Microwave Dielectric Properties of High-Q Mg(SnxTi1-x)O3 Ceramics

Zhijie Gong,Zhefei Wang,Lixi Wang,Zhenxiao Fu,Wei Han,Qitu Zhang,김응수 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.3

A series of Sn-doped Mg(SnxTi1-x)O3 ceramics were prepared using the conventional solid-state route. The influence of Sn4+ substitution for Ti4+ on the microstructure and microwave dielectric properties of Mg(SnxTi1-x)O3ceramics was systematically investigated. Substitution with a suitable amount of Sn can eliminate the MgTi2O5phase. The dielectric constants and temperature coefficients of resonant frequency changed slightly with the variation in Sn content in the specimens. However, the quality factors (Q) dramatically improved and were sensitive to the concentration of Sn4+. The high Q value was attributed to the uniform grain, clean and narrow grain boundary, and elimination of the MgTi2O5 phase. Moreover, the composition-optimized Mg(Sn0.05Ti0.95)O3ceramics sintered at 1390°C exhibited excellent microwave dielectric properties of εr = 17.61, Q×f = 328,543GHz, and τf = −42 ppm/°C.

Discrete Element Study on Mesoscopic Shear Mechanical Behavior of Fully Weathered Coastal Red Sandstone Considering Different Rock Mass Stability Grades

Zhijie Wang,Xiaohao Rui,Haiyan Xu,Mingfan Zhao,Zhihong Qiu,Zengzhao Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11

The macro parameters such as cohesion and internal friction angle are usually measured on experimental test. The macro shear mechanical behaviors are determined by mesoscopic shear mechanical behaviors, which are difficult to be measured accurately on experimental test. This paper aims to study the mesoscopic shear mechanical behaviors of fully weathered coastal red sandstone (FWCRS) such as the force and displacement of rock particles, the force chain network, the microcracks and the coordination number, which can be systematically studied by discrete element software such as Particle Flow Code (PFC). This paper established models characterizing FWCRS with different rock mass stability grades by results obtained on experimental tests, and investigated the differences of their mesoscopic shear mechanical behaviors. The results show that the mesoscopic shear mechanical behaviors of FWCRS can be characterized by performing direct shear simulation and the differences among different rock mass stability grades were also revealed. As the stability increases from grade 1 to grade 5, the shear stiffness increases, the number of microcracks reduces by 48.07%, and there are significant differences in properties of shear band, development of microcrack, the coordination number and the force chain network. The research results can provide reference for the related research such as the evolution of mesoscopic shear mechanical behaviors in the failure process of rock mass in FWCRS and similar strata.

A new suggestion for determining 2D porosities in DEM studies

Wang, Zhijie,Ruiken, Axel,Jacobs, Felix,Ziegler, Martin Techno-Press 2014 Geomechanics & engineering Vol.7 No.6

In discrete element modeling, 2D software has been widely used in order to gain further insights into the fundamental mechanisms with less computational time. The porosities used in 2D DEM studies should be determined with appropriate approaches based on 3D laboratory porosities. This paper summarizes the main approaches for converting porosities from 3D to 2D for DEM studies and theoretical evaluations show that none of the current approaches can be widely used in dealing with soil mechanical problems. Therefore, a parabolic equation and a criterion have been suggested for the determination of 2D porosities in this paper. Moreover, a case study has been used to validate that the 2D porosity obtained from the above suggestion to be rational with both the realistic contact force distribution in the specimen and the good agreement of the DEM simulation results of direct shear tests with the corresponding experimental data. Therefore, the parabolic equation and the criterion are suggested for the determination of 2D porosities in a wide range of polydisperse particle systems, especially in dealing with soil mechanical problems.

