Two-dimensional metal organic framework for effective gas absorption

Cheng, Kaiwu,Li, Yaojia,Gao, Zhiguo,Chen, Fanghui,You, Chaoqun,Sun, Baiwang Elsevier 2019 Inorganic Chemistry Communications Vol.101 No.-

<P><B>Abstract</B></P> <P>Herein, crystalline metal organic framework (MOF) nanosheets have been fabricated through using a modified soft physical exfoliation method from bulk crystals of a layered MOF, [Cd(4,4′‑bpy)<SUB>2</SUB>(H<SUB>2</SUB>O)<SUB>2</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB>·(2,4′‑bpy)<SUB>2</SUB>·H<SUB>2</SUB>O (MOF-1), and fully characterized via transmission electron microscope (TEM), scanning electron microscopy (SEM), and atomic force microscope (AFM). The delaminated MOF-1 nanosheets with porous structure showed good growth potential in selective gas adsorption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Using a modified soft physical exfoliation method from bulk crystals, we firstly synthesized a layered MOF nanosheets. </LI> <LI> The MOF-2 nanosheets revealed a superior absorption performance. </LI> <LI> The delaminated MOF nanosheets with porous structure showed good growth potential in selective gas adsorption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Residual stress measurement on propellant tank of 2219 aluminum alloy and study on its weak spot

Chaoqun Huang,Huan Li,Jianxiong Li,Chuanguang Luo,Yanbing Ni 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

This paper presented residual stress measurement on two circumferential Variable polarity plasma arc welding (VPPAW) joints and one circular closed Friction stir welding (FSW) joint on the propellant tank of 2219 aluminum alloy using the indentation strain-gauge method. Quite large tensile residual stresses were attached to the center and inner areas of the circular closed FSW joint. There were very large tensile stresses in some points of the two circumferential VPPAW joints, among these points, the maximum value was +253 MPa, which was about 63 % of the yield strength of 410 MPa measured in the base material. In addition, the peak of compressive residual stress was about -160 MPa. Above all, there were two typical peaks of residual stress in the circumferential VPPAW joints, one was located in the middle part while the other one was near the start/end position of the joints. Combining the result of residual stress measurement with the characteristics of the tank structure, it can be concluded that circular closed FSW joint around the flange was a weak spot on the propellant tank. And the most vulnerable point on the circular closed FSW joint has also been found.

Contact Tracking Development Trend Using Bibliometric Analysis

Chaoqun Li,Zhigang Chen,Tongrui Yu,Xinxia Song 한국정보처리학회 2022 Journal of information processing systems Vol.18 No.3

The new crown pneumonia (COVID-19) has become a global epidemic. The disease has spread to mostcountries and poses a challenge to the healthcare system. Contact tracing technology is an effective way forpublic health to deal with diseases. Many experts have studied traditional contact tracing and developed digitalcontact tracking. In order to better understand the field of contact tracking, it is necessary to analyze thedevelopment of contact tracking in the field of computer science by bibliometrics. The purpose of this researchis to use literature statistics and topic analysis to characterize the research literature of contact tracking in thefield of computer science, to gain an in-depth understanding of the literature development status of contacttracking and the trend of hot topics over the past decade. In order to achieve the aforementioned goals, weconducted a bibliometric study in this paper. The study uses data collected from the Scopus database. Whichcontains more than 10,000 articles, including more than 2,000 in the field of computer science. For populartrends, we use VOSviewer for visual analysis. The number of contact tracking documents published annuallyin the computer field is increasing. At present, there are 200 to 300 papers published in the field of computerscience each year, and the number of uncited papers is relatively small. Through the visual analysis of the paper,we found that the hot topic of contact tracking has changed from the past “mathematical model,” “biologicalmodel,” and “algorithm” to the current “digital contact tracking,” “privacy,” and “mobile application” and othertopics. Contact tracking is currently a hot research topic. By selecting the most cited papers, we can displayhigh-quality literature in contact tracking and characterize the development trend of the entire field throughtopic analysis. This is useful for students and researchers new to field of contact tracking ai well as forpresenting our results to other subjects. Especially when comprehensive research cannot be conducted due totime constraints or lack of precise research questions, our research analysis can provide value for it.

