Core–Shell Grain Structure and High Energy Storage Performance of BNT-Based Relaxor Ferroelectric Ceramics

Zixin Zhang,Renhui Tan,Fangfang Wan,Kang Yan 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.2

Bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) based ferroelectric ceramic is one of the important lead free dielectric materialsfor high energy storage applications due to its large polarization. Herein, we reported a modified BNT based relaxor ferroelectricceramics composited with relaxor Sr0.7Bi0.2TiO3(SBT) and ferroelectric BaTiO3(BT), which exhibits a high recoverableenergy density of 5.59 J/cm3 and a high energy storage efficiency of 84.0% under large breakdown electric strengthof 420 kV/cm. A core–shell grain structure is observed in the BNT-SBT-BT ceramics with high content BT additive, whichplays crucial role on the enhancement of the energy storage performance. This ceramic also exhibits superior temperaturestability with small energy density variation of less than 6.5% in wide temperature range from room temperature to 180 °C. The impedance spectroscopies show that the ceramics have good insulation properties at high temperature. These characteristicsdemonstrate that the BNT-SBT-BT ceramic is a promising candidate for high-power energy storage applications.

Pectin oligosaccharides improved lipid metabolism in white adipose tissue of high-fat diet fed mice

Zixin Fan,Xuejiao Chen,Tianzhi Liu,Qianhui Yu,Ziqi Song,Fei Wang,Tuoping Li 한국식품과학회 2022 Food Science and Biotechnology Vol.31 No.9

Impacts of pectin oligosaccharide (POS) got from hawthorn fruitage on adiponectin signaling pathway and white adipose metabolism in mice fed with high-fat control. The results showed that POS significantly inhibited the levels of inflammatory cytokines TNF-α and IL-6, and down-regulated expression of CD68. POS dramatically reduced gene expression contents of fatty acid composite concerning enzymes ACC and FAS, as well as TG synthesis-related enzymes SCD-1 and DGAT1 as compared to a high-fat group (HFC). POS dramatically increased expression levels of oxidation-related enzymes of fatty acid ACO, CPT-1, and TG deposition-related enzymes ATGL and HSL as contrast to the high-fat control group. In addition, POS activated adiponectin-mediated AdipoR1/AMPK/PPARα signaling path by upregulating expression levels of AdipoR1, AMPK and PPARα. The results demonstrated that POS can improve lipid metabolism of adipose tissue, and contribute to the creation of functional foods to prevent and treat lipid metabolism disorders.

Virtual Model Reduction-based Control Strategy of Planar Three-link Underactuated Manipulator with Middle Passive Joint

Zixin Huang,Xuzhi Lai,Pan Zhang,Yawu Wang,Min Wu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.1

This paper presents a position control strategy for a planar active-passive-active (APA) underactuatedmanipulator with second-order nonholonomic characteristics. According to the structural characteristics of the planar APA system, we divide the system into two parts: a planar virtual Pendubot (PVP) and a planar virtual Acrobot(PVA). For the PVP, we mainly fulfill the target angle of the first link, which is calculated through the geometrymethod, and make the system stable. In this stage, via keeping the states of the third link being zero, the system isreduced to the PVP. Meanwhile, we design an open-loop control law based on the nilpotent approximation (NA)model of the PVP to make the second link stable and the first link stabilize at its target angle. Then, the planar APAsystem is reduced to a PVA with all links’ angular velocities being zero. For the PVA, we mainly realize the othertwo links’ target angles obtained via the particle swarm optimization (PSO) algorithm. Thus, the control objectiveof the planar APA system is achieved. Finally, above control strategy is verified by simulation results.

Effect of the Ag-doping on the phase structural evolution, dielectric and ferroelectric properties of lead-free niobate ceramics

Huining Wang,Zixin Zhang,QuanSen Yang,Fangfang Wang,Kang Yan 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.2

Ionic doping is an important approach to modification of crystal structure and physical properties of the piezoelectric ceramics. In this work, the lead-free piezoelectric ceramic (1- x )K 0.18 Na 0.74 Li 0.08 NbO 3 - x AgNbO 3 (abbreviated as KNLN- x AN, 0 ≤ x ≤ 0.8) was prepared by conventional solid-state reaction method. The effect of the Ag doping on the phase structure, dielectric and ferroelectric properties of the KNLN-based ceramics was investigated by the XRD, DSC, dielectric and ferroelectric characterizations. It is found that all KNLN- x AN ceramics show single phase in perovskite structure because the ionic radii of dopant Ag close to the average ionic size at the A-site in KNLN. The KNLN- x AN exhibits the rhombohedral to orthorhombic phase transition at room temperature and the Curie temperature ( T C ) decreases to low temperature with increasing x value. A narrow tetragonal phase region and a wide orthorhombic phase region form for the compositions with x ≥ 0.4, indicating that the Ag doping stabilizes orthorhombic phase in wide temperature for the KNLN. A ferroelectric anomalies due to high electrical field induced phase transition is found in the sample with x = 0.1. When x = 0.4, high Curie temperature ( T C = 380 °C), large remnant polarization ( P r = 24.4 μC/cm 2 ) and high dielectric constant ( ε r = 10,000 at 1 kHz) at T C are achieved.

