in China's cancer prevention and control: 1) limited comprehension of cancer's natural history;2) lack of “China Evidence” supporting screening effectiveness and value;3) compromised efficiency and accuracy in current screening modality;and 4) insufficient sustainability of the current screening practices and translation of relevant scientific research achievements. To address these challenges, we propose potential coping strategies: 1)establishing tailored technologies and pathways for cancer prevention and control based on population-based and clinical epidemiological studies using high-quality designs;2) breaking conventional constraints to establish a novel cancer screening strategy aligned with real-world needs;and 3) establishing enhanced communication platforms among scientific research teams, policymakers, and industrial institutions to foster collaboration and innovation.

关键词： Cancer screening China challenge coping strategy esophageal cancer

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Equilibrium dynamics of the sub-ohmic spin-boson model at finite temperature

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Chinese Physics B 2021年第4期30卷 159-165页

作者： ke yang Ning-Hua Tong Department of Physics Renmin University of ChinaBeijing 100072China

We use the full-density matrix numerical renormalization group method to calculate the equilibrium dynamical correlation function C(ω) of the spin operator σ_(z) at finite temperature for the sub-ohmic spin-boson model.A peak is observed at the frequency ω_(T)~T in the curve of C(ω).The curve merges with the zero-temperature C(ω) in ω>>ω_(T) and deviates significantly from the zero-temperature curve in ω<<ω_(T).

关键词： spin-boson model full-density matrix renormalization group quantum phase transition dynamical correlation function finite temperature

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Multi-objective Optimization of the Distributed Permutation Flow Shop Scheduling Problem with Transportation and Eligibility Constraints

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Journal of the Operations Research Society of China 2018年第3期6卷 391-416页

作者： Shuang Cai ke yang ke Liu Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China key Laboratory of Management Decision and Information SystemsChinese Academy of SciencesBeijing 100190China National Center for Mathematics and Interdisciplinary Sciences Chinese Academy of SciencesBeijing 100190China

In this paper,we consider the distributed permutation flow shop scheduling problem(DPFSSP)with transportation and eligibility *** objectives are taken into account,i.e.,makespan,maximum lateness and total costs(transportation costs and setup costs).To the best of our knowledge,there is no published work on multi-objective optimization of the DPFSSP with transportation and eligibility ***,we present the mathematics model and constructive heuristics for single objective;then,we propose an improved The Nondominated Sorting Genetic Algorithm II(NSGA-II)for the multi-objective DPFSSP to find Pareto optimal solutions,in which a novel solution representation,a new population re-/initialization,effective crossover and mutation operators,as well as local search methods are *** on extensive computational and statistical experiments,the proposed algorithm performs better than the well-known NSGA-II and the Strength Pareto Evolutionary Algorithm 2(SPEA2).

关键词： Multi-objective optimization Distributed scheduling Permutation flow shop scheduling Transportation NSGA-II

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Hot Deformation Behavior and Processing Map of a Cu-Bearing 2205 Duplex Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2019年第12期32卷 1537-1548页

作者： Tong Xi Lu Yin Chun-Guang yang ke yang Institute of Metal Research Chinese Academy of Sciences

The hot deformation behavior and processing map of Cu-bearing 2205 duplex stainless steel(2205-Cu DSS)were investigated at temperatures of 950-1150℃ and strain rates of 0.01-10 s^-*** effects of Cu addition and different deformation parameters on deformation behavior were,respectively,characterized by analyzing flow curves,constitutive equations and *** results indicated that the shapes of flow curves strongly depended on the volume fraction of two *** deformed at low strain rate,DRV in ferrite was prompted with increase in the temperature and was further developed to continuous *** high strain rate,flow localization preferentially occurred in ferrite at low deformation temperature due to the strain partitioning and relatively less fraction of *** activation energy for 2205-Cu DSS was 452 kJ/mol and was found to connect with the variation of strain,strain rate and deformation *** optimum hot deformation parameters for 2205-Cu DSS were obtained in the temperature range of 1100-1150℃ and strain rate range of 0.1-1 s^-1 with a peak power dissipation efficiency of 41%.Flow localization was the main way to lead to flow ***,the Cu-rich precipitates were generated within a few ferrite grains when deformed at temperature lower than 1000℃.The interaction between dislocations and Cu-rich precipitates at high strain rate,as well as the limited DRV in ferrite and DRX in austenite,contributed to the complex microstructure and flow behavior.

关键词： Cu-bearing duplex stainless steel Hot deformation Processing map Dynamic recrystallization Dynamic recovery

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Enhancing General Corrosion Resistance of Biomedical High Nitrogen Nickel-Free Stainless Steel by Nitric Acid Passivation

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Acta Metallurgica Sinica(English Letters) 2020年第2期33卷 307-312页

作者： Yixun yang Qingchuan Wang Jun Li Lili Tan ke yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

A systematic study of nitric acid passivation was investigated to enhance the general corrosion resistance of biomedical high-nitrogen nickel-free stainless steels(HNSs).After passivation,the corrosion rate of HNS could dramatically reduce to 1/20 of the untreated in 37℃0.9 wt% NaCl ***,the passive film on HNS was analyzed by X-ray photoelectron *** was found that chromium enrichment in the passive film and nitrogen enrichment in the film/metal interface contributed to the improvement in general corrosion resistance of HNS.

关键词： Stainless steel Nitric acid passivation General corrosion Passive film

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Preliminary Study on Porous High-Manganese 316L Stainless Steel Through Physical Vacuum Dealloying

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Acta Metallurgica Sinica(English Letters) 2017年第8期30卷 731-734页

作者： Yibin Ren Jun Li ke yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

In this study, porous stainless steel was prepared successfully by physical vacuum dealloying method. The based alloy is high-manganese 316L-50Mn alloy. The porous high-manganese 316L stainless steel showed a three-dimensional continuous porous structure with 1-2 ktm pore size. Temperature was the key factor for the physical dealloying process to produce porous stainless steel, and the optimized treatment temperature was between 800 and 850 ~C for the high- manganese 316L-50Mn alloy.

关键词： Porous metals Dealloying Sublimation Stainless steel Manganese

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