Activation of Tyrosine Metabolism in CD13+ Cancer Stem Cells Drives Relapse in Hepatocellular Carcinoma

Li Sun,Lin Zhang,Jun Chen,Chaoqun Li,Hongqin Sun,Jiangrong Wang,Hong Xiao 대한암학회 2020 Cancer Research and Treatment Vol.52 No.2

Purpose Cancer stem cells (CSCs) are naturally resistant to chemotherapy, explaining why tumor relapse frequently occurs after initial regression upon administration of chemotherapeutic agents in most cases. A CSC population characterized by CD13 expression has been identified in hepatocellular carcinoma (HCC). In the current study, we aimed to clarify the molecular mechanism by which it escapes conventional therapies. Materials and Methods Here, we used flow cytometry to examine the percentage of CD13+ CSCs in HepG2 and HuH7 cells after chemotherapy. Using in vitro isotope labeling technique, we compared metabolic pathways between CD13+ and CD13– subpopulations. Using co-immunoprecipitation and western blotting, we determined the target expressions in protein levels under different conditions. We also performed immunohistochemistry to detect the target proteins under different conditions. Animal models were constructed to verify the potential role of tyrosine metabolism in post-chemotherapeutic relapse in vivo. Results We observed that quiescent CD13+ CSCs are enriched after chemotherapy in HCCs, and serve as a reservoir for recurrence. Mechanistically, CD13+ CSCs were dependent on aerobic metabolism of tyrosine rather than glucose as energy source. Tyrosine metabolism also generated nuclear acetyl-CoA to acetylate and stabilize Foxd3, thereby allowing CD13+ CSCs cells to sustain quiescence and resistance to chemotherapeutic agents. Conclusion These findings encourage further exploration of eliminating CD13+ cells by targeting specific metabolic pathways to prevent recurrence in HCCs.

Identification of Plasmid-Free Chlamydia muridarum Organisms Using a Pgp3 Detection-Based Immunofluorescence Assay

Chaoqun Chen,Guangming Zhong,Lin Ren,Chunxue Lu,Zhongyu Li,Yimou Wu 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.10

Comparisons of Safety Factors for Slope in Nonlinear Soils

Chaoqun Hou,Rongjian Zhang,Yongxin Li,Zhibin Sun,Biao Zhang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.10

Slope stability assessment is one of the most important issues for geotechnical engineers. In the framework of a nonlinear failure criterion, four different types of safety factors are presented and their relationships are investigated for soil slope in this study. The variational method is incorporated into the kinematic approach of limit analysis to assess the stability of soil slope with known geometric boundary, and seismic effects are considered. The seismic loads are simplified as external forces acting on the slope. A rotational failure mechanism is used to describe the sliding mode of slopes. The differential equations for the sliding surface and corresponding stress distribution are derived using the variational method and then are employed to generate the sliding surface via the fourth-order Runge-Kutta approach. To avoid the computational complexity, the energy-work balance equation of the kinematic approach, instead of the static equilibrium equation, is used to judge whether the state of the slope is critical. The safety factor is designed as the minimum factor that brings the slope in the limit state. Computational schemes are proposed to calculate the values of safety factors. The validity of the proposed approach is demonstrated through comparison with previous works. Finally, parametric study is conducted to further reveal the relationships among the four types of safety factors.

Galloping of steepled main cables in long-span suspension bridges during construction

Yonghui An,Chaoqun Wang,Shengli Li,Dongwei Wang 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.23 No.6

Large amplitude oscillation of steepled main cables usually presents during construction of a long-span bridge. To study this phenomenon, six typical main cables with different cross sections during construction are investigated. Two main foci have been conducted. Firstly, aerodynamic coefficients of a main cable are obtained and compared through simulation and wind tunnel test: (1) to ensure the simulation accuracy, influences of the numerical model's grid size, and the jaggy edges of main cable's aerodynamic coefficients are investigated; (2) aerodynamic coefficients of main cables at different wind attack angles are obtained based on the wind tunnel test in which the experimental model is made by rigid plastic using the 3D Printing Technology; (3) then numerical results are compared with wind tunnel test results, and they are in good agreement. Secondly, aerodynamic coefficients of the six main cables at different wind attack angles are obtained through numerical simulation. Then Den Hartog criterion is used to analyze the transverse galloping of main cables during construction. Results show all the six main cables may undergo galloping, which may be an important reason for the large amplitude oscillation of steepled main cables during construction. The flow structures around the main cables indicate that the characteristic of the airflow trajectory over a steepled main cable may play an important role in the galloping generation. Engineers should take some effective measures to control this harmful phenomenon due to the big possibility of the onset of galloping during the construction period.