Analysis of Strong Stress Concentrations of Key Joints for Super-Spanned Steel Truss Bridges

Cong Li,Zixin Song,Guanghui Xia,Xiaofang Kang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

In this paper, the strategy of three scales was proposed to analyse strong stress distributions of key joints during the incremental launching construction. Firstly, the internal forces and reaction forces were obtained by the finite element method (FEM). Secondly, some key joints were separated from the whole structure. The displacements and boundary conditions of the separated joint were taken from the results of the FEM. Then the stress distributions of the separated joint were successfully obtained by using the FEM. Thirdly, the local stress concentration areas were separated from the key joint structure. The high stress distributions of the local stress concentration region were successfully obtained by using the extended boundary element method (XBEM). On the other hand, the stress of some joints were measured through mechanical test on the construction site. And calculation results of the FEM and XBEM were in good agreement with test results. A multi-scale method is developed to obtain the strong stress concentration during the construction of the super-spanned steel truss bridge accurately, which enables the safety of the construction. In addition, the present method can be further used to guide the design of super-tall building, super-spanned bridge, etc.

Effect of Ammonium in Medium on Ansamitocin P-3 Production by Actinosynnema pretiosum

Jinxia Lin,Linquan Bai,Zixin Deng,Jian-Jiang Zhong 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.1

Ansamitocin P-3 (AP-3) is an antitumor agent produced by Actinosynnema pretiosum with a market demand for large and cheap supply, but its productivity is yet low. This work investigated the effects of ammonium in medium on the productivity, enzyme activities, and gene transcription for AP-3 biosynthesis. As observed, AP-3 production was depressed by medium ammonium, although the dry cell weight and the consumption of total sugar and isobutanol were not influenced obviously. From the onset of AP-3 accumulation, isobutyrate accumulation showed a different behavior in medium with or without ammonium. Isobutanol dehydrogenase activity was enhanced during production phase in medium with ammonium, but valine dehydrogenase activity was not substantially changed. qRT-PCR analysis revealed that transcriptional levels of structure genes asm14, asm24, asm43, and asm19 were down-regulated by medium ammonium. The transcription of regulatory gene asm2, asm29, and asm31 were slightly up-regulated while that of asm39 was down-regulated by ammonium. The results indicated that inhibition of AP-3 production by ammonium might be related to the AP-3 ester side chain supply and the repression of gene transcription responsible for 3-amino-5-hydroxybenzoic acid and methoxymalonyl-ACP biosynthesis. The information is useful for future AP-3 productivity enhancement.

Analytical loss model of series-resonant indirect-matrix-type power electronics transformers using MOSFETs

Hu, Yujie,Li, Zixin,Zhao, Cong,Li, Yaohua The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.11

A MOSFET-based series-resonant indirect-matrix-type power electronic transformer (PET) consists of line-frequency-switching folding-unfolding bridges and series-resonant dc-dc converters (SRCs), which is an attractive choice to achieve ac-ac conversion due to its high efficiency and high power density. However, the conduction losses, switching losses, and core losses in each of the high-frequency switching cycles T_s are different due to the pulsating dc voltage |ac|, which introduces difficulties in the calculation of losses. In addition, the small dc capacitors also participate in the resonance, and the resonant current shape deviates from a pure sine. Therefore, the conventional loss model is not suitable for PETs. In this paper, the time-domain analysis of SRC resonant current considering the dc capacitor is developed. Then, the analytical expression of the resonant current RMS value in grid cycle T_g is derived, which is more accurate in calculating conduction loss than the conventional model. In addition, it avoids the calculating losses in each T_s. Next, an analytical switching loss model is developed based on the curve fitting of the capacitance-voltage relationship. A simplified analytical core loss model is provided. Each part of the loss of the PET is verified by thermal simulations, and the total losses are verified by efficiency tests on an experiment prototype.

Development of Recombinase Polymerase Amplification Combined with Lateral Flow Strips for Rapid Detection of Cowpea Mild Mottle Virus

Xinyang Wu,Shuting Chen,Zixin Zhang,Yihan Zhang,Pingmei Li,Xinyi Chen,Miaomiao Liu,Qian Lu,Zhongyi Li,Zhongyan Wei,Pei Xu 한국식물병리학회 2023 Plant Pathology Journal Vol.39 No.5

Cowpea mild mottle virus (CPMMV) is a global plant virus that poses a threat to the production and quality of legume crops. Early and accurate diagnosis is essential for effective managing CPMMV outbreaks. With the advancement in isothermal recombinase polymerase amplification and lateral flow strips technologies, more rapid and sensitive methods have become available for detecting this pathogen. In this study, we have developed a reverse transcription recombinase polymerase amplification combined with lateral flow strips (RT-RPA-LFS) method for the detection of CPMMV, specifically targeting the CPMMV coat protein (CP) gene. The RT-RPA-LFS assay only requires 20 min at 40°C and demonstrates high specificity. Its detection limit was 10 copies/μl, which is approximately up to 100 times more sensitive than RT-PCR on agarose gel electrophoresis. The developed RT-RPA-LFS method offers a rapid, convenient, and sensitive approach for field detection of CPMMV, which contribute to controlling the spread of the virus.

