Simulation and Analysis of Magnetic Circuit of Water-cooling Magnetorheological Fluid Transmission Device

Jinjie Ji,Zuzhi Tian,Xiangfan Wu,Jin Dou 한국자기학회 2018 Journal of Magnetics Vol.23 No.1

Aiming to solve the problem of magnetorheological transmission heat dissipation, this study designs the magnetic circuit of a water-cooling magnetorheological transmission device based on fundamental electromagnetics theory. Finite element method is used to simulate the magnetic field of the measurement device. Results show that the working magnetic induction can reach 0.56 T when the current is 2.0 A, which can satisfy design requirements. The intensity of magnetic induction in the work space increases with the increase of excitation current and permeability of magnetically conductive material, whereas intensity decreases with the increase of work space size. The thickness and cross-sectional dimension of the guidepost group at the heat-dissipating unit have no significant effect on the intensity distribution of magnetic induction of the entire device.

Genetic architecture of flag leaf length and width in rice (Oryza sativa L.) revealed by association mapping

Jiantao Wu,Yongwen Qi,Guanglong Hu,Jinjie Li,Zichao Li,Hongliang Zhang 한국유전학회 2017 Genes & Genomics Vol.39 No.3

Rice flag leaf is the main photosynthetic organ and plays a key role in grain yield. In this study, 106 loci associated with flag leaf length and width were identified using association mapping in a rice mini core collection. Analyzing the phenotypic effects of each allele represented 156 positive and 167 negative alleles, with a few alleles showing inconsistent effect in different environments. Among the 106 loci, 69 were environment-specific loci, 16 were environmentally stable and 21 were environmentally sensitive. Fifteen associated markers were shared by two traits and were designated as pleiotropic markers. According to the frequency distribution of alleles in different variety types, 343 alleles were categorized into three types based on geographic source and usage in breeding. Among these, 156 were used alleles, 138 were unused and 49 were foreign alleles. The results further our understanding of the genetic mechanisms of flag leaf length and width.

Effect on the Sedimentation Stability of Magnetorheological Fluid by Micro-nano Composite System

Ji Jinjie,Wu Xiangfan,Tian Zuzhi 한국자기학회 2023 Journal of Magnetics Vol.28 No.2

In magnetorheological devices, the magnetorheological fluids are inevitably in a zero-field state when the MR device is out of work. Long-term placement will lead to the sedimentation of MR fluids, reducing the performance of the magnetorheological device. A novel magnetorheological fluid was prepared by mixing microparticles and nanoparticles to solve this problem. After one-week placement, the sedimentation rate of the novel magnetorheological fluid is only 0.23 %, decreased by 88.5 % compared with general magnetorheological fluid. The novel magnetorheological fluid shows excellent sedimentation stability, keeping magnetorheological devices in good condition.

Study on the Correction Method for the Dead-time Effects of Neutron Detectors Due to Pulsed Radiation

Siming Guo,Jinjie Wu,Zhongjian Ma,Guanjia Li,Qingbin Wang 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.4

Gas detectors based on a 3He proportional counter play an important role in monitoring the ambient dose equivalent in nuclear reactors and particle accelerators, and the time resolution of such gas detectors is directly related to the accuracy of dose equivalent values when gas detectors are used in pulsed neutron fields. In this article, the dead-time of a proportional 3He counter is measured experimentally, and two methods to correct for the omitted counts resulting from the dead-time effect are adopted. The moderation time of neutrons passing through the moderator of a neutron detector is calculated by means of Monte Carlo simulation software; thus, the equation between the neutron counting rate and the correction coecient in accelerator radiation fields is deduced. In the other method, the parameters of the correction equation are derived experimentally in the pulsed radiation fields around accelerators, and the correction equation is determined. The dead-time effects of neutron detectors due to pulsed radiation can be corrected effectively by using the two methods introduced in this paper.

Anti-neuroinflammatory Activity of Nobiletin on Suppression of Microglial Activation

Cui, Yanji,Wu, Jinji,Jung, Sung-Cherl,Park, Deok-Bae,Maeng, Young-Hee,Hong, Jeong Yun,Kim, Se-Jae,Lee, Sun-Ryung,Kim, Soon-Jong,Kim, Sang Jeong,Eun, Su-Yong Pharmaceutical Society of Japan 2010 BIOLOGICAL & PHARMACEUTICAL BULLETIN Vol.33 No.11

<P>A growing body of evidence suggests that nobiletin (5,6,7,8,3′,4′-hexamethoxy flavone) from the peel of citrus fruits, enhances the damaged cognitive function in disease animal models. However, the neuroprotective mechanism has not been clearly elucidated. Since nobiletin has shown anti-inflammatory effects in several tissues, we investigated whether nobiletin suppresses excessive microglial activation implicated in neurotoxicity in lipopolysaccharide (LPS)-stimulated BV-2 microglia cell culture models. Release of nitric oxide (NO), the major inflammatory mediator in microglia, was markedly suppressed in a dose-dependent manner following nobiletin treatment (1—50 μ<SMALL>M</SMALL>) in LPS-stimulated BV-2 microglia cells. The inhibitory effect of nobiletin was similar to that of minocycline, a well-known microglial inactivator. Nobiletin significantly inhibited the release of the pro-inflammatory cytokine tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β). LPS-induced phosphorylations of extracellular signal-regulated kinase (ERK), c-Jun NH<SUB>2</SUB>-terminal kinase (JNK), and p38 mitogen-activated protein kinases (MAPKs) were also significantly inhibited by nobiletin treatment. In addition, nobiletin markedly inhibited the LPS-induced pro-inflammatory transcription factor nuclear factor κB (NF-κB) signaling pathway by suppressing nuclear NF-κB translocation from the cytoplasm and subsequent expression of NF-κB in the nucleus. Taken together, these results may contribute to further exploration of the therapeutic potential and molecular mechanism of nobiletin in relation to neuroinflammation and neurodegenerative diseases.</P>