Contribution of Lipids in Honeybee (Apis mellifera) Royal Jelly to Health

Xing-An Li,Chaoqun Huang,Yun-Bo Xue 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.2

Honeybee (Apis mellifera) royal jelly (RJ) has a long history in human medicine because of its health-protecting properties. To develop a fundamental and comprehensive understanding of lipids in RJ, this article reviews the available literature on lipid compounds identified from RJ extracts and in vitro pharmacological effects of 10-hydroxy-2-decenoic acid in RJ and other closely related compounds, some of which are also identified as lipid compounds in RJ. Overall, the lipids in RJ are composed of mostly (aliphatic) fatty acids, almost all of which are present as free fatty acids and scarcely any as esters. Most fatty acids in RJ are medium-chain fatty acids, whether hydroxylated in terminal and/or internal positions, terminated with mono- or dicarboxylic acid groups, and saturated or monounsaturated at the 2-position. Besides these fatty acids, lipids in RJ contain sterols in minor amounts. Lipids in RJ are useful as preventive and supportive medicines with functionalities that include potential inhibitors of cancer growth, immune system modulators, alternative therapies for menopause, skin-aging protectors, neurogenesis inducers, and more. Taken together, the evidence suggests that health-protecting properties of RJ can be, in part, ascribed to actions of lipids in RJ.

Galloping of steepled main cables in long-span suspension bridges during construction

An, Yonghui,Wang, Chaoqun,Li, Shengli,Wang, Dongwei Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.23 No.6

Large amplitude oscillation of steepled main cables usually presents during construction of a long-span bridge. To study this phenomenon, six typical main cables with different cross sections during construction are investigated. Two main foci have been conducted. Firstly, aerodynamic coefficients of a main cable are obtained and compared through simulation and wind tunnel test: (1) to ensure the simulation accuracy, influences of the numerical model's grid size, and the jaggy edges of main cable's cross section on main cable's aerodynamic coefficients are investigated; (2) aerodynamic coefficients of main cables at different wind attack angles are obtained based on the wind tunnel test in which the experimental model is made by rigid plastic using the 3D Printing Technology; (3) then numerical results are compared with wind tunnel test results, and they are in good agreement. Secondly, aerodynamic coefficients of the six main cables at different wind attack angles are obtained through numerical simulation. Then Den Hartog criterion is used to analyze the transverse galloping of main cables during construction. Results show all the six main cables may undergo galloping, which may be an important reason for the large amplitude oscillation of steepled main cables during construction. The flow structures around the main cables indicate that the characteristic of the airflow trajectory over a steepled main cable may play an important role in the galloping generation. Engineers should take some effective measures to control this harmful phenomenon due to the big possibility of the onset of galloping during the construction period.

Research on 3D Laser Scanning Monitoring Method for Mining Subsidence Based on the Auxiliary for Probability Integral Method

Lei Wang,Shangjun Zhu,Chuang Jiang,Jingyu Li,Kegui Jiang,Chaoqun Teng,Tao Wei,Qing-biao Guo 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

When 3D laser scanning technology is used to monitor the surface deformation of mining subsidence in mining area, the surface of the working face is covered with a large number of vegetation, and the surface water accumulates above the working face, which makes the point cloud data obtained by the 3D laser scanning difficult to denoise, or even missing. At this time, the conventional 3D laser scanning technology can not obtain the surface deformation field of mining subsidence. Aiming at the above problems, the 3D laser scanning monitoring method for mining subsidence based on the auxiliary for PIM proposed (3DLS-PIM). Firstly, this paper introduces the PIM prediction model. Secondly, the mining subsidence observation equation based on 3DLS-PIM is constructed, and then the prediction parameters of PIM are solved based on quantum particle swarm optimization (QPSO). Finally, according to the PIM and its parameters, the mining subsidence surface deformation basin is predicted and obtain the surface deformation field of mining subsidence. Robust experiments show that QPSO has a certain ability to resist random errors and gross errors. The results of engineering application show that the mining area 3D deformation monitoring method proposed in this paper has certain engineering application value.