New currents: 관상동맥 경화반(coronary plaque) 측정 시 사용되는 PC-VENC 기법을 이용한 MR-FFR(Fractional Flow Reserve) 측정 방법의 유용성

도지훈,이길백,박시섭,박순규,김윤국,임재식,Zixin Deng 대한자기공명기술학회 2016 대한자기공명기술학회지 Vol.26 No.-

목 적 : Fractional Flow Reserve(분획혈류예비력:FFR)은 관상동맥 질환이 있는 환자에서 중간 동맥 협착의 기능적 중요성을 평가하는 방법이다. 이는 관상동맥 협착 부위의 원위부와 근위부 정상혈관의 최대 혈류량의 비율(ΔP)을 말하며 카데터(catheter)가 혈관에 삽입되어 FFR 측정 위치까지 이동되는 방법이 사용된다. 그러나 이 방법은 침습적(invasive)이어서 환자가 불편하고, 신체에 손상을 줄 위험이 있어 비침습적(non-invasive) 방법으로 혈관의 병변(lesions)을 진단 및 평가하는 방법이 주목 받고 있다. 이중 MRI PC-VENC 기법을 이용한 MR-FFR이 그 대안으로 평가되고 있어 MR-FFR 사용에 대한 임상적 유용성을 알아보고자 한다. 대상 및 방법 : 2015년 8월부터 2015년 12월까지 관상동맥의 근위부에 의미 있는 동맥경화반이 관찰되어 FFR측정이 예정된 환자 5명과 건강한 성인 11명에 대해 MR-FFR 검사를 진행하였다. 3.0T MRI 장비를 사용하였고 코일은 phased-array body coil을 사용하였다. CT에서 재구성된 관상동맥 경화반의 범위를 참조하여 coronary LAD MPR(multi planner reconstruction) 영상을 만든 후 혈관의 정상 부위와 동맥 경화반 부위를 포함하여 scan 부위를 결정하여 PC-VENC 영상을 얻는다. 사용된 parameter는 VENC=35-65cm/s in all 3 directions, FA=15˚, cardiac phase=2(70ms/phase), in-plane resolution =0.5-0.6×0.5-0.6mm², slice thickness=3.2mm, scan time은 2-6 min/slice으로 설정하였다. 얻어진 VENC 영상에서 ΔPMR를 구하기위해 MATLAB을 사용하여 각 슬라이스에서 산출된 최대 속도를 적분하여 Navier-Stokes(NS) 공식을 이용하여 data를 산출하였다. 결 과 : Proximal left anterior descending coronary artery(pLAD)에서 stenosis의 area percentage가 증가 할수록 ΔPMR 값을 산출할 수 있는 mmHg 값도 높게 나타났다. 이는 stenosis 정도가 심할수록 분획혈유예비력(FFR) 값이 증가함을 의미하며 기존 FFR을 구하는 방식과 비교했을 때 환자 군(6.40±4.43mmHg), 정상군(0.62±0.49mmHg)에서 유의한 값(p<0.001)으로 나타났다. 기존 FFR 과 MR-FFR 간 결정계수 값은 R2=0.938으로 나타나 MR-FFR 기법과 기존 FFR 측정차가 크게 없음을 알 수 있었다. 결 론 : 현재까지 진행된 연구에서 관상동맥 경화반이 있는 혈관과 정상 혈관 모두에서 기존 FFR 값과 비교했을 때 ΔPMR 분석은 매우 유의한 값을 나타내고 있었다. 이에 따라 다른 종류의 침습적인 방법인 intravascular ultrasound(IVUS), optical coherence tomography (OCT) 등를 이용한 FFR 과 MR-FFR의 비교 연구가 진행되고 있으며 또한 공간적, 시간적 해상도 및 노이즈 감소의 관점에서 기술의 개선과 정확성을 향상시키기 위한 시퀀스 개발도 진행되고 있다. 따라서 비침습적이고 피폭이 없으며 환자에게 유용한 정보가 많은 MR-FFR 측정 방법은 앞으로 임상에서 유용하게 쓰여질 것으로 판단된다.

Relay selection and Optimization algorithm of Power allocation based on Channel Delay for UWSN

YunLi,Zhigang Jin,Xunjun Wang,Zixin Liu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.2

In the light of the characteristics of random change that underwater sensor change by time, space and frequency, select the best relay node to improve communication quality and get the diversity gain. A new optimal relay selection method is proposed in this paper, by considering two indexes synthetically that channel gain and underwater acoustic communication long time delay to select the best relay node. Based on the best relay node and minimization of bit error rate to take optimal power allocation of source node and relay node to realize network error rate’s reduction of 1.81 dB so then improve the overall performance of the network.