Enhanced Microwave Absorption Properties of Metal Organic Framework (MOF)-Derived Carbonaceous ZnO Incorporated Reduced Graphene Oxide Composites

Zhongfei Liu,Jiangtao Yuan,HUI ZHANG,Kuangwei Xiong,Shaowei Jin,Peihong Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

In this paper, the MOFs-derived carbonaceous ZnO and RGO (carbonaceous ZnO/RGO) composites have been prepared by the wet chemical method and carbonization process. The as-prepared products are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), Raman spectra, thermogravimetric (TG) analysis and X-ray photoelectron spectroscopy (XPS). The electromagnetic parameters of carbonaceous ZnO/RGO composites are investigated by the vector network analyzer. The results exhibit carbonaceous ZnO/RGO composites have a maximum absorption of - 37.12 dB at 6 GHz with thickness of 3.5 mm and the effective absorption (below -10 dB) bandwidth is up to 1.92 GHz (from 5.28 to 7.2 GHz). Thus, the carbonaceous ZnO/RGO composites have great potential in the field of electromagnetic wave absorption.

Study on suppression strategy of jet lag effect in melt electrowriting

Zhongfei Zou,Yu Wang,Zhen Shen,Nan Luo 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

The melt electrowriting (MEW) has broad applications in regenerative medicine and micro-nano electronics. It is an efficient micro-nano scale additive manufacturing technology; however, the fiber jet lag effect of MEW limits the deposition precision and resolution of fiber shape. In this study, the principle of the jet lag effect is studied to overcome the defect of printed structure distortion and improve the ability to print complex structures. A mathematical model of trailing fiber trajectory is established. The study covers jet lag and liquid rope coiling analysis at different speeds. A strategy is adopted by introducing a buffer zone at the corner of the printing structure. The printing path is subdivided and optimized to suppress the influence of jet lag. The results show that the deposited fibers' corner radius is around 63.81±5.66 μm, which is significantly smaller than that of unoptimized groups. Finally, by utilizing the improved printing paths, the high-precision and complex structures are printed, which demonstrates the feasibility of optimizing the buffer zone for the MEW.

Contrast-Enhanced Spectral Mammography Versus Ultrasonography: Diagnostic Performance in Symptomatic Patients with Dense Breasts

Zhongfei Lu,Cuijuan Hao,Yan Pan,Ning Mao,Xin Wang,Xundi Yin 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.4

Objective: To compare the diagnostic performance of contrast-enhanced spectral mammography (CESM) versus ultrasonography (US) in symptomatic patients with dense breasts, while using histology as the gold standard. Materials and Methods: After obtaining approval from the local ethics board, this prospective study collected data from patients with symptomatic breasts who underwent CESM and US examinations from May 1, 2017 to September 30, 2017. We then selected those with dense breasts and pathological results as our sample population. Both CESM and US results were classified by a radiologist through the Breast Imaging Reporting and Data System, and the results were compared with their corresponding histological results. The chi-square test was conducted to compare the diagnostic performance of CESM and US, and the receiver operating characteristic curves for the two imaging modalities were obtained. Results: A total of 131 lesions from 115 patients with dense breasts were included in this study. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 93.8%, 88.1%, 88.2%, 93.7%, and 90.8% for CESM, and 90.6%, 82.1%, 82.9%, 90.2%, and 86.3% for US, respectively. The p values for sensitivity, specificity, PPV, NPV, and accuracy were 0.687, 0.388, 0.370, 0.702, and 0.238, respectively. The area under the curve of CESM (0.917) was comparable with that of US (0.884); however, the differences between CESM and US were not statistically significant (p = 0.225). Eight false-positive cases and 4 false-negative cases for breast cancer were found in CESM, while 12 false-positive cases and 6 false-negative cases were found in US. Conclusion: The diagnostic performances of CESM and US are comparable in symptomatic women with dense breasts; however, the routine use of additional US imaging is questionable for lesions that can be detected by CESM.

Design of mechanical coxa joints based on three-degree-of-freedom spherical parallel manipulators

Yanbiao Li,Zhenlin Jin,Zhongfei Wang,Ming-sheng Jin,Yi Liu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.1

We addressed the issue of the design of mechanical coxa joints based on three-degree-of-freedom spherical parallel manipulators using the parameter statistics optimum method based on index atlases. The coxa joints have the advantages of high payload, high accuracy, and good technological efficiency. The first step of the design and prototyping used in this paper develops the direct and inverse displacement equations from the layout feature of the mechanical coxa joints. Then, the shapes of a constant-orientation workspace of the mechanical coxa joints are described, and the effects of the design parameters on the workspace volume are studied quantitatively. The next step deals with the graphical representation of the atlases that illustrates the relationship between performance evaluation index and design parameters based on the kinematics and torque analysis of the mechanical coxa joints. Finally, the geometric parameters of the coxa joints are obtained by the parameter statistics optimum method based on the index atlases. Considering assembly conditions, the design scheme of the mechanical coxa joints is developed, which provides a theoretical basis for the application of the mechanical coxa joints.

Neutrophil extracellular traps mediate the crosstalk between plaque microenvironment and unstable carotid plaque formation

Cao Yu,Chen Minghui,Jiao Xinyu,Li Shuijie,Wang Dong,Zhan Yongxuan,Li Jiaju,Hao Zhongfei,Li Qingbin,Liu Yang,Feng Yan,Li Ruiyan,Wang Hongjun,Liu Mingli,Fu Qiang,Li Yongli 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-

The development of unstable carotid atherosclerotic plaques is associated with the induction of neutrophil extracellular traps (NETs) via the activation of diverse inflammatory mediators in the circulating bloodstream. However, the underlying mechanisms through which NETs influence the microenvironment of atherosclerotic plaques and contribute to the development of unstable carotid plaques remain largely elusive. The objective of this study was to elucidate the role of myeloid differentiation protein 1 (MD-1, LY86)-induced NETs underlying the crosstalk between unstable plaque formation and the plaque microenvironment. We employed bioinformatics analysis to identify key genes associated with carotid-unstable plaque, followed by comprehensive validation using various experimental approaches on tissue specimens and plasma samples classified based on pathological characteristics. Patients with carotid-unstable plaques exhibited elevated plasma concentrations of MD-1 (LY86), while patients with stable plaques demonstrated comparatively lower levels. Furthermore, soluble MD-1 was found to induce the formation of NETs through activation of Toll-like receptor signaling pathway. The proliferative and immature vascularization effects of NETs on endothelial cells, as well as their inhibitory impact on cell migration, are directly correlated with the concentration of NETs. Additionally, NETs were found to activate the NF-κB signaling pathway, thereby upregulating ICAM1, VCAM1, MMP14, VEGFA, and IL6 expression in both Human umbilical vein endothelial cells (HUVECs) and HAECs. Subsequently, a significant increase in intraplaque neovascularization by NETs results in poor carotid plaque stability, and NETs in turn stimulate macrophages to produce more MD-1, generating a harmful positive feedback loop. Our findings suggest that soluble MD-1 in the bloodstream triggers the production of NETs through activation of the Toll-like receptor signaling pathway and further indicate NETs mediate a crosstalk between the microenvironment of the carotid plaque and the neovascularization of the intraplaque region. Inhibiting NETs formation or MD-1 secretion may represent a promising strategy to effectively suppress the development of unstable carotid plaques.