The synthesis of MDMO-PPV capped PbS nanorods and their application in solar cells

Zhijie Wang,Shengchun Qu,Xiangbo Zeng,Junpeng Liu,Changsha Zhang,Mingji Shi,Furui Tan,Zhanguo Wang 한국물리학회 2009 Current Applied Physics Vol.9 No.5

Poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) capped PbS nanorods about 100 nm in diameter and 400 nm in length were synthesized via a hydrothermal route in toluene and dimethylsulfoxide solution. By blending the PbS nanorods with the MDMO-PPV as the active layer, bulk heterojunction solar cells with an indium tin oxide (ITO)/polyethylenedioxythiophene/polystyrenesulphonate (PEDOT: PSS)/MDMO-PPV: PbS nanorods/Al structure were fabricated in a N2 filled glove box. Current density–voltage characterization of the devices showed that the solar cells with PbS nanorods hybrid with MDMO-PPV as active layer were better in performance than the devices with the polymer only.

Interfacial behaviors in Cu/molten Sn–58Bi/Cu solder joints under coupling with thermal and current stressing

Fengjiang Wang,Hong Chen,Dongyang Li,Zhijie Zhang,Xiaojing Wang 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.1

The interfacial behaviors of Cu/molten Sn–58Bi/Cu solder joints under the coupling eff ect of a temperature gradient and thecurrent stressing have been investigated. The most obvious change of the interfacial behaviors under the individual electromigration(EM) and thermomigration (TM) in molten solder was the asymmetrical growth of interfacial Cu–Sn intermetalliccompounds (IMCs), which grew rapidly as the stressing time prolonged. The growth rates of the interfacial IMCs inducedby TM under a temperature gradient of 40 °C/cm were slightly faster than EM under the current density of 0.5 × 10 4 A/cm 2 . However, the microstructure evolution and interfacial behaviors changed obviously when the thermal was distributedunevenly across the entire solder stripe under current stressing. It was found that there was a Bi-rich layer adhered to theanode side and a distributed Cu 6 Sn 5 phase existed in the solder matrix when the anode and the cold end were at the sameend. Additionally, a large number of Bi-blocks and Cu–Sn IMCs were dramatically observed in the solder matrix when theanode and the hot end were on the same side. The main reason for this result may be attributed to the signifi cant change ofthe diff usion of Bi atoms under the thermo-electric coupling conditions. In the initial melting stage of solder, the Bi atomsin molten Sn–58Bi solder rapidly diff used to the anode and then began to be reversely dissolved into the solder matrix. Theexperimental results proved the additional temperature gradient played a positive or negative role on the reverse dissolutionof Bi atoms in the heat preservation process.

Beyond Canonical PROTAC: Biological targeted protein degradation (bioTPD)

Huifang Wang,Runhua Zhou,Fushan Xu,Kongjun Yang,Liuhai Zheng,Pan Zhao,Guangwei Shi,Lingyun Dai,Chengchao Xu,Le Yu,Zhijie Li,Jianhong Wang,Jigang Wang 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Targeted protein degradation (TPD) is an emerging therapeutic strategy with the potential to modulate disease associated proteins that have previously been considered undruggable, by employing the host destructionmachinery. The exploration and discovery of cellular degradation pathways, including but not limited toproteasomes and lysosome pathways as well as their degraders, is an area of active research. Since the conceptof proteolysis-targeting chimeras (PROTACs) was introduced in 2001, the paradigm of TPD has been greatlyexpanded and moved from academia to industry for clinical translation, with small-molecule TPD being particularlyrepresented. As an indispensable part of TPD, biological TPD (bioTPD) technologies including peptide-, fusionprotein-, antibody-, nucleic acid-based bioTPD and others have also emerged and undergone significantadvancement in recent years, demonstrating unique and promising activities beyond those of conventional small molecule TPD. In this review, we provide an overview of recent advances in bioTPD technologies, summarize theircompositional features and potential applications, and briefly discuss their drawbacks. Moreover, we present somestrategies to improve the delivery efficacy of bioTPD, addressing their challenges in further clinical development.