Experimental Measurement and Monte Carlo Simulation the Correction Factor for the Medium-Energy X-ray Free-air Ionization Chamber

Yu Jili,Wu Jinjie,Liao Zhenyu,Zhou Zhenjie 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.10

A key comparison has been made between the air-kerma standards of the National Institute of Metrology (NIM), China, and other Asia Pacific Metrology Programme (APMP) members in the medium-energy X-ray. This paper reviews the primary standard Free-air ionization chamber correc- tion factor experimental method and Monte Carlo simulation method in the NIM. The experimental method and the Monte Carlo simulation method are adopted to obtain the correction factor for the medium-energy X-ray primary standard free-air ionization chamber at 100 kV, 135 kV, 180 kV, 250 kV four CCRI reference qualities. The correction factor has already been submitted to the APMP as key comparison data and the results are in good agreement with those obtained in pre- vious studies. This study shows that the experimental method and the EGSnrc simulation method are usually used in the measurement of the correction factor. In particular, the application of the simulation methods is more common.

Research on the temperature characteristics of SiPM-based LaBr3(Ce) detectors

Yu Tao,Guo Siming,Wu Jinjie,An Zhenghua,Qie Xiaoyu,Guo Kaiyue 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.1

When a satellite-borne detector is being ground calibrated, a standard detector is required to determine the monochromatic X-ray beam energy and intensity. For this purpose, a SiPM-based LaBr3(Ce) detector has been developed. The environmental temperature change may substantially afect the performance of the detector, thus afecting the accuracy of the ground calibration results. To study the efect of temperature change on the performance of the LaBr3(Ce) detector, the performance of the LaBr3(Ce) detector was tested with 241Am and 137Cs γ-ray sources in the high- and low-temperature test chambers. The results showed that within the range of – 20 to 40 °C, the energy resolution of the LaBr3(Ce) detector does not change by more than 1%, nor does the peak-to-total ratio of 241Am and 137Cs. The temperature change has little efect on the performance of the LaBr3(Ce) detector, which meets the requirements for use as a beam monitor. However, the peak location of the radioactive source varies signifcantly with temperature, and the diference with the peak location at room temperature is within 17%. To reduce the variation in the gain of the LaBr3(Ce) detector with temperature, it is necessary to optimize the compensation design of the temperature gain to ensure the stability of the detector gain at various temperatures.

Unified coordination control strategy for DC solid‑state transformer in DC microgrid

Yanbing Jia,Pei Zhao,Jinjie Tian,Xiangqi Meng,Han Wu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8

The existing control strategies of DC solid-state transformer (DCSST) are based on DC distribution system, which is mainly concentrated on one side voltage stability control without considering the change of control objectives under different conditions. Thus, they are unsuitable for multiterminal and multisource DC microgrid. The coordinated control strategy of DCSST in multiterminal and multisource DC microgrid is studied in this paper. The DCSST circuit models based on the series–parallel structure of dual active full bridge converter are established, and the basic control modes are analyzed: control low voltage mode and control high voltage mode. Combined with the characteristics of DC bus voltage fluctuation and the operation conditions of DCSST, a unified coordinated control strategy is proposed. Experimental results show that the proposed control strategy can correctly identify the different power states of the two sides of the system, control the power exchange between the two sides of the system, and maintain the stable operation of the whole DC system.

Nobiletin attenuates neurotoxic mitochondrial calcium overload through K+ influx and ΔΨm across mitochondrial inner membrane

Ji Hyung Lee,Khulan Amarsanaa,Jinji Wu,Sang-Chan Jeon,Yanji Cui,Sung-Cherl Jung,Deok-Bae Park,Se-Jae Kim,Sang-Heon Han,Hyun-Wook Kim,Im Joo Rhyu,Su-Yong Eun 대한생리학회-대한약리학회 2018 The Korean Journal of Physiology & Pharmacology Vol.22 No.3

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (ΔΨm). Therefore, pharmacological manipulation of ΔΨm can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ΔΨm against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity (100 μM,20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate (100 μM)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of Ca2+ (5 μM). Nobiletininduced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ΔΨm were completely abolished in K+-free medium on pure isolated mitochondria. Taken together, results demonstrate that K+ influx into mitochondria is critically involved in partial mitochondrial depolarization–related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial K+ influx is probably mediated, at least in part, by activation of mitochondrial K+ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.

Determination of the air-kerma in mammography x-rays at NIM

Ji Wang,Siming Guo,Pingzhou Lu,Jinjie Wu,Ying Liu,Ruonan Li,Yulong Wang 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.4

Breast cancer has become the top killer of women’s health in the world, and mammography X-ray has become the gold standard in various diagnostic methods, due to its low energy, low dose and high resolution. To meet the quality control requirements of mammography X-rays dose in clinical, the National Institute of Metrology (NIM,China) has established a mammography X-ray reference radiation facility. The radiation quality half-value layer (HVL) range from 0.274 to 0.364 mm (aluminum) meets the requirements of IEC61267, and a new parallel-plate free-air ionization is designed. At NIM, various correction factors were measured and simulated, and fnally, the absolute measurement of the X-ray air kerma rate of the mammography was realized. By analysis, the combined standard uncertainty of the air kerma is 0.44%. Provide traceability services for the use and quality control of mammography in China.