Stem cells from human exfoliated deciduous teeth attenuate trigeminal neuralgia in rats by inhibiting endoplasmic reticulum stress

Yang, Zhijie,Wang, Chun,Zhang, Xia,Li, Jing,Zhang, Ziqi,Tan, Zhao,Wang, Junyi,Zhang, Junyang,Bai, Xiaofeng The Korean Pain Society 2022 The Korean Journal of Pain Vol.35 No.4

Background: The treatment of trigeminal neuralgia remains a challenging issue. Stem cells from human exfoliated deciduous teeth (SHED) provide optimized therapy for chronic pain. This study aimed to investigate the mechanisms underlying the attenuation of trigeminal neuralgia by SHED. Methods: Trigeminal neuralgia was induced by chronic constriction injury of the infraorbital nerve. The mechanical threshold was assessed after model establishment and local SHED transplantation. Endoplasmic reticulum (ER) morphology and Caspase12 expression in trigeminal ganglion (TG) was evaluated as well. BiP expression was observed in PC12 cells induced by tunicamycin. Results: The local transplantation of SHED could relieve trigeminal neuralgia in rats. Further, transmission electron microscopy revealed swelling of the ER in rats with trigeminal neuralgia. Moreover, SHED inhibited the tunicamycin-induced up-regulated expression of BiP mRNA and protein in vitro. Additionally, SHED decreased the up-regulated expression of Caspase12 mRNA and protein in the TG of rats caused by trigeminal neuralgia after chronic constriction injury of the infraorbital nerve mode. Conclusions: This findings demonstrated that SHED could alleviate pain by relieving ER stress which provide potential basic evidence for clinical pain treatment.

Analysis on Ampacity of Overhead Transmission Lines Being Operated

Zhijie Yan,Yanling Wang,Likai Liang 한국정보처리학회 2017 Journal of information processing systems Vol.13 No.5

Dynamic thermal rating (DTR) system is an effective method to improve the capacity of existing overheadline. According to the methodology based on CIGRE (International Council on Large Electric systems)standard, ampacity values under steady-state heating balance can be calculated from ambient environmentalconditions. In this study, simulation analysis of relations between parameters and ampacity is described asfunctional dependence, which can provide an effective basis for the design and research of overheadtransmission lines. The simulation of ampacity variation in different rating scales is described in this paper,which are determined from real-time meteorological data and conductor state parameters. To test theperformance of DTR in different rating scales, capacity improvement and risk level are presented. And theexperimental results show that the capacity of transmission line by using DTR has significant improvement,with low probability of risk. The information of this study has an important reference value to the operationmanagement of power grid.

Twin Minimax Probability Machine for Handwritten Digit Recognition

Zhijie Xu,Jianqin Zhang,Hengyou Wang 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.2

Handwritten digit recognition is a task of great importance in many applications. There are different challenges faced while attempting to solve this problem. It has drawn much attention from the field of machine learning and pattern recognition. Minimax probability machine (MPM) is a novel method in machine learning and data mining. In this paper, we present an extension algorithm for MPM, which is named twin minimax probability machine (TWMPM). TWMPM generates two hyperplanes to improve the classification accuracy. Experiment results on several data sets from the UCI repository demonstrate that TWMPM can improve performance of MPM in most cases. The proposed method is used for recognizing the handwritten digits provided in the MNIST data set of images of handwritten digits (0-9). The testing accuracies are improved comparing with MPM.

Improved Received Signal Strength Ratio Based High Accuracy Indoor Visible Light Positioning Scheme

Zhijie Luo,JinHua Wang,WenWen Zhao,JianKun Luo,WeiNan Zhang,GuoFu Zhou 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.12

With the increasingly development of Light-emitting Diode (LED) lighting, in this paper, we proposed an Indoor Visible Light Positioning (VLP) Scheme by using visible LED lights for accurate localization. The basic idea of the position scheme is to improve received signal strength ratio algorithm. Received signal strength ratio (RSSR) is the relative ratio of optical powers detected between each LED and optical receiver. In this paper, we introduce concept of multiple LEDs selection to improve RSSR positioning algorithm. By three LEDs are reasonably selected from the multiple LEDs deployed in the room, the positioning accuracy of RSSR is improved. The system can be employed easily because it does not require additional sensors and occlusion problem in visible light would be alleviated. In addition, we performed the simulation experiments, and confirmed the feasibility of our proposed method.